Electrical generation and distribution is a tough business. Places where you have generation capacity aren't necessarily accessible via the transmission network. So if NYC isn't using power, you can't just send it to Cleveland. Sometimes, you have a certain amount of "fixed" generation capacity that you must use, or must commit to taking offline for days before restarting. 80% of your power may come from a few big, centralized, cheap power plants (nukes, big hydro, coal) and a bunch of geographically dispersed, small, more expensive plants that you spin up to meet peak demands. (natural gas, small hydro)
Utilities sign contracts with big industrial users who have steady-state energy demands to ensure that they have a place to send lots of power to. They also have contracts that when peak demand is reached, the industrial customers shut down lines in exchange for discounts. (I worked at a place that financed a DR datacenter largely by committing to failing over 50% of our energy workload to another region during a peak demand emergency.)
I'm not doing the topic justice, but there's alot of behind the scenes stuff there -- I'm sure it wasn't just a contract dispute.
From the article it doesn't sound like there was any sort of dispute...my guess would be that the contract formalized payment as a function of capacity and demand, in such a way that payment could be negative. This might not even be a mistake or from a need to distribute the power, it could just be a low-cost (due to rarity) sweetener.
Utilities sign contracts with big industrial users who have steady-state energy demands to ensure that they have a place to send lots of power to. They also have contracts that when peak demand is reached, the industrial customers shut down lines in exchange for discounts. (I worked at a place that financed a DR datacenter largely by committing to failing over 50% of our energy workload to another region during a peak demand emergency.)
I'm not doing the topic justice, but there's alot of behind the scenes stuff there -- I'm sure it wasn't just a contract dispute.