Bus current transformer disconnection identifying method and device, and differential protection method and device

Abstract

The invention relates to a bus current transformer disconnection identifying method and device, and a differential protection method and device. The bus current transformer disconnection identifying method comprises the following steps: determining whether the current transformer disconnection start judgment is satisfied; and if the current transformer disconnection start judgment is satisfied, determining whether the following disconnection judgment conditions are satisfied: (a) the disconnection branch of the current transformer has a zero-sequence current, and the current of any phase is suddenly changed and the current is reduced; (b) before the current transformer disconnection start, the three-phase currents of the branch have currents and have no zero-sequence current; and after thecurrent transformer disconnection start, the currents of other phases of the branch are unchanged; (C) when the current transformer disconnection start, other branches have no zero-sequence current,and the phase currents are not changed; and (d) when the current transformer disconnection start, the bus of the side has no zero-sequence voltage and negative-sequence voltage, and the zero-sequencevoltage is not changed; and determining that the current transformer is disconnected if all the conditions in the disconnection judgment conditions are satisfied. The invention can quickly and accurately judge whether the current transformer is disconnected or not, and avoid misoperation of the bus differential protection.

Description

technical field [0001] The invention relates to a disconnection identification method of a bus current transformer, a differential protection method and a device, and belongs to the technical field of electric power system relay protection. Background technique [0002] "Electrical Industry Safety Work Regulations" stipulates that it is strictly forbidden to open the circuit when the secondary circuit of the live current transformer is working. The secondary winding of the current transformer used for high-voltage busbar protection has many turns, and the open circuit voltage is very high. burnt, and even threaten personal safety. Therefore, the current regulations and countermeasures require that the differential protection be blocked when the busbar protection current transformer is disconnected, but the time for the disconnection of the busbar protection current transformer is usually longer, and the load current of the disconnection branch may cause the busbar different...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a busbar current transformer disconnection identification method and device, which are used to solve the problem of long time for busbar differential protection current transformer disconnection identification; the present invention also provides a busbar differential protection method and The device is used to solve the problem of misoperation of the bus differential protection after the bus protection current transformer is disconnected

[0005] In order to solve the problem of long time for discriminating the disconnection of the current transformer of the bus differential protection, the present invention provides a method for identifying the disconnection of the current transformer of the bus, the steps are as follows:

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