JP2019030052A - Reactive power compensation system and method - Google Patents

Abstract

To provide a reactive power compensation system for suppressing interference between reactive power that a generator outputs and reactive power that a stationary type reactive power compensation device outputs, and a method.SOLUTION: In a reactive power compensation system 7A, reactive power of a system 4 including a generator 5 is adjusted by a stationary type reactive power compensation device 70. The reactive power compensation system comprises: a various electric amount calculation part 711 for calculating a voltage fluctuation amount of the system 4 and first reactive power that the generator 5 outputs; and an output signal generation part 713 which generates an output signal Csvc for controlling second reactive power that the stationary type reactive power compensation device 70 outputs, based on the voltage fluctuation amount and the first reactive power which are calculated by the various electric amount calculation part 711, a bus voltage Vs of the system 4 and an output current ic of the stationary type reactive power compensation device 70. The output signal generation part 713 generates the output signal Csvc in such a manner that interference between the first reactive power and the second reactive power is suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reactive power compensation system and method.

  A power system installed in a limited area is called a “local system”, and an existing wide-area power system is called a “upper system”. The local system is linked to the upper system as necessary, and sells power to the upper system or purchases power from the upper system. Generally, a local system is provided with a turbine power generation system or an engine power generation system having a generator. Such a generator can stabilize the frequency and voltage of the system by adjusting the output power by governor control or by adjusting the output voltage to a constant value by AVR (Automatic Voltage Regulator). Are known.

  When the supply and demand balance of power in the local system changes rapidly, the adjustment of the governor control by the generator and the response speed of AVR is not in time, and the amplitude of the system voltage greatly fluctuates. Therefore, for the purpose of suppressing this fluctuation, an SVC (Static Var Compensator) including a power converter and a DC charging unit is used. The SVC outputs a converter current so as to suppress the amplitude of the system voltage.

  However, when a voltage drop occurs due to the AVR of the generator, the SVC may misrecognize that the voltage drop has occurred due to an increase in load, and may absorb reactive power output by the generator. As a method for preventing such interference with the generator, the abstract of Patent Document 1 states that “the interference operation suppression unit 100 is based on the frequency signal ωs and the variation Cωs, and the system stabilization control and the governor of the generator. It is determined whether or not there is interference with the control, and if there is interference, the time constant of the low-pass filter 72 is reduced to reduce the variation Cωs, thereby reducing the control amount by SVC and preventing interference. It is described.

JP 2009-136640 A

  However, in the SVC disclosed in Patent Document 1, in order to reduce the control amount of the SVC in the case of interference, the interference can be suppressed to some extent. However, since the interference is not prevented, in order to suppress the fluctuation of the system voltage. It seems that it doesn't work well.

  The present invention has been made in view of the above-described problems, and a reactive power compensation system and method capable of suppressing interference between reactive power output from a generator and reactive power output from a static reactive power compensator. The purpose is to provide.

  In order to solve the above problems, a reactive power compensation system according to the present invention is a reactive power compensation system that adjusts reactive power of a system having a generator by a static reactive power compensator. An electric quantity calculation unit for calculating the first reactive power output from the power supply, a voltage fluctuation amount calculated by the electric quantity calculation unit, the first reactive power, the system voltage, and the output current of the static reactive power compensator And an output signal generation unit that generates an output signal for controlling the second reactive power output from the static reactive power compensator. The output signal generation unit includes a first reactive power and a second reactive power. The output signal is generated so as to suppress the interference.

  According to the present invention, an output signal that suppresses interference between the first reactive power output from the generator and the second reactive power output from the static reactive power compensator is generated to control the static reactive power compensator. can do. Thereby, while suppressing the voltage fluctuation of a system | strain, the time which returns to the original state can be shortened.

