Analysis Of The Electromagnetic And Temperature Fields Under Transient Process Of Three Phase Short Circuit In Permanent Magnet Wind Generator

Wind power brings human being new hope for overcoming the crisis of energyresources, which is one of the renewable energy resources with the fastestdevelopment and most mature condition of technology. The level of application andpopularity of the technology for off-grid wind energy generation, which is animportant portion of the utilization of wind power, expands the coverage ofelectricity, together with providing new factor for the way of power supply which isdifferent from grid. As follows are the analysis and research for the most commonshort-circuit fault of the Permanent-magnet Synchronous Motor used by off-gridpermanent-magnet wind energy generation system.Firstly, operating condition of the permanent-magnet generator in a off-grid windenergy generation system was analyzed, and a computing model of two-dimensionalelectromagnetic field was created according to the analysis theory of the permanent-magnet motor, at the same time, two methods for determining the position of eachphase of Fractional-slot Winding motor were analyzed, at last, the correspondenceproblem of stators and rotors of fractional slot double-layer lap winding permanentmagnet generator was resolved.With the application of Fourier decompositionprogram based on Least Squares, the distribution of electromagnetic field in motor asit running without load or running normally with load were computed after a analysisof radial Air-gap Field in motor, further, d-q axes synchronous impedance of withembedded rotor structure Permanet Magnet Synchronous Motor were analyzed withapplication of the Flux Linkage method; the changes of synchronous impedanceparameters of motor under different rotating speed and stator current were computed.At last, a experiment system was built for paving a way to the following faultanalysis. Secondly, two methods for analyzing fault current and solving parameters werecomputed and compared, building processes of d-q axes magnetic potential wereanalyzed to established transient reactance solving model and current expressionfitting equation of Prototype; d-q axes transient impedance, time constant and thecylic component and the acylic component in short-circuit current expression modelwere computed with a single motor as solving region; changes of d-q axes transientimpedance of with embedded rotor structure Permanet Magnet Synchronous Motorand the influence of stator current on were analyzed; changes of d-q axes transientparameter under different rotating speeds and every variable in short-current wereconsidered.Finally, taking the three-phase abrupt short circuit fault as a example, temperaturetransient processes of each structural part in permanent magnet motor under faultcondition were analyzed according to the basic principle of heat transfer; theinfluence of each component in current wave of three phase abrupt short-circuit faulton stator heat sources and the temperature transient processes of relative parts wereconsidered under low rotating speed; equivalent treatment methods of wastageproduced by each component of stator current under fault were analyzed and thecomputing result of prototype were validated by experiments.