A method for switching secondary current loops in bypass transformer switching operation CT

Abstract

The invention provides a method for switching secondary current loops of CTs operated by bypass switches instead of transformers. is the target object; the main transformer protection device exits the protection state; short-circuit and ground the differential protection function connecting piece in the target object, and disconnect the connection between the target object and the main transformer protection device; remove the four differential protection devices in the switching object Short-circuit between the functional connecting pieces and connect with the main transformer protection device, and further detect the abnormality of the connection; after the detection is normal, put the main transformer protection device into the protection state, so that the switching object and the main transformer protection device are connected to realize The switching object changes from open circuit to conduction, and the target object changes from conduction to open circuit. The implementation of the invention can overcome the existing problems before and after switching of the existing CT secondary current loop, and discover hidden dangers in time.

Description

technical field [0001] The invention relates to the technical field of relay protection, in particular to a method for switching secondary current circuits of CTs operated by bypass transformer switches. Background technique [0002] In some substation constructions there are complete side bays, the main function is to replace them with complete side bays when a certain bay of the substation needs to be overhauled under the premise of no power outage and no impact on user power supply. At present, the bypass line interval is replaced by a complete set (including protection, switch, operation circuit, CT circuit, etc.), while the bypass can only replace the switch when replacing the transformer interval, and cannot replace the protection, that is, when the transformer switch needs to be overhauled, the load The required main transformer cannot be shut down. [0003] Such as figure 1 As shown in FIG. 2 , it is a schematic diagram of the connection of the main transformer of ...

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Problems solved by technology

[0004] However, no matter how it is prevented, many problems often occur during the operation process: (1) The differential protection function connection piece is not temporarily withdrawn before the CT secondary current circuit is switched, resulting in protection malfunction (due to careless operation during the operation process) There is a deviation, which will cause a differential current and cause a malfunction of the protection); (2) During the switching process of the CT secondary current circuit, measures to prevent CT open circuit are not done, resulting in CT secondary open circuit and electric injury to the staff; (3) Carrying out After the switching of the CT secondary current circuit is completed, the protection is not checked for abnormalities, and the differential protection function connection piece is blindly put in, resulting in protection malfunction (due to the deviation in the operation process, the differential current causes the protection malfunction to fail to reset); (4) In the whole work of switching the CT secondary current loop, it is not guaranteed that the loop is only grounded at one point

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