Voltage and frequency control of wind-powered islanded microgrids based on induction generator and STATCOM

This paper presents a comprehensive modeling of a three-phase cage induction machine used as a self-excited squirrel-cage induction generator (SEIG), and discusses the regulation of the voltage and frequency of a self-excited SEIG based on the action of the static synchronous Compensator (STATCOM). The STATCOM with the proposed controller consists of a three-phase voltage-sourced inverter and a DC voltage. The compensator can provide the active and reactive powers and regulate AC system bus voltage and the frequency, but also may enhance the load stability. Moreover, a feed forward control method for the STATCOM is introduced and applied for controlling the SEIG´s terminal voltage using a two-degree of freedom RST controller. Simulation results for the steady-state operating condition and transient operating conditions for the system subjected to a wind reference step change, and a step load change are presented to demonstrate the effectiveness of the proposed controller.