JP2016034217A - Isolated operation detector and isolated operation detection method, and controller for detecting isolated operation and distributed power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reactive power injected into a power system from being cancelled, to securely detect isolated operation even when the reactive power balances with load reactive power.SOLUTION: An isolated operation detection method includes: a first step of injecting reactive power to a power system; a second step of additionally injecting reactive power having a preset phase within a first period, when already injected reactive power has balanced with load reactive power; a third step of determining interference between the already injected reactive power and additionally injected reactive power, by using the absolute value of a difference between a value of a frequency deviation at the time of the additional injection at the second step and a value of a frequency deviation at the time at which a second period shorter than the first period has passed; a fourth step of further injecting additional injection reactive power having a phase obtained by reversing a phase of the additionally injected reactive power, when a result of the determination at the third step has shown interference; and a fifth step of continuing injection of additional reactive power having the same phase as the additionally injected reactive power injected at the second step during the remaining period until the first period has passed from the time of additional injection at the second step, when the result of the determination at the third step has shown non-interference.SELECTED DRAWING: Figure 5

Description

  The present invention includes an isolated operation detection device and an isolated operation detection method for detecting whether or not a distributed power supply device is disconnected from an electric power system and operated independently, an isolated operation detection control device, and the control device. The present invention relates to a distributed power supply.

  The isolated operation in the distributed power supply device is a state in which when the power system is stopped, the distributed power supply device is operated independently and power is supplied to the local system load. Power system outages are caused by factors such as construction or accidents.

  Typical distributed power sources connected to the power system are solar power generation devices, wind power generation devices, engine generators, power storage devices, and fuel cells. In these distributed power supplies, power supply means having different characteristics or properties, such as solar cells, storage batteries, and fuel cells, are connected to the power system, so that an inverter function that adapts the frequency and voltage to the power system, and the power system Many power conditioners with built-in protection devices for detecting abnormalities have been proposed.

  A distributed power supply device that supplies power to home appliances, for example, by connecting a distributed power supply device including the power supply means described above and a power conditioner that converts direct current to alternating current to a power system has been put into practical use. Yes.

  In this type of distributed power supply, in order to ensure the safety of construction work in the power system at the time of power failure and work power failure, the operation of the inverter on the distributed power supply side is stopped or a switch The function of disconnecting the distributed power supply device from the power system by actuating the connection to prevent the isolated operation of the distributed power supply device is indispensable. This function is called an isolated operation detection function.

  As one of methods for detecting islanding, a method for injecting reactive power into the power system has already been proposed. In the isolated operation detection device using this method, the frequency variation caused by the injected reactive power is detected to detect the isolated operation of the distributed power supply device.

  On the other hand, in the method of injecting reactive power into the power system, when reactive power is injected from the isolated operation detection device, the reactive power being injected is balanced with the reactive power of the load. There is a phenomenon that even if the distributed power supply device is operated independently, frequency fluctuations cannot be caused by the reactive power being injected. That is, the method of injecting reactive power into the power system has a problem that the isolated operation state may be continued without detecting the isolated operation.

  Under the technical background as described above, the injection reactive power from the control device and the reactive power in the load (hereinafter referred to as “load reactive power”) are balanced to generate an isolated operation, and the isolated operation is detected. When the reactive power injection is insufficient, the reactive power that is already injected (hereinafter referred to as “already injected reactive power”) is additionally injected (hereinafter referred to as “additional injection reactive power”) or An isolated operation detection method that can detect the isolated operation of the distributed power supply apparatus by enabling the injection of “additional reactive power”) has been proposed (see, for example, Patent Document 1 below).

  In the method of Patent Document 1, when the injected reactive power and the load reactive power are balanced and the reactive power injection for the isolated operation is insufficient, the injected reactive power and the additional injected reactive power cancel each other. In order not to be performed, control is performed so that the phase advance or delay of the already injected reactive power coincides with the phase advance or delay of the additional injected reactive power.

JP 2009-11037 A

  As described above, in the method of Patent Document 1, control is performed to match the phase advance or delay of already injected reactive power with the phase advance or delay of additional injected reactive power, but one distributed power supply device is provided. If it is only, it will not cancel out reactive power.

