Study On Electromagnetic Design And Fault Simulation Of Megawatt Hts Wind Generator

As fossil energy shortage and environmental pollution becoming more and more serious,offshore wind energy resource,which is a kind of abundant and renewable clean energy,is becoming more and more important.In order to reduce the generating cost,a large-capacity wind generator will be the trend for future development.However,the increase of output power per generator leads to the rapid growth of the volume and weight of traditional wind generators,which restricts the further development.As a promising way to solve this problem,high temperature superconductor(HTS)wind generator has the advantages of small volume,light weight and high power density.In this paper,we focus on a 2.5 MW HTS wind generator,and have completed the electromagnetic design and fault simulation.Firstly,according to the design parameters of each part,we have built a model for the HTS wind generator in the finite element simulation software of motor,JMAG,and have got the performance of the generator to verify the rationality of the design.Then,the field coils are make from the second generation HTS tapes,and its rated working current is set according to the critical current.We have studied a fast algorithm for evaluating the critical current of large-scale HTS coil.Calculated by a combination of stationary model in finite element simulation software Comsol and mathematical software Matlab,the critical current of a superconducting coil is 960 A,and the rated working current is set to 706 A by reserving a safety margin of 20% ~ 30%.And then,based on the special structure of the HTS wind generator,we have studied the performance affected by different materials in stator teeth.The results show that the ferromagnetic stator teeth improve the performance significantly,while the defects are also obvious.So when optimizing the material in stator teeth,the corresponding actions must be taken to weaken the possible adverse effects.Finally,we have studied the performance of the generator under short circuit conditions by simulation.In order to obtain more accurate results,the variation of rotational speed is considered,and the mechanical equation is set up according to the condition of constant input power.Because of the characteristics of the HTS wind generator,we found that the fault currents and the fault torque are heavier,which will damage the generator.In this paper,some methods to solve these problems are presented.The results will provide basis for the design of protection systems and support structures for the generator.