MPPT And Power Smoothing Control Of Direct-driven Wind Power Generation With Enery Storage

Energy crisis and environmental pollution make people pay more attention to the development and utilization of new energy. Wind energy is more and more popular with people all over the world for its abundant reserves and mature technology. However, the wind power can be random and volatile, and it has great harm to the electrical equipment or power grid, which severely limits the further promotion of wind power. Therefore, to improve the power quality of wind power generation is an important problem to be solved urgently. Coordinating and controlling the energy storage system is the most effective solution to improve the quality of wind power. Single energy storage element cannot meet the requirements of power density, energy density, response speed and so on. Thus a hybrid energy storage system consisting of two or more than two kinds of energy storage elements is proposed by some scholars to control the power of wind power. This paper mainly studied the power control strategy of the battery-ultracapacitor hybrid energy storage for the direct drive wind power generation system.Firstly, this paper studied the working principle of direct drive wind power generation system and established its equivalent mathematical model & circuit model were established. The vector control of permanent magnet synchronous generator(PMSG), which is based on rotor field orientation, is deeply studied. By using the power signal feedback method(PSF), the maximum power tracking(MPPT) technology of direct drive wind power generation system was carried out, realizing that the wind turbine has always captured the largest wind energy with wind speed changing.Secondly, the power control strategy of the hybrid energy storage was discussed emphatically. By utilizing the first order filter, the wave power caused by the change of wind speed was divided into two parts, which were low and high frequency components, and the power was compensated by the battery and the ultracapacitor respectively. As a result, the method achieved power smoothing control while fully utilized two energy storage elements. The selection of the filter transition frequency was studied, and a reasonable selection method was proposed. In addition, the limitation management of the voltage of the ultracapacitor was adopted, which was called the voltage pre-control.Finally, based on the theoretical analysis and simulation verification, the experimental prototype of direct drive wind power generation system with energy storage was built and tested. Two digital signal processors(TMS320F2812) were used to control the direct drive wind power generation system and the energy storage system. C language programs of MPPT control based PSF algorithm and power smoothing control algorithm based on first order filter were designed in detail, which were proved.