JPH0833205A - Distributed power supply system interconnection system and control method therefor - Google Patents

Abstract

PURPOSE:To sustain a high operating efficiency even upon interruption of a distribution system by providing distributed power supplies connected, respectively, with a plurality of distribution lines through a switchgear, and a power supply system interconnection controller for generally controlling the switchgears. CONSTITUTION:A failure on the power supply side of a section switch 7b is detected through a protector in a distribution/transformer station and a distribution line 6b is interrupted by means of an interrupter. Consequently, the section switch 7b is opened. A voltage transformer 16b detects voltage drop of the distribution line 6b to open a power supply interconnection circuit, breaker 18b. A distributed power supply interconnection controller 17 throws in a distributed power supply system interconnection circuit breaker 18a to connect a distributed power supply 10 with a sound distribution line 6a thus interchanging the excess power temporarily. Since the distributed power supply 10 can be operated at a constant output, a high operating efficiency can be sustained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed power supply system interconnection device, and in particular, can efficiently operate a distributed power supply that is operated by being connected to a power distribution system, and is also suitable in terms of operation of the power distribution system. Distributed power supply system interconnection device.

[0002]

2. Description of the Related Art In recent years, relatively small-capacity power sources, such as photovoltaic power generation, wind power generation, fuel cells, and cogeneration, which are connected to a power distribution system to operate, so-called small-scale distributed power sources, Attention is paid to the point. Since such a small-scale distributed power source is located near the power consumption area, it has the possibility of operating as a highly efficient power system.

Such a small-scale distributed power source is disclosed in Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent Laid-Open No. 95137, it is operated in such a form that it is connected to one place of a general distribution line and exchanges electric power with the distribution line.

[0004]

However, since the power distribution system up to now has not been configured on the premise of the existence of a distributed power source, for example, in the event of a power failure of the distribution line due to an accident or the like, a power failure recovery operation of the power distribution system is performed. It is required to immediately disconnect the distributed power source from the distribution line so as not to affect the However, since the distributed power source is connected to the distribution system at one location, when the distributed power source is disconnected, excess power will be generated in the distributed power source, and the amount of power generated by the distributed power source must be reduced. Get lost. Usually, small-scale distributed generators are designed to operate most efficiently at rated output, so there is a problem that reduction in power generation directly reduces the operating efficiency of distributed generators.

Further, once the amount of power generation is once reduced, it often takes time to restart the amount of power generation again, and many distributed power sources cannot use the distributed power source when, for example, an emergency power recovery is required. There was also.

An object of the present invention is to solve the above-mentioned problems, maintain high operating efficiency of a distributed power source even during a power failure of the power distribution system, and provide a distributed power source for a power distribution system that requires power after an accident recovery operation. It is an object of the present invention to provide a distributed power system interconnection device capable of supplying electric power promptly.

[0007]

The above object is to connect a plurality of distribution lines to which power is supplied from a higher-level power system through a distribution transformer, and to connect each of the plurality of distribution lines through a switchgear. It is achieved by providing a distributed power source and a power supply interconnection control device that collectively controls each of the switching devices.

[0008]

In normal operation, only one of the plurality of switchgear connected to the distributed power source is operated in a closed state.
If the distribution line that is supplying power from the distributed power supply goes into a power failure, open the closed switchgear and then close the switchgear connected to other healthy distribution lines. And continue to supply surplus power from distributed power sources.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a power distribution system to which the distributed power system interconnection device according to the present invention is attached.

In FIG. 2, the distribution system is a distribution substation 1
A distribution transformer 2 installed in the power conversion system for converting a supply voltage from a higher power system into a distribution voltage, a circuit breaker 3 connected to the distribution transformer 2, and a three-phase bus bar connected to the circuit breaker 3. Four
And a plurality of distribution lines 6a and 6b (here, two distribution lines) connected to the three-phase bus 4 via circuit breakers 5a and 5b. Here, for example, the distribution line 6
Taking b as an example, the section switches 7a and 7b are attached to the distribution line at predetermined intervals. In addition, interconnection switches 8a, 8b, 8c, 8d that are interconnected with other distribution lines.
Will also be installed. Further, a distributed power supply device 10 is connected to the distribution line 6b via a power supply interconnection device 9. The distributed power supply device 10 is connected to the distribution lines on both sides of the interconnection switch 8c via the distributed power supply interconnection device 9. That is, in the past, the distributed power source was connected to a single distribution line via the distributed power interconnection device, whereas in the present invention, the distributed power source is distributed to a plurality of distribution lines 6a, 6b. It is configured to be connected via the interconnection device 9.

