Rule-Based Energy Management System

Real time pricing of electricity and rising fossil fuel costs are causing renewed interest in energy management systems (EMS). This paper describes a rule-based EMS which has been implemented at several large industrial powerhouses. It is a PC-based supervisory system which is interfaced to a DCS. The EMS includes boiler allocation, turbine load allocation, bark optimization, real-time pricing (RTP) tie-line control and coordinated header pressure control. It optimizes the powerhouse operations to meet the steam and electrical requirements of the mill at minimum cost subject to all of the operating constraints imposed on the generation equipment. \nSteady state optimization methods, such as linear and non-linear programming, are not suited for online optimization of powerhouse operations since the process is rarely at steady state. Instead, the optimization strategy is reduced to a fairly small number of fuzzy rules. It has proven to be capable of optimizing the powerhouse operations while keeping the powerhouse within a safe operating envelope. \nOne of the unique features of the EMS is the safe operating envelope. It is defined by setting up a prioritized list of process, equipment and environmental constraints.