Keeping the lights on
IID System Operation Center oversees flow of power to about 150,000 customers
EL CENTRO — With about 150,000 customers in a service area spanning about 6,000 square miles, the operators in the Imperial Irrigation District’s System Operation Center have the constant task of ensuring electricity is available to power air-conditioners, refrigerators and hospital medical equipment.
The SOC — housed at an undisclosed location near El Centro due to security concerns in a post9/11 world — is staffed by a team of about three operators and one electrical engineer around the clock, year round.
“Essentially this is how IID keeps the lights on,” Justin Butler, IID superintendent general of transmission and generation dispatch, told Imperial Valley Press during a private tour this week of the highly secured facility.
“This is where we monitor our entire electrical grid. We have the room here, and right next to us is the distribution center and that is where they monitor the feeds going to their customers. We typically have three people on shift. We have an operator that handles the generation — so he is balancing generation and load. We have another operator, the transmission operator. He is monitoring the transmission lines — the big power lines you see everywhere. And then, you have the shift supervisor, and he is maintaining a bird’s eye view. They are monitoring the power going to over 150,000 customers and I believe over 6,000 square miles.”
The operators each sit at desks with several computer monitors listing real time information from the energy management system. IVP was prohibited from photographing the highly sensitive information due to security concerns.
“This is what the operators use to monitor the grid,” Butler said. “This is actually the main tool. This shows megawatt flows and different aspects of the electrical grid.”
One of the monitors shows all IID electrical installations in Imperial and Riverside counties, as well as surrounding installations in Arizona and to the west toward San Diego. Two major transmission lines run near or through IID territory. The first, which runs in an east-west direction near Interstate 8, originates from the North Gila Substation near Yuma. The second major transmission line also runs in an east-west direction near Interstate 10, and originates at the Palo Verde Nuclear Generating Station near Tonopah, Ariz.
“The transmission line, think of it as a highway,” Butler said. “Well, these are major highways and we are in the middle of it. We’ve got two major highways surrounding us.”
The operators, when maintaining an optimal load on the local electrical grid — there can neither be too much nor too little at any given time — choose when to tap these major lines for energy or when to send energy generated at local geothermal, solar, hydroelectric or natural gas plants into the surrounding system, Butler said.
Forecasting electrical need
The level of electricity on the grid varies from month to month, with lows in the winter and highs in the summer due to usage of air-conditioning units. The peak load so far this year was 1067 megawatts on July 24, with an average peak load in January of only 353 megawatts, according to IID officials.
Variance also occurs from day to day depending on weather considerations, so it is up to the operators to make minute-by-minute corrections to keep the system running efficiently. They are aided by an electrical engineer who projects conditions a day in advance to give the operators an idea of what may be heading their way.
“As an engineer, we support [the operators] with our real-time contingency analysis,” Ismael Gomez, an operations electrical engineer who has worked at the SOC for the past three years, said during the tour. “We will let them know what they can expect to see so it won’t catch them as a surprise.” Gomez and his fellow engineers will run offline models to study power outages or other issues potentially facing the operators, he said.
“What we do is we grab those values, and we simulate for peak hour. We simulate any outages and any load and generation dispatch, and we will let them know for the next day, for this hour … there might be these overloads. That is extra to what they see on the real-time contingency analysis. We will give them a document as to what we saw the day before, and this is what they are seeing today.”
Technological changes
A massive power outage that knocked out electricity to 7 million people in the Southwest, including Imperial County and parts of Mexico on Sept. 8, 2011, has led to a dramatic change in the way the IID operators conduct business, said Matt Smelser, IID assistant manager of the energy department in charge of system operations.
During the 2011 outage, an APS employee mistakenly tripped off the North Gila-Hassayampa 500-kilovolt transmission line that runs from Phoenix to Yuma, which caused a rippling effect that led to the loss of power for up to 12 hours in Arizona, Southern California and Mexico’s Baja California.
At the time of the outage, “we were very reactive, and now we are proactive,” Smelser said. “The tools we have — real-time contingency analysis — we see all this coming. At the time, we were in the infancy with that RTCA. We weren’t using it to the potential it is now. We didn’t have all these engineers on staff who have made huge improvements to the system. Situational awareness is the biggest thing that has changed.”
Power outages
When power outages do occur, it is up to the distribution operating center located next to the SOC to coordinate repairs
“We split it into two operators,” Butler said. “There is one operator who is watching the whole Imperial Valley area and then you have a second operator who is watching the whole La Quinta Coachella Valley area. There is a lot going on, especially when the power goes out. They work very closely with the call center, so as calls are coming in … to the call center” from customers reporting power outages “then the call center relays that information here and they look it up. They work with field personnel, trouble shooters … and then they go restore the power.”
Butler said that the employees at both the SOC and DOC are focused solely on ensuring IID customers have the power they need on demand.
“The AC is still blowing, the refrigerator is still going, so we need to make sure we can meet those needs,” he said.