Evaluation Method of Static Voltage Stability in Multi-infeed HVDC System during Power System Restoration

Abstract

Considering the coordination of restoration path selection and power recovery control, this paper proposes a static voltage stability evaluation method for multi-infeed HVDC (MIDC) system. Firstly, a multi-infeed comprehensive short circuit ratio (MISCR) index is applied to evaluate the voltage stability at the converter bus. The continuous power flow method is used to evaluate the static voltage stability margin of other AC nodes, which can not only be used as the safety constraint of power recovery, but also give the weak nodes of the system and guide the power recovery control. Then, the influence of restoration path on HVDC support capability is studied, a multi-infeed short circuit ratio offset (MSCRO) index is proposed to optimize the restoration path. When the restoration path is determined, MISCR can be used to calculate the maximum DC power that can be accessed and the voltage stability margin is obtained by continuous power flow method. Therefore, the purpose of making use of DC power to speed up the recovery process and ensure the safety of recovery is achieved. The IEEE 39 buses test system is taken as an example to verify the feasibility and effectiveness of the proposed method.