  However, since the single operation detection device needs to be provided for each individual distributed power supply device, for example, when there are two distributed power supply devices, the single operation detection device is configured to have two single operation detection devices. In such a configuration having two independent operation detection devices, for example, when the system frequency deviation is near “0”, there is a variation in frequency measurement. Then, for example, it is possible to inject additional reactive power having a leading phase, and injecting reactive power having a lagging phase in the other distributed power supply apparatus. In this case, the additionally injected reactive power is offset and power fluctuation cannot be caused. As a result, the isolated operation is not detected and the isolated operation state is continued.

  The present invention has been made in view of the above, and it is possible to prevent the reactive power injected into the power system from being canceled, and to reliably detect an isolated operation even when the reactive power and the load reactive power are balanced. It is an object of the present invention to provide an isolated operation detection device, an isolated operation detection method, an isolated operation detection control device, and a distributed power supply device.

  In order to solve the above-described problems and achieve the object, the present invention detects a single operation of a distributed power supply device linked to the power system based on electrical fluctuations that occur in the power system. A control device configured to detect isolated operation, wherein the control device is configured to measure the electrical variation, and based on the measurement value measured by the measurement unit, the power controlled by the control device. Reactive current for performing control for additionally injecting reactive power of a phase preset in the power system within a first preset period when the already injected reactive power injected by the conversion means balances with the load reactive power An injection control unit, an isolated operation determination unit for determining an isolated operation based on the measurement value of the measurement unit, and the already injected reactive power and the additional injection disabled that has been additionally injected based on the calculation result of the reactive current injection unit A reactive power interference determination unit that determines whether or not the force is interfering, and the reactive power interference determination unit includes a frequency deviation at an additional injection time point when the reactive power is additionally injected within the first period. Interference between the already-injected reactive power and the additional injected reactive power is determined based on the absolute value of the difference between the value and the value of the frequency deviation at the elapse of the second period shorter than the first period. When the reactive current injection control unit determines that the determination result of the reactive power interference determination unit is interfering, the additional injection reactive power of the phase obtained by inverting the phase of the additional injection reactive power is changed again. When the control for injecting the first period is performed and it is determined that the determination result of the reactive power interference determination unit is not interfering, the remaining until the first period elapses from the injection point of the additional injection reactive power Duration, said additional injection And performing control to continue the injection of additional reactive power reactive power and phase.

  According to the present invention, it is possible to prevent the reactive power injected into the power system from being canceled and to detect the isolated operation reliably even if the reactive power and the load reactive power are balanced.

The figure which shows the structure of the distributed power supply device to which the isolated operation detection method which concerns on this Embodiment is applied. Image diagram showing an example when a large number of distributed power supply units are connected to the power system The block diagram which shows an example of a function structure of the control apparatus which concerns on this Embodiment The figure which shows the characteristic curve at the time of the reactive energy calculating part which concerns on this Embodiment calculating a reactive energy Flowchart for explaining operation in reactive power interference determination unit The figure which shows the operation waveform in case existing injection reactive power and additional reactive power interfere The figure which shows the operation waveform when existing injection reactive power and additional reactive power do not interfere

  Hereinafter, an isolated operation detection method, a control device, an isolated operation detection device, and a distributed power supply device according to embodiments of the present invention will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment.
FIG. 1 is a diagram illustrating a configuration of a distributed power supply apparatus to which an isolated operation detection method according to an embodiment of the present invention is applied. The distributed power supply device 1 according to the embodiment includes a power supply unit 5 and a power conditioner 10, and the power conditioner 10 includes an inverter 11 and an independent operation detection device 16. The operation detection device 16 includes an inverter control unit 12, a control device 13, an interconnection relay 14, and a current detector 15.

  The power supply means 5 is, for example, a solar cell or a gas engine generator, and generates DC power and supplies it to the power conditioner 10 that is power conversion means.

  The power supply means 5 is connected to the power system 2 via the power conditioner 10. The power conditioner 10 has a power conversion function for converting DC power generated by the power supply means 5 into AC power. The AC power converted by the power conditioner 10 is supplied to the power system 2 and also to the load 3 which is a general household electrical appliance, for example.

  The inverter 11 has a power conversion function in the power conditioner 10. The inverter control unit 12 controls the inverter 11 based on the output voltage of the power system 2 and the current flowing between the inverter 11 and the power system 2.

