JP2016086574A - Control apparatus for single operation detection, and single operation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus for single operation detection capable of stopping operation of a power conditioner in the case of a power failure in a power system regardless of ripple or noise that is generated by switching an inverter.SOLUTION: The control apparatus for single operation detection comprises: a system frequency deviation calculation part 103 for calculating a system frequency deviation of a system voltage; a filter part 104 for performing filtering processing performed on the system voltage; a harmonic voltage deviation calculation part 109 for calculating a harmonic voltage deviation of a harmonic voltage included in a voltage on which the filtering processing is performed by the filter part 104; and a single operation discrimination part 110 for discriminating whether a distributed power supply device is in a single operation state by outputting reactive power to the power system if the system frequency deviation and the harmonic voltage deviation meet a condition of injecting the reactive power to the power system.SELECTED DRAWING: Figure 2

Description

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

  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 and is standardized as JEM1498 (method name: frequency feedback method with step injection) by the Japan Electrical Manufacturers' Association (JEMA).

  As one of the methods for detecting an isolated operation, Japanese Patent Application Laid-Open No. 2004-228561 has already proposed a method for injecting reactive power into an electric power system. 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.

JP 2009-136095 A

JEM1498 Frequency feedback method with step injection (standard active isolated operation detection method for power conditioners for photovoltaic power generation)

  In the independent operation detection active method defined in JEM1498, when the fundamental voltage and the harmonic voltages from the second to the seventh order satisfy a certain condition in a state where the output power of the power conditioner and the system load are balanced. It is stipulated that reactive power is injected into the system. However, the power conditioner has a built-in inverter function, and the calculation result of the fundamental voltage and the harmonic voltage may fluctuate due to the influence of ripple or noise generated by switching of the inverter. In conventional isolated operation detectors, reactive power injection operation is determined based on the values of the fundamental voltage and harmonic voltage, so if the influence of ripple or noise is large, the fundamental voltage and harmonic voltage are constant. Therefore, there is a problem that the operation of the power conditioner may continue without injecting reactive power.

  The present invention has been made in view of the above, and is a control for detecting an independent operation that can stop the operation of a power conditioner when a power failure occurs in an electric power system regardless of ripples or noise generated by switching of an inverter. The object is to obtain a device.

  In order to solve the above-described problems and achieve the object, the present invention provides a system frequency deviation calculating unit that calculates a system frequency deviation of a system voltage at a connection point between the power system and the distributed power supply device, and the system A filter unit that performs voltage filtering, a harmonic voltage deviation calculation unit that calculates a harmonic voltage deviation of a harmonic voltage included in the voltage filtered by the filter unit, the system frequency deviation, and the harmonic voltage When the deviation satisfies a condition for injecting reactive power into the electric power system, the reactive power is output to the electric power system to determine whether or not the distributed power supply is in an independent operation state And.

  According to the present invention, there is an effect that the operation of the power conditioner can be stopped at the time of a power failure of the power system regardless of the ripple or noise generated by switching of the inverter.

1 is a configuration diagram of a distributed power supply device including an isolated operation detection device and an isolated operation detection control device according to Embodiment 1 of the present invention. The figure which shows an example of the function in connection with the independent operation detection among the functions which comprise the control apparatus which concerns on Embodiment 1. Explanatory drawing of determination conditions for injecting reactive power of harmonic voltage Explanatory diagram of determination conditions for injecting reactive power of fundamental voltage The figure which shows an example of the function in connection with the independent operation detection among the functions which comprise the conventional control apparatus The figure for demonstrating the relationship between the harmonic voltage deviation calculated at the time of the interconnection operation in the conventional control apparatus, and a determination threshold value When the harmonic voltage of the same level as the determination threshold value of the determination conditions (a) and (b) is applied, the relationship between the harmonic voltage deviation calculated at the time of interconnection operation in the conventional control device and the determination threshold value will be described. Illustration for The figure for demonstrating the relationship between the harmonic voltage deviation calculated at the time of the interconnection | linkage driving | operation in the control apparatus of Embodiment 1, and a determination threshold value. When a harmonic voltage having the same level as the determination threshold value of the determination conditions (a) and (b) is applied, the relationship between the harmonic voltage deviation calculated during the interconnected operation by the control device of Embodiment 1 and the determination threshold value Illustration for explaining The figure which shows an example of the function in connection with the independent operation detection among the functions which comprise the control apparatus which concerns on Embodiment 2 of this invention. The figure which shows an example of the function in connection with the independent operation detection among the functions which comprise the control apparatus which concerns on Embodiment 3 of this invention.

