Optimization on coordinate control strategy assisted by high-pressure extraction steam throttling to achieve flexible and efficient operation of thermal power plants

Operational flexibility of thermal power plants is urgently needed to maintain balance between supply and demand in power grids with high penetration of intermittent renewable energy generation. A new coordinate control strategy based on dynamic simulations was proposed and evaluated in this study to enhance the operational flexibility of thermal power plants. The dynamic simulation model of the control object, a double-reheat coal-fired power plant, was developed and validated. The operational flexibility of the power plant was examined using the original control strategy, and results indicated that the reheat steam is seriously overheated when the power ramp rate increases. A new coordinated control strategy assisted by high-pressure extraction steam throttling was proposed to address the issue of reheat steam overtemperature and further increase the power ramp rate. The proposed control strategy obviously improved the control performance of thermal parameters, especially the reheat steam temperature. The change magnitude of reheat steam temperature decreases by 3.0 °C. Moreover, power ramp rate increases from 1.5% to 4.5% Pe0 min⁻¹, which significantly enhances the operational flexibility. Furthermore, the proposed control strategy is compared with previous ones from the aspects of the flexibility and efficiency.