JP2012029433A - Reactive power compensating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactive power compensating device capable of dealing with cooperative operation and steep voltage variation even if a plurality of reactive power compensating devices are installed in one electric power system.SOLUTION: The reactive power compensating device performs constant voltage control which supplies a reactive power to an electric power system so that a system voltage may be held constant. The reactive power compensating device supplies a reactive power so that the system voltage becomes within a setting width (V-V<system voltage<V+V) which has respective widths in the upper and lower sides of a reference voltage setting value V, and changes the reference voltage setting value Vgradually by comparing an average value Σ at sampling-time Tof the system voltage with the reference voltage setting value Vso that the system voltage may become within a setting width (V-V<system voltage<V+V) of the reference voltage setting value V. Therefore, while the cooperative operation is possible even if a plurality of reactive power compensating devices are installed in one electric power system, the voltage variation in the electric power system can be surely dealt with.

Description

  The present invention relates to a reactive power compensator that supplies reactive power to an electric power system and adjusts the system voltage.

  In general, in an electric power system to which a load whose electric power fluctuates greatly is connected, the voltage of the electric power system fluctuates according to a current flowing through the load. There is a reactive power compensator as one of the devices installed to suppress such voltage electric drive. This reactive power compensator supplies advanced reactive power to the power system when the system voltage is reduced, while supplying delayed reactive power to the power system when the system voltage is increased, thereby reducing voltage fluctuations. It adjusts (for example, refer patent document 1). The reactive power compensator suppresses steady voltage fluctuation while always operating according to the difference between the system voltage and the set voltage.

Japanese Examined Patent Publication No. 6-42183

  By the way, a plurality of reactive power compensators are installed in one power system in order to further stabilize the power system and suppress voltage fluctuations of the power system due to the spread of distributed power sources such as solar power generation and wind power generation. When a plurality of reactive power compensators are installed in such a single power system, if there are subtle variations in detection sensors such as current and voltage provided in each reactive power compensator, each reactive power compensator However, if the outputs are reversed, the effects may be canceled and voltage fluctuations in the power system may not be compensated. Therefore, there has been a demand for a reactive power compensator capable of cooperative operation even when a plurality of units are installed.

  In addition, if the reactive power compensator is operating with the maximum output range in order to compensate for steady voltage fluctuations, steep voltage fluctuations will occur and there will be a margin in the output of the reactive power compensator. Therefore, there is a possibility that a steep voltage fluctuation cannot be compensated. Therefore, there has been a demand for a reactive power compensator that can cope with steep voltage fluctuations.

  The present invention has been made in view of such circumstances, and its purpose is to provide reactive power that can cope with cooperative operation and steep voltage fluctuations even when a plurality of reactive power compensators are installed in one power system. It is to provide a compensation device.

In the following, means for achieving the above object and its operational effects will be described.
In the reactive power compensator of the constant voltage control system that supplies reactive power to the power system in order to stabilize the system voltage of the power system, an upper limit voltage set value and a lower limit are set above and below the voltage set value. A voltage setting value, a voltage setting range with the upper limit voltage setting value as an upper limit and a lower limit voltage setting value as a lower limit, and the voltage setting value so that the system voltage is within the voltage setting range. The gist of this is to change the process step by step.

  According to the same configuration, the upper limit voltage setting value and the lower limit voltage setting value are set above and below the voltage setting value, and the voltage setting range with the upper limit voltage setting value as the upper limit and the lower limit voltage setting value as the lower limit is set. The voltage setting value is changed stepwise so that the system voltage is within the voltage setting range of the voltage setting value. For this reason, the output of the reactive power with respect to a minute voltage fluctuation can be suppressed. Further, cooperative operation is possible in a state where a plurality of reactive power compensators are installed in one power system.

  Furthermore, since the reactive power is supplied so that the system voltage is within the voltage setting range of the voltage setting value, it is possible to output the reactive power with a margin without being adjusted to one point of the setting voltage. Therefore, it is possible to suppress a steady output of reactive power and respond immediately to a steep voltage fluctuation.

  The gist of the invention described in claim 2 is that, in the reactive power compensator according to claim 1, the voltage setting value is changed so as to approach an average value of the system voltage over a certain period of time.

