Noise and vibration survey of ac filter capacitors in Feng Xian HVdc converter station

The audible noise radiated from the ac filter capacitors in HVdc converter stations has become a serious environment problem. The purpose of this study is to apply portable digital vibrometer for in-situ surface vibration measurement of capacitors, to survey the vibration isolation and noise reduction effect of double-bottom capacitors which are installed in Feng Xian Converter Station for the first time, and to analyze the vibration and noise characteristics of ac filter capacitors. Portable digital vibrometer is a new technology using eye-safe visible laser and digital signal processing to conduct non-contact on-line vibration velocity measurement. The vibration of capacitor surfaces and steel frames are measured and amended according to the measuring elevation angle. On the other hand, the noise at the points arranged around the rail of filter field is measured by NA28 sound-level meter and 1/3 octave band realtime analyzer. The data and analyses show that the main frequency component in vibration spectrums of capacitor surfaces and steel frames are both 100Hz. And as the doublebottom design being adopted, the vibration at bottom surface decreases obviously. Besides, the noise at the side near the top surfaces of capacitors is much higher than that at other places.