Performance Variation And Fault Diagnosis Of Gas-steam Combined Cycle Steam-water Systerm

Gas-steam combined cycle technology is a widely used and promising clean energy power generation technology.The steam system is an important part of gas turbine combined cycle unit.The health monitoring of its equipment is of great significance to the efficient and stable operation of the combined cycle unit.If the equipment with a potential fault in the steam system is detected and located,maintenance can be arranged in advance,and on-condition maintenance can be realized based on the situation of the equipment.The steam system of an S109 FA gas turbine combined cycle unit in Huaneng Jinling Power Plant was selected as the reference.Referring to the heat balance diagram of this unit at the operation condition of ISO 100% load,the off-design condition model of the steam system is established through the equipment characteristic equation and semi-empirical formula,and the performance degradation coefficient of the heating surface of the heat recovery steam generator,and that of the steam turbine at each stage are defined.Different types of frequently emerged faults are introduced and criteria of the steam system are discussed.The fault diagnosis models are established.A software module to calculate the performance degradation of the steam system of a combined cycle is developed with C++ programming language,which includes data acquisition,data preprocessing,data calculation,data storage and chart drawing.The calculation can be carried out on-line and off-line.The performance degradation of a S109 FA gas turbine combined cycle steam system is calculated and analyzed using the developed software module.According to the stable operation data of the unit in recent two years,the performance degradation coefficient of steam cycle is calculated.Taking the performance degradation curve of each device as the benchmark,the real-time performance monitoring of each device is realized.Finally,the software module is used to analyze and diagnose the abnormal phenomenon in the data of low-pressure steam system of a S109 E gas turbine combined cycle unit.According to the results calculated from the data,it can be clearly seen that there is an abnormality in the low-pressure evaporator.The results are consistent with the site inspection results,thus verifying the correctness of the fault diagnosis model.