PEV Charging Optimization Considering a Dynamic Rating of Primary Distribution Transformers

This article proposes a methodology for the coordination of Plug-in Electric Vehicle (PEV) battery charging, which allows limiting the Hot Spot Temperature (HST) of the Primary Distribution Transformer (PDT) to a constant value. For this, a dynamic rating of the PDT has been incorporated as a constraint in the formulation of the PEV coordinated charging optimization problem. The Susa thermal model has been adapted to calculate the PDT dynamic rating. In addition, the methodology is solved iteratively for different values of the HST up to its optimal limit, which allows minimizing the loss of daily life of the PDT, and the corresponding PEV charging profiles are obtained. Finally, the proposed methodology is applied to a case study, which consists of a system with 32 aggregators. In the results of the case study, it can be observed that the methodology effectively limits the HST during the daily operation of the system while the energy requirements of PEV are satisfied.

I. Introduction

Nowadays, there is a trend to implement electric mobility technology in transportation systems. The massive connection of Plug-in Electric Vehicles (PEVs) to the distribution networks will have a significant impact in its assets if the charging of the PEV batteries is not properly coordinated. In particular, Primary Distribution Transformers (PDT) have high acquisition, transportation and installation costs, and they are considered critical assets for the operation of such networks.