Active Distribution System Reliability Evaluation Based On Load Optimization Of User-side

With the expansion of power grid and the growing of power demand,power system peak load and peak-valley difference are also increasing rapidly,which have brought great pressure to the safe and economic operation of power system.Expending total installed capacity and line power transfer capacity will lead to larger investment and low equipment utilization.In order to relieve power supply pressure during peak period and improve the average load rate,this paper discusses the load optimization method in user-side and access the impact of optimal result on the distribution reliability.Firstly,this paper designs a load sequence probability moedel for distribution reliability evaluation.It's more suitable for distribution reliability evaluation than sequence model or peak load model,which considering the probability distribution of peak load based the daily load curve.This paper also proposes an improved sequential monte-carlo method,which can improve accuracy and stability of calculation results by simplifying distribution network and stratified smpling.On the basis,for the reason that the existing time-of-use(TO U)price models always ignore the impact of distributed generation(DG)output and the difference of customers' response characteristic,this paper designed a TOU price model to solve this problem.The model is built up by setting the load shifting as the object and considering the constraints of consumer,power network and power market.Then embed the optimized load curve into the process of reliability evaluation,and evaluate the effect of demaind side response on evaluation results.The example shows the prosed model can shift the load peak effectively,and improve the accommodation capability of DG and reliability of distribution network.Then,different control strategies of energy storage system(ESS)are disgned for the normal and fault state of distribution network,considering ESS can shift peak load and be used as backup power.An interval iterative method is proposed to sovle the charging and discharging power on the whole day when ESS is used to shift peak load.Two control strategies of ESS are used to ensure power supply for important load or all load based on the uninterrupted power supply demand of different users when a failure happens.The example shows ESS can play a role of load peak shifting,and the control strategies are reasonable and effective.In the end,the optimal allocation model of ESS is built up,which setting the maximum annual value of comprehensive income as object,considering its benefit from shifting load peak and improving distribution reliability and its cost of investment and operation maintenance.The model optimize the capacity of ESS based on the implement of TOU price,which can further improve the effict of load shifting and the reliability and economics of power system operation.