JP7269847B2 - VOLTAGE CONTROL DEVICE, VOLTAGE CONTROL METHOD, VOLTAGE CONTROL PROGRAM AND VOLTAGE CONTROL SYSTEM - Google Patents

Description

The present invention relates to a voltage control device, a voltage control method, a voltage control program, and a voltage control system.

In recent years, expectations for renewable energy, which has less impact on the environment, have increased, and its introduction has been promoted. In particular, the introduction and expansion of photovoltaic (PV) power generation is remarkable. In addition, the Feed-in Tariff (FIT) has further accelerated the spread of PV introduction in both residential and non-residential areas.

With the spread and expansion of such PV, a voltage rise in the distribution system due to reverse power flow has become a problem. 2. Description of the Related Art Conventionally, voltage regulators such as a Load Raito Control Transformer (LRT) and an Automatic Voltage Regulator (SVR) are arranged in a power distribution system. Compensation control for voltage fluctuations accompanying fluctuations in power demand is performed based on the tap switching control of these voltage regulators. However, the voltage fluctuation due to the reverse power flow of the PV becomes steep because it is influenced by the weather and the like, and the LRT and SVR may not be able to catch up with the control.

On the other hand, a power conditioner (Power Conditioning Sub System: PCS) connected to the PV is equipped with an automatic voltage regulator having a voltage rise suppressing function. The voltage rise suppression function performs phase-leading reactive power control or output suppression in order to avoid deviation of the voltage at the connection point to the distribution system from the proper voltage range upper limit value. As a result, deviation from the upper limit of the distribution line voltage can be avoided in a system in which a PCS equipped with a voltage rise suppression function is interconnected. However, if the supply of power generated by the PV to the system is suppressed by the voltage rise suppression function, a power generation opportunity loss occurs. Therefore, it is important to maintain the distribution line voltage at an appropriate value while avoiding as much as possible the loss of power generation opportunities due to output suppression.

Therefore, in order to maintain the distribution line voltage at an appropriate value while avoiding power generation opportunity loss due to output suppression as much as possible, delaying the operation time of the voltage rise suppression function in consideration of cooperation with the SVR was studied. Generally, an operation time limit, which is a waiting time before starting an operation, is set to 45 seconds at the shortest in the SVR. Therefore, a technique has been proposed in which the PCS operation time limit is set longer than the SVR operation time limit, so that the SVR voltage adjustment is performed first, and the amount of output suppression by the PCS voltage rise suppression function is reduced. Based on this technology, it is currently required to set the PCS operating time limit to 200 seconds.

As a system voltage adjustment method for reverse power flow by PV, when the voltage value of the node exceeds the voltage target value, the reactive power output by the PCS is controlled based on the voltage value of the distribution substation and the information obtained from the smart meter. There is a prior art that adjusts the voltage value of the node using Further, when the active power is equal to or less than the threshold, the operating power factor of the PCS is maintained at 100%. There is Furthermore, there is a conventional technique for starting voltage suppression control of PCS when the minimum value of the output voltages of a plurality of PCS is equal to or higher than a threshold.

JP 2013-183622 A JP 2015-132988 A Japanese Patent Application Laid-Open No. 2015-211480

However, increasing the operation time limit of the PCS to 200 seconds or the like may degrade the voltage control performance. A specific case in which coordinated control with the SVR cannot be obtained is when the voltage rises locally due to variations in solar radiation. In such a case, if the operation time limit of the PCS is lengthened, it becomes difficult to control voltage fluctuations caused by sharp fluctuations in solar radiation that have been controlled by the PCS, and the possibility of voltage upper limit deviation increases.

For example, in the PCS before the operation time limit was defined as 200 seconds, almost no voltage excursion was obtained on sunny days. On the other hand, after the PCS operating time limit was set to 200 seconds, the amount of deviation significantly increased as the PC introduction rate increased. In this way, when abrupt voltage fluctuations occur, it is difficult to maintain the distribution line voltage at an appropriate value while avoiding power generation opportunity loss as much as possible.

In addition, in any of the above-mentioned conventional technologies, it is difficult to adjust the system voltage in response to abrupt voltage fluctuations when the PCS operation time limit is lengthened. is difficult to maintain.

The disclosed technology has been made in view of the above, and provides a voltage control device, a voltage control method, a voltage control program, and a voltage control system that maintain the distribution line voltage at an appropriate value while suppressing power generation opportunity loss. for the purpose.

In one aspect of the voltage control device, voltage control method, voltage control program, and voltage control system disclosed in the present application, the converter receives supply of DC power from a distributed power source, converts it to AC power, and distributes the AC power. supply to the system. The reactive power adjusting unit increases the reactive power output from the converter to lower the voltage when the interconnection point voltage of the interconnection point with respect to the distribution system exceeds the upper limit value. After the power factor of the output of the converter reaches a predetermined value in a state in which the reactive power output by the converter is increased by the reactive power adjustment unit, the output control unit controls the When the tie-point voltage exceeds the upper limit, the amount of active power and reactive power output from the converter is reduced.

In one aspect, the present invention can maintain the distribution line voltage at an appropriate value while suppressing power generation opportunity loss.

