Katrina Poses Extreme Challenges for Power Engineers

by Greg Hill

IEEE-USA Today's Engineer asked two electric power engineers experienced with storm damage and service restoration for their thoughts on the devastating effects of Hurricane Katrina, and what power engineers are doing, and will need to do, to restore electric service in affected areas, returning Gulf Coast residents to some semblance of normalcy.

With flood waters expected to remain for 30 days or more in New Orleans, drying out power plants and substations and repairing damage inflicted by the brackish waters will be priority number one for local utilities. The recovery process is expected to be slow across the entire region, and power has been restored to only a small fraction of consumers. According to its online emergency center, Entergy Corporation continues to assess damages, and, as of 2 September, it had restored power to 363,000 of its customers in Mississippi and Louisiana — but approximately 728,000 remained without electrical service. Crews are working to restore power to critical infrastructure — including hospitals and water treatment plants — before they will be able to turn their efforts toward restoring residential service.

As the lead federal agency responsible for energy assurance, the U.S. Department of Energy's Office of Electricity, Delivery and Energy Reliability (OE) is working with the Federal Emergency Management Agency and state and local governments to respond to Hurricane Katrina's aftermath. OE is posting on their Web site periodic situation reports outlining progress and challenges. For more, visit: www.ea.doe.gov/hurricanes.html.

About the Experts

Harold Adams is director of electric market policy at Dominion Resources Services in Glen Allen, Va. He has served as manager of Dominion Virginia Power's control center and later managed the company's storm center. Both roles involved emergency planning for hurricanes and other service disruptions. He is a member of IEEE-USA's Energy Policy Committee and past chair of the IEEE Richmond Section.

Jack Casazza is president of the American Education Institute in Springfield, Va. He was formerly a corporate officer for PSE&G and an executive with major consulting firms. He is versed in the technical, institutional and regulatory aspects of energy systems, and has been involved in system restorations after major hurricanes and ice storms. Casazza has qualified to work as a utility lineman. He is an IEEE Life Fellow, and a member and former chair of IEEE-USA's Energy Policy Committee.

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TE: What's it like right now for the power engineers at the utility companies in New Orleans and along the Gulf Coast?

Adams: Situations like this present a major challenge. Obviously, the volume of work is very high and there is usually limited information available during the initial stages of restoration, making it difficult to understand the full scope of the job at hand, and to set priorities.

Casazza: Engineers are trying to do their job. They have to get out there, they have to supervise and they have to coordinate.

Almost every company, every organization has a written plan of how they’re going to handle all kinds of emergencies. Engineers prepare those in advance; they try to anticipate what’s going to happen and how it should be handled.

The first thing they have to do is assess the situation. What’s the situation with the power plants and the substations? You have to take a look at your transmission lines. Part of the question of deciding how to proceed is can I get crews in? Where are the roads open so I can get people in? Do I have to fly these people in by helicopter to do this work? Do I have to get them in by boat? Do I need help from other companies?

In many cases, people who are in the engineering department, the planning department, maybe even in the communications department, if they have a practical background, [they] will be given assignments in the field. They’ll be asked to go out and take a look at how deep the water is; to determine if we can reenergize some transformers, if we can get an energized transmission line in? What spare parts will be needed? That’s the kind of thing they're doing and reporting back. Almost everybody who has some technical expertise will be given some kind of an assignment in this kind of situation.

The problem down there with the hurricane is the difficulty with transportation. If you have a tornado, the roads are usually open, or at least there’s a way to get around the fallen things. With this kind of thing, getting people in there is going to be very, very difficult. But you have to get people in to take a look at it with their own eyes, so they can come back and say, “here’s what I think can be done.” In many cases, there just aren’t enough people to do this. You have to use everybody you have available in the office. And get outside help.

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TE: What roles do power engineers assume when a major storm or other natural disaster strikes, and in the aftermath?

