In the context of constructing a new power system

the flexibility of coal-fired units is crucial for accommodating fluctuating renewable energy. The condensate throttling method plays a key role in enhancing unit flexibility by fully utilizing the thermal storage of the steam turbine. This paper establishes a 600 MW supercritical condensing steam turbine system model based on the Modelica language. The model is simulated using Dymola simulation platform and validated against the design values. By analyzing the transient response characteristics of the power regulation under different throttle flow rates

the study further explores the unit’s responsiveness to variable loads under different operating conditions. Additionally

dynamic exergy flow and exergy loss are analyzed for reheat system. The results indicate that both the change in unit power and the maximum response speed are positively correlated with the throttling flow rate. Under different working conditions

the power increment exhibits an exponential relationship with the condensate flow rate. Compared with the 50% turbine heat acceptance (THA)

the maximum power increment increases by 64.5% and 105.4% under 75% and 100% THA. Dynamic exergy analysis reveals that the stored thermal energy in the regenerative heating system is progressively released along the condensate flow path

leading to a new thermodynamic equilibrium. The total exergy loss and dynamic exergy response coefficient of the deaerator and 1# low-pressure heater are higher than those of the remaining low-pressure heaters. The total exergy loss is distributed across the deaerator

1#

4#

3# and 2# low-pressure heater in descending order. Therefore

condensate throttling enhances rapid load regulation

with its load-dependent nonlinear response driven by the dynamic release and redistribution of stored energy in the regenerative heating system.