Substation automation to the smarter grid
IN THE DAYS BEFORE HURRICANE IRENE pounded the East Coast last August with wind gusts of up to 70 miles per hour and torrential rain storms, PECO mobilized its arsenal of field staff, local and national personnel, to respond to the record-breaking Category 1 storm. But equally important to those last-minute preparations were the steps PECO took in the almost two decades preceding the storm: beginning with the automation of its substations and continuing to present day with the installation of new smart-grid technologies.
"PECO was one of first utilities on the East Coast to have all its systems restored," said Glenn Pritchard, principal engineer, Exelon/PECO. "We had half a million customers off [of the grid]. To have them restored in five days is very significant."
PECO spent $45 million on storm restoration, an amount that could have been significantly greater.
"PECO saved in excess of $10 million during the fall hurricane by taking a single customer call and analyzing it to see what responders needed to go out," said Pritchard. The ability to learn about the breadth of an outage from one report was largely the result of different parts of PECO's automated system being able to make quick fixes and talk to one another, from the reclosers-devices that automatically restore short-circuits-to advanced metering infrastructure that enables two-way communications between the customer's meter and the utility.
Pritchard emphasized, in particular, that the pole-top reclosers allow PECO to "isolate an incident to few customers affected by an event," giving the utility the tools to restore the rest of the circuit in a few minutes.
Consolidating and automating
PECO's quest toward automation began in the mid-1990s. "PECO had an interest in modernizing the substation with better functionality, focusing on digital relays and more advanced relay schemes for transmission and distribution circuits," said Pritchard.
At that time, without widespread Internet use, "we needed banks of computers to monitor substations," he said. "What we found was that each of the systems required their individual system to operate. We tried to find ways to consolidate these systems into one platform."
PECO sought "a better way, both locally and remotely, to monitor, control, diagnose and maintain equipment in the substation to reduce operating costs and provide improved customer service," explains a case study written on the automation of its Westmoreland substation, which supplies about one-third of Philadelphia's electrical load.
"We looked at the different scenarios when things would alarm," said Pritchard, "and then we looked at how we could get ahead of these alarms-to be preventive instead of reactive."
The case study describes the renovation of Westmoreland in 1997 as "a complete turnkey transmission and distribution automation solution from system design through installation and commissioning."
This involved a microprocessor-based protective relay design that minimized maintenance costs through the use of self-checking and communications processors that collect and organize data from the relays to the transformers and breakers. The design ensured that the failure of any one of the protection or communication components would not prevent monitoring or control of any one of the 54 breakers and switches in the substation.
"The new design uses equipment on an unprecedented scale and is the largest single integrated system for protection, control, data acquisition, and monitoring ever undertaken by PECO," said Jack Leonard, PECO's principal engineer, in charge of investment strategy, at the time the case study was published.
The system increases the efficiency of substation maintenance through the automated reporting of relay-generated fault data and breaker trouble conditions, said the case study. "The customer not only has immediate fault location data to perform better and faster restoration, but also has detailed event reports automatically collected from the system. These event reports can be viewed in a graphic format to analyze system operation. These data can help the customer make intelligent decisions and system recommendations."
Making it safe, keeping customers satisfied
As with most utilities, once the functional requirements of a system were met, PECO was concerned with reliability, speed and cost.
"We were trying to find ways to operate more effectively and safely," said Pritchard, "refining how we do business to increase reliability."
Better knowledge of how the system operated led to increased safety for linemen who stored and managed circuitry more efficiently and more effectively by modifying the reclosing scheme.
On the other hand, the utility was challenged to move the workforce toward automation, pulling manual controls off of the circuit breakers. "This was a significant change in practices," said Pritchard. "But all in all it was a big safety win."
In Pritchard's opinion, however, it was increased reliability that was the most lucrative result of automating its 87 primary substations.
While Westmoreland was one of the last substations PECO renovated in the 1990s, it continues to increase reliability and speed and drive down costs through upgrades to other parts of its system. PECO's system is ever more reliable today with its ability to automatically generate information on outages from its metering system and to automatically repair short-circuits with pole-top reclosers.
"The combination is really great," Pritchard remarked. "And reliability means customer satisfaction," something that is paramount to staying competitive in the state.
"I do believe we were very progressive in what we were doing and that translates into where the utility is moving with the smart grid today," continued Pritchard. He says that the utility has made incredible strides through new communications and information technology tools; for example, through a fiber-optic network, wireless networks and having broadband capability wherever it is needed.
PECO's most current venture is the integration of customer meters into its operation management system. The utility is about 20 months into a three-year push to install advanced meters to its entire customer base. Thus far, PECO has begun the installation of the first third of the advanced meters. "This will bring two-way communications to each and every customer," Pritchard said. "All 1.8 million will then be automated."
The utility is also installing a distribution management system, which will allow PECO to receive real-time information about the distribution grid, updating a system that has been in service for 20 years.
"A new modern distribution management system will allow us advanced voltage management to help us meet energy efficiency goals and bring us meter data and distribution automation schemes all together," explained Pritchard. "It is satisfying to see this culmination of applications."
As a result of all of these upgrades and promising new technologies, in the last decade, "we've seen the first glimpse of the data tsunami," said Pritchard. "We have all this data and now we have to know what to do with it; how to process and make sense of it."
A recent New York Times article ("Age of Big Data"; Feb. 12, 2012) purports that we, including the utility industry, are in "the age of big data." Big data, says the article, is "shorthand for advancing trends in technology that open the door to a new approach to understanding the world and making decisions." The article quotes IDC, a technology research firm, as estimating that data, by volume, is growing at 50 percent each year.
Pritchard says it is important that utilities not "get blinded by the attraction of endless data."
"If you have a circuit with 1,500 customers," he explained, "you only need a handful of customers to tell you it's off-you don't need all 1,500."
With the need for advanced data analytics growing, PECO has spent a great deal of effort finding the right tools to conduct the analyses. Through its formal request-for-proposal process, the utility chooses software largely focused on specific areas of interest to the utility. "We are less interested in `one size fits all' and more biased toward specialty programs with a narrower purpose. The big ones do a lot of things, but maybe not as well," he said.
Because new software applications for managing data create new areas of learning, staff capacity must be built in these areas. Keeping staff interested in and invested in advancing PECO's system is paramount to success, insists Pritchard.
"With a multiyear project, you need dedicated people. You need staff to take ownership and become stakeholders in the process itself," he said.
Both with customers and internally, Pritchard continued, "don't overpromise. Stay grounded about what you are really capable of and take the baby steps first."
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