Transient stability analysis of AC/DC power system based on PEBS method

A transient energy function with consideration of DC dynamics is constructed for AC/DC power system. As the generator angular speed and rotor angle, the AC bus voltage at DC converter station is explicitly represented in it. It is not assumed that the variables of the transient energy function would change along a linear path from the stable equilibrium point to the exit point on PEBS (Potential Energy Boundary Surface). The angular speed and rotor angle, treated as slow dynamics, are integrated along sustained fault trajectory or disturbance trajectory, but the integral path of the DC dynamics, treated as fast dynamics, are obtained by modification. The application of PEBS method in the calculation of critical energy and critical clearing time are discussed. The critical clearing time is calculated by PEBS method and the time -domain simulation method respectively for 4-machine and 10-machine AC/DC systems, and the results validate its effectiveness.