Adams: Power engineers take on a variety of roles, depending on their specific skills and experience. In regional power control centers, engineers must understand the condition of the system and establish restoration priorities and the sequence for switching to bring the transmission system back into service. This may involve both operating judgment and power system modeling to assure the system remains in a stable state as components are restored.

In local control centers, the work is similar to the regional centers, but focused on the distribution system. No distribution service can be established until transmission is restored to the distribution substations, so the local centers must work with the regional center. Once transmission is established, local engineers and operating personnel can assess damage and establish restoration priorities. The highest priority generally goes to public facilities such as hospitals and water treatment facilities, but the exact sequence will depend upon the extent of damage to both the electric system and customer equipment. Obviously, not much can happen electrically until water recedes. There's really not much point restoring power early on to areas where customers can't use it, so work needs to be coordinated.

Some power engineers in either type of control center may help provide information to media or regulators to make sure the public is informed of restoration progress.

Power engineers in planning departments may need to perform analysis related to restoration or reconstruction of damaged facilities. In some cases, the system may be reconfigured by installing temporary facilities, and these often need to be analyzed.

And power engineers are often called upon to assess the condition of specific pieces of equipment that may have been damaged or to perform design or project management for the restoration.

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TE: What kind of challenges does a hurricane like Katrina pose for the generating plants and the regional/national electric grid, as well as localized electrical service?

Adams: Generating plants typically operate under the direction of regional control centers. Their main priority in an emergency is to make sure that they are in a condition to run if called upon. Because the transmission system may have been damaged and the normal customer load pattern disrupted, flexibility of operation is a key. The main challenge for a plant, then, is to assess and repair any damage that may have occurred, and work with the regional control center to support restoration of service. Plants may also experience disruption of fuel supply, so this could also be a problem at some plants.

Under normal conditions, the regional electric grid is stressed most during periods of high loads. After damage from a hurricane, load is lost, so the problems are different. Individual pieces of the network have been damaged and rendered inoperable. The challenge at this time is to figure out what pieces are left, put them back together in a sequence that restores as much power as possible, as fast as possible, and that remains stable in operation as conditions change and load is added back to the system.

The challenge to localized service is similar, but there is more detailed focus on the particular restoration priorities for local customers and government.

In all of these cases, manpower and equipment logistics often present a major challenge. The situation with Katrina looks unprecedented in that respect.

Casazza: As far as the generating plants go, there can be a lot of damage in the switch yard. Flying debris can short out pieces of the bus, causing it to trip out. And you can’t restore anything until you get that cleaned up. Then you’ve got the problem with the water. If the water gets too high in a power plant, you’ve got to shut it down. The same thing is true with a substation. You’ve got to shut it down before it flashes over. The water will cause it to flash over and do a lot more damage. The arc will burn things up. So you shut it down before that happens; and then after the water goes back, you try to dry it out and restore it.

The grid is probably not existing too much down there. I don’t know how many transmission lines they’ve lost, but I know they’ve lost a lot. This is what the people in the operating center, the dispatch center, have to be assessing. They have to be assessing it in each of the of the power pool headquarters, the regional grids, the Regional Transmission Organizations and Independent System Operators — they have to be assessing what the situation is.

The first questions that come up in the dispatch center are: how much generation have we lost? And how much load (consumers) have we lost? If you’ve lost a lot more generation than consumers, you probably want to get the generation started up again and operating and then reconnected to the system with the transmission lines.

With generating plants and the national grid, that’s all decided in the control center, based on information from outside. With individual distribution lines — the lines that run up and down the streets, that feed into your house and mine — there’s a tremendous amount of work there that has to be done.

The first phase is collecting all of this information, looking at what you can do and how best to do it? It’s judgment. You may have an advanced battle plan, but you still have to have a lot of judgment to do it. It’s nobody else but the engineers, who have worked in this stuff day in and day out, who have the judgment to do this.

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TE: What can be done to make electrical transmission and distribution systems more robust and resilient to storms such as Katrina?

