New coordinated control strategy of boiler-turbine with storage system based on the heat to power conversion characteristics for operational flexibility enhancement

High flexibility is essential for maintaining the safe and stable operation of power systems with a high-proportion of intermittent renewable energy generation. Integration of an energy storage system is an effective way to improve the flexibility of thermal power plants. In this manuscript, a new coordinated control strategy based on the load decomposition, considering the heat to power conversion characteristics of a boiler-turbine with an energy storage system, is proposed to improve the flexibility of the power plants. The core concept of the load decomposition is that the turbine load commands equals the sum of boiler and energy storage system load commands. The proposed new coordinated control strategy is examined by a case study of a boiler-turbine with energy storage system. The results show that the maximum load down and up rates are up to 7.0 % and 6.5 % Pe₀ min⁻¹, and the maximum reductions in standard coal consumption rates during load down and up are 1.4 and 1.8 g kWh⁻¹, respectively. Additionally, the round-trip energy efficiency of the turbine-boiler-storage system during load down and up is improved by decreasing the extraction steam/water ratio or increasing the load cycling rate during load up. This study provides a comprehensive guide for enhancing the operational flexibility through the coordinated operation of the boiler, turbine, and energy storage systems.