JP2017195775A - Individual operation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an individual operation of a dispersion type power source at a high speed, and parallel off a plurality of dispersion type power sources.SOLUTION: A second individual operation detection device 140b comprises: a fluctuation generation part 142 which not include a whole plurality of dispersion type power sources including the dispersion type power source connected to a first individual operation detection device 140a that requires to parallel off a dispersion type power source 130 that is communicated with a commercial power system 110 and is belonged to a predetermined connection range for 0.5 seconds to 1.0 seconds; and a parallel-off processing part 144 that detects fluctuation of a predetermined electric parameter at a system interconnection point, and parallel offs the plurality of dispersion type power sources from a commercial power system by less than 0.5 seconds through a plurality of breakers 150 connecting the plurality of dispersion type power sources with the system interconnection point or outputs an individual operation signal stopping the plurality of dispersion type power source by less than 0.5 seconds when the predetermined electric parameter exceeds a threshold value and is fluctuated applied by the fluctuation generation part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an isolated operation detection device that detects that a distributed power source connected to a commercial power system has been operated independently.

  In recent years, distributed power sources such as photovoltaic power generation facilities have been connected to loads managed by customers, and the power of the distributed power sources is used to cover the load, and the distributed power source and the commercial power system are linked together. When the generated power is less than the power consumed by the load, grid interconnection is performed to receive the insufficient power from the commercial power system. Further, in a grid-connected distributed power source, when the generated power is larger than the power consumed by the load, power can be supplied (reverse power flow) from the distributed power source to the commercial power system for sale.

  Under such system interconnection, when the supply of power from the commercial power system side stops due to a power failure or the like on the commercial power system side, the power of all loads connected to the distributed power source, including the load managed by the customer This is a stand-alone operation that is covered only by a distributed power source In isolated operation, there is a risk of overloading the distributed power source, and reverse charging from the distributed power source to the commercial power system may cause electric shock or damage to consumer equipment. For this reason, an isolated operation detection device that detects isolated operation and disconnects the distributed power source from the commercial power system may be provided.

  An active method is known as a method in which the single operation detection device detects single operation. In the active method, a small change is given to electrical parameters such as voltage and frequency at the output of the distributed power source, and the single operation is determined by utilizing the increase in the change during the single operation. As the active method, for example, a conventional active method such as a frequency shift method, an active power fluctuation method, a reactive power fluctuation method, or the like is used. In a predetermined range (connection range) in which a plurality of distributed power sources such as an apartment are connected to each other and the power of the connected plurality of distributed power sources is jointly used (conventional active method) There is known a technique in which the single operation detection device of No. 1 gives fluctuations to the outputs of all of the plurality of distributed power sources (for example, Patent Document 1). In addition, the single active operation detection device of the conventional active method gives fluctuations to the outputs of all of the plurality of distributed power sources, and the single active operation detection device of the conventional active method supplies a plurality of distributed power sources during single operation. A technique for disconnecting is known (for example, Patent Document 2).

Japanese Patent No. 3408004 JP 2000-236629 A

  In recent years, a new type active type (new type active type) islanding detection device has been developed. In the conventional active method, the time period from the occurrence of isolated operation to the disconnection of the distributed power source is defined as 0.5 to 1.0 seconds, but in the new active method, the distributed power source is set to 0.5 seconds. It can be disconnected at high speed in less than a second. An example of such a new active method is a frequency feedback method with step injection.

  When such a new active type islanding detection device is newly installed together with a distributed power source, a conventional active type islanding detection device is still connected in the connection range, and a new active type islanding detection device is used. And a conventional active type isolated operation detector may be mixed.

  In the new type active system, the distributed power source can be disconnected at high speed, so that all of the connection range of the new active type is not used by the new type active type islanding detection device. It can be considered that the distributed power supply is disconnected at high speed. However, since the technologies of Patent Documents 1 and 2 are based on the premise that one single operation detection device gives fluctuations to all of the plurality of distributed power sources, in order to disconnect all the distributed power sources in the connection range. Therefore, it is necessary to modify the existing distributed power supply so that the output of all the distributed power supplies fluctuates according to the signal from the new active type isolated operation detection device. Moreover, since the technique of patent document 2 is a technique limited to a synchronous generator, it could not be applied to a distributed power source using a power conditioner such as a solar power generation facility.

  Therefore, in view of such a problem, the present invention has an object to provide an isolated operation detection device that can detect isolated operation of a distributed power supply at high speed and disconnect a plurality of distributed power supplies. Yes.

