Study On Cutting-In Control Policy Of Variable Speed Constant Frequency Double Fed Wind Power Generation System

As a kind of new energy sources, wind power generation is a wide source, and non-pollution novel energy, therefore, wind energy is one of the most competitive and promising renewable energy sources in the world. Now the energy used in power generation is playing an important role in energy supply. Studying the wind power technology will have great significance on China-megawatt wind turbine localization, and it will promote the continuous development of Chinese wind power business.Firstly, this paper describes the status of development of wind power in china and world. Several kind of wind turbines and converters which are commonly used in the world are listed, and the future direction of development of wind power technology is also predicted. This paper introduces the development of auto disturbance rejection technique, and on the basis of the high-order and second-order auto disturbance rejection controller (ADRC), designs a more useful ADRC of first-order.Secondly, the control method of grid-side converter was improved. The grid-side converter is a nonlinear, multivariable, strong coupling system, and is sensitive to external disturbances and to perturbations in system parameters. Traditional PI combined with vector controller in the grid-side converter is of the advantages of high power factor, low harmonics of AC side and simple algorithm, but when there is a disturbance or perturbation, the control effect is not ideal. To solve the problem, the paper designs a first-order active disturbance rejection controller (ADRC) to improve the traditional control strategy, including integrating the external disturbances and perturbations in system parameters as a total disturbances by using the extended state observer(ESO), then using nonlinear feedback control method to control grid-side converter. The simulation results show that when a disturbance or perturbation occurs, the improving control strategy has stronger robustness than the traditional control strategy, and the control results are satisfactory.Finally, to solve the problem that the traditional PI combined with vector controller does not conduct an ideal control effect when wind power generator connects to grid and the disturbance occurs simultaneously in the system, the paper designs a first-order nonlinear ADRC to improve the traditional control strategy. The model of VSCF double-fed wind power generation was established by using Matlab. The simulation results prove that the no-load grid-connection scheme proposed in the paper is relatively ideal, and the active power, the reactive power can be decoupled. Compared with PI controller, auto disturbance rejection control shows better dynamic response.