JP2006166526A - Provision for preventing instantaneous voltage drop - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compensate the lowering of power factor and voltage drop of a load system due to a reactor constituting a provision for preventing instantaneous voltage drop installed between a power system and its load system. <P>SOLUTION: The provision for preventing instantaneous voltage drop 20 comprises a switch 21, a reactor 22, and a parallel inverter 24 and when a power system 1 is sound, a parallel inverter 23 feeds a compensation current Iconv for bringing the voltage across a load apparatus 2 to a predetermined level thus improving the power factor when viewed from the power system 1 while sustaining the voltage across the load apparatus 2 at a predetermined level. When the power system 1 enters power failure state subsequently, the parallel inverter 23 supplies power to the load apparatus 2. Energy stored in the reactor 22 functions to sustain the voltage across the load apparatus 2 in a substantially normal state even at the time of transient. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an instantaneous voltage drop countermeasure device installed between a power system such as a commercial power supply and its load equipment.

  In recent years, load devices, such as power electronics devices, computer devices, and electronic devices, which are easily affected by voltage fluctuations in the power system as a power source thereof have increased. Therefore, when the power system is a high-voltage system, the load device In addition, a backup power source such as a private power generation facility is installed, and an instantaneous voltage drop countermeasure device is provided between the power system and the load device to disconnect the load device from the power system in the event of a power failure or voltage drop of the power system. It has been.

  FIG. 11 is a circuit configuration diagram showing a conventional example of this type of instantaneous voltage drop countermeasure device, which has the same configuration as the circuit described in Non-Patent Document 1 below.

  That is, in FIG. 11, 1 is an electric power system such as a commercial power source, 10 is an instantaneous voltage drop countermeasure device inserted between the electric power system 1 and a load system consisting of the load device 2, the private power generation facility 3, etc. The instantaneous voltage drop countermeasure device 10 includes a breaker 11 on the power system 1 side, a reactor 12, a thyristor switch (hereinafter also referred to as a thyristor SW) 13, a breaker 14 on the load system side, an auxiliary transformer 15, And a thyristor SW control circuit 16 for controlling the operation of the thyristor SW 13 based on the voltage value of the power system 1 detected by the auxiliary transformer 15.

  The operation of the conventional instantaneous voltage drop countermeasure device shown in FIG. 11 will be described below with reference to the operation waveform diagram shown in FIG.

First, since the voltage Vs of the power system 1 is healthy until immediately before time t ₀ shown in FIG. A current Is flows from the power system 1 to the load device 2 through the SW 13 and the closed circuit breaker 14.

Next, at time t ₀ , when the power system 1 falls into a power outage state for some reason, the voltage Vs of the power system 1 becomes zero from this time. The voltage Vr changes as shown in the figure from time t ₀ , and the current Is for maintaining the voltage Vload across the load device 2 in a substantially normal state continues to flow for a period of several milliseconds due to the voltage Vr.

Further, the voltage Vs is zero state of the above-detected thyristor SW control circuit 16 via an auxiliary transformer 15, by sending an OFF command signal to the thyristor SW13, current Is at time t ₁ becomes zero Then, the thyristor SW13 enters a cut-off state, and the thyristor SW13 in the cut-off state thereafter disconnects the power system 1 from the load system including the load equipment 2, the private power generation equipment 3, and the like, and the load equipment 2 from the private power generation equipment 3 In this state, power is supplied to.

In this instantaneous voltage drop countermeasure device 10, the thyristor SW 13 can perform high-speed interruption within a half cycle of the voltage Vs of the power system 1, so that the circuit breaker 11 and the circuit breaker 14 fall from the closed state to the power failure state of the power system 1. Even if it takes time to shift to the open circuit state by the shut-off command issued immediately after this time, this time does not affect the load system.
Japanese Patent Laid-Open No. 2000-287458 (page 5, FIG. 1, etc.). Sugawara et al., “Instantaneous power failure countermeasure device using thyristor switch”, Industrial Electric Power Application Study Group, IEA-01-6, March 16, 2001, Institute of Electrical Engineers of Japan.

