Synchronization of electrical power grids

Electrically connecting a first node of a first power grid to a second node of a second power grid includes: determining a phase angle of at least one phase of an AC voltage at the first node in the first power grid; determining a phase angle of at least one phase of an AC voltage at the second node in the second power grid; determining a phase angle metric based on comparing the phase angle of the AC voltage in the first power grid to the phase angle of the AC voltage in the second power grid; comparing the phase angle metric to a phase angle threshold; and if the phase angle metric is equal to or exceeds the phase angle threshold, controlling a dispatchable energy source in the first power grid in a P-Q control mode to adjust the phase angle of at least one phase of the AC voltage at the first node.