Impedance-Based Online Stability Monitoring and Control of VSC-Based Power Systems

This paper proposes an impedance-based online stability monitoring and control method for VSC-based power systems. Specifically, the impedance model of the VSCs and the grid are constructed analytically for the operating points of the system at predetermined time intervals. Thereafter, using the dominant zeros of the determinant of the closed-loop admittance of the system, the so-called loop admittance-based stability criterion is utilized for real-time online monitoring. A higher-level control layer is augmented to adjust the power set points of the VSCs when the system approaches instability to ensure a stable and reliable operation. The effectiveness of the proposed method is verified on a VSC-based network with time-domain simulations in MATLAB/Simulink.