How the grid works, why a distributed grid won’t work
Preface. This book is a good primer on how the grid works, worth the price to me just to understand Volt-Ampere Reactives (VARs). Renewables don’t provide them, but they’re essential for keeping the grid stable and not coming down. Angwin describes VARs as a bit like “riding a bicycle. The energy you put into the pedals will move the bike forward, but you also have to put some energy into maintaining your balance, or you’ll fall over and won’t be able to move forward at all. If you are a good bicyclist on a smooth road, the “maintaining your balance energy” will be small. If you are a poor bicyclist who swerves around a lot, or if you’re on a bad road, the “maintaining your balance” energy will be larger. In either case, the “maintaining your balance” energy is necessary. That energy is also a parasitical drain on your energy effort: it doesn’t move the bike forward. A well-run grid is like a good bicyclist on a smooth road. Rotating electric machinery puts VARs on the grid, and if the entire grid was thermal (nuclear, gas, coal) and hydro units, there would rarely be a problem with VARs. These systems all run with rotating electric machinery. But wind turbines and solar make direct current that needs to be changed into alternating current, and that process does not put VARs on the grid in the same fashion. (Some older and bigger wind turbines do put VARs on the grid.) Messing up the VARs can also mess up the grid, so this is another place where the BA must be aware of what is happening on the grid.”
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