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Combined heat and power control considering thermal inertia of district heating network for flexible electric power regulation

Wang, Wei, Jing, Sitong, Sun, Yang, Liu, Jizhen, Niu, Yuguang, Zeng, Deliang, Cui, Can
Energy 2019 v.169 pp. 988-999
dynamic models, electric power, fuels, heat, wind power
The capability to perform rapid load changes is an important issue due to its considerable support on power system stability, and its improvement is increasingly becoming urgent due to large-scale integration of fluctuant wind energies. An optimized control strategy for improving the load-following capability of combined heat and power (CHP) units is therefore developed. The strategy aims to borrow the heat extraction output to perform fast load changes given that its influence in tens of minutes on heat consumers is slight owing to the large inertia of district heating networks (DHNs). The static and dynamic models of heat–power conversion are set up. Dual control strategy is adopted to combine heat source regulation (HSR) and traditional boiler–turbine coordinated control strategy, among which HSR is taken as the primary control of power load for rapid load response and fuel control as secondary control for the final load accuracy. Finally, field tests on a 330 MW CHP unit reveal that the maximum allowable ramp rate can be raised to 4% of rated power per minute and meanwhile it almost takes no impact on heat consumers.