Investigations on a 5-level VSI-chopper for a superconductive magnetic energy storage (SMES) power conditioning system

The introduction of multilevel converters makes possible the use of pulse width modulation (PWM) converters and medium power devices like insulated gate bipolar transistors (IGBTs) for high-voltage, high-power applications, such as flexible ac transmission systems (FACTS). This paper proposes a 5-level voltage source inverter-chopper topology for a superconductive magnetic energy storage (SMES) power conditioning system (PCS). The topological structure and operation principles of 5-level VSI and 5-level chopper are discussed. The performance of the proposed converter system has been compared with a traditional transformer coupled multi-pulse VSI-chopper topology. The application of the proposed 5-level SMES PCS to static var compensator (SVC) has been investigated and verified by computer simulations.