The Control Technology Of The Rotor-side Converter Of The Double-fed Vscf Wind Turbine

It is of great significance to develop and utilize wind power, which is not only renewable but also without pollution when energy source scarcity and environment pollution are getting more and more serious, wind power generation technique is improved greatly so that more and more countries all over the world play attention to it. With the increasing scale of wind power generation system, the investigation on wind generation technique has been focused on improving the operation efficiency of wind power generation. For this reason, the technique of variable speed constant frequency operation capable of capturing the maxim wind power becomes research hotspot.In this paper, based on the operation and control of the AC-excited variable speed constant frequency wind power generation system. The comprehensive, in-depth study is carried out from theory to practice and from simulation to test. the operation theory of the DFIG (doubly-fed induction generation), active and reactive power decoupling control, connected-grid control and LVRT (low-voltage through technology) are studied. a number of important conclusions and some innovative results also are derived.Firstly, in this paper, the operation theory of the DFIG is analyzed. the DFIG mathematical model, frame transformation, and operation characteristics and power relationships of the DFIG are derived from theory, When the full-text research theoretical basis has been laid.Secondly, based on the DFIG mathematical model, several common vector control methods are derived, but also derive control strategy on condition that the power grid voltage failure and the stator magnetic field angle compensation theory.Finally, based on the analysis of existent techniques of wind generator grid-connection, this dissertation discusses the grid-connection control principle which fits for the occasion of AC excited VSCF generator, and two kinds of control schemes called grid-connection control with no-load and grid-connection control with isolated load are put forward.In simulation studies, based on the establishment of the DFIG simulation model, the complete AC-excited variable speed constant frequency wind power generation system simulation model is built, the "time-sharing"work of the two sub-system(connected-grid control system and generation system) achieve the whole process of running simulations from the connected-grid control to the maxim wind power tracking control.In the experimental study, in the paper a complete set of 1650kW AC-excited variable speed constant frequency wind power generation experimental system is designed and built, the main circuit of the entire experimental system are composed of control cabinet composed of double PWM-type converter, two double-fed induction generator, two sets of the whole machine control cabinet, an auxiliary 90KW asynchronous motors and other equipment; on the machine control cabinet there is a communication control panel which can communicate between converter and PLC. active and reactive power decoupling control, the maxim wind power tracking control, LVRT (low-voltage through technology) , no-load and grid-control experiment were completed. the correctness of this theory is validated by the fruitful, detailed simulation and experimental results.