Research on a novel drive unit of fast mechanical switch with modular double capacitors

摘要

The fast mechanical switch is one of the key devices for high-voltage direct-current circuit breakers (DCCB), and the mechanical contacts separation time determines the operating time of hybrid mechanical circuit breakers. With the increasing of the voltage and power levels of DC system, numerous technical challenges begin to emerge. For high-voltage system, the new research and the series arrangements of very fast mechanical switches include designing new drive unit to satisfy larger load mass and longer travel stroke. Aimed to reducing the peak value of electric force, a novel drive unit by using modular double capacitors has been proposed here. Based on the equivalent circuit method (ECM), the mathematical model of Thomson coil (TC) actuator which is the drive unit in fast mechanical switch is established. First, the time sequence of capacitance discharge is studied. Then, the electromagnetic force can be divided into five types in different time sequences, and the characteristics of the electromagnetic force are analysed. Finally, it is concluded that using a combination electromagnetic force with three approximate peaks can reduce the impact of the metal plate, which improve the reliability of the fast switch.