  Hereinafter, a control device for isolated operation detection and an isolated operation detection device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a distributed power supply device 1 including an isolated operation detection device and an isolated operation detection control device according to the first embodiment of the present invention, and FIG. 2 is a function configuring the control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of a function related to the isolated operation detection, FIG. 3 is an explanatory diagram of determination conditions for injecting reactive power of harmonic voltage, and FIG. 4 is an explanatory diagram of conditions for injecting reactive power of fundamental voltage. is there.

  A distributed power supply apparatus 1 shown in FIG. 1 includes a power supply unit 5 that supplies generated DC power, and a power conditioner 10 that has a power conversion function that converts DC power generated by the power supply unit 5 into AC power. It is configured.

  The power supply unit 5 is a solar cell or a gas engine generator, and is connected to the power system 2 via the power conditioner 10 to generate DC power and supply it to the power conditioner 10 that is a power conversion unit. The power supply unit 5 is not limited to a solar cell or a gas engine generator, and may be a power generation means other than the solar cell or the gas engine generator, such as a wind power generator or a fuel cell.

  The power conditioner 10 is connected to the power system 2, and the AC power converted by the power conditioner 10 is supplied to the power system 2 and also to a load 3 that is a general household electrical appliance.

  The power conditioner 10 includes an inverter 11 having a power conversion function and an isolated operation detection device 16. The isolated operation detection device 16 includes an inverter control unit 12, an isolated operation detection control device 13, an interconnection relay 14, and a current detector 15 that detects a current flowing between the inverter 11 and the power system 2. It is configured. The inverter control unit 12 controls the inverter 11 based on the voltage applied to the interconnection point 17 with the power system 2 and the current detected by the current detector 15.

  FIG. 2 shows functional blocks related to the isolated operation detection among the functions of the control device 13 according to the first embodiment. The control device 13 detects a voltage at the interconnection point 17 that is a voltage output from the power system 2, and converts the waveform of the voltage detected by the system voltage detection unit 100 into a pulsed voltage signal. A voltage waveform conversion unit 101 for conversion, a system frequency measurement unit 102 for measuring a system frequency that is a frequency of a voltage output from the power system 2 based on a voltage signal from the voltage waveform conversion unit 101, and a system frequency measurement unit 102 A system frequency deviation calculation unit 103 that calculates a frequency deviation from the measured system frequency, a filter unit 104 that performs a filter process with software on the voltage detected by the system voltage detection unit 100, and a filter process performed by the filter unit 104 The fundamental wave voltage computing unit 105 that computes the fundamental wave voltage that is the fundamental wave component included in the measured voltage, and the fundamental wave voltage computing unit 105 A fundamental wave voltage deviation calculating unit 106 that calculates a fundamental wave voltage deviation using the main wave voltage, and a second to seventh harmonic voltage included in the voltage filtered by the filter unit 104 are calculated by discrete Fourier analysis. A harmonic voltage calculation unit 107, a total harmonic voltage calculation unit 108 that calculates a total value of individual harmonic voltages from the second order to the seventh order calculated by the harmonic voltage calculation unit 107, and a total harmonic voltage The harmonic voltage deviation calculating part 109 which calculates a harmonic voltage deviation using the harmonic voltage calculated by the calculating part 108, and the independent operation determination part 110 are provided.

  The harmonic voltage calculation unit 107 includes a second harmonic voltage calculation unit 107-2 that calculates a second harmonic voltage of the voltage detected by the system voltage detection unit 100, and a voltage detected by the system voltage detection unit 100. A third harmonic voltage calculator 107-3 for calculating the third harmonic voltage, a seventh harmonic voltage calculator 107-7 for calculating the seventh harmonic voltage of the voltage detected by the system voltage detector 100, and Have In FIG. 2, illustration of harmonic voltage calculation units from the 4th order to the 6th order is omitted.

The isolated operation determination unit 110 is equipped with a function of step-injecting reactive power when the following step injection condition is satisfied according to the isolated operation detection active method defined in JEM 1498.
(Step injection conditions)
(1) The system frequency deviation is within ± 0.01 Hz.
(2) The harmonic voltage deviation satisfies the condition shown in FIG. 3B, or the fundamental voltage deviation satisfies the condition shown in FIG. 4B.

