Application of finite-time control Lyapunov function in low-power PMSG wind energy conversion systems for sensorless MPPT

摘要

This paper discusses the problem of observer-based finite-time control (FTC) of a grid-connected wind turbine and a low-power permanent magnet synchronous generator (PMSG). An adaptive nonlinear observer is employed to estimate the mechanical variables. Maximum power point tracking (MPPT) is obtained using the estimation of rotor speed and torque from the adaptive observer, and excluding the wind speed sensor. Improvement of the MPPT technique through the designed FTC is investigated. The proposed controller stabilizes the WECS and tracks the reference trajectories in a short pre-known time alternative to common nonlinear controllers with large settling time. The suggested controller is also robust against uncertainties in WECS parameters. Parameters’ variations are compensated by robust control design. Finite time stability and robustness of the proposed WECS controller is mathematically proved. Moreover, the advanced performance of the suggested FTC is demonstrated by simulation and is compared to a conventional asymptotic convergent controller (ACC). The proposed FTC provides fast and robust rotor speed regulation and thus enhances the sensorless MPPT. The proposed FTC improves the WECS performance for tracking of ramp references and robustness against parameter uncertainties. Furthermore, advanced control of the grid-side converter yields improved resiliency and reliability.