Research on Transient Stability Domain Estimation of VDCOL Control of HVDC System Based on Polynomial Lyapunov Function

In current modern power system, high voltage direct current (HVDC) transmission is crucial, the stable operation of HVDC has become a prerequisite for the power system's stability. In order to avoid further commutation failure, HVDC generally enters the VDCOL control mode after experiencing one. Therefore, the transient stability (TS) of the VDCOL control mode determines the reactive power dynamic characteristics of the receiving-end power system. Firstly, this study presents the fundamentals of VDCOL control and HVDC systems. Then, this study proposes a TS domain estimation approach for VDCOL control of HVDC based on the nonlinear model of AC/DC hybrid system. This method constructs the polynomial Lyapunov function of the AC/DC system with VDCOL control mode and performs corresponding stability domain estimation. Finally, case studies of IEEE 9-bus system with line-commutated converter HVDC(LCC-HVDC) in MATLAB are simulated and the simulation curves demonstrate the TS domain estimation method's efficacy.