CAISO Agrees to Pay Penalties for Brief San Diego Blackout

The California Independent System Operator (CAISO) admitted to reliability standards violations connected with a 43-minute San Diego blackout on March 31, 2010, and agreed to pay a civil penalty of $200,000, says an order issued by the Federal Energy Regulatory Commission (FERC) on Friday.

The order resolves an investigation by the federal regulator’s enforcement arm regarding the California grid operator’s compliance with reliability standards, FERC said. CAISO has voluntarily undertaken "substantial efforts" to address concerns identified during its own internal review following the disturbance, and it is expected to make semi-annual compliance monitoring reports to FERC staff for up to two years, the agreement says.

The disturbance occurred on March 31–April 1, 2010, in the San Diego region of CAISO’s area when a shift supervisor working in CAISO’s Folsom control room reportedly issued two erroneous directives to San Diego Gas and Electric Co. (SDG&E) to shed 290 MW of load. Acting on those directives, SDG&E shed 332 MW of firm load, depriving about 250,000 SDG&E customers of electricity for up to 43 minutes. CAISO later issued a press release acknowledging that it “made mistakes, first allowing this situation to occur by not maintaining adequate local generation in San Diego, and then applying operating requirements incorrectly.”

According to FERC, CAISO is responsible for operational control of the CAISO-controlled grid consisting of transmission lines and associated facilities for the participating transmission owners (including SDG&E). Those responsibilities include enforcement of the 25% internal generation requirement for the SDG&E area, which requires that internal generation be maintained at 25% of the native load at all times.

"Although CAISO knew that [InterGen’s 322 MW La Rosita II unit in Mexico] would not provide Internal Generation needed to maintain the 25 percent Requirement on April 1, CAISO failed to plan for replacing that Internal Generation," the order says.

Sources: POWERnews, FERC