Reactive power compensation device

Abstract

To provide a reactive power compensation device capable of suppressing influences, caused by a voltage regulation device which determines a transformer station direction, upon the transformer station direction determination even in a case where the voltage regulation device is connected to a distribution line together with a voltage fluctuation compensation device.SOLUTION: A reactive power compensation device (SVC) 1 is connected to an interconnection point (SVC power reception point) 101 of a distribution line 100 where a voltage regulation device (distributed power supply adaptable SVR) 2 is disposed which performs a transformer station direction determination about which of a primary side and a secondary side a transformer station is connected to. The reactive power compensation device (SVC) 1 comprises a control section which controls output of reactive power corresponding to a voltage fluctuation in the distribution line. The control section performs influence suppression processing for suppressing influences, caused by the voltage regulation device, upon the transformer station direction determination when outputting reactive power.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reactive power compensation device. [Background technology]

[0002] Regarding a voltage fluctuation compensation device for a busbar on the power supply side in a power distribution system that supplies power from a power source to a load, a voltage fluctuation compensation device is known that can reduce the capacity of a reactive power compensation device and respond to not only fluctuations on the load side but also load fluctuations on the power source side (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-317523 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the voltage fluctuation compensation device disclosed in Patent Document 1 does not take into consideration the fact that when a voltage adjustment device that performs substation direction determination is connected to a distribution line together with the voltage fluctuation compensation device, the output of reactive power corresponding to voltage fluctuations in the distribution line is controlled so as to suppress the influence on the substation direction determination by the voltage adjustment device.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a reactive power compensation device that can suppress the influence of a voltage regulating device that performs substation direction determination on the substation direction determination, even when the voltage regulating device is connected to a distribution line together with a voltage fluctuation compensation device. [Means for solving the problem]

[0006] A reactive power compensation device according to one embodiment of the present disclosure is a reactive power compensation device connected to an interconnection point of a distribution line where a voltage regulating device that performs substation direction determination as to whether the substation is connected to the primary side or secondary side is located, and is equipped with a control unit that controls the output of reactive power in response to voltage fluctuations in the distribution line, and when outputting reactive power, the control unit performs an effect suppression process that suppresses the effect on the substation direction determination by the voltage regulating device.

[0007] In this embodiment, a voltage regulator and a reactive power compensator are arranged (installed in the same system) on a distribution line extending from a substation. The voltage regulator is, for example, a distributed power source compatible SVR (Step Voltage Regulator), and performs substation direction determination to determine whether the substation is located on the primary side or the secondary side. When performing the substation direction determination, the voltage regulator compares, for example, the amount of change in the primary side voltage and the amount of change in the secondary side voltage at the time of tap switching (before and after tap switching), and determines that the side with the smaller amount of change is the side to which the substation is connected (substation direction). The voltage regulator performs tap switching in response to a relatively gradual voltage fluctuation in the voltage of the distribution line (distribution line voltage), and performs tap control so that the voltage of the distribution line on the load side approaches the target voltage (so that it falls within the dead zone). The var compensator is, for example, a static var compensator (SVC) or a static synchronous compensator (STATCOM), and is connected to a distribution line via an interconnection point (SVC receiving point). The var compensator may be connected to a distribution line on the secondary side of a voltage regulator. The var compensator automatically adjusts (performs voltage compensation) the distribution line voltage to a target voltage value by outputting reactive power in response to abrupt voltage fluctuations in the voltage (distribution line voltage) of the distribution line (interconnection point). That is, the var compensator outputs reactive power (performs voltage compensation) in response to abrupt voltage fluctuations (larger amount of voltage change per unit time) than the voltage fluctuations that the voltage regulator responds to (switches taps). The reactive power compensator outputs leading reactive power (leading-phase reactive power) when the distribution line voltage is lower than the target voltage value (a voltage increase is required), and outputs lagging reactive power (lagging-phase reactive power) when the distribution line voltage is higher than the target voltage value (a voltage effect is required).When the voltage regulator performs tap switching, the reactive power compensator is expected to output reactive power according to the voltage fluctuation of the distribution line voltage caused by the tap switching and execute voltage compensation, which instantly suppresses the voltage change amount on the secondary side of the voltage regulator (the voltage change amount at the time of tap switching).Therefore, the voltage regulator may not be able to correctly calculate the voltage change amount at the time of tap switching or the change amount of the system impedance (system impedance change amount) using the voltage change amount, and it may become impossible to execute the substation direction determination based on the voltage change amount or the system impedance change amount. In response to this, the control unit of the reactive power compensation device executes an influence suppression process to suppress the influence on the substation direction determination by the voltage regulator when outputting reactive power according to the voltage fluctuation in the distribution line. That is, the control unit of the reactive power compensation device executes the influence suppression process in conjunction with the reactive power output control, thereby improving the determination accuracy of the substation direction determination. By executing such an influence suppression process by the reactive power compensation device, it becomes possible to substantially coordinate and control the reactive power compensation device and the voltage regulator installed in the same system, and the substation direction determination by the voltage regulator can be reliably executed, and the determination accuracy can be guaranteed. That is, even if the reactive power compensation device and the voltage regulator are not interconnected by, for example, a communication line or the like and operate independently, the effectiveness or reliability of the process of the substation direction determination by the voltage regulator can be ensured by executing the influence suppression process by the reactive power compensation device.

[0008] In a reactive power compensation device according to one embodiment of the present disclosure, when performing the influence suppression processing, the control unit acquires a interconnection point voltage value at the interconnection point, derives a compensation voltage value based on the output reactive power and a predetermined system impedance, derives an uncompensated interconnection point voltage value indicating the voltage value at the interconnection point when no voltage compensation is performed based on the acquired interconnection point voltage value and the compensation voltage value, determines whether tap switching of the voltage adjustment device has been performed based on the voltage change amount of the derived uncompensated interconnection point voltage value, and if it is determined that tap switching of the voltage adjustment device has been performed, reduces the output amount of reactive power according to a compensation voltage value equivalent to the voltage fluctuation range due to tap switching of the voltage adjustment device.

