A novel centralized charging station planning strategy considering urban power network structure strength

• Compared with the charging demand prediction under V2G mode, the battery swapping demand analysis method under B2G charging technology applied in the paper can achieve a more accurate one through the separation between the randomness of EVs’ arriving and real-time charging capacity of centralize charging station. It is conductive to enhance grid stability and helps to arrange battery charging and discharging schedule more flexibly.
• Power supply moment index based on the actual power supply path group of each source-load pair and real-time power flow change on them represents the time-space characteristic of load shifting well and application of the relevant balance index is quite useful to understand the fluctuations that occur in the grid under high penetration of electric vehicles and charging stations.
• The novelty of proposed model is combined observation not just of the EV charging requirements but also of grid strength and reliability. Better network structure with reasonable station planning is capable of forming quick interregional power support, which is also conducive to defense unexpected fault for the improvement of the grid operation stabilization.
• Usage of the power flow tracing method contributes to analyze the power flow of the network thoroughly and is beneficial to discover the irrationality of the replacing all the power supply paths with a single shortest electric distance path in calculation.

Considering detrimental impact on grid by sizeable and unpredictable electric vehicles (EVs) loads, establishing centralized charging stations through swapping batteries can be the future competitive development orientations in EV industry. Optimal centralized charging station planning is not only pervasive enough to meet the requirement of EV charging, but also has the potential to improve the rationality of power grid structure as a distributed power station. In this paper, a novel centralized charging station strategy considering urban power network structure strength is proposed. Based on the analysis of time-space characteristic of load shifting in normal urban life, power supply moment balance index is defined to represent fluctuation of supply capability between peak and valley under certain structure. Meanwhile, the investment of charging stations and network loss are considered as part of objective function with moment balance index, aiming at improving urban power network structure with minimal economic cost. Case study on IEEE 123-bus test distribution system illustrates the validity of the strategy proposed.