  According to this configuration, the voltage setting value is changed so as to approach the average value for a certain time by comparing the average value of the system voltage for a certain time with the voltage setting value. For this reason, it is possible to suppress a large change in the voltage setting value due to steep voltage fluctuations, and it is possible to cope with voltage fluctuations.

  The invention according to claim 3 is the reactive power compensator according to claim 1 or 2, wherein the system voltage does not supply the reactive power within the voltage setting range, and the system voltage is outside the voltage setting range. The gist is to supply reactive power.

  According to this configuration, reactive power is not supplied when the system voltage is within the voltage setting range of the voltage setting value, and reactive power is supplied when the system voltage is outside the voltage setting range. For this reason, it is possible to suppress the output of reactive power.

  According to a fourth aspect of the present invention, in the reactive power compensator according to any one of the first to third aspects, the maximum voltage set value as the maximum upper limit of the upper limit voltage set value and the lower limit voltage set value A minimum voltage set value as a lower limit, and if the upper limit voltage set value is greater than or equal to the maximum voltage set value by changing the voltage set value, the maximum voltage set value is set to the upper limit voltage set value Then, when the lower limit voltage set value is less than or equal to the minimum voltage set value, the gist is to set the minimum voltage set value to the lower limit voltage set value.

  According to this configuration, when the upper limit voltage set value is equal to or greater than the maximum voltage set value, the maximum voltage set value is set to the upper limit voltage set value, and when the lower limit voltage set value is less than or equal to the minimum voltage set value, the minimum voltage set value is set. Set the value to the lower limit voltage setting value. For this reason, it is possible to suppress an excessive rise and fall of the system voltage due to voltage fluctuation. Therefore, it is possible to reliably cope with a margin of voltage fluctuations in the power system.

  According to the present invention, even if a plurality of reactive power compensators are installed in one power system, it is possible to cope with cooperative operation and steep voltage fluctuations.

The block diagram which shows schematic structure of a reactive power compensation apparatus. The figure which shows the voltage constant control of a reactive power compensation apparatus. The figure which shows control of a reactive power compensation apparatus. The figure which shows operation | movement of a reactive power compensation apparatus. The figure which shows operation | movement of a reactive power compensation apparatus. The figure which shows the operation | movement of the reactive power compensator at the time of multiple use simultaneously. The block diagram which shows the installation aspect of the reactive power compensation apparatus to an electric power grid | system.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the reactive power compensator 10 is connected in parallel to the power system 1 via a switch 2 and a transformer 3. The reactive power compensator 10 is a device that adjusts a system voltage of the power system 1, for example, 6600 V, by supplying reactive power when voltage fluctuation occurs due to the load 4 or the like connected to the power system 1. The reactive power compensator 10 of the present embodiment includes an inverter 11 in a main circuit, and a connected reactor 12 is connected to the inverter 11. The interconnecting reactor 12 is connected to the transformer 3 and connected to the power system 1 via the switch 2. A capacitor 13 for establishing a potential is connected to the inverter 11. The switch 2 is provided with two current sensors CT for detecting the current of the power system 1 and a voltage sensor PT for detecting the voltage of the power system 1 (hereinafter referred to as system voltage). Further, the reactive power compensator 10 is provided with a control device 14. Two current sensors CT and a voltage sensor PT are connected to the control device 14. The reactive power compensator 10 adjusts the voltage of the power system 1 by continuously varying the output while adjusting the reactive power flowing through the interconnection reactor 12 by the voltage difference between the system voltage and the inverter output voltage. The reactive power compensator 10 of the present embodiment is an SVG (Static Var Generator) type device.

  The reactive power compensator 10 synchronizes the output voltage of the inverter 11 with the phase of the system voltage and changes the magnitude thereof, so that a forward current flows through the interconnection reactor 12 with a delay of 90 degrees from the system voltage. That is, when viewed from the electric power system 1, the reactive power compensator 10 operates as if a variable phase advance capacitor or a shunt reactor is connected. For example, when the voltage of the power system 1 decreases due to the fluctuation of the load 4, the voltage is raised by performing the same operation as that of the phase advance capacitor as viewed from the power system 1. Moreover, when the voltage of the electric power grid | system 1 rises, seeing the electric power grid | system 1, the operation | movement similar to a shunt reactor is performed and a voltage is lowered | hung.

