Research On Evaluation Method Of Thermal Power Unit Performance Index Based On Operation Data

In recent years,with the rapid development of new energy sources such as wind energy and solar energy,traditional thermal power unit is facing new problems such as low annual utilization hours,long downtime and frequent participation in deep peak shaving,which increase the difficulty of steam turbine thermal performance test,causing long test time and low tester's work efficiency,which is not conducive to the performance optimization of thermal power unit.Therefore,it is very necessary to use the operation data to analyse and evaluate the performance of thermal power unit,which is of great significance for performance monitoring,operation optimization and fault detection of thermal power unit equipment and system.Based on the above analysis,this paper proposes to take a few key operation points as the landing point,and find the appropriate steady-state condition through effective steady-state detection method,which is to control the random uncertainty of measurement within the allowable range,so as to achieve good repeatability of measurement.At the same time,the data statistical theory is adopted to evaluate the selected qualified working conditions,which improves the reliability of the monitoring results of performance index.Therefore,a short-period daily performance monitoring system of thermal power units with low uncertainty and good repeatability of monitoring results,low cost and low difficulty in the implementation process is established by using field operation data.In this regard,the main work content and conclusions are as follows:(1)Based on the analysis of the consumption difference of the thermal power unit by EBSILON software,meanwhile,the influence of main operating parameters on the calculation results of turbine performance index uncertainty is considered,more than 10 key operating points are extracted and the measuring points are standardized.The main feed water flow measurement is recommended to permanently install the low ? value throat pressure nozzle at the economizer inlet,its uncertainty is 0.25%.The critical pressure measuring point is recommended to be measured by a pressure transmitter with an accuracy level of 0.1%.The critical temperature measuring point is recommended to be measured by a temperature measuring system with an uncertainty of 0.5°C,and a double measuring point arrangement is adopted.(2)Starting from the calculation principle of the minimum number of readings of performance test,the stochastic uncertainty of the performance index calculation result caused by controlling the reading dispersion of each main operating parameter is within the specified range,a suitable steady-state detection is proposed,which is to select suitable steady-state conditions.Compared with the sliding window method,the steady-state detection method has higher detection sensitivity and accuracy,which can effectively improve the steady-state accuracy and reliability of the system identification,and can adaptively determine the length of the interval.(3)Based on the historical operation data of a certain ultra-supercritical 1000 MW thermal power unit,the calculation,correction and evaluation methods of steam turbine performance index are emphatically studied,and the relative variation of characteristic flow area is used to evaluate the auxiliary steam consumption and steam leakage.The results show that after the correction of main parameters,auxiliary steam consumption and steam leakage,the maximum calculation deviation of steam turbine heat consumption rate under the same load and with the same high profile valve opening is 83.3 k J?(k W?h)-1 of each month.The method estimates the confidence interval of the monthly mean heat consumption rate,and finds that the maximum confidence interval of the heat rate is 40.2 k J?(k W?h)-1,that is to say,the maximum calculated heat consumption rate is 0.52%.In this way,the repeatability and reliablity of the performance index monitoring results are improved effectively.This method can be further extended to the monitoring and evaluation of other performance indexes of thermal power units,which has certain guiding significance for the research of thermal power unit equipment fault warning and performance degradation trend.