Bi-Directional Nano Grid Design for Organizations with Plug-In Electric Vehicle Charging at Workplace

Abstract

Conventionally, the power systems are operating separately as AC or DC grids. Both systems have their advantages and disadvantages; however, if the AC loads need to be connected with the DC grid or DC loads with the AC grid, then DC-AC and AC-DC converters are required that results in conversion losses and an increase in the overall cost. Therefore, a comprehensive solution is the hybrid AC-DC grid in which DC loads relate to the DC grid and AC loads relate to the AC grid and one bi-directional converter joins both AC and DC grids and provides need-based power sharing between them. In future, it will be beneficial to operate big organizations, such as data centers, industry, and telecom exchanges under hybrid AC-DC grids because of the ever-increasing DC load demand and to avoid multiple AC-DC-AC conversion losses. Moreover, in recent times the use of Electric Vehicles (EVs) is increasing rapidly and now workplaces are required to have their own EV fast charging docking stations that adds an extra DC load demand for the organizations. Therefore, by keeping the facts in view, we proposed a hybrid AC-DC nano-grid based distributed power generation and power consumption is proposed as a suitable solution to reduce multiple conversion losses within the organizations. The AC and DC load of the Lahore's central telecom exchange is modeled for the simulations. For hybrid AC-DC nano-grid, a droop controller based bi-directional converter is designed for need-based power sharing between AC and DC nano-grids. The proposed hybrid AC-DC nano grid eliminates the excessive voltage conversion problem of telecom exchanges; provide fuel cell and battery bank-based emergency backup solution along with DC fast charging system for the EVs.