Thursday, 15 September 2016

Do we want brownouts?

The normal mains voltage in UK is 230V. But there is an acceptable range which is legally defined as +10% -6%, i.e. the voltage can range from a maximum of 253V to a minimum of 216V.

It is sometimes suggested that the power supplied to the grid could be limited by using some of this range.

If we had a simple system (which we do not!) where the voltage was the same at all supply points, we could theoretically reduce consumption by up to 37% by reducing the voltage from 253 to 216

In practice the available range is very much smaller, and is reduced further by local intermittent renewable generation. Anecdotally, when my PV system is at full output and I switch off all loads, my voltage rises to about 250V, near the maximum.

Nonetheless, a few percent of power reduction is available.

For example, reducing voltage at peak demand times in winter from 230V to 223V would result in a peak power reduction approximately equal to that of a Hinkley sized power station. It would give no noticeable dimming of lights or other unwanted results.

We wouldn't of course need to even think about this if we all avoided unnecessary consumption at peak times in winter!