JP4586770B2 - Standby uninterruptible power supply system - Google Patents

Description

  The present invention relates to a standby uninterruptible power supply system in which power is supplied from a commercial power supply to a load at all times, and power is supplied from the uninterruptible power supply to the load in the event of an abnormality such as a power failure of the commercial power supply, particularly switching from the commercial power supply to the uninterruptible power supply. The present invention relates to an output voltage control method immediately after the start of compensation.

  FIG. 12 shows the configuration of the standby uninterruptible power supply system. When the commercial power source 1 is normal, AC power is supplied from the commercial power source to the load 4 via the high-speed switch 2 and the transformer 3. The power supply voltage detection unit 5 always detects the commercial power supply voltage. When an abnormality such as a power failure, an instantaneous power failure, or an instantaneous voltage drop occurs in the commercial power source 1, the system voltage monitoring unit 6 detects this abnormality and the high-speed switch The power converter 8 controlled by the power converter control unit 7 converts the DC power of the storage element 9 into AC power after the system and the load are disconnected by the disconnection of 2 and the load 4 via the transformer 3. To supply AC power.

  In the standby uninterruptible power supply system of FIG. 12, when switching from power supply by the commercial power supply 1 to power supply by the power conversion device 8, instantaneously due to a delay in the operation of the system voltage monitoring unit 6 or a delay in the operation of the high-speed switch 2. Since the switching cannot be performed, the primary voltage of the transformer 3 fluctuates, the magnetic flux of the transformer 3 is demagnetized in one direction due to the voltage fluctuation, and an excessively demagnetizing current is generated immediately after the switching. . For this reason, the conventional standby uninterruptible power supply system has a problem that a large margin must be provided for the device capacity.

As this type of standby uninterruptible power supply system, a system that prevents and limits the bias current when switching from power supply by a commercial power supply to power supply by a power converter is proposed (for example, see Patent Document 1). This standby uninterruptible power supply calculates the power converter output voltage command by calculation so that the magnetic flux state of the internal transformer maintains positive and negative symmetry, and further the power is applied so that the magnetic flux of the transformer does not exceed the judgment value. The converter output voltage command is adjusted.
Japanese Patent No. 3570223

  In the technique described in Patent Document 1,. Although it is possible to prevent the transformer from being demagnetized, the calculation for this is complicated. This calculation detects the transformer secondary voltage, integrates this detection value, estimates the transformer magnetic flux state from the calculation result, and outputs the inverter output voltage waveform command so that this magnetic flux state is subject to positive and negative targets. Is calculated.

  Moreover, in the technique described in Patent Document 1, when switching from power feeding by a commercial power source to power feeding by a power converter, the secondary side voltage effective value (supply power) of the transformer before switching is changed. Decreases by about one cycle from the time of switching. In addition, it takes time for the reduced secondary voltage effective value in the transformer to return to the voltage effective value before switching.

  An object of the present invention is a standby uninterruptible power supply that eliminates the need for complicated calculations for preventing the magnetism of the transformer and further reduces the change in power supply (undervoltage) in switching from a commercial power supply to an uninterruptible power supply. To provide a power supply system.

  The present invention for solving the above-described problems is characterized by the following configuration.

(1) In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply.
An output voltage detector that detects a load-side voltage waveform for each half cycle;
A load-side voltage waveform storage unit for storing a load-side voltage waveform for each half cycle;
When the commercial power supply is normal, the detection waveform of the output voltage detection unit is used as an output voltage command as it is, and when a power supply abnormality occurs, the voltage waveform stored and updated in the load side voltage waveform storage unit is updated to the next of the uninterruptible power supply . And an output voltage waveform command calculation unit for generating a half cycle output voltage command value.

