Operation of Cogeneration Plants with Power Purchase Facilities

This paper presents an economic dispatching scheme for a cogeneration plant with thermal needs and power purchase facilities. Part of the demanded electric power is generated locally in the plant while the rest is purchased, via a tie-line, from a neighboring utility company. The primary objective of the developed scheme was to share the load among the in-plant generating units and the tie-line such that the best economical mix is achieved while the on site process steam needs are satisified. The developed scheme is applicable to a wide class of mix generation plants. The Boise Cascade paper mill of International Falls, Minnesota, is used for a case study as a typical cogeneration installation.