Fault tolerant adaptive sliding mode controller for wind turbine power maximisation

This paper presents a new approach to robust fault tolerant control (FTC) to optimise the wind energy captured by a wind turbine in the low wind speed range of operation, using Sliding Mode Control (SMC). In addition to the inherent robustness of SMC against matched model parameter uncertainty, the proposed method can first tolerate generator speed sensor faults and generator torque bias faults. Secondly, the need for a state observer can be removed by using the SMC robustness property and by adapting its switching gain so that the unmeasurable signals are compensated. The sliding surface is designed to achieve the required objectives by utilizing the nonlinear equation of the flexible two mass model of variable speed wind turbine. The proposed FTC SMC method is applied to a 4.8MW wind turbine benchmark model and the results are compared with equivalent results obtained from a “standard controller” (SC).