In JEM 1498, specific means for calculating the harmonic voltage is not defined, but is defined as follows.
(1) The second to seventh harmonics are used for the calculation of the harmonic voltage.
(2) Discrete Fourier analysis may be used for the calculation of the harmonic voltage.

  The isolated operation determination unit 110 is calculated by the system frequency deviation calculated by the system frequency deviation calculation unit 103, the deviation of the fundamental voltage calculated by the fundamental voltage deviation calculation unit 106, and the harmonic voltage deviation calculation unit 109. Whether or not the conditions shown in FIGS. 3 and 4 are satisfied is determined based on the deviation of the harmonic voltage. When the condition is satisfied, the isolated operation determination unit 110 outputs a command for injecting reactive power for three cycles in the system cycle to the inverter control unit 12.

  At this time, if the distributed power supply device 1 is in a single operation state, the system frequency fluctuates due to the injected reactive power. When the system frequency fluctuates, the isolated operation determination unit 110 determines that the distributed power supply device 1 is in the isolated operation state, generates a relay control signal for controlling the interconnection relay 14 to be turned off, and generates the generated signal. By outputting to the interconnection relay 14, the power conditioner 10 is disconnected from the system. When it is determined that the distributed power supply device 1 is in the single operation state, the single operation determination unit 110 generates a gate block signal for stopping the inverter 11 and outputs the gate block signal to the inverter control unit 12.

  On the other hand, the injected reactive power is absorbed by the power system 2 if the distributed power supply device 1 is not in a single operation state. Therefore, when the system frequency does not vary, the isolated operation determination unit 110 determines that the distributed power supply device 1 is not in the isolated operation state, and the distributed power supply device 1 continues to operate.

  The numbers from 0 to 15 shown in FIG. 3A represent the system periods sequentially measured by the harmonic voltage calculation unit 107. Specifically, 0 is the current system cycle, and 1 to 15 are system cycles measured before i (i is a natural number from 1 to 15) cycles. N0 is a harmonic voltage effective value obtained by summing up the second to seventh harmonic voltages calculated in the current system cycle. Similarly, N1 to N5 are harmonic voltage effective values obtained by summing up the second to seventh harmonic voltages calculated in the system cycle before i cycles. Navr is a harmonic voltage effective value for three cycles of a harmonic voltage effective value N3 three cycles before the present, a harmonic voltage effective value N4 four cycles before, and a harmonic voltage effective value N5 five cycles before. Average value. The average value Navr of the harmonic voltage effective value is calculated by the harmonic voltage deviation calculating unit 109.

  FIG. 3B shows six conditions for injecting the reactive power of the harmonic voltage defined by JEM1498. In the condition (a), the condition is satisfied when the harmonic voltage deviation, which is the difference between the harmonic voltage effective value N0 and the average value Navr, is larger than a predetermined determination threshold, for example, 2 volts. According to the condition (b), the condition is satisfied when the harmonic voltage deviation, which is the difference between the harmonic voltage effective value N1 and the average value Navr, is larger than a predetermined determination threshold, for example, 2 volts. According to the condition (c), the condition is satisfied when the harmonic voltage deviation, which is the difference between the harmonic voltage effective value N2 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts. To do. According to the condition (d), the harmonic voltage deviation, which is the difference between the harmonic voltage effective value N3 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met. According to the condition (e), the harmonic voltage deviation which is the difference between the harmonic voltage effective value N4 and the average value Navr is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met. According to the condition (f), the harmonic voltage deviation which is the difference between the harmonic voltage effective value N5 and the average value Navr is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met.

  The numbers from 0 to 13 shown in FIG. 4A represent the system periods sequentially measured by the fundamental voltage calculator 105. Specifically, 0 is the current system cycle, and 1 to 15 are system cycles measured before i (i is a natural number from 1 to 15) cycles. N0 is the fundamental voltage effective value calculated in the current system cycle. Similarly, N1 to N5 are fundamental wave voltage effective values calculated in the system cycle before i cycles. Navr is a fundamental voltage effective value for three cycles of a fundamental wave voltage effective value N3 three cycles before the present, a fundamental wave effective value N4 four cycles before, and a fundamental voltage effective value N5 five cycles before. Average value. The average value Navr of the fundamental wave voltage effective value is calculated by the fundamental wave voltage deviation calculation unit 106.