  In order to solve the above-mentioned problem, the isolated operation detection device of the present invention is connected to a commercial power system and belongs to a predetermined connection range. A variation generator for varying the output of at least one distributed power source that does not include all of the plurality of distributed power sources including the distributed power source connected to another isolated operation detection device that requires seconds, and a predetermined at the grid connection point When a predetermined electrical parameter fluctuates beyond a threshold value due to fluctuation given by the fluctuation generator, a plurality of circuit breakers connecting a plurality of distributed power sources and grid interconnection points are used. A discontinuous processing unit that disconnects the distributed power source from the commercial power system in less than 0.5 seconds or outputs a single operation signal for stopping a plurality of distributed power sources in less than 0.5 seconds. It is characterized by that.

  According to the present invention, it is possible to detect a single operation of a distributed power source at a high speed and disconnect a plurality of distributed power sources.

It is a figure for demonstrating the state by which the some distributed power source was connected with the commercial power grid. It is a figure for demonstrating the flow of time from the generation | occurrence | production time of a high-low pressure contact accident until it decouples a distributed power source. It is a figure for demonstrating the fluctuation | variation of the output of the distributed power supply at the time of a single operation in the frequency feedback system with step injection. It is a figure for demonstrating the independent operation detection system concerning a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram for explaining a state in which a plurality of distributed power sources 130 are connected to the commercial power system 110. As shown in FIG. 1, the commercial power system 110 includes a system power source 112, a circuit breaker 114, and a distribution line 116. The system power source 112 corresponds to, for example, a power plant of an electric power company, and the power generated by the system power source 112 is supplied to the house 120a and the house 120b connected to the distribution line 116 by the distribution line 116 via the circuit breaker 114. Here, it is assumed that the distributed power source 130 is provided in the house 120a and the distributed power source 130 is not provided in the house 120b. Therefore, the load 122 of the house 120b is covered by the power of the system power supply 112 supplied via the circuit breaker 124.

  The islanding operation detection system 100 includes a distributed power source 130, a load 132, an islanding operation detection device 140, and circuit breakers 150 and 160. In the present embodiment, the predetermined range (connection range) in which the power of the distributed power source 130 is shared is the house 120a. The house 120a is, for example, an apartment house such as an apartment, and the distributed power source 130 is interconnected in each of a plurality of apartments (3 in this embodiment).

  The distributed power source 130 includes, for example, a solar cell, a fuel cell, an engine generator, and the like. The distributed power source 130 generates power, supplies the generated power to the load 132, and connects the generated power to commercial power. Supply (reverse power flow) to the system 110 side is possible. The distributed power supply 130 is connected to the isolated operation detection device 140. Here, the distributed type power supply 130a connected to the conventional active type isolated operation detection device (hereinafter referred to as "first isolated operation detection device") 140a is replaced with the distributed type power supply 130a, and the new active type isolated operation detection device. The distributed power source 130 connected to 140b (hereinafter referred to as “second isolated operation detection device”) is referred to as a distributed power source 130b.

  The first islanding operation detection device 140a varies in electrical parameters such as voltage and frequency at the output of the distributed power source 130a by a conventional active method (eg, frequency shift method, active power fluctuation method, reactive power fluctuation method, etc.). And the isolated operation of the distributed power source 130a is detected. The second isolated operation detection device 140b detects the isolated operation of the distributed power source 130b by a new active method (for example, a frequency feedback method with step injection). The new active system is an active system newly developed compared with the conventional active system, and can distribute the distributed power source 130 at a higher speed than the conventional active system. Note that when the distributed power source 130 is connected to the grid, it is necessary to install the isolated operation detection device 140. Therefore, the distributed power source 130a is provided with the first isolated operation detection device 140a. In such an isolated operation detection system 100, since the second isolated operation detection device 140b is used, the first isolated operation detection device 140a is not used.

  Next, the speed from the occurrence of an isolated operation to the disconnection of the distributed power source 130 (130a, 130b) in the first isolated operation detection device 140a and the second isolated operation detection device 140b will be described.

  For example, when the power capacity of the distributed power source 130 is less than 50 kW and is connected to a low voltage, the time required from the time of occurrence of the high / low pressure accident to the time of disconnecting the distributed power source 130 as a countermeasure for the high / low pressure accident (For example, 1.0 second) is defined in the grid interconnection regulations.

