Research On Multiphysical Fields Of Power Capacitor And Its Series Reactor Under The Influence Of Harmonics

Power capacitors and their series reactors are important reactive compensation equipment and filtering devices in the power grid,which are widely used in various voltage levels of distribution networks.In recent years,with the increase of non-linear electrical equipment,the harmonic pollution in distribution network is becoming more and more serious,and the adverse consequences of harmonic on capacitor banks can not be ignored.Therefore,it is important to establish an accurate and effective simulation model of capacitors and reactors under harmonic interference and to study the damage mechanism of capacitors in multiphysical fields,which can provide reference for the insulation design,structure optimization and life prediction of capacitor banks,and it is of great significance to improve the operation of capacitor bank equipment in power system.Firstly,a metallized film capacitor with a rated capacity of 334 kvar and a rated voltage of 6.6 / 3 k V is taken as the research object.According to the winding structure characteristics of the capacitor elements,two-dimensional electric field simulation is carried out in the left side area through Maxwell 2D,and the influence of harmonics on the electric field of metallized film capacitor is explored.Furthermore,the dielectric loss and equivalent series resistance(ESR)loss of the capacitor under the influence of harmonics are analyzed,and the three-dimensional temperature field model of the capacitor is established.The influence of harmonics on the temperature rise of the capacitor is explored by constant voltage method and constant current method respectively.In order to improve the temperature rise of the capacitor,the temperature field simulation is carried out by changing the structure of the capacitor core,and the influence of adjusting the structure of the capacitor core on the maximum temperature of the capacitor is explored.Secondly,taking a three-phase core reactor with rated current of 88 A as the research object,the transient magnetic field of the core reactor is simulated by Maxwell 3D,and the influence of harmonics on the core magnetic field of the reactor is explored.On this basis,the winding loss and core loss of the reactor under the influence of harmonics are analyzed.Based on the principle of heat transfer and fluid mechanics,the magneto-thermal-fluid multiphysical fields coupling simulation of core reactor is carried out.The temperature distribution of core reactor is obtained in Fluent,and the influence of harmonic interference on the temperature rise characteristics of core reactor is explored.In order to solve the problem of long time and heavy workload in the simulation of the influence of harmonics on the reactor,a method of secondary development of ANSYS by VC++ based on APDL(ANSYS Parametric Design Language)is proposed to realize the automatic simulation and batch simulation functions of ANSYS.Finally,taking the series type of BKMJ0.4-30-3 metallized film capacitor and CKSG-1.8/0.4-6% core reactor as the research object,the voltage and current excitations are solved by superposition method and field-circuit coupling method.Combined with the simulation method of capacitor temperature field and the magneto-thermal-fluid coupling method of the reactor under harmonic condition,The simulation data of the temperature field of the capacitor bank under harmonic interference is obtained.The test platform of capacitor bank temperature rise under harmonic interference is built,and the test temperature data is compared with the simulation temperature data to verify the accuracy of the simulation model and the effectiveness of the simulation method.