  In the instantaneous voltage drop countermeasure device 10 shown in FIG. 11, in order to perform the above-described operation, for example, when the percent impedance (% Z) of the reactor 12 is set to 30% and the load device 2 is a pure resistance load, As shown in the operation waveform diagram of FIG. 12 and the vector diagram of FIG. 13, the voltage Vs across the reactor 12 is 30 when the voltage Vs of the power system 1 is the rated voltage (100%) and the current Is is the rated current (100%). The phase difference between the voltage Vs and the current Is at this time is 17 ° (electrical angle). Therefore, the power factor viewed from the power system 1 is about 0.96, and the voltage Vload across the load device 2 is 95%. As a result, there is a problem in that the power system 1 caused by the reactor 12 when the power system 1 is healthy causes a power factor reduction as viewed from the power system 1 and a voltage drop across the load device 2.

  In order to solve the above problem, for example, in the circuit example disclosed in Patent Document 1, a series inverter is provided instead of the reactor 12 in FIG. 11, and the voltage drop of the power system 1 is compensated by this series inverter. However, since this series inverter shares a part of the active power to the load equipment, its output capacity increases, and further, a high-speed response is required in a wide output voltage range. There was a new problem that the voltage drop countermeasure device was increased in size and increased in price.

  An object of the present invention is to provide an instantaneous voltage drop countermeasure device that solves the above problems.

  The instantaneous voltage drop countermeasure device according to the first aspect of the present invention includes a switch, a reactor for compensating instantaneous voltage drop, and a parallel inverter. Between the power system such as a commercial power supply and its load device, the switch, the reactor, Are connected to the load device via a connected reactor or the like provided on the output side of the inverter, and when the power system is healthy, The parallel inverter is operated based on a reactive current command value as a compensation current command value derived from an adjustment calculation result that makes a deviation between a both-end voltage and a predetermined output voltage set value zero.

  The instantaneous voltage drop countermeasure device of the second invention comprises a switch, a reactor for compensating the instantaneous voltage drop, and a parallel inverter, and the switch and the reactor are connected between a power system such as a commercial power source and its load device. Connect both ends of the circuit connected in series, and connect the parallel inverter to the load device via a connected reactor or the like provided on the output side of the inverter, when the power system is healthy, to the load device The parallel inverter is operated based on a compensation current command value derived to maintain a desired voltage across the load device from each component obtained by decomposing the current into an active current component and a reactive current component. Features.

  The instantaneous voltage drop countermeasure device of the third invention comprises a switch, a reactor for compensating the instantaneous voltage drop, and a parallel inverter, and the switch and the reactor are provided between a power system such as a commercial power source and the load device. Connect both ends of a circuit connected in series, and connect the parallel inverter to the load device via a connected reactor or the like provided on the output side of the inverter. When the power system is healthy, both ends of the load device A reactive current command value as a compensation current command value derived from an adjustment calculation result that makes a deviation between a voltage and a predetermined output voltage setting value zero, and a current to the load device into an active current component and a reactive current component Based on a new compensation current command value obtained by adding a compensation current command value derived to maintain the desired voltage across the load device from each decomposed component. And wherein the operating the parallel inverter.

  According to a fourth invention, in the instantaneous voltage drop countermeasure device according to the first to third inventions, a phase advance capacitor is added between the parallel inverter and a load device.

A fifth invention is the instantaneous voltage drop countermeasure device of the first to fourth inventions,
When an instantaneous voltage drop occurs in the power system, the switch is shifted from a closed state to an open state, and the parallel inverter is operated as a power source for the load device.

  According to the instantaneous voltage drop countermeasure device of the present invention, as will be described later, the parallel inverter eliminates the power factor drop and the voltage drop to the load device as seen from the power system caused by the reactor. Power can be supplied to load equipment.

