Sensitivity Model of L Index for Steady-state Voltage Stability of Wind Power Systems with Doubly Fed Induction Generators

Abstract

There is increasing concern for the steady-state voltage stability of power systems with wind power integration. Simplification to wind turbine generators or transmission systems yields inaccurate judgment to steady-state voltage stability. In this article, a detailed configuration of doubly fed induction generators under maximum power-point tracking mode is provided and solved together with power flow equations to derive the L indices of load buses. The sensitivities of L to the bus powers and tap changers are newly proposed to quantify the effect of control measures on steady-state voltage stability. The former does not ignore the line resistance as the existing sensitivity model of the B index; the latter considers the derivatives of the admittance matrix to the tap changer. The numerical results show that the doubly fed induction generators and wind speeds have a notable effect on the steady-state voltage stability. Active load shedding may improve or decrease the steady-state voltage stability, while reactive load shedding improves the steady-state voltage stability. The tap changers may yield opposite effects on different load buses. Compared with the continual power flow, the sensitivity model describes the control measures for steady-state voltage stability with desirable accuracy.