An Analytical Tool for Computing Transient Stability Margins of Power Systems with Large Amount of Wind Power

This paper presents an efficient method to calculate the transient stability margin of power systems with a high penetration of wind power. Critical clusters of coherent generators are determined for each three-phase fault. The coherence criterion employed is the angular speed deviations observed during and post-fault system trajectories. The reduced order is obtained by replacing two groups of coherent generators by a Single Machine Equivalent (SIME). With the electromechanical equivalent formed, critical fault clearing times and security margins are calculated by using the well-known equal-area criterion. The method was tested on a real power system with ten hydro and thermal units and nine hypothetical variable speed direct-drive synchronous generators wind farms. The results are very close with those obtained by using the integration method. It is demonstrated that the method can be applied for operation and planning of power systems with a large amount of wind power.