Energy-based Robust Adaptive Control Of Wind Power Conversion Systems

In order to tackle the problem of the global ecological environment deterioration and the exhaustion of petrochemical energy, the researching and usage of new energy caused whole world attention. The wind power technology is one the most rapidly developed technology, in which the permanent magnet direct drive wind power system has been widely used because of the advantages of simple structure, low fault rate, high power generation efficiency and reliability. However, the wind power conversion system has the characteristics of strong nonlinearity and high uncertainty. It is significant to adopt effective and reliable control strategies to improve the utilization efficiency of wind power and to enhance the stability and reliability of system. In this dissertation, the energy-based robust adaptive control problem of the permanent magnet synchronous wind power conversion system is investigated via Hamiltonian system theory. The main results can be summarized as follows:(1) Based on the permanent magnet synchronous wind power conversion system, the overall structure is analyzed and the structures of various components are described in detail. Then, the mathematical model of wind turbine, drive mechanism, permanent magnet synchronous generator and pitch control mechanism are established.(2) Energy-based maximum power point tracking control of permanent magnet synchronous wind power conversion system below the rated wind speed is studied. Firstly, nonlinear uncertain dynamic model of the system is established and it is transformed into Hamiltonian system model. Then, feedback control strategy is adopted to realize the reconstruction of the Hamiltonian function and configuration of the desired equilibrium. Finally, based on energy and the structure characteristics, the robust adaptive controller is designed which can capture maximum wind energy of the system. Simulation results demonstrate that under the parameter perturbation and external disturbances, the proposed controller can capture wind energy of maximum under random wind speed.(3) In order to ensure the whole wind power conversion system can operate safely above the rated wind speed, the energy-based robust adaptive constant power control problem of the permanent magnet synchronous wind power conversion system is studied. Firstly, variable pitch control loop and permanent magnet synchronous wind power conversion system are combined and the mathematical model of the system is established. Then, the state feedback controller is adopted to re-assign the equilibrium point and realizes the reconstruction of the Hamiltonian function and structure matrix. Finally, an energy-based robust adaptive control strategy is constructed by using the internal structure characteristic of system. The rotor speed can be adjusted and maintained at rated value by changing of pitch angle. The constant power control of the wind power conversion system above rated wind speed is realized. The simulation results show the effectiveness of the proposed control strategy.