JP6536355B2 - Sole operation detection device, control device, power conditioner, power supply system, and sole operation detection method - Google Patents

Description

  The present invention relates to an islanding detection device, a control device, a power conditioner, a power supply system, and an islanding detection method.

When it is detected that the power conditioner connected to the system power supply is operating alone when the system power supply is stopped, the power conditioner is stopped. For example, as described in Patent Document 1, the reactive power supplied to the system power supply side is changed according to the frequency deviation of the system power supply, and the isolated operation of the power conditioner is detected based on the frequency fluctuation of the reactive power. ing.
Patent Document 1: Japanese Patent Application Publication No. 2009-136095

  For example, if the number of power conditioners linked to the system power supply increases or the output capacity increases, the reactive power supplied to the system power supply side may increase and affect the power system. is there. In addition, when the length of the power system between the grid power supply and the power conditioner is relatively long, a change in reactive power may act on the impedance in the power system to affect the voltage of the power system.

  The islanding operation detecting device according to one aspect of the present invention is an islanding operation detecting device that detects an islanding operation of a power conversion unit linked to an AC power supply, and a frequency deviation deriving unit that derives the frequency deviation of the AC power supply A first reactive power deriving unit for deriving a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived by the frequency deviation deriving unit; and the power conversion unit outputs The power conversion unit outputs the voltage change amount deriving unit for detecting the islanding operation based on the voltage change amount deriving unit that derives the voltage variation amount of the voltage and the first reactive power amount derived by the first reactive power amount deriving unit A first reactive power amount for adjusting the target reactive power amount derived by the target reactive power amount deriving unit based on a target reactive power amount deriving unit for deriving a target reactive power amount to be calculated and the magnitude of the voltage change amount Perform the adjustment And a reactive power amount adjuster.

  The reactive power adjustment unit is a target derived by the target reactive power deriving unit based on the voltage change amount changing in a cycle range determined based on a flicker cycle occurring in the voltage output from the AC power supply. The first reactive power adjustment may be performed by adjusting the reactive power.

  The reactive power adjustment unit adjusts the target reactive power such that temporal change in the target reactive power derived by the target reactive power deriving unit becomes gradual as the magnitude of the voltage change increases. The first reactive power adjustment may be performed by adjusting the target reactive power that the amount deriving unit derives.

  The apparatus further comprises: a voltage change acquisition unit acquiring a voltage change of the voltage output from the AC power supply; and a correlation function deriving unit deriving a correlation function indicating a correlation between the frequency deviation and the voltage change. The reactive power adjustment unit may perform the first reactive power adjustment according to the value indicated by the correlation function derived by the correlation function deriving unit.

  The correlation function deriving unit may derive the correlation function with respect to the frequency deviation and the voltage change amount changing in a cycle range determined based on a flicker cycle occurring in a voltage output from the AC power supply.

  The reactive power amount adjustment unit derives the adjusted reactive power amount based on the voltage change amount, and the target reactive power amount deriving unit calculates the current target based on the first reactive power amount and the adjusted reactive power amount. The first reactive power adjustment may be performed by deriving the reactive power.

  When the voltage change amount is within a predetermined voltage change amount range, the reactive power amount adjustment unit derives an adjustment reactive power amount based on the voltage change amount, and adjusts the first reactive power amount and the adjustment. The first reactive power adjustment may be performed by causing the target reactive power derivation unit to derive the current target reactive power based on the reactive power.

  When the voltage change amount is out of the voltage change amount range, the reactive power amount adjustment unit generates the target reactive power amount calculation unit based on a predetermined reference adjustment reactive power amount and the first reactive power amount. The first reactive power adjustment may be performed by causing the target reactive power amount of this time to be derived.

  The reactive power adjustment unit changes temporally the target reactive power derived by the target reactive power deriving unit at a predetermined timing after the frequency deviation falls outside a predetermined deviation range. A second reactive power adjustment may be further performed to adjust the target reactive power which the target reactive power deriving unit derives so that the value of s.

  After the second reactive power adjustment is started, the reactive power adjustment unit may continue the second reactive power adjustment for a predetermined period.

  The reactive power amount adjustment unit starts the second reactive power amount adjustment, and after the frequency deviation falls within a predetermined deviation range, the second reactive power is maintained for a predetermined period. Volume adjustments may continue.

  The predetermined period may be determined based on at least one of a period and a magnitude of flicker occurring in a voltage output from the AC power supply.

  The predetermined period may be determined based on at least one of the magnitude and the period of the reactive power output by the islanding operation detection device.

  The reactive power amount adjustment unit may start the second reactive power amount adjustment after the frequency deviation is out of a predetermined deviation range and a predetermined standby period has elapsed.

  The conditions for starting the second reactive power adjustment of the reactive power adjustment unit may be determined based on the magnitude and the cycle of reactive power output by the islanding operation detection device.

  When the frequency deviation derived by the frequency deviation deriving unit is positive, the reactive power adjustor adjusts the provisional current target derived based on the first reactive energy by the target reactive power deriving unit. When the amount of change obtained by subtracting the previous target reactive power derived by the target reactive power deriving unit from the reactive power is smaller than the first reference change, the above-mentioned target reactive power is used as the current target reactive power. The second reactive power adjustment may be performed by causing the target reactive power derivation unit to derive the current target reactive power based on the previous target reactive power and the first reference change amount.

  When the frequency deviation derived by the frequency deviation deriving unit is negative, the reactive power adjustor adjusts the temporary current target derived based on the first reactive energy by the target reactive power deriving unit. When the amount of change obtained by subtracting the previous target reactive power derived by the target reactive power deriving unit from the reactive power is larger than the second reference change, the above-mentioned target reactive power is used as the current target reactive power. The second reactive power adjustment may be performed by causing the target reactive power derivation unit to derive the current target reactive power based on the previous target reactive power and the second reference change amount.

  The reactive power amount adjustment unit adjusts the target reactive power amount derived by the target reactive power amount deriving unit so that the target reactive power amount becomes zero over a predetermined duration. 2 Reactive power adjustment may be performed.

  The reactive power amount adjustment unit adjusts the target reactive power amount derived by the target reactive power amount deriving unit so that the target reactive power amount becomes zero with a predetermined change amount, thereby the second ineffectiveness. Power regulation may be performed.

  The first reactive power amount deriving unit derives a first reactive power amount based on a first function having a first slope indicating a relationship between a frequency deviation and a first reactive power amount, and the reactive power amount adjusting unit The second reactive power adjustment is performed by causing the first reactive power derivation unit to derive the first reactive power based on a second function having a second slope smaller than the first slope. Good.

  The frequency deviation calculating unit further includes a frequency measuring unit that measures the frequency of the AC power supply for each reference period, and the frequency deviation deriving unit determines a period from the frequency at the latest period measured by the frequency measuring unit to the first number of previous cycles. The latest moving average value, which is the moving average value of each frequency, and the moving average value of the past, which is the moving average value of each frequency from the latest period to the second period prior to the first period The difference between the value and the value is derived as a frequency deviation, and the reactive energy adjustment unit causes the frequency deviation deriving unit to adjust the frequency deviation so that the frequency deviation derived by the frequency deviation deriving unit becomes smaller. The second reactive power adjustment may be performed by causing the first reactive power derivation unit to derive the first reactive power based on the frequency deviation.

  The frequency deviation calculating unit further includes a frequency measuring unit that measures the frequency of the power supply for each reference period, and the frequency deviation deriving unit determines each frequency from the frequency at the latest period measured by the frequency measuring unit to the first previous period by a number The latest moving average value, which is the moving average value of the frequency, and the moving average value of each frequency from the past period before the first period determined from the latest period to the second number period before the past The difference with the moving average value is derived as a frequency deviation, and the reactive energy adjustment unit is configured to set the moving average value in the past to a number greater than the second number from the last period before the first period from the latest period. The frequency deviation is derived by the frequency deviation deriving unit from the difference between the moving average value of each frequency up to the cycle three pieces earlier and the latest moving average value, and the first frequency deviation is derived based on the derived frequency deviation. Reactive energy derivation unit By deriving a first reactive energy, it may perform the second reactive energy adjustment.

  The frequency deviation calculating unit further includes a frequency measuring unit that measures the frequency of the power supply for each reference period, and the frequency deviation deriving unit determines each frequency from the frequency at the latest period measured by the frequency measuring unit to the first previous period by a number The latest moving average value, which is the moving average value of the frequency, and the moving average value of each frequency from the past period before the first time determined from the latest period to the second number period before the past The difference with the moving average value is derived as a frequency deviation, and the reactive energy adjustment unit is configured to calculate a past period before the second time shorter than a first time determined from the latest period as the past moving average value. The frequency deviation is derived by the frequency deviation deriving unit from the difference between the moving average value of each frequency from the period from the previous to the second number and the latest moving average value, and based on the derived frequency deviation Above first reactive power By deriving a first reactive energy to the amount derivation unit may perform the second reactive energy adjustment.

  The reactive power amount adjustment unit executes the second reactive power amount adjustment when the frequency deviation changes in the convergence direction after the frequency deviation is out of the predetermined deviation range. Good.

  The reactive power adjustment unit changes temporal changes in the target reactive power derived by the target reactive power deriving unit when the frequency deviation changes in the convergence direction, and the frequency deviation changes in the diverging direction By adjusting the target reactive power derived by the target reactive power deriving unit so that the target reactive power derived by the target reactive power deriving unit is more gradual than the temporal change of the target reactive power derived by the target reactive power deriving unit. The second reactive power adjustment may be performed.

  The control device according to an aspect of the present invention controls the reactive power output by the power conversion unit based on the islanding operation detection device and the target reactive power derived by the target reactive power deriving unit. And a control unit.

  A power conditioner according to one aspect of the present invention includes the above-described control device, and the above-described power conversion unit controlled by the control device and converting direct current from a distributed power source into alternating current.

  A power supply system according to an aspect of the present invention includes the power conditioner and the distributed power supply.

  The islanding operation detecting method according to an aspect of the present invention is an islanding operation detecting method for detecting an islanding operation of a power conversion unit connected to an AC power supply, and the frequency deviation deriving step of deriving the frequency deviation of the AC power supply A first reactive power amount deriving step of deriving a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived in the frequency deviation derivation step; and the power conversion unit outputs The power conversion unit outputs the electric power for detecting the islanding operation based on a voltage change amount deriving step of deriving a voltage change amount of voltage and the first reactive power amount derived in the first reactive power amount deriving step. First reactive power adjusting the target reactive power derived in the target reactive power deriving step on the basis of the target reactive power deriving step for deriving the target reactive power to be calculated and the magnitude of the voltage change amount Volume adjustment And a target amount of reactive power adjusting step of executing.

