50/60 Hertz – Primitive Communications

::: nBlog :::

Today’s electrical grids are based on 50 or 60 Hertz alternating current (AC) in three phases, 60 degrees apart. This makes generators with rotating permanent magnets and three coils in symmetric positions quite durable and easy to engineer. A fixed speed electric motor at the receiving end is equally simple – the grid provides automatic timing, while different speeds can be implemented with mechanical gearboxes or frequency converters.

For almost 100 years, frequency of the grid has also been used as a control mechanism for balancing generation and demand. When demand increases, generators need more physical power and their rotation slows down, unless more generating capacity is added to the grid.

Before advanced communications, this frequency control was a very cost effective method for building and maintaining the grid. Each generating source (still) has a programmable logic controller (PLC) based frequency monitoring unit that ties and unties the source from the grid based on below 1Hz frequency changes.

However, this autonomous control mechanism has a few increasingly serious downsides when grids grow large and complex. The frequency highway operates at the speed of light as everything is synchronized – meaning that major events, like power line failures caused by storms, quickly propagate thru the grid in a wavelike domino pattern. Losing a two gigawatt nuclear power plant easily causes hundreds of smaller transmission lines to be automatically tripped off due to a sudden frequency drop. When the said plant is ready for operations again, it will take several hours to stabilize the grid so that the frequency doesn’t exceed the high limit and cause another tripping spree.

I see that it is about time to get rid of the frequency monopoly. We don’t need to go to all direct current (DC) as Nikola Tesla originally proposed (would have to replace far too many AC devices) but we could easily compartmentalize the grid with DC connections between different areas – DC (HVDC) is more efficient in transmission anyway. More importantly, balancing these, even small community size ‘grid cells’ would happen with fiber optic IPv6 networks built in conjunction with the power lines. All cells would have a floating frequency, and they’d be stabilized with small local adjustments, including temporary storage and distributed, small scale generation.

The management and monitoring system of this new ‘grid of islands’ must naturally be inherently distributed, scalable and fault tolerant. And continuously developed along the grid itself.

//Pasi