It is a block diagram of the reactive power compensation system which concerns on 1st Example. It is a schematic waveform diagram which shows a change of reactive power etc. when a load fluctuates. It is a block diagram of the reactive power compensation system which concerns on 2nd Example. It is a schematic waveform diagram which shows a change of reactive power etc. when a load fluctuates. It is a block diagram of the reactive power compensation system which concerns on 3rd Example. It is a schematic circuit diagram of the static reactive power compensator according to the fourth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The reactive power compensation system according to the present embodiment calculates the voltage fluctuation amount of the system and the reactive power of the generator, and generates power based on the voltage fluctuation amount, the reactive power, the system voltage, and the current of the static reactive power compensator. An output signal of the static reactive power compensator is generated so as to suppress interference between the first reactive power output from the machine and the second reactive power output from the static reactive power compensator.

  The first embodiment will be described with reference to FIGS.

  <Configuration of the first embodiment>

  FIG. 1 is a block diagram illustrating an example of a reactive power compensation system 7A according to the present embodiment. The reactive power compensation system 7 </ b> A includes a static reactive power compensation device (SVC) 70 and a control device 71 </ b> A that controls the SVC 70. In other embodiments to be described later, they are referred to as reactive power compensation systems 7B and 7C, but can be referred to as reactive power compensation system 7 unless otherwise distinguished. Similarly, in the embodiment described later, it is referred to as a control device 71B, but can be referred to as the control device 71 unless otherwise distinguished.

  The power system PS has a high-order system 1 (another power system) that is a wide-area main power system, and a local system 3 that includes a bus system 4 connected to the high-order system 1 through a connection line 2. In the local system 3, for example, a generator 5, a load facility (hereinafter also referred to as a load) 6, a reactive power compensation system 7 </ b> A, and the like are connected to the bus system 4.

  The generator 5 is a power generation facility having inertia such as an engine generator and a turbine generator, for example, and supplies electric power used by the load 6 of the local system 3. When surplus power is generated in the local system 3, the power output from the generator 5 is suppressed, or surplus power is transmitted to the upper system 1 through the interconnection line 2 to adjust the power supply / demand balance. To do. When the power of the local system 3 is insufficient, the power used by the load 6 is suppressed, or the power is received from the higher system 1 through the interconnection line 2 to adjust the power supply / demand balance.

  The generator 5 has an AVR 50 and uses the generator end voltage Vg detected by the voltage detector 10 to adjust the value of the generator end voltage Vg.

  The load facility 6 includes various electric devices used in houses, office buildings, factories, and the like. Although illustrated as one load in FIG. 1, the load is usually composed of a plurality of loads.

  As will be described later with reference to FIG. 6, the SVC 70 can be configured to include, for example, a power converter and a DC charging unit. The SVC 70 outputs reactive power Qc as “second reactive power” in accordance with the output signal CSVC generated by the control device 71A so as to suppress the voltage fluctuation ΔVs of the bus system 4 that is a voltage suppression target.

  The control device 71A can be configured to include an electrical quantity calculation unit 711 and an output signal generation unit 713.

  The electrical quantity calculation unit 711 detects the voltage Vs of the bus system 4 with the voltage detector 11, detects the generator current ig with the current detector 12, and detects the SVC current ic with the current detector 13. Then, the electric quantity calculation unit 711 calculates the voltage fluctuation amount ΔVs of the bus system 4 and the generator reactive power Qg from the detected values Vs, ig, ic.

  The output signal generation unit 713 generates an output signal Csvc for instructing the SVC reactive power Qc based on the output signal of the electrical quantity calculation unit 711. First, the output signal generation unit 713 generates a control signal using the detected bus voltage Vs, the calculated voltage fluctuation amount ΔVs, and the generator reactive power Qg so as not to reverse the sign of the generator reactive power Qg. . The output signal Csvc is generated using the control signal, the SVC current ic, the value of the bus voltage Vs, and the phase information. The SVC 70 releases or absorbs the SVC reactive power Qc according to the output signal Csvc.

  Here, the generator reactive power Qg corresponds to “first reactive power”. In the present embodiment, as described above, the output signal Csvc to be supplied to the SVC 60 is generated so that the sign of the generator reactive power Qg and the sign of the SVC reactive power Qc are not reversed. In other words, in this embodiment, the output signal Csvc is generated so that the sign of the generator reactive power Qg matches the sign of the SVC reactive power Qc. However, the sign match here includes 0. When the codes match, not only a combination of a positive code and a positive code but also a combination of a positive code and 0 is included.

  <Operation of First Embodiment>

  Next, the operation of the present embodiment will be described with reference to FIG. In FIG. 2, the waveform diagram according to the present embodiment (solid line) is compared with the waveform diagram of the comparative example (dotted line). First, the operation of the present embodiment will be described with reference to the solid line waveform diagram.

  As shown in FIG. 2 (a), it is assumed that the load current iL of the load facility 6 suddenly increases stepwise at time t1.

  When the load current iL increases rapidly, the local system 3 is insufficient in power supply. For this reason, as shown in FIG.2 (b), the voltage Vs of a bus-line system falls from a regulation value after time t1. The generator voltage Vg decreases in conjunction with the decrease in the bus voltage Vs. When the voltage detector 10 detects a decrease in the generator voltage Vg, the AVR 50 operates to return the generator voltage Vg to the target value. Thereby, as shown in FIG.2 (c), the reactive power Qg of the generator 5 increases.

  Since the generator reactive power Qg continues to increase as the bus voltage Vs decreases, the decrease in the bus voltage Vs stops at time t2. At time t2, the bus voltage Vs starts to increase and returns to the specified value at time t3. As the bus voltage Vs returns to the specified value, the generator reactive power Qg also decreases after time t2.

  FIG. 2D shows the voltage fluctuation amount ΔVs of the bus system 4, and takes a negative value from time t1 to time t2, and takes a positive value from time t2 to time t3.

  FIG. 2 (e) shows a change in the reactive power Qc of the SVC 70. The output signal generation unit 713 that controls the SVC reactive power Qc is a positive control signal from the bus voltage Vs that decreases below a specified value, the voltage fluctuation amount ΔVs, and the generator reactive power Qg that increases from time t1 to time t2. Is generated. By giving the output signal Csvc generated using this positive control signal to the SVC 70, the reactive power Qc output from the SVC 70 becomes positive, and operates to suppress voltage fluctuations in the same manner as the reactive power Qg of the generator 5.

  From time t2 to time t3, the sign of the voltage fluctuation amount ΔVs is inverted from negative to positive, but since the bus voltage Vs is negative and the generator reactive power Qg is positive, the output signal generation unit 713 Subsequently, a positive control signal is generated. Accordingly, the reactive power Qc of the SVC 70 is positive, similar to the time t1 to the time t2, and operates so as to suppress voltage fluctuations as with the generator 5.

  <Comparative example>

  Next, a comparative example indicated by a dotted line in FIG. 2 will be described. The comparative example is at least different from the configuration of the present embodiment in that the current detector 12 is not provided. Therefore, in the comparative example, since the generator reactive power Qg cannot be calculated, an output signal to the SVC 70 is generated without considering the generator reactive power Qg.

  The condition that the load current iL of the load facility 6 rapidly increases stepwise at time t1 is the same as in the present embodiment.

  As shown in FIG. 2 (d), the voltage fluctuation amount ΔVs decreases from zero to negative from time t1, then increases and returns to zero at time t2. Also in the case of the comparative example, the output signal generation unit 713 generates the control signal so as to suppress the voltage fluctuation ΔVs, so that the SVC reactive power Qc as illustrated in FIG.

  After time t2, as shown in FIG. 2 (d), the voltage fluctuation amount ΔVs turns to a positive value. In the comparative example, the SVC reactive power Qc becomes negative (absorbed). At this time, since the bus voltage Vs is negative and the generator reactive power Qg is positive (released), the SVC 70 inhibits voltage fluctuation suppression by the generator 5. Therefore, in the case of the comparative example, the bus voltage Vs cannot return to the specified value even at the stage of time t3. The bus voltage Vs returns to the specified value at time t4 that is later than time t3.

