Electromagnetic Field And Temperature Field Of Permanent Magnet Wind Generator With Stator Winding Open Circuit Fault

In the background of energy shortage,environmental pollution and climate change increasingly prominent,wind power has been developing vigorously,especially the permanent magnet direct-drive or half direct-drive wind generators is growing rapidly.With the increasing installed capacity and grid capacity of wind generator,the proportion of wind power generators is increasing.A fault of large-capacity wind generator in the course of its operation not only results in the machine itself damaged,but may even results in an inestimable loss of grid,so more and more attention is paid to the research of wind generator faults.Wind generator towards the trend of large-capacity development,in large-capacity wind generators,each phase winding generally consists of a number of parallel branches winding,subject to thermal,electrical,mechanical,environmental stress and other factors,the stator windings may open branch or single-phase open circuit fault.In this thesis,the stator winding open circuit fault has been studied.A 1.5MW,4 parallel-branch permanent magnet wind generator is main fault object in the thesis.Firstly,the global 2-D transient coupled field-circuit coupling model was established,comparing the electromagnetic field calculation results of rated conditions which calculated by the finite element method with the designed values,verified the correctness of the model establishment.On this basis,a variety of stator winding open circuit fault models were established.Then,the change law of tooth magnetic flux density and air-gap flux density of stator winding under single phase open circuit fault was analyzed.And the harmonic spectrums of the air-gap flux density in different stator winding branches open circuit fault,the influences of the stator winding fault on the electromagnetic force distribution and the electromagnetic torque were analyzed.Furthermore,the branch currents of three phases of the stator winding under the fault of branch open circuit were calculated.Meanwhile,the vales of stator winding parallel branches circulating current were calculated by taking single branch and in-phase adjacent branch open circuit fault as an example.Secondly,the negative sequence current was calculated with stator winding open circuit faults using the symmetrical component method.And the influence of the degree,position,wind speed on the negative sequence current that effect on eddy current loss of permanent magnet was studied.At the same time,the negative sequence transient electromagnetic field model of generator stator winding with different open circuit faults was established.Based on this,the effect of negative sequence current on the eddy current loss of the permanent magnet under stator winding faults were studied.Finally,the global 3-D steady-state temperature field calculation model was established.By the finite model,the temperature field with the stator winding of single branch,in-phase adjacent branch,single-phase open circuit fault were solved.Through the compared with temperature distribution,the influent of copper loss,iron loss,permanent magnet eddy current loss with different stator winding open circuit faults on the temperature distribution was researched.