  The reactive power compensator 10 is a “voltage constant control” that manages the voltage at the interconnection point at a constant voltage, and a “power factor 1 control” that manages the reactive power on the power source side from the interconnection point to be zero. There are two control methods. In the constant voltage control, the reactive power is continuously generated so that the voltage at the interconnection point is located within the setting range (voltage setting range) of the reference voltage setting value. On the other hand, in the power factor 1 control, the reactive power on the load side at the interconnection point is detected, and the reactive power is continuously generated so that the reactive power on the power source side becomes zero. Note that the reactive power compensator 10 of the present embodiment suppresses voltage fluctuations by voltage constant control.

As shown in FIG. 2, the reactive power compensator 10 performs feedback control so that the system voltage becomes constant. Here, the reactive power compensator 10 controls the voltage to be stable to the voltage setting region in V _H-L having a constant width up and down criteria system voltage voltage setting value V _C. The reference voltage setting value V _C corresponds to the voltage setting value.

First, the control device 14 of the reactive power compensator 10 acquires the system voltage detected by the voltage sensor PT (step S1). Then, the control device 14 determines whether or not the system voltage is within the set range of the reference voltage set value V _C , that is, within the voltage set range V _HL (step S2). The upper limit of the setting range of the reference voltage setting value _{V C,} the reference voltage setting value _{V C} in the upper voltage range _{V H,} a _V C + _{V H} plus example 150 V, which corresponds to the upper limit voltage set value _{V CH.} The lower limit of the setting range of the reference voltage setting value _{V C,} the reference voltage setting value _{V C} lower voltage from the width _{V L,} a _V C -V _L minus example 150 V, which corresponds to the lower limit voltage set value _{V CL.} The area between the upper limit voltage set value _{V CH} and the lower limit voltage set value _{V CL} to the voltage setting region _{V H-L.}

Subsequently, when the system voltage is within the voltage setting range V _HL between the upper limit voltage setting value V _CH and the lower limit voltage setting value V _CL (V _CL <system voltage <V _CH ), The current reactive power output is fixed (step S3). In this embodiment, reactive power is not output as 0 Var. Further, when the system voltage is larger than the upper limit voltage set value V _CH (system voltage> V _CH ), the control device 14 performs constant voltage control to the upper limit voltage set value V _CH (step S4). In addition, when the system voltage is smaller than the lower limit voltage set value V _CL (system voltage <V _CL ), the control device 14 performs constant voltage control to the lower limit voltage set value V _CL (step S5). As described above, the control device 14 sequentially repeats constant voltage control based on determination of the system voltage.

Further, as shown in FIG. 3, reactive power compensator 10 of this embodiment changes the reference voltage setting value V _C based on the average value Σ of the detection voltage of the power system 1 for a predetermined time. First, the control device 14 of the reactive power compensator 10 acquires a system voltage (step S11). Subsequently, the controller 14 determines the reference voltage setting value V _C based on the average value of the detected voltage sigma (step S12). Incidentally, the average value sigma of the detection voltage is a value of the integration value V _sigma divided by the sampling time T _S of the detection voltage at the sampling time T _S. The sampling time T _S is equivalent to a predetermined time.

Subsequently, when the average value Σ of the detected voltages is larger than the reference voltage setting value V _C (Σ> V _C ), the control device 14 changes the reference voltage setting value V _C to the current reference voltage setting value V _C. The change width V _{S is} changed to a value obtained by adding, for example, 10 V (V _C = V _C + V _S ) (step S13). That is, the control unit 14 determines that the detected voltage is remained above the reference voltage setting value V _C, by changing to the upper current reference voltage setting value V _C by changing the width V _S, Provide a margin for reactive power output. Further, the control unit 14 is smaller than the average value sigma is the reference voltage setting value V _C of the detection voltage (sigma <V _C) is changed reference voltage setting value V _C from the current reference voltage setting value V _C The value is changed to a value obtained by subtracting the width V _S (V _C = V _C −V _S ) (step S14). That is, the controller 14, the detected voltage is determined to have remained in the lower than the reference voltage setting value V _C, changing into a lower current reference voltage setting value V _C by changing the width V _S Therefore, allowance is provided for the output of reactive power. Further, when the average value Σ of the detected voltages is the same as the reference voltage set value V _C (Σ = V _C ), the control device 14 keeps the reference voltage set value V _C as the current reference voltage set value V _C ( V _C = V _C ) (step S15).

