Enron started it but the other power companies have all picked up the practice of playing the spot market for energy production and consumption. This works a lot like the Wall Street Futures Market where there is certain amount of financial speculation that goes on around both the supply and demand.
If demand is high, providers will buy extra power to cover the extra demand. If demand is low, producers sell it cheaply. If you can buy it cheaply and then cause a sudden surge in demand, you can now sell it at a profit. You can also do the inverse and cause a lot of economic losses by creating a fake surge in demand, causing providers to buy a lot of power at a high price, then selling high, and shutting down leaving the providers holding the proverbial bag.
Given that we know about Fancy Bear hacking energy companies and the US Department of Energy, you can guess who I think is behind it. I think Russia found a way to drive the world oil market back up. Increase demand….