FIG. 1 is a diagram illustrating an example of a distribution system model according to an embodiment. FIG. 2 is a block diagram of a PCS according to an embodiment. FIG. 3 is an operation diagram of the voltage rise control function by the PCS according to the embodiment. FIG. 4 is a diagram showing output planes of active power and reactive power during constant power factor control. FIG. 5 is a diagram showing output planes of active power and reactive power during constant power factor control of 0.95. FIG. 6 is a flowchart of voltage rise suppression control by the PCS according to the embodiment. FIG. 7 is a diagram comparing the amount of voltage deviation and the amount of power generation opportunity loss between the voltage increase control according to the embodiment during constant power factor control and the control for starting reactive power output after the elapse of the operation time limit. FIG. 8 is a diagram comparing the amount of voltage deviation and the amount of power generation opportunity loss between voltage rise control according to the embodiment under constant power factor control of 0.95 and control that starts outputting reactive power after an operation time limit has elapsed. FIG. 9 is a diagram showing changes in the amount of voltage deviation and the amount of power generation opportunity loss when the output suppression operation time limit changes in the case of the constant operating power factor control of 1. FIG. FIG. 10 is a diagram showing changes in the amount of voltage deviation and the amount of power generation opportunity loss when the output suppression operation time limit changes in the case of constant power factor control of 0.95.

Exemplary embodiments of a voltage control device, a voltage control method, a voltage control program, and a voltage control system disclosed in the present application will be described below in detail with reference to the drawings. The voltage control device, voltage control method, voltage control program, and voltage control system disclosed in the present application are not limited to the following embodiments.

FIG. 1 is a diagram illustrating an example of a distribution system model according to an embodiment. A distribution system model 10 includes a distribution substation 1, an SVR 2, a main line 3, a transformer 4, a consumer residence 5, and a PCS 100.

A distribution substation 1 is connected to a main line 3 . The distribution substation 1 lowers the voltage of the power transmitted from the power plant, transmits the power to the main line 3 , and supplies it to each consumer's house 5 .

SVR 2 is arranged on main line 3 . The SVR 2 obtains a line voltage drop value at a predetermined point and switches the tap according to the obtained value, thereby adjusting the voltage so that the voltage at the predetermined point falls within a predetermined voltage range. The SVR2 is set with an operation time limit for adjusting the system voltage. This operation time limit is set, for example, between 45 and 120 seconds.

Hereinafter, the operation time limit of SVR2 is referred to as "SVR operation time limit". For example, when the SVR 2 detects that the voltage at a predetermined point deviates from the predetermined voltage range, the SVR 2 adjusts the voltage so that the voltage at the predetermined point falls within the predetermined voltage range after the SVR operation time limit has elapsed. This SVR operation time limit corresponds to an example of the "second period".

The transformer 4 is arranged on a low-voltage distribution line 31 branching from the main line 3 and extending to the consumer's residence 5 . The transformer 4 adjusts the voltage to the voltage used in the customer's residence 5 and supplies the adjusted voltage electricity to the customer's residence 5 .

The customer's house 5 has a PV 51 and a house load 52 which are distributed power sources. The PV 51 sends power generated using sunlight to the main line 3 via the PCS 100 and the low-voltage distribution line 31 . The residential load 52 is, for example, a home appliance, and uses power supplied via the transformer 4 .

The PCS 100 is arranged on a path connecting the transformer 4 and the PV 51 . The PCS 100 converts the DC power supplied from the PV 51 into AC power and sends the AC power to the main line 3 via the low-power distribution line 31 and the transformer 4 .

FIG. 2 is a block diagram of a PCS according to an embodiment. Next, the details of the PCS 100 will be described with reference to FIG. The connection point of the PCS 100 to the distribution line extending from the transformer 4 corresponds to an example of the "connection point to the distribution system".

The PCS 100 includes, as shown in FIG. It has an adjusting section 107 and a reactive power target value providing section 108 .

Inverter 101 receives supply of DC power from PV 51 . Further, the inverter 101 receives an input of a control signal from the inverter control section 102 for outputting a determined amount of active power and reactive power. Then, the inverter 101 converts the supplied DC power into AC power so as to output the amount of active power and reactive power specified by the control signal. After that, the inverter 101 outputs the power converted to AC power and sends it to the main line 3 via the transformer 4 . This inverter 101 corresponds to an example of a "converter".

The active power/reactive power arithmetic circuit 103 measures the voltage and current at the interconnection point to the inverter 101 . Then, the active/reactive power calculation circuit 103 calculates the output amounts of active power and reactive power at the interconnection point of the inverter 101 from the measured voltage and current. In the following description, the output amount of active power and the output amount of reactive power are referred to as active power output and reactive power output. After that, the active power/reactive power calculation circuit 103 outputs information on the calculated active power output to the active power/reactive power control section 104 and the active power adjustment section 105 . In addition, the active power reactive power calculation circuit 103 outputs information on the calculated reactive power output to the active power reactive power control section 104 and the reactive power adjustment section 107 . Further, the active/reactive power calculation circuit 103 outputs information on the interconnection point voltage to the active/reactive power control unit 104 .

Active power reactive power control section 104 has in advance information on the proper voltage range upper limit value of active power. In addition, active power reactive power control section 104 has in advance information on the minimum power factor. This minimum power factor corresponds to an example of the "predetermined value".

Furthermore, the active power reactive power control unit 104 has in advance information on the operation time limit of output suppression. This operation time limit is set longer than the SVR operation time limit. For example, this operating time limit is set to 200 seconds. The operation time limit for output suppression in the active power reactive power control unit 104 is hereinafter referred to as "output suppression operation time limit". This output suppression operation time limit corresponds to an example of the "first period".

Active power reactive power control unit 104 also has information on the rated capacity of inverter 101 in advance. Active power reactive power control section 104 also has a timer for measuring elapsed time. In addition, the active power reactive power control unit 104 stores in advance the pull-back voltage value that is the threshold for the voltage suppression recovery process.

