Optimal energy management of a building cooling system with thermal storage: A convex formulation

This paper addresses the optimal energy management of a cooling system, which comprises a building composed of a number of thermally conditioned zones, a chiller plant that converts the electrical energy in cooling energy, and a thermal storage unit. The electrical energy price is time-varying, and the goal is to minimize the electrical energy cost along some look-ahead time horizon while guaranteeing an appropriate level of comfort in the building. A key feature of the approach is that the temperatures in the zones are treated as control inputs together with the cooling energy exchange with the storage. This simplifies the enforcement of comfort, which can be directly imposed through appropriate constraints on the control inputs. Furthermore, a model that is easily scalable in the number of zones and convex as a function of the control inputs is derived based on energy balance equations. A convex constrained optimization program is then formulated to address the optimal energy management with reference to the forecasted operating conditions of the building. Simulation results show the efficacy of the proposed approach.