JP6070059B2 - Reactive power compensator control method and control apparatus - Google Patents

Description

  The present invention relates to a reactive power compensator connected to an electric power system in order to suppress voltage flicker generated by reactive power of the load in an electric power system in which an electric furnace having an electrode that is controlled to move up and down according to the furnace state exists as a load. The present invention relates to a control method and a control device for a reactive power compensator for controlling the power.

  In an electric power system in which an electric furnace having electrodes that are controlled to move up and down according to the furnace state, a so-called arc furnace exists as a load, a reactive power compensator is installed in order to suppress voltage flicker generated by the reactive power of the load. .

  FIG. 2 shows an example of this type of reactive power compensator. In FIG. 2, a reactive power compensator 1 is connected in parallel to an arc furnace load 4 that is connected to a power system 2 via a system impedance 3. The reactive power compensation device 1 includes a thyristor 5, a reactor 6, a capacitor 7, a transformer 8, a current transformer 9, and a control device 13. As an operation of the reactive power compensator 1, the reactive power generated by the load 4 is compensated to suppress voltage flicker. The reactive power compensator is controlled so that Qt = Qf where the reactive power Qf generated by the load 4, the reactive power of the reactive power compensator 1 is Qt, and the reactive power of the system is Qs (= Qf−Qt). Thus, the reactive power Qs of the system becomes 0, voltage fluctuation of the system voltage can be suppressed, and voltage flicker can be suppressed.

  In order to control the reactive power compensator according to the reactive power of the load, the reactive power of the load is detected by separating it into a reactive power component that changes sharply and a reactive power component that changes relatively slowly. Control devices that command reactive power to be compensated based on components are known (see, for example, Patent Document 1). This known control device is shown in FIG. The control device 13 of FIG. 3 is used as the control device 13 of the reactive power compensator 1 of FIG. 2, and therefore the transformer 8 and the current transformer 9 in FIG. 3 correspond to those of FIG. The transformer 8 detects the system voltage Vs, and the current transformer 9 detects the load current If. The control device 13 includes reactive power detection circuits 10 and 11, a subtractor 14, a surplus capacity calculator 15, and a firing angle control circuit 12.

  Using the detected system voltage Vs and the load current If, the reactive power detection circuit 10 calculates the reactive power Q1 of the load 4, and the reactive power detection circuit 11 calculates the reactive power Q2 of the load 4 that changes relatively slowly. To do. Accordingly, the subtractor 14 subtracts the reactive power Q2 calculated by the reactive power calculation circuit 11 from the reactive power Q1 of the load 4 calculated by the reactive power detection circuit 10 to thereby reduce the steepness of the load 4. The reactive power component ΔQ (Q1−Q2) that fluctuates in the range can be obtained. As a result, the reactive power Q1 of the load 4 includes a reactive power component ΔQ that changes sharply and a reactive power component Q2 that changes relatively slowly, and the reactive power Q1 of the load changes reactively. It can be said that the power component ΔQ and the reactive power component Q2 that changes relatively slowly are detected separately.

  Here, in compensating reactive power, there are two methods: a method of compensating reactive power Q1 (= ΔQ + Q2) of the load 4 and a method of compensating reactive power ΔQ of the load 4 that varies sharply. When flicker is suppressed, reactive power ΔQ that fluctuates rapidly may be compensated. However, since the reactive power Q2 that changes relatively slowly remains, the power factor after compensation does not improve. Further, when the reactive power Q1 of the load 4 is compensated, the power factor is improved, but the compensation capacity of the reactive power compensator 1 is not sufficient to suppress flicker because there is a limit in terms of economical design. . For this reason, the prior art is a method in which flicker is suppressed by compensating reactive power that fluctuates rapidly, and if there is a surplus power, compensation is performed up to power factor.

  For this purpose, a surplus capacity calculation circuit 15 is provided as shown in FIG. The surplus capacity calculation circuit 15 calculates the surplus capacity of the reactive power compensator 1 using the calculation outputs of both the reactive power detectors 10 and 11, and the ineffective capacity fluctuating relatively slowly within the limits of the calculated surplus capacity. Part or all of the power component Q2 is input to the adder 16 as additional compensation. The surplus capacity calculation circuit 15 calculates a surplus capacity value of the reactive power compensator 1 when only the reactive power component ΔQ that varies sharply is compensated, and relatively slowly varies so as not to exceed the surplus capacity value. The reactive power component Q2 can be configured to be limited and output, but for a specific configuration example, refer to Patent Document 1 cited above.

