Designing an efficient PI-based voltage control method for squirrel-cage induction generators in islanding/weak grid-connection conditions

Wind farms are normally located far from the grid and, and may often experience islanding or weak grid-connection conditions. In such cases, the control system, which traditionally compensates the reactive power demanded by the generator, should take over the control of the voltage in order to stabilize the load bus voltage. In this paper, a new design of a PI-based controller is proposed to effectively maintain the voltage output of a wind farm consisting of squirrel-cage induction generators (SCIGs) connected to a weak grid, which might also be disconnected. The controller output changes the voltage output of a static synchronous compensator (STATCOM) to regulate load bus voltage. Conventional PI-based control methods are first investigated. Then, a new PI-based controller is designed. The results prove that the proposed new control method has substantial merits compared to the conventional methods.