| Accurate calculation of transient electric field distribution of high voltage electrical equipment is one of the most important steps in equipment manufacturing and optimization design.According to the dielectric relaxation phenomenon,the dielectric constant of a medium is related to the frequency of its voltage,so it is necessary to consider the dielectric relaxation process of a medium when calculating the transient electric field.In addition,at present,the simulation software market is monopolized by AN SYS and other foreign companies.Due to the important role of simulation software in engineering applications,the localization of simulation software needs to be further developed.This paper focuses on the domestic demand of electric field simulation software,aiming at the transient electric field calculation function including dielectric relaxation process,and gradually carries out research from three aspects:finite element calculation method in complex frequency domain,storage and solution method of large sparse complex matrix equation,and application of simulation software.The first commercial simulation software which can accurately calculate the transient electric field even considering the dielectric relaxation process of the medium is developed.In this paper,electric field calculation method is studied and software is applied to achieve more accurate and convenient transient electric field calculation of electrical equipment.Firstly,the initial value-boundary value problem considering the dielectric relaxation process is given,the finite element equation in the transient complex frequency domain considering the relaxation process is derived,and the solving process of the finite element equation in the transient complex frequency domain is analyzed.This paper analyzes the functional requirements of the software,designs the technical scheme to softwareize the calculation method,and makes it clear that the storage and calculation method of large sparse matrix is the key link in the development of commercial electromagnetic simulation software.Secondly,we write a C++program for complex sparse matrix storage based on the cross list method,define the complex number class and the member functions of its basic operations,realize the complex number of sparse matrix,and verify the storage efficiency.The program of operation between complex sparse matrix is written and the basic operation process of complex sparse matrix is realized.On this basis,combining the incomplete Cholesky preprocessing technique with the CBCG method,an IC-CBCG method and its C++program suitable for cross-list storage were proposed and written.Finally,the simulation software interface of relaxation electric field calculation module based on domestic Simdroid software is presented,and the whole process from simulation model drawing,boundary condition setting to simulation results viewing is introduced in detail.The transient electric field distribution of the two-layer dielectric parallel plate model at step voltage is simulated by using the software,and the effect of dielectric relaxation process on the electric field distribution characteristics is analysed.The electric field distribution of 4.5kV elastic crimped IGBT device is simulated by the software under two actual voltages.The electric field characteristics of the device under different working conditions are analyzed and compared in detail.The distribution position of the maximum electric field and the variation rule of the maximum electric field mode value are expounded.The regulation method of electric field is proposed. |
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