JP6129562B2 - Disconnection detection device and disconnection detection method - Google Patents

Description

  The present invention relates to a disconnection detection device and a disconnection detection method for detecting disconnection of a distribution line.

  A disconnection detection device for detecting disconnection of a distribution line in a distribution network has been developed. For example, there is a method of detecting disconnection by detecting the voltage of each phase of the distribution line (see Patent Document 1). However, in this case, only the disconnection upstream of the voltage detection point (power supply side) can be detected. It is difficult to detect a disconnection on the downstream side (load side).

  As a method of detecting a failure on the downstream side (load side), a distance relay that detects a failure in a transmission line is known (for example, see Patent Document 2). The distance relay detects the voltage and current of the transmission line, calculates the impedance value corresponding to the distance to the failure point of the transmission line, and if the impedance value is within the preset impedance range, It is determined that an accident occurred within the monitoring section.

JP 2007-282451 A JP 2012-23923 A

  The distance relay estimates the distance from the calculated impedance value to the failure point using the nominal impedance value per transmission line distance, and operates when the failure point is within the monitoring section. Since the influence of the change in the impedance value in the transmission line due to the load fluctuation is small, the malfunction does not occur due to the load fluctuation. However, since the influence of the change in the impedance value due to the load fluctuation in the distribution line is great, there may be a case where a malfunction occurs when a distance relay is used for the distribution line. That is, the change in the impedance value due to the load variation may be determined as the change in the impedance value due to the disconnection of the distribution line, and the operation may be performed.

  The present invention has been conceived under the circumstances described above, and an object of the present invention is to provide a distribution line disconnection detection device capable of detecting a disconnection on the downstream side of the position where the circuit is disposed. .

  In order to solve the above problems, the present invention takes the following technical means.

The disconnection detection device provided by the first aspect of the present invention is a disconnection detection device for detecting disconnection of a distribution line, based on an electrical signal detected by an electrical signal detector disposed on the distribution line, Based on the impedance detection means for detecting the impedance value downstream of the position where the electrical signal detector of the distribution line is arranged, and the impedance value detected by the impedance detection means, whether or not the distribution line is disconnected Disconnection determination means for determining whether the impedance detection means detects impedance values of three-phase distribution lines, and the disconnection determination means includes three impedance values detected by the impedance detection means. Determining means for determining whether or not each has changed, and the determining means determined that all have changed The case, characterized in that one of the distribution line is provided with determining means for determining a disconnected.

  In a preferred embodiment of the present invention, the determination means determines whether or not reactance components of the three impedance values have changed.

  In a preferred embodiment of the present invention, the determination means determines that the reactance component has changed when a change amount of the reactance component in a predetermined time is equal to or greater than a predetermined value.

  In a preferred embodiment of the present invention, the system further comprises reactive power detection means for detecting reactive power of the distribution lines of each phase, and the disconnection judgment means has three reactive powers detected by the reactive power detection means. Second determining means for determining whether or not each has changed, wherein the determining means determines that all have been changed by the determining means, and has determined that all have changed by the second determining means. If it is determined that any of the distribution lines is disconnected.

  In a preferred embodiment of the present invention, there is further provided a disconnection phase detection means for detecting a phase in which the most changed resistance component among the resistance components of the three impedance values is detected as a phase in which the distribution line is disconnected. .

  In a preferred embodiment of the present invention, the active power detecting means for detecting the active power of each phase distribution line, and the most varied active power among the three active powers detected by the active power detecting means is detected. And a broken phase detecting means for detecting the phase thus detected as a phase in which the distribution line is broken.

The disconnection detection device provided by the second aspect of the present invention is a disconnection detection device for detecting disconnection of a distribution line, based on an electrical signal detected by an electrical signal detector disposed on the distribution line, Based on the impedance detection means for detecting the impedance value downstream of the position where the electrical signal detector of the distribution line is arranged, and the impedance value detected by the impedance detection means, whether or not the distribution line is disconnected A disconnection determination means for determining whether or not the disconnection determination means includes a differential value calculation means for calculating a differential value of a reactance component of the impedance value detected by the impedance detection means, and the calculated differential value. Judgment means for judging that the distribution line is disconnected when the state in which the value is a positive value becomes a negative value after continuing for a predetermined time or more. Characterized in that it comprises a.

  In a preferred embodiment of the present invention, a frequency detection means for detecting a system frequency of the distribution line, and a filter means for extracting a component of the system frequency from a current signal and a voltage signal detected by the electrical signal detector, respectively. And further.

The disconnection detection method provided by the third aspect of the present invention is a disconnection detection method for detecting disconnection of a distribution line, wherein the electrical signal detector disposed on the distribution line detects an electrical signal. A second step of detecting an impedance value downstream of the position where the electric signal detector of the distribution line is arranged based on the electric signal detected in the first step, and the second step And a third step of determining whether or not the distribution line is disconnected based on the impedance value detected in the step , wherein the impedance value of the three-phase distribution line is provided in the second step. In the third step, in the third step, it is determined whether or not the three impedance values detected in the second step have changed, respectively, and the 3-1 By process All Te is when it is determined to have changed, characterized in that one of the distribution lines and a 3-2 step of determining that disconnection. Furthermore, the disconnection detection method provided by the fourth aspect of the present invention is a disconnection detection method for detecting disconnection of a distribution line, wherein an electrical signal detector disposed on the distribution line detects an electrical signal. And a second step of detecting an impedance value downstream of the position where the electric signal detector of the distribution line is arranged based on the electric signal detected in the first step, And a third step of determining whether or not the distribution line is disconnected based on the impedance value detected in the second step. In the third step, the second step includes The step 3-1 for calculating the differential value of the reactance component of the detected impedance value, and the case where the calculated differential value is a positive value after a negative value has continued for a predetermined time or longer. , Said arrangement Characterized in that it comprises a 3-2 step of determining that the line is disconnected.

