Research On Double Capacitor Hybrid DC Circuit Breaker And Its Control Method

Due to the rapid socio-economic growth in recent years,the country' s dependence on power resources has been further strengthened,and as the disadvantages of long-distance high-voltage AC transmission lines have become increasingly prominent,more and more scholars have begun to study long-distance and direct-current power transmission.Therefore,the requirements of circuit breakers have also increased.In this paper,based on the analysis of the development status the methods and principles of DC breakers,A two-capacitor hybrid DC circuit breaker topology and control scheme are proposed.In this paper,in addition to the pre-charging capacitor C1,a voltage divider capacitor C2 is added.This design can accelerate the DC circuit breaker breaking speed by reducing the reverse charging and reverse discharging of the pre-charging capacitor.In addition,the secondary arcing problem caused by the excessive reverse voltage at the instant of opening the high-speed mechanical switch is solved by adding a freewheeling loop.By adding a charging circuit,the disadvantages of the pre-charging capacitor requiring additional power charging are solved.In this paper,detailed mathematical formulas are deduced for each critical stage in topology operation,and the correctness of mathematical derivation results is verified by MATLAB/Simulink simulation results.Comparing the topology of this paper with the single-capacitor DC circuit breaker in the same simulation environment can more directly highlight the advantages of the topology design of this paper.After the design of the control scheme,the topology of this paper can meet the breaking requirements of DC circuit breakers for large voltage and large current in hardware.The comprehensive analysis shows that the topology model is in line with the working principle of DC circuit breaker and can quickly and safely break the DC system in 2.7ms,which is theoretically feasible.