  The above summary of the invention does not enumerate all of the features of the present invention. In addition, a subcombination of these feature groups can also be an invention.

The system configuration figure which shows an example of the whole structure of the power supply system which concerns on this embodiment is shown. It is a figure which shows the functional block of an islanding operation detection part. It is a figure for demonstrating the derivation method of a frequency deviation. It is a figure which shows an example of 1st reactive energy q1-frequency deviation characteristic. It is a flowchart which shows an example of the procedure in which the solitary operation estimation part judges whether a power conditioner may be solitary operation. It is a figure which shows an example of the characteristic of the fundamental wave voltage referred when judging whether there is a possibility that the power conditioner is operating alone based on the fundamental wave voltage. It is a figure which shows an example of the characteristic of the fundamental wave voltage referred when judging whether there is a possibility that the power conditioner is operating alone based on the fundamental wave voltage. It is a figure which shows an example of the characteristic of the harmonic distortion voltage referred when judging whether there is a possibility that the power conditioner is operating alone based on the harmonic distortion voltage. It is a figure which shows an example of the characteristic of the harmonic distortion voltage referred when judging whether there is a possibility that the power conditioner is operating alone based on the harmonic distortion voltage. It is a flowchart which shows an example of the procedure which derives target reactive energy. It is a flowchart which shows an example of the procedure which derives target reactive energy. It is a flowchart which shows another example of the procedure which derives target reactive energy. It is a figure which shows the mode of the change of the reactive energy in case the flicker phenomenon has occurred. It is a figure which shows the mode of the change of the reactive energy amount when the flicker phenomenon has not occurred. It is a flowchart which shows an example of the procedure which derives target reactive energy. It is a figure which shows an example of adjustment reactive energy qa-voltage change amount (DELTA) V characteristic. It is a figure which shows another example of the adjustment reactive energy qa-voltage change amount (DELTA) V characteristic. It is a figure which shows the functional block of a reactive energy adjustment part. It is a flowchart which shows another example of the procedure which derives target reactive energy. It is a figure for demonstrating the derivation | leading-out method of the frequency deviation for making the time change of target reactive energy loose. It is a figure for demonstrating the derivation | leading-out method of the frequency deviation for making the time change of target reactive energy loose.

  Hereinafter, the present invention will be described through the embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Moreover, not all combinations of features described in the embodiments are essential to the solution of the invention.

  FIG. 1 is a system configuration diagram showing an example of the entire configuration of a power supply system 1 according to the present embodiment. The power supply system 1 includes a solar cell array 200 and a power conditioner 10. In the solar cell array 200, a plurality of solar cell strings in which a plurality of solar cell modules are connected in series are connected in parallel. The solar cell array 200 is an example of a distributed power supply. As a distributed power source, a gas engine, a gas turbine, a micro gas turbine, a fuel cell, a wind power generator, an electric car, or a storage system may be used.

  The power conditioner 10 boosts the DC voltage output from the solar cell array 200, converts the boosted DC voltage into an AC voltage, and controls the power converter that outputs the power voltage to the system power supply 300, and the power converter. And the control device 100. The power conversion unit includes a capacitor C1, a booster circuit 20, a capacitor C2, an inverter 40, a coil L2, a capacitor C3, and a relay 50. The system power supply 300 is an example of an AC power supply. The power supply system 1 may include another distributed power supply that outputs an AC voltage, such as a gas engine, instead of the system power supply 300, separately from the distributed power supply of the combination of the solar cell array 200 and the power conditioner 10. .

  One end and the other end of the capacitor C1 are electrically connected to the positive electrode terminal and the negative electrode terminal of the solar cell array 200 to smooth the DC voltage output from the solar cell array 200. The booster circuit 20 may be a so-called chopper type switching regulator. The booster circuit 20 boosts the voltage from the solar cell array 200. The booster circuit 20 may be configured by, for example, an insulation type booster circuit having a transformer winding such as a half bridge booster circuit or a full bridge booster circuit.

  The capacitor C2 smoothes the DC voltage output from the booster circuit 20. The inverter 40 includes a switch, and converts the DC voltage output from the booster circuit 20 into an AC voltage when the switch is turned on and off, and outputs the AC voltage to the system power supply 300 side. The inverter 40 may be configured, for example, by a single-phase full bridge PWM inverter including four semiconductor switches connected in a bridge. Among the four semiconductor switches, one pair of semiconductor switches is connected in series. The other pair of semiconductor switches among the four semiconductor switches are connected in series and connected in parallel with one pair of semiconductor switches.

  Between inverter 40 and system power supply 300, a coil L2 and a capacitor C3 are provided. Coil L2 and capacitor C3 remove noise from the AC voltage output from inverter 40. Further, a relay 50 is provided between the capacitor C3 and the system power supply 300. The relay 50 switches whether to cut off the inverter 40 and the system power supply 300 electrically. When the relay 50 is turned on, the power conditioner 10 and the system power supply 300 are electrically connected, and when the relay 50 is turned off, the power conditioner 10 and the system power supply 300 are electrically disconnected.

  Power conditioner 10 further includes voltage sensors 12, 16 and 22 and current sensors 14, 18 and 19. The voltage sensor 12 detects a voltage V1 corresponding to the potential difference between both ends of the solar cell array 200. The voltage sensor 16 detects a voltage V2 corresponding to the potential difference between both ends of the output side of the booster circuit 20. The voltage sensor 22 detects a voltage V3 corresponding to the potential difference between both ends of the output side of the inverter 40.

  The current sensor 14 detects the current I1 output from the solar cell array 200 and flowing to the input side of the booster circuit 20. The current sensor 18 detects the current I2 output from the booster circuit 20. The current sensor 19 detects a current I3 output from the inverter 40.

  Control device 100 boosts circuit 20 based on the voltages and currents detected by voltage sensors 12, 16 and 22 and current sensors 14, 18 and 19 so that maximum power can be obtained from solar cell array 200, and an inverter The switching operation of 40 is controlled to boost the DC voltage output from the solar cell array 200, convert the boosted DC voltage into an AC voltage, and output it to the system power supply 300 side.

  When the system power supply 300 is stopped, the power conditioner 10 configured as described above must turn off the relay 50 to electrically cut off the power conditioner 10 and the system power supply 300.

  Control device 100 includes an isolated operation detection unit 110, a relay control unit 150, and an output control unit 160. The isolated operation detection unit 110 is an example of an isolated operation detection device. The output control unit 160 adjusts reactive power from the power conversion unit by adjusting the phase difference between the phase of the current output from the inverter 40 and the phase of the voltage and the amplitude of the current output from the inverter 40. Make it output. The isolated operation detection unit 110 derives the target reactive power amount to be output from the power conversion unit via the output control unit 160, and provides the target reactive power amount to the output control unit 160. In addition, the isolated operation detection unit 110 detects the frequency fluctuation of the voltage of the system power supply 300 due to the supply of the reactive power to stop the system power supply 300, that is, the power conditioner 10 is operated alone. To detect When the isolated operation detection unit 110 detects that the power conditioner 10 is operated alone, the relay control unit 150 operates the relay 50 to electrically disconnect the power conditioner 10 from the system power supply 300.

  FIG. 2 is a functional block diagram of the isolated operation detection unit 110. As shown in FIG. The isolated operation detection unit 110 may be configured as an apparatus separate from the control device 100, and the isolated operation detection unit 110 may communicate with the control device 100 via a transmission cable. In this case, the control device 100 and the isolated operation detection unit 110 may be configured by a substrate and a microcomputer provided on the substrate. The substrate of the control device 100 and the substrate of the isolated operation detection unit 110 may have connectors, and the respective connectors may be connected via a transmission cable.

  The islanding operation detecting unit 110 includes a frequency measuring unit 112, a frequency deviation deriving unit 114, a first reactive energy deriving unit 116, a target reactive energy deriving unit 118, a voltage acquiring unit 120, a harmonic distortion deriving unit 122, and an islanding estimation. The unit 124 includes a reactive power adjustment unit 126, a voltage change amount deriving unit 128, a second reactive power derivation unit 130, and an isolated operation determination unit 132.

  The frequency measurement unit 112 acquires the voltage of the system power supply 300 via the voltage sensor 22, and measures the system frequency indicating the frequency of the system power supply 300 from the acquired voltage. The frequency measuring unit 112 measures, for example, a time difference between an intermediate value of falling and rising of the voltage signal detected from the voltage sensor 22 and an intermediate value of the next falling and rising as one cycle. When the system cycle of the system power supply 300 is 50 Hz (one system cycle is 20 ms), the measurement cycle of the system cycle may be 1/3 or less of the system cycle, for example, 5 ms.

  The frequency deviation deriving unit 114 derives the frequency deviation of the system power supply 300 based on the system frequency measured by the frequency measuring unit 112. The frequency deviation deriving unit 114 sequentially derives the moving average value of the system frequency for a predetermined moving average time based on the system frequency measured by the frequency measuring unit 112. The moving average time may be longer than one cycle of the system cycle, for example, 20 msec, and may be equal to or less than the time allowed from the single operation state to the detection of the single operation state. The moving average time may be, for example, less than 100 ms, and the moving average time may be, for example, 40 ms.

  The frequency deviation deriving unit 114 derives, as a frequency deviation, the difference between the latest moving average value and the moving average value in the past from the latest moving average value. The frequency deviation deriving unit 114 calculates the latest moving average value, which is the moving average value of each frequency from the frequency at the latest period measured by the frequency measuring unit 112 to the first predetermined number of periods earlier, The difference from the previous moving average value, which is the moving average value of each frequency from the latest period to the predetermined number of periods before the first period before the first time, is the frequency deviation It may be derived as

  For example, as shown in FIG. 3, the frequency deviation deriving unit 114 has a period (indicated by a reference numeral 400 in FIG. 3) which is a predetermined number before the frequency in the latest period measured by the frequency measuring unit 112. The latest moving average value, which is the moving average value of each frequency up to one cycle of the block, and each of the previous cycle 200 ms before the latest cycle to the predetermined 16 cycles before The difference from the past moving average value, which is a moving average value of frequency, may be derived as a frequency deviation. The frequency deviation deriving unit 114 may sequentially derive the frequency deviation every cycle that is the same as the measurement cycle of the system cycle, for example, every 5 msec.