  FIG. 1 is a circuit configuration diagram of an instantaneous voltage drop countermeasure device showing a first embodiment of the present invention. In this figure, components having the same functions as those of the conventional circuit configuration shown in FIG. It is attached.

  That is, the instantaneous voltage drop countermeasure device 20 shown in FIG. 1 includes a switch 21 having a high-speed cutoff function such as a thyristor SW, a reactor 22 manufactured with the same specifications as the reactor 12, and any of the parallel inverters 23 to 25. Or one.

  The operation of the instantaneous voltage drop countermeasure device 20 will be described below with reference to the operation vector diagram shown in FIG.

FIG. 2 (a) shows a vector diagram when the parallel inverter in the instantaneous voltage drop countermeasure device 20 is not operated. At this time, the current Is flowing from the power system 1 to the instantaneous voltage drop countermeasure device 20 and the instantaneous voltage drop countermeasure device 20 are shown. Is equal to the current I _L to the load device 2, and these currents are in a lagging phase with respect to the voltage Vs of the power system 1. As a result, the both-ends voltage Vload of the load device 2 is a value that is lower than the voltage Vs as shown in the figure.

  On the other hand, FIG. 2B shows a vector diagram when the parallel inverter in the instantaneous voltage drop countermeasure device 20 is operated. At this time, by injecting a compensation current Iconv having a phase and amplitude as shown from the parallel inverter. The voltage Vs of the power system 1 and the voltage Vload across the load device 2 can be made substantially equal, and the power factor viewed from the power system 1 can also be improved.

  FIG. 3 is a circuit configuration diagram of an instantaneous voltage drop countermeasure device showing a second embodiment of the present invention. In this figure, components having the same functions as those of the circuit configuration shown in FIG. ing. That is, the instantaneous voltage drop countermeasure device 30 shown in FIG. 3 is different from the instantaneous voltage drop countermeasure device 20 shown in FIG. 1 in that a phase advance capacitor 31 is provided.

  In general, the load device 2 has a delay power factor, and the voltage across the load device 2 decreases as described above in order to take a reactive power with a delay. On the other hand, the reactive power of the leading is output from the parallel inverter, but the instantaneous voltage drop countermeasure device 30 assumes the reactive power amount of the delay that the load device 2 takes in advance, and all or part of it is assumed. A phase advance capacitor 31 having a capacity to compensate is provided. Accordingly, when the capacity of the load device 2 becomes light and the reactive power taken by the phase advance capacitor 31 becomes excessive, the parallel inverter may be operated so as to take the reactive power delayed so as to cancel it. . As a result, the average reactive power to be output by the parallel inverter is reduced, the operation efficiency is improved, and the capacity of the parallel inverter can be reduced.

  FIG. 4 is a circuit configuration diagram of the instantaneous voltage drop countermeasure device according to the first embodiment of the present invention. The instantaneous voltage drop countermeasure device 20 includes a switch 21, a reactor 22, an inverter circuit 23a, and an interconnected reactor 23b. , A DC capacitor 23 c, a parallel inverter 23 including a control circuit 230, and an auxiliary transformer 26. Here, the interconnected reactor 23b may be a transformer having a considerable leakage inductance, and may be used in combination with both the transformer and the reactor.

FIG. 5 is a detailed circuit configuration diagram of the control circuit 230 shown in FIG. 4. The control circuit 230 detects an output voltage setting unit 231 that sets a voltage across the load device 2 and a voltage across the load device 2. A voltage detector 232 that converts an AC voltage obtained from the auxiliary transformer 26 into a corresponding DC voltage, and an addition calculator 233 that obtains a deviation between a set value from the output voltage setter 231 and a detected value from the voltage detector 232 And a voltage regulator 234 that performs an adjustment operation to make this deviation zero, and a reactive current command calculation that generates a reactive current command value as a compensation current command value Iconv ^* (alternating current amount) to be described later based on the adjustment calculation result Instrument 235. That is, when the adjustment calculation result has a polarity that increases the voltage across the load device 2, the amplitude is an absolute value of the adjustment calculation result at a phase advanced by 90 ° with respect to the phase of the AC voltage from the auxiliary transformer 26. The reactive current command value is a value proportional to the reactive current command value, and if the adjustment calculation result has a polarity that reduces the voltage across the load device 2, the phase of the AC voltage from the auxiliary transformer 26 is The reactive current command value is a value (AC amount) whose amplitude is 90 ° delayed and proportional to the absolute value of the adjustment calculation result.