  The adder 16 adds the additional compensation calculated by the surplus capacity calculation circuit 15 to the reactive power component ΔQ that fluctuates rapidly, thereby obtaining a reactive power command value to be compensated. Based on this command value, the firing angle control circuit 12 calculates a firing angle command α, and the thyristor 5 of the reactive power compensator 1 is controlled to fire according to the firing angle command α. For example, when the additional compensation calculated by the surplus capacity calculation circuit 15 is zero, that is, when there is no surplus power, only the reactive power component ΔQ that varies steeply is compensated. Not only the power component ΔQ but also part or all of the reactive power component Q2 that changes relatively slowly is compensated according to the additional compensation calculated by the capacity calculation circuit 15.

  On the other hand, the load 4 shown in FIG. 2 shows an electric furnace as equipment for melting and recycling scrap iron or the like by an arc, and an example of this electric furnace is shown in FIG. 4 includes a current transformer 32, a furnace transformer 31, an electrode 33, a furnace body 34, a current transformer 17, a transformer 18, an electrode lifting device 30 that lifts and lowers the electrode 33, and an electrode lifting device 30. It is comprised by the electrode raising / lowering control apparatus 35 which supplies the electric power required for the speed control of the electrode 33 to the electric motor to comprise. The electrode lift control device 35 includes an arc state calculation circuit 19, a rectifier circuit 20, comparison circuits 21 and 23, setting devices 22 and 24, a timer 25, a flip-flop 26, a switching device 27, a setting device 28, and a lifting control circuit 29. Has been.

  The arc state calculation circuit 19 calculates an impedance from the arc voltage detected by the transformer 18 and the arc current detected by the current transformer 17, and when the impedance becomes smaller than a set value, the speed at which the electrode 33 is raised. On the contrary, when the impedance becomes larger than the set value, a speed command value for lowering the electrode 33 is output.

  The current flowing through the arc furnace detected by the current transformer 32 is rectified by the rectifier circuit 20, and the output value of the rectifier circuit 20 is guided to the comparison circuits 21 and 23. The comparison circuit 21 operates when the output value of the rectifier circuit 20 exceeds an upper limit value (for example, about 110%) set by the setting device 22, and the comparison circuit 23 operates when the output value of the rectification circuit 20 is set by the setting device 24. It operates when it is below the lower limit value (for example, about 80%) set in. When the comparison circuit 21 is operated, the timer 25 is started, and the timer 25 is operated when a period during which the comparison circuit 21 is operated becomes a predetermined time (for example, about 3 seconds) or more. The flip-flop 26 is set when the timer 25 operates, and is reset when the comparison circuit 23 operates.

  The switch 27 selects and outputs the speed command value set by the setting device 28 when the flip-flop 26 is in the set state, and the speed command value calculated by the arc state calculation circuit 19 when the flip-flop 26 is in the reset state. Select to output. In the setting device 28, a predetermined pulling speed command value (maximum value) of the electrode 33 is set. The raising / lowering control circuit 29 controls the raising / lowering of the electrode 33 via the electrode raising / lowering device 30 based on the speed command value output from the switch 27. Accordingly, when the flip-flop 26 is in the set state, the electrode 33 is rapidly raised based on a rapid increase command based on the pulling speed command value (maximum value) of the electrode 33. As a result, for example, in an arc furnace, the duration of overcurrent caused by a phenomenon in which scrap comes into contact with the electrode 33 (collapse phenomenon) is minimized, and a circuit breaker for a furnace (not shown) is prevented from tripping. Here, in general, it is said that a landslide phenomenon frequently occurs during a period of melting the scrap, and flicker occurs frequently during this period.

  The above-described conventional technology has a compensation mode for compensating for the rapidly varying reactive power of the load 4 and compensating for the reactive power of the load 4 in order to compensate for flicker and power factor. However, the switching is performed according to the remaining capacity of the device from the reactive power of the load 4. However, in this case, it takes time to calculate the remaining capacity of the device, etc., and when the reactive power due to steep fluctuations should be compensated for, switching is delayed, so that optimal compensation cannot be performed and the compensation performance is degraded. There is a concern about letting it happen.

JP 2005-080368 A

  The problem of the present invention is that it takes time to calculate the device remaining capacity, etc., and at the point of time when the reactive power of the steep fluctuation should be compensated, the switching is delayed, so that the optimum compensation cannot be performed and the compensation performance is reduced. An object of the present invention is to provide a control method and a control device for a reactive power compensator that solves the problem in the prior art that it is reduced.

