Bus differential protection polarity test method

Abstract

The present invention provides a bus differential protection polarity test method. The technical key point of the method is as follows: a current transformer of a random tested branch line on the I segment bus of a transformer substation is used as a reference point, a large current which flows into a tested branch line on the II segment of the transformer substation through a bus coupling currenttransformer is exerted from a primary non-polar end of the branch current transformer; and then the bus differential protection polarities of other branch lines of the transformer substations are sequentially checked while the connection modes of the tested branch line I and the bus coupling branch line are kept unchanged. The method of the invention can check out the miswiring or error wiring ofthe secondary connection of each branch line current transformer with a same voltage level in the transformer substation for preventing the error wiring of the bus differential protection polarity ofthe newly-built transformer substation. The protection checking time when the newly-built transformer substation is put into operation is reduced, and each user is supplied with electricity safely and quickly. The reliability of bus differential protection operation in the transformer is increased, and the stable operation of the electrical power system is guaranteed.

Description

technical field [0001] The invention relates to a method for testing the polarity of differential protection of a substation bus in a power system, belonging to the field of power system relay protection and safety automatic device inspection. Background technique [0002] The substation is the power supply hub of the power system. It supplies power to users through the branch circuit breakers on the busbar in the substation. Busbar differential protection is a relay protection device that protects the busbars of substations. The busbar differential protection is to connect all the current transformers connected to the branch circuits on the busbar to the differential circuit according to the same name and phase and the same polarity. Its main function is to quickly disconnect the faulty busbar when the protected busbar fails. For all branch circuit breakers, the busbar differential protection device refuses to act if a fault occurs outside the busbar range. Since the busb...

AI Technical Summary

Problems solved by technology

This method has the following defects in the following three aspects: 1) When withdrawing from the bus differential protection for on-load measurement, due to the large number of branches on the bus, the calibration time is long. If the bus fails during this period, the bus differential The dynamic protection refuses to act, causing vicious power grid accidents

2) The polarity verification of busbar differential protection is greatly affected by the load current, and polarity verification errors may occur when the load current is small

3) According to the measurement results, when it is found that the polarity of the current transformer of a certain branch of the bus differential protection is incorrectly connected, it is difficult to rectify the polarity of the current transformer of this branch because all the branches are live.

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