  The operation of the instantaneous voltage drop countermeasure device 20 shown in FIG. 4 will be described below.

That is, the parallel inverter 23 shown in FIG. 4 is connected to the power supply system 1 via the reactor 22 when the power system 1 is healthy, and is based on the compensation current command value Iconv ^* as described above from the control circuit 230. By injecting the compensation current Iconv, while maintaining the voltage across the load device 2 at the set value of the output voltage setter 231, the power factor seen from the power system 1 is improved, and the interconnection reactor 23b and the inverter circuit 23a The DC capacitor 23c is in standby while charging the DC voltage via the. When the power system 1 falls into a power failure state for some reason, the switch 21 in the closed state is shifted to the open state, and the power charged in the DC capacitor 23c is supplied to the load device 2. At this time, a time delay occurs until the switch 21 is actually opened. During this time delay, the energy stored in the reactor 22 maintains the voltage across the load device 2 in a substantially normal state. In order to function, a decrease in the voltage across the load device 2 is suppressed.

  In addition, if it is necessary for the interconnection reactor 23b to have a harmonic suppression function, the requirement can be satisfied by additionally installing a filter capacitor in parallel with this.

  FIG. 6 is a circuit configuration diagram of the instantaneous voltage drop countermeasure device according to the second embodiment of the present invention. The instantaneous voltage drop countermeasure device 20 includes a switch 21, a reactor 22, an inverter circuit 23a, and an interconnected reactor 23b. , A DC inverter 23c, a parallel inverter 24 composed of a control circuit 240, or a parallel inverter 25 composed of an inverter circuit 23a, a connected reactor 23b, a DC capacitor 23c, a control circuit 250, an auxiliary transformer 26, CT (instrument transformer) 27.

FIG. 7 is a detailed circuit configuration diagram of the control circuit 240 shown in FIG. 6. This control circuit 240 includes a CT 27 for the phase of the AC voltage obtained from the auxiliary transformer 26 that detects the voltage across the load device 2. An effective / reactive current calculator 241 that decomposes the current to the load device 2 into a valid / inactive current component Iq and an active current component Ip, and suppresses fluctuations in the voltage across the load device 2 with respect to fluctuations in the effective current component Ip. In order to achieve this, the following equation 1 is calculated, and a calculator 242 that outputs the calculation result as an active current compensation component Ip2, and the effective current compensation component Ip2 and the reactive current component Iq are obtained from the auxiliary transformer 26. A compensation current command calculator 243 for deriving a compensation current command value Iconv ^* (amount of alternating current) based on the phase of the AC voltage to be generated.
[Equation 1]
Ip2 = {1- [1- (Xr · Ip) ² ] ^1/2 } / Xr
Here, the voltage Vs of the power system 1 is a rated value (= 1), and Xr indicates the percent impedance (% Z) of the reactor 22.

That is, in the compensation current command value calculator 243, all of the reactive current component Iq is advanced by 90 ° with respect to the phase of the AC voltage from the auxiliary transformer 26, and its amplitude is a value proportional to the value of Iq (AC amount). ) And the phase of the AC voltage from the auxiliary transformer 26, the phase of which is opposite to that of the AC voltage and the value of which is proportional to the value of Iq2 (AC amount) is output as the compensation current command value Iconv ^*. ing.

  The operation of the instantaneous voltage drop countermeasure device 20 shown in FIG. 6 will be described below.