[0009] In this aspect, when performing the influence suppression process, the control unit of the reactive power compensator reduces the amount of reactive power output when it is determined that the tap of the voltage regulator has been switched. When reducing the amount of reactive power output, the amount of reduction may be adjusted to a compensation voltage value corresponding to a voltage fluctuation width caused by the tap switching of the voltage regulator. The control unit of the reactive power compensator constantly or periodically acquires a voltage value (interconnection point voltage value) at the interconnection point (a connection point where the reactive power compensator is connected in parallel: SVC receiving point). The control unit of the reactive power compensator further periodically derives a compensation voltage value based on the reactive power amount (Var) currently being output and a system impedance (system impedance from the substation to the interconnection point: R, X) that is set in advance. The control unit is configured with a microcomputer or the like including a storage unit such as a memory, and the system impedance (R, X) is stored in the storage unit. The control unit of the reactive power compensator associates the acquired or derived interconnection point voltage value, reactive power amount, and compensation voltage value with the time of acquisition or derivation, and stores them in the storage unit. The control unit of the reactive power compensation device periodically derives a tie-point voltage value (original tie-point voltage value: uncompensated tie-point voltage value) in the case where voltage compensation is not performed (when voltage compensation is not performed) by subtracting (subtracting) a compensation voltage value that is substantially at the same derivation time point from the tie-point voltage value (measured value at the tie-point) at the current time point, and stores the derived voltage value in the storage unit in association with the derivation time point. The control unit of the reactive power compensation device determines whether or not tap switching of the voltage adjustment device has been performed based on voltage change amounts of a plurality of uncompensated tie-point voltage values ​​derived in a predetermined processing unit time. The control unit of the reactive power compensation device may determine that tap switching has been performed, for example, when the voltage change amount of the uncompensated tie-point voltage value corresponds to a voltage width of one tap (a step voltage for one tap) in the voltage adjustment device. When the control unit of the reactive power compensation device determines that tap switching has been performed, it instantly abandons compensation of reactive power by the voltage fluctuation width caused by the tap switching, that is, it reduces the amount of reactive power output according to the voltage fluctuation width. The amount of reduction in the reactive power amount is not limited to the same amount as the voltage fluctuation width caused by tap switching, and may be, for example, half the voltage fluctuation width.That is, when the control unit of the reactive power compensator determines that tap switching has been performed, the amount of reduction in the reactive power to be output may be any amount between 50% and 100% of the voltage fluctuation width due to the tap switching. In this way, the control unit of the reactive power compensator reduces the amount of reactive power to be output (abandoning the compensation of reactive power corresponding to the voltage fluctuation width due to the tap switching) when the voltage regulator performs tap switching as an influence suppression process, so that the voltage regulator can reliably detect the voltage change at the time of tap switching and reliably execute the substation direction determination based on the detection. When the control unit of the reactive power compensator determines that tap switching has not been performed in the voltage regulator, it continues the output of reactive power corresponding to the voltage fluctuation in the distribution line (normal voltage compensation process) without performing the influence suppression process. As a result, during the period when the tap switching of the voltage regulator is not performed, the reactive power compensator controls the output of reactive power corresponding to the voltage fluctuation in the distribution line and can automatically adjust the distribution line voltage (voltage at the interconnection point) to a set value.

[0010] In a reactive power compensation device according to one embodiment of the present disclosure, the control unit determines that tap switching of the voltage regulator has been performed when the voltage change amount of the derived uncompensated interconnection point voltage value is within a predetermined range based on the voltage width of one tap in the voltage regulator and is below a predetermined threshold value within a predetermined period of time from the time the voltage change amount is detected.

[0011] In this embodiment, when determining that tap switching of the voltage regulator has been performed, the control unit of the reactive power compensation device determines whether or not the voltage change amount of the uncompensated interconnection point voltage value is within a predetermined range based on the voltage width of one tap (step voltage for one tap) in the voltage regulator. The predetermined range indicates, for example, a range of ±10% (for example, from 90V to 110V) based on the voltage width of one tap (step voltage for one tap, for example, 100V). Various values, constants, or parameters required for calculations by the control unit of the reactive power compensation device, such as the predetermined range based on the voltage width of one tap (step voltage for one tap), are stored in the storage unit of the microcomputer constituting the control unit. The control unit of the reactive power compensation device judges that the voltage fluctuation is due to tap switching (determines that tap switching has been performed) when the voltage change amount of the uncompensated interconnection point voltage value is within a predetermined range (corresponding to a step voltage) based on the voltage width of one tap (step voltage for one tap) and there is no significant change in the uncompensated interconnection point voltage value (original interconnection point voltage value) for a predetermined period (output abandonment time) from the detection of the voltage change (time point at which the voltage change amount is detected). No significant change in the uncompensated interconnection point voltage value (original interconnection point voltage value) means that the voltage change amount of the uncompensated interconnection point voltage value is equal to or less than a predetermined threshold value during the predetermined period from the time point at which the voltage change amount is detected. The predetermined period (e.g., 100 nsec to 10 msec) and the threshold value (e.g., ±10%) are stored in the memory unit of the microcomputer constituting the control unit. Compared to the time required for tap switching of the voltage regulator (e.g., 2 seconds), the predetermined period (e.g., 10 msec) used by the control unit of the reactive power compensation device for the judgment process is extremely short. Therefore, the control unit of the reactive power compensation device performs an influence suppression process of reducing the amount of reactive power to be output (abandoning the compensation of reactive power according to the voltage fluctuation width due to tap switching) after a predetermined period (e.g., 10 msec) has elapsed since the detection of the tap switching, which is extremely short compared to the required time (e.g., 2 seconds). As a result, at the moment reactive power compensation is abandoned, the voltage fluctuation due to tap switching for one tap that would have normally occurred in the interconnection point voltage occurs with a time lag (occurs with a delay).By detecting the voltage fluctuation caused by the tap switching that occurs with this time lag (delay), the voltage regulator can correctly determine the substation direction, that is, that the primary side is in the substation direction. If the uncompensated interconnection point voltage value (original interconnection point voltage value) does not change by an amount that can occur in a voltage width of one tap, or if it fluctuates continuously, the control unit of the reactive power compensator determines that tap switching has not occurred (the voltage fluctuation is not a change due to tap switching). In this way, the control unit of the reactive power compensator determines whether or not the voltage regulator has performed tap switching, so that the accuracy of the determination can be improved, and cooperative control between the reactive power compensator and the voltage regulator can be efficiently performed without affecting the substation direction determination by the voltage regulator.

[0012] In a reactive power compensation device according to one embodiment of the present disclosure, when the control unit executes a process of reducing the output amount of reactive power as the influence suppression process, the control unit cancels the process of reducing the output amount of reactive power after a predetermined continuous processing period has elapsed.

[0013] In this embodiment, when the control unit of the reactive power compensator executes a process of reducing the output amount of reactive power, which is an influence suppression process, in response to detection of tap switching of the voltage adjustment device, the control unit cancels the process of reducing the output amount of reactive power after a predetermined continuous processing period has elapsed. The continuous processing period (e.g., 2 seconds) is stored in the storage unit. This allows the control unit of the reactive power compensator to continue outputting reactive power according to voltage fluctuations in the distribution line (normal voltage compensation process) without reducing the output amount of reactive power. Note that, when a process of reducing the output amount of reactive power is executed as the influence suppression process, the cancellation of the process is not limited to being triggered by the elapse of the continuous processing period. The control unit may use a voltage value after a voltage change due to tap switching as a reference voltage value, and thereafter calculate a moving average of a plurality of periodically acquired interconnection point voltage values, and perform control related to voltage compensation (reactive power output control) using the calculated moving average as a reference voltage value.

