Analysis of the incipient cavitation noise signal characteristics of hydroturbine

Hydroelectric power is widely used because of its environmental, renewable and green. The cavitation is inevitable phenomenon during the operation of hydroturbine which is related to the efficiency and service life of the unit. This paper is devoted to discriminate the phenomenon of the incipient cavitation, prevent the destruction early, and avoid the irreversible damage to hydroturbine. In order to find the characters of incipient cavitation. Use the method of wavelet time-frequency analysis and wavelet packet decomposition to process the cavitation noise signals. Use the value of peak factor and slope of power spectral density curve as a threshold when incipient cavitation to judge whether the cavitation occurs. The results shows that the characteristics of incipient cavitation can be detected in the auditory frequency band. The wavelet time-frequency analysis of noise signals can distinguish the different operating conditions, also can discriminate between the phenomenon of incipient cavitation and the other state of cavitation by visual observation. The wavelet packet decomposition can obtain the feature frequency of cavitation signal is 10-13 kHz. The way of judge whether the incipient cavitation happens by threshold value can reach the accuracy rate up to 70% which meet the requirements of the detection for incipient cavitation. (C) 2017 Elsevier Ltd. All rights reserved.