On-line Discrimination Method for Turn-to-turn Short Circuit of Generator Terminal Voltage Transformer

Abstract

The invention discloses an on-line discrimination method for the inter-turn short circuit of a generator terminal voltage transformer, which measures the zero-sequence voltage on the high-voltage side of the main transformer, the zero-sequence voltage on the low-voltage side of the plant transformer, and the zero-sequence voltage on the neutral point of the generator, and calculates the respective The effective value of the fundamental wave of the zero-sequence voltage; the insulation resistance value of the stator winding to the ground is calculated by using the principle of injection-type stator grounding protection; The fundamental RMS value of the zero-sequence voltage on the high-voltage side of the main transformer and the RMS fundamental wave of the zero-sequence voltage on the low-voltage side of the factory transformer are both lower than the specified value, and the insulation resistance value of the stator winding to ground has not decreased, Then it is judged as inter-turn short circuit of voltage transformer at the generator terminal, alarm will be given after a delay, and the fundamental wave zero-sequence voltage stator grounding protection sensitive section will be blocked. The method of the invention can accurately judge the PT turn-to-turn short-circuit fault at the generator end, effectively prevent the stator grounding protection from malfunctioning in this case, and greatly shorten the troubleshooting time.

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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