Characteristics of power quality disturbance levels in Australia

The Australian Long Term Power Quality Survey (LTNPQS) now covers 2,000 sites with a range of different characteristics including strength (related to fault level), line construction and dominant load type. This paper details the latest outcomes of the LTNPQS project in terms of both disturbance levels and reporting methods. A comparison of the differences between voltage, unbalance and harmonic THD levels at strong (close to transformer) and weak (towards the end of LV feeders) sites has been performed and significant differences have been found. A multivariable linear regression study has been undertaken in order to investigate the correlation between site characteristics and PQ disturbance levels. Unexpectedly, little correlation could be identified. If true, this would mean that the overall PQ disturbance levels achieved by a utility may be estimated from a smaller set of sites than has been previously assumed.