TLRs
LEW HANES: What would you do if you had a TLR?
BILL MELTON: A TLR is a process which advances in steps according to system conditions. The first step alerts you to a particular problem. As the problem increases in severity, more drastic measures are required. You get to a certain point in the process where you know that with the next step you are going to lose some or all of the expected power across the interface. So you have got to keep in the back of your mind that if they take that extra step and start cutting or curtailing the schedules that you're receiving across that interface, you will have to be able to cover what is lost.
LEW HANES: How much of an advance warning would you have before the TLR would go into effect?
BILL MELTON: You should get at least thirty minutes, but as soon as practical is recommended. Most TLR's are called at 20 – 25 minutes past the hour, and you've got to the top of the hour, which may give you about thirty minutes.
LEW HANES: In that situation, how do you get enough power to meet your needs?
BILL MELTON: You have to have considered that possibility in your planning process. You may be buying 200 megawatts, but you know that in the next hour it might not be available. Therefore, you have to have those megawatts in your reserves, or have a plan to be able to recover from that 200-megawatt loss in some way.
The plan might be to use combustion turbines. Since it can take 20 to 30 minutes to get some of your combustion turbines on line, it is important to have some advance notice of schedule curtailment or losses so that you have time to dispatch this reserve.
You have to keep in mind how much Alabama Power and Georgia Power, which have hydro resources, can actually load out of schedule to help you out in a situation. They may be able to load all that is needed for a short period of time, but not for long with the drought situation we've experienced for the last few years. We may be able to load x amount of megawatts for x amount of minutes or hours. Knowing your resource availability like this is part of the planning process which allows you to prepare for all situations.
The resources that we have available for load balancing include the fossil reserves, combined cycle reserves, hydro reserves, and combustion turbines. These available megawatt reserves are displayed in EMS. We do not carry reserves on nuclear. These reserves are in our control area, which includes all of the resources of the Southern Company utilities.
Sometimes we have internal line loading problems. This means that
we load generation outside of schedules or economic dispatch to solve the
overlo