(2) In a standby uninterruptible power supply system that always supplies power to a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts to supply power to the load from the uninterruptible power supply.
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An effective value calculation unit for calculating an effective value of the load-side voltage waveform for each half cycle;
When the commercial power supply is normal, the output voltage detection unit uses the detected waveform as it is as the output voltage command, and when a power supply abnormality occurs, the output voltage amplitude is multiplied by the voltage effective value calculated by the effective value calculation unit as a coefficient. And an output voltage waveform command calculation unit that uses the voltage waveform as an output voltage command value for the next half cycle of the uninterruptible power supply .

(3) In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply.
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
An integration value storage unit for storing and updating the calculation result of the integration calculation unit when the commercial power supply is normal;
When an abnormality occurs in the commercial power supply, an undervoltage is calculated from the calculation result of the integral calculation unit until the uninterruptible power supply starts to supply power to the load and the integral value stored in the integral value storage unit, And an output voltage waveform command calculation unit that uses an output voltage waveform obtained by adding an undervoltage component to the output voltage waveform as an output voltage command value when power is supplied from the uninterruptible power supply to the load .

(4) In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply.
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
A reference integral value creation unit that sets the integral value of the output waveform when the commercial power supply is normal as a reference integral value;
When an abnormality occurs in the commercial power supply, the undervoltage is calculated from the calculation result of the integration calculation unit until the power supply from the uninterruptible power supply to the load and the reference integral value set in the reference integral value creation unit are calculated. And an output voltage waveform command calculation unit that uses the output voltage waveform obtained by adding the insufficient voltage to the output voltage waveform as an output voltage command value when power is supplied from the uninterruptible power supply to the load. .

(5) In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
An integration value storage unit for storing and updating the calculation result of the integration calculation unit when the commercial power supply is normal;
When an abnormality occurs in the commercial power supply, an undervoltage calculator that calculates an undervoltage from the calculation result of the integral calculator and the integral value stored in the integral value storage;
A compensation waveform storage unit that stores a number of patterns preliminarily assumed for an undervoltage component calculated by the undervoltage calculation unit;
According to the magnitude of the undervoltage required by the undervoltage calculator, the closest waveform pattern is selected from the waveform patterns stored in the compensation waveform storage, and this waveform pattern is selected next to the uninterruptible power supply. And an output voltage waveform command calculation unit that outputs an output voltage command value of a half cycle.

(6) In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
A reference integral value creation unit that sets the integral value of the output waveform when the commercial power supply is normal as a reference integral value;
An undervoltage calculator that calculates an undervoltage from a calculation result of the integral calculation unit and a reference integral value set in the reference integral value creation unit when an abnormality occurs in the commercial power supply;
A compensation waveform storage unit that stores a number of patterns preliminarily assumed for an undervoltage component calculated by the undervoltage calculation unit;
According to the magnitude of the undervoltage required by the undervoltage calculator, the closest waveform pattern is selected from the waveform patterns stored in the compensation waveform storage, and this waveform pattern is selected next to the uninterruptible power supply. And an output voltage waveform command calculation unit that outputs an output voltage command value of a half cycle.

  As described above, according to the present invention, a complicated calculation for preventing the magnetism of the transformer is unnecessary, and further, a change in supply power (undervoltage) in switching from a commercial power supply to an uninterruptible power supply is reduced. A standby uninterruptible power supply system can be realized.

  Specifically, according to the configuration of the first aspect, since the waveform of the half cycle in which an abnormality has occurred in the commercial power supply is used as the voltage command of the next half cycle, the calculation of the compensation voltage waveform is unnecessary, and only the memory circuit Can be configured.

  According to the configuration of claim 2, since the effective value of the half cycle in which an abnormality has occurred in the commercial power supply is multiplied by the voltage command of the next half cycle to obtain a voltage command, only the effective value calculation is performed without performing a complicated calculation. Can be configured.

  According to the configuration of claim 3, in order to compensate for the shortage of voltage due to switching delay within a half cycle in which an abnormality has occurred in the commercial power supply, the effective value of supply voltage for each half cycle to the load does not decrease, and It takes no time to return to the effective voltage value.

  According to the configuration of the fourth aspect, the integration circuit in the third aspect is omitted, and the integral value is kept constant, so that the control circuit can be simplified.

