Abstract: For the operation curve of the coordinated control system of the supercritical throttling steam turbine with additional supplying steam at overload in practical application, the primary and secondary frequency regulation is limited and abnormal low-load jump coordination happens, which endanger the security of power stations and grids. Through changing the main steam pressure continuously with small steps, using the model for variable pressure operation quantitative calculation and taking full account of the mutual coupling between the main variables of the thermodynamic system, the overall dynamic optimization of the unit heat rate is realized in the same load sliding pressure operation range and the trend of the heat consumption is obtained, which becomes a guideline for the safe and efficient operation of the unit.

Key words: steam turbine, throttle steam distribution, additional supplying steam at overload, overall optimization, variable pressure operation