JPS63314135A - Receiving end protective device - Google Patents

Abstract

PURPOSE:To prevent an unwanted action due to power fluctuation at the time of a customer's premises accident by constituting an apparatus so that a reverse power detection relay operates only when a transmission capacity detection circuit operates but a power fluctuation detection circuit does not. CONSTITUTION:A power fluctuation due to a customer's premises accident is detected by a power fluctuation detection circuit 10. A power converter 13 for said power fluctuation detection circuit 10 detects a demanded power; and when an alarm setter 14 detects that said demanded power exceeds a certain value, a time limit relay 15 gives a contact output after a certain time interval. When a transmission capacity detection circuit 9 operates and the power fluctuation detection circuit 10 also operates at the same time, the output of said transmission capacity detection circuit 9 is blocked for a certain period of time and a parallel-off command is not given. When the power fluctuation detection circuit 10 does not operate on the contrary, a circuit breaker 2 is cut off from the parallel connection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power receiving end protection device when a private power generation system and a power receiving system are operated in parallel.

[Conventional technology]

FIG. 2 is a circuit diagram showing an example of a conventional power receiving end protection device. In the figure, 1 is a power company system, 2 is a power receiving circuit breaker, 3 is a voltage current transformer, 4 is a voltage transformer, 5a is provided to receive signals from the instrument current transformer 3 and the instrument transformer 4, detect reverse transmission of power from the customer premises system to the power company system, and disconnect the power receiving breaker 2. 6 is a private generator, 7 is consumer load equipment, and 8 is a time-limited relay.

Conventional power receiving end protection devices are configured in this way and can be damaged.
Generally, when the electric power company system 1 and the private generator 6 operate in parallel, one company sends a request to the customer in order to prevent the impact of an accident or operational malfunction from affecting the electric power company or other customers. It is required to be able to automatically open the power receiving circuit breaker 2 when a consumer's power reception is punctured and the power is reversed.

For this reason, a reverse power detection relay 5a is installed for the purpose of detecting reverse power transfer in the power receiving bank, and its operation will be explained next.

If the output of the private generator 6 exceeds the power of the customer load equipment 7 for some reason, the power will be sent back from the customer's premises system to the Simi power company system 1. When this reverse power transmission exceeds a certain value, the reverse power detection relay 5a detects the current signal at the receiving point from the instrument current transformer 3 and the voltage signal at the receiving point from the instrument transformer 4, The power receiving circuit breaker 2 is disconnected from the line.

[Problem that the invention seeks to solve]

The conventional power receiving end protection device is configured as described above, and because the reverse power detection relay 5a detects the instantaneous value of reverse power and operates, it prevents short-term reverse transmission caused by power fluctuations in the event of an accident on the customer's premises. The problem has been that even the power receiving circuit breaker 2 is disconnected from the line.

As a result, the private generator 6 has to operate independently, and it becomes necessary to stop the operation of the load equivalent to the purchased power that was supplied from the electric power company system 1 during normal operation. If you do not stop it, the private generator 6 will be overloaded.
There is a risk of total power outage to the customer's premises system. For this reason, it is unavoidable to provide an external time-limited relay 8 to delay disconnection for a certain period of time so that it will not operate due to instantaneous power fluctuations.

Furthermore, in order to restore the electric power company system 1 and the private generator 6 to the parallel operation state, there was a problem in that the power reception breaker 2 had to be reinserted.

This invention was made in order to solve the above-mentioned problems.In the case of reverse transmission caused by power fluctuation due to an accident on the customer's premises, it will not operate, and in the case of reverse transmission that does not have the above-mentioned fluctuation phenomenon. The objective is to obtain a power receiving end protection device that operates instantaneously.

[Means for solving problems]

The power receiving end protection device according to the present invention includes a reverse power detection circuit that detects reverse power transmission, and a reverse power detection circuit that detects reverse power transmission. It consists of a power fluctuation detection circuit that stops the train.

