Control of grid-side inverter for isolated wind-diesel power plants using variable speed squirrel cage induction generator

This paper is a step towards the dynamic modelling and control of complete wind/diesel generation system for islanded areas. It mainly focuses on the control strategy of the grid-side inverter usually used in variable speed wind turbines connected in cogeneration schemes. The considered conversion system is equipped with a geared squirrel cage induction generator (SCIG). The developed control strategy is based on the voltage oriented control (VOC) of a 3-phase inverter connected to a weak grid. The controller´s PI regulators are designed using the classical direct synthesis approach and cascade control loops technique in the synchronous dq- reference frame. A grid voltage regulation loop, widely used in D-STATCOM systems is designed to add the automatic reactive power management feature to the inverter. Various simulation results using Matlab/Simulink^® software for different system´s contingencies such as sudden step changes of the wind power are presented. The reactions of the system to step changes in grid voltage, due to the small size of the considered grid, are also presented and extensively discussed.