Field Circuit Coupling Simulation Of Multi-stage Magnetic Valve MCR Based On Equivalent Magnetization Characteristics

Magnetic controlled reactor(MCR)is widely used in power grid for reactive power compensation and overvoltage suppression as a reactor with adjustable capacity and high reliability.However,there are still two problems in the actual operation of ordinary MCR: one is that the inertia of ordinary MCR is great,it usually needs more than ten power frequency when outputs its rated current from zero;the is low regulation efficiency of ordinary MCR,which can not realize the automatic regulation of capacity fluctuation.With the rapid development of modern industry,the requirement of power quality of power grid is higher and higher.The problems of slow response and low regulation efficiency of MCR need to be solved.Single-phase four column MCR is taken as the research object in this paper.The harmonic characteristics of multi-stage MCR are analyzed.The optimal stage of magnetic valve is determined to be four.According to the scale difference of the core valve,the mesh of the valve segment is intensive,which leads to the problem of large calculation and difficult convergence of the simulation results.Based on the concept of equivalent magnetic field strength,the equivalent method of magnetization characteristic curve of MCR magnetic valve is proposed.To solve the problem of slow response of MCR,a method of increasing DC control voltage and permeability is proposed to improve the response process of MCR,and the automatic regulation of output capacity of MCR is realized to improve the regulation efficiency.Firstly,the equivalent of magnetic valve is achieved and the mathematical model of the equivalent magnetization characteristic is derived.With the help of magnet software,the model before and after the equivalence are built.It can be seen from the analysis of mesh generation results that with the increase of stages,the mesh generation density of the magnetic valve segment increases gradually,while the mesh generation results of the magnetic valve segment of the model after the equivalence are consistent.It shows that the higher the number of MCR magnetic valve is,the shorter the simulation time is.Through the finite element comparative simulation experiment,the simulation time before and after equivalent MCR is reduced by 28.96%,39.59%,64.48% and 72.3% respectively.Then,based on the analysis method of magnet simulation,the analysis method of magnet and Simulink joint simulation is introduced.By comparing and analyzing the current flowing through the inductor and the voltage at both ends of the inductor under the joint simulation of RLC circuit and Simulink simulation,the correctness of the joint simulation method is verified.The change of magnetic induction intensity of MCR in a power frequency period is analyzed,which is consistent with the theoretical analysis results.Finally,the fast response joint simulation platform and automatic control joint simulation platform are built.The simulation results show that the response time of multistage MCR is in a power frequency cycle in the process of excitation and demagnetization under the external high DC control voltage;in the automatic control environment,the error is less than 2% in the process of multi-stage MCR excitation and capacity fluctuation.