Cleantech research firm Navigant reported that for many utilities the focus of their smart grid efforts is shifting from advanced metering infrastructure (AMI) to the larger issue of distribution automation (DA), “intended to reduce capital and operating costs, as well as improve the efficiency and quality of the power grid.”
Navigant defines distribution automation as “intelligent distribution systems that are fully controllable and flexible, and that can help operate the grid more efficiently due to their embedded intelligence.” The technology “can play a critical role in outage recovery, delivering the capability to sense and pinpoint faults, reroute power flows through dynamic sectionalizing, and even provide key location information back to line crews to speed repair and recovery.”
By 2020, the firm forecasts, “more than 15 percent of the global installed base of smart meters will be incorporated in functional AMI/DA systems, … up from 2 percent in 2012.” Navigant has estimated that global revenues from DA systems will grow from $6.3 billion this year to more than $11.3 billion by 2020. The growth in DA is in part driven by the “proven reliability improvements and verified grid efficiencies” experienced by utilities during smart grid pilots in recent years.
Renewable energy introduces significant variability into the electric grid, increasing the value of automation in the distribution network. Donald Henschel, energy analyst at research firm IHS, stresses the connection between DA and renewable energy, writing for AltEnergyMag:
A widening range of electrical industry suppliers as well as their utility customers are becoming keenly aware that the promise of renewable energy, electric vehicles, and the greater smart grid will not be realized before extensive automation upgrades are made along electricity distribution networks.
From Passive to Active Management
According to Cardiff University engineering professor Janaka B. Ekanayake, writing with colleagues in their book Smart Grid: Technology and Applications, DA is needed to solve growing problems associated with electrical distribution. Currently, utilities manage electrical generation and transmission networks using supervisory control and data acquisition (SCADA) systems, which “link the various elements through communication networks … and connect the transmission substations and generators to a manned control center.” In larger networks, area control centers are coordinated by regional centers.
“Traditionally, the distribution network has been passive with limited communication between elements,” writes Ekanayake. Automation is generally limited and localized. However, the need for automation has been increasing over the past decade, particularly to “improve the quality of supply and allow the connection of more distributed generation,” which is causing increasing network voltage changes and fault levels. This trend is prompting a “shift from passive to active management of the distribution network.”
DA automates the process of detecting faults and restoring supply, as well as controlling voltage variation. At the equipment level, wireless intelligent electronic devices (IEDs) are a crucial element, providing measurement, recording and monitoring of system components. Remote terminal units (RTUs) are used to receive data from IEDs and to act as interfaces with the operations center. Switchgear is increasingly being outfitted with actuator mechanisms that automate the process of isolating a faulted section of the network and restoring it with reclosers when the fault has been corrected.
Raleigh, N.C.-based Sensus provides DA solutions in place at over 200 utilities globally. Sensus’ solutions are made up of three primary elements: IEDs; a PowerVista software suite for managing those devices; and wireless network solutions, which can employ either commercial cellular networks or Sensus’ FlexNet radio network. Sensus manufactures a variety of networked intelligent field devices, including reclosers, capacitor banks, relays, voltage regulators and switch controls.
Greg Myers, marketing vice president for Sensus, told Green & Clean Journal that DA systems are already helping utilities operate more efficiently through “better handling of faults and outages or monitoring the voltage and adjusting it at different points so you have good quality of power.” With DA, “you’re doing it through automation instead of putting a truck out there and having a man do it manually.”
In the future, though, said Myers, DA will allow more proactive network management. As an example, “today, utilities have got a sense somewhat of how their distribution is laid out. But they really don’t get the data telling them when they are overloading transformers.” He cited the example of consumers’ moving from California to Colorado in the 2000s. “Utilities in Colorado had a lot of transformers blown from people wanting to have air conditioning. If they had had the data, they could have gone out and prevented a lot of transformer overloads” by building out ahead of time. That’s just an example, but it demonstrates that “utilities can more proactively monitor and head off any problems and get the most bang for their buck” in such areas as “putting out new distribution lines … if they can have tools to help them develop, plan and manage the network.”
ComEd’s DA Deployment
Chicago-based utility ComEd plans to spend $2.6 billion over the next 10 years to modernize the electric grid in Northern Illinois, including $1.3 billion for deploying a smart grid system and smart meters for four million homes. Ahead of those smart meter deployments, ComEd has already started its DA rollout, investing $32 million in 2012 and upping that to $44 million for this year. For the first year, the utility installed 470 DA devices.
ComEd VP Mike McMahan, who heads up smart grid and technology for the company, commented in a company announcement that “Just as today’s smart phone technology merged the power of computers with cellular phones, smart grid technology merges the power of computers with the electric grid.” According to the utility, installation of the DA devices resulted in 82,000 fewer service interruptions last year.
As an example of its benefits, McMahan said:
With distribution automation, if a tree were to fall on a utility pole resulting in an interruption, far fewer customers would be impacted because it enables us to better isolate the damaged section. DA introduces a self-healing capability to the electric grid by allowing us to resolve issues before customers might even be aware of them.
ComEd expects to complete its DA rollout by 2018 and its smart grid by 2022. Once it is fully implemented, system communications will automatically alert the utility’s operations center about any outage without any need for customers to call in. DA provides added intelligence that expedites the dispatch of repair crews. Smart meters will inform the center once power is restored.
In spite of the value and necessity of distribution automation for smart grid effectiveness, Navigant stresses that rollouts won’t necessarily be painless. An overlay of DA on top of AMI deployments should yield financial benefits, says the research firm, but the integration of AMI and DA is far from “a slam dunk”:
Potential obstacles can be found in the robustness of the AMI system’s underlying communications network, in organizational silos where different departments may lack experience with systems and protocol interoperability, and in the management and analysis of the expected vast volumes of data.