Basically, there are people using power on the grid without paying anyone to generate a corresponding quantity. This means that less power is going into the gr

Basically, there are people using power on the grid without paying anyone to generate a corresponding quantity. This means that less power is going into the grid than is being taken out of it, an amount that has accumulated since January to a bit over 100GWh. This missing 100GWh of energy has been collectively sapped from the inertia of the all spinning synchronous machines connected to the grid - mostly generators, but also motors - as a result of which they are spinning slower than they should be. Slowing spinning synchronous generators means a lower grid frequency.