JP5389066B2 - Isolated operation detection system and isolated operation detection method for distributed power supply - Google Patents

Description

  The present invention relates to an isolated operation detection system and an isolated operation detection method for a distributed power source.

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.

The main present invention that solves the above-described problems is a distribution substation that supplies power to the distribution line from the secondary side of the power transformer via the first circuit breaker, and has a rising edge at a predetermined phase of the commercial power source. or a falling signal source for supplying an injection signal having an edge, the signal having a first voltage transformer for injecting the zero-phase circuit of the secondary side of the injection signal and transforms the power transformer In a customer facility having a distributed power source linked to the distribution line via an injection device and a second circuit breaker, a second instrument transformer for detecting a zero-phase voltage of the distribution line, And a signal detection device that detects a component of the injection signal included in the zero-phase voltage.

  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 circuit block diagram which shows an example of a specific structure of the signal source 11a. The schematic diagram which shows an example of the relationship between 1 phase of three-phase alternating current in the distribution substation, and the injection signal v1 inject | poured into the secondary-side zero phase circuit of the power transformer 2 in 1st Embodiment of this invention. It is. In 1st Embodiment of this invention, it is a schematic diagram which shows an example of the relationship between the detection signal Vdt and one phase of three-phase alternating current in a consumer facility. In 1st Embodiment of this invention, it is a schematic diagram which shows an example of the relationship between the detection signal Vdt and one phase of the three-phase alternating current in other customer facilities. 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 circuit block diagram which shows the other structural example of the signal source using a thyristor. It is a schematic diagram which shows an example of the relationship between 3 phase alternating current at the time of using the signal source shown in FIG. 12, and the injection signal v1. FIG. 10 is a circuit block diagram showing still another configuration example of a signal source using a thyristor. It is a schematic diagram which shows an example of the relationship between 3 phase alternating current at the time of using the signal source shown in FIG. 14, and the injection signal v1. It is a circuit block diagram which shows the structural example of the signal source which outputs a rectangular wave (square wave). FIG. 17 is a schematic diagram illustrating an example of a relationship between one phase of three-phase alternating current and an injection signal v1 when the signal source illustrated in FIG. 16 is used. It is a circuit block diagram which shows the structural example of the signal source which outputs a sawtooth wave (sawtooth wave). It is a schematic diagram which shows an example of the relationship between one phase of three-phase alternating current at the time of using the signal source shown in FIG. 18, and injection signal v1. 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.

  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 and FIG. 2, 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 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 signal injection device 1a includes a signal source 11a and an instrument transformer 12 (first instrument transformer). A signal source 11 a 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.

  As shown in FIG. 2, the signal source 11 a includes a thyristor 111 and a phase control circuit 112. Thyristor 111 is connected to one phase of secondary bus 22. Further, the one-phase voltage signal (or current signal) is input to the phase control circuit 112, and the output of the phase control circuit 112 is connected to the gate of the thyristor 111.

  In FIG. 2, the cathode of the thyristor 111 is connected to the R phase, and the R phase voltage R0 is input to the phase control circuit 112, but the present invention is not limited to this. The thyristor 111 may be connected to the S phase or the T phase. When the anode is appropriately connected to the secondary bus 22 according to the signal to be output from the signal source 11a, or when a bidirectional thyristor is used. There is also.

  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 9 a includes an instrument transformer 91 (second instrument transformer) 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 output from the secondary winding of the instrument transformer 91 is detected as a voltage across the resistor 93 and output as a 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. 3 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 signal source 11a of the signal injection device 1a generates an injection signal having a rising edge or a falling edge at a predetermined phase of the commercial power source. Further, the instrument transformer 12 transforms the injection 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 alternating current, and the three-phase alternating current injected with the injection signal v1 is the circuit breaker 3 To the distribution line 5.

  Here, as an example, the R-phase voltage R0 (solid line) of the secondary bus 22 and the injection signal v1 (short broken line) when the thyristor 111 whose cathode is connected to the R-phase is ignited at a phase angle of 270 °. FIG. 3 shows the relationship. As shown in FIG. 3, the injection signal v1 in this case has a negative half-wave rectified waveform with an ignition angle α = 90 °. 3, 13, 15, 17, and 19, the three-phase alternating current and the injection signal v <b> 1 are different in the scale of the vertical axis (amplitude), and the actual injection signal v <b> 1 is three-phase. The distortion of the three-phase alternating current due to the injection signal v1 is sufficiently small with respect to the alternating current. In FIG. 3, θ0 indicates the phase angle from the falling edge of the injection signal v1 to the zero point, and θ0 = 180 ° −α.

