JPH0479215B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a protection circuit for a power system equipped with a solar cell power generation system.

[Prior art and its problems]

In recent years, research on solar cells has progressed rapidly, and many are now in practical use. Generally, the output that a single solar cell can generate is small compared to existing power grids, so when connecting solar cells to the power grid, 3KV or 6KV distribution lines are the target.

BACKGROUND ART Conventionally, as a method of incorporating a solar cell power generation system into a power distribution line, for example, a circuit configured as shown in FIG. 1 is known. That is, in FIG. 1, reference numeral 10 indicates a power distribution substation;
Equipped with 3KV or 6KV power supply line. From the substation 10, a distribution line 14 is connected via a sending circuit breaker 12.
is derived, and a load 18 is connected to this distribution line 14 via a customer-side circuit breaker 16.

In this case, the consumer distribution line 20 to which the load 18 is connected is connected to the solar cell 28 via a solar cell circuit breaker 22, a step-up transformer 24, and an inverter 26.
are connected to form a solar cell power generation system. Note that a reverse transmission relay 32 is connected via a current transformer 30 between the connection point of the solar cell power generation system configured in this manner to the customer power distribution line 20 and the customer side circuit breaker 16 . Furthermore, for a distribution line load 36 that is directly connected to the distribution line 14 via a load circuit breaker 34, a solar battery 44 is connected to the distribution line 14 via a solar battery circuit breaker 38, a step-up transformer 40, and an inverter 42. A solar cell power generation system is constructed by connecting them.

In the solar cell power generation system configured in this manner, the power generated by the solar cells 28 and 44 is supplied to the loads 18 and 36 together with the power supplied from the distribution line 14. Therefore, if the outgoing circuit breaker 12 is currently disconnected, this condition can be quickly detected, the customer side circuit breaker 16 is shut off, and the load 18 can be operated independently by the solar cell power generation system. required. In this case, in the conventional circuit configuration shown in FIG. 16 is released.

However, when the solar cell power generation system is constantly operating, the reverse transmission relay 32
cannot function as a detector for the customer-side circuit breaker 16. Further, in a solar cell power generation system directly connected to the power distribution line 14, it is difficult to employ the detection method using the reverse transmission relay 32 described above. Furthermore, if a short circuit or the like occurs in the power distribution system, there is a possibility of malfunction.

In particular, if the sending circuit breaker 12 trips or the entire distribution substation 10 experiences a power outage,
If this state cannot be detected reliably, the entire load on the distribution line 14 may be removed from the solar cell power generation system, and there is a possibility that an unreliable voltage may remain, which has the drawback of adversely affecting the load. That is, solar cells generally have a large internal impedance, making it difficult for overload and overcurrent relays to operate, especially in a light-shielded state.

[Purpose of the invention]

The present invention provides a solar power generation system connected to a power distribution system that properly performs the detection operation necessary for independent operation of the solar power generation system in the event of a power outage in the power distribution system, thereby protecting the power distribution system and improving the power supply to the load. The object of the present invention is to provide a protection circuit for a power system including solar cells that can be achieved.

[Key points of the invention]

The present invention provides a customer-side circuit breaker for a power system that supplies power to all loads through a distribution line led out from a distribution substation via a sending-out circuit breaker, and provides a customer-side circuit breaker. A predetermined load is connected to the customer distribution line branched out through the equipment, and
In a protection circuit for a power system equipped with a solar battery power generation system consisting of a solar battery circuit breaker, a step-up transformer, an inverter, and a solar cell, so as to be able to independently supply power to the consumer distribution line in the event of a power outage in the power system. , An undervoltage relay is installed on the distribution line leading from the substation via an instrument transformer, and when the undervoltage state of the power system continues for a certain period of time, the undervoltage relay reduces the power including the solar cell system. Further, a circuit breaker is provided to cut off the grid from the power system for all loads, and the capacity of a predetermined load connected to the consumer distribution line that is independently supplied with power by the solar battery power generation system is set to It is characterized in that it is configured to selectively shut down until it matches the power generation output.

