Distribution Automation: Are You Missing Out on the Advancements?
- Feb 18, 2011
- Andrew Hanson
Until recently, Distribution Automation (DA) had been developing slowly. That changed in the past couple years as deployments have been accelerated at many utilities, moving beyond pilot or demonstration projects to wide-scale initiatives for capacitor control and switch/recloser automation. This acceleration coupled with relatively recent emergence of dedicated distribution SCADA (DSCADA) platforms for monitoring and control of the DA devices has enabled a variety of new DA trends. These trends include automated restoration (including fault location, isolation and restoration) to improve reliability and integrated Volt/VAr control to reduce demand and losses. These applications have been supplemented with deployment of fault indicators and feeder monitors/meters to provide additional data. An overriding question is whether these deployments are solely the result of DOE funding or are initiatives that utilities would have pursued regardless. We believe the deployments would have proceeded, but at a much slower pace based on the observation that several utilities are moving forward in this area even without external funding.
Automated isolation and restoration is enabled via automated reclosers, sectionalizers and / or automated switches that support location, isolation and restoration following a fault in order to improve reliability. Much of the isolation is performed in a relatively traditional manner using the protection functions of reclosers. The change from a more traditional approach involves the location and restoration of customers following a fault. Modern reclosers can be used to restore customers in un-faulted portions of a circuit via centralized remote control or via “local” logic in the field. In planning a DA deployment, there are a number of issues to be considered including: tagging procedures, coordination, “local” versus centralized control and, model maintenance procedures. Future blogs will discuss these issues in greater detail.
Integrated volt var control (IVVC) takes a number of forms, the simpler of which may include straightforward control of load tap changers to reduce feeder voltage, or pager based capacitor control to manage overall circuit power factor. More complex implementations integrate control of load tap changers and capacitors and may even include widespread deployment of voltage regulators (even in urban and suburban areas!) and upgrade of certain line sections contributing disproportionately to overall circuit voltage drop. There are two principal drivers for such installations: 1) loss reduction and 2) peak demand and energy reduction through reduced operating voltage, which may allow deferment of power plant construction. There are a number of issues that implementers of such systems are facing including: how to measure impacts, how and whether these distribution assets should be used for transmission benefit and ultimately whether the systems achieve their targeted goals.
One of the exciting recent developments is that equipment used for DA implementations has begun to evolve at a much faster rate, with products from new market entrants and innovative products from established suppliers. Among these products are lower cost metering devices for capturing data from various points along distribution feeders, which will provide real time visibility along feeders that has not been available previously. An additional area of rapid evolution is with faulted circuit indicators. These aren’t the faulted circuit indicators of twenty years ago, but intelligent devices that have the ability to provide not only fault passage, but indication of current magnitude during faulted and un-faulted periods. In essence faulted circuit indicators may become “pseudo meters” providing a snapshot of the current at key points on distribution circuits. The data from these devices can be brought back to a DMS and/or OMS to provide fault location information, outage and restoration notification, potentially providing a significant improvement in responsiveness.