  The control device 13 includes a system voltage that is a voltage value of a voltage output from the power system 2, a harmonic distortion voltage that is a voltage of a harmonic component included in the voltage output from the power system 2, and a voltage output from the power system 2. Measure the system frequency, which is the frequency of. The control device 13 generates a control signal for on / off control of the interconnection relay 14 based on the measured system voltage, harmonic distortion voltage, and system frequency, and outputs the control signal to the interconnection relay 14. A current command value for injecting injection reactive power is generated and output to the inverter control unit 12. The injection reactive power is a term that collectively refers to the existing injection reactive power and the additional injection reactive power. The function of the control device 13 will be described in further detail as follows.

  The control device 13 calculates a system frequency deviation based on the measured system frequency and calculates reactive power to be injected into the power system based on the calculated system frequency deviation. While the calculated reactive power is injected into the power system 2, the system frequency deviation is continuously below a certain level in a period in which the system frequency deviation is set based on the measured system frequency, system voltage, and harmonic voltage distortion. There is no substantial change in the system frequency so that the state continues, and the condition that the system voltage or harmonic voltage distortion fluctuates with a change exceeding the preset fluctuation range (hereinafter referred to as “abrupt change” It is determined whether or not (referred to as “condition”) is satisfied. When the sudden change condition is satisfied, control is performed to inject additional injection reactive power in addition to the existing injection reactive power.

  FIG. 2 is an image diagram illustrating an example of a case where a large number of distributed power supply apparatuses are connected to the power system. The isolated operation detection method in the isolated operation detection device is roughly divided into an active method and a passive method, but the method of injecting reactive power as in the isolated operation detection device of the present embodiment is the active method. . In the active system, it is said that it takes 0.5 to 1.0 seconds to perform the isolated operation detection by the isolated operation detection device. On the other hand, this numerical range is a characteristic that assumes a single operation in “(1) Residential unit” that does not include the pole transformer 22 under the pole transformer 22. At the stage where distributed power supplies are in widespread use, even these numerical detection characteristics were not a problem.

  However, recently, the distributed power supply has entered the popularization period, and is in a situation where a large number of distributed power supply apparatuses are connected as shown in FIG. When a large number of distributed power supply devices are interconnected, “(2) unit on pole transformer” including the pole transformer 22, “(3) unit switch unit” including the segment switch 24, and For example, in “(4) Feeder unit” including the circuit breaker 26 provided in a substation of an electric power company, there is a possibility of an independent operation.

  Therefore, there is a demand for an isolated operation detection device and an isolated operation detection method that operate effectively even in a high voltage system such as “(2) pole transformer unit”, “(3) section switch unit” and “(4) feeder unit”. Has been. The function of the control device 13 according to the present embodiment can meet the demand for useful operation even in a high-pressure system. Hereinafter, the function of the control device 13 will be described in detail with reference to FIG.

  FIG. 3 is a block diagram illustrating an example of a functional configuration of the control device 13 according to the present embodiment. First, the control device 13 is provided with a measuring unit 30 to which a waveform signal of a voltage output from the power system 2 is input. The measurement unit 30 includes a system voltage measurement unit 131, a harmonic distortion detection unit 132, and a frequency measurement unit 133. The system voltage measurement unit 131 measures a system voltage that is a voltage value of a voltage output from the power system 2 based on the waveform signal. The harmonic distortion detector 132 measures a harmonic distortion voltage that is a voltage value of a harmonic component included in the voltage output from the power system 2 based on the waveform signal. The frequency measurement unit 133 measures a system frequency that is a frequency of a voltage output from the power system 2 based on the waveform signal.

  The isolated operation determination unit 134 determines the isolated operation from the measurement value of the frequency measurement unit 133 and generates an isolated operation detection signal that is a control signal for on / off control of the interconnection relay 14 based on the determination result. Output to the interconnection relay 14. The frequency deviation calculation unit 135 calculates a moving average value of the current system frequency and a moving average value of the past system frequency based on the measurement value of the frequency measurement unit 133, and uses each of these calculated values. Calculate system frequency deviation. The reactive power amount calculation unit 136 calculates the reactive power amount to be injected into the power system 2 using the system frequency deviation calculated by the frequency deviation calculation unit 135.

