ERCOT: Four 345-kV lines experiencing storm-related forced outages restored

ERCOT, in an Aug. 30 report filed with the Public Utility Commission (PUC) of Texas, said that it will continue working with transmission and distribution providers as they continue repairs to damaged transmission facilities in light of Tropical Storm Harvey.

“Because current forecasts project that Tropical Storm Harvey will move to the northeast over the next few days, ERCOT does not expect any major system-level reliability or market impacts from the storm,” ERCOT said. “However, ERCOT will promptly update the commission should conditions change.”

As noted in the report, Harvey made landfall as a Category 4 hurricane near Rockport, Texas, at about 10 p.m., on Aug. 25. At landfall, the storm produced sustained winds of about 130 mph and caused significant damage in Rockport and the surrounding areas, ERCOT said, adding that the storm gradually weakened to a tropical storm by the evening of Aug. 26.

The storm has led to fatalities, according to news outlets, including the Houston Chronicle, which on Aug. 31, citing local officials, reported that almost 40 people "have died or are feared dead in the Houston area and beyond." The New York Times reported that "more than 30,000 people remained in shelters."

Information about shelters and assistance can be found at the Texas Hurricane Center webpage.

In its filing with the PUC, ERCOT said that since making landfall, the storm has produced significant rainfall throughout central and southeast Texas. The Houston metropolitan area, in particular, has received unprecedented rainfall – exceeding 50 inches in some areas as of the morning of Aug. 30 – which has caused extensive flooding, ERCOT said.

While rainfall related to Tropical Storm Harvey is expected to subside in the Houston area in the coming days, it is expected that it will take significant time for flood waters to recede, ERCOT said.

To minimize the impact of forced outages that the approaching storm was expected to cause, ERCOT said that it worked with Transmission Service Providers (TSPs) to restore or cancel as many planned outages as possible. Among other things, ERCOT said that it also activated on Aug. 25 its internal Disaster Management Team, who worked throughout the following days to ensure that ERCOT’s operations were not impacted during the storm event.

The ERCOT system has experienced a number of transmission forced outages as a result of the storm event. Since the hurricane first made landfall, six 345-kV transmission lines have experienced storm-related forced outages, but as of the morning of Aug. 30, all but two of those lines have been restored, ERCOT said. In addition, 91 138-kV circuits and 138 69-kV circuits in the areas impacted by the storm have also experienced storm-related forced outages. About 52% of the 138-kV facilities and 34% of the 69-kV facilities remained in outages as of the morning of Aug. 30, ERCOT said.

While the large majority of those outaged facilities are located in the Coastal Bend area of Texas, where the storm initially came ashore, some of those facilities are located in the Houston area and have been impacted by storm-related flooding, ERCOT said. Those outages have resulted in the disruption of service to large numbers of customers and the temporary islanding of a small part of the ERCOT system, ERCOT said, adding that it has submitted required reports concerning those events to the U.S. Department of Energy and to NERC.

ERCOT noted that as a result of certain 345-kV outages, it issued two Reliability Unit Commitment instructions to make generation available for reliability purposes. ERCOT said that on Aug. 25, it instructed one generation facility to bring additional capacity online in order to ensure sufficient resiliency in the Lower Rio Grande Valley to address any immediate impacts of the storm, and on Aug. 26, it instructed another unit in the Victoria area to provide system resiliency and voltage support.

Generation capacity has also been negatively impacted by the storm, ERCOT said, adding that as of the morning of Aug. 30, about 8,000 MW of generation is outaged and about 3,000 MW is derated due to storm-related causes. The outages are generally attributable to rain or floodwaters affecting fuel supplies, outages of transmission facilities at the generator’s point of interconnection, or the inability of plant personnel to reach the generating facility. That amount of outaged generation has been dropping, down from a maximum of more than 10,000 MW, ERCOT added.

Despite the foregoing storm-related outages, ERCOT said that it has had plenty of generation to meet total system demand and expects to have sufficient generation for the foreseeable future. System demand has been significantly less than normal since Aug. 25, and is about 15,000 to 20,000 MW lower than what is typically observed during this time of year. That is attributable largely to cooler temperatures in the region as well as the substantial number of customer outages in the areas affected by the storm, ERCOT added.

Among other things, ERCOT said that its market has continued to function as expected throughout the storm event.

Company updates

According to the Tropical Storm Harvey Event Report (Update #12) posted on the website of the DOE Office of Electricity Delivery & Energy Reliability, now Tropical Depression Harvey continues to produce heavy rain across western Louisiana, which has led to significant flooding. While Harvey is beginning to move out of the region and is forecast to weaken, it will continue to produce weather impacts through Sept. 1, according to the event report.

As of 2:30 p.m., EDT, on Aug. 31, Texas had 186,969 customer outages, representing 1.6% of customers in the state, while Louisiana had 9,116 customer outages, the event report noted.

American Electric Power’s (NYSE:AEP) AEP Texas, in an Aug. 31 statement, said that it has restored power to about two-thirds of the customers left without power as a result of Harvey. The latest outage numbers include 37,600 outages in the Aransas Pass – Rockport Area, and 19,700 outages in Corpus Christi, the company said.

Entergy’s (NYSE:ETR) Entergy Texas on Aug. 30 said that as of 12:30 p.m., more than 80,000 customers were without power – surpassing the peak outages of 41,000 experienced across the Entergy Texas region earlier in the week. The company said that its restoration workers are using air boats, high water rescue vehicles and helicopters to access areas where catastrophic flooding caused by Harvey continues its destruction in southeast Texas.

Guadalupe Valley Electric Cooperative, in a separate Aug. 30 statement, said that after five days of restoration efforts, all but 21 outages have been restored for its members, with the remaining outages to be repaired once flood waters recede.

Austin Energy on Aug. 29 said that since 9 a.m., on Aug. 26, crews have restored power to more than 59,000 customers.

The Midcontinent ISO (MISO), in a statement updated on Aug. 30, said that it issued on Aug. 30 a conservative operations alert. Conservative operations help ensure that non-impacted transmission and generating units remain available to serve the grid, MISO said, adding that conservative operations, as well as a continuing severe weather alert, are expected to be in effect through Sept. 1. MISO said that its operators are working with member utilities to manage the related outages and to maintain the reliability of the transmission grid across the South region.

The Louisiana Public Service Commission on Aug. 29 noted that the forecasted final landfall of Tropical Storm Harvey was anticipated to occur the morning of Aug. 30 in the vicinity of Cameron, La. The commission said that it encourages residents to be vigilant during the storms, including by reporting downed power lines and outages.

James Lass, general manager of distribution operations and emergency equipment of Cleco, in an Aug. 30 statement, said: “Tropical Storm Harvey made landfall near Lake Charles early this morning and is expected to cross the state before exiting the northeast corner by Thursday morning. Cleco line crews and contractor crews are currently responding to reports of scattered outages.” 

Cleco said that it has nearly 100 crews ready to respond to weather-related power outages and clear debris that may come into contact with its power lines.

According to an Aug. 31 Weather Prediction Center public advisory posted on the website of the National Oceanic and Atmospheric Administration, flooding rains continue across far eastern Texas and western Louisiana, with heavy rainfall spreading northeastward through the Lower Mississippi Valley, and into the Tennessee and Ohio Valleys, as well as the Central Appalachians over the next day or two.

About Corina Rivera-Linares 3061 Articles
Corina Rivera-Linares, chief editor for TransmissionHub, has covered the U.S. power industry for the past 15 years. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines. She can be reached at clinares@endeavorb2b.com.