No Substitute for a DEC Substation

To the everyday person, the process of using electricity to power the community might appear to be simple. A person contacts their electric utility, the utility hooks up a meter, and voila! That person has electric! However, a closer look at that process proves that safely and effectively providing power to homes and businesses within a given service area is much more complex. It includes many working parts, one of the most important being the capabilities and effectiveness of a utility’s substations. At DEC, the main goal of the employees in our substations and systems protection department is simple: maintain the substations, protect the system, and above all, keep the lights on.

Substations and system protection fall under the broad heading of engineering, with a focus on the transmission side of the power lines. The purpose of a substation is to convert the transmission voltage, which comes from a utility’s source, such as a power plant, into a lower voltage that can be processed and delivered to members through distribution lines.

When trying to understand the importance of substations to the overall functioning of the lines, substation supervisor Mark McAllister compares the Co-op’s electrical system to a body, and within that body, a substation represents both the heart and the brain.

“The heart would be the transformer. The transformers are large pieces of equipment that are transforming high voltage to lower voltage. We get the higher voltage from transmission voltage that originally comes from our interfacing utility,” McAllister says. “Then the transformer will knock that voltage down to our distribution line voltage that powers each individual house. The brains would be the actual protective relays and SCADA equipment within the substations that protect individual transformers and also the individual circuits from faults that occur on the line.”

According to manager of substations and systems protection Tony Rutherford, substations and the protective measures used to maintain DEC’s system are essential to the Co-op’s ability to provide members with quality power. Without them, the system would be forced to backfeed – draw electricity from other circuits – over an extremely long distance, which would lower the quality of the electricity being provided to members. The way the system is currently designed, each substation is responsible for a designated section of Delaware Electric’s service area.

“Substations serve as the point where a particular area is being served from that substation, so you’re going to get your best voltage and service from that substation,” Rutherford says.

Rutherford says that the goal is to ensure the circuits of the substation are delivering a balanced load to the distribution lines. Similar to backfeeding over long distances, an imbalance of load can also affect quality of power. A load imbalance can occur when there is damage to a pole, whether from a car accident or weather-related incident – anything that may require the system to backfeed and draw power from another circuit. That’s why system protection is such a necessity.

“The thing that’s just as important as the substation is system protection. We’re not just substations in this department,” Rutherford says. “We also do system protection, and basically that’s the coordination of all the circuits, making sure when a car accident or a broken pole or a storm happens that we’re isolating the affected members to the area that is impacted.”

To do that, lines are outfitted with protective relays that sense faults. According to McAllister, if a tree limb is on a line or a car damages a utility pole, protective relays will put the affected equipment offline as quickly as possible to minimize any outage effects. It’s another issue entirely if a substation goes offline.

“For the substation to be offline, individual recloser circuits see a fault and they will trip, but they’ll also re-close. They wait a small amount of time and then they try to re-close the circuit because the nature of most faults are temporary,” McAllister says. “For instance, a tree limb hits a line, it shorts out, there’s a small explosion where it hits and it knocks the limb back off. So you have a trip, you have a re-close, and you stay closed. But if the limb’s a big one, and it’s sitting on that line for an extended period of time, you’ll have several re-close attempts, and if it can’t re-close because there is a maintained fault, it will open that circuit.”

The work of the substations and systems protection department is that of constant motion, first with the work of designing how the substations will interact with the transmission and distribution lines, analyzing those designs to try to predict the best way to manage loads when issues arise, then back to the drawing board to improve parts of the system that could be better. If that pace wasn’t challenging enough, the size of DEC’s system is. With 27 substations spread out across Kent and Sussex counties, it can be challenging to keep up.

“We have a dynamic system,” Rutherford says. “Load is always changing on our distribution circuits. People are always adding load, either through new developments or through some type of commercial application.”

The additional load presents another challenge – preparing for it. To keep up with member growth, the system must be able to support any and all new distribution.

“We have such rapid growth here that it has been a challenge in the past, making sure that we’re prepared to meet the need,” Rutherford says. “And a lot of that goes back to backfeeding. Can we meet the needs? We can meet the needs in a forward feed, but can we meet these needs going backwards?”

As the system continues to grow and change, so do the substations themselves. If maintained properly, the average lifespan of a substation’s transformer is about 50 years. Our systems protection technology continues to modernize to increase the quality of the system’s performance.

“The protection relay equipment has become more sophisticated because of improvements in electronics and microprocessor equipment, so we are replacing old protective relays with newer ones,” McAllister says. “The older ones are starting to exhibit some problems, and also, they just can’t do all the functions that we would like them to do, that the newer ones can do.”

According to Rutherford, the new relays being used on the system also allow for the communication of equipment in the field back to headquarters through the use of SCADA technology.

“SCADA plays a huge part in analyzing what’s going on in the substations, but also what is going on with our lines, too. We basically have the ability to communicate with all of the equipment to make sure everything is going good,” Rutherford says. “Between the new equipment and the capability to communicate to the equipment, that’s a big deal for us.”

Though it can be a demanding job, Rutherford says the challenges are worth it to be able to see all the planning come together in the end result.

“My favorite part of the job is when coordination actually works,” Rutherford says. “Design is just design, it’s what we think is going to happen. But this system is a beast. It’s dynamic, and it’s ever changing. Actually seeing something that you worked on from paper to installation come to fruition and come to life, that’s a pretty good feeling.”

For McAllister, who has worked with substations for over 40 years, the best part is the problem-solving aspect.

“In my background, troubleshooting of power systems equipment and circuitry was one of my favorite activities,” McAllister says. “Now as a supervisor of technical staff, I can help with special projects that involve investigation and repair of equipment and system circuitry.”

The idea of providing efficient, reliable power to communities without substations being a cornerstone of the process isn’t only unthinkable, it would be impossible. Through evolving technology, the substations and systems protection department monitors the pulse point of the Co-op – it’s lines – to ensure the quality of electricity reaching our members always meets the DEC standard.