Operation analysis of dual three-point SVG

As an important part of SVG the inverter works largely on the stable voltage crossing the capacitor of DC-link circuit and the pulse-control of power elements. The introduced control strategy in this paper is about the control of reactive-power, which follows through the transmission line, and the DC-link voltage, which is regarded as inner control loop for a desired level to produce a stable output-voltage. With this control strategy the control system can easy send reactive-power to system or absorb reactive-power from system, and hence, stabilize terminal-voltage. The reactive dynamic characteristics are discussed as load-property varies abruptly from inductive to capacitive, or put off/on inductive load. Especially, the transition processes of voltage and current of power elements are described in detail.