  According to the present invention, the impedance detection means detects the impedance value downstream from the arrangement position of the electrical signal detector of the distribution line, and whether the distribution line is disconnected based on the detected impedance value. Judging. When the distribution line is disconnected downstream from the position where the electrical signal detector is disposed, the detected impedance value changes in a specific manner. Therefore, the disconnection determination means detects the disconnection by detecting this specific change. . Therefore, the disconnection detection device according to the present invention can detect a disconnection on the downstream side of the position where the disconnection is detected.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a figure for demonstrating the disconnection detection apparatus which concerns on 1st Embodiment. It is a functional block diagram for demonstrating the structure of an a phase calculating part. It is a wave form diagram which shows the time series change of the reactance component calculated by the calculating part in simulation. It is a wave form diagram which shows the time-sequential change of the resistance component calculated by the calculating part in simulation. It is a flowchart for demonstrating the disconnection judgment process which a judgment part performs. It is a wave form diagram which shows the time-sequential change of the reactive power value calculated by the calculating part in simulation. It is a wave form diagram which shows the time series change of the active electric power value calculated in the calculating part in simulation. It is a figure for demonstrating the disconnection detection apparatus which concerns on 2nd Embodiment. It is a figure for demonstrating the disconnection detection apparatus which concerns on 3rd Embodiment. It is a figure for demonstrating the disconnection detection apparatus which concerns on 4th Embodiment.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a diagram for explaining the disconnection detection device according to the first embodiment, and shows a state in which it is arranged in a three-phase distribution line model.

  The disconnection detection device A1 detects a disconnection on the downstream side of the distribution line. This embodiment demonstrates the case where the disconnection detection apparatus A1 detects the disconnection of the three-phase distribution line which consists of the a-phase distribution line a, the b-phase distribution line b, and the c-phase distribution line c.

A customer R11 and a customer R21 are connected between the distribution line a and the distribution line b, a customer R12 and a customer R22 are connected between the distribution line b and the distribution line c, and the distribution line c and A consumer R13 and a consumer R23 are connected to the distribution line a. An instrumental current transformer CT1 is disposed on the distribution line a, an instrumental current transformer CT2 is disposed on the distribution line b, and an instrumental current transformer CT3 is disposed on the distribution line c. . The instrument current transformers CT1, CT2, and CT3 detect currents flowing through the respective distribution lines. The current signals i _a , i _{b, and ic} detected by the instrument current transformers CT1, CT2, and CT3 are input to the disconnection detection device A1. Note that other current detection devices (for example, photocurrent measurement) may be used in place of the current transformers CT1, CT2, and CT3. An instrument transformer PT1 is arranged between the distribution line a and the distribution line b, and an instrument transformer PT2 is arranged between the distribution line b and the distribution line c. An instrument transformer PT3 is disposed between c and the distribution line a. The instrument transformers PT1, PT2, PT3 each detect a line voltage between distribution lines. The voltage signals v _ab , v _{bc, and} v _ca detected by the instrument transformers PT1, PT2, and PT3 are input to the disconnection detector A1. Instead of the instrument transformers PT1, PT2, PT3, other voltage detection devices (for example, capacitor partial pressure) may be used. Circuit breakers CB1, CB2, CB3 are provided downstream of the instrument current transformers CT1, CT2, CT3 and the instrument transformers PT1, PT2, PT3. The circuit breakers CB1, CB2, and CB3 block the currents flowing through the distribution lines a, b, and c, respectively, in response to the disconnection command input from the disconnection detection device A1.

  In FIG. 1, the disconnection of the distribution line a between the customer R11 and the customer R21 is schematically represented as the switch SW1 being opened. Further, the load fluctuation of the customer R21 connected between the distribution line a and the distribution line b is changed from the state where the customer R21 is using power (the switch SW2 is closed) to the state where the power is not used (switch It is schematically shown that SW2 changes to open.

Breaking detection device A1 is the current transformer CT1, CT2, the current signal is input from each _{CT3 i a, i b, i} c, and a voltage signal are input from the potential transformer PT1, PT2, PT3 A disconnection is detected based on v _ab , v _{bc, and} v _ca, and a disconnection command for opening the circuit breakers CB1, CB2, and CB3 that are normally closed is output. The disconnection detection device A1 includes a calculation unit 1, a determination unit 2, a cutoff command unit 3, and a notification unit 4.

  The calculation unit 1 calculates an impedance value, an active power value, and a reactive power value based on the input voltage signal and current signal. In order to calculate these values for each phase, the calculation unit 1 calculates an a-phase calculation unit 11 that calculates each value of the a-phase distribution line a, and a b-phase calculation that calculates each value of the b-phase distribution line b. And a c-phase calculation unit 13 for calculating each value of the c-phase distribution line c.

  FIG. 2 is a functional block diagram for explaining the configuration of the a-phase calculation unit 11. Note that the configurations of the b-phase calculation unit 12 and the c-phase calculation unit 13 are the same as the configuration of the a-phase calculation unit 11, and thus the description thereof is omitted.

a phase calculation unit 11 is input a voltage signal v _ab current signals i _a and the potential transformer PT1 current transformer CT1 detects detects, current transformer for CT1 and instrument meter distribution lines a Impedance values (resistance component Ra and reactance component Xa) downstream from the arrangement position of transformer PT1 (hereinafter referred to as “detection position”), active power value Pa and reactive power value Qa supplied by distribution line a Is output to the determination unit 2. The a-phase calculation unit 11 includes A / D conversion units 111 and 112, filter units 113 and 114, an impedance calculation unit 115, and a power calculation unit 116.