The active power reactive power control unit 104 performs constant power factor control for controlling the operating power factor of the power output from the inverter 101 during normal operation to be constant. For example, the active power reactive power control unit 104 performs constant power factor control so that the operating power factor becomes one. The constant power factor control in which the operating power factor is 1 is hereinafter referred to as "1 constant power factor control". In this case, active power reactive power control section 104 does not output reactive power from inverter 101 during normal operation. That is, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to provide the target value of the active power output during normal operation. Furthermore, the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to set the target value of the reactive power output to zero.

Further, for example, the active power reactive power control unit 104 performs constant power factor control so that the operating power factor is 0.95. Hereinafter, constant power factor control with an operating power factor of 0.95 will be referred to as "constant power factor control of 0.95". In this case, active power reactive power control unit 104 causes inverter 101 to output reactive power so that the operating power factor is 0.95 during normal operation. That is, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to provide the target value of the active power output during normal operation. Further, the active power reactive power control unit 104 provides the reactive power target value providing unit 108 with the target value of the reactive power output at which the operating power factor becomes 0.95 according to the target value of the active power output during normal operation. instruct.

The active power reactive power control unit 104 measures the interconnection point voltage at the interconnection point to the inverter 101 . The active/reactive power control unit 104 also receives input of information on active power output and reactive power output at the interconnection point from the active/reactive power calculation circuit 103 . Next, the active power reactive power control unit 104 determines whether the voltage exceeds the proper voltage range upper limit value from the active power output and the reactive power output.

When the voltage exceeds the proper voltage range upper limit value, the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to increase the reactive power output. This increases the reactive power output from the inverter 101 and suppresses the increase in the interconnection point voltage. The active power reactive power control unit 104 repeatedly instructs the reactive power target value providing unit 108 to increase the reactive power output when the voltage continues to exceed the upper limit value of the appropriate voltage range. After that, when the voltage becomes equal to or lower than the upper limit value of the proper voltage range, the active power reactive power control section 104 instructs the reactive power target value providing section 108 to maintain the reactive power output at that time.

Also, the active power reactive power control unit 104 determines whether or not the output of the inverter 101 has exceeded the rated capacity. When the output of the inverter 101 exceeds the rated capacity, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to suppress the active power output. As a result, the active power output of the inverter 101 is reduced, and the active power output is corrected so that the output of the inverter 101 falls within the rated capacity.

Furthermore, the active power reactive power control unit 104 calculates the operating power factor of the inverter 101 using the active power output and the reactive power output at the interconnection point of the inverter 101 . Then, active power reactive power control unit 104 determines whether or not the operating power factor of inverter 101 has reached a predetermined minimum power factor. In this embodiment, the case where the minimum power factor is 0.85 will be described. If the operating power factor has not reached 0.85, the active power reactive power control unit 104 determines whether the interconnection point voltage exceeds the proper voltage range upper limit value and determines whether the output of the inverter 101 exceeds the rated capacity, The adjustment of reactive power and active power according to the determination result is repeated.

On the other hand, when the operating power factor reaches the minimum power factor, the active power reactive power control unit 104 starts its own timer at that timing. Then, the active power reactive power control unit 104 uses a timer to measure the elapsed time from when the operating power factor reaches 0.85 to when the output suppression operation time limit elapses.

By the time the output suppression operation time limit is reached, the active power reactive power control unit 104 repeatedly determines whether or not the voltage exceeds the proper voltage range upper limit value. Then, if the voltage continues to exceed the appropriate voltage range upper limit value, the active power reactive power control unit 104 determines whether the interconnection point voltage exceeds the appropriate voltage range upper limit value and determines whether the output of the inverter 101 exceeds the rated capacity. A determination is made, and the adjustment of reactive power and active power is repeated according to the determination result.

Here, when the voltage exceeds the appropriate voltage range upper limit value, it is conceivable that the deviation of the voltage at the predetermined point to be monitored from the predetermined voltage range is also detected in the SVR2. In that case, the SVR 2 adjusts the system voltage when the SVC operation time limit elapses from the time when the voltage deviates from the predetermined voltage range. The connection point voltage of the PCS 100 is also lowered by the processing of this SVR2.

If the interconnection point voltage falls below the appropriate voltage range upper limit value before the output suppression operation time limit is reached, the active power reactive power control unit 104 stops instructing to increase the output of reactive power. On the other hand, if the interconnection point voltage exceeds the upper limit value of the appropriate voltage range and continues until the output suppression operation time limit is reached, the active power reactive power control unit 104 reduces the reactive power output to the reactive power target value. The providing unit 108 is instructed. Furthermore, the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to suppress the active power output. Then, the active power reactive power control unit 104 adjusts the active power and the reactive power so that the operating power factor becomes equal to or higher than the minimum power factor.

On the other hand, when the interconnection point voltage falls below the appropriate voltage range upper limit value and stops the output increase of reactive power, the active power reactive power control unit 104 determines whether the voltage is less than the pullback voltage. If the voltage is equal to or greater than the pullback voltage, the active power reactive power control unit 104 decides to maintain the current active power output and reactive power output. In this case, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to maintain the active power output. In addition, the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to maintain the reactive power output.

On the other hand, when the voltage falls below the pull-back voltage, the active power reactive power control unit 104 executes voltage suppression recovery processing if the output of active power is being suppressed. Specifically, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to increase the active power output. Further, when reactive power is being output, the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to decrease the reactive power output. This active power reactive power control unit 104 corresponds to an example of the "output control unit".

