Operational Flexibility Analysis of 1100 MW Supercritical Coal-Fired Power Plants during Load Cycling Transient Processes

Abstract

Operational flexibility of the coal-fired power plants must be improved so as to deal with the unpredictability of renewable energy in the future. In this study, a 1100 MW supercritical coal-fired power plant was selected, and dynamic simulation model of the unit was established via GSE software. Moreover, control model was added. Dynamic response characteristics of key thermal parameters under different power ramp rates in the region of 30%-100% THA was obtained. The cumulative standard coal consumption rate and integral absolute error were selected as the economic evaluation index of the thermal system. The results show that the maximum power ramp rate of the unit in each region during loading up is smaller than that during loading down. In the loading down process, the standard coal consumption rate of the unit firstly decreases with the reduction of output power. When the load of the unit drops to the target load, the standard coal consumption rate rises to a stabler stage. The process of loading up is the contrary. The cumulative standard coal consumption rate of coal-fired power plant is the lowest, only 275 g•(kW•h)-1 during the loading down process of 100%-75% THA. However, the cumulative standard coal consumption rate is the highest, reaching 311 g(•kW•h)-1 during the loading up process of 30%-50% THA. Due to the output power of the unit fluctuating greatly, the integral absolute error of the unit is much higher than that of other load cycling transient processes during the loading up process of 50%-75% THA and 30%-50% THA. It can be concluded that the loading up process of the unit is more difficult to control stably. This study can provide sufficient theoretical and data guidance for improving the operational flexibility of the coal-fired power plants.