Research On Varying Condition Characteristics And Optimization Of Steam Turbine

Thermal power plant is a large primary energy-consuming industry. The in-depth study of the operating characteristics and economy improvement of the thermal power plant process has an important significance for enhancing the competitiveness of the thermal power plant. Meanwhile, it also has great strategic significance to the economic and social sustainable development. Therefore, the field tests, the model of unit dynamic characteristic, thermal economic analysis and optimization of steam distribution were studied in this paper based on a nozzle governing 300MW steam turbine unit.Firstly, the field tests were studied on the object unit, including step response test of turbine load and rapid peak-load test, in order to obtained the step response characteristics of the governing valve under different loads, meanwhile the fastest lifting load rate in case of the operation security concerns has been obtained according to 75%ECR-55%ECR down-load test, which provides reference for similar units, and provides test data for subsequent modeling and optimization.Secondly, the object steam turbine and thermal system was modeled based on APROS modular modeling system using the unit design data, then according to the dynamic characteristics of test data the model was debugged and the reliability was verified. With the established detailed model based on APROS, the influences of three factors on the unit security and economic analysis were analyzed quantitative under typical operating conditions, including the main steam temperature and back pressure. The obtained various factors on the power and heat rate correction curves provided reference for the actual economic analysis under the actual variable operating conditions.Then, the flow coeddicient of governing valve, the combined flow characteristics curve of governing valve and governing stage was obtained by the varying condition calculation, and the theoretical calculation model was established, which could be used to debug the APROS model. Based on the former study of degree of overlap, the flow characteristic curve of governing valve is calculated by the debugged model, and was then compared with the governing valve characteristics test to verify the correctness of the model. Then, the thought of combined with load and valve position was applied to analyze the steam distribution optimization, and the model was verified by the actual operation data. The best steam distribution mode and the optimal main steam pressure curve were obtained at last, and the theoretical mathematicsl model of main steam pressure with heat consumption was established, which provided a direction for further optimization, and make up the difficulty of field optimization test. For object units backpressure affected significantly by the season, the main steam pressure curve clusters and the main steam pressure logic correction curve of the back pressure was obtained according to the best steam distribution mode.Finally, the advanced firefly intelligent optimization algorithm was introducted to discuss the advantages and disadvantages in solving different problems compared to the standard particle swarm optimization algorithm. Then according to the coal consumption characteristics curves obtained from the detailed calculation model, and the effectiveness of the FA was verified compared to the traditional compound shape method, then full plant economic load dispatch was calculated by the FA under different fastest lifting load rate.