A switch or a circuit breaker in which a triangular portion or a circular portion in the symbol frame is painted black (the circuit breakers 3, 5a and 5b in the figure, the section switch 7
a, 7b, 7a ', 7b') are normally operated in a closed state (blank switch 8 in the figure).
a, 8b, 8c, 8d) indicates that the operation is performed in the open state.

Distributed power supply interconnection device 9 and distributed power supply device 1
Details of 0 will be described with reference to FIG. Distribution lines 6a, 6b
The distributed power supply interconnection lines 15a and 15b are connected to.
The distributed power interconnection lines 15a and 15b are connected to the primary sides of the instrument transformers 16a and 16b, respectively.
The secondary side of 6a and 16b are both distributed power supply interconnection control devices 1
7 is input. And the distributed power supply interconnection controller 17
Is the distributed power supply device 10 and the distributed power supply interconnection lines 15a, 1
Distributed power interconnection breaker 18 for connecting each of 5b
a and 18b are controlled.

The distributed power supply unit 10 comprises a distributed power supply 19 and internal loads 20a to 20d. Power interconnection line 1
5a, 15b and distributed power source 19 or in-house load 20a
.About.20d are connected via respective switches 21a to 21e. At present, the switches 21a, 21d and 21e are turned on.

The operating states of the distribution line and the switchgear will be described with reference to FIGS. 1 to 3. FIG. 3 is a diagram showing a state of a switchgear such as a distribution line, a switch, and a circuit breaker in a time lapse from a normal time to an accident occurrence and an emergency recovery. The switchgear is shown only as it changes due to the accident. In Fig. 3, the status of the distribution line is shown by hatching the applied power status and blank power failure status. In the case of a switchgear device, the hatching display indicates the closed state and the blank display indicates the open state.

Since the power distribution system is configured to supply power to the load with a single power distribution line for detecting an accident in the system,
The division switch 7b is closed during normal operation, and the interconnection switch 8a is closed.
Is open. In FIG. 3, the power interconnection breaker 18
It is assumed that, of the a and 18b, the power interconnection breaker 18b that is connected to the distribution line 6b is closed. It is assumed that the system is operated in this state before the accident occurrence time α.

Here, consider a case where an accident occurs on the power source side of the division switch 7b. In this case, an accident is detected by a protective device (not shown) installed in the distribution substation 1, and the distribution line 6b is cut off by the circuit breaker 5b provided at the outlet of the distribution line 6b. Become. Category switch 7
Although b is kept closed by an electromagnetic force that is in equilibrium with the force of the spring in the applied state, the electromagnetic force becomes zero when the power distribution line 6b loses power, and is opened by the spring force.

For protection of the power distribution system and safety reasons, it is decided that the distributed power source should be immediately disconnected from the power distribution line when the power distribution line is out of power. The voltage drop of the electric wire 6b is detected and the power supply interconnection breaker 18b is cut off. In FIG. 3, this state is between time α and time β. The operation up to this point is the same as the conventional one. In this way, the distributed power supply device 10 is completely cut off from the distribution line 6b. Here, the distributed power supply interconnection control device 17 of the present invention turns on the distributed power supply interconnection breaker 18a and connects the distributed power supply device 10 to the healthy distribution line 6a side to distribute the surplus power. It temporarily accommodates the electric wire 6a (between time β and time γ in FIG. 3). By doing so, the distributed power supply device 10 can be operated while maintaining a constant output.

