Dynamic reactive power characteristic analysis of inverters under the commutation failure faults in HVDC systems

Abstract

In the traditional high voltage direct current (HVDC) systems, commutation failure (CF) fault is one major challenge, and the transient var characteristic of the inverter station is an essential factor in the counter measures against CF fault. Based on the detailed switching process of valves during CF, the var demand characteristic is analysed. From the key factors during the recovery of CF, the dynamic var demand characteristic is investigated. It is shown that, the dc side of converter is short-circuited and the ac side can be regarded as open-circuit. Moreover, the var demand of inverter station is mainly influenced by the changing ratio of dc current and commutating voltage. At last, the case studies verify the validity of the reactive power characteristics of the inverter station proposed in this paper.

Keywords

• Dynamic var demand
• Commutation failure
• HVDC