Dual-periodic adjustable variable-polarity square-wave voltage type rotor ground protection method

Abstract

The invention discloses a dual-periodic adjustable variable-polarity square-wave voltage type rotor ground protection method, belonging to the technical field of generator rotor ground protection. The method is characterized by adjustable square-wave voltage polarity transformation period and adjustable window period calculated by direct current component sampling. Through detecting the charge-discharge time of a generator rotor winding ground capacitor, the polarity transformation period of the injection type square-wave voltage can be adjusted, thereby avoiding the interference caused by the charge-discharge transient state of the ground capacitor. Through detecting the period of low frequency component vibration caused by generator rotor eccentricity or magnetic pole asymmetry, the window period calculated by direct current component sampling can be adjusted, thus avoiding the interference from low frequency component caused by rotor eccentricity and magnetic poles asymmetry.

Description

[0001] technical field [0002] The patent of the invention relates to a new principle for judging the grounding protection of the generator rotor by a double-cycle adjustable square wave voltage method of variable polarity, which belongs to the technical field of the grounding protection of the generator rotor. Background technique [0003] At present, the rotor grounding protection of reaction generators commonly used in the industry mainly includes two categories: injection type and non-injection type. [0004] The non-injection rotor grounding protection includes the ping-pong conversion rotor grounding protection and the bridge rotor grounding protection, but the biggest disadvantage of the non-injection protection is that it can only work when the generator is running normally and the rotor is applied with the excitation voltage, and in the This kind of protection cannot play a protective role in the process of starting and stopping the generator and when the generator...

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Problems solved by technology

[0007] In order to solve the problem of misoperation of the rotor one-point grounding protection caused by the different sizes of the distributed capacitance of the generator rotor winding to the ground, and also to solve the problem of low-frequency interference components generated in the sampled DC voltage due to the eccentricity of the rotor of the generator set and the incomplete symmetry of the magnetic poles. In order to solve the problem of refusal or misoperation of one-point grounding protection of the rotor, the present invention provides a double-period adjustable polarity-changing square wave voltage rotor grounding protection method. The double-period adjustable means that the square wave polarity change period can be adjusted and the Component sampling calculation window cycle can be adjusted

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