Research On Nonlinear Adaptive Control Of Doubly Fed Induction Generator

Doubly fed induction generator(DFIG)is one of the main wind generator type in the wind power market.Its improvements of energy conversion efficiency and operation reliability relies on good control strategies.In consideration of the nonlinear coupling natural characteristics of DFIG wind generation system,this thesis proposes a nonlinear adaptive controller based on time delay control(TDC)strategy.TDC strategy defines a perturbation term to describe the combined effect of the system nonlinearities,uncertainties and external disturbances.Then,the time delayed control signal and controlled output signal are utilized to estimate the present perturbation.Finally control signals are generated with the feedforward compensation term and linear system control technique.TDC strategy does not rely on accuracy system models,requires less parameters to be tuned and only requires the measurement of output variables.Firstly,two controllers are designed for maximum power point tracking(MPPT)of DFIG wind generation system based on vector control(VC)and TDC strategies,respectively.The DFIG wind generation system model,whose converters are equivalent to ideal controllable voltage source,and the New England 10-generator 39-bus power system model are built on Matlab/Simulink,and utilized to simulate and compare the control performance of the two controllers.Simulation results prove that TDC controller performs better than VC controller in transient respond and robustness to parameter variation.Then,based on TDC strategy a controller for directly power regulation of DFIG is designed.The DFIG wind generation system model,which takes the switch effect of converters into consideration,is built on Matlab/Simulink,and utilized to test the proposed controller.Simulation results shows that TDC controller performs better in tracking ability and robustness to parameter variation compared with VC controller.