Abstract:

Objectives With the rapid increase in the installed capacity of renewable energy generation, the requirements for the operational flexibility of coal-fired power units are becoming increasingly stringent. In this context, the control of key thermal parameters of the units becomes more challenging, and the system energy efficiency decreases during transient load change processes. Therefore, it is necessary to develop a multi-parameter coordinated control strategy to balance load change rates with energy efficiency levels. Methods Based on the GSE simulation platform, this study constructs and validates a dynamic model of a 350 MW supercritical coal-fired power unit. Additionally, a boiler system heat storage model incorporating the heat storage of the working fluid and pipeline metal is established. On the basis of adopting high-pressure heater extraction steam throttling, an optimized control strategy is proposed that takes into account the change patterns of internal heat storage within the boiler system. Results During the load increase from 30% to 50% turbine heat acceptance (THA), high-pressure heater extraction steam throttling increases the maximum load increase rate of the unit from 1.5%P_e/min (where P_e represents the rated load) to 2.5%P_e/min. However, the average standard coal consumption rate during the transient process reaches 314.81 g⋅(kW⋅h)^-1. Under the premise of meeting the power standards, the optimized control strategy achieves an average coal savings of 0.67 g⋅(kW⋅h)^-1 during the transient process. Conclusions The optimized control strategy can not only significantly increase the load increase rate but also efficiently improve the system energy efficiency, providing strong support for the efficient and stable operation of coal-fired power units.

Key words: coal-fired power generation, coal-fired boiler, deep peak shaving, low load, ultra-supercritical unit, energy consumption analysis, boiler heat storage, transient load change process