  The first reactive energy derivation unit 116 derives the first reactive energy q1 based on the frequency deviation of the system power supply 300. The first reactive energy derivation unit 116 may derive the first reactive energy q1 so that the first reactive energy q1 increases in proportion to the frequency deviation of the grid power supply 300. For example, the first reactive energy derivation unit 116 may derive the reactive energy q1 corresponding to the frequency deviation with reference to the first reactive energy q1-frequency deviation characteristic as shown in FIG. 4.

  As shown in FIG. 4, when the variation of the frequency of the system power supply 300 is relatively small, ie, the frequency deviation is included in the first deviation range W1, and the frequency variation of the system power supply 300 is relatively large, ie, the frequency deviation The ratio of the reactive energy q1 to the magnitude of the frequency deviation may be changed in the case where the second deviation range W2 is included in the second deviation range W2. Further, when the frequency deviation is out of the first deviation range W1 and the second deviation range W2, the reactive energy q1 may be fixed to the first threshold reactive energy q1ta or -q1ta shown in FIG.

  Here, if the power conditioner 10 supplies reactive power to the system power supply 300 using the relatively large reactive power q1 when the power conditioner 10 is not operating alone, the power system may be adversely affected. There is. For example, when the frequency deviation is in the first deviation range W1, the power conditioner 10 often does not operate alone. Therefore, when the frequency deviation is included in the first deviation range W1, the first reactive energy derivation unit 116 may derive the reactive energy q1 so that the reactive energy q1 based on the frequency deviation becomes relatively small. .

  On the other hand, for example, when the reactive power output from the power conditioner 10 and the reactive power output from the load 310 are in a balanced state, the power conditioner 10 may be operating alone even when the frequency deviation is relatively small. There is sex.

  Therefore, even when the frequency deviation is relatively small, the power conditioner 10 performs so-called reactive power step injection if there is a possibility that the power conditioner 10 is operating alone. Power conditioner 10 further determines whether there is a possibility that power conditioner 10 is operating alone, using other electrical parameters other than frequency deviation. Then, when it is determined that there is a possibility that the power conditioner 10 is operating alone, the power conditioner 10 is a second reactive power amount that is additional to the first reactive power amount according to the frequency deviation. The reactive power obtained by adding the second reactive power q2 derived by the reactive power derivation unit 130 is output, and it is easy to detect that the power conditioner 10 is in an isolated operation even when the frequency deviation is relatively small. There is.

  The isolated operation estimation unit 124 determines whether the electrical parameter related to the power output from the system power supply 300 satisfies a predetermined electrical condition that the power conditioner 10 may be isolated. Then, it is determined whether there is a possibility that the power conditioner 10 is operating alone.

  The voltage acquisition unit 120 detects the voltage V3 of the system power supply 300 detected by the voltage sensor 22. The harmonic distortion deriving unit 122 derives a harmonic distortion voltage from the voltage information of the system power supply 300 detected by the voltage sensor 22. The harmonic distortion deriving unit 122 derives the harmonic distortion voltage of the system power supply 300, for example, by squaring each of the second to seventh harmonic distortion voltages and calculating the square root of their addition value. You may

  The isolated operation estimation unit 124 determines whether the electrical parameter related to the power output from the system power supply 300 satisfies the electrical condition that the power conditioner 10 may be isolated. Here, the electrical condition may be a fixed condition, or may be a variable condition according to a voltage detected by the power conditioner 10 or the like, an electric current, an electrical parameter such as frequency deviation, or the like. The isolated operation estimation unit 124 determines the power conditioner 10 based on the system voltage (fundamental wave voltage) of the system power supply 300 acquired by the voltage acquisition unit 120 or the harmonic distortion voltage derived by the harmonic distortion deriving unit 122. It is judged whether there is a possibility that is driving alone. The islanding operation estimation unit 124 may perform the islanding operation of the power conditioner 10 when the frequency deviation is in the first deviation range W1 and the fundamental wave voltage or the harmonic distortion voltage satisfies the predetermined electrical conditions. You may judge that there is sex.

  FIG. 5 is a flowchart showing a procedure of adding the second reactive energy q2 to the target reactive energy Q, that is, an example of a processing procedure of reactive power step injection.

  The isolated operation estimation unit 124 acquires the frequency deviation of the system power supply 300 from the frequency deviation derivation unit 114 (S100). The islanding operation estimation unit 124 determines whether or not the fundamental wave voltage fluctuates in advance with the frequency deviation within the first deviation range W1 (S102). When the voltage moves as shown in FIGS. 6A and 6B as shown in regions 501 and 502, it is determined that power conditioner 10 may be operating alone.

  Also, the islanding operation estimation unit 124 determines whether or not the harmonic distortion voltage has a predetermined fluctuation within the first deviation range W1 (S104). The islanding operation estimation unit 124 may have a possibility that the power conditioner 10 is in island operation, for example, when the harmonic distortion voltage moves in the regions 601 and 602 as shown in FIGS. 7A and 7B. I judge that there is.

  If the islanding operation estimation unit 124 determines that there is a possibility that the power conditioner 10 is operating alone, the second reactive power amount deriving unit 130 derives the second reactive power amount q2 and the target reactive power The amount deriving unit 118 adds the second reactive power q2 to the first reactive power q1 to derive a target reactive power Q (S106). The output control unit 160 outputs the reactive power output from the power conditioner 10 based on the target reactive power amount Q including the first reactive power amount q1 and the second reactive power amount q2 derived by the target reactive power amount deriving unit 118. Control.

  The second reactive energy derivation unit 130 ends the derivation of the second reactive energy q2 at a predetermined timing (S108). For example, when a predetermined time period has elapsed from the start of the derivation of the second reactive power q2, the second reactive power derivation unit 130 ends the derivation of the second reactive power q2. For example, when the number of times of deriving the second reactive power q2 reaches a predetermined number of times, the second reactive power derivation unit 130 ends the derivation of the second reactive power q2. The power conditioner 10 starts outputting the reactive power based on the target reactive power Q including the second reactive power q2, and then, after a predetermined period (for example, 200 ms) elapses, the second reactive power The output of reactive power based on the target reactive power amount Q including q2 is ended, and reactive power based on the target reactive power amount Q including only the first reactive power amount q1 according to the frequency deviation is output.

  In the second reactive power amount deriving unit 130, the power conversion unit may be operating alone in the electric parameter related to the power output from the system power supply 300 within the first deviation range W1 in which the frequency deviation is predetermined. A predetermined second reactive energy q2 used for islanding operation detection is sequentially derived over a predetermined period after it is determined that the predetermined electric condition is satisfied.

  When it is determined by the islanding operation estimation unit 124 that there is a possibility that the power conditioner 10 is in the islanding operation, the second reactive energy amount deriving unit 130 then determines a predetermined period, for example, 200 ms. Over time, a fixed amount of second reactive energy q2 is sequentially derived. The second reactive energy derivation unit 130 derives reactive energy when performing so-called reactive power step injection.

  The target reactive power amount deriving unit 118 calculates the first reactive power amount q1 sequentially derived by the target reactive power amount deriving unit 118, and the second reactive power amount when there is a possibility that the power conditioner 10 is operating alone. Based on the second reactive energy q2 derived by the deriving unit 130, the target reactive energy Q is derived. The target reactive energy derivation unit 118 derives the target reactive energy Q by adding the first reactive energy q1 and the second reactive energy q2. The target reactive energy derivation unit 118 provides the derived target reactive energy Q to the output control unit 160.

  The output control unit 160, for example, sets the inverter 40 so that maximum or maximum active power can be obtained from the solar cell array 200 based on the target active power P such that the maximum or maximum output can be obtained from the power conditioner 10. PWM control. Also, the output control unit 160 adjusts the phase difference between the phase of the current output from the inverter 40 and the phase of the voltage based on the target reactive power amount Q provided from the target reactive power amount deriving unit 118. Thus, the reactive power supplied to the system power supply 300 side is controlled.

  The reactive power output from the power conditioner 10 configured as described above causes a large fluctuation in the voltage supplied to the load 310, which may cause a so-called flicker phenomenon. For example, when a plurality of power conditioners 10 are installed under a pole transformer, or when a relatively large capacity power conditioner 10 is installed, or a pole transformer and a grid power supply 300 When the length of the connecting line is relatively long, reactive power supplied under the pole transformer causes voltage fluctuation, which may cause a flicker phenomenon.

  So, in this embodiment, when a plurality of power conditioners 10 are installed under a pole transformer, or when a relatively large capacity power conditioner 10 is installed, or a pole transformer and a grid Even when the length of the connecting line to the power supply 300 is relatively long, the flicker phenomenon is less likely to occur.

  In the power conditioner 10 according to the present invention, the temporal change in reactive energy when the frequency deviation changes in the convergence direction is temporal change in the reactive energy when the frequency deviation changes in the diverging direction Control reactive power output to be more gradual. In the power conditioner 10 according to the present invention, the temporal change in reactive energy when the frequency deviation gradually decreases is slower than the temporal change in reactive energy when the frequency deviation gradually increases. Control the reactive power output to be Thereby, the influence on the electric power system by the rapid change of the reactive power supplied to the system power supply 300 side is suppressed.

  When the frequency deviation changes in the diverging direction, there is a high possibility that the power conditioner 10 is operating alone, and it is necessary to detect the isolated operation of the power conditioner 10 immediately. On the other hand, when the frequency deviation changes in the convergence direction, the possibility that the power conditioner 10 is operating alone is relatively low. In the case where the frequency deviation is changing in the convergence direction, even if the temporal change of the reactive energy becomes gentle, the possibility of adversely affecting the isolated operation detection of the power conditioner 10 is low.

  According to the present embodiment, when the frequency deviation changes in the convergence direction, the temporal change of the reactive power amount is forcibly made gentle. As a result, the fluctuation of the reactive power does not increase, and flicker is less likely to occur. The influence on the electric power system due to the increase of the reactive power supplied to the system power supply 300 can be suppressed.

