Comparison of stability regions for a line distribution network with stochastic load demands

TL;DR

This paper compares the stability regions of different power flow models in large line distribution networks with stochastic EV charging demands, revealing how stability limits scale with network size.

Contribution

It provides an explicit comparison of stability regions for Distflow and Linearized Distflow models as the number of charging stations grows large.

Findings

Stability regions decay as 1/N^2 with network size N.

Difference between models' stability regions is bounded by explicit constants.

Both models exhibit similar asymptotic stability behavior.

Abstract

We compare stability regions for different power flow models in the process of charging electric vehicles (EVs) by considering their random arrivals, their stochastic demand for energy at charging stations, and the characteristics of the electricity distribution network. We assume the distribution network is a line with charging stations located on it. We consider the Distflow and the Linearized Distflow models and we assume that EVs have an exponential charging requirement, that voltage drops on the distribution network stay under control and that the number of charging stations $N$ goes to infinity. We investigate the stability of utility-optimizing power allocations in large distribution networks for both power flow models by controlling the arrival rate of EVs to charging stations. For both power flow models, we show that to obtain stability, the maximum feasible arrival rate, i.e. stability region of vehicles is decaying as $1/N^2$, and the difference between those arrival rates is up to constants, which we compare explicitly.