Semi-Empirical Simulation Model of Audible Noise From Corona Discharges

Water droplets on overhead power lines (OHL) cause electric field distortions that can be the source of corona discharges. The resulting audible noise is an annoyance for nearby persons and its allowed maximum intensity is limited and regulated by respective authorities. It is well known that different conductor types with different surface treatments provoke different audible noise levels and research is ongoing to understand the underlying phenomena to minimize audible noise emissions. This paper aims to contribute to the understanding of corona-induced audible noise on OHL by presenting and validating a semi-empirical simulation model. This model simulates the propagation of pressure distortions in air induced by corona pulses. As an input to the model, a linear relation between the electrical discharge intensity and the injected sound power amplitude is experimentally determined by single droplet measurements in an anechoic chamber. This holds true for water droplets of different volumes and in different electric field strengths. For the first time, the sound pressure around wetted OHL is simulated with only partial discharge (PD) measurements as input parameters. It is shown that the A-weighted sound pressure at different locations away from the conductor can be reliably simulated for single droplets and for fully wetted OHL lines with various different surface treatments and in different electric field strengths.