  The control device 13 further includes a reactive power injection determination unit 137. The reactive power injection determining unit 137 continuously maintains a state where the system frequency deviation is constant or lower during the second period, the system frequency is not substantially changed, and the harmonic voltage distortion or the system voltage is When a change exceeding a preset fluctuation range is made, it is determined that the harmonic voltage distortion or the system voltage has suddenly changed due to the occurrence of the isolated operation, and control for injecting additional reactive power is performed.

  The isolated operation detection signal that is the output of the isolated operation determination unit 134 and the current command value that is the output of the output current control unit 139 are the outputs of the control device 13. Again, the isolated operation detection signal is output to the interconnection relay 14, and the current command value is output to the inverter control unit 12.

  Here, it supplements about operation | movement of the frequency measurement part 133 and the frequency deviation calculating part 135. FIG.

  The frequency measurement unit 133 sequentially measures the system frequency of the power system 2 in units of measurement cycles. An example of the measurement cycle unit is, for example, a unit of 5 milliseconds. In addition, when the system frequency of the power system 2 is 50 Hz, since one system period is 20 milliseconds, the system period unit may be 1/3 or less of the system period of the power system 2, for example, 5 milliseconds unit. desirable.

  The frequency deviation calculation unit 135 sequentially calculates a moving average value for a continuous preset moving average time based on a cycle that is an integral multiple of the measurement cycle unit (5 msec unit) sequentially measured by the frequency measurement unit 133. . An example of a cycle that is an integral multiple of a measurement cycle unit (5 msec unit) is, for example, 40 msec. In addition, it is preferable that the preset moving average time is longer than 20 milliseconds which is one cycle of the system cycle, and is shorter than 100 milliseconds which is a desired detection speed, for example, 40 milliseconds. Set to.

  The control device 13 further includes an addition unit 138 and an output current control unit 139. The adding unit 138 adds the calculated reactive power from the reactive power amount calculating unit 136 and the additional reactive power from the reactive power injection determining unit 137 and outputs the result to the output current control unit 139. The output current control unit 139 performs control to output a current command value corresponding to the output of the addition unit 138 to the inverter control unit 12.

  The frequency deviation calculation unit 135, the reactive power amount calculation unit 136, the reactive power injection determination unit 137, the addition unit 138, and the output current control unit 139 described above constitute the reactive current injection control unit 32 in the control device 13.

  The control device 13 further includes a reactive power interference determination unit 140. The reactive power interference determination unit 140 performs a determination operation described later based on the system frequency deviation from the frequency deviation calculation unit 135 and the output of the reactive power injection determination unit 137, and sends the determination result to the reactive power injection determination unit 137. Output. The reactive power injection determination unit 137 generates a control signal for performing reactive power injection control according to the determination result of the reactive power interference determination unit 140, that is, the re-determination result regarding the reactive power injection.

  FIG. 4 is a diagram showing a characteristic curve when the reactive power amount calculation unit 136 calculates the reactive power amount Q, and shows the relationship of the reactive power amount Q to the system frequency deviation Δf. Note that the reactive power amount Q shown on the vertical axis corresponds to the already injected reactive power for the isolated operation detection.

  The characteristic curve shown in FIG. 4 is incorporated in the control device 13 and is referred to by the reactive energy calculation unit 136. The reactive power amount calculation unit 136 calculates a phase-advanced reactive power amount Q when the system frequency deviation Δf is positive, and calculates a phase-lag reactive power amount Q when the system frequency deviation Δf is negative. As a result, as a basic operation, when the system frequency deviation Δf is positive, the inverter control unit 12 generates a phase advance reactive power and injects it into the power system 2, and when the system frequency deviation Δf is negative, inverter control is performed. The reactive power with phase lag is generated by the unit 12 and injected into the power system 2.

  In the characteristic curve shown in FIG. 4, the change characteristic is switched at the system frequency deviation Δf1. More specifically, when the system frequency deviation Δf is small, the rate of change of the reactive power amount Q with respect to the change of the system frequency deviation Δf is reduced to reduce the reactive power amount output to the power system 2. Yes. On the other hand, when the system frequency deviation Δf is large, the rate of change of the reactive power amount Q with respect to the change of the system frequency deviation Δf is increased, and the reactive power amount Q output to the power system 2 increases. The reactive energy calculator 136 calculates the reactive energy Q based on the system frequency deviation Δf calculated by the frequency deviation calculator 135 so as to follow the characteristic curve of FIG.

