The Research Of Multi-Level Voltage Reinjection Voltage Source Converter

High power AC/DC converters based on forced commutated power switches provide attractive performances and flexible controllability for HVDC ( High Voltage Direct Current) and FACTS (Flexible AC Transmission System) applications.The high power forced-commutated converters provide potential application for power transmission and distribution system. The thesis describes a new configuration of Multi-level voltage reinjection VSC(MLVR-VSC) with reinjection H-bridge chain for voltage renjection.The new concept of MLVR-VSC is a combination of the multi-level, soft switching and reinjection conversion concepts. The MLVR-VSC is to provide a solution of dynamic voltage balancing for direct series connected switching devices to form high voltage valves, to reduce the harmonic content to produce high quality waveforms, to improve the conversion efficiency and reliability by using low switching frequency and soft switching conditions for main bridge switches.The operating principle of the proposed configuration and the control circuitry implementation are presented. The control circuitry is constructed around a DSP(digital signal processor), which provides gate driving, converter voltage and current detecting, logic level converting and protecting functions. The implemented MLVR-VSC as a model can be directly connected to power grid as a STATCOM.