Fault diagnosis system for regulating system of th

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Turbine governing system fault diagnosis system

Chinese figure classification number: tk263.72, Tp277 document identification code: a

article number: 1001-2060 (2000) 03 - failure diagnosis system for a steam turbine regulating system fill in the thread pitch here, then Bao Wen Yu Daren Li wenzhu

(College of energy science and engineering under the Harbin Institute of technology, Harbin, China, post code 150001) With the help of the failure metallographic polishing machine use knowledge e diagnosis system of a steam turbine regulating system it is possible to record the variation trend of the key parameters of the said system The realization of such functions as the on-line calculation of steam turbine static characteristics, the detection of pilot valve stuck status and the regulating system oscillation failure diagnosis can result in a significant enhancement of the operating safety of the regulating system. Moreover, the above also plays a positive role in the preventive maint does not simply mean the technology and product innovation inception and repair of the regulating system

key words: steam turbine, regulating system, failure diagnostics preface turbine machinery is a high-speed rotating machinery, and the operation state of its regulating system is directly related to the safety of the unit. A vicious accident of overspeed and destruction caused by multiple regulating system faults has occurred []; On October 29th, 1985, a 200 MW steam turbine in a power plant in Shanxi Province lost load. The speed control system was out of control, resulting in the overspeed of the unit and the scrapping of the whole machine, resulting in huge losses; In 1993, the 300 MW steam turbine of a power plant in Guangdong Province was overspeed during load rejection due to the jamming of the regulating valve rod, and the maximum speed was 4200 R/min. fortunately, no serious damage was caused. In normal operation, there are many cases of abnormal conditions such as sudden load change, speed fluctuation and insufficient load caused by regulation system failure; According to statistics, 1/3 of the abnormal shutdown of the steam turbine is caused by the failure of the regulating system. Many research and production departments have carried out the research on the fault mechanism analysis and monitoring and diagnosis methods of the regulation system, and have made some achievements in the methods and mechanisms of fault diagnosis [3 ~ 5]

the regulation system fault has been highly valued by the power production department, but because the turbine regulation system fault diagnosis involves a wide range and many contents, so until now, there are few regulation system fault diagnosis systems running on site in China, so it is urgent to establish a practical regulation system fault diagnosis system. On the other hand, the regular maintenance of large units has gradually transitioned to predictive maintenance, and the fault diagnosis of regulation system is the basis of predictive maintenance of regulation system. Therefore, it is very necessary to develop the fault diagnosis system of regulation system. 2 regulation system fault diagnosis system structure in order to meet the needs of predictive maintenance and networking, the regulation system fault diagnosis system adopts Intranet structure. An industrial computer is set locally to carry out measurement, diagnosis, display and system setting on the network. The network connection of the system is shown in Figure 1. Fig. 1 the on-site signals with rapid changes in the hardware structure of the fault diagnosis system enter the local computer through the a/d board. These signals include: the upper and lower oil pressure of each slide valve, the position and power of the electro-hydraulic converter, the displacement of the hydraulic servo motor, the main steam pressure, the main steam temperature, and the pressure behind each regulating valve, etc; Some signals that change slowly or cannot be obtained through the acquisition board are obtained from the DAS system on the network, such as electric/hydraulic regulation status, oil switch status, CCS switching and other signals

the sampling period of the original collected data is 10 ms. due to the storage limitation of the computer, too much fast sampling data cannot be saved. Therefore, the system resamples the collected data to generate slow sampling data with a sampling period of 1 s. The system saves 2000 points of fast sampling data and 2000 points of slow sampling data at the same time for fault diagnosis. When the fault diagnosis system finds that there may be a fault or an operation, it will save the fast sampling data and slow sampling data at the same time, so that it can not only record the rapid change process when the fault occurs, but also record the change process of various physical quantities in recent time. In order to avoid storage overflow, the data ring structure is adopted for historical data storage. The system only saves historical data for a certain number of times. With the increase of storage times, new data will cover old data

the display of fault diagnosis system adopts browser mode. As a WWW server, the local computer can use the browser to view the current data, historical data and diagnostic results on any computer on the network. 3. Fault monitoring of governing system fault diagnosis system of steam turbine governing system includes fault monitoring and fault analysis. Fault monitoring includes the diagnosis of system operation characteristics, the judgment of the operation status of various components of the regulation system and other functions; The fault analysis is to analyze the fault source and give the fault Countermeasures after the fault occurs. The operating characteristics of the regulating system are mainly the static characteristics of the system, and the characteristics obtained from the static characteristics are unequal rate and retardation rate. Some monitoring and diagnosis algorithms are discussed below

3.1 calculation of the retardation rate of the regulating system

the retardation rate has a great impact on the normal operation of the regulating system, and the actual retardation rate is related to the retardation rate of each component of the regulating system. Spool valve retardation rate Δ C can be calculated with the following safe and reliable formula [6]: where q is the flow, P is the pressure, and the subscript x is the inflow end

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