  According to the configuration of claim 5, the integrated value of the next half cycle and the integrated value of the next half cycle are the same without reducing the voltage effective value of the next half cycle in which the commercial power supply abnormality has occurred. It becomes.

  According to the configuration of the sixth aspect, the control circuit can be simplified by omitting the integral calculation unit of the fifth aspect and keeping the integral value constant.

(Embodiment 1)
FIG. 1 shows a configuration diagram of a standby uninterruptible power supply system of the present embodiment. 12 is different from FIG. 12 in that a voltage waveform on the load side is always stored, and this voltage waveform is used as an output voltage command in the next half cycle when a power supply abnormality occurs.

  The output voltage detector 10 detects the input voltage waveform of the transformer 3, and the load-side voltage waveform storage unit 11 stores and updates the sampling data string of the load-side voltage waveform for each half cycle from the detected waveform. When the commercial power source 1 is normal, the output voltage waveform command calculation unit 12 gives the detection waveform of the output voltage detection unit 10 as it is to the power converter control unit 7 as an output voltage command (sine wave), and an abnormality occurs in the commercial power source 1 Then, the voltage waveform stored and updated in the load-side voltage waveform storage unit 11 is given to the power converter control unit 7 as an output voltage command for the next half cycle.

  Whether the commercial power supply 1 is normal or abnormal is determined by the output voltage waveform command calculation unit 12 using a monitoring signal from the system voltage monitoring unit 6 or from a detection waveform of the output voltage detection unit 10.

  FIG. 2 shows an example of a compensation voltage waveform when a commercial power supply abnormality occurs. When the commercial power supply 1 fails at time t1, power supply by the power converter 8 is started from time t2. This switching causes a delay from time t 1 to time t 2, and a bias current flows through the transformer 3. The same voltage waveform as this half cycle is stored in the load side voltage waveform storage unit 11, and the output voltage waveform command calculation unit 12 uses the voltage waveform obtained by inverting the voltage waveform as the output voltage waveform command for the next half cycle. .

  Therefore, the magnetic bias of the transformer that occurs at the time of switching from the commercial power supply to the uninterruptible power supply is canceled in the next half cycle, and the magnetic bias of the transformer can be prevented. In addition, the adjustment of the output voltage waveform for preventing the bias is performed by using the half-cycle sampling data stored in the load-side voltage waveform storage unit 11 as it is, so that a complicated calculation as in the prior art becomes unnecessary.

(Embodiment 2)
FIG. 3 shows a configuration diagram of the standby uninterruptible power supply system of the present embodiment. 1 differs from FIG. 1 in that an effective value calculation unit 13 is provided instead of the load side voltage waveform storage unit 11 in FIG.

  The effective value calculation unit 13 always calculates the effective value for each half cycle. As shown in FIG. 4, the output voltage waveform command calculation unit 12 multiplies the output voltage amplitude by the effective voltage value of the half cycle in which the power supply abnormality has occurred in the next half cycle in which the power supply abnormality has occurred. Is the command value.

  If the switching delay due to power supply abnormality occurs beyond the end timing of the half cycle, the effective value calculation is added or subtracted with the end timing in between.

  Also in this embodiment, the magnetic bias of the transformer generated when switching from the commercial power supply to the uninterruptible power supply is canceled in the next half cycle, and the magnetic bias of the transformer can be prevented. Further, the adjustment of the output voltage waveform for preventing the bias magnetism is performed only by the effective value calculation, and the conventional complicated calculation becomes unnecessary.

(Embodiment 3)
FIG. 5 shows a configuration diagram of the standby uninterruptible power supply system of the present embodiment. In the present embodiment, in addition to preventing the bias of the transformer, the effective value of the supply voltage to the load is reduced (change in supply power) by compensating for the shortage of the supply voltage to the load within a half cycle when the power supply abnormality occurs. To compensate.

