Search

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. © 2012 IEEE.

Continuous power quality (PQ) surveys of electricity networks generate large amounts of data that must be condensed for the purpose of interpretation and reporting. In this paper, summary indices for continuous PQ disturbances are calculated from distribution network data, and the relationship between these indices and the known physical characteristics of the site is investigated. Results from this survey prompted further analysis into the relationship between voltage harmonic distortion (THDv) levels and variation in load characteristics across the monitored sites. Accepted explanations for variation in THDv are evaluated against the observed levels and alternative explanations are proposed.

The Australian long term power quality monitoring project now involves over 500 sites over 5 years and is one of the largest and longest running in the world. The project necessitated the development of a monitoring strategy, including choosing the number of sites, the type of disturbances to monitor and a means of collecting information from a variety of instruments. The presentation of such a large amount of data must consider a variety of needs from the wide view of the network manager to the needs of area managers for details on specific sites. A key feature of the survey is the ability of different distributors to compare themselves with others. New indices have been developed, particularly for voltage sags.

This paper presents the design of a light chamber which can be used to investigate the flicker behaviour of various types of lamps. Using this system, a lamp can be subjected to a controlled voltage waveform while current and illuminance of the lamp are monitored. With the aid of such a voltage source capable of generating voltage fluctuations, including interharmonics and other power quality disturbances, the relationship between waveform and light flux fluctuation can be modelled. Such a system can be easily built with off the shelf equipment, but the cost would be prohibitive. To circumvent this problem, the design has been based on a combination of custom hardware, generic hardware and the LabVIEW software. The paper focuses on the various trade offs of the design as well as its initial usage with incandescent lamps and shows the how the system can be used for the verification of the model that describes the flicker behaviour of the lamp.