JP4552913B2 - Isolated operation detection device - Google Patents

Description

  The present invention relates to a reactive power injection circuit that injects reactive power between a distributed power source and a commercial system, a frequency fluctuation detection circuit that detects a frequency fluctuation of the reactive power injected by the reactive power injection circuit, and the frequency fluctuation. The present invention relates to an isolated operation detection device having an isolated operation detection circuit for detecting isolated operation of the distributed power source based on the frequency fluctuation detected by a detection circuit.

  Conventionally, such an isolated operation detection device includes an inverter circuit that converts DC power of a distributed power source into AC power of a commercial system, and supplies the converted AC power to a load connected to the commercial system. The inverter output waveform of this inverter circuit is distorted to produce fluctuations in the output frequency during single operation, and the single operation is detected by detecting the frequency fluctuation caused by this distortion or the fluctuation caused by the frequency fluctuation. It is known (see, for example, Patent Document 1).

  Further, according to the isolated operation detection device of Patent Document 1, in order to keep the system voltage and system frequency constant on the commercial system side, the amount of power generated by the power station on the commercial system side according to the load fluctuation of the consumer. However, when this low-frequency fluctuation occurs, a small frequency change (deviation amount change) occurs, so reactive power is injected between the distributed power supply and the commercial system. Since the dead zone range is set so as not to occur, it is possible to reliably prevent erroneous detection of isolated operation of the distributed power source due to the occurrence of low-cycle fluctuations.

  Further, according to the conventional isolated operation detection device, the isolated operation detection time from the isolated operation occurrence to the isolated operation detection requires 0.5 seconds to 1.0 seconds. For example, a high-speed detection technique that shortens within 0.1 seconds is desired.

Therefore, in order to meet such a demand, the present applicant has devised an isolated operation detection device that detects an isolated operation of a distributed power source at a high speed with an isolated operation detection time within 0.1 seconds (for example, a patent). Reference 2).
Japanese Patent Laid-Open No. 9-322554 (see paragraph numbers “0043” to “0083” and FIGS. 1 and 12) Japanese Patent Application No. 2006-6108 (see abstract and figure 2)

  However, according to the isolated operation detection device of Patent Document 2, in order to inject reactive power suitable for high-speed detection of isolated operation of a distributed power source, for example, when a commercial system is 50 Hz, a system period corresponding to 20 milliseconds is set to 20 m. Sequentially measured in seconds, based on these sequentially measured system cycles in units of 20 milliseconds, the moving average value of the system cycle for a continuous predetermined moving average time is calculated sequentially, and the latest moving average value and past moving average value Assuming that the amount of deviation is calculated and the amount of reactive power is calculated based on this amount of deviation, the following problems can be assumed.

  For example, when a system period corresponding to 20 milliseconds is sequentially measured in units of 20 milliseconds, and the moving average value is calculated in the system period of 20 milliseconds unit which is sequentially measured, as shown in FIG. If the reactive power amount of reactive power to be injected in order to detect a single operation of the distributed power source at a high speed is increased, it is supplied to the reactive power injection device (inverter circuit). A sudden change in the current waveform occurs, and there is concern about the impact on the grid.

  In addition, the moving average value is calculated based on the system cycle for a predetermined moving average time, and within the predetermined moving average time, as shown in FIG. When the single operation state B is included, the system period for the predetermined movement average time sequentially measured is averaged even though the predetermined movement average time is too long and the single operation state of the distributed power source is generated. If the fluctuation of the moving average value becomes small, it becomes difficult to separate the single operation and the normal operation. On the other hand, as shown in FIG. 5 (b), if the predetermined moving average time is too short, the frequency of the system will be averaged for the predetermined moving average time sequentially measured when the frequency fluctuation occurs at the time of isolated operation. When the fluctuation of the moving average value is small, it is difficult to separate during the single operation, and as a result, high-speed detection of the single operation cannot be realized.

  Further, the deviation amount that is the basis of the reactive power amount is calculated based on the latest moving average value and the past moving average value after a predetermined time from the latest moving average value. After that, within a predetermined time, as shown in FIG. 4 (b), when the A state during the normal operation includes the B of the single operation state of the distributed power source, the single operation state of the distributed power source has occurred. Nevertheless, since the fluctuation of the moving average value is small, no deviation occurs, and as a result, high-speed detection of an isolated operation cannot be realized.