[0014] In a reactive power compensation device according to one embodiment of the present disclosure, the control unit performs an effect suppression process by setting the upper limit value of the compensation voltage caused by outputting reactive power to a value smaller than the voltage width of one tap in the voltage adjustment device.

[0015] In this embodiment, the control unit of the reactive power compensation device outputs leading or lagging reactive power (leading-phase reactive power or lagging-phase reactive power) to increase or decrease the voltage (connection point voltage value) at the interconnection point (SVC power receiving point) so as to reach a predetermined set value (target voltage value). When outputting the reactive power, the control unit of the reactive power compensation device determines or increases or decreases the amount of reactive power to be output according to the difference between the set value (target voltage value) and the voltage at the interconnection point at the current point in time (interconnection point voltage value). At this time, the control unit of the reactive power compensation device limits the upper limit value of the output amount of reactive power (amount of reactive power to be output) so as to obtain a compensation voltage (absolute value of voltage value that increases or decreases with respect to the current interconnection point voltage value) that is smaller than the voltage width of one tap in the voltage regulator (one tap's worth of step voltage, e.g., 100V). Therefore, even if a voltage fluctuation equivalent to a voltage width of one tap (step voltage of one tap) occurs due to tap switching of the voltage regulator, the control unit of the reactive power compensator does not perform voltage compensation for the entire amount of the voltage fluctuation. As a result, voltage compensation is not performed for the amount exceeding the upper limit, and the amount of voltage not compensated remains as a voltage change on the secondary side. On the primary side, a voltage change (a voltage change less than the voltage width of one tap) occurs due to the compensation voltage up to the upper limit due to voltage compensation by the reactive power compensator. On the other hand, in comparing the magnitude of the voltage change between the primary side and the secondary side, the voltage change of the voltage on the secondary side (load side) (voltage change on the secondary side) remains larger than the voltage change on the primary side due to the influence of the system impedance of the secondary side, which is the load side, so the voltage regulator can normally determine that the substation is on the primary side in the substation direction determination.

[0016] In one embodiment of the reactive power compensation device of the present disclosure, an upper limit value of the compensation voltage caused by outputting reactive power is 20% to 50% of the voltage width of one tap in the voltage adjustment device, and the control unit accepts any value between 20% and 50% of the voltage width of one tap as a setting value, and sets the upper limit value of the compensation voltage to the accepted setting value.

[0017] In this embodiment, the upper limit of the compensation voltage by outputting reactive power is set to 20% to 50% of the voltage width of one tap (e.g., 100V) in the voltage regulator, that is, any value between 20% and 50% (e.g., from 20V to less than 50V). Therefore, for voltage fluctuations of one tap voltage width due to tap switching of the voltage regulator, the reactive power compensator performs voltage compensation by outputting reactive power with any value between 20% and 50% of the voltage fluctuation amount as the upper limit of the compensation voltage. In this case, 50% to less than 80% of the voltage width of one tap remains as a voltage change on the secondary side. On the primary side, a voltage change of 20% to less than 50% of the voltage width of one tap occurs. In this case, a comparison of the magnitude of the voltage change on both sides (primary side and secondary side) can maintain a state in which the voltage change on the secondary side is larger, so that the voltage regulator can normally determine that the substation is on the primary side in the substation direction determination. The control unit of the reactive power compensator receives (acquires) a set value indicating any value between 20% and 50% of the voltage width of one tap via, for example, an input / output IF or the like provided in a microcomputer constituting the control unit, and sets the upper limit value of the compensation voltage by storing the received set value in a storage unit. In other words, the upper limit value of the compensation voltage set by the reactive power compensator is allowed to be changed according to the system in which the reactive power compensator is installed. This improves the availability of the reactive power compensator and efficiently performs cooperative control with the voltage adjustment device.

[0018] In one embodiment of the reactive power compensation device of the present disclosure, when performing the influence suppression processing, the control unit acquires a interconnection point voltage value at the interconnection point, derives a frequency of the interconnection point voltage based on the acquired multiple interconnection point voltage values, and if the derived frequency is lower than the commercial power supply frequency from the substation, performs processing to output reactive power corresponding to the voltage fluctuation at the interconnection point.

[0019] In this aspect, the control unit of the reactive power compensation device constantly or periodically acquires a connection point voltage value at the interconnection point (a connection point where the reactive power compensation device is paralleled: an SVC receiving point) and derives the frequency of the voltage fluctuation at the interconnection point (extracts the frequency component of the interconnection point voltage) by using a plurality of interconnection point voltage values ​​arranged in time series, for example, by using a frequency analysis process or a filter circuit. When extracting the frequency component of the interconnection point voltage, the control unit of the reactive power compensation device may extract the frequency component for one cycle of the voltage fluctuation at the interconnection point. When the derived frequency (fluctuation frequency of the interconnection point voltage) is a relatively low frequency (low frequency) that is lower than the commercial power supply frequency from the substation and is a low frequency that continues to be generated while maintaining a large amplitude, the control unit of the reactive power compensation device performs processing to output reactive power according to the voltage fluctuation at the interconnection point. The relatively low frequency (low frequency) that is less than the commercial power frequency may be, for example, any value (low frequency) of less than half, less than 2 / 3, or less than 3 / 4 of the commercial power frequency, and the voltage regulator may be configured so that the value (low frequency) can be set in a stepwise manner. Therefore, the reactive power compensator can efficiently perform voltage compensation for low-frequency voltage fluctuations that are less than the commercial power frequency from the substation (for example, less than half the commercial power frequency). When the derived frequency (frequency of fluctuation of the interconnection point voltage) exceeds half the commercial power frequency from the substation, the control unit of the reactive power compensator does not perform processing to output reactive power according to the voltage fluctuation at the interconnection point. Since the frequency of the voltage fluctuation when the tap of the voltage regulator is changed exceeds half the commercial power frequency from the substation, the voltage change that occurs only at the timing of the tap change due to the tap change is not suppressed. Therefore, the voltage regulator can reliably detect the voltage change at the time of tap change and can reliably perform the substation direction determination based on the detection.

[0020] In one embodiment of the reactive power compensation device of the present disclosure, a power conditioner having an islanding prevention function is connected to the distribution line, and the control unit performs processing to output reactive power corresponding to voltage fluctuations at the interconnection point when the derived frequency corresponds to a frequency due to reactive power output when the power conditioner performs the islanding prevention function.