  1 differs from FIG. 1 in that the integration calculation unit 14 that integrates the detection voltage of the output voltage detection unit 10 every half cycle and the calculation result of the integration calculation unit 14 when the commercial power supply is normal are stored and updated. The integrated value storage unit 15 is provided.

  In this configuration, the output voltage waveform command calculation unit 12 compares the calculation result of the integration calculation unit 14 and the integration value stored in the integration value storage unit 15 when an abnormality occurs in the commercial power supply, and outputs the output voltage due to the switching delay. The shortage of the integral value is calculated, and an output voltage waveform command is generated by adding and compensating this shortage to the voltage waveform output by the power converter 8 immediately after the abnormality of the commercial power supply.

  FIG. 6 shows an example of operation waveforms. In FIG. 6, the power supply voltage waveform indicates the detection waveform of the power supply voltage, the output voltage waveform indicates the detection waveform of the output voltage detection unit 10, and the integrated waveform of the output voltage indicates the calculation result of the integration calculation unit 14. When an abnormality occurs in the commercial power source at time tl, it is assumed that power feeding by the power converter starts from time t2 after a delay in switching from power feeding by the commercial power source to power feeding by the power converter. As a result, the voltage corresponding to the shaded portion A of the output voltage waveform is insufficient with respect to the output voltage waveform (the broken line portion of the output voltage waveform between times tl and t2) when there is no abnormality in the commercial voltage.

  That is, the output waveform integrated waveform amplitude (solid line portion of the output voltage integrated waveform between times t1 and t2) in the middle of the half cycle in which the power supply abnormality occurs is the output in the half cycle before the power supply abnormality occurs. The voltage decreases with respect to the integrated waveform amplitude of the voltage (the broken line portion of the integrated waveform of the output voltage between times tl and t2). An insufficiency of the output voltage integrated value due to power supply abnormality is calculated from the amplitude error of this voltage integrated waveform, and an output voltage waveform command (in the shaded portion B of the output voltage waveform is set to compensate for this insufficiency between times t2 and t3. Increase) to prevent a decrease in the effective value of the supply voltage to the load.

  Here, when the shortage of the output voltage integral value due to power supply abnormality is compensated between time t2 and t3, the shortage is compensated as shown by the broken line portion of the integrated waveform of the output voltage between time t2 and t3 (as an example of the method) When the shortage is evenly distributed and raised between times t2 and t3), the output voltage increases rapidly (an example of a waveform is shown in FIG. 7). In the present embodiment, the integrated value is increased as indicated by the solid line portion of the integrated waveform of the output voltage at time t2-t3 (as an example of the method, the shortage is increased by using soft start so as to compensate by time t3). .

  When a switching delay due to a power supply abnormality occurs beyond the end timing of a half cycle, the transformer is prevented from being demagnetized by calculating the integral value over the next half cycle and compensating for the shortage.

  According to this embodiment, in addition to preventing the magnetism of the transformer, the supply voltage effective value for each half cycle to the load is compensated for the shortage of voltage due to the switching delay within the half cycle in which the abnormality occurred in the commercial power supply. Does not decrease, and the time delay until the voltage effective value before switching is restored is within a half cycle.

(Embodiment 4)
FIG. 8 shows a configuration diagram of the standby uninterruptible power supply system of this embodiment. In the present embodiment, a reference integral value creation unit 16 is provided instead of the integral value storage unit 15 in FIG.

  The reference integral value creation unit 16 creates a predetermined reference integral value instead of storing and updating the output waveform when the commercial power supply is normal in the integral value storage unit 15 as the calculation result of the integration calculation unit 14. To set. The output voltage waveform command calculation unit 12 compares the calculation result of the integration calculation unit 14 with the value set in the reference integral value creation unit 16 when an abnormality occurs in the commercial power supply, and the output voltage integration due to the switching delay. The shortage of the value is calculated, and an output voltage waveform command is generated by adding and compensating the shortage to the voltage waveform output from the power converter 8 immediately after the abnormality of the commercial power supply.