  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 of the distribution line 5. The zero-phase voltage is detected as a detection signal Vdt (short broken line) having an amplitude corresponding to the transformation ratio of the instrument transformer 91, as shown in FIGS.

  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, at the distribution substation, the injection signal v1 synchronized with the predetermined phase of the commercial power supply is injected into the secondary phase circuit on the secondary side of the power transformer 2, and the zero level voltage is obtained at the customer facility. By detecting the component of the injection signal v1 included as the detection signal Vdt, the single operation of the distributed power supply 8 can be detected. Moreover, when the detection signal Vdt is not detected, the isolated operation of the distributed power supply 8 is detected, and the distributed power supply 8 is disconnected from the distribution line 5 to prevent an electric shock accident due to the isolated operation.

  In the present embodiment, the injection signal v1 has a falling edge at a predetermined phase, and the phase angle from the falling edge of the detection signal Vdt to the zero point can be obtained. Further, from the phase angle, the phase difference angle between the R-phase voltage R0 '(solid line in FIGS. 4 and 5) in the customer facility and the R-phase voltage R0 in the distribution substation can be obtained. For example, if the phase angles from the falling edge to the zero point of the detection signal Vdt in the customer facility shown in FIGS. 4 and 5 are θ1 and θ2, respectively, the phase difference angles for the distribution substation are θ1−θ0 and θ2−θ0.

  These phase difference angles indicate the phase lag or phase advance for the three-phase AC distribution substation in each customer facility, and can therefore be used to detect reverse power flow from the distributed power supply 8 to the distribution system. . In addition, when the distributed power source 8 is a DC power source such as solar power generation or when the distributed power source 8 includes a storage battery, when the DC power needs to be converted into AC power, the phase difference angle is set to the power. It can also be used to control active power and reactive power in the conditioner.

=== 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 sends the injection signal v <b> 1 to the secondary neutral point of the non-grounded power transformer 2 via the instrument transformer 12. Although it has entered, it is not limited to this.
For example, like the signal injection device 1b shown in FIG. 6, the signal source 11a is connected to the open delta using the grounded-type instrument transformer 13 (first instrument transformer), and the Y winding is connected to the secondary side. It may be connected to the 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 of a compensated reactor grounding system, the signal source 11a 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 from the secondary neutral point of the power transformer 82 via the instrument transformer 91, but is not limited to this. 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 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 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.

=== Other Configuration Examples of Signal Sources ===
The signal source 11a shown in FIG. 2 generates a negative half-wave rectified waveform having a firing angle α = 90 ° by thyristor phase control, and generates an injection signal having a falling edge at a phase angle 270 ° of the R phase. However, it is not limited to this.
For example, like the signal sources 11b to 11d shown in FIG. 12, a rectified waveform having a firing angle α = 60 ° or 120 ° is generated by using a voltage signal (or current signal) of a phase not connected to a thyristor. be able to. Since the signal sources 11b to 11d can be composed of a small number of power electronic components, the reliability of the isolated operation detection system of the distributed power source can be improved.

  In each of the signal sources 11b to 11d, each phase control circuit 113 includes a diode 1132 and resistors 1133 and 1134 connected in a loop on the secondary side of the instrument transformer 1131 and gates of the thyristor 111 at both ends of the resistor 1134. And the cathode are connected. In the signal source 11b, the anode of the thyristor 111 is connected to the R-phase, and the S-phase voltage S0 is input to the primary side of the instrument transformer 1131 so that the positive half-wave with the firing angle α = 120 °. A rectified waveform is generated, and an injection signal having a rising edge at a phase angle of R phase of 120 ° is generated. Similarly, the signal sources 11c and 11d generate injection signals having rising edges at S and T phase angles of 120 °, respectively.

  FIG. 13 shows the relationship between each phase of the three-phase alternating current and the injection signal v1 generated by synthesizing the outputs of the signal sources 11b to 11d. Since the injection signal v1 has rising edges for three phases whose phases are shifted by 120 ° in one cycle of the commercial power supply, in addition to detecting the independent operation of the distributed power supply 8, the injection signal v1 is used for power distribution. Information can also be transmitted from substations to customer equipment. Similarly to the case of the signal source 11a, the phase difference angle with respect to the distribution substation is obtained and used for detection of reverse power flow from the distributed power source 8 to the distribution system, control of active power and reactive power in the power conditioner, and the like. Can do.

