Impacts of doubly-fed wind turbine generator operation mode on system voltage stability

The choice of Doubly-fed induction generator (DFIG) operation strategy has a significant impact on voltage stability. Now there are two types including constant-power factor and constant-voltage control and their essential differences are different control strategies between the scheduling of reactive power and voltage control. The article presents control strategies of wind generator on two kinds of operation modes after establishing a simplified dynamic model of DFIG, and then utilizes static continuation power flow techniques (CPF), quasi-static time domain simulations (QTDS) and time domain simulations (TDS) to investigate their impacts on system stability. The simulation results show that both of control modes can maintain system voltage within a limited range in the changing process of wind power penetration. In addition, due to taking full advantages of DFIG reactive power regulation function constant-voltage control has a greater advantage than constant-power factor control on improving the system voltage stability.