A new HVDC transmission system based on the new converter transformer is analyzed. The tap at the linking point of the prolonged winding and the common winding of the secondary windings is connected with the LC resonance circuit. There will be no inductive harmonic current in the primary winding. Moreover

the active power that the converter needs can be partly compensated in the secondary winding. Finally

the PSCAD / EMTDC simulation tool is used to study the dynamic recovery performance of the new and convention HVDC system adopting several different var compensating devices in HVDC inverter-Fixed capacitor（ FC）

static var compensator（ SVC） when HVDC are subject to various typical faults.