Research On Energy Storage System Dispatch Model Based On Peak Load Shift

In recent years, some new energy storage technologies have obtained the continuous development and application. With the decreasing cost of battery energy storage system, the energy storage system has been applied more widely and also been applied in the peak load shift. Energy storage technology has its physical characteristics and economic characteristics. The physical characteristics which are the size of the power and capacity, the relationship between the power and capacity, and response speed. The economic features which are the relationship between energy storage systems investment cost and operation and maintenance cost and its rated power and capacity, the impact of its investment cost depreciation energy storage systems for each charge and discharge power of the size. Therefore, the followind results are obtained by studying the energy storage systems scheduling model based on peak load shift:the charge-discharge power in scheduling energy storage system during various periods, achieve optimal operation scheduling of energy storage system charge and discharge. Thereby, peak load shift effects and energy storage costs and electricity costs optimization are achieved, this research is of theoretical and practical value.Firstly, this paper analysis the physical characteristics and economic characteristics of various types of energy storage technologies. The lithium battery which is low price, fast response, high charge-discharge efficiency, large power and the capacity, is suitable for peak load shift. Based on this analysis, a simplified electrical model of battery energy storage system suitable for peak load shift, and the needed economic model of considering the relevant peak load shift economy is established.Secondly, based on the perspective of improving the reliability of the micro-grid system, power and capacity of the battery energy storage system is configured. Loss of load probability and expected energy not served of micro-grid system are obtained by using stochastic production simulated. The storage system power and capacity are configured by combining equivalent load duration curve for the purpose of reducing both the reliability index.Then, the mathematical model of micro-grid peak load shift by energy storage system is established. In the model, the objective function is minimizing the standard deviation of the load, power constraints and the state of charge constraints is set based on the power and capacity of the energy storage system, and a numerical example is solved for an island micro-grid system by using interior point method. Meanwhile, the different initial state of charge of battery energy storage system impact on the optimizing load shifting effect is considered. Numerical results show that the greater the initial state of charge, peak load shift effect of optimization to get worse.Finally, based on the original mathematical optimization model, the effect of the economy on the peak load shift is considered. Economic considerations which include energy storage investment cost and operation and maintenance costs, as well as for peak load shift is affected by TOU. In order to characterize the impact of economic, storage costs and electricity costs are a function of these two types of economic objective function are joined into the single objective function of the original physical function, the single objective function becomes a multi-objective function. When solving the multi-objective optimization model, linear weighted sum method is used. A series of incremental weights of the objective function between physical and economic goals through equal steps is set. Different Pareto optimal solutions are solved by combining with specific examples. Each Pareto optimal solution expresses charge and discharge power of energy storage system scheduling plan. physical indicators which characterizated effect of peak load shift load by energy storage system are calculated:peak, valley, peak-valley difference, load standard deviation, load averages, peak slip, load factor. And electricity costs and storage costs are calculated. These indicators and cost trends with known weight coefficient are qualitatively analysised. Due to limited space of cost optimization, using battery energy storage system for micro-grid system peak load shift, load standard deviation can be significantly reduced by optimization at low costs. Thereby peak-valley difference is reduced, and peak load shift is achieved ultimately.