Bus protection method for quick locking in CT (current transformer) asymmetric wire breakage

Abstract

The invention discloses a bus protection method for quick locking in CT (current transformer) asymmetric wire breakage. The bus protection method comprises the following steps of: calculating the electrical quantities of a differential current, a brake current, the sudden-change current of each branch, a zero-sequence current and the like; judging that the CT wire breakage occurs according to a criterion that the differential current increases while the brake current is unchanged, and starting differential protection if the CT wire breakage does not occur; selecting a suspected CT wire breakage branch according to whether a current exits in the branch of each circuit, and starting differential protection if the suspected CT wire breakage branch is not selected; and confirming the CT wire breakage according to information of the sudden-change currents and the zero-sequence currents of other branches except for the suspected CT wire breakage branch, and starting differential protection if the CT wire breakage cannot be determined. The protection method disclosed by the invention is capable of preventing the mistaken action of bus differential protection in case of CT asymmetric wire breakage and no high short-circuit current, and ensuring the correct action of bus differential protection regardless of whether the CT asymmetric wire breakage occurs in case of a high short-circuit current.

Description

technical field [0001] The invention relates to the field of power grid relay protection, in particular to a CT asymmetric disconnection fast blocking busbar protection algorithm. Background technique [0002] At present, most of the CT disconnections used for busbar protection are asymmetrical disconnections. The method for judging CT disconnection is that the bus differential current is greater than the CT disconnection locking value and after a certain delay. This method requires a delay of about 5s. If the time is too long, it may lead to asymmetric disconnection of the CT and misoperation of the bus differential protection. Contents of the invention [0003] The technical problem to be solved by the present invention is to provide a protection method for quickly blocking the busbar when CT asymmetrical disconnection occurs, which can prevent the misoperation of busbar differential protection when CT asymmetrical disconnection occurs and there is no large short-circuit...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a protection method for quickly blocking the busbar when CT asymmetrical disconnection occurs, which can prevent the misoperation of busbar differential protection when CT asymmetrical disconnection occurs and there is no large short-circuit current, and at the same time When a large short-circuit current occurs, it is impossible to ensure the correct operation of the bus differential protection whether there is a CT asymmetrical disconnection

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