Transient stability of power system integrated with doubly fed induction generator wind farms

A new quantitative assessment of transient stability for power systems integrated with doubly fed induction generator (DFIG) wind farms is proposed by evaluating the transient energy margin (TEM) through the formulation of the transient energy function (TEF) for multimachine systems. To achieve an accurate TEM, the TEF is modified to account for the separation of the critical machines from the system and an unstable equilibrium point is calculated on the basis of post-fault trajectory reaching the potential energy boundary surface. Simulation results show that such power systems integrated with DFIG wind farms are more sensitive to transient events of higher voltage sag, longer fault clearing time, lower load operation and higher wind power penetration level. It is also observed that machines located far from the fault are also exposed to inferior transient stability because of fault with geographical dispersion of wind farms. As a result, advanced switchgear, faster isolators, more efficient power reserve systems and advanced reactive power compensating devices must be equipped to ensure reliable operation of power systems integrated with the DFIG wind farms during transient events.