Behind SDG&E’s 9-20 System Collapse

SDGE1September 20th was an unusually hot day, even for San Diego.  But San Diegans got even hotter under the collar when SDG&E slammed the region with rolling blackouts without any notification.  It was the worst possible timing for any blackouts as high temperature records fell all over San Diego County.   Temperatures were reported to be 16 degrees above normal…….yet at the time, the state claimed it had plenty of power.    SDG&E was tight-lipped, claiming only that the California Independent System Operator (CAISO) ordered it to shed 150 megawatts. Meanwhile, representatives of the CAISO were even tighter-lipped, claiming that they were “assessing the situation“.    The CAISO website was silent — it did not even mention any event in San Diego.  The CAISO reportedly told the City News Service that it was not clear on what was happening.  The San Diego news media was baffled, reporting only that 115,000 customers had power cut when an unidentified generator failed.   So what the hell happened?

The major failure was that the elaborate outage system put in place by SDG&E (and paid for by the area’s power customers) didn’t work.   Here’s specifically what went wrong:

  • SDG&E’s website failed as the outages hit, making it difficult for residents to get information about the power loss.   Customers who went to SDG&E’s outage map saw only that there were scattered outages and that the utility was “assessing the outage to determine the cause” the causes.  The company tweeted at 1:54pm that it was “working hard to fix an outage in the Clairmont (sic) area” seemingly oblivious that the outage was caused by the company’s own load-shedding strategy.   Ironically, one of the areas that SDG&E blacked out was the Kearny Mesa area that was suffering from a record high 96 degrees  (the previous record had been 87 degrees).
  • When it did work, the outage map wasn’t accurate.   While it showed scattered outages in Clairemont and Linda Vista,  sections of busy Mission Valley were blacked out.
  • SDG&E’s “rotating outage” notification system also was inoperable;  customers were supposed to have been able to view rotating outages, but no such information was displayed.  According to KNSD, no customers were notified in advance of the outages.
  • Because power was interrupted, SDG&E customers’ wifi systems were inoperable.   So customers had to use their mobile phones connected to cellular networks to view the outage map……yet the SDG&E outage webpage wasn’t configured to be read on all mobile phones, rendering the page unfathomable to some customers.
  • SDG&E conceded that its contact center and website were having “technical issues” in the midst of the rolling blackouts.
  • SDG&E’s media center was unresponsive.  News outlets reported that its call center was getting large numbers of calls, yet SDG&E’s phones were unanswered at the SDGE media office, and other than one Tweet attributed to an Cathleen Romero at SDG&E there was no official reports of unusual problems.   The following day, SDG&E posted a terse announcement blaming the CAISO for the blackouts.
  • The CAISO event notification system didn’t work.   News media outlets were supposed to receive notice from the CAISO in the event of any interruption in service.  Yet, throughout the day and even into the next day, CAISO issued no such notice and remained silent on the outage attributed to it.

As of next day, September 21st, some additional information trickled out.   Most notably,  a local generation plant  (probably Otay Mesa, but the UTSanDiego declined to identify it) dropped off line at 11:50am.  At about 1:15pm, the CAISO ordered SDG&E to shed load.    During that 85 minute period, SDG&E inexplicably failed to send emails to its customers or notify the media warning of possible rolling blackouts in the coming hours.   In fact, the media wasn’t notified until almost an hour after the blackouts began.  The blackouts rolled through San Diego and South Orange counties for about four hours.

Grid ops insiders initially were under the belief that the rolling blackouts were only supposed to last 20 minutes and effect a few thousand customers.   However, the rolling blackouts were extended and ended up impacting over 115,000 — most of whom were served by newer circuits that had SCADA (interactive communication links) installed.   So the most updated….and arguable efficient customers on the distribution grid bore the brunt of the outages.  Apparently, SDG&E has no circuit priority list other than the newer circuits with this SCADA functionality.

The larger questions regarding this blackout remain unanswered:

  1.  Why did the Otay Mesa Generating Station go offline?
  2.  Given the record temperature forecasts, why did SDG&E not have sufficient power in reserve?
  3. Why was there not sufficient power on SDG&E’s two major transmission lines  (Sunrise and Southwest Powerlink) to compensate for the load imbalance caused by the loss of a  local power plant.
  4. Why did SDG&E’s Grid Ops director not initiate the emergency operations center protocols that would have sent out emails about the event to SDG&E employees and the public?
  5.  Why were neither SDG&E customers or the local media given warning of blackouts during the 85 minute period between when the plant went off line and the CAISO issued its orders  (SDG&E controllers are in constant contact with the CAISO during such events, so the need for load shedding had to have been discussed)
  6. What happened to SDG&E’s rotating outage notification system?
  7. What were the “technical issues” that caused SDG&E’s website and its outage map to malfunction?
  8. Why did the CAISO not acknowledge its role in the load shedding decision until the following day?    Moreover, why has it continued to remain silent on the events surrounding the blackouts.

SDG&E insiders say that the utility has begun an “internal investigation” and has demanded that employees not talk to one another about the events that occurred on that day.   There’s no word about who is conducting this investigation.  Until these questions are answered, San Diego cannot be sure that the expensive electric transmission and distribution system paid by SDG&E ratepayers will work to keep power on when a local power plant malfunctions.


2 replies
  1. William Blake
    William Blake says:

    I work for a municipal utility here in California, we also are under CALISO balancing authority. When ever they call we must obey all orders (start more generators, or even shed firm customer load, etc), and must have a valid reason for not obeying them else the company will occur a very stiff penalty. This is usually due to a generator being out of service or fails to start. Can’t think of a valid reason not to shed customer load when ordered…. SDGE like many larger utilities have load shed programs that must be started and completed within mins of the shed order.

    • admin
      admin says:

      Thanks for your comment, but you may have missed the point. Utilities are legally obligated to follow CAISO rules. But SDG&E failed to notify its customers of the shed order and its customer interactive resources pretty much failed across the board. Moreover, SDG&E’s Mission ops center even failed to notify other SDG&E departments of the impending load shedding order, so other company departments were not able to respond appropriately. But there’s little dispute over the fact that if and when the CAISO orders load shedding, a utility has to comply.


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