The A / D converter 111 converts the voltage signal v _ab that is an analog signal input from the instrument transformer PT1 into a digital signal. That is, the voltage signal v _ab is sampled at a predetermined timing and converted into a digital voltage signal. A / D converter 112 converts the current signal i _a is an analog signal input from the current transformer CT1 to a digital signal. That is, the current signal ia is sampled at _a predetermined timing and converted into a digital current signal.

  The filter unit 113 is a low-pass filter, removes harmonic components from the digital voltage signal input from the A / D conversion unit 111, and outputs the harmonic component to the impedance calculation unit 115 and the power calculation unit 116. The filter unit 114 is a low-pass filter, removes harmonic components from the digital current signal input from the A / D conversion unit 112, and outputs the harmonic component to the impedance calculation unit 115 and the power calculation unit 116. In this embodiment, the filter units 113 and 114 are used as digital filters to perform filtering on the digital signal after A / D conversion, but the present invention is not limited to this. Instead of or in addition to the filter units 113 and 114, an analog filter may be provided before the A / D conversion units 111 and 112.

The impedance calculation unit 115 calculates an impedance value (resistance component Ra and reactance component Xa) from the digital voltage signal input from the filter unit 113 and the digital current signal input from the filter unit 114, and determines the determination unit 2. Output to. In this embodiment, from the digital voltage signal and the digital current signal, the effective voltage value V _{ab of} the a-phase and b-phase line voltages, the effective current value I _a of the a-phase phase current, and the line voltage and phase The current phase difference φ is calculated, and the resistance component Ra and the reactance component Xa are calculated from these calculation results. The method of calculating the impedance value is not limited to this, and the impedance value may be calculated using a differential equation or an integral equation.

The power calculation unit 116 calculates the active power value Pa and the reactive power value Qa from the digital voltage signal input from the filter unit 113 and the digital current signal input from the filter unit 114, and outputs the result to the determination unit 2. To do. In this embodiment, similar to the impedance calculation unit 115, the voltage effective value V _ab , the current effective value I _a , and the phase difference φ are calculated, and the active power value Pa and the reactive power value Qa are calculated from these calculation results. doing. Note that the calculation may be performed using the effective voltage value V _ab , the effective current value I _a , and the phase difference φ calculated by the impedance calculation unit 115, or from the digital voltage signal and the digital current signal that are instantaneous values. You may make it calculate.

  Returning to FIG. 1, the determination unit 2 determines the occurrence of disconnection and identifies the disconnected distribution line, and is realized by, for example, a microcomputer. The determination unit 2 includes a resistance component Ra, a reactance component Xa, an active power value Pa, and a reactive power value Qa input from the a-phase calculation unit 11, and a resistance component Rb and a reactance component Xb input from the b-phase calculation unit 12. The determination is made based on the active power value Pb and the reactive power value Qb, and the resistance component Rc, reactance component Xc, active power value Pc, and reactive power value Qc input from the c-phase calculation unit 13. The determination unit 2 determines the occurrence of a disconnection by capturing a characteristic change in impedance when the disconnection occurs. When the determination unit 2 determines that a disconnection has occurred, the determination unit 2 outputs information on the occurrence of the disconnection and the distribution line in which the disconnection has occurred to the cutoff command unit 3 and the notification unit 4.

  It has been found through experiments by the inventors that when a disconnection occurs in the three-phase distribution lines a, b, and c, the reactance components Xa, Xb, and Xc of the three-phase impedance all change greatly. On the other hand, when the load of any of the customers R11 to R23 connected between the distribution lines a, b, and c greatly fluctuates, it corresponds to the two-phase distribution line connected by the customer whose load has fluctuated It is known that the reactance component to be changed greatly, but the reactance component corresponding to the other phase distribution line does not change so much.

  In the three-phase distribution line model shown in FIG. 1, the demand connected between the distribution line a and the distribution line b by opening the switch SW1 and simulating the disconnection of the distribution line a, and opening the switch SW2. A simulation was performed by simulating the load fluctuation of the house R21. The waveform shown in FIG. 3 shows the time series change of the reactance components Xa, Xb, and Xc calculated by the calculation unit 1 in the simulation. FIG. 4A shows a waveform when a disconnection occurs, and FIG. 4B shows a waveform when the load fluctuates. Each reactance component Xa, Xb, Xc is stable at 30Ω and the switch SW1 or SW2 is opened at 0.05 s.

  As shown in FIG. 5A, when the switch SW1 is opened (that is, disconnection occurs in the distribution line a), all of the reactance components Xa, Xb, and Xc change greatly. On the other hand, as shown in FIG. 5B, when the switch SW2 is opened (that is, the load fluctuation of the customer R21 connected between the distribution line a and the distribution line b occurs), the reactance component Xa. , Xb change greatly, but the reactance component Xc does not change much.

  Therefore, by looking at changes in the reactance components Xa, Xb, and Xc, it is possible to exclude changes due to load fluctuations and capture characteristic changes in impedance when disconnection occurs. Note that the disconnection determination in this embodiment is performed every 10 milliseconds, and it is almost impossible for two or more customers to simultaneously change the load in this short time. Assumes load fluctuations.

