Cost/comfort-oriented optimization algorithm for operation scheduling of electric water heaters under dynamic pricing

This paper presents a heuristic algorithm, which schedules the operation of electric water heaters (EWHs) under dynamic electricity pricing. The algorithm takes into account cost and comfort preferences/constraints as well as energy pricing and hot water consumption and minimizes the energy cost without significant compromise of the perceived comfort level, operating either in a cost- or comfort-oriented mode. Its performance was evaluated through simulation assuming a day-ahead real-time pricing (DA-RTP) tariff and a time-varying bound on power consumption, taking into account the user's daily hot water consumption rate. A comparison between the proposed heuristic algorithm and an optimal scheduling algorithm showed identical performance, in terms of energy cost reduction. Also, a parametric analysis studied the effect of several critical parameters (maximum water tank temperature, EWH's rated power and capacity) on the performance of the scheduling algorithm. A significant feature of the proposed algorithm is its low computational complexity, which extends its applicability to low-cost embedded controllers.