[0021] In this embodiment, a power conditioner (PCS) having an islanding prevention function is connected to the power distribution line, that is, a voltage regulator (SVR), a static var compensator (SVC, STATCOM), and the power conditioner (PCS) are installed (connected) in the same system. The power conditioner has an islanding prevention function, and outputs reactive power when performing the islanding prevention function. It is assumed that continuous voltage flicker of low frequency (for example, around 5 Hz) occurs in the system (power distribution line) due to the reactive power output by the islanding prevention function of the power conditioner. In response to this, the control unit of the reactive power compensator performs processing to output reactive power corresponding to the voltage fluctuation at the interconnection point when the derived frequency (frequency of fluctuation of the interconnection point voltage) corresponds to the frequency due to the reactive power output when the power conditioner performs the islanding prevention function. That is, the control unit of the reactive power compensator judges whether the derived frequency (frequency of fluctuation of the interconnection point voltage) is within a predetermined range (e.g., ±10%) based on the frequency (frequency of voltage flicker) due to reactive power output when the power conditioner exerts its islanding prevention function, and performs voltage compensation if it falls within the predetermined range. This allows the reactive power compensator to detect voltage flicker caused by the islanding prevention function of the power conditioner, and when voltage flicker occurs, it can effectively perform voltage compensation for voltage fluctuations caused by the voltage flicker. Effect of the Invention

[0022] Even when a voltage regulating device that performs substation direction determination is connected to a distribution line together with a voltage fluctuation compensation device, a reactive power compensation device can be provided that suppresses the influence of the voltage regulating device on the substation direction determination. [Brief description of the drawings]

[0023] [Figure 1] 1 is a configuration diagram showing a system including a reactive power compensation device according to a first embodiment (tap switching detection). [Diagram 2] 1 is a block diagram showing a configuration example of a reactive power compensation device; [Diagram 3] FIG. 2 is an explanatory diagram showing voltage fluctuations on the primary and secondary sides of a voltage regulator (without effect suppression processing). [Figure 4] FIG. 2 is an explanatory diagram showing voltage fluctuations on the primary and secondary sides of a voltage regulator (with effect suppression processing); [Diagram 5] 10 is a flowchart showing a processing procedure of a control unit. [Figure 6] FIG. 11 is an explanatory diagram showing voltage fluctuations on the primary and secondary sides of a voltage regulator according to the second embodiment (upper limit value). [Figure 7] 10 is a flowchart showing a processing procedure of a control unit. [Figure 8] 13 is a flowchart showing a processing procedure of a control unit according to the third embodiment (low frequency). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] (Embodiment 1) Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a configuration diagram showing a system including a reactive power compensator 1 according to embodiment 1 (tap switching detection). Fig. 2 is a block diagram showing a configuration example of the reactive power compensator 1. A voltage regulator 2, a reactive power compensator 1, and a power conditioner 3 are connected (connected to the same system) to a distribution line 100 (system) in which a substation is arranged.

[0025] The voltage adjustment device 2 is, for example, a distributed power source compatible SVR (Step Voltage Regulator), and performs tap switching in response to a relatively gradual voltage fluctuation in the voltage of the distribution line 100 (distribution line 100 voltage), and performs tap control so that the voltage of the distribution line 100 on the load side approaches a target voltage (so that it falls within a dead zone). When the voltage adjustment device 2 is arranged in the distribution line 100, it is assumed as an initial setting in the arrangement that the side to which a substation, which is a power source, is connected to the voltage adjustment device 2 becomes the primary side, and the side to which a load is connected becomes the secondary side. In addition, the distribution line 100 may have a loop shape, for example, from the viewpoint of ensuring redundancy, and switching in such a loop-shaped distribution line 100 may cause the connection mode of the substation and the load to be reversed, that is, the substation is connected to the secondary side, and the load is connected to the primary side.

[0026] When the impedance of the distribution line 100 to which the substation is connected is compared with the impedance of the distribution line 100 to which the load is connected, the impedance of the distribution line 100 to which the load is connected is greater than the impedance of the distribution line 100 to which the substation is connected. When the voltage regulator 2 performs tap switching, it compares the amount of change in the primary voltage with the amount of change in the secondary voltage (absolute value of the amount of change), and determines that the side with the smaller amount of change is the side to which the substation is connected (substation direction), thereby performing substation direction determination. The process related to the substation direction determination may be performed using, for example, the means disclosed in JP 2019-033638 A.

[0027] The reactive power compensator 1 is, for example, a static var compensator (SVC) 1 or a static synchronous compensator (STATCOM) 1, and is connected to a power distribution line 100 via an interconnection point 101 (SVC receiving point). The reactive power compensator 1 is arranged (connected) on the secondary side of a voltage regulator 2. The reactive power compensator 1 automatically adjusts (performs voltage compensation) the power distribution line 100 voltage to a target voltage value by outputting reactive power in response to abrupt voltage fluctuations in the voltage (power distribution line 100 voltage) of the power distribution line 100 (interconnection point 101).

[0028] The power conditioner 3 is placed (connected) on the secondary side of the reactive power compensator 1, that is, on the load side owned by the consumer. The power conditioner 3 is connected to a renewable energy generator such as a solar power generator, and includes an inverter that converts direct current to alternating current, and a microcomputer that controls the inverter and includes a communication function. Furthermore, the power conditioner 3 has an islanding prevention function. The islanding detection function is a protection function that detects that power is being supplied during a power outage by injecting reactive power into the power line to prevent islanding, and quickly disconnects the renewable energy generator from the power line.

[0029] The reactive power compensator 1 includes a control unit 11 and a reactive power output unit 12, and the reactive power output unit 12 is connected to an interconnection point 101 (SVC receiving point) in a power distribution line 100, for example, via a pole gas circuit breaker (PGB). Furthermore, the reactive power compensator 1 (control unit 11) is connected to the interconnection point 101 (SVC receiving point) via, for example, a system transformer (Tr), and acquires (detects) a voltage value of the interconnection point 101 (interconnection point voltage value).

[0030] The control unit 11 is configured with a microcomputer or the like (control box) including a storage unit such as a memory, and controls the inverter unit of the reactive power output unit 12. The control unit 11 (control box) has a CPU (Central Processing Unit) (not shown) and a storage unit such as a ROM or RAM. The control unit 11 (control box) executes control related to voltage compensation according to a control program (program product) pre-stored in the storage unit such as a ROM. When the control unit 11 performs various calculation processes and detection processes, data or information temporarily generated may be stored in the RAM.

[0031] The control unit 11 outputs a command to the reactive power output unit 12 to output leading or lagging reactive power (leading phase reactive power or lagging phase reactive power) to increase or decrease the voltage (interconnection point voltage value) at the interconnection point 101 (SVC receiving point) so as to become a set value (target voltage value) stored in the storage unit. When the reactive power compensator 1 is a STATCOM, the reactive power output unit 12 includes an inverter unit and a transformer, generates reactive power according to a command (PWM duty signal, etc.) from the control unit 11, and outputs the generated reactive power (reactive current I). In this way, the reactive power compensator 1 executes voltage compensation. Although details will be described later, the reactive power compensator 1 (control unit 11) executes an influence suppression process to suppress an influence on the substation direction determination by the voltage adjustment device 2 when executing voltage compensation.