  The determination unit 2 determines that a disconnection has occurred only when all of the reactance components Xa, Xb, and Xc have changed. In the present embodiment, differences from reactance components Xa, Xb, and Xc acquired at the previous disconnection determination timing are calculated, and it is determined that the difference has changed when the absolute value of the difference is equal to or greater than a predetermined threshold. For example, a disconnection determination is performed every 10 milliseconds, and when the reactance components Xa, Xb, and Xc increase or decrease by 2Ω or more from the previous time, it is determined that the reactance component has changed.

  In FIG. 3A, since the reactance components Xa, Xb, and Xc all increase or decrease by 2Ω or more at the timing of 0.06 s, it is determined that a disconnection has occurred. On the other hand, in FIG. 3B, the reactance component Xa increases by 2Ω or more at the timing of 0.06 s, but the increase / decrease of the reactance components Xb and Xc is less than 2Ω, and the reactance component Xa at the timing of 0.07 s. , Xb increases or decreases by 2Ω or more, but since the increase or decrease of the reactance component Xc is less than 2Ω, it is not determined that a disconnection has occurred.

  In this embodiment, the disconnection determination is performed every 10 milliseconds, but the disconnection determination timing is not limited to this. Also, the increase / decrease threshold for determining whether or not the change has occurred is not limited to 2Ω. If more delicate changes are to be detected, the disconnection judgment timing interval may be shortened to a smaller value, and if larger changes are to be detected, the disconnection judgment timing interval may be reduced. The threshold may be increased to a larger value. Alternatively, it may be determined that a disconnection has occurred only when the determination that all of the reactance components Xa, Xb, and Xc have changed is continued a plurality of times, or the reactance components Xa, Xb, and Xc all change. It may be determined that the disconnection has occurred only when the determination that it has been performed continues for a predetermined time. The method for determining whether or not the change has occurred is not limited to the above. You may make it discriminate | determine that each reactance component Xa, Xb, Xc changed when it exceeded the set range, respectively. Further, it may be determined that the differential value of each reactance component Xa, Xb, Xc has changed when it exceeds a set range.

  It has also been found by experiments by the inventors that the resistance component corresponding to the distribution line in which the disconnection occurs changes from the resistance component corresponding to the other distribution lines.

  The waveforms shown in FIG. 4 indicate time-series changes of the resistance components Ra, Rb, and Rc calculated by the calculation unit 1 in the simulation described with reference to FIG. FIG. 4A shows a waveform when a disconnection occurs, and FIG. 4B shows a waveform when the load fluctuates. Each of the resistance components Ra, Rb, Rc is stable at 50Ω and the switch SW1 or SW2 is opened at 0.05 s.

  As shown in FIG. 5A, when the switch SW1 is opened (that is, a break occurs in the distribution line a), the resistance component Ra corresponding to the distribution line a becomes the resistance component Rb corresponding to the distribution line b. The resistance component Rc corresponding to the distribution line c is greatly changed.

  Therefore, the distribution line in which the disconnection has occurred can be identified by looking at changes in the resistance components Ra, Rb, and Rc. When determining that the disconnection has occurred, the determination unit 2 determines that the distribution line of the phase having the largest change among the resistance components Ra, Rb, and Rc is disconnected. In the present embodiment, differences from the resistance components Ra, Rb, and Rc acquired at the timing of the previous disconnection determination are calculated, respectively, and it is determined that the change is largest when the absolute value of the difference is the largest.

  In FIG. 4A, the absolute value of the difference between the timing of the resistance component Ra at the timing of 0.06 s (when the disconnection is determined to occur) and the timing of 0.05 S is the resistance components Rb and Rc. Therefore, it is determined that the change in the resistance component Ra is the largest, and it is determined that the a-phase distribution line a corresponding to the resistance component Ra is disconnected.

  FIG. 5 is a flowchart for explaining disconnection determination processing performed by the determination unit 2. The disconnection determination process is started when the disconnection detection device A1 is activated.

  First, the calculated value calculated by the calculation unit 1 is acquired (S1). In the present embodiment, the disconnection determination is performed every 10 milliseconds, so that the calculation value is acquired every 10 milliseconds.

  Next, it is determined whether or not the reactance component Xa has changed (S2). When it is determined that the reactance component Xa has changed (S2: YES), it is determined whether or not the reactance component Xb has changed (S3). When it is determined that the reactance component Xb has changed (S3: YES), it is determined whether or not the reactance component Xc has changed (S4). When it is determined that the reactance component Xc has changed (S4: YES), the process proceeds to step S5. If it is determined in steps S2, S3, and S4 that there is no change (S2: NO, S3: NO, or S4: NO), it is determined that no disconnection has occurred, and the process returns to step S1. That is, only when it is determined that all of the reactance components Xa, Xb, and Xc have changed, it is determined that the disconnection has occurred, and the process proceeds to the step of identifying the distribution line in which the disconnection has occurred in steps S5 to S9.

  Next, it is determined whether or not the change in the resistance component Ra is larger than the changes in the resistance components Rb and Rc (S5). If the change in the resistance component Ra is the maximum (S5: YES), it is determined that a disconnection has occurred in the a-phase distribution line a, information indicating that is output (S6), and the disconnection determination process ends. When the change in the resistance component Ra is not the maximum (S5: NO), it is determined whether or not the change in the resistance component Rb is larger than the changes in the resistance components Ra and Rc (S7). When the change in the resistance component Rb is the maximum (S7: YES), it is determined that a disconnection has occurred in the b-phase distribution line b, information indicating that is output (S8), and the disconnection determination process ends. If the change in the resistance component Rb is not the maximum (S7: NO), the change in the resistance component Rc is the maximum, so it is determined that the disconnection has occurred in the c-phase distribution line c, and information to that effect is output ( S9), the disconnection determination process ends. That is, the information which shows that the disconnection generate | occur | produced with the distribution line corresponding to the resistance component with the largest change is output, and a disconnection judgment process is complete | finished. Note that the flowchart of the disconnection determination process is not limited to that shown in FIG.