That is, the parallel inverter 24 shown in FIG. 6 is connected to the power supply system 1 via the reactor 22 when the power system 1 is healthy, and is based on the compensation current command value Iconv ^* as described above from the control circuit 240. By injecting the compensation current Iconv, the fluctuation is suppressed while maintaining the voltage across the load device 2 at a substantially rated value, the power factor seen from the power system 1 is improved, and the interconnection reactor 23b and the inverter circuit 23a The DC capacitor 23c is in standby while charging the DC voltage via the. When the power system 1 falls into a power failure state for some reason, the switch 21 in the closed state is shifted to the open state, and the power charged in the DC capacitor 23c is supplied to the load device 2. At this time, a time delay occurs until the switch 21 is actually opened. During this time delay, the energy stored in the reactor 22 maintains the voltage across the load device 2 in a substantially normal state. In order to function, a decrease in the voltage across the load device 2 is suppressed.

  In addition, if it is necessary for the interconnection reactor 23b to have a harmonic suppression function, the requirement can be satisfied by additionally installing a filter capacitor in parallel with this.

  FIG. 8 is a detailed circuit configuration diagram of the control circuit 250 shown in FIG. 6. The control circuit 250 includes the control circuit 230 shown in FIG. 5, the control circuit 240 shown in FIG. And.

Therefore, the parallel inverter 25 shown in FIG. 6 is connected to the power supply system 1 via the reactor 22 when the power system 1 is healthy, and the control circuit 230 from the control circuit 250 and the control circuit 240 as described above. By injecting a compensation current Iconv based on a new compensation current command value Iconv ^* obtained by adding the respective compensation current command values, fluctuations are suppressed while maintaining the voltage across the load device 2 at the set value of the output voltage setter 231. And while improving the power factor seen from the electric power grid | system 1, it waits, charging the DC voltage to the DC capacitor 23c via the interconnection reactor 23b and the inverter circuit 23a. When the power system 1 falls into a power failure state for some reason, the switch 21 in the closed state is shifted to the open state, and the power charged in the DC capacitor 23c is supplied to the load device 2. At this time, a time delay occurs until the switch 21 is actually opened. During this time delay, the energy stored in the reactor 22 maintains the voltage across the load device 2 in a substantially normal state. In order to function, a decrease in the voltage across the load device 2 is suppressed.

  In addition, if it is necessary for the interconnection reactor 23b to have a harmonic suppression function, the requirement can be satisfied by additionally installing a filter capacitor in parallel with this.

  FIG. 9 is a circuit diagram of an instantaneous voltage drop countermeasure device showing a third embodiment of the present invention. The instantaneous voltage drop countermeasure device 40 includes a switch 21, a reactor 22, a parallel inverter 23, an auxiliary transformer. 26 and a DC power source 41.

  That is, the instantaneous voltage drop countermeasure device 40 is different from the instantaneous voltage drop countermeasure device 20 including the parallel inverter 23 shown in FIG. 4 in that a DC power source 41 including a storage battery is provided on the DC side of the inverter circuit 23a. That is.

  With this DC power supply 41, after the power system 1 falls into a power failure state for some reason, the period during which power is supplied from the parallel inverter 23 to the load device 2 can be made longer.

  FIG. 10 is a circuit configuration diagram of an instantaneous voltage drop countermeasure device showing a fourth embodiment of the present invention. The instantaneous voltage drop countermeasure device 50 includes a switch 21, a reactor 22, a parallel inverter 24, an auxiliary transformer. 26, CT 27, and DC power supply 41.

  That is, the instantaneous voltage drop countermeasure device 50 is different from the instantaneous voltage drop countermeasure device 20 including the parallel inverter 24 shown in FIG. 6 in that a DC power source 41 including a storage battery is provided on the DC side of the inverter circuit 23a. That is.

  With this DC power supply 41, after the power system 1 falls into a power failure state for some reason, the period during which power is supplied from the parallel inverter 24 to the load device 2 can be made longer.

