Research On Application Of Hybrid Energy Storage In Wind Farm

The advancement and utilization of renewable energy has opened the door for fixing the ongoing world energy crisis and environmental pollution.Wind power as an environmentally friendly renewable energy has been widely used. However, because of the strong randomness, intermittent and volatility, the large-scale wind power connected to the grid can bring adverse effect to the power quality of the power grid. With fast power exchange capacity and advantages of multi-types energy storage medium, hybrid energy storage system can smooth wind power fluctuations effectively. Therefore, this paper carries out the following research work:Firstly, the characteristics as well as the modeling of lithium battery and super capacitor are studied. Based on the analysis of the characteristics the existing models, the PNGV model is selected and a simple RC series model is used to simulate the super capacitor. The simulation results demonstrate the validity of the established models. As the interface of energy exchange between the energy storage and the wind farm, the mathematical model of bidirectional DC/AC converter is well studied.Secondly, this paper puts proposes a new kind of real-time discrete wavelet transform frequency division method to allocate the fluctuation power between the hybrid energy storage system. With the typical historical power data of the wind farm as the research object, we use super capacitor to suppress short-term wind power fluctuations and lithium battery to smooth longer-term power fluctuations based on the distribution principle of wind power fluctuations frequency’ value. The simulation results show the method can not only smooth wind power fluctuations effectively, but also reduces the capacity of hybrid energy storage system.Finally, this paper puts forward a control method of hybrid energy storage system based on the combination of wavelet decomposition and MPC predictive control. Compared with the traditional inertial filter PID control method, the proposed method in this paper can effectively stabilize the fluctuations in wind power and improve the control quality of the system, which has a certain practical engineering value.