Subsequently, the control unit 14, whether the voltage setting region V _H-L of the new reference voltage setting value V _C based on the determination by the mean value Σ of the detected voltage is equal to or more than the maximum value, or whether less than or equal to the minimum value Determine.

First, the control device 14 determines whether or not the lower limit voltage setting value V _CL is equal to or lower than the minimum voltage setting value V _MIN as the minimum voltage setting value (step S16). When the lower limit voltage set value V _CL is equal to or less than the minimum voltage set value V _MIN , for example, 6300 V obtained by subtracting 300 V from the original system voltage 6600 V (V _CL ≦ V _MIN ) (step S16: YES). Sets the reference voltage setting value V _C to a value obtained by adding the lower voltage width V _L to the minimum voltage setting value V _MIN (V _C = V _MIN + V _L ) (step S17). That is, the lower limit voltage setting value V _CL is set to the minimum voltage setting value V _MIN (V _CL = V _MIN ). Therefore, constant voltage control is performed based on the lower limit voltage setting value V _CL (minimum voltage setting value V _MIN ).

On the other hand, when the lower limit voltage setting value V _CL is larger than the minimum voltage setting value V _MIN (V _CL > V _MIN ) (step S16: NO), the control device 14 sets the upper limit voltage setting value V _CH to the voltage setting. It is determined whether or not the maximum voltage set value V _MAX as the maximum value is, for example, 6900 V or more obtained by adding 300 V to the original system voltage 6600 V (step S18). When the upper limit voltage setting value V _CH is equal to or higher than the maximum voltage setting value V _MAX (V _CH ≧ V _MAX ) (step S18: YES), the control device 14 sets the reference voltage setting value V _C to the maximum voltage setting. to set the value _{V MAX} minus an upper voltage range _{V H (V C = V MAX} -V H) ( step S19). That is, the upper limit voltage setting value V _CH is set to the maximum voltage setting value V _MAX (V _CH = V _MAX ). Accordingly, constant voltage control is performed based on the upper limit voltage setting value V _CH (maximum voltage setting value V _MAX ).

On the other hand, when the upper limit voltage setting value V _CH is smaller than the maximum voltage setting value V _MAX (V _CH <V _MAX ) (step S18: NO), the control device 14 acquires the system voltage and averages the detected voltages. The control based on the discrimination based on Σ is sequentially repeated.

  Next, an operation mode of the reactive power compensator 10 when one reactive power compensator 10 configured as described above is installed in one power system 1 will be described. The system voltage here is a detection voltage acquired by the reactive power compensator 10 by the voltage sensor PT.

As shown in FIG. 4, a case is described in which drops from the state where the system voltage matches the reference voltage setting value V _C to the reference voltage setting value V _C in the set lower voltage range V _L width.
First, the system voltage coincides with the reference voltage setting value V _C. Then, at the first sampling time T _S1 , the system voltage decreases from the reference voltage set value V _C within a set range, that is, within the voltage set range V _HL (V _CL <system voltage <V _CH ). At this time, the reactive power compensator 10 does not output reactive power to the power system 1. That is, the output of the reactive power compensator 10 is 0 Var. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage set value V _C as the new reference voltage set value V _C in the second sampling time T _S2 .

Subsequently, in the second sampling time T _S2 , the system voltage is maintained at the same value as the first sampling time T _S1 , in other words, within a set range (V _CL <system voltage <V _CH ). Also at this time, the reactive power compensator 10 does not output reactive power to the power system 1. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage set value V _C as the new reference voltage set value V _C at the third sampling time T _S3 . That is, it is a value obtained by subtracting twice the change width V _S from the reference voltage setting value V _{C at} the first sampling time T _S1 .

