Short-term scheduling of industrial cogeneration systems for annual revenue maximisation

This paper addresses the optimisation of short-term hourly scheduling (one week ahead) of (CHPs) cogeneration plants inside large industrial sites. The heat demand in these sites is very high and is crucial for industrial processes.This optimisation aims to find the CHP operation points that maximise the profits from the sale of heat and electricity. The electricity price must be forecasted because it depends on the day-ahead market outcomes, whereas the heat price depends on the long-term contracts between the utility owners and the industrial site counterparts.These operation points must comply with technical, legislative and economic constraints. In particular, the cogeneration indices that are imposed by current Italian law must be met for a plant to receive important benefits, such as green certificate purchase exemptions and priority dispatching.A Matlab application has been developed for a generic typical configuration of a CHP and consists of both combined cycle gas turbines and backpressure units. The optimisation procedure has been applied to a case study consisting of two combined cycle gas turbines and two backpressure units. The relationships that allow us to evaluate the unit net heat rate have been calculated using experimental measurements and manufacturer data. It is worth noting that the application of the optimisation method ensures that the cogeneration indices are met and allows the plant to increase its yearly profit by approximately 6% in comparison with a typical CHP management system that is based on a prefixed distribution of heat demand for each unit.