Study On Excitation Control Strategy Of Variable Speed Constant Frequency Doubly-fed Wind Power Generation

Because the conventional energies are limited and have pollution to the environment, more and more attention has been paid to the utilization of renewable energies, specially the wind power. Wind power generation is the most rapidly growing technology for renewable power generation in recent years.The variable speed constant frequency (VSCF) doubly-fed wind power is widely applied in large capacity interconnected running wind-electricity unit. The core technology of VSCF doubly-fed wind power generating system is excitation control technology based on power electronics and computer control technology. And the important study is excitation control strategy technology of doubly-fed generator. The theoretical, simulation and experimental study are done for VSCF doubly-fed generation in this paper.Firstly on the basis of analysis of doubly-fed generator basic theory, the stator field orientation vector control is employed, so the mathematic models of power factor angle, active power and reactive power of doubly-fed generator are established in the synchronous rotating reference frame (dq0). Therefore these build the basis of the design of control system and experimental study.Then because the output power mathematic model of doubly-fed generator is a multiple function of machine parameters, control parameters and operating situations, it is very difficult to analyze it with conventional methods. However, power factor is one of the most easily measured parameters in the three mathematic models of power factor, active power and reactive power of doubly-fed generator. Power factor not only reflects the portion of active power and reactive power, but also reflects the excitation degree of rotor voltage. Therefore, the impact of different rotor exciting parameters on stator power factor of doubly-fed generator is analyzed, and on the basis of this, excitation control model of doubly-fed generator is established based on stator power factor. Moreover, the characteristics of power factor and rotor excitation voltage of doubly-fed generator are carded out by certain simulation study. And simulation experimental system of doubly-fed generator based on the core of 87C196MC is designed. Some experiments are carded. Simulation and experimental results indicate that the established excitation control strategy model of VSCF doubly-fed generator based on stator power factor is basically fight and feasible, which conduces to the study of excitation control strategy and the design of control system of VSCF doubly-fed generator system.