Topology Research of Static Reactive Compensator Based on Cascade Multilevel Converter
Real-time reactive power compensation of a power system is very important to improve power quality.The traditional reactive power compensation often uses large-capacity reactors and capacitors,which are large in vol-ume,heavy in weight and low in efficiency.The static reactive compensator is composed of fully controlled switching devices,which has the advantages of controllable,fast dynamic response,low loss and high efficiency.The cascaded multilevel converter,which takes single-phase H bridge as the cascaded unit in series,can output multilevel wave-form,improve the sinusoidal degree of output voltage,reduce the harmonic content,and reduce the volume of filter through phase shifting control of each H bridge.Moreover,it has the advantages of strong scalability,strong adapta-bility and easy implementation.This paper introduces the topology and working principle of cascade multilevel con-verter.Then the PWM modulation strategy based on the triangle carrier phase shifting technology is introduced to re-duce the switching frequency of the switching tube and improve the efficiency of the system.Finally,a simulation model is built to verify the effectiveness of the topology and modulation strategy.
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