[0032] FIG. 3 is an explanatory diagram showing voltage fluctuations (without influence suppression processing) on ​​the primary side and secondary side of the voltage regulator 2. FIG. 4 is an explanatory diagram showing voltage fluctuations (with influence suppression processing) on ​​the primary side and secondary side of the voltage regulator 2. In the illustration of this embodiment, when the voltage regulator 2 performs tap switching, the voltage fluctuations on the primary side and secondary side of the voltage regulator 2 will be explained. FIG. 3 shows the voltage fluctuations on the primary side and secondary side of the voltage regulator 2 in the case where the reactive power compensator 1 does not perform influence suppression processing and voltage compensates for the voltage fluctuation due to the tap switching. FIG. 4 shows the voltage fluctuations on the primary side and secondary side of the voltage regulator 2 in the case where the reactive power compensator 1 performs influence suppression processing. Note that in these illustrations, the explanation will be given on the assumption that the reactive power compensator 1 is arranged on the secondary side of the voltage regulator 2 and the substation is arranged on the primary side of the voltage regulator 2.

[0033] When performing processing related to substation direction determination, the voltage regulating device 2 compares the amount of change in the primary side voltage at the time of tap switching (before and after tap switching) with the amount of change in the secondary side voltage, and determines that the side with the smaller amount of change is the side to which the substation is connected (substation direction). This utilizes the fact that the system impedance of the distribution line 100 on the side to which the substation is connected is smaller than the system impedance of the distribution line 100 on the side to which the load is connected. The voltage regulating device 2 requires a time required for processing the substation direction determination (substation direction determination time), i.e., a voltage change detection time, of, for example, several tens of ms to several hundreds of ms.

[0034] In the illustration of this embodiment, the upper part shows the fluctuation of the primary voltage of the voltage regulator 2, and the lower part shows the fluctuation of the secondary voltage of the voltage regulator 2. In these illustrations, the vertical axis shows voltage, and the horizontal axis shows elapsed time. When the reactive power compensator 1 outputs reactive power according to the voltage fluctuation in the distribution line 100 (performs normal voltage compensation) without performing an influence suppression process (a process for suppressing the influence of the voltage regulator 2 on the substation direction determination), the primary voltage of the voltage regulator 2 increases by the compensation voltage of the reactive power compensator 1. That is, the primary voltage after the voltage compensation by the reactive power compensator 1 is a value obtained by adding the compensation voltage of the reactive power compensator 1 to the original primary voltage. Therefore, the primary voltage of the voltage regulator 2 increases from the voltage before tap switching to the voltage after tap switching according to the compensation voltage of the reactive power compensator 1.

[0035] The secondary voltage of the voltage regulator 2 increases by the compensation voltage of the reactive power compensator 1, but the voltage value itself is maintained at a preset value (target voltage) in the reactive power compensator 1, so the voltage before and after tap changing roughly match. In other words, the original secondary voltage minus the compensation voltage of the reactive power compensator 1 is a value lower by the compensation voltage of the reactive power compensator 1 than the voltage before tap changing.

[0036] If the reactive power compensator 1 performs voltage compensation without performing an effect suppression process when tap switching is performed in this way, the amount of change in the primary voltage before and after tap switching will be larger than the amount of change in the secondary voltage (amount of change in primary voltage > amount of change in secondary voltage). This raises the concern that the voltage regulating device 2 may erroneously determine that the substation is located on the secondary side when determining the substation direction.

[0037] In response to this, as shown in Fig. 4, when tap changing is performed, the reactive power compensator 1 performs an influence suppression process to abandon voltage compensation (reduce the reactive power output) during tap changing. That is, the reactive power compensator 1 abandons voltage compensation (reduces the reactive power output) during tap changing, thereby making it possible to return (change) the primary and secondary voltages to the original voltages without voltage compensation. When abandoning voltage compensation (reducing the reactive power output), the reactive power compensator 1 may abandon (reduce) the compensation voltage for one tap voltage width (one tap step voltage) or may abandon the compensation voltage at any value between 50% and 100% of the voltage width of the one tap.

[0038] When detecting the occurrence of tap switching, the reactive power compensation device 1 may determine that tap switching has occurred if the voltage change amount of the original interconnection point voltage value corresponds to the voltage width of one tap and if there is no significant change in the original interconnection point voltage value for a predetermined period (output abandonment time) from the detection of the voltage change (the point in time when the voltage change amount is detected).

[0039] The original interconnection point voltage value is a value obtained by subtracting the voltage value (compensated voltage value) currently compensated by the reactive power compensation device 1 from the interconnection point voltage value acquired (detected) via, for example, a system transformer (Tr), i.e., it corresponds to the interconnection point voltage value when no voltage compensation is performed (uncompensated interconnection point voltage value). The reactive power compensation device 1 periodically derives the compensation voltage value based on, for example, the amount of reactive power currently output by itself (its own device) and a system impedance input and stored in advance, and stores the compensation voltage value in the storage unit in association with the derivation time point.

[0040] In this way, the reactive power compensator 1 starts voltage compensation (output of reactive power) for voltage fluctuations caused by tap switching, but executes a process of abandoning voltage compensation (stopping output of reactive power) during the tap switching as an influence suppression process. That is, when the reactive power compensator 1 starts voltage compensation (output of reactive power) for voltage fluctuations caused by tap switching, the secondary side voltage (voltage at the interconnection point 101) changes by the voltage width of one tap, and then remains in this state for a while. After that, after a predetermined period (output abandonment time) has elapsed, the reactive power compensator 1 abandons voltage compensation (stops output of reactive power), and the compensation voltage corresponding to the voltage width of one tap changes to a voltage (original voltage) excluding this.

[0041] The time (output abandonment time) from the detection of tap switching by the reactive power compensator 1 to the abandonment of voltage compensation is, for example, several hundreds of nsec to 10 msec, which is an extremely short time (period) compared to the substation direction determination time (several tens of ms to several hundreds of ms) by the voltage regulator 2. Therefore, the voltage regulator 2 can perform the substation direction determination based on the above-mentioned original voltage change amount on the primary side and the secondary side after the reactive power compensator 1 abandons voltage compensation. As illustrated in the figure in this embodiment, in the original voltage change amount on the primary side and the secondary side after the reactive power compensator 1 abandons voltage compensation, the voltage change amount on the primary side is smaller than the voltage change amount on the secondary side (change amount on the primary side voltage<change amount on the secondary side voltage). Therefore, when performing the substation direction determination, the voltage regulator 2 can correctly determine that the substation is located on the primary side.

