Sound Intensity Survey of the Comerford HVDC Converter Station

The purpose of this EPRI study is to demonstrate and deploy acoustic intensity for in-situ sound power measurements of converter-type transformers and to rank order all other noise sources at the Comerford High Voltage dc Converter Station. Sound intensity is a new technology using two closely-spaced and phase-matched, pressure-sensitive microphones to approximate one component of the intensity vector. Sound intensity measurements made at the Comerford station are used with geometrical considerations and Gauss\´ law to compute individual noise source strengths despite interference and reverberation. The data and analyses show that over 84% of the noise is radiated by the harmonic filters. Another 12% can be traced to the converter transformers. Our analysis also shows that noise levels increase in "loaded" versus "unloaded" converter transformers by nearly four times. The results support the claim that sound intensity has applications in the power distribution industry as a diagnostic tool for quantifying transformer noise. The results also indicate where noise reduction efforts should be concentrated at the Comerford station.