  According to the present embodiment, in addition to preventing the bias magnetism of the transformer, the storage update process of the integral calculation result by the integral value storage unit 15 of the third embodiment is not required, and the integral value is set to the reference value (constant). Thus, the arithmetic processing can be simplified.

(Embodiment 5)
FIG. 9 shows a configuration diagram of the standby uninterruptible power supply system of the present embodiment. In the present embodiment, in addition to the circuit configuration of FIG. 5, an undervoltage calculation unit 17 and a compensation waveform storage unit 18 are provided, and the voltage effective value of the next half cycle when a commercial power supply abnormality occurs is obtained as a half of the normal commercial power supply. Compensation is made so as not to decrease compared with the effective voltage value in the cycle.

  The undervoltage calculating unit 17 calculates the shortage of the supply voltage to the load from the shortage of the output voltage integrated value due to the power supply abnormality obtained from the calculation result of the integration calculating unit 14 and the value of the integral value storage unit 15. The compensation waveform storage unit 18 is set as a number pattern that assumes the shortage of the supply voltage calculated by the undervoltage calculation unit 17 in advance, and these patterns are supplied from the power converter in the next half cycle when the commercial power supply abnormality occurs. Save it as a voltage waveform to be output.

  The output voltage waveform command calculation unit 12 is the closest among several waveform patterns stored in the compensation waveform storage unit 18 according to the shortage of the supply voltage obtained by the undervoltage calculation unit 17. A waveform pattern is selected, and this waveform pattern is used as an output voltage command value for the next half cycle. An example of the compensation waveform at this time is shown in FIG. Note that the shortage voltage due to switching is set to a compensated output voltage waveform command as in the first embodiment.

  According to the present embodiment, in addition to preventing the bias of the transformer, in order not to lower the effective voltage value of the next half cycle in which the commercial power supply abnormality has occurred, the integral value of the half cycle in which the commercial power supply abnormality has occurred, The integral value of the half cycle is the same.

(Embodiment 6)
FIG. 11 shows a configuration diagram of the standby uninterruptible power supply system of the present embodiment. In this embodiment, in the circuit configuration of FIG. 9, instead of the integral value storage unit 15, the reference integral value creation unit 16 of FIG. 8 is used. A reference integral value set in advance is used.

  According to this embodiment, the control circuit can be simplified by omitting the integral calculation unit of the fifth embodiment and keeping the integral value constant.

1 is a configuration diagram of a standby uninterruptible power supply system showing Embodiment 1 of the present invention. 4 is a compensation voltage waveform example when a commercial power supply abnormality occurs in the first embodiment. The block diagram of the standby uninterruptible power supply system which shows Embodiment 2 of this invention. 10 is a compensation voltage waveform example when a commercial power supply abnormality occurs in the second embodiment. The block diagram of the standby uninterruptible power supply system which shows Embodiment 3 of this invention. 10 is a compensation voltage waveform example when a commercial power supply abnormality occurs in the third embodiment. 10 is a compensation voltage waveform example when a commercial power supply abnormality occurs in the third embodiment. The block diagram of the standby uninterruptible power supply system which shows Embodiment 4 of this invention. The block diagram of the standby uninterruptible power supply system which shows Embodiment 5 of this invention. 10 is a compensation voltage waveform example when a commercial power supply abnormality occurs in the fifth embodiment. The block diagram of the standby uninterruptible power supply system which shows Embodiment 6 of this invention. The block diagram of the conventional standby type uninterruptible power supply system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 High speed switch 3 Transformer 4 Load 5 Power supply voltage detection part 6 System voltage monitoring part 7 Power converter control part 8 Power converter 9 Power storage element 10 Output voltage detection part 11 Load side voltage waveform memory | storage part 12 Output voltage waveform Command calculation unit 13 RMS value calculation unit 14 Integral calculation unit 15 Integral value storage unit 16 Reference integral value creation unit 17 Undervoltage calculation unit 18 Compensation waveform storage unit

Claims (6)