  Next, reactive power injection control by the reactive power interference determination unit 140 will be described with reference to FIGS. 5 to 7. FIG. 5 is a flowchart for explaining the operation in reactive power interference determination section 140. FIG. 6 is a diagram illustrating an operation waveform when the already-injected reactive power interferes with the additional reactive power, and FIG. 7 is a diagram illustrating an operation waveform when the already-injected reactive power and the additional reactive power do not interfere with each other. is there. 6 and 7, (a) shows the system frequency deviation Δf, (b) shows the additional injection reactive power, and (c) shows the operation waveform of the already injected reactive power.

  In FIG. 5, the reactive power injection determining unit 137 determines whether to inject additional reactive power (step S1). In the determination process of step S1, as described above, it is determined whether the already injected reactive power and the load reactive power are balanced based on the system frequency deviation Δf calculated by the frequency deviation calculating unit 135. Here, when it is determined that the injected reactive power and the load reactive power are not balanced (step S1, No), the determination process of step S1 is repeated. On the other hand, if it is determined that the already injected reactive power and the load reactive power are balanced (step S1, Yes), the additional injected reactive power having a phase delay of a preset phase value is output ( Step S2).

  The injection timing by the process of step S2 is timing t0 in FIG. At timing t0, as shown in FIG. 6A, it is shown that the system frequency deviation Δf is positive, and the phase of the additional injection reactive power is a delayed phase as shown in FIG. 6B. It is shown. As described above, in the operation by the reactive power injection determining unit 137, the phase of the reactive power output from the reactive power injection determining unit 137 is set to a preset delay side phase regardless of the sign of the system frequency deviation Δf. Has been.

  The output of the reactive power injection determining unit 137 is input to the reactive power interference determining unit 140 as shown in FIG. With this configuration, the reactive power interference determination unit 140 can know the injection timing t0 of additional reactive power from the output change of the reactive power injection determination unit 137. The reactive power interference determination unit 140 controls the subsequent processing after knowing the injection timing t0. In the present embodiment, the output period of the additional injected reactive power from the reactive power injection determining unit 137 is set to three system cycles, but needless to say, the output period may not be three cycles.

  The reactive power interference determination unit 140 determines whether or not two periods have elapsed in the system cycle, which is a period before the three cycles elapse from the injection timing t0 (step S3). In FIG. 6, a period of two cycles from t0 is shown as t1. Here, if the period of two cycles has not passed (step S3, No), the determination process of step S2 is repeated. On the other hand, if the period of two cycles has passed (step S3, Yes), it will transfer to step S4.

  In step S4, first, the reactive power interference determination unit 140 is preset with an absolute value | Δft0−Δft1 | of the difference between the frequency deviation Δft1 at the determination timing t1 and the system frequency deviation Δft0 at the injection timing t0. It is determined whether it is less than the determined value. An example of the determination value is 0.5 Hz, for example. The reactive power interference determination unit 140 further determines the presence or absence of interference between the additional reactive power and the already-injected reactive power based on the determination result of whether or not it is less than the determination value.

  Further, in step S4, the reactive power interference determination unit 140 cancels the additional reactive power with the already injected reactive power if the value of | Δft0−Δft1 | is less than the determination value, for example, as illustrated in FIG. Since the additional injection reactive power is in the delayed phase, it is determined that the phase of the already injected reactive power is the leading side.

  The reactive power interference determination unit 140 changes the injection direction of the additional reactive power to the forward side in order to match the phase of the additional reactive power with the phase of the already injected reactive power based on the phase determination result of the already injected reactive power. (Step S5), a signal indicating the injection direction information changed in Step S5, that is, a signal indicating that the phase of the additional reactive power is changed to the advance side is notified to the reactive power injection determining unit 137.

  Reactive power injection determination unit 137 receives the notification from reactive power interference determination unit 140 and changes the injection direction of additional reactive power.

  The reactive power interference determination unit 140 determines whether, for example, three cycles have elapsed in the system cycle after the additional reactive power injection direction is changed (step S6). If the time for three cycles has not elapsed (step S6, No), the processing of steps S5 and S6 is repeated, and if the time for three cycles has elapsed (step S6, Yes), the time for three cycles The reactive power injection determination unit 137 is notified of a signal indicating that has passed.

