The Russians need to slow down the massive deployment of Ukraine’s reserves from Kharkiv to Ugledar in the South.
Russia is also redeploying its reserves, but they have far further to travel to get their reserves to Ugledar (Zaporizhzhie), and it’s taking longer. The shipment of reserves by Ukraine is being done by rail. Taking out the electric also stops the railways.
Ukraine is moving hundreds of armoured vehicles to the South. They lost 20,000 soldiers in their Kherson offensive and they urgently need to reinforce. The Ukrainians also wish to launch a further land offensive in the Zapoizhzhie area – around Ugledar. The Ukrainians have been attacking the power plant at Energodar for weeks and it’s been closed down by the Russians. This is not simply a revenge strike by Russia but a strategic move to block the movement of tanks and armoured vehicles to the next offensive.