Transient Global Stability Analysis of Virtual Synchronous Generator

Dissimilar to the conventional synchronous generator, the damping of virtual synchronous generator (VSG) could be flexibly adjusted to build up the dynamic property of the system. The global stability mechanization of VSG system under damping is analyzed. Firstly, the dynamic model of VSG system is constructed, and the stability region of the system is derived based on Lyapunov theory. Secondly, based on energy conservation law, it is found that the energy dissipated by damping is equal to the damping factor multiplied by the area surrounded by the system trajectory and x-axis in the phase plane. When the damping energy dissipation in each period is greater than the change of potential energy, the kinetic energy of equilibrium point which is unstable decreases monotonously, and the VSG system can achieve global stability. Simulation based on PSCAD / EMTDC verifies the correctness of the proposed global stability condition.