The Study On Active And Reactive Power Decoupling Of Doubly-Fed Variable Speed Constant Frequency Wind Generator

With the increase of energy problems, wind energy as a renewable energy has aroused people's more and more attention. Wind power generation technology also became the scholars'hot spot of the research all over the world. With the characteristics of low cost, highly efficiency, adjustable power convenient, variable speed constant frequency (VSCF) of doubly-fed wind power generator system has became the mainstream of the world. Currently, active and reactive power decoupling control of doubly-fed inductor generator (DFIG) is the key and difficulty in the field of wind technology.This paper, starting from the basic theory of wind turbine and DFIG, is about the research of DFIG and its power decoupling control technology. First, a theoretical analysis for wind turbine and DFIG is processed, mathematical models in different TRS are given. Then a double-closed-loop control model of DFIG based on stator-flux-oriented is constructed in order to achieve active and reactive power decoupling control. On this basis, the PI adjuster of the current regulating loop and outer power (speed) regulating loop was designed, Kp and Ki designing principles of double-closed-loop decoupling control system were given, PI parameters of DFIG can be estimated if known the motor parameters.Aiming at the problems of the conventional PI controller, such as difficult to adjust PI parameters of outer power (speed) regulating loop and poor dynamic performance, a Fuzzy-PI controller is presented to replace the outer power (speed) regulating loop. A comparison between the developed vector controller with the proposed Fuzzy-PI strategy and the traditional vector controller with the conventional PI strategy has been done in three different wind resources. Finally, the proposed strategy was verified through a semi-physical experiment platform. Both the simulation and experiment results show that using the Fuzzy-PI controller can realize the power decoupling of DFIG, improve the dynamic performance of the system, good robustness, and small overshoot.