Cost-optimal model predictive scheduling of freezers

Abstract

A cost-optimal model predictive scheduling algorithm is presented that operates in a day-ahead market. The underlying optimizer is a heuristic branch and bound algorithm that finds the constrained optimal scheduling of a freezer with respect to hourly changing energy price. The method is also able to iteratively re-estimate the heat capacity of the freezer. Simulation experiments were performed on a freezer model identified from measurement data. Results show that the proposed algorithm successfully decreased the cost of operation, however the computational complexity increases when the price is growing. The proposed method can be generalized for home appliances of different kind.

Optimal scheduling of a household refrigerator using adaptive model predictive technique

“…The physical meaning and the estimated values of the parameters as reported in our previous paper [12] can be found in Table I. It is important to note that the heat capacity of the containment C a varies with the varying load of the refrigerator, while all the other parameters can be assumed to be constant.…”

“…The model predictive scheduler described in [12] serves as a starting point of the present work and its operation is summarized in what follows. The optimization algorithm behind the MPC problem to be solved in each iteration is a heuristic branch and bound binary search algorithm based on the following three rules:…”

“…The heuristic model predictive control algorithm proposed in [12] meets almost all the above control aims except for the adaptivity with respect to the changes in the interior heat capacity caused by the quantity of food occassionally put in and removed from the refrigerator. It also works if C a is unknown (i.e.…”

“…A simple dynamic model of the refrigerator was developed in [12] using first engineering principles, i.e. energy conservation for the refrigerator container (denoted by a subscript a ) and for its wall (denoted by a subscript w ).…”

“…The starting point for the current work is the development presented by [10] where MPT toolbox [11] available in Matlab has been used for the cost optimal operation of household refrigerators [12] in the constant parameter case. The optimizer algorithm behind the model predictive scheduler has been changed to an adaptive branch-and-bound binary search algorithm capable of estimating the actual load (food) of the refrigerator.…”