Further, for example, as in the signal sources 11e to 11f shown in FIG. 14, by making the resistor 1133 or 1134 variable, the two-phase ignition can be made variable, and the time difference from the fixed one-phase ignition can be distributed. It can also be transmitted as information from an industrial substation. As an example, the firing angle of the R phase is fixed to α _R = 120 °, the firing angle of the S phase is variable within a range of α _S = 120 ° ± 30 ° by the variable resistor VR1, and the firing angle of the T phase Can be varied in the range of α _T = 120 ° ± 30 ° by the variable resistor VR2.
In this case, as shown in FIG. 15, the time difference T _RS of the rising edge between the R phase and the S phase and the time difference T _RT of the rising edge between the R phase and the T phase are obtained, and T _RS = (1 / f), respectively.・ (120 ° / 360 °) + β,
T _RT = (1 / f) · (240 ° / 360 °) + γ
The variable information β and γ can be calculated as follows. Note that f is a commercial power supply frequency, and β and γ are
− (1 / f) · (30 ° / 360 °) ≦ β, γ ≦ (1 / f) · (30 ° / 360 °)
It becomes the range.

  Thus, by making the two-phase firing variable, two variable information (analog information) due to the time difference from the fixed one-phase firing and one depending on the presence or absence of the fixed one-phase rising edge Fixed information (binary information) can be transmitted. In particular, by using two variable information, the active power and reactive power can be controlled in more detail. Furthermore, by generating a full-wave rectified waveform, five variable information and one fixed information can be transmitted.

  In the thyristor phase control, an injection signal having a rising edge or a falling edge at a phase angle of 0 ° or 180 ° cannot be generated. On the other hand, by generating a rectangular wave (square wave) or a sawtooth wave (sawtooth wave) like the signal sources 11g and 11h shown in FIGS. 16 and 18, respectively, a rising edge or falling edge at a phase angle of 0 ° is generated. An injection signal having edges can be generated.

  In the signal source 11g, the control circuit 114 performs ON / OFF control of the NPN transistors T1 to T4, each of which has a diode connected in antiparallel, thereby causing a falling edge at a phase angle of 0 °, for example, as shown in FIG. A rectangular wave having the same can be generated. Further, in the signal source 11h, the control circuit 115 performs on / off control of the switch circuit S1, and discharges the capacitor C1 charged with a constant current through the resistor R1, for example, as shown in FIG. A sawtooth wave having a falling edge at a phase angle of 0 ° can be generated.

Second Embodiment
=== Configuration of islanding detection system ===
Hereinafter, with reference to FIG. 20, the structure of the isolated operation detection system of the distributed power supply in the 2nd Embodiment of this invention is demonstrated. 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. 20, 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 of 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 FIG. 20, the relay that inputs the break command signal Sop to each breaker is not shown.

  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, the operation of the isolated operation detection system of the distributed power source in this 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. The injection signals v1 and v4 are synchronized with each other because they are synchronized with a predetermined phase of the commercial power supply.

  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. Then, the signal detection devices 109, 209, and 309 detect the components of the injection signals v1 and v4 included in the zero-phase voltage of the distribution line as the detection signal Vdt.

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, the injection signals v1 and v4 that are synchronized with each other are injected into the secondary phase zero-phase circuit of the power transformer, respectively, and each signal detector converts the components of the injection signals v1 and v4 included in the zero-phase voltage. By detecting as the detection signal Vdt, it is possible to detect the individual operation of each distributed power source. Further, when the detection signal Vdt is not detected, an isolated operation of each distributed power source is detected and disconnected from the distribution line, whereby an electric shock accident due to the isolated operation can be prevented.

  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 injection signal v <b> 1 synchronized with the predetermined phase of the commercial power supply in the secondary phase zero-phase circuit of the power transformer 2 in the distribution substation. And detecting the component of the injection signal v1 included in the zero-phase voltage of the distribution line 5 in the customer facility, thereby detecting the single operation of the distributed power supply 8 at a low cost without affecting the distribution system. Can do.

  Further, by injecting an injection signal v1 having a rising edge or a falling edge at a predetermined phase of the commercial power source, a phase difference angle with respect to the distribution substation is obtained, and detection of a reverse power flow from the distributed power source 8 to the distribution system, It can be used for controlling active power and reactive power in a power conditioner.

