JPH0446528A - Automatic load selecting breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention minimizes the amount of load that is automatically selected and cut off when a generator breaker trips during parallel operation between an electric power company and a private power generation facility. This invention relates to an automatic load selection cutoff device that controls the load so that

[Conventional technology]

A conventional device of this type is shown in FIG.

In the figure, 1 is a power receiving breaker that receives power purchased by the electric power company, 2 is a power receiving transformer, 3 is a power receiving secondary breaker installed on the secondary side of the power receiving transformer 20, and 4 is a generator breaker for private power generation equipment. , 5 is the generator, 6 is an in-station load breaker that opens and closes the load, which will be described later, 7 is an instrument current transformer that measures the output current of the generator 5, and 8 is an instrument current transformer that measures each in-station load current. 9 is an instrument transformer for measuring the bus voltage; 10 is a load cutoff signal that cuts off the in-station load breaker 6; 11 is an automatic load selection cutoff control unit that executes a predetermined calculation and outputs the load cutoff signal 10; It is.

Next, the operation will be explained. First, it is assumed that the in-house load (L) is supplied with power by purchasing power from an electric power company and by a generator 5 using private power generation equipment.

Here, if a failure occurs in the generator 5, the generator breaker 4 will immediately trip. At this time, the automatic load selection/cutoff control unit 11 instantly connects the instrument current transformer 7 and the bus instrument transformer 9 to the generator so that the power receiving secondary shield switch 3 does not trip due to overload. The generator output at the time of disconnection of 5 is detected. Then, the automatic load selection/cutoff control unit 11 selects the station load (L) corresponding to the generator output at the time of disconnection from the instrument current transformer 8 and the instrument transformer 9 of the load feeder, and outputs the load cutoff signal 10. is output to trip the corresponding local load breaker 6. In this case, the load cutoff power (AP) to be cut off had the same capacity as the output (cp) of the private power generation equipment and was subject to parallel disconnection. In addition,
Japanese Utility Model Publication No. 63-30196 is similar to the above-mentioned conventional automatic load selection cutoff device.

[Problem to be solved by the invention]

Conventional automatic load selection cutoff devices are configured as described above, so even if there is a considerable difference between the contracted power and the received power, and there is a surplus in the received power capacity, the private power generation equipment output ( It cuts off load cutting power (AP) of the same capacity as GP). Therefore, originally, there was no need to cut off the load for the margin when the generator was disconnected, and there was a problem such as wanting to minimize the amount of load shedding when the generator was disconnected in order to increase the factory operating rate.

This invention was made in order to solve the above-mentioned problems, and it is an automatic load selection and disconnection system that enables high-efficiency operation by minimizing the load to be disconnected when a generator is disconnected. The purpose is to obtain equipment.

[Means to solve the problem]

The automatic load selection cutoff device according to the present invention includes a received power measuring means for measuring the received power of 70 purchased power when the power purchased by the electric power company and the output of the private power generation equipment are operated in parallel, and the received power measuring means is connected to, calculates the power receiving margin from the received power and the contract power, and when the generator breaker trips, subtracts the power receiving margin from the output of the private power generation equipment immediately before the trip to obtain the load cutoff power, The present invention includes an automatic load selection and disconnection control section that generates a load disconnection signal.

[For production]

The automatic load cutoff control unit in this invention calculates the difference between the contracted power and the received power from the private power generation equipment output, that is,
A load cutoff signal is output so as to cut off the station load corresponding to the power obtained by subtracting the received power margin. This operation minimizes the factory load that is cut off and increases the factory operating efficiency.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same parts as in FIG. 2 are designated by the same reference numerals. In FIG. . Here, the power receiving meter current transformer 12 and the power receiving meter transformer 13 are collectively referred to as received power measuring means.

Next, the operation will be explained. First, it is assumed that power is supplied to the station load (L) by the power receiving unit and the generator 5 as in the conventional example. Here, if the generator 5 fails for some reason and the generator breaker 4 trips, the automatic load selection and disconnection control section 11 instantly switches the instrument current transformer 7 and the bus instrument transformer 9. Private power generation equipment output (c
p) is detected and taken in. At the same time, the following calculation is executed from the power receiving meter current transformer 12 and the power receiving meter transformer 13.

Load cutting power (AP) - Private power generation equipment output (GP)
-AP where, △P = CP - DP △P; Received surplus power CP: Contract power DP; Received power, that is, the received power (DP) is detected and taken in, and the difference (AP) from the contract power (cp) is calculated. The private power generation equipment output (
GP) and the corresponding internal load (L)
is selected and the load breaker 6 is controlled to trip using the load breaker signal 10.

In the above embodiment, the operation of the on-site load breaker when the private power generation equipment is disconnected is explained, but even when the power receiving side is disconnected, the control is such that the on-site load is cut off by subtracting the margin of the output of the private generator equipment. The same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, when the generator is disconnected, the automatic load selection and disconnection control unit disconnects the in-house load corresponding to the electric power obtained by subtracting the difference between the contracted power and the received power from the private power generation equipment output. As a result, efficient load shedding can be carried out, which has the effect of improving factory operating efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an automatic load selection and cutoff device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional automatic load selection and cutoff device. In the figure, 10 is a load cutoff signal, 11 is an automatic load selection cutoff control section, 12 is a current transformer for a power receiving meter, and 13 is a transformer for a power receiving meter. In addition, the same symbols in the figures indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation 10:'! <'aLwH Ike 12゛+Electrical meter grade: 9th grade 13, Barley pressure gauge for power receiving meter

Claims (1)

[Claims] In an automatic load selection breaker that selectively cuts off a load when a generator breaker trips during parallel operation of power purchased by a power company and the output of a private power generation facility, a received power measuring means for measuring the received power of the purchased power; , connected to the received power measuring means, calculates the received surplus power from the received power and contract power, and when the generator breaker trips, subtracts the received surplus power from the output of the private power generating equipment immediately before the trip. 1. An automatic load selection and cutoff device comprising: an automatic load selection and cutoff control unit that determines load cutoff power and generates a load cutoff signal.