Active power target value providing section 106 outputs a predetermined target value of active power output to active power adjusting section 105 after activation. After that, when the active power target value providing unit 106 receives an instruction to maintain the active power output from the active power reactive power control unit 104, it maintains the current target value of the active power output.

On the other hand, when an instruction to suppress the active power output is received from the active power reactive power control unit 104, the active power target value providing unit 106 reduces the current target value of the active power output by a predetermined amount. The obtained value is output to active power adjustment section 105 as a target value for the output of active power. Further, when an instruction to increase the active power output is received from the active power reactive power control unit 104, the active power target value providing unit 106 increases the target value of the active power output at that time by a predetermined amount. It is output to active power adjustment section 105 as a target value of active power output.

The active power adjustment unit 105 receives input of information on the active power output at the interconnection point of the inverter 101 from the active power reactive power calculation circuit 103 . Active power adjusting section 105 also receives an input of the target value of the active power output from active power target value providing section 106 . Then, active power adjusting section 105 calculates the difference between the actual active power output at the interconnection point of inverter 101 and the target value of the active power output. Active power adjustment unit 105 then obtains an active power output for correcting the calculated difference, and notifies inverter control unit 102 of information on the obtained active power output.

When the reactive power target value providing unit 108 receives an instruction to increase the reactive power output from the active power reactive power control unit 104, the target value of the reactive power output at that time is increased by a predetermined amount to obtain the reactive power value. It is output to reactive power adjustment section 107 as a target value of the output. Further, when the reactive power target value providing unit 108 receives an instruction to suppress the reactive power output from the active power reactive power control unit 104, the target value of the reactive power output at that time is decreased by a predetermined amount. It is output to reactive power adjustment section 107 as a target value of reactive power output. Further, when an instruction to maintain the reactive power output is received from the active power reactive power control unit 104, the reactive power target value providing unit 108 maintains the target value of the reactive power output at that time.

Reactive power adjustment unit 107 receives input of information on the reactive power output at the interconnection point of inverter 101 from active power reactive power calculation circuit 103 . The reactive power adjustment unit 107 also receives an input of the target value of the reactive power output from the reactive power target value providing unit 108 . Then, the reactive power adjustment unit 107 calculates the difference between the actual reactive power output at the interconnection point of the inverter 101 and the target value of the reactive power output. Then, reactive power adjustment section 107 obtains a reactive power output for correcting the calculated difference, and notifies inverter control section 102 of the obtained reactive power output.

Inverter control unit 102 receives from active power adjustment unit 105 a notification of the output amount of active power to be output from inverter 101 . Inverter control section 102 also receives from reactive power adjustment section 107 a notification of the output amount of reactive power to be output from inverter 101 . Then, the inverter control unit 102 outputs to the inverter 101 a control signal for outputting the specified output amounts of active power and reactive power.

Next, changes in reactive power and voltage when the voltage rise control function of the PCS 100 according to the present embodiment operates will be described with reference to FIG. FIG. 3 is an operation diagram of the voltage rise control function by the PCS according to the embodiment. The horizontal axis in FIG. 3 represents the passage of time.

In FIG. 3, a graph 201 represents changes in the connection point voltage of the PCS 100 . A graph 202 represents changes in the amount of reactive power output. A graph 203 represents changes in the suppression amount of output suppression. Furthermore, the upper limit Th represents the upper limit of the appropriate voltage range. Also, time TW1 represents the SVR operation time limit. Also, time TW2 represents an output suppression operation time limit.

In FIG. 3, at time T1, the connection point voltage of the PCS 100 exceeds the upper limit value Th. At time T1 when the connection point voltage of the PCS 100 exceeds the upper limit value Th, the PCS 100 starts outputting reactive power as indicated by a graph 202 . As a result, as shown in graph 201, the rise in the interconnection point voltage is suppressed compared to dotted line 204 when reactive power is not output.

After that, at time T2, the operating power factor falls below the minimum power factor of 0.85. In this case, the PCS 100 starts measuring the passage of time until the time TW2, which is the output suppression operation time limit, elapses at time T2. Also, for example, at this time SVR2 detects deviation of the system voltage from the predetermined voltage range. In this case, at time T2, SVR2 starts measuring the elapsed time until time TW1, which is the SVR operation time limit, elapses. Time TW1 is shorter than time TW2. For example, time TW1 is 45 seconds and time TW2 is 200 seconds.

In this case, the operating power factor remains at 0.85 even after time TW2 has passed. Therefore, at time T3 when time TW2 has elapsed, the PCS 100 starts output suppression as shown in graph 203 . When the PCS 100 performs output suppression, the reactive power output also decreases as shown in graph 202 . Then, at time T4, the connection point voltage of the PCS 100 becomes less than the upper limit value Th. Therefore, after time T4, the PCS 100 stops increasing the output suppression amount and maintains the output at that time. After that, when the voltage falls below the pull-back voltage, the PCS 100 implements an increase in active power output and a decrease in reactive power output.

Next, changes in active power output and reactive power output when the voltage rise control function of the PCS 100 according to the present embodiment operates when performing constant power factor control of 1 will be described with reference to FIG. FIG. 4 is a diagram showing output planes of active power and reactive power during constant power factor control. The horizontal axis of FIG. 4 represents active power output, and the vertical axis represents reactive power output. Curve 301 in FIG. 4 represents the rated capacity of PCS 100 . In this case, the PCS 100 executes constant power factor control with an operating power factor of 1.

The PCS 100 outputs active power indicated by a vector 311 during normal operation. Also, since the operating power factor is 1, the PCS 100 does not output reactive power. In this case, PCS 100 outputs active power at output quantity 321 . After that, when the interconnection point voltage exceeds the upper limit value of the appropriate voltage range, the PCS 100 starts outputting reactive power. Then, the PCS 100 gradually increases the reactive power output as indicated by the vector 312 if the connection point voltage continues to exceed the appropriate voltage range upper limit value.

