Mains Signal Propagation through Distribution Systems

This paper looks at a power quality problem termed “Racing Clocks” caused by the amplification of ripple frequency signals in distribution networks. A study of this problem has been undertaken on two 22kV feeder systems within the Sydney area. These two particular feeder systems were chosen as they have caused problems in the past. The purpose of this study was to determine whether the problem still exists in the areas supplied by these feeders. The present and ultimate configurations of these two feeder systems are examined and the resonance frequencies and ripple signal voltage levels are determined. Modelling techniques that were adopted in the simulation are also described. The study showed that for certain ratios of overhead to underground cable, the resonance point might occur near a problematic frequency.