Comparison Between Centralized and Decentralized Storage Energy Management for Direct Wave Energy Converter Farm

This paper compares the sizing of distributed energy storage systems (ESS) with two control types in order to smooth a direct wave energy converter farm production, namely a centralized one that deals with the point of common coupling (PCC) power with aggregated information and a decentralized one that deals with each unit with only local information. The main objective is to compare the two controls on the basis of their life cycle cost. The ESS is necessary for grid integration in the case considered here due to the flicker constraint. The co-optimization strategies for both the sizing and the management of an ESS are based on a rule-based energy management and a sequential approach to deal with the power quality constraint. This management strategy has been optimized for each size in order to reduce aging speed while respecting the flicker criterion. The final design is expected to minimize total system cost. The centralized control clearly allowed smaller capacity. However, it may lead to an increase in cables losses compared with the decentralized case, although it is expected to be negligible under the conditions considered in this paper. The confirmation of this hypothesis will be the objective of future work.