The Imperial Irrigation District energy system was running pretty well during the day Sept. 5.
Operators were looking ahead at the load forecasts and bringing in power as usual.
Then a call came in. The California Independent System Operator and California Office of Emergency Services was on the line around 2 p.m. saying there may be more power shortages in the state than anticipated.
Imperial Irrigation District was planning on getting 300 megawatts of power from the state’s power grid operator, CAISO, enough energy to power about 250,000 households.
But around 4:30 p.m., IID was informed that power order would be cut, district General Manager Henry Martinez said at the Sept. 8 IID Board of Directors meeting. This last-minute notice put a wrench in the works of the district’s plans on how it would be getting a large chunk of energy for the evening of Sept. 5.
The loss of that contract started a string of events, including starting up units that were on standby, utilizing the district’s battery and looking for additional energy. It also triggered “load shedding” for IID customers.
The way load shedding is programmed to work is some customers are without power for 15 minutes at a time, and then it rotates to different locations the district’s service area at random.
And it worked that way in some situations. However, in other cases it lasted more like an hour to an hour and a half, Martinez said. That was due to a problem with a switch of the circuit breaker at a substation.
The load shedding lasted about two hours before the district’s power system was stabilized and officials were able to close the circuit breakers.
It’s estimated around 22,000 customers were without power at some point, most of those customers affected by the rotating outages were impacted for 15 minutes, IID spokesman Robert Schettler said.
The district is looking into the mechanical issues that caused the extended outages in certain areas.
But what about the power that was supposed to be there?
The district plans to send a letter to CAISO asking why the district was not notified with plenty of time to prepare, and why the district had to make emergency energy purchases.
“We’re going to follow up with Cal ISO about what failed in the notification process, because that 300 megawatts, if we’re going to be curtailed of energy, we should have been given plenty of warning that this was going to happen so that we could respond in more of a timely manner,” Martinez said.