Also, although not shown in FIG. 4, when the output exceeds the rated capacity represented by the curve 301, the PCS 100 reduces the active power output to correct the active power output so that the output stays within the rated capacity. .

Here, by increasing the reactive power output, the active and reactive power outputs reach a point 322 where the operating power factor reaches the minimum power factor 302 . When the operating power factor reaches a point 322 below the minimum power factor 302 and the tie-point voltage exceeds the proper voltage range upper limit, the PCS 100 maintains the output of active power and reactive power. Standby for the suppression operation time limit.

After that, when the operating power factor is below the minimum power factor 302 and the interconnection point voltage is above the upper limit value of the proper voltage range even after the output suppression operation time limit has passed, the PCS 100 starts output suppression. As a result, the PCS 100 reduces both the active power output and the reactive power output while maintaining the state where the operating power factor is the minimum power factor 302 as indicated by the vector 313 . Then, at point 323, the interconnection point voltage becomes less than the upper limit value of the appropriate voltage range. Therefore, the PCS 100 stops increasing the suppression amount of output suppression to maintain the active power output and reactive power output at point 323 .

Next, changes in the active power output and the reactive power output when the voltage rise control function of the PCS 100 according to the present embodiment operates when the constant power factor control of 0.95 is performed will be described with reference to FIG. FIG. 5 is a diagram showing output planes of active power and reactive power during constant power factor control of 0.95. Curve 331 in FIG. 5 represents the rated capacity of PCS 100 . In this case, the PCS 100 executes constant power factor control with an operating power factor of 0.95.

The PCS 100 outputs active power indicated by a vector 341 during normal operation. Further, since constant power factor control with an operating power factor of 0.95 is performed, the PCS 100 outputs reactive power so that cos φ becomes 0.95. In this case, PCS 100 outputs active and reactive power at point 351 on power factor 333 . After that, when the interconnection point voltage exceeds the proper voltage range upper limit value, the PCS 100 starts increasing the reactive power output. Then, the PCS 100 gradually increases the reactive power output as indicated by the vector 342 if the connection point voltage continues to exceed the upper limit value of the proper voltage range.

Having increased the reactive power output, the real and reactive power outputs reach a point 352 where the operating power factor is below the minimum power factor 332 . When the operating power factor reaches a point 352 below the minimum power factor 332 and the tie-point voltage exceeds the voltage proper range upper limit, the PCS 100 maintains the active power output and the reactive power output, and outputs Standby for the suppression operation time limit.

After that, when the operating power factor is below the minimum power factor 332 and the interconnection point voltage exceeds the upper limit value of the appropriate voltage range even after the output suppression operation time limit has passed, the PCS 100 starts output suppression. As a result, the PCS 100 reduces both the active power output and the reactive power output while maintaining the state where the operating power factor is the minimum power factor 332 as indicated by vector 343 . At point 353, the interconnection point voltage becomes less than the upper limit value of the appropriate voltage range. Therefore, PCS 100 stops increasing the suppression amount of output suppression to maintain the active power output and reactive power output at point 353 .

Next, with reference to FIG. 6, the flow of voltage rise suppression control by the PCS 100 according to the embodiment will be described. FIG. 6 is a flowchart of voltage rise suppression control by the PCS according to the embodiment.

The active/reactive power calculation circuit 103 and the active/reactive power control unit 104 detect the interconnection point voltage at the interconnection point with the power distribution system of the PCS 100 (step S1). The active power reactive power calculation circuit 103 calculates active power output and reactive power output from the detected interconnection point voltage. Then, the active power/reactive power calculation circuit 103 notifies the active power/reactive power control section 104 and the active power adjustment section 105 of the calculated active power output. In addition, the active power reactive power calculation circuit 103 notifies the calculated reactive power output to the active power reactive power control section 104 and the reactive power adjustment section 107 .

The active power reactive power control unit 104 determines whether or not the interconnection point voltage exceeds the proper voltage range upper limit value (step S2).

When the interconnection point voltage exceeds the upper limit value of the appropriate voltage range (step S2: Yes), the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to increase the reactive power output. The reactive power target value providing unit 108 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by increasing the reactive power output at that time by a predetermined amount as the target value of the reactive power output to the reactive power adjusting unit. 107. The reactive power adjustment unit 107 compares the reactive power output target value acquired from the reactive power target value providing unit 108 with the reactive power output at that time acquired from the active power reactive power calculation circuit 103 to determine whether the reactive power output is Information on the reactive power output corrected to the target value is provided to the inverter control unit 102 . Inverter control section 102 controls inverter 101 to output reactive power based on the reactive power output acquired from reactive power adjustment section 107 . This increases the reactive power output from inverter 101 (step S3).

Next, the active power reactive power control unit 104 determines whether or not the output of the inverter 101 exceeds the rated capacity (step S4). If it is within the rated capacity (step S4: No), the active power reactive power control unit 104 proceeds to step S6.

On the other hand, if the output of inverter 101 exceeds the rated capacity (step S4: affirmative), active power reactive power control unit 104 instructs to reduce the active power output so that the output of inverter 101 falls within the rated capacity. to the active power target value providing unit 106 . The active power target value providing unit 106 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by decreasing the active power output at that time by a predetermined amount as the target value of the active power output to the active power adjusting unit. 105. The active power adjustment unit 105 compares the target value of the active power output acquired from the active power target value providing unit 106 with the current active power output acquired from the active power reactive power calculation circuit 103 to determine whether the active power output is Information on the active power output corrected to the target value is provided to the inverter control unit 102 . Inverter control section 102 controls inverter 101 to output active power based on the active power output acquired from active power adjusting section 105 . This corrects the active power output from the inverter 101 (step S5).