Furthermore, in the third sampling time T _S3 , the system voltage is maintained at the same value as the second sampling time T _S2 , in other words, within a set range (V _CL <system voltage <V _CH ). Also at this time, the reactive power compensator 10 does not output reactive power to the power system 1. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage setting value V _C as a new reference voltage setting value V _C. That is, the reference voltage setting value V _C is a value obtained by subtracting three times the change width V _S to the reference voltage setting value V _C at the first sampling time T _S1. Then, the system voltage and the reference voltage setting value V _C matches. Thereafter, the reactive power compensator 10 performs control based on the average value Σ of the system voltage.

Here, in a consumer, when a steep voltage fluctuation occurs, flicker or the like occurs, which is a problem. For this reason, it is important to suppress the steep voltage fluctuation corresponding to the steep voltage fluctuation. When the reactive power compensator 10 outputs the reactive power to the power system 1 at the maximum of the output range due to a small fluctuation within the setting range of the voltage setting value, that is, within the voltage setting range V _HL , it becomes steep. It becomes impossible to cope with a large voltage fluctuation. Therefore, reactive power compensator 10 of this embodiment, by close to system voltage a reference voltage setting value V _C as described above, reactive power corresponding to the immediately when the system voltage fluctuates greatly from the current value Can be output at the maximum of the output range, and steep voltage fluctuations can be suppressed.

Next, as shown in FIG. 5, the lower limit voltage setting value of the reference voltage setting value V _C unless the system voltage decreases from a state where it matches the reference voltage setting value V _C and there is no compensation by the reactive power compensator 10. The case where it falls below _VCL is demonstrated.

First, the system voltage coincides with the reference voltage setting value V _C. Then, at the first sampling time T _S1 , for example, 10 seconds, the system voltage decreases from the reference voltage set value V _C and coincides with the lower limit voltage set value V _CL . Therefore, the reactive power compensator 10 performs constant voltage control on the lower limit voltage setting value _VCL . Here, the reactive power compensator 10 outputs the advanced reactive power to the power system 1. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage set value V _C as the new reference voltage set value V _C in the second sampling time T _S2 . The first sampling time T _S1 and the second sampling time T _S2 correspond to a fixed time.

Subsequently, the system voltage at a second sampling time T _S2 is coincident with the lower limit voltage set value V _CL lower limit voltage set value V _CL new reduced further from a reference voltage setting value V _C at the first sampling time T _S1. Therefore, the reactive power compensator 10 performs constant voltage control on the lower limit voltage setting value _VCL . Here, the reactive power compensator 10 proceeds slightly less than before and outputs reactive power to the power system 1. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage set value V _C as the new reference voltage set value V _C at the third sampling time T _S3 . That is, the reference voltage setting value _{V C} in the third sampling time _{T S3} is a value obtained by subtracting twice the change width _{V S} to the reference voltage setting value _{V C} at the first sampling time _{T S1.}

Further, the system voltage further decreases from the lower limit voltage setting value V _{CL at} the second sampling time T _{S2 at} the third sampling time T _S3 , but within the setting range, that is, within the voltage setting range V _HL (V _CL <system voltage <V _CH ). Therefore, the reactive power compensator 10 does not output reactive power to the power system 1. Further, the average value Σ of the detected voltage, so than the system voltage is the reference voltage setting value V _C remained below a value smaller than the reference voltage setting value V _C. Therefore, the reactive power compensator 10 sets V _C −V _S obtained by subtracting the change width V _S from the current reference voltage setting value V _C as a new reference voltage setting value V _C. That is, the reference voltage setting value V _C is a value obtained by subtracting three times the change width V _S to the reference voltage setting value V _C at the first sampling time T _S1.

Thereafter, reactive power compensator 10, reference voltage setting value V up or system voltage matches the reference voltage setting value V _C, or the reference voltage setting value V _C matches the minimum voltage setting value V _MIN of the voltage set value Change _C step by step.