  The reactive power injection determining unit 137 stops the injection of the additional reactive power in response to the signal input indicating that the time for three cycles has passed (step S9), and after the stop of the additional reactive power injection, For example, it is determined whether or not five cycles have elapsed (step S10). If the time for 5 cycles has not elapsed (step S10, No), the processing of steps S9 and S10 is repeated, and if the time for 5 cycles has elapsed (step S10, Yes), the processing of step S1 is performed. Return.

  On the other hand, in step S4, the reactive power interference determining unit 140 cancels the additional reactive power with the already injected reactive power if the value of | Δft0−Δft1 | is equal to or greater than the determination value, for example, as illustrated in FIG. It is determined that no interference has occurred (step S4, No), and a signal indicating that the injection direction of the additional reactive power is not changed is notified to the reactive power injection determination unit 137.

  The reactive power injection determination unit 137 receives the notification from the reactive power interference determination unit 140, and as shown in FIG. 7B, the reactive power injection of the delayed phase is further performed in the system cycle from the timing t1, for example, one cycle. Continue for a minute (step S7).

  The reactive power interference determination unit 140 determines whether or not the additional reactive power injection has elapsed for one cycle in the system cycle (step S8). If the time for one cycle has not elapsed (step S8, No), the processing of steps S7 and S8 is repeated, and if the time for one cycle has elapsed (step S8, Yes), the processing of step S9 is performed. Transition to stop injection of additional reactive power. Subsequent operations are as described above.

  As described above, in the present embodiment, additional reactive power is injected into the power system as already injected reactive power based on the system frequency deviation in the power system, and when this already injected reactive power balances with the load reactive power, the power Regardless of the sign of the system frequency deviation, additional reactive power, which is reactive power with a delay phase that is a predetermined phase, is additionally injected into the system as a first period, for example, for three periods in the system period. The system frequency deviation, that is, the system frequency fluctuation is an example of an electrical fluctuation that occurs in the power system. Instead of the system frequency deviation, the system voltage deviation representing the system voltage fluctuation and the harmonic component fluctuation are represented. A harmonic distortion voltage deviation may be used as a determination index.

  By the time the first period elapses, a second period that is a period shorter than the first period after the injection of the additional reactive power, for example, two periods in the system period has elapsed. Later, it is determined whether or not the additional injection reactive power is offset by the already injected reactive power. This determination is made based on the absolute value | Δft0−Δft1 | of the difference between the frequency deviation Δft1 at the determination timing t1 and the system frequency deviation Δft0 at the injection timing t0. As a result of this determination, if the value of | Δft0−Δft1 | at the determination time is less than the determination value, the phase of the already injected reactive power is opposite to the phase of the additional injected reactive power and interferes. The additional injection reactive power of the phase obtained by inverting the phase of the additional injection reactive power is injected again during the first period, so that the additional injection reactive power does not need to be offset by the existing injection reactive power, It becomes possible to detect the isolated operation by breaking the reactive power balance with the additional injection reactive power.

  If the value of | Δft0−Δft1 | at the time of the determination is larger than the determination value, it is determined that the phase of the already injected reactive power is the same as the phase of the additional injected reactive power and there is no interference. Since the injection of additional injection reactive power is continued in the same phase for the remaining period from the injection reactive power injection until the first period elapses, the reactive power balance is effectively disrupted by the additional injection reactive power. In this way, it becomes possible to reliably perform the isolated operation detection.

  In the above processing, the system frequency deviation, that is, the fluctuation of the system frequency is an example of the electrical fluctuation in the power system. Instead of the system frequency deviation, the system voltage deviation representing the fluctuation of the system voltage and the harmonic component You may use the harmonic distortion voltage deviation showing a fluctuation | variation as a determination parameter | index.

  The configurations described in the above embodiments are examples of the configurations of the present invention, and can be combined with other known techniques, and a part of the configurations is omitted without departing from the gist of the present invention. Needless to say, it may be configured.