  Further, according to the isolated operation detection device of Patent Document 1, as shown in FIG. 6B, within the dead band range (X1 to X2) where the frequency fluctuation (deviation amount) is small, between the distributed power source and the commercial system. Since reactive power is not injected, even if a single operation of the distributed power source occurs, it is not possible to detect the single operation of the distributed power source within the dead band range where the frequency fluctuation is small.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an isolated operation detection device capable of realizing high-speed injection of reactive power suitable for detecting an isolated operation of a distributed power source at high speed. There is.

  In addition, an object of the present invention is to inject reactive power at high speed between the distributed power source and the commercial system in order to detect the single operation of the distributed power source at high speed even in the dead zone range where the deviation amount is small. An object of the present invention is to provide an isolated operation detection device capable of

  In order to achieve the above object, the isolated operation detection device of the present invention includes a reactive power injection circuit for injecting reactive power between a distributed power source and a commercial system, and a frequency variation of the reactive power injected by the reactive power injection circuit. A single operation detection device comprising: a frequency fluctuation detection circuit for detecting a single operation detection circuit for detecting a single operation of the distributed power source based on the frequency fluctuation detected by the frequency fluctuation detection circuit, The system cycle measuring means for measuring the system cycle of the commercial system in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system, and the system cycle of the measurement cycle unit sequentially measured by the system cycle measuring means Based on the moving average value calculating means for sequentially calculating the moving average value of the system period for the continuous predetermined moving average time, and the moving average value sequentially calculated by the moving average value calculating means The stored moving average value storage means, the latest moving average value stored in the moving average value storage means, and the past moving average value of a predetermined time before from the latest moving average value, are read, and the latest Deviation amount calculating means for calculating a deviation amount of the moving average value and the past moving average value for each system cycle of the measurement cycle unit, and the reactive power injection circuit based on the deviation amount calculated by the deviation amount calculating means And reactive power amount calculating means for calculating the reactive power amount of the reactive power injected in step (b).

  Therefore, according to the isolated operation detection device of the present invention, the system cycle of the commercial system is sequentially measured in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system, and the measurement cycle unit that is sequentially measured. Based on the system cycle, the moving average value of the system cycle for a continuous predetermined moving average time is sequentially calculated, the sequentially calculated moving average value is sequentially stored, and the latest moving average value stored in the memory and the latest The past moving average value of a predetermined time before is read out from the moving average value of, the latest moving average value read out and the deviation amount of the past moving average value are calculated, and the reactive power injection is based on the calculated deviation amount Since the reactive power amount of the reactive power injected by the circuit is calculated, the deviation amount for calculating the reactive power amount in the system cycle of the measurement cycle corresponding to 1/3 or less of the system cycle of the commercial system of By calculating the basic moving average value, fine fluctuations of the moving average value, that is, fluctuations in the deviation amount can be smoothed, so the reactive power to be injected between the distributed power source and the commercial power system is invalid. Even if the amount of power is increased, it is possible to prevent a sudden change in the current waveform supplied to the reactive power injection device, and as a result, high speed reactive power suitable for detecting single operation of the distributed power source at high speed. Injection can be achieved.

  Further, the reactive power amount calculating means of the isolated operation detecting device of the present invention presets a dead band range where the deviation amount is small, and the deviation amount calculated by the deviation amount calculating means is within the dead band range, The reactive power amount may be calculated by correcting the absolute value of the reactive power amount of the reactive power injected by the reactive power injection circuit to be smaller than that when the deviation amount is outside the dead zone range. good.

  Therefore, according to the isolated operation detection device of the present invention, when the dead zone range in which the deviation amount is small is set in advance, and the deviation amount calculated by the deviation amount calculation means is within the dead zone range, the deviation amount is large. Since the reactive power amount is calculated by correcting the absolute value of the reactive power amount of the reactive power injected by the reactive power injection circuit to be smaller than that in the case of the sensitive band range other than the dead zone range, Even if the deviation amount is within a small dead band range, the reactive power can be injected in order to detect isolated operation of the distributed power source. Furthermore, the absolute value of the reactive power amount, that is, the injection amount By making the absolute value smaller than the sensitive band range where the deviation amount is large, the reactive power injection in the dead band range where the deviation amount is small without being affected by the slow fluctuation of the frequency on the system voltage side. No lap It is possible to reliably prevent erroneous detection of the islanding operation due to several variations.

