Two workers were injured in the attack, according to DTEK, Ukraine's biggest electricity operator.
It provided no further information, including the plant's location.
Ukrainian authorities release few details about the routine Russian attacks on its power grid so as not to give away intelligence to the enemy.
Repair crews, meanwhile, work around the clock to undo the damage.
The energy sector has been a key battleground since Russia launched its all-out invasion of its neighbour more than three years ago.
Each year, Russia has tried to cripple the Ukrainian power grid ahead of the bitter winter, hoping to erode public morale and disrupt military manufacturing.
Ukraine has accused Moscow of weaponising winter.
Ukraine's winter runs from late October through to March, with January and February the coldest months.
Ukraine, meanwhile, has been hitting back with long-range strikes on the Russian energy supply, recently causing outages in some Russian regions along the border.
The Russian Defence Ministry said on Wednesday that its air defences overnight intercepted 53 Ukrainian drones over nine Russian regions.
The Ukrainian town of Shostka, in the northeastern Sumy region, has been hard hit by the Russian onslaught against the power supply, officials say.
Authorities there have put up tents where locals can warm up, drink hot tea, charge their phones and receive psychological support, according to regional head Oleh Hryhorov.
He posted photos on Telegram of people cooking in outdoor kitchens in the street over open fires on Tuesday.
Shostka Mayor Mykola Noha posted the locations of 11 places in the town where locals can get food and tea.
"Please bring your own dishes," he wrote on Facebook Wednesday morning.
Russia also struck energy infrastructure in Ukraine's northern Chernihiv, southern Kherson and southeastern Dnipropetrovsk regions, authorities said.
Ukraine's air force said it intercepted or jammed 154 out of 183 Russian strike and decoy drones fired at the country overnight.
Meanwhile, Ukrainian rockets killed three people and wounded one more in Russia's Belgorod border region, where previous attacks have brought power outages, Governor Vyacheslav Gladkov said on Wednesday.
