JP5389065B2 - Isolated operation detection system and isolated operation detection method for distributed power supply - Google Patents

Description

The present invention relates to isolated operation detecting system Contact and isolated operation detecting method of distributed power.

In recent years, distributed power sources such as small-scale power generation facilities using natural energy and cogeneration facilities are linked to the distribution lines. In such a distribution system, when the supply of power from the power company's substation to the distribution line stops, in order to prevent electric shock, etc., the distributed power supply is disconnected from the distribution line to prevent isolated operation. There is a need to.
For example, in Patent Document 1, by injecting a harmonic current of an intermediate order that is a non-integer multiple of the fundamental wave of a distribution system into a lead-in line to a customer facility, and measuring the harmonic voltage of the intermediate order at a power receiving point, An isolated operation detection device that detects an isolated operation of a distributed power source is disclosed. And when isolated operation is detected, the circuit breaker of a consumer facility can be opened and a distributed power supply can be disconnected from a distribution line.
In this way, in a customer facility having a distributed power supply, by injecting and measuring harmonics, it is possible to detect an isolated operation of the distributed power supply and prevent an electric shock accident or the like due to the isolated operation.

JP 2000-287362 A

However, the provision of such an isolated operation detection device in all customer facilities increases the installation cost. Further, in the customer facility, when harmonics are injected, not only the isolated operation cannot be detected due to interference between harmonics, but also the possibility of affecting the fundamental wave of the distribution system.
Therefore, as the distributed power source becomes more widespread and the distributed power source connected to the distribution line increases, it becomes more difficult to introduce the independent operation detection device to each customer facility.

Primary aspect of the present invention to solve the problems described above, the distribution substation for supplying power to the distribution line via a respective from the secondary side of the plurality of power transformers first circuit breaker, a transformer for the plurality of power a plurality of signal injection device for injecting an AC signal of a predetermined frequency, respectively to zero-phase circuit of the secondary side of the vessel is an integral multiple of a commercial power frequency is interconnection to the distribution line through a second circuit breaker that the customer facility with distributed power, and a signal detector for detecting the component of the predetermined frequency included in the zero-phase voltage of the distribution line, each of said plurality of signal injection device, the plurality of An AC signal generation circuit that generates the AC signal synchronized with any one phase of the secondary side of the power transformer, and the AC signal input to the primary side is transformed and injected into the zero-phase circuit. A first instrument transformer, The signal detection device includes: a second instrument transformer that detects the zero-phase voltage; and a filter circuit that passes a frequency band including the predetermined frequency of the zero-phase voltage. This is an isolated operation detection system for distributed power sources.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  According to the present invention, it is possible to detect a single operation of a distributed power source at low cost without affecting the power distribution system.

It is a circuit block diagram which shows the structure of the independent operation | movement detection system of the distributed power supply in 1st Embodiment of this invention. It is a schematic diagram which shows each phase of a three-phase alternating current when the injection signal v1 is not injected. It is a schematic diagram which shows an example of the injection signal v1 inject | poured into the zero phase circuit of the secondary side of the power transformer 2. FIG. In 1st Embodiment of this invention, it is a schematic diagram which shows an example of the three-phase alternating current in which the injection signal v1 was inject | poured. FIG. 6 is a schematic diagram illustrating an example of a detection signal Vdt detected in the first embodiment of the present invention. It is a circuit block diagram which shows the other structural example of the signal injection apparatus in a non-grounding system. It is a circuit block diagram which shows the structural example of the signal injection apparatus in a resistance grounding system. It is a circuit block diagram which shows the structural example of the signal injection apparatus in an arc-extinguishing reactor grounding system. It is a circuit block diagram which shows the structural example of the signal injection apparatus in a compensation reactor grounding system. It is a circuit block diagram which shows the other structural example of a signal detection apparatus. It is a circuit block diagram which shows the other structural example of a signal detection apparatus. It is a block diagram which shows the structure of the isolated operation detection system of the distributed power supply in 2nd Embodiment of this invention. In 2nd Embodiment of this invention, it is a schematic diagram which shows an example of the relationship between 3 phase alternating current and injection signal v1 and v4. In 2nd Embodiment of this invention, it is a schematic diagram which shows an example of the three-phase alternating current in which the injection signals v1 and v4 were inject | poured. In 2nd Embodiment of this invention, it is a schematic diagram which shows an example of the detection signal Vdt detected.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

