Research on Fast Switching Technology of Dual Power Supply for 10kV Induction Motors

The existing 10kV induction motors are widely used in industrial production, medical treatment, transportation, and other important fields. More than 30ms of power interruption may cause serious economic losses. The 10kV dual power supply switching technology generally adopts the traditional mechanical switch. The switching time can reach hundreds of milliseconds, and the transient impact is serious. Although power electronic switches can achieve fast switching, there are problems such as limited voltage and current capacity, complex structural control, high cost, and low reliability. In this paper, a 10kV dual power supply switching technology based on a fast vacuum circuit breaker (FVCB) parallel to trigger vacuum switch (TVS) is proposed. After the main power supply is powered off, the FVCB can remove the main power supply within 3ms. The TVS can be reliably and accurately triggered within 1ms. It can quickly clear the fault and switch to the standby power supply within 20ms. It has the advantages of fast switching speed, strong current capacity, and high overload reliability, and overcomes the shortcomings of traditional mechanical switches and power electronic switches. Therefore, this paper analyzes the residual voltage characteristics of typical 10 kV induction motors. A dual power switching model of 10kV induction motors is constructed to explore the influence of the phase angle difference between the standby power supply voltage and the stator residual voltage and the switching time on the transient impact of the induction motor during the arcing process. Finally, the TVS is determined to cooperate with the switching sequence of the FVCB. The optimal power switching strategy is formulated to ensure the safe and stable operation of the induction motors.