PSO says it performed well in winter storm despite 2,800 hours of downtime

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Documents on file with the Oklahoma Corporation Commission reveal an almost startling amount of power interruptions experienced by Public Service Company during the historic February winter storm that resulted in rolling blackouts and power losses for tens of thousands of customers.

Many of the more than 2,800 hours of interruptions and temporary shutdowns of PSO’s power units were caused by the lack of natural gas which powered the generators. Others experienced forced outages from equipment failure.

Daryll Jackson, PSO’s Vice President of Generating Assets stated in recent testimony offered in support of the utility’s $732.5 million rate hike request that the utility experienced a shortage of natural gas from natural gas providers causing approximately 34% daily average of megawatt production. He said forced outages during the storm reduced PSO’s power production 11% while maintenance outages dropped production by 12% of the daily average megawatt.

Nearly 13% of PSO’s generating units are powered by coal and 87% have natural gas-fired capacity.

Amidst the historic February storm, 77% of PSO’s forced outages were due to gas restrictions,” explained Jackson.

During the storm, PSO’s Northeastern Unit 3, which is coal-fired ran at high loads but on Feb. 16, it experienced a small derate of 5 MW for 2.5 hours “due to feed water flow issues.” On Feb. 20,the unit derated 65 MW to conduct weekly valve checks.

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“PSO’s planning and preparation was demonstrated through Northeastern Unit 3’s ability to achieve near full capacity throughout the cold weather event,” stated Jackson. “Even with all the preparation and planning, and in recognition of the serious natural of this event, an “all hands on deck” effort was sustained throughout the period of most extreme conditions.”

But a review of the other issues encountered by the utility’s power generating units offered a long list of issues. The company’s Northeastern Unit 2 was undergoing a maintenance outage from Jan, 25 to March 1 to manage asbestos abatement and re-insulation on several sections of the steam piping under the unit’s turbine. The maintenance started before the storm and the unit could not be returned quickly enough to make it available at the time.

Here is the list of other unit failures and their times of being unable to produce power:

