Research And Application Of Remote On-line Monitoring System For Hydroelectric Generators

With the rapid development of hydropower development in China,the number of hydropower stations under the Power Generation Group has increased to a certain scale.The implementation of "bidding on the internet" puts forward higher requirements for the safety,stability and economic operation of power generation equipment.The operation status data of units in hydropower stations are transmitted to the group center,and a unified data platform is established to realize remote monitoring and fault analysis of units,which can reduce service costs and improve the economic benefits of enterprises.The remote on-line monitoring system takes the hydroelectric generating unit as the research object,adopts the Internet network transmission technology,realizes the data transmission from the spot to the group center,and designs many kinds of analysis atlas,such as time domain analysis and frequency domain analysis,to realize the status data analysis and fault diagnosis of the unit.Firstly,the structure design of the remote on-line monitoring system for hydroelectric generating units is described.According to the structure and operation characteristics of hydroelectric generating units,the monitoring requirements of the system are analyzed.The three-tier structure of the system is designed based on network transmission technology.The data acquisition layer is set up in each power station,mainly including sensors and data acquisition devices,which collects and transmits vibration signals of the unit;the central service layer is set in the group center,mainly including data server and application server,which is responsible for data storage and distribution of the whole group;the system application layer refers to the client on the network,using system application software to analyze data and to the unit.Fault diagnosis is carried out.The system adopts data mirror transmission technology and double compression technology.Servers are set up on the power station side and the central side respectively.Real-time databases are installed to realize long-distance large data transmission.Secondly,the system signal acquisition and data analysis are described in detail.The sampling principle of data is introduced.The continuous analog signal is transformed into discrete digital signal.The principle of Fourier transform is emphasized,and the waveform signal is transformed into spectrum signal.Various analysis functions in time domain analysis and frequency domain analysis are designed,including waveform analysis,spectrum analysis,axis trajectory analysis,correlation analysis and so on.Combining with the vibration standard of the hydro-generator set,the first-level alarm strategy and the second-level alarm strategy of the system vibration swing are formulated.Thirdly,the rotor mass unbalance fault of hydro-generator unit is studied,and the principle of unbalance is briefly described,as well as how to use the influence coefficient method to realize the dynamic balancing of the rotor.Combined with engineering cases,the main monitoring chart function,data table function,spectrum analysis function and correlation trend analysis function of the system are used to diagnose the rotor mass imbalance fault of the unit,and the peak value,1X frequency amplitude and phase of the unit are used to calculate the mass and dynamic balance influence coefficient of the test weight in the dynamic balance test,and the data before and after the balancing are compared.Finally,the common faults of hydroelectric generating units are studied.Three engineering cases are selected from three aspects: mechanical factor,electromagnetic factor and hydraulic factor,such as too large bearing clearance,unbalanced magnetic pulling force and tailrace vortex belt.The vibration characteristics of the unit are obtained by using the functions of waveform analysis,spectrum analysis and trend analysis of the system,and the fault diagnosis of the unit is carried out.