Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems

This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb&Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P&O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter.