Optimal Design Of Commutation Loop For Double Fracture DC Vacuum Circuit Breaker

In order to solve the problem of power system ecological environment caused by non-renewable fossil energy consumption,new energy generation,transmission,distribution,use and storage have become the research hotspots of domestic and foreign scholars.Multi-terminal HVDC is the key technology to improve the safety,reliability and stability of new energy generation and grid-connected.As one of the control and protection equipments in the multi-terminal HVDC transmission system,the HV voltage grade DC Vacuum circuit breaker has a direct influence on the whole life cycle stability of the multi-terminal DC system.In this paper,an active DC vacuum circuit breaker is studied to analyze and optimize the converter topology,the parameters of the converter loop and the commutation scheme of the single fracture and the double break DC vacuum circuit breaker,and a model of the DC vacuum circuit converter circuit based on system redundancy is proposed.Based on the analysis of secondary flutter structure of active DC vacuum circuit breaker,the parameters of commutation loop are determined to improve the breaking performance of DC vacuum circuit breaker.Using genetic algorithm,combined with the experimental platform system parameters,in order to optimize the performance and the lowest cost of the commutation loop,the influence of the frequency of commutation on the arc current and the transient recovery voltage of the single break DC vacuum circuit breaker is found.With 60 kV double breaks DC vacuum circuit breaker as the research object,in this paper,two kinds of commutation secondary flutter schemes are proposed,optimal circuit parameters are compared,the transient recovery voltage rise rate and the post arc current drop rate distribution of the double breaks DC vacuum circuit breaker under different topological schemes are analyzed,and the optimal circuit design scheme for the breaking performance of the double break DC vacuum breaker is determined.Based on the experimental platform of single fracture and double break DC vacuum circuit breaker,the simulation results are compared with the experimental analysis,and the model is amended.Through the Regulation model constraint condition and the system evaluation standard,multi-scale fusion analysis is carried out,with the open rate and low cost as the two-level optimization objective,the typical DC vacuum circuit breaker is analyzed to find the parameter group of the converter loop which satisfies the system redundancy design under different voltage levels,and the data base is formed under different working conditions.It provides a numerical analysis reference for the study of the dispersion of media restoration.