Offshore doubly fed motor stator winding turn-to-turn short circuit early fault identification method

Abstract

The invention relates to an offshore doubly fed motor stator winding turn-to-turn short circuit early fault identification method, and is used for judging the doubly fed motor stator winding turn-to-turn short circuit and determining the phase of the turn-to-turn short circuit. The method comprises the following steps that 1) the three-phase signals of an offshore doubly fed motor under fault identification are acquired, including the stator three-phase voltage, the rotor three-phase voltage, the stator three-phase current, the rotor three-phase current and the rotor rotating speed; 2) the three-phase signals are converted to a dq axis coordinate system, the motor parameters are acquired, then the three-phase signals are converted to an alphabeta axis coordinate system, the estimated stator current is acquired through an observer, and the estimated current difference is calculated and decomposed so that a fault severity factor xi is obtained; and 3) when the amplitude of the fault severity factor xi caused by the turn-to-turn short circuit fault reaches the fault early warning value, the stator winding turn-to-turn short circuit fault occurs on the offshore doubly fed motor under fault identification. Compared with the methods in the prior art, the offshore doubly fed motor stator winding turn-to-turn short circuit early fault identification method has the advantages that the fault phase can be reliably located and the robustness is high.

Description

technical field [0001] The invention relates to the field of fault identification of wind turbines, in particular to an early fault identification method for inter-turn short circuit of a stator winding of an offshore doubly-fed motor. Background technique [0002] With the rapid development of my country's wind power industry, the development of offshore wind power has become a new trend in the development of the wind power industry. During the period of the national "13th Five-Year Plan" energy plan, in order to promote the development of my country's deep-water, far-sea, and large-scale offshore wind farms, the National Energy Administration issued a "National Offshore Wind Power Development and Construction Plan (2014-2016)", 10.53 million kilowatts of offshore wind power projects have started construction, because the doubly-fed wind power generation system has many advantages such as low investment loss, high power generation efficiency, and convenient harmonic absorptio...

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Problems solved by technology

Cristian H.De et al published an article titled: Onlinemodel-based stator-fault detection and identification in induction motors in IEEE Transactions on Induction Motors, which proposed to diagnose induction motors by the difference between the stator current of the faulty motor and the observer current Inter-turn short circuit of the stator, but because the rotor side of the doubly-fed wind turbine needs the excitation of the frequency converter, so that it passes through the slip frequency energy, which is different from the working mode of the induction motor; and is affected by the excitation frequency converter on the rotor side, the derivation of fault characteristics is complex, so the diagnostic method proposed by it cannot be directly applied to doubly-fed wind turbines

Wei Shurong and others published an article in the Chinese Journal of Electrical Engineering entitled: Early Fault Identification of Stator Winding Inter-turn Short Circuit of Offshore Doubly-fed Motor Based on Pseudo-sequence Impedance. relationship, to obtain the inherent parameters (pseudo-sequence impedance) of double-fed motors, this method can be applied to double-fed motors. Slight inter-turn short-circuit fault of the stator, but this method cannot locate the faulty phase

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