  The reactive power amount adjustment unit 126 sets the target ineffective power derived by the target reactive power amount derivation unit 118 at a predetermined timing after the frequency deviation is out of the predetermined deviation range, for example, the first deviation range. The reactive power adjustment A is executed as reactive power adjustment to adjust the target reactive power which the target reactive power deriving unit 118 derives so that the temporal change of the power becomes gentle. The reactive power amount adjustment unit 126 adjusts the target reactive power amount derived by the target reactive power amount derivation unit 118 so that the temporal change of the target reactive power amount derived by the target reactive power amount derivation unit 118 is gradual. The reactive power adjustment A may be performed by outputting the reactive power for adjustment such as ΔQth for adjusting the target reactive power as a command to the target reactive power deriving unit 118. The reactive energy adjustment unit 126 adjusts the reactive energy adjustment A when the frequency deviation changes in the convergence direction after the frequency deviation falls outside the predetermined deviation range, for example, the first deviation range W1. You may The reactive power amount adjustment unit 126 changes the temporal change of the target reactive power amount derived by the target reactive power amount derivation portion 118 when the frequency deviation is changing in the convergence direction, while the frequency deviation changes in the divergence direction. Reactive power adjustment A for adjusting the target reactive power derived by the target reactive power deriving unit 118 so that the target reactive power derived by the target reactive power deriving unit 118 is more gradual than the temporal change of the target reactive power when Run.

  The reactive energy adjustment unit 126 starts the reactive energy adjustment A, and then, after the frequency deviation falls within a predetermined deviation range, for example, the first deviation range W1, for a predetermined period, The reactive power adjustment A may be continued. After starting reactive power adjustment A, reactive power adjustment section 126 may continue reactive power adjustment A for a predetermined period.

  The reactive power amount adjustment unit 126 changes the frequency deviation in the convergence direction after the frequency deviation falls outside a predetermined deviation range, for example, the first deviation range W1 and a predetermined period (for example, 100 msec) elapses. If yes, reactive power adjustment A may be started. The conditions for starting the reactive power adjustment A may be determined based on the magnitude (amplitude) and the period of the reactive power output by the islanding operation detection unit 110.

  In the present embodiment, the reactive power amount is prevented from fluctuating following the voltage fluctuation due to the flicker. If the reactive power adjustment A can be continued over a period longer than the half cycle of the flicker, it is possible to prevent the reactive power from fluctuating following the voltage fluctuation due to the flicker. Therefore, the predetermined period may be determined based on at least one of the period and the size of the flicker generated in the voltage output from the system power supply 300. The predetermined period may be determined based on the half cycle of the flicker. A predetermined period may be determined such that the period for continuing the reactive power adjustment A is longer than the half cycle of the flicker. In addition, it is known that the frequency of the flicker which arises in the voltage which the system | strain power supply 300 outputs is 6-7 Hz, for example. That is, the half cycle of the flicker is, for example, about 72 msec to about 84 msec. Further, the predetermined period may be determined based on at least one of the magnitude (amplitude) and the period of the reactive power output from the islanding operation detection device.

  If the frequency deviation is changing in the convergence direction, and the frequency deviation derived by the frequency deviation deriving unit 114 is positive, the reactive energy amount adjusting unit 126 causes the frequency deviation deriving unit 114 to generate the first reactive energy. It is obtained by subtracting the previous target reactive energy Q (t−1) derived by the target reactive energy derivative 118 from the provisional current target reactive energy Q ′ (t) derived based on q1. If the change amount (Q '(t)-Q (t-1)) to be calculated is smaller than the first reference change amount (-.DELTA.Qth) determined in advance, the previous reactive power amount Q (t) The target reactive power amount deriving unit 118 derives the current target reactive power amount Q (t) based on the target reactive power amount Q (t−1) and the first reference change amount (−ΔQth) to obtain reactive power. Volume adjustment A may be performed. When the above-mentioned conditions are satisfied, the reactive energy adjustment unit 126 sets Q (t−1) −ΔQth as the current target reactive energy Q (t) to the target reactive energy derivation unit 118 and outputs the current target reactive energy Q. (T) may be derived.

  If the frequency deviation is changing in the convergence direction, and the frequency deviation derived by the frequency deviation deriving unit 114 is negative, the reactive energy amount adjusting unit 126 performs the first invalidation by the target reactive power amount deriving unit 118. The previous target reactive energy Q (t−1) derived by the target reactive energy derivative 118 is subtracted from the provisional current target reactive energy Q ′ (t) derived based on the energy q1. When the amount of change (Q ′ (t) −Q (t−1)) obtained by the above is larger than a predetermined second reference change amount ΔQth, the previous target is set as the current target reactive energy Q (t). Reactive power adjustment A may be performed by causing the target reactive power derivation unit 118 to derive the target reactive power at this time based on the reactive power Q (t−1) and the second reference change amount ΔQth. . If the reactive power amount adjustment unit 126 satisfies the above condition, the target reactive power amount derivation unit 118 sets the current target reactive power amount Q (Q (t−1) + ΔQth) as the current target reactive power amount Q (t). t) may be derived.

  When the frequency deviation is changing in the convergence direction, the reactive power adjustment unit 126 derives the target reactive power amount so that the target reactive power amount becomes zero over a predetermined duration (for example, 400 msec). The target amount of reactive power derived by the unit 118 may be adjusted. As a result, even when the reactive energy output from the power conditioner 10 is small, the reactive power output from the power conditioner 10 can be gradually reduced when the frequency deviation changes in the convergence direction.

  Here, immediately after the power conditioner 10 starts an isolated operation, the grid frequency measured by the frequency measurement unit 112 is unstable and the frequency deviation diverges after the frequency deviation goes out of the first deviation range W1. The frequency deviation may change in the convergence direction immediately after changing to. In such a case, if reactive power adjustment section 126 determines that the frequency deviation has changed in the convergence direction and executes reactive power adjustment A immediately, there is a possibility that the islanding operation can not be detected accurately. Then, after the frequency deviation falls outside a predetermined deviation range, for example, the first deviation range and the predetermined waiting period elapses, the reactive energy amount adjustment unit 126 changes the frequency deviation in the convergence direction. If so, reactive power adjustment A may be started.

  FIG. 8 and FIG. 9 are flowcharts showing an example of the derivation procedure of the target reactive power amount according to the present embodiment.

  The isolated operation estimation unit 124 acquires the frequency deviation of the system power supply 300 from the frequency deviation derivation unit 114 (S200). The islanding operation estimation unit 124 determines whether or not the fundamental wave voltage fluctuates in advance with the frequency deviation within the first deviation range W1 (S202). When the voltage moves as shown in FIGS. 6A and 6B as shown in regions 501 and 502, it is determined that power conditioner 10 may be operating alone.

  Also, the islanding operation estimation unit 124 determines whether or not the harmonic distortion voltage fluctuates in advance as the frequency deviation falls within the first deviation range W1 (S204). The islanding operation estimation unit 124 may have a possibility that the power conditioner 10 is in island operation, for example, when the harmonic distortion voltage moves in the regions 601 and 602 as shown in FIGS. 7A and 7B. I judge that there is.

  If the islanding operation estimation unit 124 determines that there is a possibility that the power conditioner 10 is operating alone, the second reactive power amount deriving unit 130 derives the second reactive power amount q2 and the target reactive power The amount deriving unit 118 adds the second reactive power q2 to the first reactive power q1 to derive a target reactive power Q (S206). The output control unit 160 outputs the reactive power output from the power conditioner 10 based on the target reactive power amount Q including the first reactive power amount q1 and the second reactive power amount q2 derived by the target reactive power amount deriving unit 118. Control.

  The second reactive energy derivation unit 130 ends the derivation of the second reactive energy q2 at a predetermined timing (S208). For example, the second reactive energy derivation unit 130 ends the derivation of the second reactive energy q2 when a predetermined time period has elapsed since the derivation of the second reactive energy q2 has been started.

  On the other hand, if the frequency deviation is outside the first deviation range W1 or the frequency deviation is within the first deviation range W1 and the fundamental wave voltage and the harmonic distortion voltage do not change in advance, that is, reactive power step injection is performed If not, the reactive energy adjustment unit 126 determines whether the frequency deviation is out of the first deviation range W1 (S210). The reactive energy amount adjustment unit 126 may perform the determination of S210 in parallel with the determination of S202 and S204 by the islanding operation estimation unit 124.

  If the frequency deviation is out of the first deviation range W1, the reactive energy adjustment unit 126 determines whether the predetermined transition period (for example, 100 msec) has passed after the frequency deviation becomes out of the first deviation range W1. It is determined whether or not (S212). If the transition period has not passed, the target reactive energy derivation unit 118 derives the target reactive energy Q based on the first reactive energy q1, as usual. The target reactive energy derivation unit 118 derives the temporary target reactive energy Q ′ derived based on the first reactive energy q1 as the current actual target reactive energy Q (t) (S214).

  On the other hand, if the transition period has passed, the reactive energy adjustment unit 126 determines whether the current frequency deviation derived by the frequency deviation deriving unit 114 is positive or negative (S300). If the frequency deviation is positive, the reactive energy adjustment unit 126 sets a value obtained by subtracting the previous actual target reactive energy Q (t−1) from the current provisional target reactive energy Q ′ (t) to 0. It is determined whether or not it is smaller. That is, the reactive energy adjustment unit 126 determines whether or not Q ′ (t) −Q (t−1) <0 is satisfied (S302). In step S302, the reactive energy adjustment unit 126 determines whether the frequency deviation has changed in the convergence direction. The reactive energy adjustment unit 126 determines that the frequency deviation changes in the convergence direction if Q ′ (t) −Q (t−1) <0 is satisfied. That is, the reactive energy adjustment unit 126 determines that the reactive energy has changed in the convergence direction if Q ′ (t) −Q (t−1) <0 is satisfied.

  If Q ′ (t) −Q (t−1) <0 is not satisfied, the reactive energy adjustment unit 126 determines that the frequency deviation is changing in the diverging direction, and the first reactive energy as usual. The target reactive energy derivation unit 118 is instructed to derive the target reactive energy Q based on q1. The target reactive energy derivation unit 118 derives the current temporary target reactive energy Q ′ derived based on the first reactive energy q1 as the current actual target reactive energy Q (t) (S304). .

  When Q ′ (t) −Q (t−1) <0 is satisfied, the reactive energy adjustment unit 126 determines that the first reference change amount (−−) where Q ′ (t) −Q (t−1) is predetermined. It is determined whether it is smaller than ΔQth (S306). That is, reactive power adjustment section 126 determines whether or not Q ′ (t) −Q (t−1) <− ΔQth is satisfied. When Q ′ (t) −Q (t−1) <− ΔQth is satisfied, the temporary target reactive energy Q ′ of this time based on the first reactive energy q 1 is invalid because the change of the reactive energy is too steep. The power amount adjustment unit 126 instructs the target reactive power amount deriving unit 118 to derive Q (t−1) −ΔQth as the actual target reactive power amount Q (t) of this time. In response to the instruction, the target reactive energy derivation unit 118 derives Q (t−1) −ΔQth as the actual target reactive energy Q (t) of this time (S308).