  FIG. 2 is a diagram for explaining the flow of time from the time of occurrence of a high / low pressure mixed accident until the distributed power supply 130 is disconnected. As shown in FIG. 2, it is general from the occurrence of a high / low pressure contact accident (time T0) to the disconnection of the system power source 112, that is, the release of the circuit breaker 114 (see FIG. 1) on the system power source 112 side (time T1). Takes about 0.5 to 0.9 seconds. Then, from the time T1 when the circuit breaker 114 is released, the distributed power source 130 becomes an independent operation. Therefore, the first islanding operation detection device 140a and the second islanding operation detection device 140b disconnect the distributed power source 130a and the distributed power source 130b in about 0 to 0.5 seconds after the occurrence of the individual operation (time point T1). It is necessary to release the circuit breaker 150 (time T2).

  However, in the first isolated operation detection device 140a that is a conventional active method, the time period from the occurrence of isolated operation (time T1) to the release of the circuit breaker 150 (time T2) is defined as 0.5 to 1.0 seconds. ing. On the other hand, in the second isolated operation detection device 140b which is a new active method, the circuit breaker 150 is released at a higher speed than the first isolated operation detection device 140a in less than 0.5 seconds from the occurrence of the isolated operation (time point T1). be able to. For this reason, even if the first islanding operation detection device 140a cannot connect to the grid because it spends more time than the specified time, the second islanding operation detection device 140b can be connected to the grid in a short time. Can be used.

  Next, in the islanding operation detection system 100 according to the present embodiment, a configuration in which the second islanding operation detection device 140b disconnects the distributed power sources 130 (130a and 130b) will be described.

  Returning to FIG. 1, the second islanding operation detection device 140 b includes a fluctuation generation unit 142 and a disconnection processing unit 144. The fluctuation generation unit 142 detects an electrical parameter (for example, a frequency in the frequency feedback method with step injection) at the grid connection point that is a connection point between the distributed power source 130 and the distribution line 116 through the input line L1. Then, according to the detected frequency, the fluctuation generation unit 142 injects an electrical parameter (for example, reactive power in the case of the frequency feedback method with step injection) into the output of the distributed power supply 130b so as to promote the fluctuation of the frequency. An active signal is always transmitted through the output line M. The disconnection processing unit 144 detects the frequency at the grid connection point through the input line L2. When the frequency variation detected by the disconnection processing unit 144 exceeds a predetermined threshold, the disconnection processing unit 144 outputs a single operation signal to the circuit breaker 150 through the output lines N1, N2, and N3. 150 is released. As a result, the distributed power source 130 (130a, 130b) is disconnected. In this embodiment, the fluctuation generation unit 142 detects the frequency through the input line L1 and the disconnection processing unit 144 detects the frequency through the input line L2. However, the configuration for detecting the frequency is a common configuration. You can also.

  FIG. 3 is a diagram for explaining fluctuations in the output of the distributed power supply 130b during single operation in the frequency feedback method with step injection, and FIG. 3A shows the invalidity in the output of the distributed power supply 130b on the vertical axis. FIG. 3 is a diagram showing power Q (var), the horizontal axis indicating time t (s), FIG. 3B is the frequency f (Hz) at the output of the distributed power source 130b, and the horizontal axis is time t (s). ).

  As described above, in the second isolated operation detection device 140b that employs the frequency feedback method with step injection, the active signal is always transmitted and reactive power is injected into the output of the distributed power source 130b. However, as shown in FIG. 3A, the variation in reactive power at the output of the distributed power source 130b is small from the time T0 when the high / low pressure accident occurs until the time T1 when the distributed power source 130b is operated independently. Therefore, as shown in FIG. 3 (b), the variation in frequency at the output of the distributed power supply 130b is also reduced until time T1. This is because reactive power fluctuations at the output of the distributed power supply 130b are absorbed by the system power supply 112 side.

  When the distributed power source 130b is in an isolated operation (time point T1), the injected reactive power is not absorbed by the system power source 112, so the reactive power injected by the second isolated operation detection device 140b causes the distributed power source 130b to The reactive power fluctuations at the output increase (FIG. 3A). Then, the fluctuation of the frequency increases with the fluctuation of the reactive power at the output of the distributed power source 130b (FIG. 3B). When the frequency variation reaches a predetermined threshold value H1 (time point Th1), reactive power is injected more rapidly into the output of the distributed power source 130b by the second islanding operation detection device 140b, and the frequency variation. Is promoted. As a result, when the frequency fluctuation reaches a predetermined threshold value H2 (time point Th2), the second islanding operation detection device 140b disconnects the distributed power source 130 (time point T2). In FIG. 3, for ease of understanding, the time Th2 and the time T2 are illustrated with a gap between them, but the second islanding operation detection device 140b instantaneously disperses after the frequency reaches the threshold value H2. In order to disconnect the mold power supply 130, the time point Th2 and the time point T2 are substantially the same.

