The influence of nonlinear loads on the power quality of the New Zealand low voltage electrical power distribution network

Reducing electrical consumption by eliminating large inefficient loads and introducing smaller more efficient loads, results in large, conventional, linear loads being replaced by smaller modern nonlinear loads. Their electronic front ends make these nonlinear loads more efficient, but they inject harmonics into the power network, bringing total harmonic distortion in New Zealand to near our limit of 5%. To date this has largely been ignored, as most of the existing load is still linear and modern nonlinear devices are small, so the average load power factor is still close to unity. But as large linear loads are increasingly replaced by multiple smaller nonlinear loads, the combined effect can be detrimental and hard to mitigate due to the distributed nature of these many small disturbing nonlinear loads. This research summarises and analyses the available research on the effects of widespread adoption of nonlinear loads on the power quality of the weak New Zealand electrical power distribution network. Conclusions drawn from this analysis are used to further investigate the issue by measurements in the laboratory and in homes, providing a helpful source of information for future wider investigations and mitigation initiatives recommended by this research.