Sensorless control for wind energy conversion system (WECS) with power quality improvement

This paper presents a sensorless control of dc bus voltage of inverter and speed and rotor position of permanent magnet synchronous generator (PMSG) using the extended Kalman filter (EKF) for wind application. The analysis and modeling of a variable speed wind turbine (VSWT) based on PMSG connected to the grid are developed. The system consists of a VSWT/PMSG, three-phase insulated-gate bipolar transistor (IGBT) based rectifier, a three-phase IGBT based inverter and three-phase four wires (3P4W) nonlinear unbalanced load connected to the grid. The PMSG control strategy combines the maximum power point tracking (MPPT) approach and the EKF algorithm. For three-phase grid side converter, an indirect control is applied to give the improved quality of electrical energy at the grid under varying wind speed and pitch angle and to deliver the energy from VSWT/PMSG to the grid ensuring the supply of 3P4W nonlinear load. The ac grid supplies the energy to a 3P4W nonlinear unbalanced load in case of an unavailability of wind energy. To set the neutral current of grid to zero, the fourth wire (4W) for neutral of the load is connected to the midpoint of the two capacitors. Matlab©/Simpowersystem© simulation is performed to prove the effectiveness of the proposed approach.