  The problem is solved by the reactive power compensator control method according to claim 1 with respect to the method invention, and is solved by the reactive power compensator control device according to claim 4 with respect to the device invention. Preferred embodiments or developments relating to the method invention and the device invention are described in the respective dependent claims.

  According to the present invention, in an electric furnace having electrodes that are controlled to move up and down according to the furnace state, a landslide phenomenon frequently occurs during the period of melting the scrap, and flickering frequently occurs during this period. Paying attention to the fact that the electrode is frequently commanded at a higher speed than usual, the fact that the speed command value for the electrode raising / lowering control of the electric furnace exceeds the predetermined limit value, as a sign of flicker occurrence Starting from the recognition that it can be captured, immediately compensate for the reactive power component that fluctuates relatively slowly in such a case, and compensate so that only the reactive power that fluctuates sharply greatly is compensated. If the reactive power to be switched is switched to the technical idea, it is possible to guarantee the power factor improvement as much as possible without sacrificing flicker suppression and realize optimal compensation. Those were.

  Therefore, the control method according to the present invention is connected to the electric power system in order to suppress voltage flicker generated by reactive power of the load in the electric power system in which an electric furnace having an electrode that is controlled to move up and down according to the furnace state exists as a load. In the control method for controlling the reactive power compensator, the reactive power of the load is detected by separating it into a reactive power component that fluctuates rapidly and a reactive power component that fluctuates relatively slowly. Compensating including not only the component but also all or part of the reactive power component that fluctuates relatively slowly, when the speed command value for the electrode lifting control of the electric furnace exceeds a predetermined limit value, The reactive power to be compensated is switched so as to compensate only for the reactive power component that fluctuates sharply for a certain period of time.

  The control method according to the present invention implements a case where not all but a part of the reactive power component that changes relatively slowly is always compensated at all times other than a fixed time for compensating only the reactive power component that changes sharply. Including as a form. However, in this case, in general, the capacity of the reactive power compensator must be designed large. For economical design of the reactive power compensator, it is preferable to use a conventional control method in which reactive power components that change relatively slowly are not always all, but can be varied according to the remaining capacity value each time. Therefore, according to the embodiment of the present invention, the surplus capacity value of the reactive power compensator when only the reactive power component that changes sharply is compensated is calculated. Compensation should be made within the limits of the calculated surplus capacity value. In this case, switching to compensation of only the reactive power component that changes sharply can be easily performed by forcibly switching the remaining capacity value to zero.

Control apparatus according to the present invention, in order to suppress the voltage flicker caused by reactive power of the load in a power system electric furnace having an electrode for elevation control in accordance with a furnace condition exists as a load was connected to the electric power system In the control device that controls the reactive power compensator,
Reactive power detection means for detecting the reactive power component of the load by separating it into a reactive power component that fluctuates sharply and a reactive power component that fluctuates relatively slowly;
Comparison means for receiving a speed command value calculated for electrode elevation control in the electrode elevation control device of the electric furnace and comparing it with a preset limit value;
A timing means for generating a timed signal that lasts for a certain time in response to an output signal generated by the comparing means when the speed command value exceeds a limit value;
Normally, reactive power including all or part of reactive power components that fluctuate slowly as well as reactive power components that fluctuate steeply is selected as a compensation reactive power command value, and the timing means generates a time signal. Switching means for selecting only the reactive power component that varies sharply as the compensation reactive power command value,
Control means for generating a control signal for the reactive power compensator based on the compensation reactive power command value selected by the switching means.

Control apparatus according to the present invention, according to one embodiment, further, a calculator for calculating the surplus capacity value of the reactive power compensator in the case of compensating for only the reactive power component varying rapidly, the margin capacitance value A surplus capacity calculation means comprising an output limiting unit that limits and outputs a reactive power component that fluctuates relatively slowly so as not to exceed,
Adding means for adding the output of the limiting unit to the reactive power component that fluctuates sharply and outputting as a compensated reactive power command value to be selected by the switching means at all times.

