ERCOT GRID BLACKOUT PREVENTION AND EMERGENCY PROCEDURES
It takes more than a simple flip of a switch to get things back up and running in the event of a power outage. Dan Woodfin, Director of System Operations for the Electric Reliability Council of Texas, explains below.
WHAT HAPPENS WHEN THE LIGHTS GO OUT?
Electricity is the lifeblood of modern society. Plentiful, affordable power sustains us at all levels, from running businesses and refineries, to the electricity you use in your home for cooking and cooling. We all depend on this unique form of energy which, unlike gas or water, cannot be efficiently stored in large quantities. It must be produced, transported and delivered instantaneously each moment of the day.
The widespread blackout in the Northeast United States in August 2003 and the cascading blackout in Southern California-Arizona last September left thousands without power – some for several days. Those events outside of Texas heightened public awareness of the vulnerability of electric grids and the impact of a massive blackout on communications, transportation and water systems, as well as individuals.
ERCOT is the organization entrusted to keep electric power flowing to more than 23 million Texans – about 85 percent of the state. We have highly skilled professionals who monitor the bulk transmission grid 24/7 to keep the generation supply and demand balanced at all times. Our operators use sophisticated models and programs to address unexpected plant outages and temperature extremes.
WHAT DOES ERCOT DO TO PREVENT A MAJOR GRID EVENT?
ERCOT’s job is to take appropriate steps to minimize the probability of a significant grid event happening and be ready to respond if it does. Every day, our system runs a real-time contingency analysis every five minutes, and normal operation is maintained within first-contingency limits. This means that if any piece of equipment fails, no other lines would be overloaded. Our operators can re-dispatch generation to keep within safe limits. And when power runs short of the load, operators can deploy the reserves that they buy every day as “insurance” in case of a major unexpected outage or higher-than-forecast electricity usage.
If the reserves drop below safe limits, ERCOT operators begin emergency procedures – a progressive series of steps that allow the system operators to bring on additional generation from other grids and initiate load-management programs – large customers who volunteer and are paid to be curtailed during emergencies. ERCOT, along with the Public Utility Commission and the region’s market participants, will also ask the public to conserve electricity during the peak demand period – 4 to 7 p.m. – during the summer.
These steps will often alleviate a temporary capacity shortage. However, a significant disturbance can occur on any electric grid, and ERCOT must be prepared for grid emergencies regardless of cause – whether it’s a weather event or a physical or cyber event causing multiple failures of power plants or transmission lines. If necessary, operators can instruct the utilities in the state to reduce the load on the grid by conducting temporary outages at the local distribution level. These temporary, rotating outages are intended to preserve the integrity of the grid as a whole and to avoid more serious problems. Rotating outages are rare – ERCOT has implemented rolling outages on the state grid only three times: December 22, 1989, April 17, 2006 and February 2, 2011.
Fortunately, these controlled, rolling outages helped ERCOT avoid an uncontrolled, cascading blackout like the Northeast blackout, which is much more severe than the temporary outages that rotate to different neighborhoods after 15-30 minutes. A cascading blackout is when plants and power lines trip off in quick succession causing a massive blackout. Texas has never experienced a statewide blackout, but ERCOT has procedures in place to restore the grid in case of a major grid failure.
WHAT WOULD IT TAKE TO RECOVER FROM A MAJOR GRID FAILURE?
A region-wide blackout can take days to recover from because of the difficulty of reconnecting and synchronizing the grid’s 500-plus power plants and 40,500 miles of high-voltage transmission. That’s why ERCOT has extreme procedures in place to avoid such an event. However, since it is impossible to completely protect against the type of blackout events that have occurred in other regions, ERCOT has “black start” procedures and black start units under contract to assist in restoring the system to a normal state as quickly as possible if such an event were to occur.
HOW DOES ERCOT PREPARE FOR A MAJOR GRID FAILURE?
ERCOT conducts annual simulator-based “black-start” training courses to provide training for transmission and generation operators on restoration procedures in the event of a system-wide blackout. The control center simulator at ERCOT’s Taylor facility allows operators to receive hands-on training without any impact to the grid. The system replicates the ERCOT control center computer systems and also includes a power system model to mimic the behavior of power systems and a subsystem to create events under various operating conditions.
ERCOT has contracted with specific black-start units to be available to assist in restoring the system to a normal state as quickly as possible. Black-start units must be able to start up on their own without support from the grid and then be able to pick up their own internal load.
During the simulator training, the transmission operators are required to build stable “islands” starting with these black-start units toward the goal of reaching synchronization points with other neighboring black-start islands. The generation operators start and control their resources as necessary. When the islands are ready to be synchronized, the transmission operators work with ERCOT’s system operators who control the restoration and coordinate the synchronization and frequency control until the entire system is reconnected.
WHAT CAN WE IN EMERGENCY MANAGEMENT/GOVERNMENT DO TO HELP IN THE EVENT OF A GRID EMERGENCY?
If ERCOT initiates emergency procedures, we contact the State Operations Center immediately to help us get the word out to city and county officials, law enforcement and first responders. We also contact Legislative officials and the governor’s office to assist us in getting information out to the public about the need for energy conservation during a power shortage.
WHAT CAN CONSUMERS DO TO HELP DURING A POWER SHORTAGE OR TO PREPARE FOR A GRID EVENT?
The most important way that the public can help during a power shortage is to reduce their electricity use during the peak demand period in the summer by adjusting their thermostat a few degrees higher and delaying the use of electric appliances such as washers and dryers until after 7 pm.
Preparing for a major grid failure would be similar to whatever steps a family might take in preparation for a major hurricane, which might leave them without power for several days.
-- Clarisa Marcee, TDEM State & Federal Plans Unit
Front Page Photo: ERCOT Taylor Control Room. Photo courtesy of ERCOT.