  Further, by generating a rectified waveform by thyristor phase control, it is possible to generate an injection signal having a rising edge or a falling edge in a phase corresponding to the firing angle.

  Further, in the thyristor phase control, the signal source of the injection signal can be configured with a small number of power electronic components by firing the thyristor according to the voltage signal (or current signal) of the phase to which the thyristor is not connected. Thus, the reliability of the isolated operation detection system for the distributed power source can be improved.

  Further, by generating a rectangular wave or a sawtooth wave as an injection signal, an injection signal having a rising edge or a falling edge at a phase angle of 0 ° or 180 ° can be generated.

  Further, in the isolated operation detection system of the distributed power source shown in FIG. 20, the injection signals v1 and v4 that are synchronized with each other are respectively injected into the secondary-side zero-phase circuit of the power transformer, and each signal detection device By detecting the components of the injection signals v1 and v4 included in the power distribution system, 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 inexpensive. Single operation can be detected.

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

  Moreover, by detecting the component of the injection signal v1 included in the zero-phase voltage of the distribution line in the customer facility, the commercial power source injected into the secondary-side zero-phase circuit of the power transformer of the distribution substation When the component of the injection signal v1 is not detected using the injection signal v1 synchronized with a predetermined phase, 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 Power transformer 3, 7 Circuit breaker 5 Distribution line 6 Relay 8 Distributed power supply 9a-9c Signal detection apparatus 11a-11h Signal source 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 93 Resistance 94 to 97 Capacitor 98 Grounded instrument transformer 101, 401 Signal injection device 102, 402 Power transformer 103 , 203, 204, 303, 304, 403 Circuit breaker 107, 207, 307 Circuit breaker 108, 208, 308 Distributed power supply 109, 209, 309 Signal detection device 111 Thyristor 112, 113 Phase control circuit 114, 115 Control circuit 1131 For instrument Transformer 1132 Diode 1133, 1134 Resistance VR1, VR2 Variable resistance T1 to T4 NPN transistor S1 Switch circuit R1 Resistance C1 Capacitor

Claims (8)

In a distribution substation that supplies power to the distribution line from the secondary side of the power transformer through the first circuit breaker , an injection signal having a rising edge or a falling edge at a predetermined phase of the commercial power supply is supplied. A signal injection device comprising: a signal source; and a first instrument transformer for transforming and injecting the injection signal into a zero-phase circuit on a secondary side of the power transformer;
In a customer facility having a distributed power source linked to the distribution line via a second circuit breaker, the consumer facility has a second instrument transformer for detecting a zero-phase voltage of the distribution line, and the zero-phase voltage A signal detection device for detecting a component of the injection signal contained in
An isolated operation detection system for a distributed power source comprising: The signal source is
A thyristor connected to any one phase of the secondary side of the power transformer;
A phase control circuit for igniting the thyristor at the predetermined phase;
The isolated operation detection system for a distributed power supply according to claim 1 , comprising: 3. The isolated operation detection of the distributed power supply according to claim 2 , wherein the phase control circuit ignites the thyristor according to a phase to which the thyristor on the secondary side of the power transformer is not connected. system. 2. The isolated operation detection system according to claim 1 , wherein the signal source supplies a rectangular wave having a rising edge or a falling edge in the predetermined phase as the injection signal. 2. The isolated operation detection system for a distributed power supply according to claim 1 , wherein the signal source supplies a sawtooth wave having a rising edge or a falling edge in the predetermined phase as the injection signal. A plurality of the signal injection devices;
The distribution line is supplied with power from the secondary side of the plurality of power transformers,
The signal injection device is islanding detection system of the distributed power supply according to any one of claims 1 to 5, characterized in that injecting each said injection signal synchronized with each other in the zero-phase circuit. The relay further includes 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 injection signal. An isolated operation detection system for a distributed power source according to any one of claims 6 to 7. In a distribution substation that supplies power to the distribution line from the secondary side of the power transformer,
Generates an injection signal having a rising edge or a falling edge at a predetermined phase of a commercial power supply;
Injecting the injection signal into the secondary phase zero-phase circuit of the power transformer,
In customer equipment having a distributed power source linked to the distribution line ,
Detecting the zero-phase voltage of the distribution line,
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 injection signal included in the zero-phase voltage is not detected.

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