National Electricity System and Sunday’s Power Failure.
Written by José Luis Apodaca
Everything seems to indicate that a failure at the San Jerónimo substation caused the outage of the North Eastern and Northern systems (a 7,500 MW load on Sunday with ambient temperatures below 30C; on Monday it most probably increased to 10,000 MW).
I still think that the basic selective protection principle should have been followed: if the failure is at one substation they must open the switches closest to the failure (all those in S.E. San Jerónimo); or failing that, the backups in the neighboring substations: Plaza and Villa de García)
It is very likely that the failure to coordinate multiple protection devices caused loss of stability, and with it the output of 400 KV lines along with very important generation inputs (Río Escondido and Carbón II, in addition to CC of Rio Bravo, with a total of 3,500 MW). The delay in the operation of low frequency relays caused a loss of the power generation that had been in operation.
I think this argument is more convincing than the official one about electric arcs leading to overvoltage in suboptimal conditions....