Summary of February 2011 Storm
During the final weekend of January 2011, EPE was monitoring the actual weather and the forecast as is always done. The weather forecast was indicating significantly colder weather, but not as severe as ultimately occurred. Every year, EPE winterizes its generating plants prior to the beginning of winter weather. This winterization encompassed verifying that heat tracing and heat strips were properly functioning as well as making sure insulation was properly installed at its local generation facilities. Similarly, prior to winter weather, EPE verifies that equipment in its substations, the part of the transmission and distribution system most susceptible to cold temperature extremes, can withstand frigid temperatures. In addition, on January 31, 2011, prior to this severe weather event, EPE initiated its severe weather preparations, which included verifying winterization of generation and transmission and distribution (T&D) facilities; reviewing system operations plans; contacting the operator of Palo Verde to make sure the units were not experiencing any issues and to stress the need for power from the plant; reviewing availability of fuel; preparing for potential pipeline constraints; and putting employees on call as needed during the weather event. The System Operations group requested EPE’s Power Marketing and Fuels group to keep additional generation on-line, and, in response, Power Marketing made arrangements to leave on Rio Grande Unit 6, continue with the start-up of Newman Units GT-3 and GT-4, and verified the ability of Newman Unit 3 to operate on fuel oil.
During the afternoon and evening of February 1, the weather deteriorated significantly with temperatures dropping from 31 degrees at 4 p.m. to 18 degrees at 10 p.m. Temperatures remained below 18 degrees for the next 60 hours with a low temperature of 1 degree. Not only did the temperature drop to record levels and much lower than forecasted on January 31, but the wind was blowing at average speeds of 10 to 20 mph creating very low wind chills. The severe wind chills rapidly dissipated heat around key power plant components and accelerated the temperature drop of the components. As the temperature rapidly fell to subfreezing levels, the Company began experiencing freezing equipment at our generation facilities. Not only did critical water lines freeze but instrumentation which controls the generation froze as well. Due to these events, EPE lost most of its local generation over a period of 7 hours early Wednesday, which reduced its load-serving capability. EPE did have approximately 55 MW of local generation from its combustion turbine, Copper Unit 1, running during the entire time and even during the worst portion of the weather. This generation combined with purchases from nearby generation resources provided dynamic reactive voltage support that made it possible for the Company to import power, including the remote generation owned by EPE at Palo Verde in Arizona and Four Corners in New Mexico, and to maintain the system. During the next three days, February 2, 3 and part of Feb. 4, EPE struggled against Mother Nature to return more local generation to service, with limited success. Fortunately, with the exception of a short period of interruption on its non-firm HVDC interconnection with the Southwest Power Pool and an outage due to a damaged conductor on its line to Dell City, we had no transmission outages or failures.
As a result of the advance planning of the various EPE departments, and the effort and support of EPE employees and contractors as well as the cooperation of public and private organizations, businesses and individuals, EPE was able to maintain the system through a variety of purchases and by bringing in EPE’s own remotely located generation using our transmission lines. The Company received tremendous cooperation from all of our neighbors including, but not limited to Public Service Company of New Mexico (PNM), Southwestern Public Service Company (SPS), Arizona Public Service Company (APS), Tri-State Generation & Transmission, and Tucson Electric Power Company (TEP). In addition to these parties, the Western Electricity Coordinating Council, the States of New Mexico and Texas, the appropriate counties and all of our cities quickly mobilized when requested to assist EPE and our customers. Working through the various emergency management systems and the media, we were able to communicate with the various constituencies. When it became apparent that the Company’s local generation would not be quickly returned to service, we first curtailed our interruptible customers. In addition, between the peak load hours of 7 a.m. to 12 p.m. and 6 p.m. to 9 p.m. on February 2nd, 5:30 p.m. to 10:30 p.m. on February 3rd, and 6:30 a.m. to 12 p.m. on February 4th, the Company executed controlled load shedding to help protect the health and safety of our customers by preserving the integrity of the system and avoiding the very real risk of an entire system collapse. This load shedding was done on a non-discriminatory basis across the entire system in both New Mexico and Texas with the exception of those circuits containing critical customers (e.g., hospitals, 911, etc.).
On the day of February 4, EPE was able to return 300 MWs of generation to service and eliminate any load shedding. On February 5, EPE was able to allow interruptible customers to return to the system, and all interruptible customers were allowed to return to their normal operations by February 6.
Based upon the information known at this time, the phenomenally cold weather (60 hours below 18 degrees Fahrenheit in El Paso) and severe wind chills negatively impacted a generation fleet that is primarily designed to withstand excruciating summer temperatures, and not near zero degree Fahrenheit during the winter. It appears this weather event was the worst in at least 45 years and maybe longer. EPE’s neighbor to the south, the Comisión Federal de Electricidad (CFE) experienced similar difficulties with its generation in both Juarez and Chihuahua City.
Conclusion
During the days of February 2 to February 4, EPE was challenged by record-breaking cold temperatures. EPE had planned and prepared for the forecasted weather, and continued to do so as the arctic cold approached, but unfortunately EPE’s system was simply not designed to withstand such extremely cold and sustained temperatures. When the emergency developed, EPE followed its Emergency Operations Plan and reasonably managed its available resources as best it could. EPE’s employees put in many long hours, including those employees who were in the field working in the bitter cold throughout the period, in an effort to maintain and restore service. While the emergency event was not painless because many of EPE’s customers experienced controlled outages, EPE was nevertheless successful through the diligent efforts of its employees in managing its available resources and preventing a much worse situation from developing, such as a system blackout.