As described above, when the system voltage is about to lower than the lower limit voltage set value V _CL of the reference voltage setting value V _C, by constant voltage control to the lower limit voltage set value V _CL, based on the system voltage voltage setting value V It is possible to compensate within the set width of _C , that is, within the voltage setting range V _HL . The reference voltage setting value V _C By closer to the grid voltage, it is possible to suppress the output of the reactive power. Since reactive power can be immediately output at the maximum of the output range regardless of whether it increases or decreases with respect to steep voltage fluctuations, steep voltage fluctuations can be suppressed.

Next, an operation mode of the two reactive power compensators 10 when two reactive power compensators 10 are installed in one power system 1 will be described.
In the present embodiment, the first reactive power compensator 10a and the second reactive power compensator 10b of the reactive power compensator 10 are detected values and set values due to subtle variations in detection sensors such as current and voltage. A case where the detected value and the set value of the second reactive power compensator 10b are lower than those of the first reactive power compensator 10a will be described.

Further, as shown in FIG. 6, when the system voltage is lower than the lower limit voltage set value V _CL from the state where the system voltage is present in the voltage setting range V _HL in both the reactive power compensators 10, both reactive power compensators. A case will be described in which 10 reactive power is supplied again to return to the voltage setting range V _HL . In the load device, since the initial load is large, a large voltage drop occurs first, and the voltage gradually returns to the base.

First, the system voltage matches the reference voltage set value V _C1 in the first reactive power compensator 10a, and is higher than the reference voltage set value V _{C2 in the} second reactive power compensator 10b. A high value is detected. At this time, the reactive power compensators 10 do not output reactive power to the power system 1 because the system voltage is in the voltage setting range V _HL . That is, the outputs of both reactive power compensators 10 are 0 Var (section A).

Then, at the first sampling time T _S1 , the system voltage decreases from the reference voltage setting values V _C1 and V _{C2 of} both reactive power compensators 10 and lower than the lower limit voltage setting values V _C1L and V _C2L . Thus, first unit of the reactive power compensator device 10a, to lower than the lower limit voltage set value V _C1L above, the voltage is constant control to the lower limit voltage set value V _C1L. Subsequently, second unit of the reactive power compensator 10b is, to lower than the lower limit voltage set value V _C2L, performs constant voltage control to the lower limit voltage set value V _C2L.

Here, in the two reactive power compensators 10, the system voltage is within the setting range of the reference voltage setting values V _C1 and V _C2 , that is, within the voltage setting range V _H−L (system voltage <V _C1L and V _C2L ). Until it enters (B section), the advanced reactive power is output to the power system 1 at the maximum of the output range. Thereby, the fall of a system voltage is suppressed rather than the case where the reactive power compensation apparatus is not installed, and a system voltage can be returned at an early stage. Therefore, the system voltage rises due to the progressive reactive power of both reactive power compensators 10.

When the system voltage reaches the lower limit voltage setting value V _{C2L of the} second reactive power compensator 10b (system voltage = V _C2L ), the output of the advanced reactive power is gradually decreased (C section). At this time, since the system voltage is lower than the lower limit voltage setting value V _C1L (system voltage <V _C1L ), the first reactive power compensator 10a outputs the advanced reactive power to the power system 1 with the maximum output range. Therefore, the system voltage becomes constant due to the progressive reactive power of both reactive power compensators 10.

Then, the first reactive power compensator 10 a outputs the advanced reactive power to the power system 1 at the maximum output range. Therefore, the system voltage becomes constant due to the progressive reactive power of both reactive power compensators 10. At this time, the second reactive power compensator 10b performs voltage control because the system voltage has reached the lower limit voltage setting value V _C2L , that is, within the voltage setting range V _H−L (system voltage <V _C2L ). Stop and do not output reactive power to power system 1 (D section).

When the system voltage reaches the lower limit voltage set value V _C1L of the reactive power compensator 10a (system voltage = V _C1L ), the output of the advanced reactive power is gradually reduced (E section). Therefore, the system voltage becomes constant by the reactive power of the reactive power compensator 10a. Since the system voltage has entered the voltage setting range V _HL (system voltage <V _C1L , V _C2L ), the voltage control is stopped and _neither the reactive power _{nor the} reactive power compensators 10 a and 10 b are output to the power system 1. (F section). Therefore, the system voltage becomes constant while approaching the reference voltage setting value V _C1 and the reference voltage setting value V _C2 .