  According to the control method according to the present invention, compensation is made including all or part of the reactive power component that fluctuates relatively slowly as well as the reactive power component that fluctuates abruptly. Cause the flicker by switching the reactive power to be compensated so as to compensate only for the reactive power component that fluctuates sharply for a certain period of time when the speed command value for this exceeds a predetermined limit value. It is possible to immediately shift to an operation mode in which the maximum capability can be exhibited for compensation for the reactive power component of the load that fluctuates rapidly. Therefore, while performing reactive power compensation operation including power factor improvement at all times, it shifts to the optimum reactive power compensation operation for flicker suppression without delay in the important period for flicker suppression, and sufficient compensation Performance can be demonstrated. Furthermore, it can be used in combination with a conventional control method that suppresses flicker while improving the power factor within the limit by obtaining the remaining capacity in consideration of the capacity limit of the reactive power compensator. It is possible to solve the problem of response delay caused by the capacity calculation and to further improve the compensation performance.

FIG. 1 is a block diagram showing an embodiment of a control device for a reactive power compensator according to the present invention. FIG. 2 is a block diagram illustrating a schematic configuration example of the reactive power control apparatus. FIG. 3 is a block diagram showing a conventional embodiment of a control device for a reactive power compensator. FIG. 4 is a block diagram showing a schematic configuration example of an electric furnace provided with an electrode lifting control device.

  FIG. 1 shows an embodiment of a control device for a reactive power compensator according to the present invention. Components corresponding to each other in FIGS. 1 to 4 are denoted by the same reference numerals. In FIG. 1, reference numeral 1 denotes a reactive power compensator, the main circuit of which is composed of a thyristor 5, a reactor 6 and a capacitor 7 as shown in FIG. 2. In a power system 2 having a system inductance 3, a load 4 Are connected in parallel. In FIG. 1, the load 4 is shown as a load 4 having the same configuration as that of FIG. 4.

  The load 4 is an arc furnace composed of a furnace body 34, an electrode 33, a furnace transformer 31, an electrode lifting device 30, an electrode lifting control device 35, a current transformer 32, a current transformer 17 and a transformer 18. On the input side of the electrode lifting / lowering control device 35, a rectifier circuit 20 that rectifies the load current detected by the current transformer 32 and converts it into a DC signal is provided on the one hand, and the current transformer 17 and the transformer 18 on the other hand. An arc state calculation circuit 19 is provided which calculates a speed command value for electrode lifting control in accordance with the impedance obtained from the arc current and arc voltage detected in step (b). The arc state calculation circuit 19 outputs a speed command value for raising the electrode 33 when the obtained impedance becomes smaller than the set value, and conversely, a speed command for lowering the electrode 33 when the impedance becomes larger than the set value. Output the value. The output of the arc state calculation circuit 19 is input to the elevation control circuit 29 as a speed command value Nd via the switch 27. The lift control circuit 29 supplies necessary electric power to the electric motor of the electrode lift device 30 according to the speed command value Nd.

  When an overcurrent occurs in the arc furnace, the electrode 33 is rapidly raised by a predetermined pulling speed command value (maximum value) in order to minimize the duration of the overcurrent. For this purpose, a speed command value (maximum value) for rapid rise of the electrode 33 is set in the setting device 28, and the speed command value Nd input to the elevation control circuit 29 is changed by the switch 27. Thus, the speed command value calculated by the arc state calculation circuit 19 can be switched to the speed command value set by the setting device 28.

  In order to determine the overcurrent, the load current detection value converted into a DC signal by the current transformer 32 and the rectifier circuit 20 is the upper limit value (for example, 110) set by the setting unit 22 in the comparators 21 and 23. %) And a lower limit value set by the setting device 24 (for example, about 80%). The comparator 21 operates when the load current detection value exceeds the upper limit value, and starts the timer 25. The timer 25 has a period during which the comparator 21 is operating for a predetermined time period (for example, about 3 seconds) or more. And the flip-flop 26 is set. The comparator 21 operates when the load current detection value falls below the lower limit value and resets the flip-flop 26. The switch 27 selects the speed command value calculated by the arc state calculation circuit 19 in the reset state of the flip-flop 26 as the speed command value Nd to be input to the elevation control circuit 29, and sets it in the set state of the flip-flop 26. The speed command value (maximum value) for rapid electrode elevation set by the device 28 is selected. As a result, for example, in an arc furnace, the duration of overcurrent caused by a phenomenon in which scrap comes into contact with the electrode 33 (collapse phenomenon) is minimized, and a circuit breaker for a furnace (not shown) is prevented from tripping.

  The control device 13 of the reactive power compensator 1 includes, as reactive power detection means, in addition to the transformer 8 that detects the system voltage Vs and the current transformer 9 that detects the load current If, two reactive power detection circuits 10 and 10 11 and a subtractor 14. From the detected voltage Vs and the load current If, one reactive power detection circuit 10 detects the reactive power Q1 of the load 4, and the other reactive power detection circuit 11 detects the reactive power component Q2 of the load 4 that changes relatively slowly. To detect.

