EFFECT OF FUEL GRADE ON THE OPTIMIZED UNIT LOADING IN RESPONSE TO VARIABLE ELECTRICITY DEMAND OF A FUEL OIL-FIRED POWER PLANT

An optimization method based on a dynamic linear programming tool for determining "the best load distributions" over distinct units of a fuel oil-fired power plant is presented. Two approaches are analyzed in this work. In the first approach, the objective function is based upon a minimization of the fuel consumption by the power plant. The second approach aims to minimize the total operational costs, i.e. the sum of the "internal" (or fuel) boiler costs and the "external" costs (or costs of damage done by the power plant to the environment and humans). The model used as the basis of the optimization also takes into account the changes in key operating variables as well as boiler efficiency with load variations. A 1330-MW fuel oil-fired power plant is the focus of the study. The method is applied to data from the power plant for the three climatic seasons in Thailand and two fuel options (dependent on the fuel grade). The optimum time-domain loading of the power plant units is strongly affected by the objective function, thermal cycle efficiency of the individual units and grade of fuel oil fired in the boilers. It was shown that application of the optimization method can reduce the total costs by 0.3-0.9% depending upon the seasons and fuel options.