Wind-Speed Estimation and Sensorless Control for SPMSG-Based WECS Using LMI-Based SMC

In this project, to enhance system reliability and to reduce the cost and complexity of a Surface-Mounted Permanent-Magnet Synchronous Generator (SPMSG)-based variable-speed direct-drive Wind-Energy Conversion System (WECS), an efficient wind-speed estimation method and a sensor less rotor-position/speed control method is proposed.  To estimate the rotor position of an SPMSG, Sliding Mode Control (SMC) based Linear Matrix Inequality (LMI) strategy is proposed. 

This method depends on measured electrical quantities, such as stator voltages and estimated stator current error, to evaluate the back electromotive force components, which are used to estimate the rotor position. The rotor speed is assessed according to the rate of change of the estimated rotor position. 

The wind speed is estimated by estimating the back propagation power flow according to the nonlinear dynamical power wind-speed characteristics of the wind turbine. In estimating the rotor position, the proposed LMI-based SMC design provides good steady state and dynamic performances under all operating modes of the WECS. The proposed control schemes are validated by simulating a test system, i.e., a 250-kW SPMSG-based WECS, in MATLAB/Simulink.

Keywords: Back electromotive force (BEMF), linear matrix inequality (LMI), sensor less control, sliding mode control (SMC), surface-mounted permanent-magnet synchronous generator (SPMSG), wind energy conversion system (WECS).