  When the second islanding operation detection device 140b is newly installed together with the distributed power supply 130b, the first islanding operation detection device 140a and the second islanding operation detection device 140b may be mixed in the connection range as shown in FIG. According to the islanding operation detection system 100 according to the present embodiment, the distributed power source 130a can be disconnected at high speed by the second islanding operation detection device 140b without modifying the first islanding operation detection device 140a. Become.

  Further, as described above, it is difficult for the first isolated operation detection device 140a to disconnect the distributed power source 130a from the distribution line 116 within a predetermined time (for example, 1.0 second), and the grid interconnection (Low-pressure interconnection). According to the isolated operation detection system 100 according to the present embodiment, a plurality of distributed power sources 130 (130a, 130b) can be disconnected at high speed by one second isolated operation detection device 140b. In the detection device 140a, even if the distributed power source 130a that could not be connected to the system (low voltage connection) because it took more than a specified time from the occurrence of the isolated operation to the detection, the second independent It is possible to perform grid interconnection without providing the operation detection device 140b.

  Furthermore, according to the isolated operation detection system 100 according to the present embodiment, the distributed power source 130 can be used not only for a synchronous generator but also for a photovoltaic power generation facility provided with a power conditioner.

  Moreover, when the power capacity of the distributed power source 130 is 50 kW or higher and a high-voltage connection is made, it is necessary to provide a ground fault overvoltage relay (OVGR) in order to detect a ground fault. However, since the isolated operation detection system 100 according to the present embodiment can detect the isolated operation at a high speed, the OVGR can be omitted, and the cost required for the OVGR can be reduced.

(Modification)
FIG. 4 is a diagram for explaining an isolated operation detection system 200 according to a modification. Note that components having substantially the same functions as the components of the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The isolated operation detection system 200 includes a distributed power supply 130, a load 132, a second isolated operation detection device 140b, and a circuit breaker 160. The disconnection processing unit 144 of the second isolated operation detection device 140b in the isolated operation detection system 200 outputs an isolated operation signal to the circuit breaker 160 through the output line N4, and releases the circuit breaker 160. Since the circuit breaker 160 is located upstream of the three circuit breakers 150 (system power supply 112 side), all the distributed power supplies 130 in the connection range are disconnected by releasing only the circuit breaker 160. It becomes.

  Therefore, even in the isolated operation detection system 200 according to the modification, the three distributed power sources 130 can be disconnected at high speed by the first isolated operation detection device 140b without modifying the first isolated operation detection device 140a. Is possible.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiments and modifications, the second islanding operation detection device 140b employs a frequency feedback method with step injection. However, the second islanding operation detection device 140b is a new active system and can be an islanding operation detection device capable of disconnecting the distributed power source 130 in less than 0.5 seconds after the system power source 112 is disconnected. That's fine.

  In the above-described embodiment and modification, the second islanding operation detection device 140b disconnects the distributed power source 130 from the distribution line 116 by releasing the circuit breakers 150 and 160. However, when the distributed power source 130 includes an inverter, the second islanding operation detection device 140b may stop the output of the inverter by the gate block.

  INDUSTRIAL APPLICABILITY The present invention can be used for an isolated operation detection device that detects that a distributed power source linked to a commercial power system has been operated independently.

100, 200 Isolated operation detection system 110 Commercial power system 130 Distributed power source 140b Second isolated operation detection device (single operation detection device)
142 Fluctuation generator 144 Dissolution processor

Claims (1)

A distributed power source connected to another isolated operation detection device that is connected to a commercial power system and belongs to a predetermined connection range and requires 0.5 to 1.0 seconds until the distributed power source is disconnected. A fluctuation generating unit that fluctuates the output of at least one distributed power supply that does not include all of the plurality of distributed power supplies including;
When a change in a predetermined electrical parameter at a grid connection point is detected and the predetermined electrical parameter fluctuates beyond a threshold due to the fluctuation given by the fluctuation generation unit, the plurality of distributed power sources and the grid connection are Disconnect the plurality of distributed power sources from the commercial power system in less than 0.5 seconds through a plurality of circuit breakers connecting the system points, or stop the plurality of distributed power sources in less than 0.5 seconds A disconnection processing unit for outputting a single operation signal;
An isolated operation detection device comprising:

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