Physics-informed transient stability assessment of microgrids

With the integration of a voltage source converter (VSC), having variable internal voltages and source impedance, in a microgrid with high resistance to reactance ratio of short lines, angle-based transient stability techniques may find limitations. Under such a situation, the Lyapunov function can be a viable option for transient stability assessment (TSA) of such a VSC-interfaced microgrid. However, the determination of the Lyapunov function with the classical method is very challenging for a microgrid with converter controller dynamics. To overcome such challenges, this paper develops a physics-informed, Lyapunov function-based TSA framework for VSC-interfaced microgrids. The method uses the physics involved and the initial and boundary conditions of the system in learning the Lyapunov functions. This method is tested and validated under faults, droop-coefficient changes, generator outages, and load shedding on a small grid-connected microgrid and the CIGRE microgrid.