Optimal Design and Daily Operation of a Hybrid CHP System with Energy Storage

The study and the optimization of single devices and plants, as well as of integrated systems among producers and users, must be performed considering the possibility of energy storage and of the conversion among different forms of energy in order to reach the best overall energetic and environmental performance. Small CHP distributed plants are particularly interested in these challenges, both in stand-alone and grid-connected configurations. Many different approaches have been proposed and applied to the optimization. In this paper, the optimal design and management strategy of a CHP system composed by a PV plant, a diesel CHP engine, a reversible heat pump and a boiler is studied. The possibility of storage by means of a hot reservoir, a cold reservoir, a pack of batteries, and a pumped hydro energy storage (PHES) is investigated. By applying a model based on the Particle Swarm Optimization (PSO), the size of the different devices and the operation strategy are simultaneously optimized. The most suitable hourly-based operation profile of the devices and the best management strategy of the energy storages were performed. The minimization of the overall costs was the problem’s optimization target, while the main constrain was the fulfilment of the users’ request of electricity, heat, cooling and drinking water.