In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
A load-side voltage waveform storage unit for storing a load-side voltage waveform for each half cycle;
When the commercial power supply is normal, the detection waveform of the output voltage detection unit is used as an output voltage command as it is, and when a power supply abnormality occurs, the voltage waveform stored and updated in the load side voltage waveform storage unit is updated to the next of the uninterruptible power supply . A standby uninterruptible power supply system, comprising: an output voltage waveform command calculation unit that outputs a half-cycle output voltage command value. In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An effective value calculation unit for calculating an effective value of the load-side voltage waveform for each half cycle;
When the commercial power supply is normal, the output voltage detection unit uses the detected waveform as it is as the output voltage command, and when a power supply abnormality occurs, the output voltage amplitude is multiplied by the voltage effective value calculated by the effective value calculation unit as a coefficient. A standby uninterruptible power supply system, comprising: an output voltage waveform command calculation unit that uses a voltage waveform as an output voltage command value for the next half cycle of the uninterruptible power supply. In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
An integration value storage unit for storing and updating the calculation result of the integration calculation unit when the commercial power supply is normal;
When an abnormality occurs in the commercial power supply, an undervoltage is calculated from the calculation result of the integral calculation unit until the uninterruptible power supply starts to supply power to the load and the integral value stored in the integral value storage unit, A standby type characterized by comprising an output voltage waveform command calculation unit that uses an output voltage waveform obtained by adding an undervoltage component to an output voltage waveform as an output voltage command value when power supply from an uninterruptible power supply to a load is started Uninterruptible power system. In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
A reference integral value creation unit that sets the integral value of the output waveform when the commercial power supply is normal as a reference integral value;
When an abnormality occurs in the commercial power supply, the undervoltage is calculated from the calculation result of the integration calculation unit until the power supply from the uninterruptible power supply to the load and the reference integral value set in the reference integral value creation unit are calculated. And an output voltage waveform command calculation unit that uses the output voltage waveform obtained by adding the insufficient voltage to the output voltage waveform as an output voltage command value when power is supplied from the uninterruptible power supply to the load. Standby uninterruptible power supply system. In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
An integration value storage unit for storing and updating the calculation result of the integration calculation unit when the commercial power supply is normal;
When an abnormality occurs in the commercial power supply, an undervoltage calculator that calculates an undervoltage from the calculation result of the integral calculator and the integral value stored in the integral value storage;
A compensation waveform storage unit that stores a number of patterns preliminarily assumed for an undervoltage component calculated by the undervoltage calculation unit;
According to the magnitude of the undervoltage required by the undervoltage calculator, the closest waveform pattern is selected from the waveform patterns stored in the compensation waveform storage, and this waveform pattern is selected next to the uninterruptible power supply. A standby uninterruptible power supply system, comprising: an output voltage waveform command calculation unit that outputs an output voltage command value of a half cycle. In a standby uninterruptible power supply system that always feeds a load from a commercial power supply via a high-speed switch, disconnects the high-speed switch when the commercial power supply is abnormal, and starts feeding the load from the uninterruptible power supply,
An output voltage detector that detects a load-side voltage waveform for each half cycle;
An integration calculation unit that integrates the detection voltage of the output voltage detection unit every half cycle;
A reference integral value creation unit that sets the integral value of the output waveform when the commercial power supply is normal as a reference integral value;
An undervoltage calculator that calculates an undervoltage from a calculation result of the integral calculation unit and a reference integral value set in the reference integral value creation unit when an abnormality occurs in the commercial power supply;
A compensation waveform storage unit that stores a number of patterns preliminarily assumed for an undervoltage component calculated by the undervoltage calculation unit;
According to the magnitude of the undervoltage required by the undervoltage calculator, the closest waveform pattern is selected from the waveform patterns stored in the compensation waveform storage, and this waveform pattern is selected next to the uninterruptible power supply. A standby uninterruptible power supply system, comprising: an output voltage waveform command calculation unit that outputs an output voltage command value of a half cycle.

Images