Case Study : New Jersey’s Atlantic City Electric $37.4m distribution automation project

Atlantic City Electric's $37.4m DA project is set to help customers conserve energy. Part of that plan includes deploying 25,000 power demand-limiting devices, intelligent grid sensors, distribution automation technology and other grid communication infrastructure.

 

A rough estimate for residential, commercial, and industrial worldwide consumption of air conditioning is at the very least one trillion kilowatt-hours of electricity per annum, according to research conducted by Stan Cox, a senior scientist at the US non-profit Land Institute in Salina, Kansas and author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World (and Finding New Ways To Get Through the Summer).

“Vehicle air conditioners in the United States alone use 7 to 10 billion gallons of gasoline annually. And thanks largely to demand in warmer regions, it is possible that world consumption of energy for cooling could explode tenfold by 2050, giving climate change an unwelcome dose of extra momentum,” writes Cox in article he penned earlier this summer for Yale Environment 360, a publication of the Yale School of Forestry & Environmental Studies.

With greater demand for air conditioning across the globe utilities and grid operators have to consider how they can function with this growing, let’s face it, luxury product, which is often run at peak hours. One place that is making change to account for hotter summers and increased air conditioning is the US state of New Jersey. The state experienced record high temperatures this past summer, but in the future many residents in the state will have the ability to lower their utility bills while still staying cool. 

Conserving energy

That’s because Atlantic City Electric, a division of Pepco Holdings, is in the midst of a $37.4m project designed to modernize the electric distribution system in southern New Jersey and help customers conserve energy.

Chief among that mission is the deployment of approximately 25,000 power demand-limiting devices, intelligent grid sensors, distribution automation technology and other grid communication infrastructure to enhance reliability and optimize grid operation.

By rolling out demand response technologies, customers are given the ability to have their air conditioners or thermostats cycled on and off at peak usage times, helping to reduce overall consumption, reduce energy costs and preserve the integrity of the electric system during critical load consumption periods. The direct load control devices provide financial incentives for customers for allowing ACE to cycle air-conditioners or control thermostats during peak periods. 

Distribution automation technology will also improve the reliability of the electric system and enable Atlantic City Electric to better manage the flow of power through the lines and restore service more quickly and safely.

“The idea behind the distribution automation work is to reduce the amount of impact that permanent outages have on our customers,” says Joe LoPorto, Manager, Special Projects & Distribution Automation Program Manager for Pepco Holdings.

Distribution automation devices, which include feeder monitors, equipment condition monitors, and automated feeder switches will improve the reliability and power quality of the distribution system. These systems also reduce operation and maintenance costs as well as distribution line losses.

Automatic Sectionalizing and Restoration Schemes 

Utilising $18.7m in federal stimulus funds that the utility was awarded by the Department of Energy (DOE), Atlantic City Electric is installing automatic sectionalizing and restoration schemes (ASR) for 27 feeders through its distribution system. 

The utility spent most of 2010 and 2011 upgrading and installing necessary infrastructure, and in recent weeks placed the first three automated feeders into service. The utility will activate 10 more by the end of 2012, with full deployment expected by the end of next year. Pepco has similar projects underway in Maryland and in Washington, D.C.

The project involves taking a feeder that serves 2,000 customers and segmenting it into four parts with reclosures and creating ties with other feeders in between those reclosures. The programme will add communications to those field devices, mostly reclosures, and also add smart devices at the substation, including smart relays and advanced distribution remote terminal units, and an ASR control programme to tie the system together.

When the DA system receives word of a permanent fault on a feeder, it is able to determine which devices saw the fault and which did not. The system then separates the voltage segment by opening the devices on either side of the fault and closing other feeders to restore customers that were not impacted by the fault.

“So for a feeder that normally carries 2,000 customers and suffers a fault, normally all 2,000 would be out of service,” says LoPorto. “But in this case you can potentially reduce that number to 500 by segmenting the feeder if that fault is between the substation and the fault and the first reclosure.”

In addition to limiting the number of customers impacted by a fault caused by a storm or a car crash involving a utility pole, the technology allows the utility to restore power to un-impacted customers automatically.

Immediate benefits of distribution automation

“Normally it takes between one and two hours, but the technology allows you to do it one or two minutes,” says LoPorto. “In addition, we are able to isolate the fault so that our crews don’t need to patrol a longer length of the feeder. They know between which two devices the fault is located at so they can go there directly and get to work on the problem right away, be it a pole damaged by a fallen tree or by an automobile accident.”

Atlantic City Electric is attacking feeders that can benefit most from distribution automation. The utility has about 2,000 feeders in its system, and by improving reliability in a small percentage of them by 50 per cent, utility executives expect to see a 10 per cent improvement in its full numbers across the board.

LoPorto says that the major benefits from the distribution automation programme include improved electric service reliability and power quality, reduced operating and maintenance costs, reduced costs from equipment failures and distribution line losses, and reduced greenhouse gas and emissions.

The utility is also working to install automated capacitors to increase the voltage on a distribution circuit by providing reactive power. Capacitator banks are switched in discrete steps, either manually or in response to the voltage at the location where they are connected. 

“Eventually we want to add voltage control where you are adding communications to your load tap changers at the substation to maintain a consistent voltage profile, as well as institute conservation voltage reduction programmes,” says LoPorto.

Additional reporting by K. Steiner-Dicks

Useful link: http://www.e360.yale.edu