  FIG. 4B shows six conditions for injecting the reactive power of the fundamental wave voltage defined by JEM 1498. In the condition (a), the condition is satisfied when a fundamental wave voltage deviation, which is a difference between the fundamental wave voltage effective value N0 and the average value Navr, is larger than a predetermined determination threshold, for example, 2.5 volts. According to the condition (b), the condition is satisfied when the fundamental voltage deviation, which is the difference between the fundamental voltage effective value N1 and the average value Navr, is larger than a predetermined determination threshold, for example, 2.5 volts. . According to the condition (c), the condition is satisfied when the fundamental voltage deviation, which is the difference between the fundamental voltage effective value N2 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts. To do. According to the condition (d), the fundamental voltage deviation, which is the difference between the fundamental voltage effective value N3 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met. According to the condition (e), the fundamental voltage deviation, which is the difference between the fundamental voltage effective value N4 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met. According to the condition (f), the fundamental voltage deviation, which is the difference between the fundamental voltage effective value N5 and the average value Navr, is larger than a predetermined determination threshold, for example, −0.5 volts, and 0.5 If it is smaller than the bolt, the condition is met.

  FIG. 5 is a diagram showing an example of a function related to the isolated operation detection among the functions constituting the conventional control device. In the control device 130 shown in FIG. 5, the filter unit 104 of FIG. 2 is not provided. This is different from the control device 13 of the first embodiment.

  FIG. 6 is a diagram for explaining the relationship between the harmonic voltage deviation calculated during the linked operation in the conventional control device and the determination threshold. In FIG. 6, the waveform of the system voltage, the calculation timing of the harmonic voltage in the harmonic voltage deviation calculation unit 109, the determination thresholds of the determination conditions (d) to (f) set in the isolated operation determination unit 110, The harmonic voltage deviation calculated by the harmonic voltage deviation calculating unit 109 is shown. The solid line in the figure represents the value of the harmonic voltage deviation calculated by the harmonic voltage deviation calculating unit 109, and the shaded portion is -0.5 of the dotted line that is the determination threshold value of the determination conditions (d) to (f). Represents a range from volt to 0.5 volt.

  FIG. 7 shows the relationship between the harmonic voltage deviation calculated at the time of interconnection operation in the conventional control device and the determination threshold when a harmonic voltage of the same level as the determination threshold of the determination conditions (a) and (b) is applied. It is a figure for demonstrating. FIG. 7 shows the waveform of the system voltage and the calculation timing of the harmonic voltage in the harmonic voltage deviation calculation unit 109, as in FIG. Reference numerals (a) to (e) shown in FIG. 7 correspond to the determination conditions (a) to (e) shown in FIG. 3 (b). Of the solid lines in the figure, the solid line shown at the top of (a) represents the harmonic voltage deviation between the harmonic voltage effective value N0 calculated by the harmonic voltage deviation calculating unit 109 and the average value Navr of the harmonic voltage. . Similarly, the solid line shown at the top of (b) is the harmonic voltage deviation between N1 and Navr, the solid line shown at the top of (c) is the harmonic voltage deviation between N2 and Navr, and the solid line at the top of (d) is The harmonic voltage deviation between N3 and Navr, and the solid line shown at the top of (e) represents the harmonic voltage deviation between N4 and the average value Navr. Among the shaded portions shown in the upper part of (a) to (e), the portions corresponding to (a) and (b) are the dotted 2.0 volts that is the determination threshold value of the determination conditions (a) and (b). The part corresponding to (c) represents the above range, and the part corresponding to (d) and (e) Represents a range from -0.5 volts to 0.5 volts of a dotted line, which is a determination threshold value of the determination conditions (d) and (e).

In the control device 130 shown in FIG. 5, as in the control device 13 of the first embodiment, it is determined whether the system frequency deviation, the fundamental voltage deviation, and the harmonic voltage deviation satisfy the following conditions.
(Step injection conditions)
(1) The system frequency deviation is within ± 0.01 Hz.
(2) The harmonic voltage deviation satisfies the condition shown in FIG. 3B, or the fundamental voltage deviation satisfies the condition shown in FIG. 4B.