<First Embodiment>
=== Configuration of islanding detection system ===
Hereinafter, with reference to FIG. 1, the structure of the isolated operation detection system of the distributed power supply in the 1st Embodiment of this invention is demonstrated. Here, the case where the power is supplied to the distribution line 5 from one power transformer 2 of the distribution substation and one distributed power source 8 is connected to the distribution line 5 will be described.

  The isolated operation detection system shown in FIG. 1 includes a signal injection device 1a, a power transformer 2, and a circuit breaker 3 installed in a distribution substation, a relay 6 installed in a customer facility, and a circuit breaker. 7, a distributed power supply 8, and a signal detection device 9 a.

  The signal injection device 1a includes an AC signal generation circuit 11 and an instrument transformer 12 (first instrument transformer). An AC signal generation circuit 11 is connected to the primary winding of the instrument transformer 12. Furthermore, one end of the secondary winding of the instrument transformer 12 is connected to the secondary neutral point of the power transformer 2 and the other end is grounded.

  The power transformer 2 is assumed to be a YY-Δ connection transformer, for example. Further, the primary Y winding and the secondary Y winding of the power transformer 2 are connected to the primary bus 21 and the secondary bus 22, respectively. The distribution line 5 is connected to the secondary bus 22 via the circuit breaker 3 (first circuit breaker).

  The distributed power supply 8 includes a generator 81 and a power transformer 82. Moreover, the power transformer 82 is assumed to be a Δ-Y connection transformer, for example. Furthermore, the generator 81 is connected to the Δ winding of the power transformer 82, and the Y winding is connected to the distribution line 5 via the circuit breaker 7 (second circuit breaker).

  The signal detection device 9a includes an instrument transformer 91 (second instrument transformer), a filter circuit 92, and a resistor 93. One end of the primary winding of the instrument transformer 91 is connected to the secondary neutral point of the power transformer 82 and the other end is grounded. Further, the zero-phase voltage V0 output from the secondary winding of the instrument transformer 91 is input to the filter circuit 92, and the voltage across the resistor 93 is output from the filter circuit 92 as the detection signal Vdt. The detection signal Vdt is input to the relay 6, and the cutoff command signal Sop output from the relay 6 is input to the breaker 7.

=== Operation of islanding detection system ===
Next, with reference to FIGS. 2 to 5 as appropriate, the operation of the isolated operation detection system for a distributed power source according to this embodiment will be described.

  The power transformer 2 of the distribution substation, for example, receives a voltage of about several tens to hundreds of kV from the primary side bus 21, converts it to a voltage of about several kV, and sends it to the secondary side bus 22. . The AC signal generation circuit 11 of the signal injection device 1a generates an AC signal having a predetermined frequency f1 higher than the commercial power supply frequency f0. Further, the instrument transformer 12 transforms the AC signal input to the primary side and inputs it as an injection signal v1 to the secondary side neutral point of the power transformer 2. The injection signal v1 is injected into the secondary phase zero-phase circuit of the power transformer 2 and superimposed on each phase of the three-phase AC.

  Here, as an example, when the injection signal v1 is not injected, the three-phase alternating current sent to the secondary bus 22 and the injection signal v1 injected into the secondary-side zero-phase circuit of the power transformer 2 Are shown in FIGS. 2 and 3, respectively. In FIG. 2, the solid line, the alternate long and short dash line, and the broken line indicate each phase of three-phase alternating current. Further, A in FIG. 2 indicates the amplitude (sending voltage) of the three-phase alternating current, and a in FIG. 3 indicates the amplitude of the injection signal v1.

