Low Capacitance STATCOM Based on Cascaded Symmetrical Half-bridge Converter
The cascaded H-bridge type static synchronous compensator(STATCOM)is known for its high modularity,reliability,and excellent output harmonic characteristics.However,it is limited by the voltage fluctuation requirements of the DC capacitor,which necessitates the use of large capacitance capacitors for the submodules,thereby hindering the achievement of high-power density in the converter.To reduce the cost and size of the STATCOM,this paper presents a novel low capacitance cascaded symmetrical half-bridge STATCOM.This solution significantly reduces the capacitance value of the submodules and the number of switches.By investigating the characteristics of DC-side capacitor voltage fluctuation under low capacitance conditions,an analytical relationship between the capacitance value,voltage fluctuation magnitude and output reactive current is established.Furthermore,a method for selecting the DC-side capacitor is proposed to maximize the utilization of the DC voltage.A control strategy for regulating the peak and valley values of the voltage fluctuation as well as ensuring the control of DC total voltage and submodule capacitor voltage equalization is developed.The operating range of the STATCOM in capacitive and inductive reactive modes is analyzed,establishing the correlation between the operating range and the upper limit of capacitor voltage fluctuation.Finally,Simulation and experimental results are provided to validate the correctness and feasibility of the proposed capacitance reduction method and control strategy.
symmetrical half-bridgeSTATCOMlow capacitanceDC voltage control
万方数据
维普
