[Objective] In order to tap the energy storage potential of the turbine -side thermal system and develop efficient auxiliary frequency modulation technology, the static characteristics of load response capability of a subcritical 300 MW thermal power unit under different regenerative heater extraction adjustment modes are analyzed. 

[Methods] The static simulation model of the unit was bui lt based on the EBSILON platform, and the accuracy of the model was verified. Under the four working conditions of 75%THA, 50%THA, 40%THA and 30%THA, the variable load capacity and static characteristics of various adjustment schemes in the middle and low 2 load sections are compared and analyzed by adjusting the extraction steam of the regenerative heater. 

[Results] When a single high-pressure heater is pumped and throttled, the load response ability of No.1 high-pressure heater is the strongest. The maximum variable load under 75%THA, 50%THA, 40%THA and 30%THA conditions is 7.27 MW, 4.61 MW, 3.47 MW and 2.42 MW, respectively. In addition, this adjustment method has the most obvious influence on feed water temperature and heat consumption rate. When multiple high-pressure heaters are combined for extraction throttling, the influence of combination one on load and feed water temperature is greater than that of combination two and combination three. Under 75%THA condition, the three combinations increase the unit power by 17 MW, 8 MW and 1.8 MW respectively, and the final feed water temperature decreases by about 61.7 °C, 27 °C and 9.8 °C respectively. Through the synchronous adjustment of three high pressure heaters through the large bypass of the feed water, th e greater the bypass flow, the greater the variation of the unit power and the feed water temperature, and load change rate is about 0.038 MW/(t·h-1) under the 75%THA condition. When throttling the lowpressure heater extraction steam, the load response ability of cutting off a low-pressure heater extraction steam alone is very poor. Due to the reaction of the coupling of the thermal system, the unit power does not rise but falls. After switching to condensate throttling and adjusting the extraction steam of four low-pressure heaters at the same time, the load response ability is enhanced, and load change rate of the unit is 0.021 MW/(t·h-1) under 75%THA condition. 

[Conclusion] The load response capacity of the high heating side of the regenerative system is much larger than that of the low heating side, and there is a step difference. The stronger the load response ability is, the higher the sacrifice and control difficulty of feed water temperature are. There is a reverse effect of single throttling on the low pressure side, and only the overall adjustment is meaningful.