Anna Blaustein in Scientific American:
On February 24 Ukraine’s electric grid operator disconnected the country’s power system from the larger Russian-operated network to which it had always been linked. The long-planned disconnection was meant to be a 72-hour trial proving that Ukraine could operate on its own. The test was a requirement for eventually linking with the European grid, which Ukraine had been working toward since 2017. But four hours after the exercise started, Russia invaded.
Ukraine’s connection to Europe—which was not supposed to occur until 2023—became urgent, and engineers aimed to safely achieve it in just a matter of weeks. On March 16 they reached the key milestone of synchronizing the two systems. It was “a year’s work in two weeks,” according to a statement by Kadri Simson, the European Union commissioner for energy.