Two years ago Dominion Virginia Power warned of dire consequences to the Virginia Peninsula if the company could not build a 500 kV transmission line across the James River. An analysis prepared by engineering consulting firm Stantec and submitted to the U.S. Corps of Engineers left little to the imagination:
Dominion will be required to implement pre-contingency load shedding (i.e. rolling blackouts) in the [North Hampton Roads Load Area] to prevent the possibility of cascading outages impacting the reliability of the interconnected transmission system. … It is estimated that rolling blackouts would initially occur 80 days a year and would continue to increase in number as load continues to grow in the area. …
The potential exists that up to 50% of the customers in this load area could be without electricity for days or even weeks until the event which caused the failure could be fixed.
Yesterday I posted an article based on an interview with Steve Chafin, Dominion director of transmission planning and strategic initiatives, that seemed to tell a different story. While the utility still said the Peninsula will be at risk for 50 to 80 days a year after shutting down the Yorktown Power Station’s No. 1 and No. 2 generators April 15, the ability to continue running the No. 3 generator up to 29 days a year will reduce that threat to about 50 days. Only if an unplanned event knocked out a transmission line — something that has happened only six times the past ten years — on one of those days would Dominion have to shed load. While there are no guarantees, Chafin told me, “We think we can get through the summer without any rotating blackouts.”
After publishing the article, I got to thinking about the marked difference in tone. Two years ago, when Dominion was trying to push the Surry-Skiffes project through regulatory approval in the face of intense opposition by preservationists, the company was stressing how disastrous things would be if the project wasn’t built. Now that the permit review by the Army Corps of Engineers is reaching its final stages and a mitigation settlement seems imminent, Dominion is downplaying the risk.
Yesterday I asked Chafin and Le-Ha Anderson, a Dominion spokesperson, to explain the change in rhetoric. They stand by what Dominion said then, and they stand by what Dominion says now, and they say there’s a legitimate explanation.
The difference between then and now is that Dominion has set up a Remedial Action Scheme (RAS).
Dominion worries about an uncontrolled, cascading blackout emanating from the Peninsula, the most vulnerable zone in the Dominion electric system and one of the most fragile in the 13-state PJM Interconnection territory. If blackouts erupted there, Dominion’s grid models can’t predict where they would stop. The United States conceivably could experience an outage as widespread as the infamous 2003 Northeastern blackout that knocked out power to millions.
With approval from the Southeastern Electric Reliability Council and PJM Interconnection, Dominion has set up an RAS to isolate the Peninsula if an unplanned outage occurs. “We put in an automatic, specialized relay scheme,” says Chafin. “If it senses certain conditions, it will immediately drop load to 150,000 customers.” The draconian action will prevent a cascading shut-down of transmission lines emanating from the Peninsula to points beyond.
Before the Remedial Action Scheme, Dominion would have had to implement rotating blackouts on high-load days before a component failure or other disruption occurred. Because the RAS responds immediately when needed, it allows Dominion to implement blackouts after the disruption.
While implementation of the RAS under a worst-case scenario would cause a massive outage on the Peninsula, it would nip in the bud an uncontrolled blackout that could rip through the nation’s electric grid. The chances of it occurring are remote, however, and it reduces the necessity of initiating precautionary, controlled blackouts when the Peninsula region reaches peak electric load some 50 or so times a year.
“We have a responsibility to provide reliability to our customers. We have an equally important responsibility to protect the safety and integrity of the grid,” Chafin says. “The automation will help to reduce the risk on a short-term and temporary basis.”
The Remedial Action Scheme will be available until the Surry-Skiffes transmission line receives regulatory approval and construction is complete, a process that will take at least another 18 months.
“We’ve been working on a Peninsula solution for a long time,” says Anderson. “We filed in 2013, and have worked with the Corps for almost four years. This is a serious situation. … We’ve had to look at what other things we can do in the meantime. This is a temporary, short-term tool that will help get us through the most critical period.”
Leave a Reply
You must be logged in to post a comment.