  The reactive power component Q2 that changes relatively slowly is appropriately selected according to the specifications of the apparatus, and is a reactive power that fluctuates below a frequency that hardly affects the flicker of the power supply voltage lower than the power supply frequency, for example, a frequency that is 1 Hz or less. Although it can be set as an electric power component, it is not restricted to this.

  The subtractor 14 calculates the reactive power component ΔQ (= Q1−Q2) of the load 4 that changes sharply by subtracting the reactive power component Q2 of the load 4 that changes relatively slowly from the reactive power Q1 of the load 4. To do. Accordingly, the reactive power Q1 of the load 4 detected by the reactive power detection circuit 10 includes a reactive power component ΔQ that changes sharply in the load 4 and a reactive power component Q2 that changes relatively slowly in the load 4 ( Q1 = ΔQ + Q2). Therefore, the reactive power detection circuits 10 and 11 and the subtractor 14 change the reactive power Q1 of the load 4 into a reactive power component ΔQ that changes sharply in the load 4 and a reactive power component Q2 that changes relatively slowly in the load 4. Reactive power detection means for detecting separately.

  The control device 13 includes a firing angle control circuit 12, a comparator 38, and a timer 36 in addition to the reactive power detection means. The switch 37 selects the reactive power to be compensated from the reactive power detected by the reactive power detection means or its component, that is, the compensated reactive power command value. The switch 37 selects the reactive power Q1 (= ΔQ + Q2) of the load detected by the reactive power detection circuit 10 at all times, and inputs it to the firing angle control circuit 12 as a compensated reactive power command value. The firing angle control circuit 12 converts the input compensation reactive power command value into a firing angle command α, and controls the thyristor 5 of the reactive power compensation device 1.

In accordance with the present invention, the comparator 38 receives a speed command value Nd for electrode elevation control calculated in the electrode elevation control device 35 described above. The comparator 38 compares the speed command value Nd with the limit value set in the internal setting device, and starts the timer 36 when the magnitude of the speed command value exceeds the limit value. Generate an output signal. The activated timer 36 generates a time signal that operates for a predetermined time. Even if the speed command value Nd falls below the limit value on the way, the switch 37 selects the reactive power component ΔQ that changes sharply from the subtractor 14 while the time limit signal is generated. This is input to the firing angle control circuit 12 as a compensation reactive power command value.
Therefore, the control device 13 detects the reactive power component Q1 of the load by separating it into the reactive power component ΔQ that changes sharply and the reactive power component Q2 that changes relatively slowly, and normally the reactive power component Q1 (= ΔQ + Q2) is compensated, and when the electrode speed command value Nd calculated for the electrode raising / lowering control of the electric furnace exceeds a preset limit value, the reactive power component that fluctuates sharply for a certain time The reactive power to be compensated (compensated reactive power command value) is switched so as to compensate only for the above. As a result, the power factor can be improved at the same time as the flicker suppression at all times, but the system can be shifted to a posture that enables the best compensation for flicker suppression without delay when necessary. In this way, flicker can be effectively compensated by compensating only the reactive power component ΔQ that fluctuates sharply during a period in which flicker occurs frequently.

  The control device 13 in FIG. 1 always compensates not all but part of the reactive power component Q2 that changes relatively slowly at all times other than a fixed time in which only the reactive power component ΔQ that changes sharply is compensated. However, in this case, generally, the reactive power compensator must be designed with a large capacity. For the economic design of reactive power compensators, the reactive power components that change relatively slowly are not always subject to compensation, but are limited in part depending on the capacity value of each time. It is preferable to use it together with a conventional control method. Thus, according to the embodiment of the present invention, the remaining capacity value of the reactive power compensator when only the reactive power component that changes sharply is compensated is calculated, and the reactive power component that constantly changes relatively slowly is calculated. Compensation should be made within the limits of the remaining capacity value. Switching to compensation for only the reactive power component that changes sharply can be performed by forcibly switching the remaining capacity value to zero.