Adams: The robustness of electrical systems under severe weather conditions typically is a function of several key factors:

1. Design Criteria — Power lines and other facilities must be designed to withstand the wind loads expected in a particular geographic area. The National Electric Safety Code includes such construction standards, but in some cases more extreme design cases are considered by engineers. Designing for more extreme weather adds cost, but having strong designs can be critical.

2. Good Maintenance — Once properly designed facilities are in place, they must be maintained in a way that preserves their physical and electrical integrity over the life of the equipment. Poorly maintained equipment is generally subject to more damage from extreme conditions, and is less reliable under stress as service is being restored.

3. Vegetation Management — Much of the damage during major storms is due to trees or limbs falling into power lines. While it is unreasonable to expect that all trees can be kept out of power lines during a hurricane, damage can be minimized if a well organized tree trimming program is maintained. No amount of tree trimming can protect against storm surge or flying debris along the coast with a storm like Katrina, but it's also important further inland to minimize damage from the high winds.

4. Equipment Redundancy — Using networked circuit arrangements and ensuring spare equipment is available can help to minimize restoration times. The specific plans that are reliable and cost effective at each utility will depend upon local conditions and requirements. Engineers usually consider this in the planning process.

Even with all these steps, it's very difficult to protect systems fully against storm surge, flooding and flying debris. Service disruption is almost inevitable under such extreme conditions, but taking the steps above can help also make it easier to get the lights back on.

Casazza: One of the things that is essential is planning a transmission system — deciding what lines should be built and what lines should not be built. In designing a power system, the transmission engineer should have in the back of his or her mind: "There are going to be emergencies of this type; and I’ve got to build a system not just for normal conditions, but I’ve got to build a system that can cope with emergencies."

I went through an exercise such as this when I worked in New Jersey, at Public Service Electric & Gas (PSE&G). It was a major wind and ice storm around Thanksgiving, which took down a lot of the distribution circuits in New Jersey. People were without service for as much as a week. The net effect of this was that the company said: “We want to embark on a program to storm-proof all of our distribution circuits. So, no matter what happens, we can restore service in two days.” So, they went around and rebuilt a lot of their circuits, where they put in a steel messenger to hold up the phased wires, using special types of spacer cable. They rebuilt a lot of it, and it cost many millions of dollars. And it was somewhat effective. They’ve had some other problems with it, but there are some techniques for storm-proofing distribution circuits.

As far as storm-proofing the transmission circuits is concerned, since the vast bulk of them have to be overhead, there’s really not much you can do. There are some ways to put dampers on them so they don’t bounce as much in a wind. But you really cannot storm-proof the system completely. No matter what you do, the electric power system is going to be subject to interruptions — major interruptions.

At one point, the Rockefeller Commission did a famous study about putting all of distribution circuits underground. And they came back saying it’s just not economically feasible. Some people still argue for putting them underground. But even underground, with the kind of flooding you’ve got [in New Orleans], you could have problems.

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TE: In a storm or disaster situation, any safety tips for individuals dealing with electrical outages and downed services?

Adams: Assume that all downed wires are energized. Don't touch or go near them. Call the utility or notify police or fire if you see downed wires.

Be patient. Things are bad enough, don't make them worse. Impatience sometimes leads people to jury-rig electrical connections or other equipment. These arrangements can often be dangerous. Don't do it. Rely on the professionals to get service restored.

There may have already been deaths from carbon monoxide from running generators, so if you're going to use a generator, make sure there's ventilation and no wiring or connections in the high water.

Casazza: Don’t touch downed wires. Never touch anything. Leave it up to the utility to take a look at it. If you see a wire draped over a bush, don’t go over and take it off the bush. If you see something else lying on the ground, a piece of equipment, don’t touch it. Leave it alone. Call the utility to come out and take care of it.

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Greg Hill is managing editors of Today's Engineer online, and can be reach at g.hill@ieee.org.