A Stochastic Robust Approach Of Optimal Energy Storage Power Considering New Energy Uncertainty

With the development of distributed generation,controllable loads,energy storage system(ESS)in distribution grid,the distributed resources(DRs)have posed a higher requirement on the operation and control of power system.It is necessary to build an active distribution network which can actively absorb the distribution generation(DG),enhance DR availability and increase the distribution infrastructure utilization so that customers are provided with power of better quality.However,the high penetration of renewable energy resources(RESs)has posed great threat onto the system stable operation.Recently,researches on ESS have attracted much attention due to its chargeable and dischargeable characteristics which can smooth the RES output.But the expensive cost and the great maintenance fees make it necessary to conduct research on the economic installment of ESSs.Based on the above background,this paper focus mainly on the following aspects:1.A robust optimal power flow considering wind power uncertaintyAn optimal power flow(OPF)model is proposed considering the probability distribution(PB)ambiguity of the wind power forecast error(WPFE).The proposed model ensures the system operation safety and economy through dispatching the thermal units under all possible WPFE distribution.The optimal solution is compared with that of the traditional chance constrained OPF model which in turn verifies the feasibility and effectiveness of the proposed model.2.Distributionally robust joint chance constrained optimal capacity installment of energy storage in power system with high penetration of wind powerThis part of work extends the method of estimating the optimal installment of ESS considering the distributional uncertainties of WPFEs.Results indicate that the method proposed ensures safety of power system operation under the worst-case WPFE distribution as well as minimizing the cost of installing ESSs through jointly dispatching scheduled output of dispatchable generation units and installed capacityof ESSs.Firstly,according to the historical data of wind power,the second-order moment of WPFE is formulated as fluctuation interval providing incompleteness of data.Afterwards,the distributionally robust joint chance constrained(DRJCC)approach is demonstrated to describe the optimal installment model of ESSs with large penetration of wind power in power system.Furthermore,s-lemma and Schur complement are adopted to eliminate the uncertainties in the proposed model so as to reformulate a deterministic linear matrix inequality problem.At last,a new method involving convex optimization.is applied to solve the problem.WPFE fluctuation interval,confidence level of DRJCC,covariance of WPFE,system structure and flexible resources are taken into consideration to evaluate their influences on the results of ESS optimal installment.3.The higher probability moment-based minimum capacity of the energy storage system in active distribution network.A method of determining the minimum ESS capacity in the active distribution network is proposed considering the randomness of the distributed load and resources.The random variable is modeled based upon its higher-order moment in probability theory.Also,an evaluation index of assessing the power supply reliability is defined.The quantitative relationship between the index and the minimum ESS capacity can be obtained by applying mathematic optimization algorithm.