  On the other hand, if Q ′ (t) −Q (t−1) <− ΔQth is not satisfied, even if the reactive power amount is controlled with the present temporary target reactive power amount Q ′ based on the first reactive power amount q1, Since the change of the reactive power does not become steep, the reactive power adjustment unit 126 derives the target reactive power so as to derive the target reactive power Q (t) based on the first reactive power q1, as usual. It instructs the part 118. The target reactive energy derivation unit 118 derives the current provisional target reactive energy Q ′ (t) derived based on the first reactive energy q1 as the current actual target reactive energy Q (t). (S310).

  Next, the reactive energy adjustment unit 126 acquires the next frequency deviation derived by the frequency deviation deriving unit 114 (S312). The reactive energy adjustment unit 126 determines whether the acquired next frequency deviation is within the first deviation range W1.

  If the next frequency deviation is out of the first deviation range W1, the reactive energy adjustment unit 126 repeats the process of steps S306 to S312. That is, reactive power adjustment unit 126 continues reactive power adjustment A for adjusting the reactive power so that the change in reactive power does not become abrupt.

  On the other hand, if the next frequency deviation is within the first deviation range W1, the reactive energy adjustment unit 126 sets a timer (S316), and is determined in advance after the frequency deviation falls within the first deviation range W1. The reactive power adjustment A is further continued until the time passes.

  That is, after setting the timer, the reactive energy adjustment unit 126 determines whether or not the next frequency deviation satisfies Q ′ (t) −Q (t−1) <− ΔQth (S318). If Q ′ (t) −Q (t−1) <− ΔQth is satisfied, reactive power adjustment section 126 derives Q (t−1) −ΔQth as the actual target reactive power Q (t) of this time. The target reactive energy deriving unit 118 is instructed to cause the target reactive energy to In response to the instruction, the target reactive energy derivation unit 118 derives Q (t−1) −ΔQth as the current actual target reactive energy Q (t) (S320).

  On the other hand, if Q ′ (t) −Q (t−1) <− ΔQth is not satisfied, the reactive power adjustment unit 126 normally calculates the target reactive power Q (t) based on the first reactive power q1. The target reactive power amount deriving unit 118 is instructed to derive the The target reactive energy derivation unit 118 derives the current provisional target reactive energy Q ′ (t) derived based on the first reactive energy q1 as the current actual target reactive energy Q (t). (S310).

  After that, the reactive energy adjustment unit 126 determines whether or not the timer time has passed a predetermined time (S324). If the time has not elapsed, the reactive energy adjustment unit 126 further acquires the next frequency deviation (S326), and continues the processing after step S318. That is, reactive power adjustment unit 126 continues reactive power adjustment A. On the other hand, if the time has elapsed, reactive power adjustment section 126 stops reactive power adjustment A.

  As a result of the determination in step S300, when the frequency deviation is negative, the reactive power adjustment unit 126 determines the previous actual target reactive power Q (t-1) from the current provisional target reactive power Q '(t). It is determined whether the value obtained by subtracting is larger than 0 or not. That is, the reactive energy adjustment unit 126 determines whether or not Q ′ (t) −Q (t−1)> 0 is satisfied (S330). The reactive energy adjustment unit 126 also determines in step S330 whether the frequency deviation has changed in the convergence direction. The reactive energy adjustment unit 126 determines that the frequency deviation has changed in the convergence direction if Q ′ (t) −Q (t−1)> 0 is satisfied. That is, the reactive energy adjustment unit 126 determines that the reactive energy is changing in the convergence direction if Q ′ (t) −Q (t−1)> 0 is satisfied.

  If Q ′ (t) −Q (t−1)> 0 is not satisfied, the reactive power adjustment unit 126 determines that the frequency deviation is changing in the diverging direction, and the first reactive power as usual. The target reactive energy derivation unit 118 is instructed to derive the target reactive energy Q based on q1. The target reactive energy derivation unit 118 derives the current temporary target reactive energy Q ′ derived based on the first reactive energy q1 as the current actual target reactive energy Q (t) (S332) .

  When Q ′ (t) −Q (t−1)> 0 is satisfied, the reactive energy adjustment unit 126 sets Q ′ (t) −Q (t−1) to a second reference change amount (ΔQth) determined in advance. ) Is determined (S334). That is, reactive power adjustment section 126 determines whether or not Q ′ (t) −Q (t−1)> ΔQth is satisfied. If Q ′ (t) −Q (t−1)> ΔQth, the temporary target reactive energy Q ′ based on the first reactive energy q1 has too steep a change in reactive energy, so reactive power The amount adjustment unit 126 instructs the target reactive power amount deriving unit 118 to derive Q (t−1) + ΔQth as the actual target reactive power amount Q (t) of this time. In response to the instruction, the target reactive energy derivation unit 118 derives Q (t−1) + ΔQth as the current actual target reactive energy Q (t) (S336).

  On the other hand, if Q ′ (t) −Q (t−1)> ΔQth is not satisfied, even if the reactive power amount is controlled with the current provisional target reactive power amount Q ′ based on the first reactive power amount q1, the reactive power amount is invalid. Since the change in the power amount does not become steep, the reactive power amount adjustment unit 126 normally derives the target reactive power amount deriving unit to derive the target reactive power amount Q (t) based on the first reactive power amount q1. Indicate at 118. The target reactive energy derivation unit 118 derives the current provisional target reactive energy Q ′ (t) derived based on the first reactive energy q1 as the current actual target reactive energy Q (t). (S338).

  Next, the reactive energy adjustment unit 126 acquires the next frequency deviation derived by the frequency deviation deriving unit 114 (S340). The reactive energy adjustment unit 126 determines whether the acquired next frequency deviation is within the first deviation range W1.

  If the next frequency deviation is out of the first deviation range W1, the reactive energy adjustment unit 126 repeats the processing of step S334 to step S340. That is, reactive power adjustment unit 126 continues reactive power adjustment A for adjusting the reactive power so that the change in reactive power does not become abrupt.

  On the other hand, if the next frequency deviation is within the first deviation range W1, the reactive energy adjustment unit 126 sets a timer (S344), and is determined in advance after the frequency deviation falls within the first deviation range W1. The reactive power adjustment A is further continued until the time passes.

  That is, after setting the timer, the reactive energy adjustment unit 126 determines whether or not the next frequency deviation satisfies Q ′ (t) −Q (t−1)> ΔQth (S346). If Q ′ (t) −Q (t−1)> ΔQth is satisfied, reactive power adjustment unit 126 derives Q (t−1) + ΔQth as the actual target reactive power Q (t) of this time. To the target reactive energy derivation unit 118. In response to the instruction, the target reactive energy derivation unit 118 derives Q (t−1) + ΔQth as the current actual target reactive energy Q (t) (S348).

  On the other hand, if Q ′ (t) −Q (t−1)> ΔQth is not satisfied, the reactive energy adjustment unit 126 calculates the target reactive energy Q (t) based on the first reactive energy q1 as usual. It instructs the target reactive power amount deriving unit 118 to derive it. The target reactive energy derivation unit 118 derives the current provisional target reactive energy Q ′ (t) derived based on the first reactive energy q1 as the current actual target reactive energy Q (t). (S350).

  Thereafter, the reactive energy adjustment unit 126 determines whether or not the timer time has elapsed in advance (S352). If the time has not elapsed, the reactive energy adjustment unit 126 further acquires the next frequency deviation (S354), and continues the processing after step S346. That is, reactive power adjustment unit 126 continues reactive power adjustment A. On the other hand, if the time has elapsed, reactive power adjustment section 126 stops reactive power adjustment A.

  As described above, according to the above-described procedure, the power conditioner 10 is ineffective when the temporal variation of the reactive energy when the frequency deviation is changing in the convergence direction is changing the frequency deviation in the diverging direction. It is possible to control the output of reactive power so as to be slower than the temporal change of electric energy.

  FIG. 10 is a flowchart showing another example of the procedure for deriving the target reactive energy according to the present embodiment.

  In FIG. 9, the example which continues reactive power adjustment adjustment A until a predetermined time passes, after a frequency deviation enters in the 1st deviation range W1, was demonstrated. On the other hand, in FIG. 10, reactive power adjustment A is continued until a predetermined time elapses after the frequency deviation starts to change in the convergence direction.

  That is, when the frequency deviation is positive, the reactive energy adjustment unit 126 determines whether or not Q ′ (t) −Q (t−1) <0 is satisfied (S302), Q ′ (t) −. If Q (t-1) <0 is satisfied, it is determined that the frequency deviation has started to change in the convergence direction, and a timer is set (S318). Then, the reactive power amount adjustment unit 126 continues the reactive power amount adjustment A until the timer time passes a predetermined time, as in the procedure shown in FIG.

  On the other hand, when the frequency deviation is negative, the reactive energy adjustment unit 126 determines whether or not Q ′ (t) −Q (t−1)> 0 is satisfied (S330), Q ′ (t) − If Q (t-1)> 0 is satisfied, it is determined that the frequency deviation has started to change in the convergence direction, and the timer is set (S344). Then, the reactive power amount adjustment unit 126 continues the reactive power amount adjustment A until the timer time passes a predetermined time, as in the procedure shown in FIG.

  As described above, according to the above procedure, when the frequency deviation is changing in the convergence direction, the change in reactive energy can be made gentler than in the case where the frequency deviation is changing in the divergence direction. Thereby, when a plurality of power conditioners 10 are installed under the pole transformer, or when a relatively large capacity power conditioner 10 is installed, or between the pole transformer and the grid power supply 300 Even when the length of the connecting line is relatively long, the flicker phenomenon can be less likely to occur.

  For example, when the frequency deviation is changing in the convergence direction, there is no restriction on the rate of change of the reactive energy, that is, even when the frequency deviation is moving in the convergence direction, the frequency deviation corresponds to the magnitude. When the power conditioner 10 controls the reactive power in accordance with the target reactive power, as shown in FIG. 11, the reactive power may also fluctuate in a short cycle in conjunction with the flicker cycle. On the other hand, in the case where the rate of change in reactive power is limited when the frequency deviation changes in the convergence direction, the reactive power does not fluctuate in a short cycle in conjunction with the flicker cycle. In the case where the upper limit is given to the temporal change of the target reactive energy to make the power conditioner 10 control the change of the reactive energy when the frequency deviation is changing in the convergence direction, the reactive power is interlocked with the flicker cycle. The amount does not fluctuate in short cycles. Thus, when the power conditioner 10 is not operating alone, as shown in FIG. 12, the reactive energy converges normally. Thus, it is possible to prevent the reactive power from being continuously output even though the power conditioner 10 is not operating alone.