Next, the active power reactive power control unit 104 calculates the operating power factor of the inverter 101 using the information of the active power output and the reactive power output acquired from the active power reactive power calculation circuit 103 . Then, active power reactive power control unit 104 determines whether or not the operating power factor of inverter 101 has exceeded the minimum power factor of 0.85 (step S6). If the operating power factor is 0.85 or higher (step S6: No), the voltage rise suppression control process proceeds to step S15.

On the other hand, when the operating power factor is less than 0.85 (step S6: affirmative), active power reactive power control unit 104 starts measurement by a timer if its own timer is not started. Also, when the own timer is running, the active power/reactive power control unit 104 acquires the elapsed time from the timer. Then, the active power reactive power control unit 104 determines whether or not the standby time has exceeded the output suppression control operation time limit (step S7). If the standby time has not exceeded the output suppression control operation time limit (step S7: No), the voltage rise suppression control process proceeds to step S15.

On the other hand, when the standby time exceeds the output suppression control operation time limit (step S7: Yes), the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to decrease the output of reactive power. . The reactive power target value providing unit 108 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by decreasing the reactive power output at that time by a predetermined amount as the target value of the reactive power output to the reactive power adjusting unit. 107. The reactive power adjustment unit 107 compares the reactive power output target value acquired from the reactive power target value providing unit 108 with the reactive power output at that time acquired from the active power reactive power calculation circuit 103 to determine whether the reactive power output is Information on the reactive power output corrected to the target value is provided to the inverter control unit 102 . Inverter control section 102 controls inverter 101 to output the reactive power output obtained from reactive power adjustment section 107 . This reduces the reactive power output from the inverter 101 (step S8).

Furthermore, the active power reactive power control unit 104 instructs the active power target value providing unit 106 to decrease the active power output. The active power target value providing unit 106 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by decreasing the active power output at that time by a predetermined amount as the target value of the active power output to the active power adjusting unit. 105. The active power adjustment unit 105 compares the target value of the active power output acquired from the active power target value providing unit 106 with the current active power output acquired from the active power reactive power calculation circuit 103 to determine whether the active power output is The active power output amount corrected to the target value is provided to the inverter control unit 102 . Inverter control section 102 controls inverter 101 to output the active power output acquired from active power adjusting section 105 . As a result, the active power output from inverter 101 is reduced (step S9). After that, the process of voltage rise suppression control proceeds to step S15.

On the other hand, if the interconnection point voltage is equal to or lower than the upper limit value of the proper voltage range (step S2: No), the active power reactive power control unit 104 determines whether the interconnection point voltage is less than the pullback voltage (step S10). If the interconnection point voltage is equal to or higher than the pull-back voltage (step S10: No), the voltage rise suppression control process proceeds to step S15.

On the other hand, when the interconnection point voltage is less than the pull-back voltage (step S10: affirmative), the active power reactive power control unit 104 determines whether or not the output of active power is suppressed (step S11 ). If the active power output is suppressed (step S11: No), the active power reactive power control unit 104 instructs the active power target value providing unit 106 to increase the active power output. The active power target value providing unit 106 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by increasing the active power output at that time by a predetermined amount as the target value of the active power output to the active power adjusting unit. 105. The active power adjustment unit 105 compares the active power output target value acquired from the active power target value providing unit 106 with the current active power output amount acquired from the active power reactive power calculation circuit 103, and determines the active power output. provides the inverter control unit 102 with information on the active power output corrected so that is the target value. Inverter control section 102 controls inverter 101 to output the active power output acquired from active power adjusting section 105 . This increases the active power output from inverter 101 (step S12). After that, the process of voltage rise suppression control proceeds to step S15.

On the other hand, if the active power output is not suppressed (step S11: affirmative), the active power and reactive power control unit 104 determines whether or not the reactive power output is suppressed (step S13). If the output of reactive power is not suppressed (step S13: affirmative), the voltage rise suppression control process proceeds to step S15.

On the other hand, if the output of reactive power is suppressed (step S13: NO), the active power reactive power control unit 104 instructs the reactive power target value providing unit 108 to decrease the reactive power output. The reactive power target value providing unit 108 receives the instruction from the active power reactive power control unit 104, and sets the output amount obtained by decreasing the reactive power output at that time by a predetermined amount as the target value of the reactive power output to the reactive power adjusting unit. 107. The reactive power adjustment unit 107 compares the reactive power output target value acquired from the reactive power target value providing unit 108 with the reactive power output at that time acquired from the active power reactive power calculation circuit 103 to determine whether the reactive power output is Information on the reactive power output corrected to the target value is provided to the inverter control unit 102 . Inverter control section 102 controls inverter 101 to output the reactive power output obtained from reactive power adjustment section 107 . This reduces the reactive power output from the inverter 101 (step S14). After that, the process of voltage rise suppression control proceeds to step S15.

The active power reactive power control unit 104 determines whether or not to stop the operation based on whether or not the operator has input an instruction to stop the operation (step S15). If the operation is not to be stopped (step S15: No), the voltage rise suppression control process returns to step S1. On the other hand, if the operation is to be stopped (step S15: affirmative), the active power reactive power control unit 104 ends the voltage rise suppression control process.