  Moreover, you may make the said measurement period unit of the isolated operation detection apparatus of this invention into 5 msec unit which is 1/3 or less of the system period of the said commercial system.

  Therefore, according to the isolated operation detection device of the present invention, the system cycle of the commercial system is sequentially measured in units of 5 milliseconds, so the deviation amount for calculating the reactive power amount in the system period in units of 5 milliseconds. By calculating the above-mentioned moving average value that is the basis, it is possible to smooth out fine fluctuations of the moving average value, that is, deviation amount deviations, so reactive power of reactive power to be injected between the distributed power source and the commercial system Even if the amount is increased, it is possible to prevent a sudden change in the current waveform supplied to the reactive power injection device. As a result, for example, the invalidity suitable for detecting a single operation of a distributed power source at high speed in about 100 milliseconds. High speed injection of power can be realized.

  Further, the predetermined moving average time of the isolated operation detection device of the present invention is longer than the system cycle of the commercial system and is a time that allows the isolated operation detection circuit to detect the isolated operation at a high speed. It can be divided.

  Therefore, according to the isolated operation detection device of the present invention, the moving average value of the continuous 40 msec system cycle is sequentially calculated based on the system cycle sequentially measured in 5 msec units. In consideration of the time required for the calculation process, the predetermined moving average time is set to 40 milliseconds, so that the isolated operation of the distributed power source can be detected at high speed in about 100 milliseconds, for example.

  The past moving average value before the predetermined time of the isolated operation detection device of the present invention is a time enabling high-speed detection of the isolated operation of the isolated operation detection circuit, 200 ms before the latest moving average value. The past moving average value may be used.

  Therefore, according to the isolated operation detection device of the present invention, the latest moving average value stored in the moving average value storage means and the past moving average value 200 msec before the latest moving average value are read and read. Since the deviation amount of the latest moving average value and the past moving average value 200 msec before is calculated for each system cycle in 5 msec units, the past moving average value is calculated 200 msec before the latest moving average value. By using the moving average value of, it is easy to separate during normal operation and normal operation, as well as to reliably recognize frequency disturbances when a power failure occurs in commercial systems. Even if the reactive power amount of the reactive power to be injected between the power source and the commercial system is increased, it is possible to prevent a sudden change in the current waveform supplied to the reactive power injection device. The independent operation of the dispersed type power supply it is possible to realize high-speed injection of the reactive power that is suitable for detecting high speed.

  According to the isolated operation detecting device of the present invention configured as described above, the system cycle of the commercial system is sequentially measured in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system, and this sequential measurement is performed. Based on the system cycle of the measurement cycle unit, the moving average value of the system cycle for a continuous predetermined moving average time is sequentially calculated, the sequentially calculated moving average value is sequentially stored, and the latest moving average in the storage The previous moving average value of a predetermined time ago is read from the value and the latest moving average value, and the deviation amount of the read latest moving average value and the past moving average value is calculated, and based on the calculated deviation amount Since the reactive power amount of the reactive power injected by the reactive power injection circuit is calculated, the reactive power amount at a system cycle in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system. Calculate By calculating the moving average value that is the basis for the amount of deviation to be performed, it is possible to smooth the fluctuation of the moving average value, that is, the fluctuation of the deviation amount. Even if the reactive power amount of the power is increased, it is possible to prevent a sudden change in the current waveform supplied to the reactive power injection device, and as a result, the invalidity suitable for detecting single operation of the distributed power source at high speed. High speed injection of power can be realized.

  Hereinafter, a distributed power supply system showing an embodiment of an isolated operation detection device of the present invention will be described based on the drawings. FIG. 1 is a block diagram showing a schematic configuration inside a distributed power supply system according to the present embodiment.

