Generator terminal potential transformer inter-turn short circuit on-line identification method

Abstract

The invention discloses a generator terminal potential transformer inter-turn short circuit on-line identification method. The generator terminal potential transformer inter-turn short circuit on-line identification method includes the following steps that: main transformer high-voltage side zero sequence voltage, factory transformer low-voltage side zero sequence voltage and generator neutral point zero sequence voltage are measured, fundamental wave effective values of the main transformer high-voltage side zero sequence voltage, factory transformer low-voltage side zero sequence voltage and generator neutral point zero sequence voltage are calculated respectively; the value of insulation resistance against ground of a stator winding is calculated through utilizing an injection type stator grounding protection principle; and when the fundamental wave effective value of the generator neutral point zero sequence voltage is larger than a stator grounding protection action constant value, and the fundamental wave effective values of the main transformer high-voltage side zero sequence voltage and the factory transformer low-voltage side zero sequence voltage are both lower than the constant value, and the value of the insulation resistance against ground of the stator winding is not decreased, it judges that a generator terminal potential transformer inter-turn short circuit occurs, and warning is performed after time delay, and a fundamental wave zero sequence voltage stator grounding protection sensitive section is blocked. The generator terminal potential transformer inter-turn short circuit on-line identification method of the invention can accurately judge generator terminal potential transformer (PT) inter-turn short circuit faults, and therefore, misoperation of stator grounding protection when the short circuits occur can be effectively prevented, and troubleshooting time can be greatly reduced.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to an on-line discrimination method for inter-turn short circuit of a generator terminal voltage transformer (PT) and a corresponding relay protection device or monitoring device. Background technique [0002] When the PT turn-to-turn short-circuit fault at the generator terminal will cause the zero-sequence voltage of the generator stator winding to the ground to rise, it will cause the stator grounding protection action of the fundamental wave zero-sequence voltage type generator. Since it is impossible to distinguish between PT turn-to-turn short circuit and stator single-phase ground fault, the workload of troubleshooting is also increased. In view of the above reasons, it is necessary to study an online identification method for PT inter-turn short circuit at the generator end, which can effectively prevent the misoperation of the stator gro...

AI Technical Summary

Problems solved by technology

[0002] When the PT turn-to-turn short circuit fault occurs at the generator terminal, the zero-sequence voltage of the generator stator winding to the ground will increase, resulting in the action of the fundamental zero-sequence voltage type generator stator grounding protection

Since it is impossible to distinguish between PT turn-to-turn short circuit and stator single-phase ground fault, it also increases the workload of troubleshooting

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