On a bright winter day, workers at a Ukrainian thermal power plant repair its heavily damaged equipment as drops of water from melted snow leak through gaping holes in its battered roof.

Several weeks earlier, the facility was targeted by a Russian air attack that left scorch marks, shrapnel scars on the walls, and missile fragments scattered across the production floor.

"This is our life now. Workers at a thermal power plant that's supposed to produce electricity are walking on frozen floors and using firewood to keep warm," Oleksandr, 52, head of the Production Management Department, told The Associated Press.

He spoke on condition that only his first name be used citing security concerns.

Repeated Russian strikes on infrastructure have seriously impacted Ukraine's energy sector often resulting in rolling blackouts across the country.

On Thursday, Moscow launched another large-scale air attack. Ukrainian authorities said nearly 200 drones and missiles targeted infrastructure, d isrupting power supply to more than a million people.

The scale of the ongoing work to fix the sector is huge. Since the start of Russia's full-scale invasion in 2022, the G7 and other allied countries have allocated more than $4 billion in energy assistance to Ukraine, U.S. Secretary of State Antony Blinken said in September.

Oleksandr, who works at the power plant operated by Ukraine's largest private energy company, DTEK, says since the station was first attacked in November 2022, it has been unable to return to full capacity due to continuous strikes that have left critical equipment in ruins.

The exact location of the plant visited by the AP, details on the damage and even workers' last names cannot be disclosed for fear this information could help Russia coordinate future attacks.

DTEK operated around 20% of Ukraine's electricity production before the full-scale invasion, but this figure dropped to 12% since the war broke out.

The company says its facilities have been attacked by Russia almost 200 times since 2022. They also say nearly 90% of the company's infrastructure was destroyed or suffered damage and that was before Russia launched its large-scale attack on Nov 17.

Oleksandr says he expects repairs at the station to continue through the winter into next year, and potentially far beyond.

Repair efforts at the plant are further complicated by the fact that some critical equipment was manufactured in the Soviet Union and finding parts is now difficult.

To mitigate this, some former Soviet countries who are now Ukraine's allies have helped supply equipment. "Potentially, Western countries could also help us with equipment, but their power grids have different characteristics," Oleksandr said.

Only half of DTEK's generating capacities have been restored since the first attacks on its plants in November 2022 until the latest large-scale strike. Earlier this week, the European Commission and the U.S. government a nnounced a donation of $112 million in equipment and construction materials to help DTEK prepare for the winter.

With the war in its third year, staff at DTEK's plant have adapted to the grim reality of their day-to-day existence. They know the protocols by heart.

Not everyone can take shelter during an air alert. A minimal crew must remain in the control room to oversee operations, putting themselves at risk of a direct strike.

"You have to sit and wait while monitoring the trajectories of whatever was fired, but the power units keep working so we cannot just leave, we stay in the control room," said Dmytro, 41, a power unit operator at the plant.

Despite the challenges, Dmytro and his colleagues press on, driven by a mission to keep the lights on in their town and region over the winter months.