  As described above, in the above, when the frequency deviation is changing in the convergence direction, the reactive power adjustment unit 126 temporally changes the target reactive power derived by the target reactive power deriving unit 118 but the frequency deviation diverges. The target reactive power amount derived by the target reactive power amount deriving unit 118 is adjusted such that the target reactive power amount derived by the target reactive power amount derivation unit 118 becomes slower than the temporal change of the target reactive power amount when changing in the direction. An example has been described.

  Subsequently, an example will be described in which the reactive power is prevented from fluctuating in conjunction with the flicker by adjusting the target reactive power amount according to the magnitude of the change of the voltage of the system power supply 300. As the magnitude of the voltage change amount of the grid voltage of the system power supply 300 acquired by the voltage acquisition unit 120 increases, the reactive power adjustment unit 126 sets the target reactive power amount derived by the target reactive power derivation unit 118. The reactive energy adjustment B is performed to adjust the target reactive energy derived by the target reactive energy derivation unit 118 so that the temporal change becomes gentle.

  FIG. 13 is a flowchart showing an example of a procedure for adjusting the target reactive power amount in accordance with the voltage change amount.

  The first reactive energy derivation unit 116 acquires the frequency deviation Δf derived by the frequency deviation derivation unit 114 (S400). The reactive power amount adjustment unit 126 acquires the voltage change amount ΔV of the voltage of the system power supply 300 derived by the voltage change amount derivation unit 128 (S402). The first reactive energy derivation unit 116 refers to, for example, a first reactive energy q1-frequency deviation characteristic as shown in FIG. 4 based on the frequency deviation, and generates the reactive energy q1 corresponding to the frequency deviation .DELTA.f. It derives (S404). Based on the voltage change amount ΔV, the reactive power amount adjustment unit 126 adjusts the temporal change of the target reactive power amount derived by the target reactive power amount derivation portion 118 as the voltage change amount ΔV becomes larger. The adjusted reactive energy qa is derived (S406).

  The reactive power adjustment unit 126 may derive the adjusted reactive power qa corresponding to the voltage change amount ΔV, for example, with reference to the adjusted reactive power amount qa-voltage change amount ΔV characteristics as shown in FIG. As shown in FIG. 14, as the voltage change amount ΔV increases in the positive direction, the adjustment reactive power amount qa increases in the negative direction so that the change in the target reactive power amount decreases. On the other hand, the adjustment reactive power amount qa increases in the positive direction so that the change in the target reactive power decreases as the voltage change amount ΔV increases in the negative direction.

  The adjusted reactive energy qa may have an upper limit value and a lower limit value as shown in FIG. When the voltage change amount ΔV is larger than the predetermined first reference voltage change amount ΔVth1, the lower limit value qath1 may be constant. In the case where the voltage change amount ΔV is smaller than the predetermined second reference voltage change amount ΔVth2, the upper limit value qath2 may be constant.

  Further, the reactive power adjustment unit 126 derives the adjusted reactive power qa corresponding to the voltage change amount ΔV with reference to, for example, the adjusted reactive power amount qa-voltage change amount ΔV characteristics as shown in FIG. Good. According to the adjustment reactive energy qa-voltage change amount ΔV characteristic shown in FIG. 15, in the voltage change amount range corresponding to the third deviation range W3 indicating the range of the predetermined frequency deviation, according to the voltage change amount ΔV , Target reactive energy is not adjusted.

  Next, the reactive power amount adjustment unit 126 instructs the target reactive power amount derivation unit 118 to adjust the target reactive power amount based on the adjusted reactive power amount qa. The target reactive energy derivation unit 118 derives a target reactive energy Q based on the first reactive energy q1 and the adjusted reactive energy qa (S408).

  When the voltage change amount ΔV is within a predetermined voltage change amount range (that is, ΔV is in the range of ΔVth2 to ΔVth1), the reactive power amount adjustment unit 126 adjusts the adjustment reactive power amount qa based on the voltage change amount ΔV. Reactive power adjustment B may be performed by deriving and causing the target reactive power derivation unit 118 to derive the current target reactive power Q based on the first reactive power q1 and the adjusted reactive power qa. .

  On the other hand, when the voltage change amount ΔV is out of the voltage change amount range (that is, ΔV is in the range of ΔVth2 to ΔVth1), the reactive power amount adjustment unit 126 determines that the predetermined reference adjustment reactive power (ΔVth1 or ΔVth2) The reactive power adjustment B may be performed by causing the target reactive power amount deriving unit 118 to derive the target reactive power amount Q based on the first reactive power amount q1.

  As described above, according to the above-described example, by adjusting the target reactive power amount in accordance with the magnitude of the change in the voltage of the system power supply 300, it is possible to prevent the reactive power from fluctuating in conjunction with the flicker.

  Furthermore, another example of adjusting the target reactive power amount in accordance with the magnitude of the change in the voltage of the system power supply 300 will be described.

  In another example, the reactive energy adjustment unit 126 adjusts the target reactive energy by narrowing down when the possibility of voltage fluctuation due to flicker is high.

  FIG. 16 shows an example of a functional block of the reactive energy adjustment unit 126 according to another example. The reactive energy adjustment unit 126 includes a frequency deviation acquisition unit 1261, a band pass filter unit 1262, a voltage change amount acquisition unit 1263, a band pass filter unit 1264, a correlation function derivation unit 1265, and an adjustment reactive energy derivation unit 1266.

  The frequency deviation acquisition unit 1261 acquires the frequency deviation Δf derived by the frequency deviation derivation unit 114. The band pass filter unit 1262 extracts only the frequency deviation Δf that changes in a cycle equivalent to the flicker cycle. The band pass filter unit 1262 extracts only the frequency deviation Δf that changes in a cycle range determined based on the flicker cycle generated in the voltage output from the system power supply 300.

  The voltage change amount acquisition unit 1263 acquires the voltage change amount ΔV of the voltage of the system power supply 300 derived by the voltage change amount derivation unit 128. The band pass filter unit 1264 extracts only the voltage change amount ΔV that changes in a cycle equivalent to the flicker cycle. The band pass filter unit 1264 extracts only the voltage change amount ΔV that changes in a cycle range determined based on the flicker cycle generated in the voltage output from the system power supply 300.

  The correlation function deriving unit 1265 derives a correlation function indicating the correlation between the frequency deviation Δf and the voltage change amount ΔV. Even when the power conditioner 10 is not operating alone, flicker may occur due to the influence of reactive power or the like, and the voltage of the system power supply 300 may periodically fluctuate. It is desirable that the amount of reactive power does not fluctuate under the influence of such flicker. When flicker occurs, the voltage fluctuation and the system frequency fluctuation are in synchronization. Therefore, when the flicker occurs, the frequency deviation Δf and the voltage change amount ΔV are in synchronization with each other. Therefore, the correlation between the frequency deviation Δf and the voltage change amount ΔV shows high similarity. That is, the value indicated by the correlation between the frequency deviation Δf and the voltage change amount ΔV shows a value close to one. In this case, when the target reactive power is derived only by the frequency deviation Δf, the reactive power output from the power conditioner 10 fluctuates due to the influence of the flicker.

  Therefore, the adjusted reactive energy derivation unit 1266 executes reactive energy adjustment B in accordance with the value indicated by the correlation function derived by the correlation function deriving unit 1265. The adjusted reactive energy derivation unit 1266 causes the change in the target reactive energy derived by the target reactive energy derivation unit 118 to be gradual as the value indicated by the correlation function derived by the correlation function deriving unit 1265 increases. Then, the adjusted reactive power amount qa may be derived.

  The adjusted reactive energy derivation unit 1266 may execute reactive energy adjustment B when the value indicated by the correlation function derived by the correlation function deriving unit 1265 is equal to or greater than a predetermined threshold. The adjusted reactive energy derivation unit 1266 provisionally derives the adjusted reactive energy qa ′ based on the adjusted reactive energy qa-voltage change amount ΔV characteristic shown in FIG. 14 or FIG. The adjustment reactive power amount qa may be derived by multiplying 'by a coefficient proportional to the value of the correlation function.

  The correlation function deriving unit 1265 performs filtering by the band pass filter unit 1262 and the band pass filter unit 1264 to change the frequency deviation Δf that changes in a cycle range determined based on the flicker cycle generated in the voltage output from the system power supply 300. A correlation function may be derived for the voltage change amount ΔV.

  The target reactive energy derivation unit 118 generates a target based on the first reactive energy q1 derived by the first reactive energy derivation unit 116 and the adjusted reactive energy qa derived by the adjusted reactive energy derivation unit 1266. The reactive energy adjustment B is performed by causing the reactive energy derivation unit 118 to derive the target reactive energy Q at this time.

  FIG. 17 is a flowchart illustrating another example of the procedure for adjusting the target reactive power amount in accordance with the voltage change amount.

  The first reactive energy derivation unit 116 acquires the frequency deviation Δf derived by the frequency deviation derivation unit 114 (S500). The first reactive energy derivation unit 116 refers to, for example, the first reactive energy q1-frequency deviation characteristic as shown in FIG. 4 based on the frequency deviation .DELTA.f, and determines the reactive energy q1 corresponding to the frequency deviation .DELTA.f. Are derived (S502).

  The reactive power amount adjustment unit 126 acquires the voltage change amount ΔV of the voltage of the system power supply 300 derived by the voltage change amount derivation unit 128 (S 504). The reactive energy adjustment unit 126 derives a correlation function that indicates the correlation between the frequency deviation Δf and the voltage change amount ΔV (S506).

  Next, the reactive energy adjustment unit 126 determines whether the value indicated by the correlation function is equal to or greater than a threshold (S508). If the value indicated by the correlation function is smaller than the threshold value, that is, if the correlation between the frequency deviation Δf and the voltage change amount ΔV is low, it is less likely that the system voltage and the system frequency are fluctuating due to the influence of flicker. . Therefore, when the value indicated by the correlation function is smaller than the threshold, the reactive energy adjustment unit 126 does not provide the adjusted reactive energy qa to the target reactive energy derivation unit 118, and the target reactive energy derivation unit 118 does not A target reactive power amount is derived based on the reactive power amount q1 (S514). When the second reactive energy derivation unit 130 supplies the second reactive energy q2, the target reactive energy derivation unit 118 is based on the first reactive energy q1 and the second reactive energy q2. The target reactive energy may be derived.