  When the condition is satisfied, the isolated operation determination unit 110 of the control device 130 outputs a command for injecting reactive power to the inverter control unit 12. At this time, if the distributed power supply 1 is in the single operation state, the system frequency is changed by the injected reactive power, and therefore it is detected that the distributed power supply device 1 is in the single operation state. On the other hand, if the distributed power supply device 1 is not in the single operation state, the injected reactive power is absorbed by the power system 2 and the system frequency does not fluctuate.

  Here, since the output voltage of the inverter 11 includes a ripple or noise due to switching, when the harmonic voltage is calculated in a state where the ripple or noise is included, the distributed power supply device 1 operates in an interconnected manner. In spite of being inside, the harmonic voltage deviation may fluctuate as shown by the solid line in FIG. In this way, when the distributed power supply 1 fluctuates during the grid operation, and the harmonic voltage deviation deviates from the determination threshold value (f) from the determination condition (d), the distributed power supply device 1 thereafter When the power supply device 1 enters the single operation state, the harmonic voltage increases rapidly, and even if the harmonic voltage deviation satisfies the determination conditions (a) to (c), the determination conditions (d) to (f) are not satisfied. For this reason, even when the distributed power supply device 1 is in an isolated operation state, reactive power is not injected and the isolated operation cannot be detected, or the time until the isolated operation is detected may be long.

  Further, when the harmonic voltage increases due to the ripple or noise caused by switching, the average value Navr shown in FIG. 3A also increases. Even when the distributed power supply 1 is not in a single operation state, even if the harmonic voltage deviations shown in (d) and (e) of FIG. 7 satisfy the determination conditions (d) and (e) shown in FIG. When the harmonic voltage of the same level as the determination threshold value 2.0 volts of the determination conditions (a) and (b) is applied after the distributed power supply device 1 enters the single operation state, FIG. The harmonic voltage deviation between N0 and Navr and the harmonic voltage deviation between N1 and Navr shown in FIGS. 7 (a) and 7 (b) are judged conditions (a), (b ) May be below the determination threshold. Therefore, even when the distributed power supply device 1 enters the single operation state, reactive power is not injected, and the single operation detection cannot be performed, or the time until the single operation detection may be long.

  On the other hand, the control device 13 according to the first embodiment uses the filter unit 104 in FIG. 2 to display the measured system voltage by software in order to prevent an increase in harmonic voltage due to ripple or noise caused by driving the inverter 11. The filter process is executed, and the fundamental voltage and the harmonic voltage are calculated using the values. As the characteristics of the filter used here, JEM 1498 requires that harmonic voltages from the second order to the seventh order be measured, and when the system frequency is 60 Hz, the seventh order harmonic component is 420 Hz. The cut-off frequency is preferably set to a value larger than 420 Hz. When the system frequency is 50 Hz, the seventh harmonic component is 350 Hz, so the cutoff frequency is preferably set to a value larger than 350 Hz.

  FIG. 8 is a diagram for explaining the relationship between the harmonic voltage deviation calculated during the grid operation in the control device of the first embodiment and the determination threshold value. FIG. 8 shows the waveform of the system voltage, the calculation timing of the harmonic voltage, the determination threshold values of the determination conditions (d) to (f), and the harmonic voltage deviation, as in FIG. The difference from FIG. 6 is that the fundamental voltage and the harmonic voltage are calculated from the filtered voltage value, so that the harmonic voltage deviation indicated by the solid line is determined from the determination conditions (d) to (f). This is a point that falls within the range of −0.5 volts to 0.5 volts. In the control device 13 according to the first embodiment, the fundamental wave voltage and the harmonic voltage are calculated using the filtered voltage value, so that the influence of ripple or noise due to switching is reduced when the fundamental wave voltage and the harmonic voltage are calculated. be able to. Accordingly, the fluctuation of the harmonic voltage deviation during the interconnection operation is reduced, and the effective value of the harmonic voltage during the interconnection operation is almost zero. As a result, the determination accuracy of the reactive power step injection can be improved.