  The three-phase alternating current into which the injection signal v <b> 1 is injected is supplied to the distribution line 5 through the circuit breaker 3. FIG. 4 shows an example of a three-phase alternating current in which the injection signal v1 shown in FIG. 3 is injected, and an injection signal v1 having a frequency f1 is superimposed on each phase. In FIG. 4, f1 = 6 × f0. Further, a = A / 100, and the distortion of the three-phase alternating current due to the injection signal v1 is sufficiently small.

  As described above, in the distributed power supply 8 of the customer facility, the Y winding of the power transformer 82 is connected to the distribution line 5 via the circuit breaker 7. Therefore, the power transformer 82 transforms the generated voltage of the generator 81 so as to match the received voltage from the distribution line 5. In addition, the lead-in line from the distribution line 5 to the customer facility is connected to a load (not shown) via another power transformer (not shown), and the distribution line 5 and / or distributed to the load. Power is supplied from the power source 8.

  The instrument transformer 91 of the signal detector 9a has one end of the primary winding connected to the secondary neutral point of the power transformer 82, and detects and outputs the zero-phase voltage V0 of the distribution line 5. . Further, the filter circuit 92 detects a component of the frequency f1 through the frequency band including the frequency f1 of the injection signal v1 in the zero-phase voltage V0. Here, the component of the frequency f1 included in the zero-phase voltage V0 is detected as the detection signal Vdt (the voltage across the resistor 93). As an example, assuming that the transformer ratio of the instrument transformer 91 is 1, FIG. Thus, the detection signal Vdt having the amplitude 3a is detected.

  However, when the circuit breaker 3 is opened and the supply of power from the distribution substation to the distribution line 5 is stopped, the customer facility does not receive the three-phase alternating current on which the injection signal v1 is superimposed. The signal Vdt is not detected. Therefore, when the signal detection device 9a does not detect the detection signal Vdt, the single operation of the distributed power supply 8 can be detected. And when the detection signal Vdt is not input, the relay 6 outputs the interruption command signal Sop, opens the circuit breaker 7, and disconnects the distributed power supply 8 from the distribution line 5.

  In this way, in the distribution substation, the injection signal v1 of the frequency f1 (> f0) is injected into the secondary zero-phase circuit of the power transformer 2, and is included in the zero-phase voltage V0 in the customer facility. By detecting the component of the frequency f1 to be detected, the isolated operation of the distributed power supply 8 can be detected. Moreover, when the component of the frequency f1 is not detected, an isolated operation of the distributed power source 8 is detected, and the distributed power source 8 is disconnected from the distribution line 5, thereby preventing an electric shock accident due to the isolated operation.

=== Other Configuration Examples of Signal Injection Device and Signal Detection Device ===
In the isolated operation detection system of the distributed power source shown in FIG. 1, the signal injection device 1 a is connected to the secondary side neutral point of the non-grounded power transformer 2 through the instrument transformer 12. Although the signal v1) is input, the present invention is not limited to this.
For example, like the signal injection device 1b shown in FIG. 6, the AC signal generation circuit 11 is connected to the open delta using the grounded-type instrument transformer 13 (first instrument transformer), and two Y windings are connected. It may be connected to the secondary bus 22. In FIG. 6, as in FIG. 1, the power transformer 2 is not grounded, but the injection signal v1 can be injected into the zero-phase circuit even when the secondary side is Δ-connected. This is a highly versatile configuration.

  Further, when the power transformer 2 is of the resistance grounding type, both ends of the secondary winding of the instrument transformer 12 are connected to both ends of the resistor 14 as in the signal injection device 1c shown in FIG. Thus, the injection signal v1 can be injected into the secondary phase zero-phase circuit of the power transformer 2. Similarly, when the power transformer 2 is an arc extinguishing reactor grounding system, both ends of the secondary winding of the instrument transformer 12 are connected to both ends of the reactor 15 as in the signal injection device 1d shown in FIG. Connecting. Further, when the power transformer 2 is a compensated reactor grounding system, the AC signal generation circuit 11 is connected in parallel with the resistor 14 and the reactor 15 as in the signal injection device 1e shown in FIG.

