Optimal Sizing For Multi PV-and-Storage Microgrids In Distribution Network

Photovoltaic(PV)output power has the characteristics of intermittency and randomicity,and it brings challenges to the safe operation of the grid.The energy storage system(ESS)can effectively compensate for the shortcomings of the volatility of the PV power.Direct access to distribution network system with high PV penetration or building PV-and-storage microgrids has important significance on ensuring the safe and economic operation of the distribution network.The main work of the paper for is as follow:(1)To achieve the sizing optimization of distributed ESS in distribution network with high PV penetration,this paper puts forward a planning model,which takes into maximizing the system voltage index and minimizing the ESS's total cost during the planning period as the objective function.To solve the problem of overvoltage in distribution network with high distributed PV penetration,this paper proposes a strategy for voltage self-government in the cluster,through which it can achieve global voltage control by regulate the reactive power of PV inverters and active power of ESS,and it is also taked as the operation strategy for ESS.To solve the problem of distribution network partition,this paper puts forward a comprehensive index for network partition based on the electrical distance and regional voltage regulation capability,which is used to get the partition result of distribution network by Tabu search algorithm.The proposed algorithm has been applied to a distribution network of somewhere.(2)This paper proposes a bi-level optimization method to address the PV and ESS sizing optimization of distribution network with multi PV-and-storage microgrids: the daily cost minimization of each microgrid is conducted in the low-level optimization,through a liner programming optimization model;A PV and ESS sizing optimization scheme with minimum the total cost of multi PV-and-storage microgrids and the economic cost of distribution network during the planning period is obtained in the up-level optimization.In the up-level optimization,considering the operation constraints of the distribution network,based on the optimization results of each PV-and-storage microgrid,this paper proposes a voltage regulation strategy based on active power voltage sensitivity factor to ensure the node voltage constraints caused by PV-and-storage microgrid.In multi-objective optimization,the TOPSIS(a multi-attribute decision-making method)based on some indexes which are proposed in this paper is adopted to choose the best optimal solution from Pareto solution set.The proposed algorithm has been applied to a distribution network of somewhere in Jinzhai county of Anhui province,which shows the effectiveness of the proposed model and solution strategy.