  Further, it has been found by the inventors' experiments that when the three-phase distribution lines a, b, and c are disconnected, the three-phase reactive power values Qa, Qb, and Qc greatly change. On the other hand, when the load of any of the customers R11 to R23 connected between the distribution lines a, b, and c greatly fluctuates, it corresponds to the two-phase distribution line connected by the customer whose load has fluctuated It is known that the reactive power value to be greatly changed, but the reactive power value corresponding to the other phase distribution line does not change so much.

  The waveforms shown in FIG. 6 indicate time-series changes in the reactive power values Qa, Qb, and Qc calculated by the calculation unit 1 in the simulation described with reference to FIG. FIG. 4A shows a waveform when a disconnection occurs, and FIG. 4B shows a waveform when the load fluctuates. Each reactive power value Qa, Qb, Qc is stable at 650 var and the switch SW1 or SW2 is opened at 0.05 s.

  As shown in FIG. 5A, when the switch SW1 is opened (that is, a disconnection occurs in the distribution line a), the reactive power values Qa, Qb, and Qc all change greatly. On the other hand, as shown in FIG. 5B, when the switch SW2 is opened (that is, the load fluctuation of the customer R21 connected between the distribution line a and the distribution line b occurs), the reactive power value is obtained. Although Qa and Qb have changed greatly, the reactive power value Qc has not changed much.

  Therefore, in addition to the determination of disconnection due to changes in reactance components Xa, Xb, and Xc, determination of disconnection due to changes in reactive power values Qa, Qb, and Qc may be further performed. Specifically, a step of determining whether or not all of the reactive power values Qa, Qb, and Qc have changed before proceeding to step S5 in the case of “YES” in step S4 of the flowchart shown in FIG. 5 is added. It will be. If all of the reactive power values Qa, Qb, and Qc have changed, the process proceeds to step S5, and if any one of them has not changed, the process may return to step S1.

  The determination as to whether or not each reactive power value Qa, Qb, Qc has changed may be performed by a method similar to the determination in the case of the reactance components Xa, Xb, Xc, or may be determined by another method. Also good. For example, a disconnection determination may be performed every 10 milliseconds, and it may be determined that the reactance component has changed when the reactive power values Qa, Qb, and Qc have increased or decreased by 100 var or more from the previous time.

  In FIG. 6A, the reactive power values Qa, Qb, and Qc are all 100 var at the timing of 0.05 s (when it is determined that disconnection has occurred due to changes in the reactance components Xa, Xb, and Xc). Since it has increased or decreased as described above, it is determined that a disconnection has occurred.

  In FIG. 6B, the reactive power value Qb decreases by 100 var or more at the timing of 0.06 s and the timing of 0.07 S, but the increase and decrease of the reactive power values Qa and Qc are less than 100 var, respectively. Therefore, it is not determined that a disconnection has occurred. Therefore, it may be possible to determine only the disconnection due to the change in the reactive power values Qa, Qb, and Qc without determining the disconnection due to the change in the reactance components Xa, Xb, and Xc.

  It has also been found by experiments by the inventors that the effective power value corresponding to the distribution line in which the disconnection has occurred changes from the effective power value corresponding to the other distribution lines.

  The waveforms shown in FIG. 7 indicate time-series changes in the active power values Pa, Pb, and Pc calculated by the calculation unit 1 in the simulation described with reference to FIG. FIG. 4A shows a waveform when a disconnection occurs, and FIG. 4B shows a waveform when the load fluctuates. Each of the active power values Pa, Pb, and Pc is stable at 1000 W, and the switch SW1 or SW2 is opened at 0.05 s.

  As shown in FIG. 5A, when the switch SW1 is opened (that is, a break occurs in the distribution line a), the active power value Pa corresponding to the distribution line a becomes the active power corresponding to the distribution line b. It is greatly changed from the active power value Pc corresponding to the value Pb and the distribution line c.

  Therefore, instead of specifying the broken distribution line by changing the resistance components Ra, Rb, Rc, the broken distribution line may be specified by changing the active power values Pa, Pb, Pc. Specifically, it is determined whether or not the change in the active power value Pa is the maximum in step S5 of the flowchart shown in FIG. 5, and whether or not the change in the active power value Pb is the maximum in step S7. What is necessary is just to change so that it may discriminate.

  The determination of which change in each of the active power values Pa, Pb, and Pc is the maximum may be performed by the same method as the determination in the case of the resistance components Ra, Rb, and Rc, or may be determined by another method. You may do it. For example, the difference from the active power values Pa, Pb, and Pc acquired at the previous disconnection determination timing may be calculated, respectively, and it may be determined that the change is largest when the absolute value of the difference is the largest.

  In FIG. 7A, the absolute value of the difference between the active power value Pa at the timing of 0.06 s (when it is determined that a disconnection has occurred) and the 0.05 S timing is the active power value Pb. , Pc, it is determined that the change in the active power value Pa is the largest, and it is determined that the a-phase distribution line a corresponding to the active power value Pa is disconnected.

  Note that the method for determining the occurrence of disconnection in the determination unit 2 and the method for identifying the distribution line in which the disconnection has occurred are not limited to those described above. The determination unit 2 only needs to be able to determine the occurrence of a disconnection by capturing a characteristic change in impedance when the disconnection occurs.

