Impact of DFIG with phase lock loop dynamics on power systems small signal stability

With increased penetration of wind power, the impact of doubly fed induction generator (DFIG) on small signal stability of power systems gains more and more attention. Control of DFIGs depends on accurate phase lock information of DFIG terminal voltage from phase lock loop (PLL). This paper carefully evaluates the influence of PLL dynamics and steady-state error on low frequency oscillation using an analytical approach based on eigenvalue analysis. Simulation results show that PLL´s steady-state error hardy influences the small signal stability while dynamics of PLL could change electromechanical eigenvalues of power systems with certain PI parameters. PLL´s state variables could participate in low frequency oscillation.