Research On Optimal Scheduling Of Energy Storage System In Microgrid

Energy storage system(ESS)is a double-flow device for energy storage and release.This device can not only improve the efficiency of renewable energy,but also benefit the energy providers in the market.ESS is essential in the microgrid,and concrete target needs should be considered with a specific scheduling strategy in the course of regulating the energy storage unit in order to realize the stable and economic operation of the system.Traditional researches on distributed ESS of the microgrid mainly adopt a centralized control method and only focus on the control by means of charging and discharging of ESS for the purpose of stability and economic efficiency.However,in theses researches the cost by the recession of the energy storage,which has different features in the short and long term,is neglected.The previous researches have some omissions,for example,the topological changes of the communication network of the microgrid or the energy storage unit exceeding the capacity limitation may cause unbalanced output of the active power.For the medium-term and long-term regulation,energy utilization is affected by seasons and the electrovalence,bringing excessive use of the stored energy.As for economic regulation,energy utilization is greatly influenced by the prediction of the renewable energy power generation,and regulation of stored energy in short time can enhance the stability of the microgrid;however,frequent regulation would accelerate the recession of stored energy.The increasing recession cost aforementioned would further increase the operation cost of the microgrid and affect the providers' earnings.In view of the above issues,the following studies are performed:1)In order to the tackle the short-term coordination control of microgrid distributed ESS which is neglected by previous researches in terms of the recession of stored energy,the cooperative control method based on a consistent incremental cost is used,a cost model of short-time recession of the store energy is established and the objective function of the cost of stored energy recession is considered;the increment of the objective function is used as an variable of the consensus algorithm,and regional data between the interaction of two adjacent energy storage unit are used.If the incremental cost becomes consistent,the output of ESS and the renewable energy would balance the power required by the load.Experiments are performed for convergence analysis,electrovalence fluctuation,changes of the network topology of microgrid,and the situations when stored energy output and capacity exceed the limitation.2)Features of photovoltaic output of the microgrid and the loading in different seasons are taken into account,and the medium-term and long-term regulation of ESS of the microgrid is explored.Particle swarm optimization is used to establish the cost model of long-term recession of ESS.The objective function of the cost is considered to perform simulation analysis of the typical day for the microgrid in every season in one year;ESS on the typical day in every season for various electrovalence is optimized,and the providers' operation costs before and after the optimization as well as the cost of stored energy recession are analyzed.3)As for the economic regulation of ESS of the microgrid,the current research was mainly base upon a scheduling strategy from the prediction of the renewable energy which has prediction errors.The optimal economic regulation in different time ranges should be considered.In view of this,a scheduling method based on the control of model prediction is put forward.On the basis of renewable energy power generation and the load prediction,the recession cost of the store energy is considered to establish the objective function;ESS is regulated by the regulation layer with a large time scale for the sake of minimum cost of the microgrid,and the optimal strategy is delivered to the regulation layer with a small-time scale which regulates the stored energy for the sake of the renewable energy power generation.Simulation experiments under different prediction accuracy,prediction ranges and electrovalence modes are performed.Three aspects including the short-term coordination control of ESS,medium-term and long-term optimal control of ESS,and the economic regulation of ESS are studied,and the simulations in various scenes has verified the validity of the method.