Roughly a year ago, Spain and Portugal went dark when the electrical grid of the entire Iberian Peninsula failed. While the grid operators did a heroic job of restarting the grid quickly, there were obvious questions about what had led to the blackout in the first place. A preliminary report suggested that a combination of grid-level voltage oscillations and early disconnections was the main factor. Over the weekend, the European grid coordinator, ENTSO-e, released its final, detailed report on the event. While it's largely consistent with the preliminary conclusions, the report provides much more detail about what went wrong and, more significantly, offers a clear picture of how the Iberian grid operators could make changes to prevent a similar event in the future. ## Oscillations The expert committee that prepared the report had access to a wealth of data, including status logs from most of the major hardware on the Spanish and Portuguese grid, often recorded with sub-second precision.…