  Returning to FIG. 1, the shut-off command unit 3 outputs a shut-off command to the circuit breakers CB 1, CB 2, and CB 3 based on information input from the determination unit 2. When the information indicating that the disconnection has occurred in the distribution line a is input, the interruption command unit 3 outputs the interruption command to the circuit breaker CB1 and opens the circuit breaker CB1. Similarly, when information indicating that a break has occurred in the distribution line b is input, a break command is output to the circuit breaker CB2, the breaker CB2 is opened, and information indicating that a break has occurred in the distribution line c Is input, a break command is output to the breaker CB3 to open the breaker CB3.

  Based on the information input from the determination unit 2, the notification unit 4 notifies that the disconnection has occurred and information on the distribution line in which the disconnection has occurred. In this embodiment, the alerting | reporting part 4 is a monitor and a buzzer, warns with a buzzer that a disconnection generate | occur | produced, and displays the distribution line which a disconnection generate | occur | produced on the monitor screen. In addition, you may make it notify the distribution line with which the disconnection generate | occur | produced with the audio | voice.

  In addition, the process which each part of the disconnection detection apparatus A1 performs may be designed by a program, and the computer may function as the disconnection detection apparatus A1 by executing the program. The program may be recorded on a recording medium and read by a computer.

  In the present embodiment, the impedance calculation unit 115 of the a-phase calculation unit 11 calculates the impedance values (resistance component Ra and reactance component Xa) on the downstream side from the detection position of the distribution line a. Further, an impedance calculation unit (not shown) of the b-phase calculation unit 12 calculates an impedance value (resistance component Rb and reactance component Xb) downstream from the detection position of the distribution line b, and an impedance calculation unit (not shown) of the c-phase calculation unit 13 Calculates an impedance value (resistance component Rc and reactance component Xc) downstream of the detection position of the distribution line c. The determination unit 2 determines that a disconnection has occurred downstream from the detection position when all of the calculated reactance components Xa, Xb, and Xc have changed significantly. Therefore, the disconnection detection device A1 can detect a disconnection downstream of the detection position.

  The reactance components Xa, Xb, and Xc all change greatly when a disconnection occurs, but any two of them change greatly in the case of a load change, and one of them does not change so much. Therefore, the disconnection detection device A1 can detect the disconnection in distinction from the load variation, and can suppress erroneous detection due to the load variation.

  When determining that the disconnection has occurred, the determination unit 2 determines that the distribution line of the phase having the largest change among the resistance components Ra, Rb, and Rc is disconnected. Since there is a characteristic that the resistance component corresponding to the distribution line in which the disconnection occurs is the largest, the disconnection detection apparatus A1 can appropriately identify the distribution line in which the disconnection has occurred.

  In the present embodiment, the determination unit 2 receives the resistance components Ra, Rb, Rc, the reactance components Xa, Xb, Xc, the active power values Pa, Pb, Pc, and the reactive power values Qa, Qb, Qc from the calculation unit 1. Although the case where all are input was demonstrated, it is not restricted to this. What is not necessary for the determination by the determination unit 2 may not be input, and may not be calculated by the calculation unit 1. For example, when the broken distribution line is specified by changing the resistance components Ra, Rb, and Rc, the active power values Pa, Pb, and Pc need not be calculated.

  Moreover, although this embodiment demonstrated the case where the determination part 2 performed to the identification of the disconnected distribution line in addition to disconnection determination, it is not restricted to this. For example, when disconnection occurs, when all the circuit breakers CB1, CB2, and CB3 are opened to interrupt all the currents of the distribution lines a, b, and c, it is not necessary to specify the disconnected distribution line. . Therefore, the determination unit 2 may perform only disconnection determination. In this case, the determination unit 2 outputs information indicating that a disconnection has occurred to the breaker command unit 3 and the notification unit 4, and the breaker command unit 3 outputs a breakage command to the breakers CB1, CB2, and CB3 to output the breaker CB1. , CB2 and CB3 are opened, and the notification unit 4 notifies that a disconnection has occurred.

  In this embodiment, the case where the instrument transformers PT1, PT2, and PT3 each detect the line voltage between the distribution lines has been described. However, the instrument transformers PT1, PT2, and PT3 each detect the phase voltage of the distribution line. You may make it do.

  In an actual distribution line, since the system frequency (frequency of the power system) changes, the accuracy of each value calculated by the calculation unit 1 may deteriorate. A case where the accuracy of each value calculated by the calculation unit 1 is improved will be described below as a second embodiment.

  FIG. 8 is a diagram for explaining the disconnection detection apparatus according to the second embodiment. In the figure, the same or similar elements as those in the disconnection detection device A1 (see FIGS. 1 and 2) according to the first embodiment are denoted by the same reference numerals.

  The disconnection detection device A2 shown in FIG. 8 includes a frequency detection unit 5 and filter units 113 ′ and 114 ′ that are band-pass filters instead of the filter units 113 and 114 that are low-pass filters. This is different from the disconnection detection device A1 according to the first embodiment.

The frequency detection unit 5 detects a system frequency. The frequency detector 5 detects the system frequency based on the voltage signal v _ab input from the instrument transformer PT1. The frequency detection method is not limited, and may be a PLL method or a zero-cross point counting method. The frequency detection unit 5 outputs the detected system frequency to the filter units 113 ′ and 114 ′.

