Abstract: In the context of the dual carbon goals and the large-scale grid connection of new energy, traditional thermal power units urgently need to enhance operational flexibility to meet the demands of grid peak shaving and frequency regulation. The condensate throttling technology alters the steam flow to the low-pressure cylinder of the turbine by adjusting the condensate flow rate, enabling a rapid response in unit output power. In order to study the dynamic response characteristics of the thermal power unit's regulation process under condenser water level disturbances, a dynamic thermal model of a 600 MW supercritical reheat unit was constructed based on the Dymola simulation platform in a Modelica language environment. The model is built on the theoretical foundations of mass conservation, energy conservation, and the basic laws of heat transfer, with modular modeling of equipment such as boilers, turbines, condensers, deaerators, high-pressure heaters, and low-pressure heaters, as well as incorporating steam temperature control and water level control systems. The former maintains the stability of main and reheat steam temperatures by adjusting the flow of cooling water, while the latter dynamically adjusts the pump speed or valve opening based on water level deviations. By applying step disturbances of 0.1 m to 0.5 m to the condenser water level at four typical operating conditions of 100%, 90%, 50%, and 40% rated load, the dynamic response characteristics of key parameters such as condensate mass flow and unit power can be analyzed. The results show that under the same operating load, the greater the water level disturbance of the condenser, the greater the increment of the output power of the corresponding unit. Under different operating loads, under the same condenser water level disturbance, the unit in high load operation, condensate mass flow overshoot is small, and it is easier to achieve stability, at the same time, when running high load, the output power response speed of the unit is faster, and the increment of the output power of the unit is larger, and the output power increment of the group is 0.85−5.68 MW when the load is high, which is more obvious than the power increment of 0.36−2.26 MW under low load.