[0042] As described above, in the illustration of this embodiment, it is assumed that the substation is arranged on the primary side of the voltage regulator 2, but the case where the substation is arranged on the secondary side of the voltage regulator 2 is also assumed. However, when the substation is arranged on the secondary side of the voltage regulator 2, when the voltage regulator 2 performs tap switching, the primary side voltage changes by approximately one tap voltage width, and the secondary side voltage (interconnection point 101 voltage: voltage of the interconnection point 101 to which the reactive power compensator 1 is connected) does not change significantly. Therefore, regardless of the presence or absence of the reactive power compensator 1 (whether the reactive power compensator 1 performs the influence suppression process or not), the amount of voltage change on the primary side becomes large, so that the voltage regulator 2 can determine that the substation direction is the primary side even when the reactive power compensator 1 does not perform the influence suppression process.

[0043] 5 is a flowchart showing the processing procedure of the control unit 11. The control unit 11 of the reactive power compensation device 1 executes this processing (influence suppression processing) while executing reactive power output control (voltage compensation processing) corresponding to voltage fluctuations in the power distribution line 100, in accordance with a control program (program product) pre-stored in a storage unit such as a ROM.

[0044] The control unit 11 acquires an interconnection point voltage value (S101). The control unit 11 constantly or periodically acquires a voltage value (interconnection point voltage value) at an interconnection point 101 (SVC receiving point) in the power distribution line 100 via a system transformer (Tr) or a measurement transformer arranged in the vicinity of the interconnection point 101. The control unit 11 may store the acquired interconnection point voltage value in the storage unit in association with the time of acquisition (time of measurement).

[0045] The control unit 11 derives a compensation voltage value (S102). The control unit 11 periodically derives the compensation voltage value at the current time based on the reactive power (Var) currently being output and the system impedance (system impedance from the substation to the interconnection point 101: R, X) stored in the storage unit. The control unit 11 may store the derived compensation voltage value in the storage unit in association with the time of derivation.

[0046] The control unit 11 derives an uncompensated interconnection point voltage value (original interconnection point voltage value) (S103). The control unit 11 periodically derives the uncompensated interconnection point voltage value (original interconnection point voltage value) by subtracting (subtracting) the compensation voltage value from the interconnection point voltage value that is substantially at the same time. The control unit 11 may store the derived uncompensated interconnection point voltage value (original interconnection point voltage value) in the storage unit in association with the time point at which it was derived.

[0047] The control unit 11 determines whether tap switching has been performed in the voltage adjustment device 2 (S104). The control unit 11 determines whether tap switching has been performed in the voltage adjustment device 2 based on the voltage change amounts of a plurality of uncompensated interconnection point voltage values ​​derived in a predetermined processing unit time. When determining whether tap switching has been performed, the control unit 11 determines whether the voltage change amount of the uncompensated interconnection point voltage value is within a predetermined range (for example, within a range of ±10%) based on the voltage width of one tap (step voltage for one tap) in the voltage adjustment device 2. In other words, the control unit 11 determines whether the voltage change amount of the uncompensated interconnection point voltage value corresponds to (substantially equal to) the voltage width of one tap.

[0048] When the voltage change amount of the uncompensated interconnection point voltage value corresponds to the voltage width of one tap (falls within a predetermined range), the control unit 11 further judges whether or not the voltage change amount of the uncompensated interconnection point voltage value is equal to or less than a predetermined threshold value during a predetermined period of time (output abandonment time) from the time point at which the voltage change amount is detected. That is, the control unit 11 judges whether or not there is a large change in the uncompensated interconnection point voltage value (original interconnection point voltage value) during the predetermined period of time (output abandonment time) from the detection of the voltage change (time point at which the voltage change amount is detected). The predetermined period of time (output abandonment time) is stored in a storage unit of a microcomputer constituting the control unit 11 as, for example, 100 nsec to 10 msec.

[0049] The control unit 11 determines that tap switching has been performed when there is no significant change in the uncompensated interconnection point voltage value (original interconnection point voltage value) (the amount of voltage change is equal to or less than a threshold value).When the uncompensated interconnection point voltage value (original interconnection point voltage value) does not change by an amount that can occur in a voltage width of one tap, or when it fluctuates continuously, the control unit 11 determines that tap switching has not been performed (the voltage fluctuation is not a change due to tap switching).

[0050] When it is determined that tap switching has been performed (S104: YES), the control unit 11 performs a process of reducing the amount of reactive power output (abandoning voltage compensation) (S105). When it is determined that tap switching has been performed (the voltage fluctuation is due to tap switching), the control unit 11 performs a process of instantly abandoning compensation of reactive power according to the voltage fluctuation width (the voltage of one tap) due to the tap switching, that is, reducing the amount of reactive power to be output according to the voltage fluctuation width. As a result, the reactive power compensator 1 can return (change) the primary and secondary voltages to the original voltages without voltage compensation by abandoning voltage compensation (reducing the output of reactive power) during tap switching. Therefore, the voltage regulating device 2 can normally perform substation direction determination based on the original amount of voltage change on the primary and secondary sides after the reactive power compensator 1 abandons voltage compensation.

[0051] The control unit 11 determines whether a predetermined continuation processing period has elapsed (S106). The storage unit stores a continuation processing period (e.g., 2 seconds) during which the voltage adjustment device 2 continues the process of abandoning voltage compensation (reducing the output of reactive power). The control unit 11 determines whether the continuation processing period has elapsed since the time when the voltage compensation was abandoned (reduced the output of reactive power). If the continuation processing period has not elapsed (S106: NO), the control unit 11 performs loop processing to execute S106 again.

[0052] If the continuation processing period has elapsed (S106: YES), the control unit 11 cancels the process of reducing the amount of reactive power output (abandoning voltage compensation) (S107). If the continuation processing period has elapsed since the time when the control unit 11 abandoned voltage compensation (reduced the output of reactive power), the control unit 11 cancels the process of abandoning voltage compensation according to the voltage fluctuation width (the voltage of one tap) due to tap switching. Alternatively, the control unit 11 sets the voltage value after the voltage change due to tap switching as a reference voltage value, and thereafter continuously performs a process of calculating a moving average of multiple interconnection point voltage values ​​obtained periodically. Then, the control unit 11 may perform control related to voltage compensation (reactive power output control) using the calculated moving average as a reference voltage value.