  A distributed power system 1 shown in FIG. 1 generates direct-current power, for example, a distributed power source 2 such as a solar power generator or a gas engine generator, and a commercial system 3 connected to the distributed power source 2. A power conditioner device 4 disposed between the distributed power source 2 and the commercial system 3 and having a power conversion function, and a distributed power source 2 disposed between the power conditioner device 4 and the commercial system 3 in the event of a power failure at the commercial system 3 The power conditioner device 4 converts the DC power generated by the distributed power source 2 into the AC power of the commercial system 3 through the power conversion function. The converted AC power is supplied to a load 6 such as a general household electrical appliance.

  The isolated operation detection device 5 includes an inverter circuit 11 that injects reactive power between the distributed power source 2 and the commercial system 3, a filter circuit 12 that cuts high-frequency components of reactive power from the inverter circuit 11, and a system of the commercial system 3. A voltage detection circuit 13 for detecting the voltage, and a frequency fluctuation of the reactive power injected by the inverter circuit 11 through the voltage detection circuit 13 is detected between the distributed power source 2 and the commercial system 3, and based on this frequency fluctuation, a commercial system 3 power failure Independent operation injection circuit (invalid amount of reactive power) of inverter circuit 11 based on frequency variation of reactive power detected between distributed power source 2 and commercial system 3 The inverter drive control circuit 15 for controlling the inverter circuit 11 based on the calculated injection amount, the distributed power source 2 and the commercial system 3 The interconnection relay circuit 16 that cuts off the interconnection connection of the power source, the line between the distributed power source 2 and the commercial system 3, and the relay circuit 17 that cuts off the connection between the inverter circuits 11 and the entire independent operation detection device 5 are controlled. And a control circuit 18.

  The filter circuit 12 includes a reactor 12A and a capacitor 12B, and cuts high frequency components of reactive power injected by the inverter circuit 11.

  The inverter drive control circuit 15 includes a frequency measurement unit 21 that sequentially measures the system cycle of the commercial system 3 from the system voltage detected through the voltage detection circuit 13 in units of measurement cycles, and a measurement cycle unit that is sequentially measured by the frequency measurement unit 21. Based on the system cycle, a moving average value calculation unit 22 that sequentially calculates a moving average value of a system cycle for a continuous predetermined moving average time, and a moving average that sequentially stores the moving average value in the moving average value calculation unit 22 The value storage unit 23, the latest moving average value stored in the moving average value storage unit 23, and the past moving average value a predetermined time ago from the latest moving average value are read out, and the read out latest moving average And a deviation amount calculation unit 24 that calculates a deviation amount of a moving average value in the past and a system cycle of a measurement cycle unit, and a gain that adjusts the gain of the deviation amount calculated by the deviation amount calculation unit 24 25, a limiter unit 26 that suppresses the gain adjustment-adjusted deviation amount to a predetermined input range, and a periodic reactive power amount from the periodic variation unit 27 is corrected based on the deviation amount suppressed by the limiter unit 26, and the inverter circuit 11 The reactive power amount calculation unit 28 that calculates the reactive power amount of the reactive power injected in step S3, and the output current that controls the output current that drives the inverter circuit 11 based on the reactive power amount calculated by the reactive power amount calculation unit 28 And a control unit 29.

  The frequency measuring unit 21 sequentially measures the system period of the commercial system 3 from the system voltage through the voltage detection circuit 13 in units of measurement periods, for example, 5 milliseconds. In addition, when the system period of the commercial system 3 is 50 Hz (one system period is 20 milliseconds), the measurement period unit is desirably 1/3 or less of the system period of the commercial system 3, for example, 5 milliseconds unit.

  The moving average value calculation unit 22 sequentially calculates the moving average value of the system cycle for a predetermined predetermined moving average time, for example, 40 msec, based on the system cycle of 5 msec units sequentially measured by the frequency measurement unit 21. It is. The predetermined moving average time is preferably set to 40 ms, for example, because it is longer than one cycle of the system cycle, for example, 20 ms and as short as possible for a desired detection speed, for example, 100 ms.

