Generator stator ground fault positioning method

Abstract

The invention discloses a generator stator ground fault positioning method. The method comprises the following steps: reading a generator terminal three-phase voltage vector from a fault recorder; calculating a zero-sequence voltage vector of the generator; determining a fault phase; calculating the advance angle of the zero-sequence voltage vector advance fault phase voltage vector of the generator; calculating a feature vector angle of the generator; when the advance angle is smaller than the feature vector angle, the ground fault occurs outside the generator; when the advance angle is equalto the feature vector angle, the ground fault occurs at the machine end; and when the advance angle is larger than the feature vector angle, the ground fault is located in the generator, and the ratio of the number of windings from the ground fault to the generator end to the number of windings from a generator neutral point can be calculated. The method has the advantages that the ground transition resistance does not need to be measured when the method is used for positioning the generator stator ground fault; according to the method, little fault information is needed for positioning the generator stator ground fault, the calculation process is simple, the calculation amount is small, and the method is easy to use on site.

Description

technical field [0001] The invention belongs to the technical field of relay protection of power plants, and in particular relates to a method for locating a ground fault of a generator stator. Background technique [0002] Generator stator single-phase ground fault is a relatively common fault in generators. If the stator grounding occurs inside the generator, it may further develop into a two-phase, three-phase grounding short circuit or inter-turn short circuit of the stator winding, causing serious damage to the generator. Therefore, according to DL / T684-2012 "Large Generator Transformer Relay "Guidelines for Calculation of Protection Setting", the single-phase grounding protection of the generator stator winding will operate to stop after a short delay of 0.3s ~ 1.0s. However, in practice, many stator single-phase grounding faults occur at the generator end and outside of the generator, such as dampness of the generator closed busbar, damage to the insulation of the PT...

AI Technical Summary

Problems solved by technology

If the stator grounding occurs inside the generator, it may further develop into a two-phase, three-phase grounding short circuit or inter-turn short circuit of the stator winding, causing serious damage to the generator. Therefore, according to DL / T684-2012 "Large Generator Transformer Relay Protection Setting Calculation Guidelines", the single-phase grounding protection of the generator stator winding acts on the shutdown after a short delay of 0.3s ~ 1.0s

However, in practice, many stator single-phase grounding faults occur at the generator end and outside of the generator, such as dampness of the generator closed busbar, damage to the insulation of the PT neutral point cable dedicated for generator turn-to-turn protection, damage to the supporting insulator of the generator closed busbar, etc.

[0003] The current generator stator grounding protection method still cannot distinguish whether the stator single-phase grounding fault occurs inside or outside the generator, whether it is 100% stator grounding protection composed of fundamental wave zero-sequence voltage and 3rd harmonic voltage, or injection stator Ground protection

When the generator stator grounding protection action is shut down, the power plant staff need to untie the connection between the generator and the outside, and check the insulation inside and outside of the generator separately, resulting in heavy workload and long downtime

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