Abstract: The 300-MW coal-fired unit plant in a cogeneration power plant is taken as an example to show the components of a unit plant. The workflow and main monitoring/control parameters of heat supply networks are also introduced. By analyzing the inaccuracy in heating steam flow measuring in heat load logic and its impact on the coordinated control system, an updated scheme on heat load logic calculation is proposed, including the heat load changing rate and its upper and lower limits. The new logic works well and the overall performance of the unit plant keeps stable after the heat supply network being put into operation. The security and economics of the unit plant get improved.

Key words: heat supply network, heat load, power unit plant, AGC, coordinated control, DCS