  The deviation amount calculation unit 24 reads out the latest moving average value stored in the moving average value storage unit 23 and the past moving average value of a predetermined time before, for example, 200 msec from the latest moving average value. The deviation amount between the latest moving average value and the past moving average value is calculated for each system cycle in units of 5 milliseconds. Note that the past moving average value before the predetermined time is preferably set to, for example, 200 milliseconds because it is longer than the desired detection speed, for example, 100 milliseconds and is as short as possible.

  FIG. 2 is an operation explanatory diagram briefly showing an algorithm related to a reactive power amount calculation process described later, which is related to the frequency measurement unit 21, the moving average value calculation unit 22, and the deviation amount calculation unit 24.

  C0 shown in FIG. 2 is a system cycle currently measured by the frequency measuring unit 21, C1 is a system cycle measured 5 ms before, and Cn is a measured value of the system cycle n * 5 ms before. Therefore, the moving average value calculation unit 22 calculates the latest moving average value sequentially in units of 5 milliseconds by moving average the system period for 40 milliseconds from C0 to C7. Since the moving average value is calculated in units of 5 milliseconds as shown in FIG. 3A, smooth moving average value fluctuation, that is, frequency fluctuation can be obtained as compared with FIG. 3B. It can be done. Also, as shown in FIGS. 4A and 5A, the predetermined moving average time is set to 40 milliseconds, so that the predetermined moving average time is shortened compared to FIG. 4B, and FIG. The moving average value reflecting the current operation state can be obtained by extending the predetermined moving average time as compared with (1).

  In addition, as shown in FIG. 2, when the past moving average value is the latest moving average value of C0 to C7, the moving period of 40 msec of C40 to C47 200 msec before C0 is moved and averaged. These are calculated sequentially in units of 5 milliseconds. The current deviation amount is calculated by the past moving average value (C40 to C47) −the latest moving average value (C7 to C0). The deviation amount is sequentially calculated based on the latest moving average value and the past moving average value 200 msec before the latest moving average value as shown in FIG. Even in comparison with b), it is possible to acquire a deviation amount that reflects the current operation status.

  The reactive power amount calculation unit 28 calculates the reactive power amount based on the deviation amount calculated by the deviation amount calculation unit 24 using the reactive power amount-deviation amount characteristic shown in FIG. The amount is notified to the output current control unit 29. Note that the reactive power amount-deviation amount characteristic shown in FIG. 6A has a dead zone range (first predetermined value X1 to second predetermined value X2) with a small deviation amount and a dead zone range other than the dead zone range with a large deviation amount. (Less than the first predetermined value X1 or more than the second predetermined value X2) is set. For example, when the current deviation amount becomes less than the first predetermined value X1, the reactive power amount is decreased, and the current deviation amount becomes the second predetermined value X2. If the current deviation amount is small and within the dead band range, the absolute value of the reactive power amount is corrected to be smaller than when the deviation amount is within the dead band range. is there. That is, even when the deviation amount (frequency fluctuation) is within a small dead band range, reactive power can be injected to detect the isolated operation of the distributed power source 2, and the absolute value of the reactive power amount can be sensed. By making it smaller than in the case of the band range, it is possible to reliably prevent erroneous detection of an isolated operation without being affected by the slow fluctuation of the system voltage.

  When the control circuit 18 of the isolated operation detection device 5 detects the isolated operation of the distributed power supply 2 through the isolated operation detection circuit 14, the connected connection between the distributed power supply 2 and the commercial system 3 is cut off through the connected relay circuit 16. At the same time, the connection between the distributed power source 2 and the commercial system 3 and the inverter circuit 11 is cut off through the relay circuit 17.

  The isolated operation detection device according to the claims is the isolated operation detection device 5, the distributed power supply is the distributed power supply 2, the commercial system is the commercial system 3, the reactive power injection circuit is the inverter circuit 11, and the frequency fluctuation detection circuit is the voltage detection circuit. 13 and the frequency measurement unit 21, the isolated operation detection circuit is the isolated operation detection circuit 14, the system cycle measurement means is the voltage detection circuit 13 and the frequency measurement unit 21, the moving average value calculation means is the moving average value calculation unit 22, and the moving average value storage The means corresponds to the moving average value storage unit 23, the deviation amount calculation means corresponds to the deviation amount calculation unit 24, and the reactive power amount calculation means corresponds to the reactive power amount calculation unit 28.

