How do power grids work? How will they be re-shaped by renewables? This 20-page note outlines the underpinnings of electricity markets, from theoretical physics through to looming shortages of ‘inertia’ and ‘reactive power’. Some commentators may not have fully grasped the challenges of back-stopping renewables and opportunities thus created.
The purpose of this note is to outline how power grids actually work. Amazon.com sells two introductory electronics textbooks. But they weigh in at 544-pages and 1,056-pages, respectively. We are going to try to run through the important ideas in about twenty, for the reasons outlined on page 2.
The fundamentals of electromagnetism are covered on page 3, and important concepts are explained from first principles, as clearly as possible.
The fundamentals of electrical power, including key units of measurement, are covered on pages 4-5, again introducing the key concepts from first principles.
Conventional power turbines are described on pages 6-7, including how they synchronize and supply crucial inertia and reactive power.
Solar generation is described on pages 8-9, including the physics of bandgaps, and the electronics of MPPTs and inverters.
Wind generation is described on pages 10-11, including the physics of swept areas, and the electronics of DFIGs and AC-DC-AC converters.
Power distribution and transformers are described on pages 12-14, covering the growing trend towards smaller and more fragmented power distribution.
Power-consuming technologies are described on pages 15-17, explaining how induction motors, resistive heaters, lighting and electro-chemical cells regulate their power consumption.
The crucial debate is over the optimal share of renewables. Our most noteworthy data-points and conclusions are spelled out on pages 18-21.
Overall, the power grid is somewhat reminiscent of Christopher Nolan’s 2020 science fiction thriller, Tenet. Nobody understands it. Tracing a causal chain of events requires looking forwards and backwards in time simultaneously. Someone is hiding in a wind turbine. And the protagonists insist they are working to avert the end of the world.