An intuitive definition of demand flexibility in direct load control

Two control approaches: direct and indirect control of demand side energy management in a smart grid are studied. Indirect control of energy demands is based on economic incentives. In this approach, consumers will shift their energy consumption with the benefit of a cut down in the electricity bill and in the cost of being flexible in terms of accepting a wider comfort zone. The other approach is to directly command a power signal to end-user loads provided that the electricity provider company is already aware of the consumer's flexibility degree. We have framed a measure of the flexibility in terms of the amount of energy that can be shifted without sacrificing comfort. A specific case study i.e. a residential building equipped with an electric floor heating system is used for demonstration of simulation results. Finally, we proposed a control method to serve both direct and indirect load shifting schemes. Simulation results show a sub-optimal result with the combination approach compared to the optimal solution with the indirect approach.