  If the value indicated by the correlation function is equal to or greater than the threshold value, there is a possibility that the grid voltage and the grid frequency are fluctuating due to the influence of flicker, so the reactive power adjustment part 126 adjusts based on the voltage change amount ΔV. The reactive energy qa is derived (S510). The reactive energy adjustment unit 126 may further adjust the adjustment reactive energy qa according to the value indicated by the correlation function. The reactive energy adjustment unit 126 multiplies the temporary adjustment reactive energy qa ′ derived based on the voltage change amount ΔV by a coefficient proportional to the magnitude of the value indicated by the correlation function to obtain the actual adjustment reactive power. The quantity qa may be derived.

  The adjusted reactive energy qa derived by the reactive energy adjustment unit 126 is provided to the target reactive energy derivation unit 118, and the target reactive energy derivation unit 118 generates the first reactive energy q1 and the adjusted reactive energy qa. The target reactive energy Q is derived based on (S512). The target reactive power amount deriving unit 118 may derive the target reactive power amount Q by adding the first reactive power amount q1 and the adjustment reactive power amount qa. When the second reactive energy derivation unit 130 is providing the second reactive energy q2, the target reactive energy derivation unit 118 adjusts the first reactive energy q1, the second reactive energy q2, and the adjustment. The target reactive power may be derived based on the reactive power qa. When the second reactive energy derivation unit 130 is providing the second reactive energy q2, the target reactive energy derivation unit 118 generates the first reactive energy q1, the second reactive energy q2, and the adjusted reactive energy. The target reactive energy may be derived by adding the amount qa.

  As described above, according to the above procedure, according to the magnitude of the voltage change of the system power supply 300, when the voltage change of the system power supply 300 is caused due to flicker instead of the single operation of the power conditioner 10. , Adjust the target reactive energy. Thereby, it is possible to prevent the reactive power from fluctuating in conjunction with the flicker.

  In the above, reactive power adjustment A and reactive power adjustment B have been described independently. However, the reactive energy adjustment unit 126 may execute reactive energy adjustment A and reactive energy adjustment B in parallel. That is, the reactive power adjustment unit 126 may execute the reactive power adjustment A and the reactive power adjustment B in combination.

  Further, the reactive power adjustment unit 126 reduces the conversion gain of the first reactive power derivation unit 116 so that the magnitude of the output of the target reactive power derived by the target reactive power derivation unit 126 is reduced. The reactive power adjustment A may be performed by adjusting to. For example, the reactive energy adjustment unit 126 changes the function indicating the relationship between the frequency deviation and the first reactive energy q1 to obtain the first reactive energy q1 derived by the first reactive energy derivation unit 116. The reactive power adjustment A may be performed by adjusting the temporal change to be gentle.

  For example, in a first function having a first slope indicating a relationship between the frequency deviation Δf and the first reactive energy q1 within the second deviation range as shown in FIG. The first reactive energy is derived based on the above. In this case, the reactive energy adjustment unit 126 derives the first reactive energy q1 to the first reactive energy derivation unit 116 based on a second function having a second slope smaller than the first slope within the second deviation range. Reactive power adjustment A may be performed by performing the above operation. The second inclination may be a fixed inclination, or may be a variable inclination in accordance with a voltage detected by the power conditioner 10 or the like, an electric current, an electrical parameter such as frequency deviation, or the like. Further, the reactive power control unit 126 may suppress the first reactive power q1 derived by the first reactive power derivation unit 116 by adjusting the frequency deviation derived by the frequency deviation deriving unit 114. .

  Further, the reactive energy adjustment unit 126 causes the frequency deviation deriving unit 114 to adjust the frequency deviation so that the frequency deviation derived by the frequency deviation deriving unit 114 becomes smaller, and the first reactive power is adjusted based on the adjusted frequency deviation. The reactive energy adjustment A may be performed by causing the amount deriving unit 116 to derive the first reactive energy q1.

  The frequency deviation deriving unit 114 receives the adjustment command from the reactive energy amount adjusting unit 126, derives the past moving average value using each frequency of a larger number of cycles than usual, and the frequency deviation becomes smaller. You may adjust to For example, as shown in FIG. 18A, the frequency deviation deriving unit 114 uses a third number (the number is larger than the second number (16)) from the past period of 200 ms before predetermined as the past moving average value from the latest period. The reactive power adjustment A may be performed by deriving the frequency deviation from the difference between the moving average value of each frequency up to the cycle 32) minutes ago and the latest moving average value. The third number may be a fixed value, or may be a variable value according to a voltage detected by the power conditioner 10 or the like, an electric current, an electrical parameter such as frequency deviation, or the like.

  By using the moving average value of the frequency over a period longer than usual, since the moving average value is more averaged, the frequency deviation can be reduced. Therefore, when the first reactive energy derivation unit 116 derives the first reactive energy q1 using the frequency deviation derived in this manner, it is derived based on the first reactive energy q1 as a result. Changes in target reactive energy over time.

  Further, in order to reduce the frequency deviation, the frequency deviation deriving unit 114 receives an adjustment command from the reactive energy adjustment unit 126, and as shown in FIG. 18B, determines in advance from the latest period as the past moving average value. The moving average value of each frequency from the past period before the second time (10 ms) which is shorter than the first time (200 ms) to the period before the second number (eight) minutes, the latest moving average and The reactive power adjustment A may be performed by deriving the frequency deviation from the difference of The second time may be a fixed time, or may be a variable time according to a voltage detected by the power conditioner 10 or the like, an electric current, an electrical parameter such as a frequency deviation, or the like.

  By using the frequency measured in a period relatively close to the frequency used for deriving the latest moving average value as the frequency used for deriving the moving average value in the past, the frequency deviation derived by the frequency deviation deriving unit 114 can be obtained. It can be made smaller. Therefore, as the frequency used for deriving the moving average in the past, by using the frequency measured in a period relatively close to the frequency used for deriving the latest moving average, as a result, the first amount of reactive energy q1 Changes in the target reactive energy derived on the basis of

  Note that each unit included in the control device 100 according to the present embodiment installs a program recorded in a computer readable recording medium that performs various processes related to control of active power and reactive power of the power conditioner 10, and this program May be configured to be executed by a computer. That is, even if the control device 100 is configured by causing the computer to function as each unit included in the control device 100 by causing the computer to execute a program that performs various processes related to control of active power and reactive power of the power conditioner 10 Good.

  The computer has various memories such as a CPU, ROM, RAM, EEPROM (registered trademark), a communication bus, and an interface, and the control device 100 reads out processing programs stored in the ROM beforehand as firmware and sequentially executes them. Act as.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It is apparent to those skilled in the art that various changes or modifications can be added to the above embodiment. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the present invention.

  The execution order of each process such as operations, procedures, steps, and steps in the apparatuses, systems, programs, and methods shown in the claims, the specification, and the drawings is particularly “before”, “preceding” It is to be noted that “it is not explicitly stated as“ etc. ”and can be realized in any order as long as the output of the previous process is not used in the later process. With regard to the flow of operations in the claims, the specification and the drawings, even if it is described using “first,” “next,” etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 1 Power supply system 10 Power conditioners 12, 16, 22 Voltage sensors 14, 18, 19 Current sensor 20 Step-up circuit 40 Inverter 50 Relay 100 Control device 110 Individual operation detection unit 112 Frequency measurement unit 114 Frequency deviation derivation unit 116 First reactive power Amount deriving unit 118 Target reactive energy deriving unit 120 Voltage acquiring unit 122 Harmonic distortion deriving unit 124 Isolated operation estimating unit 126 Reactive energy adjusting unit 128 Voltage variation deriving unit 130 Reactive energy deriving unit 132 Isolated operation determining unit 150 Relay Control unit 160 Output control unit 200 Solar cell array 300 System power supply 310 Load 1261 Frequency deviation acquisition unit 1262, 1264 Band pass filter unit 1263 Voltage change acquisition unit 1265 Correlation function derivation unit 1266 Adjustment reactive energy amount derivation unit

Claims (30)

