Rotor grounding protection direct current quantity anti-interference calculation method

Abstract

The invention discloses a rotor grounding protection direct current quantity anti-interference algorithm which is used for sampling direct current quantity pre-low-pass filtering such as direct-current voltage and leakage current of a rotor winding and comprises the following steps: firstly, acquiring N sample direct current voltage and sample leakage current before switching of an electronic switch, wherein N accounts for 20-40 percent of the total sample S after low-pass filtering; grouping the sample direct-current voltage and the sample leakage current, calculating the average value of each group of samples, calculating the change rate of the average value of the sample leakage current, sorting the change rates, selecting the average value of the sample leakage current with the minimumcorresponding change rate, and finding out the average value of the sample direct-current voltage at the same moment; and calculating the grounding resistance and the grounding position of the rotoraccording to the average value of the sample leakage current with the minimum change rate and the average value of the direct current voltage at the same moment, thereby effectively reducing the influence of fluctuation and interference on the calculation of the direct current quantity, adding dC voltage drastic fluctuation locking discrimination and effectively reducing the influence of drastic fluctuation and interference on protection logic discrimination.

Description

technical field [0001] The invention belongs to the technical field of electric power system relay protection, and relates to a calculation method for DC flow anti-interference of rotor grounding protection. Background technique [0002] A point ground fault in the generator rotor circuit is a common fault form of generator rotor winding insulation damage. When the rotor winding has a one-point ground fault, it will not cause harm to the generator; however, when the generator rotor winding has two-point ground faults at different positions, the large short-circuit current may burn the rotor body; The winding is short-circuited, which makes the air gap magnetic field uneven or distorted, which makes the electromagnetic torque uneven and causes the generator to vibrate and damage the generator. Therefore, the generator needs to be equipped with a reliable rotor grounding protection. At present, the injection type rotor ground protection and the ping-pong rotor ground protecti...

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Problems solved by technology

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for calculating the anti-interference of rotor grounding protection DC flow, so as to solve the problem of relatively large calculation errors of the rotor grounding resistance and grounding position in the prior art

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