I. Introduction
The problem of operation planning of cogeneration units or plants is a complex issue that might be approached from different angles. Regarding time aspects the planning horizon is usually limited as scheduling consists in the best use of already available resources, both regarding generation and distribution assets, and it stretches between one year and few hours before the delivery period. Regarding locational aspects, the current research deals primarily with minimization of the cost of operation and/or maintenance of a single unit or a single plant [1]–[3] with detailed modelling of the thermal part and other technical constraints [4], [5]. Regarding network management, the on-going research activities address problems with integration and scheduling of cogeneration plants in electrical networks including smart grids [6], [7]. Regarding regulatory background and economics, the optimisation problem is usually driven by the total cost of units or plant operation [8], [9], by requirements related to balancing renewables, by environmental issues [3], [10], [11].