Study On Control System Of Variable Speed Constant Frequency Double-Fed Generator

With the lack of general energy source,electric power and the worsening of power supply circumstance problems increasingly,it is provided with very important meanings to partially solve energy lack by using renewable energy source such as wind energy as the one of the most important clear substituted energy source in the future. Comparison with the general wind energy generation system,because of equipped transducer of VSCF doubly fed wind energy generation system located at rotor loop,it possesses the characteristics of small cubage,light weight and low cost,which only deals with slip power in double direction. VSCF AC excitation doubly fed wind energy generation system and its control technology is studied in this paper.Firstly, according to the basic principle of electrical machine, the double-fed machine's mathematical model under MT coordinate system is deduced, stator flux oriented vector control strategy as well as relational expression between stator current and rotor current are also investigated. All the researches provided theoretic base to carry out more research for double-fed control strategy.Secondly, the doubly fed generator is controlled by stator-flux oriented vector control strategy. When M axis is attached to the stator flux, the active power and reactive power can be controlled respectively. Mathematics model of wind turbine is established,and grid-connected doubly fed generation system by using back-to-back voltage-source converter with wind turbine model is mainly studied. At the same time,to realize independent control of system active power,reactive power and rotor speed by adopting maximum wind energy capture control is pointed out. It is to simulate the grid-connected doubly fed generation system, and the results of the simulation conclude that the stator-flux oriented vector control strategy is feasible.Last, mathematics model of doubly fed generator no-load grid-connection system is established,and indirect-field-oriented control scheme is studied. The experiment result concludes that the control strategy of doubly fed generator on-load system is feasible.