Abstract: Compared with the theoretical calculation and the conventional test method, the global dynamic variable pressure test method is more suitable for accurately and completely describing the variable pressure thermal economic characteristics of steam turbines in terms of the accuracy of the analysis results, the convenience of implementation and the degree of close correlation with the flow characteristics of the control valve. The application of several units shows that the variable pressure thermal economic characteristics of steam turbines obtained by using this method can reflect the continuous change trend of the heat rate of the unit with the different initial pressure of the feasible valve range under the certain electric power which not only enables to clearly exhibit the inherent law of the variable pressure operation for different types of steam turbines; but is also helpful for the quantification of the influence of the regulating valve throttling frequency modulation and the regulating valve overlap degree on the heat rate of the unit. This method is greatly applicable in the electric power production process. The study can provide the technical reference for the technical and economic comparisons of the wide load peaking operation mode of the coal motor unit, the comprehensive optimization of the steam turbine and its control strategy.

Key words: steam turbine, steam distribution mode, operation mode, variable pressure operation, thermal characteristics