An Online Control Algorithm for Application of a Hybrid ESS to a Wind-Diesel System

Energy storage systems (ESSs) can be applied to mitigate some of the negative impacts associated with a variable power generation source such as wind energy. The control of ESS power must be accomplished over numerous time frames to meet system objectives and respect ESS capacity constraints. This paper proposes a two-level ESS control structure for use with a wind-diesel system, which is suitable for online implementation. The control is developed to coordinate power delivered from the two ESS levels in order to minimize diesel fuel consumption and limit up/down rates of the diesel plant. Different control modes are evaluated by simulation, and a subset of the results are validated using a hardware-in-the-loop representation. The controller that combines all three functionalities-minimizing dump load, limiting intrahour diesel ramp rates, and maximizing ESS utilization-demonstrates superior performance as measured by defined metrics and is proven to work online.