Research On Control Strategy Of Stand-alone DFIG-based Wind Power System With Hybrid Energy Storage

With the world's energy security,ecological environment,climate change and other issues increasingly attention,renewable new energy technology has become the focus of attention.Wind energy due to the huge amount of goods,widely distributed,more mature technology is becoming an important part of new energy.The global cumulative installed wind capacity has grown rapidly in this year.Because of the intermittence of wind power,the output power can fluctuates and affects the quality of power supply.Therefore,the energy storage device with energy buffering can be added to the standalone wind power system,which absorbs the excess power or releases the insufficient power of the load,improving the reliability and economy of stand-alone wind power system operation.In this paper,the control strategy of standalone double-fed induction generation(DFIG)wind power system and the control strategy of stand-alone DFIG wind power system with energy storage device is designed mainly on DFIG and energy storage device.Firstly,the mathematical model and control strategy of stand-alone DFIG-based wind power system are studied.Based on the mathematical model of three-phase rotating coordinate system of DFIG and the double-PWM converter,the vector control of the indirect flux linkage strategy and the direct voltage strategy is established based on the stator flux orientation for the rotor-side converter(RSC),to control the three-phase sinusoidal voltage with constant amplitude and frequency.Based on the stator voltage orientation,the vector control of "DC voltage outer ring + current inner ring" double-closed-loop is established for the stator-side converter(SSC),to keep the DC bus voltage of the double PWM converter constant.Secondly,the structure,energy distribution scheme and control strategy of stand-alone DFIG system with hybrid energy storage device are studied.The bidirectional DC / DC converter is used to connect the battery and the super capacitor to the DC bus.According to the characteristics of the energy storage,the energy distribution scheme of the wind power is designed.Based on the principle that the battery is used to absorb excess energy or to release the insufficient energy,the super capacitor is used to alleviate the impact power of the wind energy on the load,the "power outer ring + current inner ring " double closed-loop control of battery is designed to achieve the maximum power.The “DC voltage outer ring + current inner ring” double closed-loop control of super capacitor is designed,to absorb high-frequency power,and with the stator side converter control DC bus voltage.Finally,the simulation model the stand-alone DFIG-based wind power system and the simulation model of standalone DFIG-based wind power system with hybrid energy storage device are built by Matlab/Simulik simulation platform,to simulate and to verify the control strategy of converter and the hybrid energy storage...