  The filter units 113 ′ and 114 ′ are band pass filters that can change the passband. The filter units 113 ′ and 114 ′ set the system frequency input from the frequency detection unit 5 as the center frequency of the pass band. The filter unit 113 ′ removes frequency components other than the system frequency component from the digital voltage signal input from the A / D conversion unit 111, and outputs the result to the impedance calculation unit 115 and the power calculation unit 116. The filter unit 114 ′ removes frequency components other than the system frequency component from the digital current signal input from the A / D conversion unit 112, and outputs the result to the impedance calculation unit 115 and the power calculation unit 116.

  In the second embodiment, the same effect as that of the first embodiment can be obtained. Moreover, since the impedance calculation unit 115 and the power calculation unit 116 calculate each value based on each digital signal from which frequency components other than the system frequency component are removed, the accuracy of each value calculated by the calculation unit 1 is improved.

  Note that the filter units 113 ′ and 114 ′ may be adaptive digital filters so that the center frequency of the passband follows the fundamental frequency of each input digital signal.

  In the first and second embodiments, the case has been described in which the disconnection is detected by detecting the characteristic change in the three-phase impedance value when the disconnection occurs, but the present invention is not limited to this. You may make it detect the disconnection of the said phase by catching the characteristic change of the impedance value for every phase. The case where a disconnection is detected for each phase will be described below as a third embodiment.

  FIG. 9 is a diagram for explaining a disconnection detection apparatus according to the third embodiment. In the figure, the same or similar elements as those in the disconnection detection device A1 (see FIG. 1) according to the first embodiment are denoted by the same reference numerals.

  The disconnection detection device A3 shown in FIG. 9 is different from the disconnection detection device A1 according to the first embodiment in that the determination unit 2 'determines the occurrence of disconnection for each phase.

  The determination unit 2 ′ includes an a-phase determination unit 21 that determines occurrence of disconnection of the a-phase distribution line a, a b-phase determination unit 22 that determines occurrence of disconnection of the b-phase distribution line b, and c-phase distribution. A c-phase determination unit 23 that determines occurrence of disconnection of the electric wire c is provided. The a-phase determination unit 21 makes a determination based on the resistance component Ra, the reactance component Xa, the active power value Pa, and the reactive power value Qa input from the a-phase calculation unit 11. The a-phase determination unit 21 determines the occurrence of a disconnection by capturing a characteristic change in impedance when the disconnection occurs. When the a-phase determination unit 21 determines that a disconnection has occurred, the a-phase determination unit 21 outputs information indicating that a disconnection has occurred in the distribution line a to the cutoff command unit 3 and the notification unit 4. Note that the configurations of the b-phase determination unit 22 and the c-phase determination unit 23 are the same as the configuration of the a-phase determination unit 21, and thus the description thereof is omitted.

  As shown in the waveform of the reactance component Xa in FIG. 3A, overshoot occurs in the waveform of the reactance component corresponding to the distribution line in which the disconnection has occurred, but no overshoot occurs in the other waveforms. Further, as shown by each waveform in FIG. 3B, overshoot does not occur in the case of load fluctuation. Therefore, when an overshoot occurs in the waveform of each reactance component Xa, Xb, Xc, it can be determined that a disconnection has occurred in the distribution line corresponding to the reactance component. When the overshoot occurs in the waveform of the reactance component Xa, the a-phase determination unit 21 determines that a disconnection has occurred in the distribution line a. In this embodiment, when the state in which the differential value of the reactance component Xa is a positive value continues to be a negative value after continuing for a predetermined time or longer (or the state in which the differential value is a negative value continues for a predetermined time or longer) If it becomes a positive value later), it is determined that an overshoot has occurred. In FIG. 3A, the reactance component Xa increases from the timing of 0.05 s (ie, the differential value is a positive value), and starts to decrease around 0.057 s (ie, the differential value). Therefore, it is determined that an overshoot has occurred, and it is determined that a break has occurred in the distribution line a. Note that it may be determined that a disconnection has occurred when the overshoot occurs twice.

  Note that the method for determining occurrence of disconnection in the determination unit 2 ′ is not limited to the above. The determination unit 2 ′ only needs to be able to determine the occurrence of disconnection by capturing the characteristic change in impedance when disconnection occurs. For example, the waveform of the time series change of the reactance component at the time of the disconnection occurrence (see FIG. 3A) is recorded in advance, and the waveform of the time series change of the reactance component is recorded with the recorded waveform at the occurrence of the disconnection and pattern matching. For example, it may be determined that a disconnection has occurred if the waveforms are similar.

  In the third embodiment, the same effect as that of the first embodiment can be obtained.

  In the said 1st-3rd embodiment, although the case where the disconnection in the three-phase distribution line a, b, c was detected was demonstrated, it is not restricted to this. The present invention can also be used when detecting disconnection in a single-phase distribution line. The case where a disconnection in a single-phase distribution line is detected will be described below as a fourth embodiment.

  FIG. 10 is a diagram for explaining the disconnection detection apparatus according to the fourth embodiment. In the figure, the same or similar elements as those in the disconnection detection device A1 (see FIG. 1) according to the first embodiment are denoted by the same reference numerals.

  The disconnection detection device A4 shown in FIG. 10 relates to the first embodiment in that it is arranged on a single-phase distribution line d and the arithmetic unit 1 ′ and the determination unit 2 ″ correspond to a single phase. Different from the disconnection detection device A1.