  Next, the operation of the distributed power supply system 1 showing this embodiment will be described. FIG. 3 is a flowchart showing the processing operation inside the inverter drive control circuit 15 related to the reactive power amount calculation processing of the isolated operation detection device 5 according to the present embodiment.

  The reactive power amount calculation process shown in FIG. 7 calculates the reactive power amount of reactive power to be injected between the distributed power source 2 and the commercial system 3 corresponding to the high speed detection of the isolated operation of the distributed power source 2. Process.

  In FIG. 7, when the frequency measuring unit 21 in the inverter drive control circuit 15 of the isolated operation detection device 5 detects the system voltage of the commercial system 3 through the voltage detection circuit 13, the system period of this system voltage is sequentially measured in units of 5 milliseconds. (Step S11), the system cycle in units of 5 milliseconds is sequentially stored in the moving average value calculation unit 22 (Step S12).

  The moving average value calculation unit 22 sequentially calculates the moving average value based on the system cycle for 40 milliseconds that is being stored (step S13), and sequentially stores these moving average values in the moving average value storage unit 23 (step S13). S14).

  The deviation amount calculation unit 24 reads the latest moving average value stored in the moving average value storage unit 23 and the past moving average value 200 msec before the latest moving average value, and these read latest moving average values. Deviation amounts are sequentially calculated based on the value and the past moving average value (step S15).

  The gain unit 25 performs gain adjustment on the deviation amount calculated by the deviation amount calculation unit 24 (step S16), and the limiter unit 26 ensures that the gain adjustment-adjusted deviation amount falls within the input range of the reactive power amount calculation unit 28. (Step S17).

  The reactive power amount calculating unit 28 calculates a reactive power amount corresponding to the deviation amount suppressed through the limiter unit 26 based on the reactive power amount-deviation amount characteristic shown in FIG. 6A (step S18).

  The reactive power amount calculating unit 28 adds the reactive power amount corresponding to the current deviation amount and the reactive power amount of the periodic variation unit 27 to calculate the injected reactive power amount that the inverter circuit 11 should inject ( In step S19), the calculated injection reactive power amount is notified to the output current control unit 29, thereby ending this processing operation.

  The output current control unit 29 generates an output current corresponding to the injected reactive energy, and supplies this output current to the inverter circuit 11, so that a line between the distributed power source 2 and the commercial system 3 is supplied from the inverter circuit 11. Reactive power corresponding to the injected reactive power amount is injected. As a result, high-speed injection of reactive power to the line between the distributed power source 2 and the commercial system 3 corresponding to the high-speed detection of the single operation of the distributed power source 2 can be realized.

  According to the present embodiment, the system period of the commercial system 3 is sequentially measured in units of 5 milliseconds corresponding to 1/3 or less of the system period of the commercial system 3, and based on the system period in units of 5 milliseconds measured sequentially, The moving average value of the system cycle for continuous 40 milliseconds is sequentially calculated, and the sequentially calculated moving average value is sequentially stored, and the latest moving average value stored in the memory and the latest moving average value 200 ms before The past moving average value is read out, the latest moving average value read out and the deviation amount of the past moving average value are calculated, and the reactive power amount of the reactive power injected by the inverter circuit 11 based on the calculated deviation amount By calculating the moving average value that is the basis of the deviation amount for calculating the reactive power amount in the system cycle of 5 milliseconds corresponding to 1/3 or less of the system cycle of the commercial system 3. Fine-grained movement Since the fluctuation of the average value, that is, the fluctuation of the deviation amount can be smoothed, even if the reactive power amount of the reactive power to be injected between the distributed power source 2 and the commercial system 3 is increased, it is supplied to the inverter circuit 11. A sudden change in the current waveform can be prevented, and as a result, high-speed injection of reactive power suitable for detecting single operation of the distributed power source 2 at high speed can be realized.

