Statistical method for analyzing shaft orbit of hydro-generator
Fu Jing1, Zhang Fei2, Li Bing1
1.Department of Integrated Service, China Institute of Water Resources and Hydropower Engineering, Beijing 100038, China; 2.Department of Hydraulic Machinery, China Institute of Water Resources and Hydropower Engineering, Beijing 100038, China
Abstract:Because the methods for analyzing the shaft orbit of hydro-generator are very less presently, the shaft orbit cannot be monitored effectively in a long period of time in operation. In the paper, a few parameters, namely standard deviation, coefficient of variation, area and normalized area are defined for the shaft orbit based on statistic method, then the shaft orbits of the hydro-generator in a hydro-power plant were studied under various operational conditions at a fixed head by the parameters. It was shown that the clarity of shaft orbit can be described by the defined standard deviation and coefficient of variation. The influence of hydraulic parameters under various operational conditions on shaft orbit can be indicated by the coefficient of variation.Under the same working condition,the normalized areas measured at different locations have the same order and identical trend, so that effects of monitoring locations and bearing clearance adjustment etc on the orbit have been eliminated, eventually a general assessment of the shaft orbit can be made. The standard deviation and normalized area are sensitive to change in the shaft orbit caused from the variable operating conditions of a hydro-generator unit, thus they can be used in shaft orbit on-line monitoring of a hydro-generator unit.
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