Fast Voltage Stabilization Evaluation Method for HVDC Project with Weak Contact Channels in Sending Terminal Based on Short Circuit Capacity

Abstract

In the initial operation stage of some HVDC transmission systems in China, the DC power supply and some electric equipment has not put into service; the power transmitted by HVDC project all comes from AC system; Therefore disturbances from both AC and DC system can cause serious voltage stabilization problem. On the one hand, if the components connecting AC and DC system loss, the connection between the two system will be further weakened and the voltage in converter station may be unstable. On the other hand, when large disturbance occurs in DC transmission system, the bus voltage of converter station may experience severe transient overvoltage resulting from the surplus of reactive power. This paper proposes a fast evaluation method of voltage stability for HVDC power grid with weak contact channels in sending terminal based on short circuit capacity. The method formulates the relation between short circuit capacity and static voltage stability limit as well as that between short circuit capacity and bus voltage. Taking Zhalute-Guanggu HVDC as an example, this article analyzes the mechanism of transient overvoltage and voltage instability at converter bus and evaluates the voltage stability of the project using the proposed method. The computing results verify the correctness of the analysis method. The method described in this paper is concise and effective enough to be applied to other high-capacity HVDC system.