[0053] When it is determined that tap switching has not been performed (S104: NO), the control unit 11 continues outputting reactive power in response to voltage fluctuations in the distribution line 100 (normal voltage compensation processing) without reducing the amount of reactive power output. When it is determined that tap switching has not been performed (the voltage fluctuations are not due to tap switching), the control unit 11 continues processing to output reactive power in response to voltage fluctuations in the distribution line 100 (i.e., normal voltage compensation processing) without reducing the amount of reactive power output. This allows voltage compensation to be performed so that the voltage value (interconnection point voltage value) at the interconnection point 101 (SVC receiving point) becomes a predetermined set value (target voltage value). After executing processing S107 or 1041, the control unit 11 ends a series of processing. Alternatively, the control unit 11 may perform loop processing to execute processing from S101 again after executing processing S107 or 1041.

[0054] (Embodiment 2) 6 is an explanatory diagram showing voltage fluctuations on the primary side and secondary side of a voltage regulator 2 according to embodiment 2 (upper limit value). In the illustration of this embodiment, the upper part shows the fluctuations in the primary side voltage of the voltage regulator 2, and the lower part shows the fluctuations in the secondary side voltage of the voltage regulator 2. In these illustrations, the vertical axis shows voltage, and the horizontal axis shows elapsed time. Note that in these illustrations, the explanation will be given on the assumption that the reactive power compensation device 1 is arranged on the secondary side of the voltage regulator 2, and the substation is arranged on the primary side of the voltage regulator 2.

[0055] The upper limit value of the compensation voltage resulting from the output of reactive power is set to any value (e.g., from 20 V to less than 50 V) between 20% and 50% (20% or more and less than 50%) of the voltage width of one tap (e.g., 100 V) in the voltage adjustment device 2. The upper limit value is set to be changeable, and a set value input (accepted) via, for example, the input / output IF of the reactive power compensation device 1 is stored in the storage unit.

[0056] In the illustration of this embodiment, the upper limit of the compensation voltage is set to less than 50% of the voltage width of one tap, and is indicated by a two-dot dashed line in the illustration. In the case where the compensation voltage upper limit is set in the reactive power compensator 1, the reactive power compensator 1 can only compensate for voltage changes up to the upper limit, and approximately 50% to 80% of the voltage width of one tap remains as a voltage change on the secondary side. In contrast, on the primary side, a voltage change of 20% to less than 50% of the voltage width of one tap occurs due to the compensation voltage. As a result, in a comparison of the magnitude of the voltage change on both sides (primary side and secondary side), a state in which the voltage change on the secondary side is larger can be maintained, and the voltage regulating device 2 can normally determine that the substation is on the primary side in the substation direction determination. Therefore, when switching taps, the amount of voltage change on the primary side is smaller than the amount of voltage change on the secondary side (amount of change in primary side voltage < amount of change in secondary side voltage), and when determining the substation direction, the voltage adjustment device 2 can correctly determine that the substation is located on the primary side.

[0057] The larger the compensation voltage upper limit value (approaching 50%), the more the voltage change amount between the primary side and the secondary side becomes balanced, and there is a concern about the influence of disturbances on the substation direction determination by the voltage regulator 2, so it is necessary to reduce the influence on the substation direction determination while suppressing voltage flicker. In response to this, by configuring the reactive power compensator 1 so that the upper limit value of the compensation voltage can be changed according to the state of the connected grid, the availability of the reactive power compensator 1 can be improved.

[0058] 7 is a flowchart showing the processing procedure of the control unit 11. The control unit 11 of the reactive power compensation device 1 executes this processing (influence suppression processing) while executing reactive power output control (voltage compensation processing) corresponding to voltage fluctuations in the power distribution line 100, in accordance with a control program (program product) pre-stored in a storage unit such as a ROM.

[0059] The control unit 11 acquires a setting value for setting an upper limit of the compensation voltage caused by outputting reactive power (S201). The control unit 11 acquires the setting value by accepting the setting value for setting the upper limit of the compensation voltage, for example, via an input / output IF or the like provided in a microcomputer constituting the control unit 11, or in response to an input from an operation panel provided in the reactive power compensation device 1. The setting value is accepted as a selectable value, for example, from 20% to 50% of the voltage width of one tap (for example, 100V) in the voltage adjustment device 2, that is, any value between 20% and less than 50% (for example, from 20V to less than 50V).

[0060] The control unit 11 sets the upper limit of the compensation voltage to the received set value (S202). The control unit 11 sets the upper limit of the compensation voltage by storing the acquired (received) set value in the storage unit.

[0061] The control unit 11 determines whether the current compensation voltage value has reached the upper limit value (S203). When performing voltage compensation, the control unit 11 outputs leading reactive power (leading-phase reactive power) when the distribution line 100 voltage (interconnection point voltage value) is lower than the target voltage value (set value) (a voltage increase is required), and outputs lagging reactive power (lagging-phase reactive power) when the distribution line 100 voltage is higher than the target voltage value (a voltage effect is required).

[0062] The control unit 11 periodically derives the compensation voltage value at the current time based on the reactive power (Var) currently being output and the system impedance (system impedance from the substation to the interconnection point 101: R, X) stored in the storage unit. The control unit 11 compares the compensation voltage value at the current time with a set upper limit value (maximum compensation voltage value) and determines whether the compensation voltage value at the current time has reached the upper limit value or not.

[0063] If the compensation voltage value at the current time point has not reached the upper limit value (S203: NO), the control unit 11 performs a loop process to execute S203 again, whereby the control unit 11 periodically or steadily continues the process of monitoring whether the compensation voltage value at the current time point has reached the upper limit value or not.

[0064] If the compensation voltage value at the current time has reached the upper limit (S203: YES), the control unit 11 limits the output amount of reactive power so that the compensation voltage value does not exceed the set upper limit (S204). If the compensation voltage value at the current time has reached the upper limit, the control unit 11 limits the output amount of reactive power so that the compensation voltage value does not become equal to or greater than the current compensation voltage value, that is, prohibits an increase in the output amount of reactive power so that the compensation voltage value does not become equal to or greater than the current reactive power amount. Therefore, when the compensation voltage value at the current time has reached the upper limit, the control unit 11 prohibits an increase in the output amount of reactive power even if there is a discrepancy between the distribution line 100 voltage (interconnection point voltage value) and the target voltage value (set value). As a result, in a comparison of the magnitude of the change amount between the primary side and secondary side voltages in the voltage regulator 2, a state in which the voltage change on the load side (secondary side when the load is placed on the secondary side) is larger can be maintained, and the voltage regulator 2 can normally perform the substation direction determination. In this way, by setting the upper limit value of the compensation voltage value by the reactive power compensator 1, it is possible to effectively perform the influence suppression process for suppressing the influence on the substation direction determination by the voltage regulator 2. After executing the process S204, the control unit 11 ends the series of processes. Alternatively, after executing the process S204, the control unit 11 may perform a loop process to execute the process from S201 again.

