By Tom Kleckner
OKLAHOMA CITY — SPP could handle wind-penetration levels of up to 60% with additional transmission and monitoring tools, officials told the Markets and Operations Policy Committee last week.
The RTO’s first wind integration study since 2009 found that wind energy, which represented about 14% of system capacity at the end of 2015, will expand significantly based on requests in the interconnection queue. The study analyzed SPP’s transmission area for system reliability breakpoints due to increased wind generation and said additional operational procedures should be considered “to reliably operate above the currently installed maximum wind capability.”
If its recommendations are implemented, the report said, SPP’s transmission system could “reliably handle” wind representing up to 60% of internal SPP load. The RTO saw record wind-penetration levels last year approaching 39% and a record wind peak of 9,948 MW. (See SPP, ERCOT Set New Wind Peaks.)
SPP studied wind-penetration levels of 30%, 45% and 60%. A voltage-stability analysis indicated renewable penetration levels are approaching current limits. SPP also analyzed wind energy ramping, re-dispatch and outages and steady-state thermal and voltage.
“We’re at those levels where [previous] studies said we would start having issues,” said Casey Cathey, SPP’s manager of operations engineering analysis and support. “We could have situations where we hit 45% without reliability concerns, but is that for an hour or sustained?”
Cathey said SPP has 156 wind farms totaling 12,380 MW of installed capacity and will reach 16,960 MW of installed wind at the end of 2016. SPP projects at least 2,035 MW will be added in 2017.
The report calls for expediting transmission projects, noting that about half of the 4,580 MW of wind expected to be added this year will require new lines. It also shows the need for “some limitation before we can build out the system further,” Cathey said.
It also recommended installing voltage reactive support capabilities for existing wind farms; enhanced operations tools, to monitor real-time voltage stability limits; allowing the reliability coordinator additional flexibility in re-dispatching; new planning criteria for and evaluation of phasor measurement units to provide real-time situational awareness.
“It’s worthy to note SPP put a significant amount of wind growth in the system,” The Wind Coalition’s Steve Gaw said. “It’s working … we have high penetration with low loads, and we’ve been able to do that reliably.”
Cathey said SPP is “good at forecasting wind,” but that ramping issues take place in two- to three-hour timeframes, not five-minute intervals.
“We know it’s going to ramp,” he said, “but we don’t know when. We know it will happen in the morning, but we don’t know if it’s 6:30 or 7:30.”
Cathey said SPP is continuing to improve its weather forecasting, which is supplied by energy & meteo systems. MISO also uses energy & meteo.
SPP has scheduled a wind-integration summit Feb. 17-18 at its headquarters in Little Rock, Ark. Cathey said the summit will provide stakeholders an open forum to ask questions, provide feedback and critique the study’s results.
