Houston — Real-time prices in the Electric Reliability Council of Texas spiked to $5,800/MWh for 15 minutes Tuesday morning, while the grid operator deployed non-spin reserves around the same time.
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Furthermore, real-time prices crossed the current energy offer cap of$9,000/MWh during two 5-minute intervals.
"For the first time in ERCOT's history, market prices reached the $9,000price cap during two [Security Constrained Economic Dispatch] intervals ...for a total of about 10 minutes," ERCOT spokeswoman Leslie Sopko said Tuesdayin an email.
Sopko added that ERCOT had no resource adequacy issues Tuesday morning,but did have a few minutes of ramping issues because of colder weather and higher-than-expected load, causing a brief spike around 7 am CST.
The 15-minute interval real-time prices started to climb at 5:30 am CST,topping $250/MWh before rising to $500/MWh 15 minutes later, before eventuallylanding at nearly $5,800/MWh at 7 am. It retraced back to normal since,averaging in the high $30s/MWh as of 10:15 am CST.
Systemwide demand rose from 41.3 GW at 6 am to 46.2 GW at 7 am and toppedout at 48.3 GW at 8 am, where ERCOT forecast to be the peak level for the day.
After that, load started to fall through the rest of the day, reaching46.8 GW at 9 am and forecast to bottom out at 34.3 GW at 4 pm. But peakload of48.3 GW came in above the day-ahead forecast of around 47 GW.
On the other hand, ERCOT wind output only reached 3.3 GW at 6 am, around15% lower than the day-ahead forecast for the hour, and fell to 2.8 GW at 7am, about 12% lower than projected.
Around 6:45 am, ERCOT said about 1 GW of non-spin reserve was deployed,and about 60% of that was recalled about half an hour later before all of themwere recalled around 7:30 am.
According to ERCOT, non-spin reserve refers to the offline generationresources that can be synchronized and ramped to a specified output levelwithin 30 minutes or load resources that can be interrupted within 30 minutes,both of which can operate or be interrupted at a specified output level for atleast one hour.
ERCOT also said the following four scenarios would cause non-spin reserveto be deployed:
* Detection of insufficient capacity for energy dispatch during periodicchecking of available capacity.
* Disturbance conditions such as a unit trip, sustained frequency decayor sustained low frequency operations.
* SCED not having enough energy available to execute successfully.
* When offline generation resources providing non-spin are the onlyreasonable option available to the operator for resolving local issues.