[For production]

The power receiving end protection device of the present invention detects power fluctuations in the event of an accident on a customer's premises, and even if the reverse power detection circuit operates, if the power fluctuation detection circuit operates, a disconnection signal of the power receiving breaker is sent. This was done so that it would not be emitted.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a circuit diagram showing a private power generation system protection device. In FIG. 1, the same components as those in FIG. 2 are given the same reference numerals, and their explanations are omitted. In the figure, 9 is a reverse power detection circuit, and 10 is a power fluctuation detection circuit that detects the power fluctuation shown in FIG. 3 in which the power value once increases in the positive direction and then exceeds the set value in the negative direction. The reverse power detection circuit 9 and the power fluctuation detection circuit 10 constitute a υ reverse power detection relay 5b. 11 is an AND gate, 12 is a NOT gate, 13 is a power converter, 14 is an alarm setting device, and 15 is a time relay. The power fluctuation detection circuit 10 includes a power converter 13 that converts the purchased power into a corresponding signal level, and detects that the output from the power converter 13, that is, the purchased power exceeds a certain value, and sends a contact signal. It consists of an alarm setting device 14 that outputs an alarm setting device 14, and a time-limited relay 15 that outputs a flk'VC contact output for a fixed period of time based on the output of the alarm setting device 14.

Figure 3 is a graph showing an example of power fluctuations due to an accident within a customer's premises, and Figure 4 is a graph showing an example of power fluctuations from the customer premises to the power company grid that are not caused by power fluctuations.
It is a graph diagram showing an example of the power (K
The positive direction of the W) axis indicates the received power 17 in which the power direction is from the power company system 1 to the consumer side, and the negative direction indicates the power is directed from the consumer side to the power company system, that is, a reverse transmission state.

Next, the operation will be explained. The power fluctuation due to an accident within the customer's premises is detected by the power fluctuation detection circuit 10, which detects an increase in the received power as shown in FIG. This power fluctuation detection circuit 10 converts the purchased power into a corresponding signal level using a power converter 13, and an alarm setting device 1 detects that the purchased power exceeds a certain value.
4 is detected, the time-limited relay 15 outputs a contact output after a certain period of time. Accordingly, if the power purchased from the power company grid at the power receiving point exceeds a certain value, the time-limited relay 15
(This time is determined by the time it takes for the purchased power to increase due to power fluctuations caused by an on-site accident, and then to return to a steady state (usually within 1 second)) blocks the line disconnection signal of the power reception breaker 2.

In addition, the current value and voltage value at the power receiving point are inputted to the reverse power detection circuit 9 via the instrument current transformer 3 and the instrument transformer 4, respectively.
When a constant reverse power value 16 is detected, the output of the reverse power detection circuit 9 is output.

Here, even if the reverse power detection circuit 9 operates, if the power fluctuation projection circuit 10 operates at the same time, that is, in the case of the reverse power transmission 18 shown in FIG. If the output is blocked and a disconnection command is not issued, and if the power fluctuation detection circuit 10 is inoperative, that is, if the power is reversely transmitted as shown in FIG. 4, the power receiving breaker 2 is disconnected. .

In the above embodiment, a reverse power detection relay that determines an accident on a customer's premises by detecting an overcurrent from the electric power company system 1 at a power receiving point is shown, but the present invention is not limited to this. For example, a method of detecting an increase in purchased power from power company system 1, a method of integrating fluctuations in purchased power, and determining that this is not decreasing, etc.
It can be applied to any method of determining power fluctuations as shown in FIG. 3, and provides the same effects as the above embodiment.

〔Effect of the invention〕

As described above, according to the present invention, since the reverse power detection relay is configured to operate only when the reverse power detection circuit is activated and the power fluctuation detection circuit is not activated, Unnecessary operations can be prevented, and the effect is that it is possible to continue parallel operation of the electric power company system and the customer premises system without providing an external time-limited relay.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a power receiving end protection device according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing an example of a conventional power receiving end protection device, and Fig. 3 is a circuit diagram showing a power receiving end protection device according to an embodiment of the present invention. FIG. 4 is a power fluctuation curve diagram showing an example of the power fluctuation. FIG. 4 is a power reversal curve diagram representing an example of the power being sent back to the electric power company system without the above-mentioned power fluctuation. 1 is a power company system, 2 is a power reception breaker, 5b is a reverse power detection relay, 9 is a reverse power detection circuit, and 10 is a power fluctuation detection circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation 1; power company system also shown in Figure 2

Claims (1)

[Claims] A reverse power detection relay was installed to detect the reverse transmission of power from the customer's premises system to the power company grid, and to disconnect the disconnection of power from the consumer's premises system, which has a private power generation equipment that operates in parallel with the power company grid at all times. In the power receiving end protection device, the reverse power detection relay includes a reverse power detection circuit that detects reverse transmission of power, and a reverse power detection relay that detects reverse power transmission when the power fluctuation is a pulsation that exceeds a set value due to the above customer premises system fault. A power receiving end protection device comprising: a power fluctuation detection circuit that stops disconnection of disconnectors.