German power producer RWE is working to reconnect five units of its Rhenish lignite power plant in the east to the grid after an incident on Tuesday evening that forced it to take 4.2 gigawatts of capacity offline, it said in a press statement on Wednesday.
Media reports say that German police are investigating acts of sabotage targeting the grid.
Reuters reported that devices with conductive material caused damage to power lines in the state of Brandenburg in the east, prompting RWE to take capacity offline without affecting power supplies.
Another attack took place in the west of the country near Bergheim, where explosive devices damaged power lines.
The Reuters article said that the grid operator, Amprion, said that external interference was likely.
While it did not mention suspects, Germany on Tuesday said it had found proof that Russia was behind the flying of a drone at Leipzig airport in August that was carrying explosives but failed to detonate, an act characteristic of Russia's so-called hybrid warfare.
Bloomberg reported that the earlier attack on transmission lines in eastern Germany used homemade projectiles and caused a supply outage at the LEAG Janschwalde coal plant.