THE CONTRIBUTION OF AUTOMATIC CONTROL TO ENERGY SAVING

The present work shows the contribution of optimal control to energy saving for two different dynamical systems. An optimal control consists in determining the manipulable inputs variables which transfer the system from an initial to a final state satisfying the system dynamics, and optimizing a certain quality criterion related to the system performance. These optimal control problems are solved by a systematic, general usage and easy Computer Aided Optimization procedure, with which the originally dynamic optimization problem is transformed to an easier static parametric optimization task. The evolution of the control inputs with respect to a suitable independent variable is expressed by adequate system of analytic functions. The function coefficients are then iterated by a search algorithm to values that optimize the objective function. The technique is applied to two energy systems. The first is a Domestic Hot Water for which it is required to maximize the collected energy. The second is a space heating system for which it is required to minimize the auxiliary energy cost and a discomfort index. For the two systems substantial energy gain is realized over the ON-OFF classical controller. The gain increases as the constant value of the ON-OFF controller is far from the optimum. A sensitivity analysis is done to calculate the variations of the optimal control to variations of the system parameter with respect to nominal conditions. This can be used to simplify the implementations of the optimal control.