System and method for verifying differential protection polarity of start-up and standby transformer branch

Abstract

The invention discloses a system and method for verifying differential protection polarity of a start-up and standby transformer branch. According to the invention, a generator is used as a current source, short-circuit tests are carried out on the high-voltage side and the low-voltage side of a start-up and standby transformer respectively, the polarity of a newly-accessed start-up and standby transformer branch for bus differential protection and the polarity of start-up and standby transformer differential protection are verified through short-circuit current, defects are eliminated, and normal operation of differential protection is guaranteed. The method solves the problem that the bus differential protection cannot be verified by load current of the start-up and standby transformer,a large amount of load does not need to be organized, it is unnecessary to rent dummy load, and the operability is high. The polarity of the bus differential protection and the polarity of the start-up and standby transformer differential protection are correct, and the misoperation of the differential protection is prevented.

Description

technical field [0001] The invention relates to the technical field of electric power testing, in particular to a system and method for verifying the polarity of differential protection of starting and standby substation branches. Background technique [0002] The differential protection is the main protection of the power system, and the operation of the differential protection is related to whether the fault can be correctly removed in the event of an accident. In the differential protection system, due to inaccurate wiring, inaccurate calibration, and multi-point grounding of the secondary circuit, protection misoperations occur from time to time. Therefore, polarity verification should be carried out before the differential protection is put into use. On the one hand, it is to eliminate defects such as wiring errors; on the other hand, it is to check whether the differential protection will malfunction when the equipment normally flows through the load current. The pola...

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Problems solved by technology

For the load calibration of the differential protection of the start-up substation branch, there are two difficulties: First, the load equipment of the power plant is mainly fans and water pumps. It is difficult to organize large loads in the early stage of construction, and it is necessary to rent dummy loads as loads. The cost is high; the second is that the start-up variable capacity is limited, usually 30MVA or 50MVA, and the high-voltage side load current is very small during normal operation, which is lower than the unbalanced current of the bus differential protection, and the pure load current cannot complete the calibration of the bus differential protection. test

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