Multicriteria optimization of the investment in the auxiliary services of thermal power plants: A case study

Thermal power plants have traditionally operated at rated power as base load, but nowadays they operate at partial loads because of the new situation of the electricity market. These plants have raised their auxiliary services consumption because, in most of the cases, the auxiliaries were not designed to efficiently operate at partial loads. This paper presents a multiple criteria study about the efficiency improvement of the auxiliary services. We consider the economic investment and the net present value, as economic criteria, together with the energy saving criterion. In the multiobjective model proposed, the energy model is validated using several measures taken in a 1100 megawatts coal power plant. Besides, the multiobjective problem associated to the case study considered is solved using evolutionary multiobjective optimization and considering preference information. The results obtained conclude that a significant efficiency improvement of the auxiliary services can be achieved by means of the improvement strategies considered. Indeed, the high net present values reached indicate that the investments required by the different solutions are really profitable from the economic perspective. Therefore, investing money in the efficiency improvement of the auxiliary services represents a very profitable option for improving the operation of power plants at partial loads.