  <Effect of the first embodiment>

  As described above, according to the present embodiment, using the detected bus voltage Vs, the calculated voltage fluctuation amount ΔVs, and the generator reactive power Qg, the control signal is prevented from being reversed from the sign of the generator reactive power Qg. And the reactive power Qc is output from the SVC 70. Thereby, it can suppress that the reactive power Qc of SVC70 and the reactive power Qg of the generator 5 interfere, and can suppress the suppression effect of a voltage fluctuation.

  That is, the reactive power compensation system 7A according to the present embodiment performs the reactive power compensation operation in cooperation with the generator 5. Thus, in this embodiment, even when the load 6 increases rapidly, the generator reactive power Qg and the SVC reactive power Qc are suppressed from canceling each other, and the system voltage (the voltage Vs of the bus system 4) is reduced. The amount of fluctuation can be reduced, and the time until the system voltage returns to the specified value can be shortened. Thereby, in a present Example, the local system | strain 3 can be stabilized and reliability can be improved.

  A second embodiment will be described with reference to FIGS. In the following embodiments including the present embodiment, differences from the first embodiment will be mainly described. This embodiment is different from the first embodiment in that a control device 71B including an interference determination unit 712 is used instead of the control device 71A.

  FIG. 3 is a block diagram showing the configuration of the reactive power compensation system 7B according to this embodiment. The control device 71B is common to the control device 71A of the first embodiment in that it includes an electrical quantity calculation unit 711 and an output signal generation unit 713, but in this embodiment, an interference determination unit 712 is newly provided. It has been.

  The interference determination unit 712 includes a case where the bus voltage Vs is negative, the voltage fluctuation amount ΔVs is positive, and the generator reactive power Qg is positive, and the bus voltage Vs is positive, the voltage fluctuation amount ΔVs is negative, and the generator reactive power Qg is negative. In this case, a correction signal CIF for avoiding interference with the generator 5 is output.

  FIG. 4 is an example of a waveform diagram when the reactive power compensation system 7B of the present embodiment is used. As shown in FIG. 4A, it is assumed that the load current iL of the load facility 6 rapidly increases in a step shape at time t1. When the load current iL increases rapidly, the local system 3 becomes insufficient in power supply, so that the voltage Vs of the bus system decreases from the specified value after t1 as shown in FIG. 4B.

  Since the generator voltage Vg also decreases in conjunction with the decrease in the bus voltage Vs, the reactive power Qg of the generator 5 increases as shown in FIG. As the bus voltage Vs decreases, the generator reactive power Qg continues to increase, and the decrease in the bus voltage Vs stops at time t2.

  On the other hand, the SVC 70 calculates the voltage fluctuation amount ΔVs of the bus system 4 shown in FIG. 4D by the electric quantity calculation unit 711 of the control device 71B, and the output signal generation unit 713 responds to the voltage fluctuation amount ΔVs. An output command Csvc is generated. As shown in FIG. 4 (e), since the voltage fluctuation amount ΔVs is negative between time t1 and time t2, the SVC 70 releases reactive power Qc.

  After time t2, as shown in FIG. 4B, the bus voltage Vs starts to increase and returns to the specified value at time t5. In accordance with this, the generator reactive power Qg also decreases. At this time, since the bus voltage Vs is negative, the voltage fluctuation amount ΔVs is positive, and the generator reactive power Qg is positive, the interference determination unit 712 outputs the correction signal CIF.

  When receiving the correction signal CIF, the output signal generation unit 713 generates the output signal Csvc so that the SVC 70 does not absorb the generator reactive power Qg. Therefore, between time t1 and time t2, voltage fluctuation amount ΔVs is positive, but SVC 70 does not absorb reactive power. That is, the SVC 70 does not interfere with the generator 5 that emits the reactive power Qg.

  As described above, this embodiment also has the same operational effects as the first embodiment. In this embodiment, the timing at which the operation of the generator 5 interferes with the operation of the SVC 70 is detected, and the correction signal CIF is output to the output signal generation unit 713 at that timing, thereby suppressing the absorption of reactive power by the SVC 70. . Therefore, according to the present embodiment, the SVC 70 can be operated efficiently.

  A third embodiment will be described with reference to FIG. The reactive power compensation system 7C of the present embodiment differs from that of the first embodiment in that the connection point of the SVC 70 is changed from a bus system 4 to a line (interconnection line) connecting the bus system 4 and the generator 5. .

