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Luminant To Pay $1.1 Million Under Settlement With Texas PUC Staff

August 20, 2018

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Copyright 2010-17 EnergyChoiceMatters.com
Reporting by Paul Ring • ring@energychoicematters.com

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Luminant Energy Company LLC would pay $1.1 million under a settlement with Staff of the Public Utility Commission of Texas to resolve alleged violations of Electric Reliability Council of Texas (ERCOT) Protocols §§ 6.4.6(1) and 8.1.1.2.1.3(4).

The settlement states that, on July 30, August 5, August 11, and August 12, 2015, fifteen Luminant quick start units at the Permian Basin, Morgan Creek, and DeCordova generation sites simultaneously telemetered a down ramp rate of zero when operating near maximum capacity.

The settlement states that because of the zero down ramp rate, during this time, ERCOT's Security-Constrained Economic Dispatch (SCED) was prevented from dispatching the units down.

The settlement states that these instances were the only time in 2015 where Luminant telemetered a zero down ramp rate for a quick start unit. Since August 12, 2015, Luminant has not telemetered a zero down ramp rate for any quick start unit while operating in peak fire mode.

The settlement states that the zero down ramp rate was generally held for two hours, with actual times varying between 30 minutes and two hours and 39 minutes. The settlement states that the zero down ramp rate was held for an aggregated 119 operating hours between all units.

The settlement states that most of these quick start units were obligated to provide non-spin reserve service (NSRS).

The settlement states that, of the aggregated 119 operating hours where Luminant telemetered a zero down ramp rate, it carried non-spin obligations in 109 operating hours.

Under ERCOT Protocols § 6.4.4.2(a), units providing NSRS may participate in the real-time energy market and still meet the NSRS obligation by offering energy from NSRS-obligated capacity at prices of $75/MWh or higher.

The settlement states that, on the days at issue, all of the units were offering energy at less than $76/MWh and were dispatched by SCED because locational marginal prices (LMPs) had risen above $75/MWh.

The settlement states that, because SCED was unable to adjust these units down, the units continued to generate near peak output, effectively overriding SCED to permit the units to operate at the output level determined by Luminant rather than the output level that would have been determined by SCED.

Under ERCOT Protocols § 6.4.6(1), QSEs shall provide ERCOT with accurate telemetry of the current capability of each Resource including the Resource Status, Ramp Rates, HSL, and LSL.

Under ERCOT Protocols § 8.1.1.2.1.3(4), QSEs providing Non-Spin must be capable of responding to ERCOT Dispatch Instructions.

Luminant asserts the following:

a. The combustion turbines at DeCordova, Morgan Creek, and Permian Basin were operating in peak fire mode on July 30, August 5, August 11, and August 12, 2015 -- a method of operation that maximizes the unit's production of energy available to the ERCOT grid -- at the times that Luminant telemetered a zero down ramp rate to ERCOT for these units.

b. These combustion turbine units are mechanically incapable of automatically following down dispatch instructions while operating in peak fire mode.

c. Consequently, the zero down ramp rate reflected Luminant's belief of the units' capabilities at that time with respect to ramping down.

Commission Staff asserts the following:

a. While peak fire mode prevents the turbines from following SCED instructions, nothing about the mode prevents the units from manually ramping downward. Further, the plant operator is always capable of taking the unit out of peak fire mode in order to follow dispatch instructions.

b. When the LMPs at each location dropped below $75/MWh during the days at issue, the units continued to generate near peak output because SCED was unable to adjust these units down due to the zero down ramp rate.

c. Commission Staff is unaware of any occasion other than those on July 30, August 5, August 11, and August 12, 2015 where Luminant telemetered a zero down ramp rate while operating in peak fire mode. After investigation, Commission Staff believes it has found more than 250 instances of Luminant telemetering a down ramp rate greater than zero while operating in peak fire mode.

d. From July 30 to August 15, 2015, Luminant regularly offered these units above $1000/MWh, at times increasing above $2500/MWh.

Docket 48607

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