  • Southwestern Power Station Unit 1 experienced a forced outage on Feb 9 “due to mechanical failure of the $7 bearing seal” that lasted 383 hours. Jackson testified the outage event was due to an equipment failure “not associated with cold weather” and “could not have been reasonably foreseen ahead of the weather event.”
  • Southwestern Unit 2 experienced a derating due to “gas restrictions starting on Feb. 13 lasting 169.7 hours.
  • Unit 2 was also forced off line for 59.3 hours due to fuel curtailment beginning Feb. 20.
  • Southwestern Unit 3 was derated due to natural gas restriction starting Feb. 13 lasting 169.7 hours.
  • Unit 3 was forced off line due to fuel curtailments for 35.3 hours beginning Feb. 20.
  • Southwestern Units 4 and 5 experienced outages due to natural gas restrictions starting Feb. 13 lasting 172 hours.
  • Comanche Plant Unit 1 was forced off line while still in startup on Feb. 9 due to a hydraulic control issue on the steam turbine and the outage lasted approximately 5 hours and “was not weather related.”
  • On February 12, all units experienced derating lasting just under an hour–outage due to the gas company regulator being slammed shut.
  • Unit 1 was forced off line just before midnight Feb. 14 “due to ice blockage at the cooling water intake structure.” Heavy equipment was brought on site to help clear the ice blockage. As the unit was being restarted, gas turbine 1G2 tripped off due to a mechanical problem with a feedwater control value. “This event was not weather related; however, repair parts had to be fabricated off site and 1G2 remained in forced outage for the duration of the winter event.” PSO stated that although load limited due to the 1G2 failure, 1G1 and 1S1 were restarted in 1X1 configuration for a total outage duration of approximately 17.4 hours.
  • Feb. 16 Unit 1 was forced off due to a steam pressure control issue caused by an errant signal from a frozen sensing line on the disable 1G2 steam generator. Outage duration was approximately 17.8 hours.
  • Unit 1 was also derated for 2.5 hours on Feb. 12-13 “due to fuel curtailments.
  • Unit 1 was forced off line 37.3 hours due to fuel curtailments beginning Feb. 20.
  • Riverside Plant Units 1 & 2 experienced a startup failure Feb. 10 due to an Auxiliary Boiler FD Fan bearing failure that lasted 54 hours in duration.
  • Riverside Unit 1 became unavailable due to gas restriction on Feb. 12 and the outage lasted 302 hours.
  • Riverside Unit 2 experienced gas restriction Feb. 10 lasting 3.5 hours.
  • Riverside Unit 2 experienced another gas restriction on Feb. 12 that lasted 302 hours.
  • Riverside Units 3 & 4 experienced outages lasting 172.3 hours on Feb. 13 due to gas restriction.
  • Weleetka Plant’s Unit 4 experienced a startup failure Feb. 10 “due to generator breaker failure” that caused an outage lasting 51 hours. PSO said the failure was due to the mechanical design of the breaker and was “not weather related and could not have been reasonably foreseen.”
  • Weleetka’s Unit 5 experienced a forced outage due to fuel vent valve failure that lasted 3 hours in duration on Feb. 10. The event was not weather related.
  • Weleetka’s Unit 4 experienced an outage due to lack of natural gas starting Feb. 14 lasting 192 hours.
  • Weleetka’s Unit 5 experienced n outage due to natural gas restrictions starting Feb. 13 lasting 207 hours.
  • Tulsa Plant’s Unit 4 experienced a forced outage starting Feb. 15 “due to water chemistry issues” that lasted 43.3 hours. It was not weather related.
  • Tulsa Plant’s Unit 4 experienced several deratings on Feb. 15 “due to a frozen attemperator line” totaling 31.6 hours.
  • Tulsa Plant’s Unit 4 experienced intermittent deratings due to natural gas restrictions Feb. 13 lasting 38.5 hours.
  • Tulsa Plant’s Unit 4 experienced deratings Feb. 17 lasting 48.7 hours due to fuel curtailments.
  • Tulsa Plant’s Unit 2 experienced forced outages lasting 58.2 hours on Feb. 15 “due to feedwater control issues caused by a frozen vent valve.”
  • Tulsa Plant’s Unit 2 experienced derating Feb. 13 “due to natural gas restrictions” lasting 43 hours.
  • Tulsa Plant’s Unit 2 was in forced outage due to fuel curtailment beginning Feb. 17 lasting 125 hours.
  • Northeastern Plant was derated 1.9 hours on Feb. 9 due to an excursion caused by a frozen transmittered.
  • Northeastern Plant unit 1A tripped Feb. 14 due to a frozen HP drum level sensing line creating a 3-hour outage.
  • Northeastern 1B suffered a 2-hour forced outage due to a startup delay caused by a frozen drum level transmitters on Feb. 19.
  • Northeastern 1 block also experienced a variety of deratings and outages due to fuel curtailments starting Feb. 15 and extending through the remainder of the winter event up to Feb. 22.
  • Northeastern Unit 1B was forced off due to fuel curtailments Feb. 16 lasting 75.3 hours. “The entire block was forced off line for 32.5 hours due to fuel curtailments beginning Feb. 20.

Add it up and PSO’s shutdowns, interruptions and deratings totaled 2,854 hours where the utility’s ability to provide power to its customers across the state was hampered.

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In Jackson’s testimony, he was asked “What was the largest contribution to PSO’s plants being unavailable during the winter storm event?”

“Natural gas restrictions had the largest impact on the availability of PSO’s generation fleet resulting in an approximate daily average of 34% MW reduction during the winter storm event,” he answered.

Just as another PSO executive offered in supporting testimony, which OK Energy Today explored earlier this week, Jackson defended the utility’s handling of the power issues and its natural gas acquisition decisions.

“Leading up to and during the 2021 weather event, PSO took reasonable actions to safely and efficiently operate its generating fleet,” he stated.

“While there were some outages that occurred, none was due to negligence on the company’s part, nor were any extended due to circumstances the company could have reasonable foreseen.”

The Corporation Commission will set a hearing to begin the process of PSO’s rate hike request. As OK Energy Today reported, the request, if approved, would increase the monthly charge of approximately $4.02 for the average residential customer.

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