[0065] (Embodiment 3) 8 is a flowchart showing a processing procedure of the control unit 11 according to the third embodiment (low frequency). The control unit 11 of the reactive power compensator 1 executes this processing (influence suppression processing) while executing reactive power output control (voltage compensation processing) corresponding to voltage fluctuation in the power distribution line 100, in accordance with a control program (program product) pre-stored in a storage unit such as a ROM.

[0066] The control unit 11 acquires the interconnection point voltage value (S301). As in the process S101 of the first embodiment, the control unit 11 periodically acquires the interconnection point voltage value.

[0067] The control unit 11 derives the frequency of the voltage at the interconnection point 101 (S302). The control unit 11 derives the frequency of the voltage fluctuation at the interconnection point 101 (extracts the frequency component of the voltage at the interconnection point 101) by, for example, using a frequency analysis process or a filter circuit for a plurality of interconnection point voltage values ​​that are constantly or periodically acquired and arranged in a time series.

[0068] The control unit 11 judges whether the derived frequency is included in a predetermined low frequency range (S303). The predetermined low frequency range is stored in the storage unit. The low frequency range is set as a value that is lower than the commercial power frequency, for example, a frequency (for example, 25 Hz or less) that is half or less of the commercial power frequency from a substation, and further corresponds to a frequency (frequency of voltage flicker: for example, 10 Hz or less) due to reactive power output when the power conditioner 3 connected to the same system exerts an islanding prevention function. Note that the output of reactive power that causes voltage flicker may not be from the power conditioner 3, but may be from a reactive power output device that outputs reactive power according to various applications. In other words, the predetermined low frequency range is intended to correspond to the frequency of voltage flicker generated by reactive power output by a reactive power output device (including the power conditioner 3, etc.). The control unit 11 compares the derived frequency with the predetermined low frequency range and judges whether the derived frequency is included in the low frequency range. If the derived frequency is not included in the predetermined low frequency range (S303: NO), the control unit 11 performs a loop process to execute S303 again.

[0069] If the derived frequency is included in the predetermined low frequency range (S303: YES), the control unit 11 executes voltage compensation for the voltage fluctuation due to the derived frequency (S304). If the derived frequency is included in the predetermined low frequency range, the control unit 11 determines that the voltage fluctuation due to the derived frequency is due to the output of reactive power by the islanding prevention function of the power conditioner 3. The control unit 11 executes voltage compensation by outputting reactive power for the voltage fluctuation. This makes it possible to suppress voltage flicker caused by the power conditioner 3 (islanding prevention function) that occurs constantly, and voltage changes that occur only at the timing of tap switching due to tap switching are not suppressed. Therefore, the voltage regulating device 2 can normally perform substation direction judgment based on the voltage fluctuations on the primary side and secondary side at the time of tap switching.

[0070] Including this embodiment, the reactive power compensator 1 may perform a plurality of types of influence suppression processing. That is, the reactive power compensator 1 may be configured to be able to select the influence suppression processing according to embodiment 1, embodiment 2, and embodiment 3. In this case, the control unit 11 of the reactive power compensator 1 may receive (acquire) a selected type of influence suppression processing input from, for example, an input / output IF or an operation panel, and execute the influence suppression processing corresponding to the received selected type.

[0071] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0072] The claims may be combined with each other regardless of the form of reference. The claims include multiple dependent claims that depend on multiple dependent claims. The claims do not include multiple dependent claims that depend on a multiple dependent claim, but multiple dependent claims that depend on a multiple dependent claim may be included. [Explanation of symbols]

[0073] 1 reactive power compensator (SVC, STATCOM), 11 control unit, 12 reactive power output unit, 2 voltage regulator (distributed power source compatible SVR), 3 power conditioner (PCS), 100 distribution line, 101 interconnection point (SVC receiving point)

Claims

1. A reactive power compensation device connected to an interconnection point of a distribution line where a voltage adjustment device that performs substation direction determination as to whether a substation is connected to a primary side or a secondary side is disposed, a control unit that controls an output of reactive power in response to a voltage fluctuation in the power distribution line, The control unit performs an influence suppression process for suppressing an influence on a substation direction determination by the voltage regulator when outputting reactive power. Reactive power compensator.

2. When performing the effect suppression process, the control unit Acquire a voltage value at the interconnection point; Derive a compensation voltage value based on the output reactive power and a preset system impedance; deriving an uncompensated interconnection point voltage value indicating a voltage value at the interconnection point when no voltage compensation is performed based on the acquired interconnection point voltage value and compensation voltage value; determining whether or not tap switching of the voltage regulating device has been performed based on the voltage change amount of the derived uncompensated interconnection point voltage value; When it is determined that tap switching of the voltage regulator has been performed, the output amount of reactive power is reduced according to a compensation voltage value corresponding to a voltage fluctuation width caused by the tap switching of the voltage regulator. The reactive power compensation device according to claim 1.

3. The control unit determines that tap switching of the voltage regulator has been performed when the voltage change amount of the derived uncompensated interconnection point voltage value is within a predetermined range based on a voltage width of one tap in the voltage regulator and the voltage change amount of the uncompensated interconnection point voltage value is equal to or less than a predetermined threshold value during a predetermined period of time from the detection of the voltage change amount. The reactive power compensation device according to claim 2.

4. When the control unit executes a process of reducing an output amount of reactive power as the influence suppression process, the control unit cancels the process of reducing the output amount of reactive power after a predetermined continuous process period has elapsed. The reactive power compensation device according to claim 2 or 3.

5. The control unit performs an influence suppression process by setting an upper limit value of a compensation voltage caused by outputting reactive power to a value smaller than a voltage width of one tap in the voltage adjustment device. The reactive power compensation device according to claim 1.

6. an upper limit value of the compensation voltage by outputting reactive power is 20% to 50% of a voltage width of one tap in the voltage regulator; The control unit is Accepts any value between 20% and 50% of the voltage width of one tap as the setting value, Set the upper limit of the compensation voltage with the accepted setting value. The reactive power compensation device according to claim 5.

7. When performing the effect suppression process, the control unit Acquire a connection point voltage value at the connection point; Deriving a frequency of the interconnection point voltage based on the acquired multiple interconnection point voltage values; When the derived frequency is lower than the commercial power frequency from the substation, a process is performed to output reactive power according to the voltage fluctuation at the interconnection point. The reactive power compensation device according to claim 1.

8. A power conditioner having an islanding prevention function is connected to the distribution line, The control unit performs a process for outputting reactive power corresponding to a voltage fluctuation at the interconnection point when the derived frequency corresponds to a frequency due to reactive power output when the power conditioner exerts an islanding prevention function. The reactive power compensation device according to claim 7.

9. A reactive power output device that outputs reactive power is connected to the distribution line, The control unit performs a process for outputting reactive power corresponding to a voltage fluctuation at the interconnection point when the derived frequency corresponds to a frequency of voltage flicker generated by the reactive power output device. The reactive power compensation device according to claim 7.

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