In addition, it can also be set as the structure which uses the earthing | grounding type instrument transformer 13 in the case of a resistance grounding system and an arc-extinguishing reactor grounding system, and can be set as the structure which uses the instrument transformer 12 in the case of a compensation reactor grounding system.
On the other hand, the signal detection device 9a detects the zero-phase voltage V0 from the secondary side neutral point of the power transformer 82 via the instrument transformer 91, but is not limited thereto. In particular, in a customer facility equipped with a ground fault overvoltage relay or a ground fault direction relay that detects a ground fault, existing zero-phase voltage detection means can be used.
For example, a zero-phase voltage V0 can be detected by using a capacitor-type zero-phase voltage detection device including capacitors 94 to 97 and an instrument transformer 91 as in a signal detection device 9b shown in FIG. Further, for example, a zero-phase voltage V0 can be detected by using a grounded instrument transformer 98 having a limiting resistor connected to an open delta, as in a signal detection device 9c shown in FIG.

Second Embodiment
=== Configuration of islanding detection system ===
Hereinafter, the configuration of the isolated operation detection system for a distributed power supply according to the second embodiment of the present invention will be described with reference to FIG. Here, power is supplied to a distribution line from a plurality (two) of power transformers 102 and 402, and a plurality (three) of distributed power sources 108, 208, and 308 are connected to the distribution line. The case of the system will be described. Note that a plurality of power transformers may be installed in the same substation, and there may be substations that do not include a power transformer, such as substations 2 and 3.

In FIG. 12, a signal injection device 101, a power transformer 102, and a circuit breaker 103 are installed in the (distribution) substation 1 and have the same configuration as the distribution substation in FIG. Similarly, the substation 4 is provided with a signal injection device 401, a power transformer 402, and a circuit breaker 403, and has the same configuration as the distribution substation of FIG.
On the other hand, the substation 2 is provided with circuit breakers 203 and 204, and the substation 3 is provided with circuit breakers 303 and 304. Further, the distribution line drawn from the substation 1 through the circuit breaker 103 and the distribution line drawn from the substation 4 through the circuit breaker 403 are connected via the circuit breakers 203, 204, 303, and 304. Are connected to each other.

  The customer (facility) 1 is provided with a circuit breaker 107, a distributed power source 108, and a signal detection device 109, and has the same configuration as the customer facility of FIG. Similarly, the customer 2 is provided with a circuit breaker 207, a distributed power source 208, and a signal detection device 209, and has the same configuration as the customer facility of FIG. Further, similarly, the customer 3 is provided with a circuit breaker 307, a distributed power source 308, and a signal detection device 309, and has the same configuration as the customer facility of FIG. In addition, in FIG. 12, the relay which inputs the interruption command signal Sop to each circuit breaker is not illustrated.

  A distributed power source 108 is connected to the distribution line drawn from the substation 1 via the circuit breaker 103 via the circuit breaker 107. Further, a distributed power source 208 is connected to the distribution line drawn from the substation 2 via the circuit breaker 204 via the circuit breaker 207. Further, a distributed power source 308 is connected to the distribution line drawn from the substation 4 via the circuit breaker 403 via the circuit breaker 307.

=== Operation of islanding detection system ===
Next, with reference to FIGS. 13 to 15 as appropriate, the operation of the isolated operation detection system of the distributed power source in the present embodiment will be described.

  Similarly to the power transformer 2, the power transformer 102 of the substation 1 and the power transformer 402 of the substation 4 receive, for example, a voltage of about tens to hundreds of kV from the primary bus, The voltage is converted to a voltage of about several kV and sent to the secondary bus. The signal injection device 101 injects an injection signal v1 into the secondary-side zero-phase circuit of the power transformer 102, and the signal injection device 401 injects into the secondary-side zero-phase circuit of the power transformer 402. Inject signal v4.

