By Tom Kleckner
LITTLE ROCK, Ark. — SPP conducted its second wind summit in as many years last week, delving into the technical details of a recent study that indicated the RTO could handle wind penetration levels of up to 60% with additional transmission and monitoring tools.
As if to underscore the point, SPP’s balancing authority recorded new records for wind peaks and penetration levels during both nights of the summit.
“I find it ironic that during this summit, we’re predicting 43% wind penetration levels tonight and 48% tomorrow night,” said Casey Cathey, SPP’s manager of operations engineering analysis and support, as he kicked off the presentations and discussion.
SPP set new wind penetration levels of 43.3% Feb. 17 and then 43.9% after midnight on the early morning of the 19th. The penetration levels shattered the previous record of 39.1%, which lasted all of 18 days.
SPP also topped 10,000 MW of wind energy for the first time Feb. 17, recording a new wind peak of 10,439 MW. That eclipsed the old mark of 9,948 MW set in December. The Feb. 19 wind peak was 9,804.5 MW, when load was 22,332 MW.
The RTO began the year with 156 wind resources totaling 12,400 MW of installed capacity, accounting for almost 14% of its fuel mix. It expects to finish 2016 with 16,960 MW of wind generation and to add at least 2,035 MW more in 2017.
Because of the amount of wind generation being brought online in its 14-state footprint, SPP last year commissioned its first wind integration study since 2009. The analysis was presented to the Markets and Operations Policy Committee last month. (See Study: 60% Wind Penetration Possible in SPP.)
“We’re looking at [potentially] 12 [GW] of wind today,” Cathey said. “We want to ensure we continue to operate reliably and economically with this wind.”
The reliability-based study analyzed wind penetration at 30%, 45% and 60% of load during spring and fall seasons and compared them to current system conditions. SPP staff, with an assist from the Electric Power Research Institute, also performed steady-state thermal and voltage analyses, and voltage-stability, re-dispatch and ramping analyses.
Not surprisingly, staff said as wind penetrations increased, they saw “significant” transmission constraints, along with system overloads and wind farm curtailments. Cathey said SPP has sufficient ramping capabilities for today’s wind penetration levels, but vast swings in wind’s intermittency can cause problems.
“We can go from 1,000 MW to 9,000 MW and 9,000 MW to 50 MW over the course of hours,” he said. “We’re preparing for that and ensuring we’re not too fat or too lean.”
Cathey said the study showed the need for additional transmission beyond those projects identified by SPP’s current planning process. The study also calls for expediting approved projects, monitoring ramping issues with real-time operations tools and providing additional flexibility for non-dispatchable variable energy resources.
Cathey said staff will next develop a cost-benefit analysis comparing the cost of accelerating projects with the benefits of additional wind penetration. The analysis will be vetted by stakeholders, being first shared with SPP’s Transmission Working Group during the next two months.
The cost-benefit analysis and a transient stability analysis are both likely to be part of the wind integration study’s second phase. The scope has yet to be determined, with staff asking for stakeholder feedback.
“We’re definitely looking into what else do we not know,” Cathey said.
“This gives us a baseline to get the discussion off the ground,” said SPP senior engineer Jason Tanner. “With this study, we can look farther into the future.”
SPP wasn’t the only RTO that set records for wind the night of Feb. 18-19. MISO hit a peak of 13,084 MW, surpassing the previous 12,720-MW record. Meanwhile, ERCOT topped out at 14,023 MW with a penetration level of 45%.
