###### Abstract  
Low-CO\({}_{2}\)-emission wind generation can alleviate the world energy crisis, but intermittent wind generation influences the reliability of power systems. Energy storage might smooth the wind power fluctuations and effectively improve system reliability. The contribution of energy storage to system reliability cannot be comprehensively assessed by the installed capacity of energy storage. The primary goal of this paper is to investigate the impact of the installed location and capacity of energy storage on power system reliability. Based on a bi-level programming approach, this paper presents a bi-level energy storage programming configuration model for energy storage capacity and location configuration. For upper-level optimization, a depth search method is utilized to obtain the optimal installed location of energy storage. For the lower-level optimization, the optimal capacity of energy storage is solved to meet the system reliability requirements. The influence of the contribution of energy storage location to system reliability is analyzed. The proposed model and method are demonstrated using the RBTS-Bus6 System and Nanao (NA) island distribution system in China. The results show the effectiveness and practicability of the proposed model and method. location configuration; energy storage system; optimal allocation; bi-level programming; reliability +
Footnote †: journal: Applied  
capacity of energy storage is considered based on certain related factors in the power system, including the changes in wind power [3; 14], the cost fluctuation of renewable energy [4], the spatial-temporal model of wind power [5] and other renewable energy networks [2; 7]. The optimization objective of the existing studies can be classified as follows: avoid wind curtailment [15], minimize operational cost and investment [16; 17; 18; 19], minimize power rating [20], minimize the overall system cost [21], minimize electricity cost [22], avoid voltage violation [23] and improve reliability [24; 25; 26; 27]. The optimization allocation size and location of energy storage is used to prevent load curtailment and minimize operational cost [11; 12]. The optimal size and location of energy storage can also maximize wind power utilization [9]. The methods for solving these optimization problems include linear programing [21; 23], second-order cone programming [19], exhaustive searches [13; 20], genetic algorithms [9], particle swarm optimization [10; 11], artificial bee colonies [17] and bat algorithms [18]. Relatively few studies have been conducted on the optimal configuration of the siting and size of energy storage or on which optimization objective regarding the installed location of energy storage is the most considered investment: operational costs or losses [8]. Moreover, in the existing studies, the energy storage location is always considered the constraint on the power system operation cost in the optimization [10; 11; 12]. The existing studies do not consider the energy storage system as an independent influencing factor for the system reliability, and they have failed to properly consider the effects of the energy storage location on power system reliability. A reasonable allocation scheme is established for the energy storage in a distribution network based on the required system reliability. It is necessary to separately evaluate the influence of energy storage system on reliability in power system planning. Different installation locations should yield different contributions of an energy storage system to the power system benefits [13]. An energy storage system will not be fully able to improve reliability at an improper installation point. Moreover, the positive influence of the energy storage system would be magnified with increasing wind power penetration. For power system planners, the installed capacity and location of energy storage are not easy to change once determined.