Subsequently, as the reference voltage setting value V _C1 and the reference voltage setting value V _C2 decrease by the change width V _{S at} the second sampling time T _S2 , the system voltage approaches the new reference voltage setting values V _C1 and V _C2. This coincides with the new reference voltage set value V _C2 .

Thereafter, the two reactive power compensators 10 step the reference voltage set values V _C1 and V _C2 so that the system voltage and the reference voltage set value V _C1 , and the system voltage and the reference voltage set value V _C2 match each other. Change.

Now, reactive power compensator 10 of this embodiment, a reference voltage setting value V _C set width (voltage setting range) is provided, does not output the disable the in system voltage setting range (voltage setting range) power, reactive It is possible to suppress the steady output of electric power. Therefore, even if a plurality of reactive power compensators 10 are installed in one power system 1, since reactive power is not output with a minute voltage fluctuation, cooperative operation can be performed without performing different operations. In addition, the reactive power compensator 10 can suppress the voltage fluctuation by immediately outputting the reactive power at the maximum of the output range in both the increase and decrease with respect to the steep voltage fluctuation of the system voltage. Moreover, reactive power compensator 10, by stepwise changing the reference voltage setting value V _C so as to match the system voltage, can be accommodated securely against steep voltage fluctuations in the power system 1.

In addition, as shown in FIG. 7, an automatic voltage regulator (SVR) 5 is often installed in the vicinity of each load 4 and generator 6 in the same power system 1, so that the system voltage is If the reference voltage within a set range of the set value V _C is, by adjusting the system voltage by the automatic voltage regulator 5, the voltage fluctuation in the automatic voltage regulator 5, steep voltage fluctuations in reactive power compensator 10 Correspondingly, the operation can be shared.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) above and below the reference voltage setting value _{V C1} and sets the upper limit voltage set value _{V CH} and the lower limit voltage set value _{V CL,} the upper limit voltage set value _{V CH} upper and lower limit voltage setting value _{V CL} lower limit set the setting range (voltage setting range), and changes the reference voltage setting value V _C1 such that the set width of the reference is system voltage voltage setting value V _C1 (voltage setting range) stepwise. For this reason, the output of the reactive power with respect to a minute voltage fluctuation can be suppressed. Further, cooperative operation is possible in a state where a plurality of reactive power compensators 10 are installed in one power system 1.

In addition, reactive power is supplied so that the system voltage is within the setting range (voltage setting range) of the reference voltage setting value V _C1 , so reactive power is output in a margin with a margin rather than being adjusted to one point of the setting voltage. it can. Therefore, it is possible to suppress a steady output of reactive power and respond immediately to a steep voltage fluctuation.

(2) by comparing the average value and the reference voltage setting value V _C1 of the system voltage a predetermined time, changing the reference voltage setting value V _C1 to approach the average value in a certain time. For this reason, it is possible to suppress the reference voltage set value V _{C1 from} being largely changed due to a steep voltage fluctuation, and it is possible to cope with the voltage fluctuation.

(3) Reactive power was not supplied when the system voltage was within the setting range (voltage setting range) of the reference voltage setting value V _C1 , and reactive power was supplied when the system voltage was outside the setting range (voltage setting range). For this reason, it is possible to suppress the output of reactive power.

(4) Even when the system voltage changes gradually and as a result changes greatly, the setting range (voltage setting range) of the reference voltage setting value V _C1 is limited between the upper limit and the lower limit of the setting range. It is possible to output reactive power so that the reference voltage set value V _C1 reaches a certain level.

(5) A maximum voltage setting value V _MAX as the upper limit of the upper limit voltage setting value V _CH and a minimum voltage setting value V _MIN as the lower limit of the lower limit voltage setting value V _CL are set, and the reference voltage setting value V _{C is} set. When the upper limit voltage set value V _CH is equal to or greater than the maximum voltage set value V _MAX by changing the above, the maximum voltage set value V _MAX is set to the upper limit voltage set value V _CH and the lower limit voltage set value V _CL is set to the minimum voltage set value. In the case of V _MIN or less, the minimum voltage setting value V _MIN was set to the lower limit voltage setting value V _CL . For this reason, it is possible to suppress an excessive rise and fall of the system voltage due to voltage fluctuation. Therefore, it is possible to reliably cope with a margin for a sharp voltage fluctuation of the power system 1.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the above embodiment, values such as the system voltage, the setting width, the change width, and the sampling time can be arbitrarily set according to the installation location.

