Engineering360: "Primary causes of power outages"

DC is undervalued for another reason. Making intra-grid connections via a DC link allows each grid to be frequency independent. Thus high loads can result in a voltage decrease--akin to a brownout.

The Pacific Coast Intertie is an example of such a UHV DC link, spanning over 1000 miles.

DC has two other advantages over AC. The AC lines act like capacitors, with current flow but not power delivery due to their charging and discharging. DC gets charged once. AC also can act like an RF transmitter at 60 Hz, so as line lengths get up closer half the wavelength the lines lose power into RF radiation. Again, a DC link eliminates this problem.

I thought the NorthEast blackout began at one plant near the edge of the grid. When it went off line the next plant was hit with the load the first one had shed, causing it to lose synchronization, so it also went off line. This continued across the area. Yes, the settings of the protective relays can be called a "bug" but there was much more to it. A large number of plants have trouble doing a "black start".

I would have appreciated more in the way of statistics--size of outage and duration, for example. Cause in numbers not generalized words.

--JMM