Research On Fractional Order Control Technology For Wind Power System

With the development of industry and technology, there requires higher demands for the control accuracy and flexibility in the control area. The fractional order control theory is derived from the theory of fractional calculus's application in the control area. A variety of new forms of controllers have been developed from this theory. And the PIλDμcontroller is one of these new controllers. With the increase of wind turbine capacity and the scale of wind farms, the wind power has more influence on the power system. Hence, the optimization of wind power control technology and applications of new control strategies have always been an important issue. In this paper, based on the fractional order control theory, the fractional order control strategy is applied in wind power system and its control technologies in order to improve control performance and enhance the robustness of the system by designing its parameters appropriately. The following contents are the main work of the thesis:To solve the problems of more design parameters and complexity in fractional PIλDμcontroller design, the method of applying intelligent optimization algorithm is researched. The methods of designing PIλDμcontroller based 0on gentic algorithm and bacterial forging algorithm are given in detail. A PIλDμcontroller is designed for an actual speed regulation system based on bacterial forging algorithm. The simulation results show that, compared with the tradtional integer order control strategy, the designed fractional order PIλDμcontroller has better control performance, and it can well suppress the exogenous perturbation to the system in case of system model uncertainty with better robustness.To realize the maximum wind energy tracking of PMSG(permanent magnet synchronous generator)-based wind energy conversion system(WECS), the fractional order PIλcontrol strategy is proposed. And the genetic algorithm is applied for the parameters tuning. The simulation results show that, the wind turbine operates with the best tip ratio speed under rated wind speed. The proposed control method has better control performance. To achieve the pitch control of wind power system, the entire linearization model of the system is established and the method of designing PIλDμcontroller based on bacterial forging algorithm is introduced, which makes optimization tuning for the five control parameters. The simulation results indicate that the proposed control strategy can effectively realize the control objective with better control performance.The novel control strategy of applying fractional order PIλcontroller based on genetic algorithm for the double-loop control system of static synchronous compensator(STATCOM) is proposed. The simulation results indicate that the control performance of STATCOM is effectively improved. The reactive power compensation and voltage control of the wind farm with STATCOM is researched further. The simulation for the system is carried out with or without STATCOM and when fault occurs. The results show that the STATCOM can effectively provide reactive power for the wind farm. The voltage stability is improved in case of the randomicity and fluctuation of wind speed. The security and stability of the wind farm are improved.