At the next time γ, since the power is supplied from the other distribution line 6d to the load side of the distribution line 6b in the power failure state, the distributed power supply interconnection controller 17 turns on the interconnection switch 8a. At the same time, the distributed power supply interconnection switch 18a is opened and the power supply interconnection switch 18b is closed. By this processing, the portion of the distribution line 6b on the load side of the switch 7b is charged. At that time, the surplus power of the distributed power supply device 10 is also used as the interchange power, and it is possible to prevent the power outage even in the case where the power outage is conventionally caused due to the lack of the support power from the distribution line 6d.

Here, the operation and effect of the present invention have been described taking the case of an accident as an example, but the following cases are also effective in normal times. For example, it is assumed that the distribution line 6b has some power supply margin, while the distribution line 6a is overloaded. Conventionally, a part of the load of the distribution line 6a is distributed to other distribution lines by closing the interconnection switch 8c and opening any one of the division switches on the power supply side of the distribution line 6a. This procedure was complicated, and the system configuration was constantly forced to change depending on the operating state of the system.

On the other hand, in the present invention, it is possible to easily distribute the electric power simply by turning off the distributed power supply interconnection breaker 18b and turning on the distributed power supply interconnection breaker 18a. It also has the effect of eliminating the need to switch back the system.

Further, in order to prevent an excessive current due to a voltage phase difference at the time of system interconnection, a voltage transformer was conventionally provided on both sides of the interconnection switch 8c to check the voltage. The dual use of 16a and 16b also has the effect of eliminating the need for a conventional instrument transformer.

[0022]

As described above, according to the present invention, a plurality of distribution lines supplied with electric power from the upper power system via the distribution transformer, and a switchgear for each of the plurality of distribution lines. Even if there is a power failure in the distribution line that the distributed power supply supplies, the distributed power supply connected via the Since the mold power source is connected to another distribution line, high efficiency can be maintained without lowering the operating efficiency of the distributed power source. In addition, even during an accident recovery operation, there is an effect that power can be quickly supplied from the distributed power source to the distribution line that is out of power.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a distributed power system interconnection device according to the present invention.

FIG. 2 is a power distribution system diagram to which the distributed power system interconnection device shown in FIG. 1 is applied.

FIG. 3 is a time chart showing operating states of the distribution line and the switchgear shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Distribution substation, 2 ... Distribution transformers, 6a, 6b ... Distribution lines, 9 ... Power interconnection device, 10 ... Distributed power supply device, 15
a, 15b ... Power source interconnection line, 16a, 16b ... Instrument transformer, 17 ... Power source interconnection control device, 18a, 18b ... Power source interconnection switch, 19 ... Distributed power source.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Pan Inoue 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture Hitachi Ltd. Omika factory

Claims (5)

[Claims] 1. A plurality of distribution lines to which power is supplied from a higher-level power system via a distribution transformer, a distributed power source connected to each of the plurality of distribution lines via a switchgear, and the switchgear. A distributed power supply system interconnection device comprising a distributed power supply interconnection control device for collectively controlling each of the above. 2. A plurality of distribution lines composed of a plurality of division switches, wherein electric power is supplied to the distribution lines from a higher power system via a circuit breaker, and the division switches and other distribution lines are provided. A distributed power supply connected to both ends of the divisional switch or the interconnection switch connecting the circuit breaker via switchgear, and a distributed power supply interconnection controller for collectively controlling each of the switchgear. A distributed power system interconnection device characterized in that 3. The instrument transformer according to claim 1, further comprising an instrument transformer for detecting an operating state of a system to which the distributed power supply interconnection control device is connected, and responding to an output of the instrument transformer. A distributed power system interconnection device, characterized in that the switching state of the switchgear is switched. 4. A distributed power system in which electric power is supplied from a higher power system to a plurality of distribution lines via a distribution transformer, and a distributed power source is connected to each of the plurality of distribution lines via a switchgear. In the interconnection control method, the power supply of the distributed power source is switched to another distribution line in response to the power supply interruption of the distribution line supplying power from the distributed power source. Power system interconnection control method. 5. A distributed power system in which electric power is supplied from a higher-level power system to a plurality of distribution lines via a distribution transformer, and a distributed power source is connected to each of the plurality of distribution lines via a switchgear. In the interconnection control method, the distributed power system interconnection control method is characterized in that the power supply of the distributed power source is switched in response to a load state of the distribution line to which the distributed power source is connected.