18-STEP BACK-TO-BACK VOLTAGE SOURCE CONVERTER SYSTEM FOR HVDC APPLICATION

摘要

PURPOSE: A 18-step back-to-back voltage source converter system for HVDC is provided to independently control reactive and active power of an AC system by controlling the size and phase of an output voltage. CONSTITUTION: An open Y-Y transformer(160) boosts or drops AC power. An auxiliary circuit(150) includes a three-level half-bridge(151) and a single phase transformer(155). First and second converters(110,120) are connected in parallel to the open Y-Y transformer and are serially connected to the auxiliary circuit.