Simulation And Interrupting Test Investigation On Mechanical DC Vacuum Circuit Breaker

Direct current(DC)circuit breakers that can quickly clear short-circuit faults are an important protection device for DC transmission system.With the development of rapid electromagnetic actuators,mechanical DC vacuum circuit breaker can meet the technical requirements of DC circuit breakers.This article takes the mechanical DC vacuum circuit breaker as the research object,adopts active inject method,and then conducts the DC vacuum circuit breaker simulation and experimental research.This article takes the mechanical DC vacuum circuit breaker as the research object,adopts the active injection method,researches the simulation and test of the DC vacuum circuit breaker interrupting process.In order to conduct the interrupting test of the DC vacuum circuit breaker,it is first necessary to build a test platform.The most important part is the design of the DC vacuum circuit breaker control system.Due to the need to isolate the test personnel from the high voltage of the test platform,a fiber isolation circuit is designed.The operating mechanism of the DC vacuum circuit breaker is a permanent magnet and repulsion mixing mechanism.Their actions require the discharge of the capacitance to be completed.Therefore,a capacitance charging and discharging circuit and a circuit that discharge to coils are designed.In order to ensure the safety of the personnel and the voltage value of the capacitor is stable,the capacitance charging is controlled by infrared remote control.When the capacitor discharges to the permanent magnet or the repulsive coil,taking into account the heating of the coil,the formula for calculating the maximum current that the coil can withstand is deduced.Then the average speed of each switch of the DC vacuum circuit breaker is measured,and the test results show that the opening and closing speed of each switch can meet the test requirements.The main switch and the commutation switch of the DC vacuum circuit breaker are composed of two vacuum interrupters in series.Therefore,the non-synchronism of the opening of the main circuit breaker and the closing of the commutation switch are measured,and the non-synchronism of the main circuit breaker is 200?s,and the non-synchronism of the switch closing is 162?s.Simulation models under system conditions and experimental conditions are built by using Matlab/Simulink simulation software,and simulation results are studied and analyzed.Comparing the simulation results under the two conditions with the theoretical calculation results in the ideal working conditions,the reasons for the difference in simulation results under the two conditions is analyzed.Based on the calculated switching time sequence,a preliminary breaking test is performed on the DC vacuum circuit breaker on the experimental platform.The test results show that the DC vacuum circuit breaker not only successfully interrupts the current of 7kA,but also the recovery voltage distribution of the two switches of the main circuit breaker is relatively uniform,and it is basically same with the simulation result.Through the waveforms acquired after the failure of the test,the reason for the failure of the test is studied,and experience is accumulated for the subsequent tests.