That is, in the present invention, when switching to independent power supply by the solar cell power generation system for a predetermined load in the event of a power outage in the power system, an undervoltage relay is provided in a part of the power system for all loads to detect a voltage reduction state, When this undervoltage condition continues for a certain period of time, the power system between the specified load and the solar power generation system is cut off from the power system for all loads, and the capacity of the load that is solely powered by the solar power generation system is changed to the solar power generation system. By configuring the system to selectively cut off the power until it matches the power generation output of the system, it is possible to continue supplying power appropriately and stably to the necessary load.

[Embodiments of the invention]

Next, embodiments of a protection circuit for a power system equipped with a solar cell power generation system according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a power distribution system diagram showing an embodiment of the circuit of the present invention. In other words, this example circuit shows a case where a solar cell power generation system is connected to a consumer distribution line branched from a part of the distribution line, and its basic circuit configuration is the same as the circuit shown in FIG. are the same. Therefore, for convenience of explanation, the same reference numerals are given to the same components as those in the circuit shown in FIG. 1, and detailed explanation thereof will be omitted.

That is, in the present invention, the customer power distribution line 2 is branched out via the customer side circuit breaker 16 from the power distribution line 14 to which the solar cell power generation system is connected.
0, the load 18 is connected via a circuit breaker 46 as appropriate without providing a reverse power transmitter. Therefore,
In the present invention, instead of the conventional reverse transmission relay,
This system is characterized in that an undervoltage relay 52 is provided to the power distribution line 14 via a voltage transformer 50. In this case, it is preferable that the potential transformer 50 be provided, for example, on the distribution line load 36 side, rather than on the output circuit breaker 12 side provided with respect to the distribution substation 10.

Next, the operation of the circuit of the present invention having the above configuration will be explained. If an accident or power outage occurs in the power distribution system, a voltage drop will occur in the power distribution line 14 connected to the load 36. Therefore, this voltage drop activates the undervoltage relay 52 via the potential transformer 50 if it continues for a certain period of time. Next, the consumer circuit breaker 16 is cut off based on the operation of the power shortage relay 52, and the independent power supply to the load 18 is continued by the solar cell power generation system. In this case, if the capacity of the load 18 is larger than the output of the solar cell power generation system, the capacity of the load 18 connected to the consumer distribution line 20 is selectively cut off and reduced until it matches the power generation output of the solar cell 28. It is suitable if

[Effects of the Invention] As is clear from the embodiments described above, according to the present invention, in the power system to which the solar power generation system is connected, the solar power generation system can independently supply power to a predetermined load in the event of a power outage in the power system. In the case of switching, an undervoltage relay is installed to detect a voltage reduction state in the power system for all loads, and when the undervoltage state continues for a certain period of time, the power system that connects the solar power generation system and the specified load is installed. By configuring the circuit breaker provided at the connection point with another power system to shut off, it is possible to appropriately continue supplying power to a predetermined load by the solar cell power generation system.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a configuration example of a power system equipped with a conventional solar power generation system, and Fig. 2 is a power system diagram equipped with a solar power generation system showing an example of a protection circuit according to the present invention. It is. 10... Distribution substation, 12... Outgoing circuit breaker, 14... Distribution line, 16... Customer side circuit breaker,
18...Load, 20...Customer distribution line, 22...
Solar cell circuit breaker, 24...Step-up transformer, 26
... Inverter, 28 ... Solar cell, 34 ... Load circuit breaker, 36 ... Distribution line load, 46 ... Circuit breaker, 50 ... Instrument transformer, 52 ... Undervoltage relay.

Claims (1)

[Scope of Claims] 1. A customer-side circuit breaker is provided for a power system that supplies power to all loads through a distribution line led out from a distribution substation via a sending circuit breaker, A solar battery circuit breaker is provided so that a predetermined load is connected to the consumer distribution line branched out through the house-side circuit breaker, and at the same time, power can be supplied independently to the consumer distribution line in the event of a power outage in the power system. , in a protection circuit for a power system equipped with a solar power generation system consisting of a step-up transformer, an inverter, and a solar cell, an undervoltage relay is provided on the distribution line leading out from the substation via a voltage transformer, and this Further, a circuit breaker is provided that cuts off the power system including the solar cell system from the power system serving the entire load when the undervoltage state of the power system is intermittent for a certain period of time due to an undervoltage relay, and the solar cell power generation system independently A solar cell power generation system characterized in that the capacity of a predetermined load connected to the consumer distribution line to which power is supplied is selectively cut off until it matches the power generation output of the solar cell power generation system. Power system protection circuit.