Power management strategies for generator-set with energy storage for 4Q-load

Diesel generators in small electricity grids are mostly not used in a very efficient way. The reason for this is twofold. First of all the efficiency of a diesel generator is dependent on the ratio between the average power and the peak power of the generator. The smaller this ratio, the lower the efficiency. Furthermore some loads can regenerate energy. In small grids this energy is mostly not needed elsewhere and should be dissipated. A solution solving both problems mentioned above, is using an energy storage device in the system. This storage can be used for peak shaving and storing regenerated energy. This paper suggests six different power management strategies: Only Generator, Peak Power Shaving, Dynamic Solution, Max On or Off, Average Power and Only Storage. The implications of these algorithms are given for a typical case study on a crane used in the harbor. Calculations show that the Max On or Off, Average Power and Only Storage methods save the most energy. Calculation of the costs shows that adding an energy storage device lowers the cost for all methods.