  The calculation unit 1 ′ has the same configuration as that of the a-phase calculation unit 11 (see FIG. 2), and receives the current signal i detected by the instrument current transformer CT and the voltage signal v detected by the instrument transformer PT. The impedance value (resistance component R and reactance component X) downstream from the detection position of the distribution line d, the active power value P and the reactive power value Q supplied by the distribution line d are calculated and output to the determination unit 2 ″ The determination unit 2 ″ has the same configuration as the a-phase determination unit 21 (see FIG. 9) according to the third embodiment, and the resistance component R, reactance component X, active power value P, and Reactive power value Q is input, occurrence of disconnection is determined based on a characteristic change in impedance when disconnection occurs, and information indicating that disconnection has occurred is output to cutoff command unit 3 and notification unit 4.

  In the fourth embodiment, the same effect as that of the first embodiment can be obtained.

  The disconnection detection device and the disconnection detection method according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the disconnection detection device and the disconnection detection method according to the present invention can be varied in design in various ways.

A1, A2, A3, A4 Disconnection detection device 1, 1 'calculation unit 11 a phase calculation unit 111, 112 A / D conversion unit 113, 114, 113', 114 'filter unit 115 impedance calculation unit (impedance detection means)
116 Power calculation unit (reactive power detection means, active power detection means)
12 b phase calculation unit 13 c phase calculation unit 2, 2 ′, 2 ″ determination unit (disconnection determination unit, determination unit, determination unit, second determination unit, disconnection phase detection unit, differential value calculation unit)
21 a-phase determination unit 22 b-phase determination unit 23 c-phase determination unit 3 shut-off command unit 4 notification unit 5 frequency detection unit a, b, c distribution line CT1, CT2, CT3 Current transformer (electric signal detector)
PT1, PT2, PT3 Instrument transformer (electric signal detector)

Claims (10)

A disconnection detection device for detecting disconnection of a distribution line,
Based on the electrical signal detected by the electrical signal detector disposed on the distribution line, impedance detection means for detecting an impedance value downstream of the position where the electrical signal detector of the distribution line is disposed;
Based on the impedance value detected by the impedance detection means, a disconnection determination means for determining whether or not the distribution line is disconnected,
Equipped with a,
The impedance detection means detects an impedance value of a three-phase distribution line,
The disconnection judgment means
Discriminating means for discriminating whether or not each of the three impedance values detected by the impedance detecting means has changed;
A determination means for determining that any of the distribution lines is disconnected when it is determined that all have changed by the determination means;
Disconnection detecting apparatus characterized in that it comprises. The determining means determines whether or not reactance components of the three impedance values have changed;
The disconnection detection apparatus according to claim 1 . The determination means determines that the reactance component has changed when a change amount of the reactance component in a predetermined time is a predetermined value or more.
The disconnection detection apparatus according to claim 2 . Reactive power detection means for detecting the reactive power of each phase distribution line, respectively, further comprises,
The disconnection determination means further includes second determination means for determining whether or not each of the three reactive powers detected by the reactive power detection means has changed,
The determination means determines that any of the distribution lines is disconnected when it is determined that all have been changed by the determination means and all have been changed by the second determination means,
The disconnection detection apparatus according to any one of claims 1 to 3 . A phase detection unit that detects a phase in which the most changed resistance component among the resistance components of the three impedance values is detected as a phase in which the distribution line is disconnected;
The disconnection detection apparatus according to any one of claims 1 to 4 . Active power detection means for detecting the active power of each phase distribution line, and
Disconnected phase detection means for detecting a phase in which the most changed active power among the three active powers detected by the active power detection means is detected as a phase in which the distribution line is disconnected,
Further equipped with,
The disconnection detection apparatus according to any one of claims 1 to 4 . A disconnection detection device for detecting disconnection of a distribution line,
Based on the electrical signal detected by the electrical signal detector disposed on the distribution line, impedance detection means for detecting an impedance value downstream of the position where the electrical signal detector of the distribution line is disposed;
Based on the impedance value detected by the impedance detection means, a disconnection determination means for determining whether or not the distribution line is disconnected,
With
The disconnection judgment means
Differential value calculating means for calculating a differential value of a reactance component of the impedance value detected by the impedance detecting means;
A determination means for determining that the distribution line is disconnected, when the calculated differential value is a negative value after the state of being a positive value continues for a predetermined time or more;
A disconnection detecting device comprising: A frequency detecting means for detecting a system frequency of the distribution line;
Filter means for extracting the component of the system frequency from the current signal and the voltage signal detected by the electrical signal detector;
Further comprising a disconnection detection device according to any one of claims 1 to 7. A disconnection detection method for detecting disconnection of a distribution line,
A first step in which an electric signal detector disposed on the distribution line detects an electric signal;
A second step of detecting an impedance value downstream of the position where the electric signal detector of the distribution line is arranged based on the electric signal detected in the first step;
A third step of determining whether the distribution line is disconnected based on the impedance value detected in the second step;
Equipped with a,
In the second step, the impedance values of the three-phase distribution lines are detected,
In the third step,
A step 3-1 for determining whether or not each of the three impedance values detected in the second step has changed;
A step 3-2 for determining that any of the distribution lines is disconnected when it is determined that all have changed by the step 3-1.
The disconnection detection method characterized by comprising. A disconnection detection method for detecting disconnection of a distribution line,
A first step in which an electric signal detector disposed on the distribution line detects an electric signal;
A second step of detecting an impedance value downstream of the position where the electric signal detector of the distribution line is arranged based on the electric signal detected in the first step;
A third step of determining whether the distribution line is disconnected based on the impedance value detected in the second step;
Equipped with a,
In the third step,
A 3-1 step of calculating a differential value of a reactance component of the impedance value detected by the second step;
A step 3-2 for determining that the distribution line is disconnected when the calculated differential value is a negative value after the state in which the differential value is a positive value continues for a predetermined time or more;
The disconnection detection method characterized by comprising.

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