# Hierarchical Distributed EV Charging Scheduling in Distribution Grids

## TL;DR

This paper introduces a hierarchical distributed EV charging scheduling method that optimizes grid loss reduction and cost efficiency using iterative consensus and ADMM techniques, validated on IEEE-13 bus system.

## Contribution

It presents a novel hierarchical distributed approach combining consensus and ADMM for scalable EV charging scheduling in distribution grids.

## Key findings

- Effective reduction in grid loss demonstrated.
- Cost savings achieved through optimal EV and BES control.
- Scalability shown with increasing EV numbers.

## Abstract

In this paper, a hierarchical distributed method consisting of two iterative procedures is proposed for optimal electric vehicle charging scheduling (EVCS) in the distribution grids. In the proposed method, the distribution system operator (DSO) aims at reducing the grid loss while satisfying the power flow constraints. This is achieved by a consensus-based iterative procedure with the EV aggregators (Aggs) located in the grid buses. The goal of aggregators, which are equipped with the battery energy storage (BES), is to reduce their electricity cost by optimal control of BES and EVs. As Aggs' optimization problem increases dimensionally by increasing the number of EVs, they solved their problem through another iterative procedure with their customers. This procedure is implementable by exploiting the mathematical properties of the problem and rewriting Aggs' optimization problem as the \textit{sharing problem}, which is solved efficiently by the alternating direction method of multipliers (ADMM). To validate the performance, the proposed method is applied to IEEE-13 bus system.