In Australia and many other countries, distribution network service providers (DNSPs) have an obligation to their customers to provide electrical power that is reliable and of high quality. Failure to do so may have significant implications ranging from financial penalties theoretically through to the loss of a license to distribute electricity. In order to ensure the reliability and quality of supply are met, DNSPs engage in monitoring and reporting practice. This paper provides an overview of a large long-running power-quality monitoring project that has involved most of Australia's DNSPs at one time or another. This paper describes the challenges associated with conducting the project as well as some of the important outcomes and lessons learned. A number of novel reporting techniques that have been developed as part of the monitoring project are also presented. A discussion about large-volume data management, and issues related to reporting requirements in future distribution networks is included.Abstract -In Australia and many other countries, distribution Network Service Providers (DNSPs) have an obligation to their customers to provide electrical power that is reliable and of high quality. Failure to do so may have significant implications ranging from financial penalties theoretically through to the loss of a license to distribute electricity. In order to ensure the reliability and quality of supply are met, DNSPs engage in monitoring and reporting practice.This paper provides an overview of a large long-running power quality monitoring project that has involved most of Australia's DNSPs at one time or another. The paper described the challenges associated with conducting the project as well as some of the important outcomes and lessons learned. A number of novel reporting techniques that have been developed as part of the monitoring project are also presented. A discussion about large-volume data management, and issues related to reporting requirements in future distribution networks is included.
The rollout of advanced metering infrastructure, advanced distribution automation schemes, and integration of generation into distribution networks, along with a raising of awareness of power quality (PQ), means that there is an increase in the availability of power system monitoring data. In particular, the data for harmonics, whether it is voltage or current harmonics, is now available from a large number of sites and from a diverse range of PQ instruments. The traditional analysis and reporting of power quality examines harmonic orders to the 50th. This means that the harmonic data available for analysis are significantly larger than, for example, steady-state voltage variations where only a few parameters are examined (e.g., the voltage on each phase). Higher frequency components, sometimes called highfrequency harmonics, in the 10-250 kHz range arising primarily due to power-electronic interfaced generation are also becoming significant. Given the vast amount of harmonic data that will be captured through grid instrumentation, a significant challenge lies in developing methods of analysis and reporting that reduces the data to a form that is easily understood and clearly identifies issues but does not omit important details. This paper introduces a number of novel methods of analysis and reporting which can be used to reduce vast amounts of harmonic data for individual harmonic orders down to a small number of indices or graphical representations which can be used to describe harmonic behavior at an individual site as well as at many sites across an electricity network. The methods presented can be used to rank site performance in order for mitigation strategies. The application of each method described is investigated using real-world data.
At the core of the MPEG-21 Multimedia Framework is the concept of the Digital Item, a virtual container for a hierarchical structure of metadata and resources. This paper considers the Digital Item Declaration Language (DIDL), gives examples of its usage, and discusses how it is used to integrate other parts of MPEG-21. The paper then discusses how Digital Item Identification integrates with the DIDL to allow MPEG-21 to utilize standard identifiers from many application spaces. Finally, an alternative, compressed form of the XML Digital Item Declaration is described. This uses schema-based compression to significantly reduce the size of these XML documents. Abstract-At the core of the MPEG-21 Multimedia Framework is the concept of the Digital Item, a virtual container for a hierarchical structure of metadata and resources. This paper considers the Digital Item Declaration Language (DIDL), gives examples of its usage, and discusses how it is used to integrate other parts of MPEG-21. The paper then discusses how Digital Item Identification integrates with the DIDL to allow MPEG-21 to utilize standard identifiers from many application spaces. Finally, an alternative, compressed form of the XML Digital Item Declaration is described. This uses schema-based compression to significantly reduce the size of these XML documents.
The ITI curve developed by the Information Technology Industry Council (USA) describes an AC input voltage envelope, which typically can be tolerated by most information technology (IT) equipment supplied by nominal 120 V 60 Hz electricity networks. Although the curve ostensibly applies only to IT equipment supplied at 120 V 60 Hz it is often used throughout the electricity supply industry, including at other nominal voltages and frequencies, without modification or consideration of applicability to provide an indication of the input voltage tolerance of a wide range of equipment. This paper details a preliminary study aimed at developing an ITI style curve to suit 230 V 50 Hz electricity networks. A range of domestic and industrial equipment has been tested to determine voltage sag susceptibility. Overall, results for domestic appliances show that equipment connected to the Australian 230 V 50 Hz electricity network has voltage sag immunity considerably better than that defined by the ITI curve. The same may be said for the majority of industrial equipment tested. As such, the suitability of the ITI curve in describing a sag immunity envelope for individual pieces of equipment connected to 230 V 50 Hz electricity networks is highly questionable.
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