Diagnosis of Oscillation and Vibration of Dry-Type Transformers Caused by Harmonic Resonance

Abstract

This paper has investigated the oscillation and vibration of dry-type transformers under harmonic current and resonance system. Power dry-type transformers are the equipment being critical for the availability of electrical energy networks. Prevention of failures gains importance considering outage time and resulting subsequent costs. Therefore, permanent monitoring of dry-type transformer is used. The inspection begins with turning off the electric load of the heater, resulting in a completely silent sound and no vibration. The analysis results from the data can show that resonance occurs in electrical systems at frequencies in the range of 100, 150 and 1,150 Hz. Modifying and controlling the harmonic level by installing a Hybrid Power Filter System (HPFs) which uses the Passive Power Filter System (PPFs) to filter the harmonic current down first and then using the Active Power Filter System (APFs) eliminates the remaining harmonics in the system. The harmonic filtering operations of PPFs and APFs are independently separated, with the PPFs positioned near the electrical load and the APFs positioned near the transformers. Finally, the harmonic current can be reduced to a very good level of about 3%. As a result, the dry-type transformers do not make sound, do not oscillation or vibrate.