Abstract
To enhance system reliability and to reduce the cost and complexity, this paper presents an efficient wind-speed estimation method and a sensorless rotor-position/speed control method for a surface-mounted permanent-magnet synchronous generator (SPMSG)-based variable-speed direct-drive wind-energy conversion system (WECS). In this regard, sliding mode control (SMC) based on a linear matrix inequality (LMI) is proposed to estimate the rotor position of an SPMSG. 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 backpropagation 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. The results confirm the effectiveness and correctness of the designed control schemes in estimating and tracking the actual rotor position/speed and wind speed with trivial errors.
Highlights
To satisfy the growing demand for energy, the dependency on ecofriendly renewable energy sources is increasing remarkably [1]
Enhancing the system reliability and reducing the complexity and cost were the ultimate objectives of this study; these were achieved by 1) developing an efficient scheme for wind-speed estimation without a measuring device and 2) developing a sensorless control scheme for a surfacemounted PMSG (SPMSG) incorporated into a direct-drive variable-speed wind-energy conversion system (WECS), in which no rotor-position/speed sensors are needed
In support of the theoretical explanation and mathematical modeling of the proposed algorithms for wind-speed estimation and sensorless control for an surface-mounted permanent-magnet synchronous generator (SPMSG) presented in Section III, extensive numerical simulations are performed in MATLAB/Simulink
Summary
To satisfy the growing demand for energy, the dependency on ecofriendly renewable energy sources is increasing remarkably [1]. Enhancing the system reliability and reducing the complexity and cost were the ultimate objectives of this study; these were achieved by 1) developing an efficient scheme for wind-speed estimation without a measuring device and 2) developing a sensorless control scheme for a surfacemounted PMSG (SPMSG) incorporated into a direct-drive variable-speed WECS, in which no rotor-position/speed sensors are needed. A sliding mode control (SMC) method based on a linear matrix inequality (LMI) is proposed and is developed with an adjustable SPMSG model for rotorposition estimation to efficiently track the actual position. First, the Lyapunov stability is studied, which permits to develop the core of this section: the stability analysis of the closed system
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