  Further, according to the present embodiment, a dead zone range in which the deviation amount calculated by the deviation amount calculation unit 24 is small is set in advance, and when the current deviation amount is within the dead zone range, Compared to the case, since the reactive power amount is calculated by correcting the absolute value of the reactive power amount of the reactive power injected by the inverter circuit 11 to be small, even if the deviation amount is within a small dead band range The reactive power can be injected to detect the isolated operation of the power source 2, and the absolute value of the reactive power amount, that is, the absolute value of the injected amount is compared with the sensitive range with a large deviation amount. By making it smaller, it is possible to reliably prevent erroneous detection of isolated operation due to frequency fluctuations of reactive power injection in the dead zone range where the deviation amount is small.

  Further, according to the present embodiment, since the system cycle of the commercial system 3 is sequentially measured in units of 5 milliseconds, the movement that is the basis of the deviation amount for calculating the reactive power amount in the system period in units of 5 milliseconds. By calculating the average value, it is possible to smooth the fluctuation of the fine moving average value, that is, the fluctuation of the deviation amount, so that the reactive power amount of the reactive power to be injected between the distributed power source 2 and the commercial system 3 is increased. Even so, it is possible to prevent a sudden change in the current waveform supplied to the inverter circuit 11, and as a result, for example, high-speed injection of reactive power suitable for detecting single operation of the distributed power source 2 at high speed in about 100 milliseconds. Can be realized.

  Further, according to the present embodiment, since the moving average value of the continuous system period for 40 milliseconds is sequentially calculated based on the system period sequentially measured in units of 5 milliseconds, the moving average value is calculated. In consideration of the time required for this processing, the predetermined moving average time is set to 40 milliseconds, so that the isolated operation of the distributed power source 2 can be detected at high speed in about 100 milliseconds, for example.

  Further, according to the present embodiment, the latest moving average value being stored and the past moving average value 200 msec before the latest moving average value are read, and the read latest moving average value and 200 msec are read out. Since the deviation amount of the previous past moving average value is calculated for each system cycle in units of 5 ms, by setting the past moving average value to the moving average value 200 ms before the latest moving average value, In addition to facilitating separation during single operation and normal operation, it is possible to reliably recognize frequency disturbance when a power failure occurs in the commercial system 3. Even if the reactive power amount of the reactive power to be injected is increased, a sudden change in the current waveform supplied to the inverter circuit 11 can be prevented. As a result, for example, the isolated operation of the distributed power source 2 can be performed at high speed in about 100 milliseconds. Inspection It is possible to realize a high-speed injection of the reactive power that is suitable for.

  In addition, in the said embodiment, although the independent operation detection apparatus 5 was separately arrange | positioned between the power conditioner apparatus 4 and the commercial system 3, of course, the independent operation detection apparatus in the power conditioner apparatus 4 inside. It goes without saying that the same effect can be obtained even if 5 is incorporated.

  In the above embodiment, the frequency measurement unit 21 sequentially measures the system cycle in units of 5 milliseconds. For example, the system period is sequentially measured in units of 20 milliseconds, which is the system period, and this measurement is sequentially performed. It is needless to say that the same effect can be obtained by applying a low-pass filter process with a period of, for example, 5 milliseconds to the system period, so that fine movement average value fluctuations, that is, deviation amount fluctuations can be smoothed. .

  According to the isolated operation detection device of the present invention, the system cycle of the commercial system is sequentially measured in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system, and the system of the measurement cycle unit that is sequentially measured Based on the cycle, the moving average value of the system cycle for the continuous predetermined moving average time is sequentially calculated, and the sequentially calculated moving average value is sequentially stored, the latest moving average value in the storage and the latest moving The past moving average value of a predetermined time before is read from the average value, the latest moving average value read out and the deviation amount of the past moving average value are calculated, and based on the calculated deviation amount, the reactive power injection circuit Since the reactive power amount of the reactive power to be injected is calculated, the basis of the deviation amount for calculating the reactive power amount in the system cycle of the measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system And By calculating the moving average value, it is possible to smooth the fluctuation of the fine moving average value, that is, the fluctuation of the deviation amount, so that the reactive power amount of the reactive power to be injected between the distributed power source and the commercial system is increased. Even in this case, it is possible to prevent a sudden change in the current waveform supplied to the reactive power injection device, and as a result, it is possible to realize high-speed injection of reactive power suitable for detecting single operation of the distributed power source at high speed. Therefore, it is useful for a distributed power supply system that interconnects a distributed power supply and a commercial system.