  Here, the injection signals v1 and v4 are AC signals having a frequency f1 (> f0) synchronized with each other. For example, as shown in FIG. 13, the injection signals v1 and v4 can be synchronized with each other by setting the frequency f1 to an integral multiple of the commercial power supply frequency f0 and synchronizing it with one of the three-phase alternating currents. Further, for example, each signal injection device has a GPS (Global Positioning System) receiver, and based on the accurate current time received and calibrated by receiving GPS signals transmitted from four GPS satellites. The injection signals v1 and v4 can also be synchronized with each other. Further, for example, the injection signal v1 may be separately transmitted to the substation 4 and the injection signal v4 may be synchronized with the injection signal v1.

  The three-phase alternating current into which the injection signals v1 and v4 are injected is supplied to the distribution line (network) via the circuit breakers 103 and 403. FIG. 14 shows an example of a three-phase alternating current in which the injection signals v1 and v4 shown in FIG. 13 are injected. An alternating current signal having a frequency f1 synchronized with each other is superimposed on each phase. In FIG. 14, f1 = 6 × f0. Further, a = A / 50, and the distortion of the three-phase alternating current due to the injection signals v1 and v4 is sufficiently small. And the signal detection apparatuses 109, 209, and 309 detect the component of the frequency f1 included in the zero-phase voltage V0 of the distribution line as the detection signal Vdt, for example, as shown in FIG.

In this embodiment, the conditions for detecting the isolated operation of the distributed power supply are different for each consumer.
For example, the distributed power source 108 of the customer 1 does not operate independently while electric power is supplied from the substation 4 via the substations 3 and 2 even if the circuit breaker 103 of the substation 1 is opened. Therefore, when at least one of the circuit breakers 203, 204, 303, 304, and 403 is opened in addition to the circuit breaker 103, the signal detection device 109 does not detect the detection signal Vdt, and the distributed power supply 108 is operated independently. Can be detected. And the interruption | blocking command signal Sop is input into the circuit breaker 107 from a relay (not shown), and the distributed power supply 108 is disconnected from a distribution line.

  Further, in the customer 2, when the at least one of the circuit breakers 103, 203, and 204 and at least one of the circuit breakers 303, 304, and 403 are opened, the isolated operation of the distributed power source 208 is detected. Can do. Further, in the customer 3, in addition to the circuit breaker 403, when at least one of the circuit breakers 103, 203, 303, and 304 is opened, it is possible to detect the isolated operation of the distributed power source 308.

  In this way, AC signals of frequencies f1 (> f0) synchronized with each other are injected into the secondary-side zero-phase circuit of each power transformer, and each signal detection device has the frequency f1 included in the zero-phase voltage V0. By detecting the components, the single operation of each distributed power source can be detected. Moreover, when the component of the frequency f1 is not detected, it is possible to prevent an electric shock accident due to the single operation by detecting the single operation of each distributed power source and disconnecting from the distribution line.

  As is clear from the above, in the isolated operation detection system of the distributed power supply of this embodiment, a signal injection device is provided for each power transformer that supplies power to the distribution line, and only the signal detection device is provided for each distributed power supply. What is necessary is just to provide. Therefore, the installation cost of the isolated operation detection device can be reduced.

  As described above, in the distributed power supply isolated operation detection system shown in FIG. 1, the predetermined frequency f1 higher than the commercial power supply frequency f0 is injected into the secondary phase circuit of the power transformer 2 in the distribution substation. By injecting signal v1 and detecting the component of frequency f1 included in the zero-phase voltage V0 of distribution line 5 at the customer's facility, the isolated operation of distributed power supply 8 is detected at low cost without affecting the distribution system. can do.

  In addition, in the isolated operation detection system of the distributed power source shown in FIG. 12, AC signals of frequencies f1 synchronized with each other are injected into the secondary-side zero-phase circuit of each power transformer, and each signal detection device By detecting the component of frequency f1 included in V0, even when power is supplied to the distribution line from a plurality of power transformers, the distribution system is not affected, and each distributed power source is operated at low cost. Can be detected.

