A Fault Detection Method for Stator Winding Asymmetry of Doubly-fed Wind Turbine Generator

Abstract

The invention discloses a double-feed wind power generator stator winding asymmetric fault detection method. The method comprises respectively obtaining a rotor side current signal and a rotor side voltage signal through a current sensor and a voltage sensor at the rotor side of a double-feed wind power generator; if it is determined that a sampling time is reached, converting an acquired voltage signal from a line voltage into a phase voltage; multiplying the current signal and the voltage signal of each phase to obtain a power signal of each phase; performing corresponding addition on the power signal of each phase to obtain a total three-phase power signal; performing Fourier transformation on the total three-phase power signal to obtain a rotor side power frequency spectrum graph; extracting the amplitude at 2f1 in the frequency spectrum graph as a characteristic value, f1 being a stator side electrical network fundamental frequency; and determining whether the characteristic value at a motor fault state is greater than the characteristic value at a motor faultless state by 1.2 to 1.6 times, and if so, emitting a fault alarm. By using the method provided by the invention, sensitive real-time online fault detection can be realized, the anti-interference capability is quite high, and the realization is simple.

Description

technical field [0001] The invention relates to a fault detection method of a doubly-fed wind power generator, in particular to a detection method for an asymmetry fault of a stator winding of a doubly-fed wind power generator. Background technique [0002] With the increasing installed capacity of grid-connected wind turbines in my country and the development of offshore wind power generation, improving and ensuring the reliability of wind turbine operation has become the focus of attention both at home and abroad. Doubly-fed wind turbine is currently a mainstream model used in wind turbines. Wind turbines usually work in harsh environments and under all-weather alternating load conditions, and the probability of failure is relatively high. Among them, double-fed A large part of the faults in wind turbines are caused by the stator. Therefore, online detection of stator winding faults of doubly-fed wind turbines is extremely important. [0003] At present, the generator wi...

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Problems solved by technology

[0003] At present, the generator winding fault is monitored by monitoring the radial vibration characteristics of the generator, but this method requires an external vibration sensor, which has technical difficulties for the wind turbine in operation, and also increases the operating cost of the wind turbine

There is also an online detection of DFIG stator winding faults by extracting feature quantities from the rotor-side current spectrum or voltage spectrum. However, since the slip s is included in the eigenfrequency expression, for example, the eigenfrequency of the current spectrum is f r =(2k±s)f 1 , f 1 It is the fundamental frequency of the stator side power grid, where k is a positive integer, and the tracking and calculation accuracy of the slip s is very demanding, the calculation amount is large, and errors are prone to occur

In addition, axial magnetic flux, stator negative sequence current, wavelet analysis and other methods are used to detect stator winding faults, but their sensitivity and reliability have yet to be verified.

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