FIG. 7 is a diagram comparing the amount of voltage deviation and the amount of power generation opportunity loss between the voltage increase control according to the embodiment during constant power factor control and the control for starting reactive power output after the elapse of the operation time limit. FIG. 7 is a simulation result when the diffusion rate of the PV 51 in consumer residences 5 is set to 100% and the output suppression operation time limit is set to 200 seconds in the distribution system model 10 shown in FIG. The voltage deviation amount is a time-integrated value of the voltage deviation amount from the proper range of the distribution line voltage of all the consumer houses 5 during the simulation period. The amount of power generation opportunity loss is the time integrated value of the amount of output suppression in all consumer residences 5 during the simulation period.

A graph 401 in FIG. 7 is a graph representing the amount of voltage deviation in control for starting reactive power output after the operation time limit has elapsed. A graph 402 is a graph representing the amount of power generation opportunity loss in control for starting reactive power output after the operation time limit has elapsed. Also, a graph 411 is a graph representing the amount of voltage deviation in the voltage increase control according to the embodiment. A graph 412 is a graph representing the power generation opportunity loss amount in the voltage increase control according to the example. The vertical axis on the left side of FIG. 7 represents the amount of voltage deviation. Also, the vertical axis on the right side of the paper represents the amount of power generation opportunity loss.

As shown in graphs 401 and 402, if the operation time limit until reactive power output and output suppression is set to 200 seconds, in the control that starts reactive power output after the operation time limit has elapsed, the output suppression operation is delayed because the operation time limit is long. Generation opportunity loss decreases, but voltage excursion increases. On the other hand, in the voltage increase control according to the embodiment, as shown in graph 411, the amount of voltage deviation is greatly suppressed. In addition, as shown in graph 412, the voltage increase control according to the embodiment reduces the loss of power generation opportunity to some extent.

FIG. 8 is a diagram comparing the amount of voltage deviation and the amount of power generation opportunity loss between the voltage rise control according to the embodiment under constant power factor control of 0.95 and the control that starts outputting reactive power after the operation time limit has elapsed. be. FIG. 8 is a simulation result when the penetration rate of the PV 51 in the customer's house 5 is set to 100% and the output suppression operation time limit is set to 200 seconds in the distribution system model 10 shown in FIG.

A graph 403 in FIG. 8 is a graph representing the amount of voltage deviation in control for starting output of reactive power after the operation time limit has elapsed. A graph 404 is a graph representing the amount of power generation opportunity loss in control to start outputting reactive power after the operation time limit has elapsed. A graph 413 is a graph representing the amount of voltage deviation in the voltage increase control according to the embodiment. A graph 414 is a graph representing the power generation opportunity loss amount in the voltage increase control according to the example. The vertical axis on the left side of FIG. 8 represents the amount of voltage deviation. Also, the vertical axis on the right side of the paper represents the amount of power generation opportunity loss. In this case, the amount of deviation from the power supply is generally lower than in the constant power factor control of 1. This is because the constant power factor control of 0.95 outputs reactive power in all the consumer's homes 5 even in normal times, thereby suppressing the voltage rise.

In the control for starting reactive power output after the operation time limit has elapsed, the amount of power generation opportunity loss shown in graph 404 also increases due to the extension of the operation time limit. This is thought to be due to the fact that the range of deviation from the voltage upper limit has increased due to the lengthening of the operation time limit, and the number of PCS 100 that start suppressing the output has increased. On the other hand, in the voltage rise control according to the embodiment, as shown in graphs 411 and 412, the amount of voltage deviation and the loss of power generation opportunity are different from the control that starts reactive power output after the operation time limit represented by graphs 403 and 404. Both are greatly improved. The decrease in the amount of power generation opportunity loss is due to the increase in the number of PCS 100 that suppress the voltage rise by the reactive power output operation in the voltage rise control according to the embodiment, and the decrease in the opportunities to implement the output suppression.

In this manner, the PCS 100 according to the embodiment can reduce the amount of voltage upper limit deviation and the amount of power generation opportunity loss compared to control that starts reactive power output after the operation time limit has elapsed. Furthermore, the PCS 100 according to the embodiment can further reduce the voltage upper limit deviation amount and the power generation opportunity loss amount by using the constant power factor control together.

Next, with reference to FIGS. 9 and 10, changes in the amount of voltage deviation and the amount of power generation opportunity loss due to changes in the output suppression operation time limit in the PCS 100 according to this embodiment will be described. FIG. 9 is a diagram showing changes in the amount of voltage deviation and the amount of power generation opportunity loss when the output suppression operation time limit changes in the case of the constant operating power factor control of 1. FIG. FIG. 10 is a diagram showing changes in the amount of voltage deviation and the amount of power generation opportunity loss when the output suppression operation time limit changes in the case of constant power factor control of 0.95. In both FIGS. 9 and 10, the vertical axis on the left side of the paper represents the amount of voltage deviation, and the vertical axis on the right side of the paper represents the amount of power generation opportunity loss. In both FIGS. 9 and 10, the horizontal axis represents the operation time limit.

A graph 501 in FIG. 9 is a graph representing changes in the amount of voltage deviation. A graph 502 is a graph representing changes in the amount of power generation opportunity loss. As shown in the graph 501, when the power factor is controlled to be 1, the voltage deviation amount tends to increase and the power generation opportunity loss amount tends to decrease as the output suppression operation time limit increases. In particular, this tendency can be remarkably confirmed near the operation time limit of 100 seconds. In this case, there is a trade-off relationship between the amount of voltage deviation and the amount of power generation opportunity loss.

