Research On The ESS Configuration And The Day-ahead Generation Schedule In Wind Power Plants

As the demand for energy from human production and living increases,traditional energy cannot support the survival and development of society alone.Accelerating the transformation of energy utilization methods and optimizing the energy structure are the preferred strategies for dealing with energy shortages and solving environmental pollution problems.As a mature technology and emerging industry with the most commercial development prospects,wind power has attracted the attention of many countries and regions.However,because of its small energy density,intermittent,randomness,and instability,large-scale wind power integration will affect the stability of local grid operation.Because of dynamic energy absorption and timely release,energy storage system can effectively compensate for the disadvantages of wind power and improve capability of wind power integration.In current widely used energy storage,hybrid energy storage system consisting of electrochemical energy storage and super capacitor energy storage can take full advantage of energy-type storage system and power-type storage system,and is very suitable for wind farm.However,the configuration problem for energy storage cannot be ignored.Too large capacity configuration leads to high costs and economic waste;capacity allocation is too small,smoothing wind power fluctuations is not easy to be completed.In addition,in the wind farm where energy storage has been configured,it is also an important issue how to make energy storage participate in the operation of wind farm economically and reasonably.The key to the joint operation of wind and energy storage system is to allocate reasonable energy storage capacity and to reduce the negative impact through proper operation strategies.Against the background of this research,this paper uses a hybrid energy storage system(HESS)to mitigate wind power fluctuation for the sake of wind power participation in power system dispatching,and selects an appropriate frequency division strategy to configure a reasonable-capacity energy storage system;in the optimization of the day-ahead planning strategy of the wind farm output,a day-ahead income model for wind farm with dynamic scenario is established under the market mechanism of auxiliary services and the participation of energy storage system.In the condition of optimal economics,the planning of the wind farm output was determined.The main work of this paper is as follows:(1)Discuss the influencing factors of the battery life,summarize the experience-based battery life prediction methods and establish the charge-discharge and operating life calculation models of battery and super capacitor,which lay a foundation for the subsequent optimization calculation of the energy storage system capacity for wind farm.(2)For the problem of mitigating the wind power fluctuation using HESS,the power fluctuations are divided according to frequency division processing,which is based on the wavelet packet decomposition method and in consideration of the frequency characteristics in the island grid.The component of high frequency is absorbed by the self-consumption ability of the power grid.In addition,the components of intermediate and low frequency are power instructions of HESS.An optimization model of HESS capacity is constructed in order to realize the minimization of the wind farm annual cost.(3)After the introduction of wind power dynamic scenario generation,the transformation between the actual output variable of the wind farm and the standard normal random variable is implemented using the inverse transformation,and according to the mutual information value between different times,the scenario whose correlation characteristic is most consistent with the historical data is judged.Then the stochastic optimization model of wind farm dispatch scheduling is modeled to maximize the expected revenue from selling the energy in the energy market for different possible future scenarios of generation output,and consider the cost of auxiliary services and the related constraints of energy storage system.The simulation results verify that the proposed strategy is more economical than the traditional strategy.