  FIG. 9 shows a harmonic voltage deviation and a determination threshold value that are calculated at the time of interconnection operation in the control device of the first embodiment when a harmonic voltage of the same level as the determination threshold values of the determination conditions (a) and (b) is applied. It is a figure for demonstrating the relationship. FIG. 9 shows the waveform of the system voltage, the calculation timing of the harmonic voltage, the determination threshold value corresponding to the determination conditions (a) to (e), and the harmonic voltage deviation, as in FIG. Yes. The difference from FIG. 7 is that the fundamental voltage and the harmonic voltage are calculated from the filtered voltage value, and the harmonic voltage deviation indicated by the solid line is determined in the determination conditions (a) and (b). The threshold is 2.0 volts or more. In the control device 13 of the first embodiment, the fundamental voltage and the harmonic voltage are calculated with the filtered voltage value, so that the fluctuation of the harmonic voltage deviation during the interconnection operation is reduced, and the fluctuation of the average value Navr. Is also suppressed. As a result, the determination accuracy of the reactive power step injection can be improved.

  Note that the functions related to the isolated operation detection described in the first embodiment can be realized by changing the software of the control device used in the existing power conditioner 10 without adding a new circuit.

Embodiment 2. FIG.
FIG. 10 is a diagram illustrating an example of a function related to the isolated operation detection among the functions constituting the control device according to the second embodiment of the present invention. Hereinafter, the same reference numerals are given to the same parts as those in the first embodiment, and the description thereof is omitted, and only different parts will be described here. The difference from the first embodiment is that the filter unit 104 includes a first filter unit 104-1 corresponding to the fundamental voltage calculator 105 and a second filter unit corresponding to the second harmonic voltage calculator 107-2. Filter unit 104-2, third filter unit 104-3 corresponding to third harmonic voltage calculator 107-3, and fourth filter unit 104- corresponding to seventh harmonic voltage calculator 107-7 7. In FIG. 10, the harmonic voltage calculation units from the 4th order to the 6th order are not shown. Further, in FIG. 10, the illustration of the filter unit corresponding to the fourth to sixth harmonic voltage calculation units is omitted. As described above, the control device 13-1 of the second embodiment uses a filter suitable for each frequency when calculating the fundamental voltage and the second to seventh harmonic voltages.

  For example, when the system frequency is 60 Hz, the cutoff frequencies at the time of calculating the harmonic voltages from the second to the seventh are 150 Hz, 210 Hz, 270 Hz, 330 Hz, 390 Hz, and 450 Hz. Although the operation is the same as in the first embodiment, it is possible to effectively reduce the influence of the ripple voltage and noise component by using a filter suitable for each frequency, and further improve the determination accuracy. it can.

Embodiment 3 FIG.
FIG. 11 is a diagram illustrating an example of a function related to the isolated operation detection among the functions constituting the control device according to the third embodiment of the present invention. Hereinafter, the same reference numerals are given to the same parts as those in the first embodiment, and the description thereof is omitted, and only different parts will be described here. The difference from the first embodiment is that the voltage calculation unit 120 is used instead of the harmonic voltage calculation unit 107, and the calculation result of the fundamental wave voltage calculation unit 105 and the calculation result of the voltage calculation unit 120 are the total harmonic voltage. The total harmonic voltage calculation unit 108, which is input to the calculation unit 108, calculates the total value of the individual harmonic voltages from the second order to the seventh order by obtaining the difference between the two calculation results.

  In the third embodiment, for example, when calculating harmonic voltages from the second order to the seventh order, the characteristic of the cutoff frequency of the filter unit 104 is an intermediate frequency between the seventh order and the eighth order, that is, when the system frequency is 50 Hz. Is set to 450 Hz when the system frequency is 60 Hz. As a result, the voltage calculation unit 120 calculates a voltage obtained by removing the harmonic voltage of the 8th or higher frequency. The total harmonic voltage calculation unit 108 removes the fundamental wave voltage calculated by the fundamental wave voltage calculation unit 105 from the voltage calculated by the voltage calculation unit 120, so that total harmonic voltages from the second to the seventh order are obtained. Is calculated. According to the control device 13-2 of the third embodiment, the discrete Fourier analysis that requires software processing time can be eliminated in the harmonic voltage calculation unit 107 of the first embodiment.

  In the third embodiment, it is necessary to change the filter characteristics depending on whether the system frequency is 50 Hz or 60 Hz. However, when system interconnection is performed, the value of the system frequency is known and is implemented by software. It is very easy to change the characteristics when doing so.