  DESCRIPTION OF SYMBOLS 1 Distributed type power supply device, 2 Electric power system, 3 Load, 5 Power supply means, 10 Power conditioner, 11 Inverter, 12 Inverter control part, 13 Control apparatus, 14 Interconnection relay, 15 Current detector, 16 Independent operation detection apparatus , 22 pole transformer, 24 section switch, 26 circuit breaker, 30 measurement unit, 32 reactive current injection control unit, 131 system voltage measurement unit, 132 harmonic distortion detection unit, 133 frequency measurement unit, 134 isolated operation determination unit , 135 Frequency deviation calculation unit, 136 Reactive power amount calculation unit, 137 Reactive power injection determination unit, 138 Addition unit, 139 Output current control unit, 140 Reactive power interference determination unit.

Claims (8)

A control device for single operation detection configured to detect single operation of a distributed power supply device linked to the power system, based on electrical fluctuations that occur in the power system,
The controller is
A measurement unit for measuring the electrical variation;
When the already injected reactive power injected by the power conversion means controlled by the control device is balanced with the load reactive power based on the measurement value measured by the measuring unit, the phase invalid in advance set in the power system A reactive current injection control unit that performs control to additionally inject power within a preset first period;
An isolated operation determination unit that determines an isolated operation based on the measurement value of the measurement unit;
Based on the calculation result of the reactive current injection control unit, a reactive power interference determination unit that determines whether or not the already injected reactive power interferes with the additionally injected reactive power that has been additionally injected,
With
The reactive power interference determination unit includes a value of a frequency deviation at an additional injection time point when additional reactive power is additionally injected within the first period, and a frequency deviation value at a time point when a second period shorter than the first period is passed. Determining the interference between the already injected reactive power and the additional injected reactive power by the absolute value of the difference between the values,
The reactive current injection control unit includes:
When it is determined that the determination result of the reactive power interference determination unit interferes, control is performed to inject additional injection reactive power having a phase obtained by inverting the phase of the additional injection reactive power again in the first period. ,
When it is determined that the determination result of the reactive power interference determination unit does not interfere, the remaining period until the first period elapses from the time of injection of the additional injection reactive power, the same phase as the additional injection reactive power A control device that performs control to continue injection of additional reactive power.   The reactive power interference determination unit is configured such that an absolute value of a difference between a frequency deviation value after the additional reactive power injection and a frequency deviation value after a period shorter than the first period is less than a determination value It is determined that the already injected reactive power and the additional injected reactive power interfere with each other, and if it is equal to or greater than the determination value, it is determined that the already injected reactive power and the additional injected reactive power do not interfere with each other. The control device according to claim 1, wherein:   The control device according to claim 1, wherein the electrical variation is a system frequency variation, a system voltage variation, or a harmonic variation.   4. The device according to claim 1, wherein the first period is a period that is three times the system period, and the second period is a period that is twice the system period. 5. Control device.   An isolated operation detection device for detecting whether or not the distributed power supply device is isolated from the electric power system and operated independently, comprising the control device according to any one of claims 1 to 4. An isolated operation detection device.   A distributed power supply device comprising the isolated operation detection device according to claim 5. An isolated operation detection method for detecting isolated operation of a distributed power supply unit connected to the power system based on electrical fluctuations that occur in the power system,
A first step of injecting reactive power into the power system based on the electrical variation;
When the already injected reactive power injected by the first step is balanced with the load reactive power, a second phase of the additional reactive power having a preset phase in the power system is additionally injected within a preset first period. Steps,
The absolute value of the difference between the value of the frequency deviation at the time of the additional injection in the second step and the value of the frequency deviation at the time of the second period shorter than the first period, A third step of determining whether or not the additional injection reactive power additionally injected by the second step interferes;
From the determination result in the third step, when it is determined that there is interference, the fourth step of injecting the additional injection reactive power of the phase obtained by inverting the phase of the additional injection reactive power again in the first period; ,
When it is determined from the determination result in the third step that there is no interference, the remaining period from the additional injection time point in the second step until the first period elapses is injected in the second step. A fifth step of continuing to inject additional reactive power in phase with the additional injected reactive power;
An islanding operation detection method comprising:   In the determination in the third step, the absolute value of the difference between the frequency deviation value after the injection of the additional reactive power and the frequency deviation value after a period shorter than the first period is less than the determination value. In the case of the above, it is determined that the already injected reactive power and the additional injected reactive power interfere with each other, and in the case of the determination value or more, the already injected reactive power and the additional injected reactive power do not interfere with each other. The islanding operation detection method according to claim 7, wherein:

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