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Study on Statistical Characteristics of Audible Noise and Vibration Signals of UHV Transformers and Reactors

Audible noise and vibration signals can reflect working conditions of transformers such as loose fasteners, winding deformation, and DC magnetic biasing, etc. In order to realize the transformer state assessment and early warning, noise and vibration signals are measured on site for 5 transformers, 4 shunt reactors, and 21 converter transformers. At least 4 measuring points are selected to collect noise signals, which include UHV transformer oil tank and cooler, the tank walls on both sides of the high-voltage bushing and the neutral point bushing. Meanwhile, 4–10 test points are arranged to measure vibration signals around the tested equipment, including the tap-changer, the iron core clamps, the high voltage bushing, and the tank wall near the cooler on both sides of high voltage bushing and the neutral point bushing. The parameters of SPL(Sound pressure level), vibration amplitude, odd-even harmonic ratio, high-frequency energy ratio, and spectrum complexity of the three types of test objects are statistically analyzed.