Modeling Of VSC-HVDC Converter System And Analysis Of Conducting Electromagnetic Disturbance Characteristic

With the gradual improvement of the voltage and current level of IGBT,the key component of the flexible DC converter system,the switching time is gradually shortened and the energy loss in the operation is reduced.But higher switching speed is brought about by the voltage and current changes faster,the high-frequency signals along the converter valve,filter,transformer,reactor and other equipment for path propagation in a loop,the formation of broadband electromagnetic disturbance on secondary equipment.This will not only pose a hidden danger to the safe and stable operation of the commutation system,but also cause interference to the communication system,and may jeopardize the safety of the operator.Based on the combination of theory and experiment,a broadband circuit model is established for the key equipment of flexible DC converter system,which is related to the physical mechanism of components.Besides considering the low frequency characteristics,the influence of ground capacitance and mutual coupling parameters is also considered.With the help of network analyzer,a complete and systematic measurement of the impedance wide frequency characteristic of key equipment is carried out.Through the analysis and calculation of experimental data,the extraction method of broadband parameters of core devices in converter station is determined,and the validity of the model is verified by impedance characteristic simulation.In order to analyze the electromagnetic compatibility of flexible DC converter system,the measurement of conduction voltage is carried out with the help of the experimental platform of New Energy Laboratory of North China Electric Power University.In the time domain,the correctness of the flexible DC converter system constituted by the broadband model is verified,and the propagation and attenuation characteristics of the conducted electromagnetic disturbance are analyzed one by one.The broadband impedance model proposed in this paper can accurately describe the flexible DC converter the key device in the system,the model can be used to study the electromagnetic disturbance propagation and attenuation of the commutation system,provide a reference for the normal operation of the converter,converter valve and reactor equipment in china.