It is a block diagram which shows schematic structure inside the distributed power supply system which shows embodiment in connection with the isolated operation detection apparatus of this invention. It is operation | movement explanatory drawing which shows directly the algorithm regarding the reactive energy calculation process in connection with the frequency measurement part of the isolated operation detection apparatus in connection with this Embodiment, a moving average value calculation part, and a deviation amount calculation part. It is comparative explanatory drawing which shows the fluctuation | variation of the moving average value of the isolated operation detection apparatus in connection with this Embodiment. It is comparative explanatory drawing which shows the fluctuation | variation of the moving average value of the isolated operation detection apparatus in connection with this Embodiment from the standpoint of moving average time (long period). It is comparative explanatory drawing which shows directly the fluctuation | variation of the moving average value of the isolated operation detection apparatus in connection with this Embodiment from the viewpoint of moving average time (short cycle). It is comparison explanatory drawing which shows directly the reactive power amount-deviation amount characteristic of the isolated operation detection apparatus in connection with this Embodiment. It is a flowchart which shows the processing operation inside the inverter drive control circuit regarding the reactive energy calculation process of the isolated operation detection apparatus in connection with this Embodiment.

Explanation of symbols

2 Distributed power supply 3 Commercial system 5 Independent operation detector 11 Inverter circuit (reactive power injection circuit)
13 Voltage detection circuit (frequency fluctuation detection circuit and system cycle measurement means)
14 Isolated operation detection circuit 21 Frequency measurement unit (frequency fluctuation detection circuit and system cycle measurement means)
22 Moving average value calculation unit (moving average value calculation means)
23 Moving average value storage unit (moving average value storage means)
24 Deviation amount calculation unit (deviation amount calculation means)
28 Reactive energy calculation unit (Reactive energy calculation means)

Claims (5)

A reactive power injection circuit that injects reactive power between a distributed power source and a commercial system, a frequency fluctuation detection circuit that detects a frequency fluctuation of the reactive power injected by the reactive power injection circuit, and a frequency fluctuation detection circuit An isolated operation detection device having an isolated operation detection circuit for detecting isolated operation of the distributed power source based on the detected frequency fluctuation,
System cycle measuring means for measuring the system cycle of the commercial system in a measurement cycle unit corresponding to 1/3 or less of the system cycle of the commercial system;
Based on the system cycle of the measurement cycle unit sequentially measured by this system cycle measuring means, moving average value calculating means for sequentially calculating the moving average value of the system cycle for a continuous predetermined moving average time;
Moving average value storage means for sequentially storing the moving average values sequentially calculated by the moving average value calculation means;
The latest moving average value stored in the moving average value storage means and the past moving average value of a predetermined time before are read from the latest moving average value, and these read latest moving average value and past moving average value are read out. Deviation amount calculating means for calculating the deviation amount of each system cycle of the measurement cycle unit,
An isolated operation detecting device comprising: a reactive power amount calculating means for calculating a reactive power amount of the reactive power injected by the reactive power injection circuit based on the deviation amount calculated by the deviation amount calculating means. . The reactive energy calculation means includes
A dead zone range in which the deviation amount is small is set in advance,
When the deviation amount calculated by the deviation amount calculation means is within the dead band range, the reactive power of the reactive power injected by the reactive power injection circuit is larger than when the deviation amount is outside the dead band range. The isolated operation detection device according to claim 1, wherein the reactive power amount is calculated by correcting an absolute value of the amount to be small. The measurement cycle unit is
The islanding operation detection device according to claim 1 or 2, which corresponds to a unit of 5 milliseconds which is 1/3 or less of a system cycle of the commercial system. The predetermined moving average time is
4. The system according to claim 1, 2, or 3, characterized in that it is longer than a system cycle of the commercial system and corresponds to 40 milliseconds which is a time during which the single operation detection circuit can detect the single operation at high speed. Single operation detection device. The past moving average before the predetermined time is:
It corresponds to a past moving average value 200 msec before the latest moving average value, which is a time during which the isolated operation detecting circuit can detect the isolated operation at high speed. The isolated operation detection device according to 3 or 4.

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