Ultra-Capacitor And Battery Based Hybrid Energy Storage System Control Strategy For AC Micrco-grids In Isolated Mode

Future power generation will be more distributed than the traditional centralized system,which demands more distributed generation(DG)and renewable energy sources involvement.This involvement will result in a more sophisticated power network that needs an efficient and reliable power distribution and management system.DGs' also have introduced damaging effects on the power efficiency and quality of the main grid.A typical low-voltage micro-grid comprises of distributed generation units,renewable power,smart energy storage,residential and small-scale commercial loads and energy management system.Micro-grid normally can be operated in two modes i.e.islanded mode(without main grid)and grid connected mode.This type of low voltage micro-grids are mostly employed in the remote areas where the main utility grid is unable to reach or as a backup system in case of main grid failure.These types of grids are also relying upon the renewable energy and energy storage system strongly.Because of the intermittent nature of these energy sources and lack of utility grid energy management is very critical in such remote micro-grid.And traditional ways of storage are not optimal and demands further investigation and improvements.To solve this problem this work focuses on operational system strategy and the corresponding energy management method of a renewable source-based AC micro-grid backed up by battery storage and diesel generator working under islanded mode.Energy storage like battery bank plays an important role in energy management for load shifting and smoothing varying power.But,the battery storage system cannot be used in bulk because of their high price,maintenance and transportation issues for smoothing power disturbance ripples.To resolve this issue a hybrid energy storage(HES)scheme that utilizes ultra-capacitor and battery as a combination is proposed.This HES system will be responsible for shifting the loads and smoothing power.