Double-feed wind power generator stator short circuit current calculating method under the condition of asymmetric faults

Abstract

The invention discloses a double-feed wind power generator stator short circuit current calculating method under the condition of asymmetric faults. The method comprises the following steps: establishing a voltage equation and a flux linkage equation of a double-feed wind power generator, in the form of space vectors under a stator shaft system; establishing stator and rotor current expressions, and establishing a stator positive sequence flux linkage expression after the faults; establishing a rotor positive sequence flux linkage expression after the faults; establishing a stator positive sequence current expression of the double-feed wind power generator under the condition of an asymmetric fall of voltage at a machine end; establishing a stator negative sequence flux linkage expression after the asymmetric fall of the voltage at the machine end; establishing a rotor negative sequence flux linkage expression after the asymmetric fall of the voltage at the machine end; establishing a stator negative sequence current expression after the asymmetric fall of the voltage at the machine end; and finally obtaining a stator current expression after the asymmetric fall of the voltage at the machine end. According to the invention, the problems of affected relay protection and control accessed to a wind power field, affected safe and stable operation of a wind power generator set and the like, caused by lack of research on a simple and effective stator short-circuit current calculation method under the condition of the asymmetric faults in the prior art are solved.

Description

technical field [0001] The invention belongs to the technical field of wind power generation in electric power systems, and in particular relates to a calculation method for stator short-circuit current of a doubly-fed wind power generator under an asymmetrical fault. Background technique [0002] Doubly-fed wind turbines are widely used in wind power generation systems due to their advantages such as small converter capacity and the ability to achieve power decoupling control. When the power grid fails, the terminal voltage of the double-fed wind turbine will drop. Due to the coupling of the stator and rotor flux linkage, the rotor winding may generate overcurrent, which will damage the converter and threaten the safe operation of the wind turbine. For this reason, the most commonly used method at present is to put in a crowbar circuit, bypass the rotor-side converter, block the rotor-side converter at the same time, and use the crowbar resistance to limit the rotor current...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a simple and effective method for calculating the stator short-circuit current of a doubly-fed wind power generator under an asymmetric fault. The calculation process does not need to solve differential equations to solve the lack of simple and effective asymmetry in the prior art Research on the calculation method of stator short-circuit current under fault conditions, resulting in problems affecting the relay protection and control of wind farm connection and the safe and stable operation of wind turbines

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