Industrial implementation of economic dispatch for co-generation systems

The objective of this paper is to address an industrially implemented economic dispatch (ED) function for cogeneration units, i.e. generating units with output in the form of both electric power and heat. The heat produced by the cogeneration power plants is used for desalination of sea water and the variation in demand for electricity and heat are therefore not correlated. This implies that an optimal loading of each generator can only be achieved if both of these two requirements are considered by the optimization model. The ED module solves the optimal dispatch problem considering both the electric load as well as the heat requirements provides the generation control thereby providing the operator important real-time decision support. Three different types of cogeneration plants are considered. The first plant configuration type consists of a gas turbine and a heat recovery steam generator that extracts heat from the gas turbine exhaust to produce steam. The second configuration type consists of a conventional combustion boiler and a steam turbine. The third considered plant configuration is what is also called combined cycle plants, i.e. a gas turbine with a heat recovery steam generator that produce steam for the operation of a steam turbine.