Optimal scheduling of gas and electricity consumption in a smart home with a hybrid gas boiler and electric heating system

Abstract

Space and water heating are two major components of household energy consumption, and a number of work has been done to combine multiple residential heating technologies to develop hybrid heating solutions that are more flexible, efficient and economical. This paper studied and modelled a smart home with a novel hybrid heating system, which consists of a wall-hung gas boiler (for both space and water heating) that is connected to a water tank with an auxiliary electric resistance heater (for water heating), and auxiliary split air conditioners (for space heating). A multi-objective optimization was further formulated to optimally schedule the gas and electricity consumption of a smart home equipped with the hybrid heating system as well as an onsite photovoltaic (PV) system, a battery energy storage system, an electric vehicle and various types of flexile loads. Two objectives, i.e. the minimization of operating energy cost (including both electricity and gas payment) and the maximization of thermal comfort, were considered. The optimization problem was finally transformed to a single objective mixed integer linear programming problem that can be solved by existing optimization solvers. Simulation results verified the operational performance of the studied hybrid heating system and the effectiveness of the proposed scheduling method. Sensitivity analysis was conducted considering various levels of electricity/gas prices, onsite PV capacity, battery capacity and outdoor air temperature, and it shows that in all the scenarios the operating energy cost of the smart home with the hybrid heating system was always lower than that with the pure electricity or pure gas heating systems. The performance under various uncertainties and the benefits of adopting model predictive control were also demonstrated. It is noted that this paper only focuses on the optimal scheduling and operation costs of the hybrid heating system. Optimal configuration and sizing of the heating system with the initial investment (i.e. capital expenditures) considered are identified as research directions in the future.