A new control method to realize constant tip speed ratios of series connected wind turbine generators

A new control system for a wind farm consisting of series connected wind generators and a current-source thyristor inverter is proposed. In this type of wind farm since the rectified outputs of all generators are connected in series, the armature currents of all generators become the same. So, it is hard to keep the tip speed ratios of individual turbines constant for any cases of wind conditions. In this paper, a new control method for the wind turbine systems with series connected wind generators is proposed. Constant tip speed ratios can be realized by means of controlling the DC link current at an optimum value. Here, the dynamic performances of the system consisting of plural wind generators are discussed, and experimental investigations are included to confirm the proposed control method.