  As described above, the surplus capacity calculation circuit 15 of the conventional control device 13 (FIG. 3) includes a calculation unit that calculates the surplus capacity value of the apparatus 1 when only the reactive power component ΔQ that changes sharply is compensated, A limiting unit that limits and outputs the reactive power component Q2 that changes relatively slowly so as not to exceed the remaining capacity value can be configured. Therefore, in the modified example of the control device 13 according to the present invention, an adding means for adding the rapidly varying reactive power component ΔQ from the subtractor 14 and the output from the limiting unit is provided, and the output of the adding means is compensated invalid. By inputting the command value to the firing angle control circuit 12 as a power command value, not only the reactive power component ΔQ that changes abruptly but also part or all of the reactive power component Q2 that changes relatively slowly can be compensated. It is possible. In this case, switching to compensation for only the reactive power component ΔQ that varies sharply can be easily performed by forcibly switching the output of the limiting unit to zero by a switch responding to the time limit signal of the timer 36. It is.

1 Reactive Power Compensator 2 Power System 3 System Impedance 4 Load 5 Thyristor 6 Reactor 7 Capacitor 8 Transformer 9 Current Transformer 10 Reactive Power Detection Circuit 11 Reactive Power Detection Circuit 12 Firing Angle Control Circuit 13 Controller 14 Subtractor 15 Surplus Power Capacitance calculator 16 Adder 17 Current transformer 18 Transformer 19 Arc state calculator 20 Rectifier circuit 21 Comparator 22 Setter 23 Comparator 24 Setter 25 Timer 26 Flip-flop 27 Switch 28 Setter 29 Lift control circuit 30 Electrode Lifting device 31 Transformer for furnace 32 Current transformer 33 Electrode 34 Furnace body 35 Electrode lifting control device 36 Timer 37 Switch 38 Comparator

Claims (6)

In an electric power system in which an electric furnace having electrodes that are controlled to move up and down according to the furnace state exists as a load, the reactive power compensator connected to the electric power system is controlled in order to suppress voltage flicker generated by the reactive power of the load. In the control method,
The reactive power of the load is detected by separating it into a reactive power component that changes sharply and a reactive power component that changes relatively slowly,
Always compensate for all or part of the reactive power component that fluctuates slowly as well as the reactive power component that fluctuates abruptly. Control of reactive power compensator characterized by switching reactive power to be compensated so as to compensate only for reactive power components that fluctuate sharply for a certain period of time when a value exceeds a preset limit value Method.   The remaining capacity value of the reactive power compensator is calculated when only the reactive power component that changes sharply is compensated. The compensation of the reactive power component that changes relatively slowly at any time is within the limits of the calculated remaining capacity value. The method of controlling a reactive power compensator according to claim 1, wherein compensation is performed.   3. The reactive power compensator control method according to claim 2, wherein switching to compensation of only the reactive power component that changes sharply is performed by forcibly switching the remaining capacity value to zero. Reactive power connected to the power system in order to suppress voltage flicker generated by the reactive power of the load (4) in the power system where the electric furnace having electrodes controlled to be raised and lowered according to the furnace state exists as the load (4) In the control device for controlling the compensation device (1),
Reactive power detection means (10, 11, 14) for detecting reactive power (Q1) of the load (4) by separating it into a reactive power component (ΔQ) that changes sharply and a reactive power component (Q2) that changes relatively slowly. )When,
Comparison means (38) for receiving a speed command value (Nd) calculated for electrode elevation control in the electrode elevation control device (35) of the electric furnace and comparing it with a preset limit value;
Timing means (36) for generating a timed signal that lasts for a certain time in response to an output signal generated by the comparison means (38) when the speed command value (Nd) exceeds a limit value;
Normally, reactive power including all or part of reactive power component (Q2) that fluctuates relatively slowly as well as reactive power component (ΔQ) that varies sharply is selected as a compensation reactive power command value, and the time limit means (36) While the time signal is generated, the switching means (37) for selecting only the reactive power component that changes sharply as the compensation reactive power command value;
Reactive power compensation comprising control means (12) for generating a control signal for the reactive power compensator (1) based on the compensation reactive power command value selected by the switching means (37) Control device for the device. An arithmetic unit for calculating the surplus capacity value of the reactive power compensator (1) when only the steeply varying reactive power component (ΔQ) is compensated, and the reactive power that varies relatively slowly so as not to exceed the surplus capacity value A surplus capacity calculation means (15) having a limiting unit for limiting and outputting the component (Q2);
Adding means (16) for adding the output of the limiting unit to the reactive power component (ΔQ) that changes sharply and outputting the compensation reactive power command value to be selected by the switching means (37) at all times; The control device for a reactive power compensator according to claim 4. The switching means (37) is configured to forcibly switch the output of the limiting section guided to the adding means (16) to zero in response to the time limit signal. 5. A control device for a reactive power compensator according to 5.

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