基于李雅普诺夫函数的带锁相环的 VSC 大扰动稳定性判据

To study the large disturbance stability of a grid-connected VSC with phase-locked loop, a simplified second order nonlinear model of a VSC is established based on the difference of response speed between inner loop current control and outer loop power control, and two Lyapunov functions are separately defined. The first Lyapunov function has clear kinetic energy and potential energy concepts but a small stable region, while the second Lyapunov function has a wider stable region but lacks clear physical concepts. Combining the two Lyapunov functions, a practical stability criterion is obtained, one which has both clear physical concepts and a relatively large stable region. If the state of the phase-locked loop is known at the time of the system’s last operation, the stability can be predicted. The simulation results well verify the accuracy of the derived stability criterion.