An islanding operation detection device for detecting an islanding operation of a power conversion unit connected to an AC power supply, comprising:
A frequency deviation deriving unit that derives a frequency deviation of the AC power supply;
A first reactive power amount deriving unit that derives a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived by the frequency deviation deriving unit;
A voltage change amount deriving unit that derives a voltage change amount of the voltage output from the power conversion unit;
A target reactive power amount deriving unit for deriving a target reactive power amount to be output by the power conversion unit for the islanding operation detection based on the first reactive power amount derived by the first reactive power amount deriving unit When,
A reactive power adjustment unit that executes a first reactive power adjustment that adjusts the target reactive power that the target reactive power derivation unit derives based on the magnitude of the voltage change amount ;
A voltage change amount acquisition unit that acquires a voltage change amount of a voltage output from the AC power supply;
A correlation function deriving unit that derives a correlation function indicating a correlation between the frequency deviation and the voltage change amount ,
The islanding operation detecting device , wherein the reactive power amount adjustment unit executes the first reactive power amount adjustment according to a value indicated by the correlation function derived by the correlation function deriving unit .   The reactive power amount adjustment unit is a target derived by the target reactive power amount deriving unit based on the voltage change amount changing in a cycle range determined based on a flicker cycle occurring in a voltage output from the AC power supply. The islanding operation detection device according to claim 1, wherein the first reactive power adjustment is performed by adjusting the reactive power.   The reactive power adjustment unit is configured to adjust the target reactive power such that temporal change in the target reactive power derived by the target reactive power deriving unit becomes gradual as the magnitude of the voltage change increases. The islanding operation detection device according to claim 1, wherein the first reactive power adjustment is performed by adjusting a target reactive power that the amount deriving unit derives. The correlation function deriving unit, for said frequency deviation and the voltage change amount varies with a period range determined based on the period of the flicker generated in voltages the AC power supply is output to derive said correlation function, according to claim 1 The islanding detection device according to any one of 3 . The reactive power amount adjustment unit derives the adjusted reactive power amount based on the voltage change amount, and the target reactive power amount deriving unit determines the target of the current reactive power amount based on the first reactive power amount and the adjusted reactive power amount. The islanding operation detection device according to any one of claims 1 to 4 , wherein the first reactive power adjustment is performed by deriving the reactive power. When the voltage change amount is within a predetermined voltage change amount range, the reactive power amount adjustment unit derives an adjustment reactive power amount based on the voltage change amount, and adjusts the first reactive power amount and the adjustment. The islanding operation detection device according to claim 5 , wherein the first reactive power adjustment is performed by causing the target reactive power derivation unit to derive the target reactive power amount based on the reactive power amount. When the voltage change amount is out of the voltage change amount range, the reactive power amount adjustment unit is configured to derive the target reactive power amount based on a predetermined reference adjustment reactive power amount and the first reactive power amount. The islanding operation detection device according to claim 6 , wherein the first reactive power amount adjustment is performed by causing the second reactive power amount to be derived this time. The reactive power adjustment unit changes temporally the target reactive power derived by the target reactive power deriving unit at a predetermined timing after the frequency deviation falls outside a predetermined deviation range. The islanding operation detection method according to any one of claims 1 to 7 , further performing a second reactive power adjustment that adjusts the target reactive power that the target reactive power derivation unit derives so that the target reactive power becomes gentle. apparatus. An islanding operation detection device for detecting an islanding operation of a power conversion unit connected to an AC power supply, comprising:
  A frequency deviation deriving unit that derives a frequency deviation of the AC power supply;
  A first reactive power amount deriving unit that derives a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived by the frequency deviation deriving unit;
  A voltage change amount deriving unit that derives a voltage change amount of the voltage output from the power conversion unit;
  A target reactive power amount deriving unit for deriving a target reactive power amount to be output by the power conversion unit for the islanding operation detection based on the first reactive power amount derived by the first reactive power amount deriving unit When,
  A reactive power adjustment unit that executes a first reactive power adjustment to adjust a target reactive power derived by the target reactive power deriving unit based on the magnitude of the voltage change amount;
Equipped with
  The reactive power adjustment unit changes temporally the target reactive power derived by the target reactive power deriving unit at a predetermined timing after the frequency deviation falls outside a predetermined deviation range. The islanding operation detection device, which further executes a second reactive power adjustment that adjusts the target reactive power that the target reactive power derivation unit derives so that the second reactive power becomes moderate. The islanding operation according to claim 8 or 9, wherein the reactive power amount adjustment unit continues the second reactive power amount adjustment for a predetermined period after starting the second reactive power amount adjustment. Detection device. The reactive power amount adjustment unit starts the second reactive power amount adjustment, and then, after the frequency deviation falls within a predetermined deviation range, the second reactive power is maintained for a predetermined period. The islanding detection device according to claim 8 or 9, wherein the amount adjustment is continued.   The islanding operation detection device according to claim 10, wherein the predetermined period is determined based on at least one of a cycle and a magnitude of flicker generated in a voltage output from the AC power supply.   The islanding operation detection device according to claim 10, wherein the predetermined period is determined based on at least one of a magnitude and a cycle of reactive power output from the islanding operation detection device. 14. The reactive power amount adjustment unit according to claim 8 , wherein the second reactive power amount adjustment is started after the frequency deviation is out of a predetermined deviation range and a predetermined standby period elapses. The islanding detection device according to any one. Conditions for starting the second reactive energy adjustment of the reactive power amount adjusting section, the isolated operation detecting apparatus is determined based on the size and period of the reactive power to be output, any one of claims 8 13 1 Islanding detection device described in the above. When the frequency deviation derived by the frequency deviation deriving unit is positive, the reactive power amount adjusting unit is a provisional current target derived based on the first reactive energy by the target reactive power deriving unit. If the amount of change obtained by subtracting the previous target reactive power derived by the target reactive power deriving unit from the amount of reactive power is smaller than the first reference change amount, the current target reactive power as the current reactive power. The second reactive power adjustment is performed by causing the target reactive power derivation unit to derive a current target reactive power based on the previous target reactive power and the first reference change amount. The islanding detection device according to any one of claims 8 to 15. When the frequency deviation derived by the frequency deviation deriving unit is negative, the reactive power amount adjusting unit is a provisional current target derived based on the first reactive energy by the target reactive power deriving unit. When the amount of change obtained by subtracting the previous target reactive power derived by the target reactive power deriving unit from the amount of reactive power is larger than the second reference change amount, the above-mentioned target reactive power as the current target reactive power is The second reactive power adjustment is performed by causing the target reactive power derivation unit to derive the current target reactive power based on the previous target reactive power and the second reference change amount. The islanding detection device according to any one of claims 8 to 16. The reactive power amount adjustment unit adjusts the target reactive power amount derived by the target reactive power amount deriving unit so that the target reactive power amount becomes zero over a predetermined duration. The islanding operation detection device according to any one of claims 8 to 17, wherein 2 reactive power amount adjustment is performed.   The second reactive power amount adjustment unit adjusts the target reactive power amount derived by the target reactive power amount derivation unit such that the target reactive power amount becomes zero with a predetermined change amount. The islanding detection device according to any one of claims 8 to 18, wherein power amount adjustment is performed. The first reactive energy derivation unit derives a first reactive energy based on a first function having a first slope indicating a relationship between a frequency deviation and a first reactive energy.
The reactive power adjustment unit is configured to cause the first reactive power derivation unit to derive the first reactive power based on a second function having a second slope smaller than the first slope. 19. The islanding detection device according to any one of claims 8 to 18, wherein quantity adjustment is performed. It further comprises a frequency measurement unit that measures the frequency of the AC power supply every reference cycle,
The frequency deviation deriving unit is a latest moving average value which is a moving average value of each frequency from the frequency in the latest period measured by the frequency measuring unit to the first number of cycles before the latest period The difference from the past moving average value, which is the moving average value of each frequency from the past period before the first time to the second period, is derived as a frequency deviation,
The reactive power amount adjustment unit causes the frequency deviation derivation unit to adjust the frequency deviation so that the frequency deviation derived by the frequency deviation derivation unit becomes smaller, and the first reactive power amount is adjusted based on the adjusted frequency deviation. The islanding operation detection device according to any one of claims 8 to 18, wherein the second reactive energy adjustment is performed by causing a deriving unit to derive the first reactive energy. It further comprises a frequency measurement unit that measures the frequency of the AC power supply every reference cycle,
The frequency deviation deriving unit is a latest moving average value which is a moving average value of each frequency from the frequency in the latest period measured by the frequency measuring unit to the first number of cycles before the latest period The difference from the past moving average value, which is the moving average value of each frequency from the past period before the first period determined from the second period to the second period, is derived as a frequency deviation,
The reactive power amount adjustment unit is a moving average value of each frequency from the latest period to the third period more than the second number from the latest period before the first period as the moving average value of the past. And the frequency deviation deriving unit derives a frequency deviation from the difference between the latest moving average value and the first reactive energy derivation unit based on the derived frequency deviation. The islanding operation detection device according to any one of claims 8 to 18, wherein the second reactive power adjustment is performed. It further comprises a frequency measurement unit that measures the frequency of the AC power supply every reference cycle,
The frequency deviation deriving unit is a latest moving average value which is a moving average value of each frequency from the frequency in the latest period measured by the frequency measuring unit to the first number of cycles before the latest period The difference from the past moving average value, which is the moving average value of each frequency from the past period before the first time determined from 1 to the second number period, is derived as a frequency deviation,
The reactive power amount adjustment unit is configured to adjust each frequency from the past period before the second time which is shorter than the first time determined from the latest period as the moving average value of the past to the period before the second number. The frequency deviation is derived by the frequency deviation deriving unit from the difference between the moving average value and the latest moving average value, and the first reactive energy amount deriving unit determines the first reactive energy based on the derived frequency deviation. The islanding operation detection device according to any one of claims 8 to 18, wherein the second reactive power adjustment is performed by causing the The reactive power amount adjustment unit executes the second reactive power amount adjustment when the frequency deviation changes in a convergence direction after the frequency deviation is out of the predetermined deviation range. The islanding detection device according to any one of claims 8 to 23. The reactive power amount adjustment unit changes temporal change of the target reactive power amount derived by the target reactive power amount derivation portion when the frequency deviation is changing in the convergence direction, the frequency deviation changes in the divergence direction By adjusting the target reactive power derived by the target reactive power deriving unit so that the target reactive power derived by the target reactive power deriving unit is more gradual than the temporal change of the target reactive power derived by the target reactive power deriving unit. The islanding operation detection device according to any one of claims 8 to 24, wherein the second reactive energy adjustment is performed. An islanding operation detecting device according to any one of claims 1 to 25,
A control unit configured to control the amount of reactive power output by the power conversion unit based on the target reactive power derived by the target reactive power deriving unit. The control device according to claim 26,
A power conditioner comprising: the power conversion unit controlled by the control device and converting direct current from a distributed power source into alternating current. A power conditioner according to claim 27;
A power supply system comprising the distributed power supply. An islanding operation detection method for detecting an islanding operation of a power conversion unit connected to an AC power supply, comprising:
A frequency deviation deriving step of deriving a frequency deviation of the AC power supply;
A first reactive power amount deriving step of deriving a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived in the frequency deviation deriving step;
A voltage change amount deriving step of deriving a voltage change amount of the voltage output from the power conversion unit;
A target reactive power amount deriving step for deriving a target reactive power amount to be output by the power conversion unit for the islanding operation detection based on the first reactive power amount derived in the first reactive power amount deriving step When,
A target reactive power adjustment step of executing a first reactive power adjustment to adjust the target reactive power derived in the target reactive power deriving step based on the magnitude of the voltage change amount;
A voltage change amount acquisition step of acquiring a voltage change amount of a voltage output from the AC power supply;
A correlation function deriving step of deriving a correlation function indicating a correlation between the frequency deviation and the voltage change amount ,
The target reactive energy adjustment step performs the first reactive energy adjustment in accordance with a value indicated by the correlation function derived by the correlation function deriving step . An islanding operation detection method for detecting an islanding operation of a power conversion unit connected to an AC power supply, comprising:
  A frequency deviation deriving step of deriving a frequency deviation of the AC power supply;
  A first reactive power amount deriving step of deriving a first reactive power amount used for islanding operation detection of the power conversion unit based on the frequency deviation derived in the frequency deviation deriving step;
  A voltage change amount deriving step of deriving a voltage change amount of the voltage output from the power conversion unit;
  A target reactive power amount deriving step for deriving a target reactive power amount to be output by the power conversion unit for the islanding operation detection based on the first reactive power amount derived in the first reactive power amount deriving step When,
  A target reactive power adjustment step of executing a first reactive power adjustment to adjust the target reactive power derived in the target reactive power deriving step based on the magnitude of the voltage change amount;
Equipped with
  In the target reactive power adjustment step, after the frequency deviation becomes out of a predetermined deviation range, temporally of the target reactive power amount derived by the target reactive power derivation step at a predetermined timing. The islanding operation detection method according to claim 1, further comprising: performing a second reactive power adjustment to adjust the target reactive power derived in the target reactive power deriving step so that the change becomes gentle.

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