| With the rapid development of human society,people's demand for electricity is increasing.At the same time,energy shortage and environmental pollution are becoming increasingly prominent.Vigorously developing and utilizing wind energy is an effective way to solve these problems.Due to the strong volatility and randomness of wind power output,large-scale wind power integration has great impact on power quality,frequency stability and operation scheduling of electric power system.How to take effective measures to smooth the fluctuation and improve the controllability of wind power output has become an urgent problem to be solved.The rapid development of energy storage technology provides an effective solution to improve the power fluctuation of grid-connected wind power.The battery energy storage system has the characteristics of fast response and accurate tracking of power changes,regulating active wind power output and participating in system frequency control.Therefore,it is suitable for coordinated operation with large-scale wind farms to adjust wind power output,so as to reduce the fluctuation of wind power output and negative impact on the power grid,and improve the power quality and frequency stability of the system.Firstly,the fluctuation characteristics of wind power and the influence of large-scale wind power access on the frequency stability of power grid are analyzed,the operation performance and equivalent circuit model of battery energy storage system are mainly introduced,and the principle of using energy storage system to improve power fluctuation of grid-connected wind power is expounded.Then,improving the characteristics of wind power integration and the frequency stability of power grid as the goal,Pre-control strategy based on short-term wind power forecasting is adopted to control the output of windstorage combined system,and a wind-storage combined system is simulated as an example.The results show that this method can effectively smooth the fluctuation of wind farm gridconnected power,reduce the frequency modulation pressure brought by wind power integration,and improve the grid's acceptance of wind power.Finally,considering the restrictive relationship between the cost of battery energy storage system and the benefit of wind farm,the penalty cost of wind power fluctuation exceeding the limit is introduced according to the related grid-connected standards of wind power,an optimization model of energy storage capacity is established with the maximum net income of wind-storage combined system as the objective function is established,and sensitivity analysis of penalty coefficient is carried out.The results show that reasonable penalty coefficient and appropriate capacity of battery energy storage system can improve the economic benefits of wind farms and help to achieve large-scale wind power grid-connected. |
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