  In addition, each AC signal can be synchronized with each other by setting the frequency f1 to be an integral multiple of the commercial power supply frequency f0 and synchronizing the injected AC signal with any one of the three-phase ACs.

  Further, when the signal detection device does not detect the component of the frequency f1, it is possible to prevent an electric shock accident due to an isolated operation by disconnecting the distributed power source from the distribution line.

  Further, in the signal detection devices 9a to 9c, by detecting the component of the frequency f1 included in the zero-phase voltage V0 of the distribution line 5 in the customer facility, the secondary side of the power transformer 2 of the distribution substation is detected. By using an injection signal v1 having a predetermined frequency f1 higher than the commercial power supply frequency f0 injected into the zero-phase circuit, it is possible to detect the isolated operation of the distributed power supply 8 at a low cost without affecting the distribution system.

  Moreover, when the component of the frequency f1 is not detected, an electric shock accident or the like due to an isolated operation can be prevented by disconnecting the distributed power source from the distribution line.

  Moreover, the commercial power supply frequency injected into the secondary phase zero-phase circuit of the power transformer of the distribution substation by detecting the component of the frequency f1 included in the zero-phase voltage V0 of the distribution line in the customer facility When an AC signal having a predetermined frequency f1 higher than f0 is used and no component of the frequency f1 is detected, it is possible to detect the isolated operation of the distributed power source.

  In addition, the said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 1a-1e Signal injection apparatus 2 Electric power transformer 3, 7 Circuit breaker 5 Distribution line 6 Relay 8 Distributed power supply 9a-9c Signal detection apparatus 11 AC signal generation circuit 12 Instrument transformer 13 Grounding type instrument transformer 14 Resistance 15 Reactor 21 Primary side bus 22 Secondary side bus 81 Generator 82 Power transformer 91 Instrument transformer 92 Filter circuit 93 Resistor 94 to 97 Capacitor 98 Grounded instrument transformer 101, 401 Signal injection device 102, 402 For power Transformer 103, 203, 204, 303, 304, 403 Breaker 107, 207, 307 Breaker 108, 208, 308 Distributed power supply 109, 209, 309 Signal detection device

Claims (3)

In a distribution substation that supplies power to the distribution line from the secondary side of each of the plurality of power transformers via the first circuit breaker, each of the zero-phase circuits on the secondary side of the plurality of power transformers A plurality of signal injection devices for injecting an alternating current signal having a predetermined frequency that is an integer multiple of the commercial power supply frequency;
In a customer facility having a distributed power source that is linked to the distribution line via a second circuit breaker, a signal detection device that detects a component of the predetermined frequency included in a zero-phase voltage of the distribution line;
With
Each of the plurality of signal injection devices includes:
An AC signal generation circuit for generating the AC signal that is synchronized with any one phase of the secondary side of the plurality of power transformers ;
A first instrument transformer that transforms the AC signal input to the primary side and injects it into the zero-phase circuit;
Have
The signal detection device includes:
A second instrument transformer for detecting the zero-phase voltage;
A filter circuit that passes a frequency band including the predetermined frequency of the zero-phase voltage;
An isolated operation detection system for a distributed power source, comprising: The relay device further comprises a relay that opens the second circuit breaker and disconnects the distributed power source from the distribution line when the signal detection device does not detect the component of the predetermined frequency. The isolated operation detection system of the distributed power source according to 1 . In distribution substations that supply power to the distribution lines from the secondary side of multiple power transformers,
Each of the plurality of power transformers is synchronized with any one phase of the secondary side, and generates an AC signal having a predetermined frequency that is an integer multiple of the commercial power supply frequency.
Injecting the AC signal to the secondary phase zero-phase circuit of the plurality of power transformers,
In customer equipment having a distributed power source linked to the distribution line ,
Detecting the zero-phase voltage of the distribution line,
Of the zero-phase voltage, a frequency band including the predetermined frequency is passed by a filter circuit,
An isolated operation detection method for a distributed power source, wherein the isolated operation of the distributed power source is detected when a component of the predetermined frequency included in the zero-phase voltage is not detected.

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