A New Boiler-turbine-heating Coordinated Control Strategy to Improve the Operating Flexibility of CHP Units.

The operating flexibility of the power units is getting increasing attention from power systems especially those with large-scale fluctuating renewable energies. However, the combined heat and power (CHP) units are getting a bottleneck because their electricity productions are restricted by heat productions. This study aims to develop an electric-heat coordinated control strategy to make the CHP units more flexible. First of all, the dynamic model for a 300 MW CHP unit is set up, and its linear state-space description is obtained. A control strategy based on linear quadratic regulator (LQR) is then developed to satisfy different heat-power demands in various operating conditions. The control weights Q and R are optimized by particle swarm optimization. Moreover, the improved coordinated control strategy based on precise energy balance is put forward to increase the CHP power ramp rate considering electricity priority strategy and recovery control of the heat source. Finally, the simulation results show that the improved strategy is suitable for various CHP operating scenarios, and the case for electricity priority and heat recovery control significantly improves the unit power rate on the premise of stable heat supply. This work provides a reliable and flexible control mode for CHP units, which can support the power system stability and renewable energy integration. [ABSTRACT FROM AUTHOR]