Design of Hybrid DC Mini Grid for Educational Institution: Case Study

Abstract

An education institution campus consists of several academic departments, laboratories, class rooms, seminar halls, administration office, guest house etc. The major operating electrical loads (base loads) are lighting and HVAC loads, intermittent loads are laboratory equipments etc. The fluorescent, CFL lightings are mostly used for indoor applications and sodium vapour lamp for outdoor applications. The advantages of LED in illumination technologies take the attention to switchover from other illumination devices to LED. Presently most of the LED lightings are connected in 1ɸ AC supply, AC to DC conversion is required for LED operation resulting to additional energy loss in the converter and current harmonic injection to the grid. This paper proposes the design of hybrid (solar, battery energy storage and utility) 110 V DC mini grid for lighting, HVAC and corridor lighting application. Solar is used as a prime source to power the loads in day time, energy stored in the battery is used for night time, utility power supply is used when solar and battery energy is not available. During the non-working days and holidays, power output from the solar PV is exported into the grid.