Multi-layer control on DC fast charging stations equipped with distributed energy storages and connected to distribution network: Managing power and energy following events

In this paper, DC fast charging (DCFC) stations are integrated into the distribution network (DN). The designed DCFC stations are equipped with several charging devices (CDs) at different rated powers, which can charge electric vehicles (EVs) at various power levels through charging points (CPs). A central control system (CCS) is designed for each DCFC, which is applied for managing its local controllers. The CDs also use distributed energy storage (DES) alongside the DC chargers in order to increase the speed of the charging process and utilize the stored energy for improving the DN operation. The DN central controller scheme is as well designed to control the CCS of DCFCs and make positive effects on the upstream distribution grid. The CCS of DN, in addition to managing the CCS of DCFCs, is responsible for controlling the charge level of DCFCs according to four control strategies in each station including improving voltage fluctuations on the DN side, injecting reactive power from DCFCs to DN during a fault on the DN side, increasing DN resiliency by supplying critical loads in the time of upstream network outage, and supplying loads with time-varying active-reactive powers. The nonlinear simulations using MATLAB-SIMULINK demonstrate that the proposed strategies can effectively improve the performance of DN in addition to accurate control of the charging process in the EVs.

Automated summary

This paper integrates DC fast charging (DCFC) stations into the distribution network (DN) and designs DCFC stations equipped with charging devices (CDs) at different rated powers to support electric vehicles (EVs) charging. A central control system (CCS) is designed for each DCFC to manage its local controllers. Distributed energy storage (DES) is also used to increase the charging speed and improve the DN operation. The proposed strategies effectively improve the DN performance and accurately control the charging process in the EVs, as demonstrated by nonlinear simulations using MATLAB-SIMULINK.