| The global energy structure is accelerating the transformation from the traditional fossil energy system to the low-carbon energy system.The installed capacity of renewable energy represented by landscape is increasing year by year,and its inherent characteristics of randomness and intermittence are also putting greater pressure on the economic operation,safety and reliability of the power grid.As a new networked energy management structure,micro grid is not only an important place for renewable energy consumption,but also an important way to optimize equipment output and energy interaction with the main network to minimize the cost of electricity while meeting its own power load.In addition,the energy storage system with the function of storing and releasing electricity can not only instantaneously suppress the impact caused by the randomness of renewable energy generation on the supply side,but also respond in time according to the dynamic change of the load on the demand side,thus alleviating and improving the "rigid" demand of power balance to a certain extent.Therefore,this paper takes the energy storage system in the micro grid as the research and analysis object,comprehensively considers the impact of the supply side and load demand side uncertainties of renewable energy on the overall operation cost of the micro grid,and then analyzes the charging and discharging strategies of energy storage under different scenarios.Specifically,the main work of this paper is as follows.Firstly,based on the idea of "point prediction+interval estimation",this paper integrates the adaptive noise empirical mode decomposition,sample entropy,long-term and short-term memory neural network and kernel density estimation method to construct an interval prediction model suitable for the uncertainty of supply and demand,and tests the applicability and effectiveness of the model from the two levels of deterministic prediction results and interval estimation results.The results show that the model can well predict the short-term wind and solar power output and load,and its prediction accuracy is higher than the comparison model.The results also verify that compared with other models,the model constructed in this paper can achieve higher interval coverage and lower average interval width at the same confidence level.Secondly,based on the interval optimization theory,with the objective of minimizing the total cost of economic operation and environmental cost of microgrid system,and considering the uncertainty of wind and solar output and load,this paper constructs an interval multi-objective optimization model for the operation optimization strategy of energy storage system in microgrid.At the same time,considering the interval characteristics of the model parameters and the contradiction of multi-objective,the model transformation process based on fuzzy mathematics is given,which is finally transformed into solving the interval single-objective linear programming problem,and the solution idea of the model is given based on the two-stage solution method.Finally,the effectiveness of the prediction model is verified by the simulation of an example in view of the uncertainty of wind and solar output and load in the model.On this basis,in order to analyze the impact of supply-demand bilateral uncertainty on the optimization strategy of energy storage operation,this paper sets up three comparative scenarios,namely,bilateral uncertainty scenario,supply side uncertainty scenario and demand side uncertainty scenario.From the overall operation status of the system,charging and discharging status of the energy storage system,and the change of comprehensive cost,this paper compares with the proposed model considering supply-demand bilateral uncertainty.Then the optimization strategies of energy storage operation are compared and analyzed.The results show that,because the forecasting accuracy of wind and solar power is lower than that of load,the fluctuation of supply side power is greater at the same confidence level,resulting in the increase of the overall cost of microgrid and the fluctuation range of energy storage charging and discharging power.Considering the bilateral uncertainty,the overall operation of microgrid fluctuates more.But in the whole dispatching cycle,the charging and discharging capacity of energy storage system increases by 44.95%,29.22%and 58.08%respectively under the worst scenarios of wind solar output uncertainty,load uncertainty and bilateral uncertainty at 90%confidence level,which also verifies the impact of uncertainty on energy storage as well as the influence of system operation.The optimization results can further reflect the change and sensitivity of the operation characteristics of the energy storage system under the influence of external factors.The innovations of this paper are as follows:(1)integrating adaptive noise empirical mode decomposition,sample entropy,long-term and short-term memory neural network and kernel density estimation method,this paper constructs an interval forecasting model for wind and solar power output and load,which has higher interval coverage and lower average interval width,and has good applicability for dealing with uncertain forecasting problems;(2)comprehensive evaluation Considering the uncertainty of wind and solar power on the supply side and load on the demand side,this paper constructs an interval optimization model for the operation strategy of microgrid energy storage system based on interval optimization theory,and gives the model transformation and solution process based on fuzzy theory.(3)In this paper,the overall operation cost of microgrid and the operation strategy of energy storage system in uncertain environment are solved and analyzed. |
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