Energy Variation Rate-Based Transient Stability Analysis Method for VDCOL Control of HVDC Transmission System

During the recovery process of commutation failure, the current command repeatedly enters and exits the voltage dependent current order limiter (VDCOL) control because of the interaction between the DC regulation speed and the AC voltage recovery rate, causing the DC power to oscillate continuously. Concerning this problem, a transient stability analysis method of VDCOL control based on energy variation rate is proposed. Firstly, the paper analyzes the VDCOL control during the recovery process of commutation failure and constructs the voltage recovery equation of the receiving-end power grid. Secondly, according to the model of receiving-end power grid and voltage recovery equation, the energy function is established, and the transient stability of the system during the recovery process of commutation failure is revealed based on the analysis of energy variation rate of DC terminal (in VDCOL control) and other components. Finally, the transient energy trend of the receiving-end power grid is analyzed by building a commutation failure and recovery simulation, and the simulation results illustrate the effectiveness of the proposed transient stability analysis method.