Pro-Ukraine hacker group OneFist claims hacked SCADA system for Rosseti Lenenergo's 110 kV substation PS-249 "Dymi" as part of their special cyberwarfare operation, Operation "Smoked".
Using a vulnerability in it's uninterruptible power supply (UPS), which gave them total access to the batteries, they successfully demolished the system, forcing the batteries into overheating and torching the system's sensors.
According to energybase[.]ru, this system cost $1.3 million, or 84.8 million rubles. Based on OneFist's calculations, it controlled an estimated 2,000 separate sensors which regulated the substation and monitored it's health. They believe that the destruction of all these sensors will disrupt power supply in the Leningrad region/SPB.
Sources: OneFist's Telegram and Twitter channel