The method to solve the fault of hysteresis cut-off of generator stator grounding protection

Abstract

The invention relates to a method for solving generator stator ground protection lag removal faults. The method comprises the following three measures: (1) using a one-time voltage applying method to detect the accuracy of secondary voltage sampling value and ensure that collection-protecting neutral point voltage is at a certain value when grounding failures occur on a wire outlet side of a generator; (2) setting fundamental wave zero sequence voltage stator ground protection into two sections, wherein a non-sensitive section sends out signals, and a sensitive section trips; (3) changing the action trip time of generator fundamental wave zero sequence voltage stator ground protection from 1.5s to 0.2s. The three measures play roles jointly. The method effectively solves the problem of generator stator grounding protection lag removal faults. Operation results show that after the measures are taken, original characteristics of generator stator ground protection are not influenced, and the problem of stator ground protection lag removal faults is thoroughly solved. Consequently, the problem that stator ground protection time delay overlong motion causes a unit to be damaged more severely is avoided, and the method plays an important role in ensuring normal operation of a power grid.

Description

technical field [0001] The invention relates to the protection technology of a power system substation, in particular to a method for solving the hysteresis cut-off fault of the generator stator grounding protection. Background technique [0002] At present, there have been a number of generator stator grounding in Yantai Power Plant, Liaocheng Power Plant, Weifang Power Plant, etc., and the protection lagged to remove the fault, which led to major accidents such as inter-turn short circuit and interphase short circuit. [0003] For example, in 2007, a stator ground fault occurred in phase C of #4 generator in Weifang Power Plant, which developed into a turn-to-turn short circuit fault, which caused the lead wire of phase C of the stator of the generator to be blown, and the insulation of B and C relative to the ground was 0MΩ. The action time between turns of the generator stator is 0.2s, and the setting time of the stator grounding protection is 1.5s. In the end, the turn...

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Problems solved by technology

[0006] The purpose of the present invention is to solve the above problems and provide a method for solving the hysteresis cut-off fault of the stator grounding protection of the generator, which can effectively solve the problem of the hysteresis cut-off fault of the protection when the stator ground fault occurs in the generator, so as to reduce the damage of the generator At the same time, setting a delay of 0.2s can avoid the influence of the transient process and will not cause malfunction, thus effectively avoiding a series of problems such as protection malfunction, switch error trip, signal error sending, and unit error stop. Thus avoiding the impact of equipment accident expansion on the power grid

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