A Novel PCS Control Strategy for SMES to Suppress Overvoltage of Magnet

In SMES with Voltage Source Converter (VSC), the DC/DC chopper applies high-frequency PWM voltage to the superconducting magnet. This PWM voltage will not be averagely distributed in the magnet, which will harm the insulation of the magnet. This paper redesigns the control strategy of the power conditioning system (PCS): during SMES charging or discharging, SMES magnet withstands continuously changing DC voltage rather than high-frequency PWM voltage. This control strategy fundamentally avoids the harm of uneven distribution of high-frequency PWM voltage in SMES magnet. Firstly, this paper introduces the circuit principle of this control strategy. Secondly, the power operating range of VSC while using this control strategy is analyzed. Thirdly, the simulation of SMES using this control strategy is built. Finally, this paper simulates the voltage distribution of SMES magnet using different control strategies. It is proved that this control strategy can reduce the transient distributed overvoltage of SMES magnet.