1 is a circuit configuration diagram of an instantaneous voltage drop countermeasure device showing a first embodiment of the present invention. Vector diagram explaining the operation of FIG. The circuit block diagram of the instantaneous voltage drop countermeasure device which shows 2nd Embodiment of this invention 1 is a circuit configuration diagram of an instantaneous voltage drop countermeasure device showing a first embodiment of the present invention. Partial detailed circuit configuration diagram of FIG. Circuit configuration diagram of instantaneous voltage drop countermeasure device showing second embodiment of the present invention Partial detailed circuit configuration diagram of FIG. Partial detailed circuit configuration diagram of FIG. Circuit diagram of an instantaneous voltage drop countermeasure device showing a third embodiment of the present invention Circuit diagram of an instantaneous voltage drop countermeasure device showing a fourth embodiment of the present invention Circuit diagram of instantaneous voltage drop countermeasure device showing conventional example Waveform diagram explaining the operation of FIG. Vector diagram explaining the operation of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power system, 2 ... Load apparatus, 3 ... Private power generation equipment, 10 ... Instantaneous voltage drop countermeasure apparatus, 11 ... Circuit breaker, 12 ... Reactor, 13 ... Thyristor switch, 14 ... Circuit breaker, 15 ... Auxiliary transformer, 16 ... Thyristor SW control circuit, 20, 30, 40, 50 ... Instantaneous voltage drop countermeasure device, 21 ... Switch, 22 ... Reactor, 23-25 ... Parallel inverter, 23a ... Inverter main circuit, 23b ... Linked reactor, 23c ... Capacitor , 26 ... auxiliary transformer, 27 ... CT, 31 ... phase advance capacitor, 41 ... DC power supply, 230, 240, 250 ... control circuit.

Claims (5)

With a switch, a reactor for instantaneous voltage drop compensation and a parallel inverter,
Between a power system such as a commercial power supply and its load equipment, both ends of a circuit formed by connecting the switch and the reactor in series are connected, and a connected reactor including the parallel inverter on the output side of the inverter or Connected to the load device via a transformer or both,
When the power system is healthy, the parallel inverter is based on a reactive current command value as a compensation current command value derived from an adjustment calculation result that makes a deviation between a voltage across the load device and a predetermined output voltage setting value zero. An instantaneous voltage drop countermeasure device characterized by operating With a switch, a reactor for instantaneous voltage drop compensation and a parallel inverter,
Between a power system such as a commercial power supply and its load equipment, both ends of a circuit formed by connecting the switch and the reactor in series are connected, and a connected reactor including the parallel inverter on the output side of the inverter or Connected to the load device via a transformer or both,
When the power system is healthy, a compensation current command derived so that the voltage across the load device maintains a desired value from each component obtained by decomposing the current to the load device into an active current component and a reactive current component An instantaneous voltage drop countermeasure device, wherein the parallel inverter is operated based on a value. With a switch, a reactor for instantaneous voltage drop compensation and a parallel inverter,
Between a power system such as a commercial power supply and its load equipment, both ends of a circuit formed by connecting the switch and the reactor in series are connected, and a connected reactor including the parallel inverter on the output side of the inverter or Connected to the load device via a transformer or both,
When the power system is healthy, the reactive current command value as a compensation current command value derived from the adjustment calculation result that makes the deviation between the both-end voltage of the load device and a predetermined output voltage setting value zero, and to the load device A new compensation current obtained by adding a compensation current command value derived so that the voltage across the load device is maintained at a desired value from each component obtained by decomposing the current of the current into an active current component and a reactive current component An instantaneous voltage drop countermeasure device, wherein the parallel inverter is operated based on a command value. In the instantaneous voltage drop countermeasure device according to any one of claims 1 to 3,
An instantaneous voltage drop countermeasure device, wherein a phase advance capacitor is added between the parallel inverter and a load device. In the instantaneous voltage drop countermeasure device according to any one of claims 1 to 4,
When an instantaneous voltage drop occurs in the power system, the switch is shifted from a closed state to an open state, and the parallel inverter is operated as a power source for the load device.

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