  In Embodiments 1 to 3, it is possible to improve reactive power injection determination accuracy even when the harmonic voltage fluctuates or the harmonic voltage deviation fluctuates due to the ripple or noise caused by switching. As described above, the same effect can be obtained even when the fundamental wave voltage fluctuates or the fundamental wave deviation fluctuates.

  As described above, the control device for detecting an isolated operation according to the first to third embodiments includes the system frequency deviation calculation unit, the filter unit, and the harmonic voltage included in the voltage filtered by the filter unit. When the harmonic voltage deviation calculator that calculates the wave voltage deviation, the system frequency deviation and the harmonic voltage deviation satisfy the conditions for injecting reactive power into the power system, the reactive power is output to the power system and distributed. A single operation determination unit that determines whether or not the power supply device is in a single operation state. With this configuration, the harmonic voltage is calculated with the filtered voltage value, so fluctuations in the calculation result of the fundamental voltage or harmonic voltage due to ripples or noise generated by inverter switching are reduced, and the reactive power step Injection determination accuracy can be improved, and step injection of reactive power can be reliably performed. As a result, it is possible to stop the operation of the power conditioner during a power outage regardless of the ripple or noise generated by the inverter switching. Safety can be ensured.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Distributed type power supply device, 2 Power system, 3 Load, 5 Power supply part, 10 Power conditioner, 11 Inverter, 12 Inverter control part, 13, 13-1, 13-2 Control apparatus, 14 Interconnection relay, 15 Current Detector, 16 islanding detection device, 17 interconnection point, 100 system voltage detection unit, 101 voltage waveform conversion unit, 102 system frequency measurement unit, 103 system frequency deviation calculation unit, 104 filter unit, 104-1 first filter Unit, 104-2 second filter unit, 104-3 third filter unit, 104-4 fourth filter unit, 105 fundamental wave voltage calculation unit, 106 fundamental wave voltage deviation calculation unit, 107 harmonic voltage calculation unit 107-2 Second harmonic voltage calculation unit, 107-3 Third harmonic voltage calculation unit, 107-7 Seventh harmonic voltage calculation unit, 108 Total harmonic Voltage calculation unit, 109 harmonic voltage deviation calculation unit, 110 isolated operation determination unit 120 voltage calculating unit, 130 controller.

Claims (7)

A system frequency deviation calculating unit that calculates the system frequency deviation of the system voltage at the connection point between the power system and the distributed power supply device;
A filter unit for filtering the system voltage;
A harmonic voltage deviation calculating unit for calculating a harmonic voltage deviation of the harmonic voltage included in the voltage filtered by the filter unit;
When the system frequency deviation and the harmonic voltage deviation satisfy a condition for injecting reactive power into the power system, is the reactive power output to the power system and is the distributed power supply device in a single operation state? An independent operation determination unit for determining whether or not,
A control device for detecting an isolated operation, comprising: A fundamental wave voltage deviation calculating unit for calculating a fundamental wave voltage deviation of a fundamental wave voltage included in the voltage filtered by the filter unit;
The isolated operation determination unit outputs reactive power to the power system when the system frequency deviation and the fundamental voltage deviation satisfy a condition for injecting reactive power into the power system, and the distributed power supply device It is determined whether it is a single operation state, The control apparatus for single operation detection of Claim 1 characterized by the above-mentioned.   The said filter part is divided into the several filter part used for the calculation of the said harmonic voltage of several orders, The control apparatus for isolated operation detection of Claim 1 or Claim 2 characterized by the above-mentioned.   3. The filter unit according to claim 2, wherein the filter unit is divided into a filter unit used for the calculation unit of the fundamental voltage and a plurality of filter units used for calculation of the harmonic voltages of a plurality of orders. Control device for isolated operation detection. A total harmonic voltage calculation unit that calculates a total harmonic voltage obtained by summing the harmonic voltages of a plurality of orders included in the voltage filtered by the filter unit;
The said harmonic voltage deviation calculating part calculates the said harmonic voltage deviation using the said total harmonic voltage, The point for independent operation detection of any one of Claim 1 to 4 characterized by the above-mentioned. Control device.   The total harmonic voltage calculation unit calculates the total harmonic voltage from a difference between a fundamental wave voltage included in the voltage filtered by the filter unit and a voltage filtered by the filter unit. The control device for detecting an isolated operation according to claim 5, wherein:   An isolated operation detection device comprising the isolated operation detection control device according to any one of claims 1 to 6.

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