In the above embodiment, as the system voltage matches the reference voltage setting value V _C, although the reference voltage setting value V _C was stepwise changed, matching within a set range of the reference is system voltage voltage setting value V _C You may change so that it does.

In the above embodiment, the setting range of the reference voltage setting value V _C is set so as not to exceed the maximum voltage setting value V _MAX and the minimum voltage setting value V _MIN , but the maximum voltage setting value V _MAX and the minimum voltage setting value V _It is not necessary to set _MIN .

In the above embodiment, it may be set to any value individually the upper voltage range V _H and the lower voltage range V _L of the reference voltage setting value V _C. For example, in accordance with the voltage fluctuation characteristics of the power system 1 in which the reactive power compensator 10 is installed, the upper voltage width V _H is reduced if the voltage is likely to increase, or is decreased if the voltage is likely to decrease. The side voltage width V _L may be reduced.

In the above embodiment, when the system voltage is stabilized within the voltage setting range V _HL , the reactive power compensator 10 does not output the reactive power to the power system 1 and sets it to 0 Var, and the voltage setting range V _HL Reactive power was supplied when exceeding. However, a constant reactive power even when stabilized in voltage setting region V _H-L may be output to the system voltage.

In the above embodiment, the comparison between the system voltage and the reference voltage setting value V _C was performed at the sampling time T _S, may be sequentially performed a comparison between the system voltage and the reference voltage setting value V _C.
In the above-described embodiment, the operation mode when one reactive power compensator 10 is installed in one power system 1 and when two reactive power compensators 10 are installed has been described. Even if installed, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Electric power system, 2 ... Switch, 3 ... Transformer, 4 ... Load, 5 ... Automatic voltage regulator (SVR), 6 ... Generator, 10 ... Reactive power compensator (SVG), 11 ... Inverter, 12 ... Linked reactor, 13 ... capacitor, 14 ... control device, CT ... current sensor, PT ... voltage sensor, V _C , V _C1 , V _C2 ... reference voltage set value as voltage set value, V _CH ... upper limit voltage set value, V _CL , V _C1L , V _C2L ... lower limit voltage setting value, V _H ... upper voltage width, V _L ... lower voltage width, V _H-L ... voltage setting range, V _S ... change width, V _MAX ... maximum voltage setting Value, V _MIN ... Minimum voltage setting value, T _S1 , T _S2 , T _S3 ... Sampling time as a fixed time, Σ ... Average value.

Claims (4)

In the reactive power compensator of the constant voltage control method for supplying reactive power to the power system in order to stabilize the system voltage of the power system,
Set the upper limit voltage set value and lower limit voltage set value above and below the voltage set value, set the upper limit voltage set value as the upper limit, and set the voltage set range with the lower limit voltage set value as the lower limit,
The reactive power compensator characterized by changing the said voltage setting value in steps so that the said system voltage may be in the said voltage setting range. The reactive power compensator according to claim 1,
The reactive power compensator characterized by changing the said voltage setting value so that it may approach the average value in the fixed time of the said system | strain voltage. The reactive power compensator according to claim 1 or 2,
The reactive power compensator, wherein the system voltage does not supply the reactive power within the voltage setting range, and supplies the reactive power when the system voltage is outside the voltage setting range. In the reactive power compensator according to any one of claims 1 to 3,
Set the maximum voltage setting value as the upper limit of the upper limit voltage setting value and the minimum voltage setting value as the lower limit of the lower limit voltage setting value,
When the upper limit voltage set value is greater than or equal to the maximum voltage set value by changing the voltage set value, the maximum voltage set value is set to the upper limit voltage set value, and the lower limit voltage set value is set to the minimum voltage set value. The reactive power compensator according to claim 1, wherein the minimum voltage set value is set to the lower limit voltage set value in the following cases.

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