Reducing user discomfort in direct load control of domestic water heaters

Direct Load Control (DLC) is an effective instrument for achieving a guaranteed load curtailment. Unfortunately, if a customer considers that personal discomfort outweighs money savings after DLC shutting down of home appliances, DLC solution can be rejected. This paper proposes the way to remediate customer comfort concerns by pre-storing additional energy in electric loads before their disconnection from the grid. We take electric tank water heaters as an illustrative example of residential loads with storage. To illuminate our approach we first show how to balance electric consumption for pre-storing with user thermal discomfort for a single water heater. Then, we illustrate how the approach can be scaled-up to a multiple-boiler scenario, when ten remotely controlled boilers act next to fifty non-controlled boilers. The simulations for the latter case show that the expected user thermal discomfort can be significantly reduced at the cost of a reasonable increase of electricity demand preceding DLC event.