  FIG. 5 is a block diagram of a reactive power compensation system 7C according to this embodiment. A connection line L <b> 1 for the SVC 7 to output reactive power Qc is connected to the bus line system 4 and the connection line L <b> 2 of the generator 5.

  Thereby, according to the present embodiment, since the SVC 70 is connected to the generator 5 without going through the bus system 4, the effect of suppressing the voltage fluctuation in the vicinity of the generator 5 and the current component flowing back to the generator 5 are obtained. This can improve the compensation effect. This embodiment can be combined with either the first embodiment or the second embodiment.

  A fourth embodiment will be described with reference to FIG. In the fourth embodiment, several configuration examples of the SVC 70 will be described. Each type of SVC described in the present embodiment is applicable to any of the first to third embodiments.

  A first type SVC 70-1 shown in FIG. 6A can be configured by including a power converter 701 and a DC charging unit 703. As the DC charging unit 703, a DC power source such as a storage battery can be used.

  A second type of SVC 70-2 shown in FIG. 6B includes a power converter 701, an inverse converter 702, a capacitor 704 that connects the power converter 701 and the inverse converter 702, and a DC charging unit 703. And an AC power source 705 for supplying AC power.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. The above-described embodiments are illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to delete a part of the configuration of each embodiment, or to add or replace another configuration. In addition, the control lines and information lines shown in the figure are those that are considered necessary for the explanation, and not all the control lines and information lines that are necessary on the product are shown. Actually, it may be considered that almost all the components are connected to each other.

  Moreover, each component of the present invention can be arbitrarily selected, and an invention having a selected configuration is also included in the present invention. Further, the configurations described in the claims can be combined with combinations other than those specified in the claims.

  1: host system, 2: interconnection line, 3: local system, 4: bus system, 5: generator, 6: load equipment, 7A, 7B, 7C: reactive power compensation system, 10, 11: voltage detector, 12, 13: Current detector: 50: Automatic voltage regulator, 70: Static reactive power compensator, 711: Electric quantity calculation unit, 712: Interference determination unit, 713: Output signal generation unit

Claims (7)

A reactive power compensation system that adjusts reactive power of a system having a generator by a static reactive power compensator,
Various electric quantity calculation units for calculating the voltage fluctuation amount of the system and the first reactive power output by the generator;
The output of the static reactive power compensator is based on the voltage fluctuation amount calculated by the electrical quantity calculator, the first reactive power, the voltage of the system, and the output current of the static reactive power compensator. An output signal generator for generating an output signal for controlling the second reactive power to be
With
The output signal generation unit generates the output signal so as to suppress interference between the first reactive power and the second reactive power.
Reactive power compensation system. The output signal generation unit generates the output signal so that the sign of the first reactive power and the sign of the second reactive power are not reversed.
The reactive power compensation system according to claim 1. An interference determination unit for determining whether the first reactive power and the second reactive power interfere based on the voltage of the system, the voltage fluctuation amount, and the first reactive power;
The output signal generation unit stops the output of the second reactive power when it is determined by the interference determination unit to interfere;
The reactive power compensation system according to claim 1. The static reactive power compensator is connected on a line connecting the system and the generator,
The reactive power compensation system according to any one of claims 1 to 3. A reactive power compensation method for adjusting reactive power of a system having a generator using a static reactive power compensator,
Calculate the voltage fluctuation amount of the system and the first reactive power output from the generator,
Based on the voltage fluctuation amount, the first reactive power, the system voltage, and the output current of the static reactive power compensator, the first reactive power and the second reactive power output from the static reactive power compensator Generating an output signal for controlling the static reactive power compensator so as to suppress interference with power;
Reactive power compensation method. The output signal is generated so that the sign of the first reactive power and the sign of the second reactive power are not reversed.
The reactive power compensation method according to claim 5. The output of the output signal is stopped when it is determined that the first reactive power and the second reactive power interfere with each other.
The reactive power compensation method according to claim 5.

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