Application Of Variable Pitch And Intelligent Control For Wind Turbine

With the increase of wind turbine size, unit capacity is also increasing. Most electrical devices requiring a fixed frequency, electric power control requirements to reduce the adverse effects of nets, these factors need to use active control to control wind turbine. Therefore, an increasing number of larger wind turbines are being developed with a variable speed variable pitch control mechanism. The unit can not only increase energy capture, but also improve power quality and regulate drive link and the load on the tower. Flexible control system well improves power quality and the conversion efficiency, the useful life can be extended, which make up for complex structure of variable speed variable pitch wind turbine and the disadvantage of high initial investment.Owing to the stochastic nature of wind speed, time-variable of parameters, system lagging and system nonlinearities the power generated by wind turbines changes rapidly. First, traditional PID variable variable pitch control system and conventional fuzzy variable pitch control system are established. Allowing for the limitations of PID control system and characteristics of wind turbines, 3-D fuzzy variable control system and single neuron variable pitch feedback controller based on fuzzy feedforward are proposed in this paper. In order to obtain good control quality, rules are given by expression formula as rules of multi-dimensional fuzzy controller affect system real-time seriously. And Lagrange interpolation of three-dimensional function is introduced so that it can improve control accuracy through changing discrete variable into continuous variable.Single neuron not only has well self-learning and self-adaptive. Single neuron used in power feedback control can effectively improve the system steady state performance. In additional, redundant wind turbine model and blade is larger inertial, so dynamic control process is extended. Wind detecting instrument is installed in the rear of the cabin. Due to aerodynamic effects, the quality of measured wind speed can not be guaranteed. While measurement of wind speed there is economic problem, so fuzzy feedforward controller based rotor speed is proposed to further improve performance of output power. Both control quality and the real time of system are improved. Simulation results show that three-dimension fuzzy controller and single neuron variable pitch feedback control system with fuzzy feedforward improves control quality and has more excellent adaptability and robustness than PID control system.