Research On The High-performance Control Technology Of Double-fed Wind Power Generation System

In recent years, when the energy issue had became a common problem faced by allaround the world, wind resources as a renewable clean energy is highly valued. Energy issuespromote the development of distributed generation. Wind power as an important part ofdistributed generation is playing an irreplaceable role. Especially the Double Fed InductionGenerator(DFIG) which has the characteristics of active power and reactive powerindependently decoupled, small capacity converter, low control costs and so on, and dominatethe wind power generation market. Therefore the research on improving the efficient of DFIGsystem control strategies has been became more critical. However, the entire system is verysensitive to grid fault as the capacity of DFIG converter smaller. With the increase of theinstalled capacity of wind farms, the impact of wind power systems for large power grid isalso growing.Aiming at the problem of DFIG system control, this paper researched an improvedstrategy on the basis of coordinated control of power, and an efficient DFIG convertercontroller is designed according to this strategy. The controller has a dual-CPU architecture:DSP and FPGA, and communicate with host PC through Ethernet. And then, theMatlab/Simulink model of wind power system is built based on the analyzing automaticmodel of generator. Furthermore, the effectiveness of this control strategy is verified by thissimulating. And ultimately, the converter controller is developed and applied in10kW DFIGsystem, the experiment result shows that the controller can reduce grid-connect shockeffectively, improve the dynamic response performance and gird-connection power quality.Aiming at the problem of the DFIG system which is sensitive to the power grid fault andits small converter capacity, an improved FRT circuit topology is proposed on the basis ofactive crowbar and chopper and based on the stator current feedback control strategy.According to this structure and strategy, the Matlab/Simulink model of DFIG system and FRTwere built. Furthermore, the effect of the DFIG system and the grid were studied by thissimulating in the condition of three-phase symmetrical or asymmetrical and voltage dips orpump up. Besides, the effectiveness of this circuit topology and strategy is verified. Theexperimental results show that the program not only can complete LVRT but can achieveHVRT effectively, accordingly the grid connection is maintained when grid breakdown.