A Calculation Method for Anti-interference of DC Flow in Rotor Grounding Protection

Abstract

The invention discloses a DC flow anti-interference algorithm for rotor grounding protection. In the invention, the DC voltage and leakage current of the rotor winding DC voltage and leakage current are pre-filtered and sampled, and N samples of DC voltage and sample leakage are first obtained before the switching of the electronic switch. Current, N accounts for 20% to 40% of the total sample S after low-pass filtering; then group the sample DC voltage and sample leakage current, calculate the average value of each group of samples, calculate the rate of change of the average value of the sample leakage current, and calculate the change rate According to the average value of the sample leakage current with the smallest rate of change and the average value of the DC voltage at the same time Value calculation of rotor grounding resistance and grounding position, effectively reducing the impact of fluctuations and interference on DC flow calculation; increasing the blocking judgment of severe fluctuations in DC voltage, effectively reducing the impact of severe fluctuations and interference on protection logic judgment.

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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