A graph 511 in FIG. 10 is a graph representing changes in the amount of voltage deviation. A graph 512 is a graph representing changes in the amount of power generation opportunity loss. During constant power factor control of 0.95, power generation opportunity loss is avoided when the output suppression operation time limit is 50 seconds or longer, and voltage excursion can be avoided at any operation time limit.

Voltage control devices such as SVR2s and other LRTs in distribution systems are often set to settling times between 45 and 120 seconds. With this in mind, voltage excursions of longer duration than these can be controlled with voltage control devices such as SVR2 or other LRTs. Therefore, the output suppression operation time limit of the PCS 100 according to the embodiment can be set to 200 seconds in consideration of cooperation with the SVR 2 and the like. However, it is preferable that the output suppression operation time limit is set based on the actual state of the distribution system, the cost, and the like.

As described above, the voltage control apparatus according to the present embodiment immediately starts outputting phase-leading reactive power to suppress the voltage when the PCS interconnection point voltage exceeds the upper limit value of the proper voltage range. After that, when the operation time limit elapses after the operating power factor exceeds the minimum power factor, the voltage control device according to the present embodiment starts output suppression. As a result, the voltage can be lowered while delaying the time to start suppressing the output.

By starting to suppress the voltage immediately after the interconnection point voltage exceeds the upper limit value of the appropriate voltage range, the amount of voltage deviation can be reduced. In addition, by delaying the start of output suppression, if the interconnection point voltage falls below the upper limit of the appropriate voltage range due to voltage adjustment by a voltage regulator such as an SVR in addition to the output of reactive power, the PCS output will be suppressed. can be avoided, and the amount of power generation opportunity loss can be reduced. That is, it is possible to maintain the distribution line voltage at an appropriate value while suppressing power generation opportunity loss.

In the above description, the PV is used as an example of the power supply source, but any dividing power source that supplies power to the distribution system, such as a storage battery, may be used.

1 Distribution substation 2 SVR
3 main line 4 transformer 5 customer house 10 distribution system model 51 PV
52 Residential load 100 PCS
101 inverter 102 inverter control unit 103 active power reactive power calculation circuit 104 active power reactive power control unit 105 active power adjustment unit 106 active power target value providing unit 107 reactive power adjustment unit 108 reactive power target value providing unit

Claims (7)

a converter that receives supply of DC power from distributed power sources, converts it to AC power, and supplies the AC power to a distribution system;
a reactive power adjustment unit that increases the reactive power output by the converter to decrease the interconnection point voltage when the interconnection point voltage of the interconnection point with respect to the distribution system exceeds an upper limit value;
After the power factor of the output of the converter reaches a predetermined value in a state where the reactive power output by the converter is increased by the reactive power adjustment unit, after a first period elapses, the interconnection point voltage is and an output control unit that reduces output amounts of active power and reactive power output from the converter when the upper limit value is exceeded. The output control unit is regulated by a voltage regulator that starts operating after a second period shorter than the first period has passed after the power factor reaches the predetermined value, and lowers the voltage of the distribution system. When the interconnection point voltage after the first period exceeds the upper limit value after the first period has elapsed, the amount of active power and reactive power output from the converter is reduced. The voltage control device according to . 3. The output control unit reduces the output amount of the active power output from the converter when the output from the converter exceeds the rated capacity of the converter. A voltage regulator as described. The output control unit performs power factor constant control for adjusting the power factor of the output of the converter to a predetermined value before the reactive power output by the converter is increased by the reactive power adjustment unit,
When the power factor is adjusted to the predetermined value by the output control unit and the interconnection point voltage exceeds the upper limit, the reactive power adjustment unit increases the reactive power output from the converter. The voltage control device according to any one of claims 1 to 3, wherein the connection point voltage is lowered. DC power supplied from distributed power sources is converted to AC power by a converter and supplied to the distribution system,
Measure the connection point voltage and current of the connection point to the distribution system,
When the measured interconnection point voltage exceeds an upper limit value, increasing the reactive power output from the converter to decrease the interconnection point voltage,
When the interconnection point voltage exceeds the upper limit after a first period has passed since the power factor of the output of the converter reaches a predetermined value in a state where the reactive power output by the converter is increased and reducing the amount of active power and reactive power output from said converter. DC power supplied from distributed power sources is converted to AC power by a converter and supplied to the distribution system,
Measure the connection point voltage and current of the connection point to the distribution system,
When the measured interconnection point voltage exceeds an upper limit value, increasing the reactive power output from the converter to decrease the interconnection point voltage,
When the interconnection point voltage exceeds the upper limit after a first period has passed since the power factor of the output of the converter reaches a predetermined value in a state where the reactive power output by the converter is increased and a voltage control program for causing a computer to execute a process of reducing output amounts of active power and reactive power output from said converter. A power regulation system comprising a distributed power source, a distribution system, a voltage controller, and a voltage regulator arranged in the distribution system,
The voltage control device is
a converter that receives supply of DC power from the distributed power supply, converts it to AC power, and supplies the AC power to a distribution system;
a reactive power adjustment unit that increases the reactive power output by the converter to decrease the interconnection point voltage when the interconnection point voltage of the interconnection point with respect to the distribution system exceeds an upper limit value;
After the power factor of the output of the converter reaches a predetermined value in a state where the reactive power output by the converter is increased by the reactive power adjustment unit, after a first period elapses, the interconnection point voltage is An output control unit that reduces the output amount of active power and reactive power output from the converter when the upper limit value is exceeded,
The voltage control system, wherein the voltage regulator starts to operate and lowers the voltage of the distribution system after the power factor reaches the predetermined value and a second period shorter than the first period elapses. .

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