Solar Farms.

It is a general problem of DC to AC inversion of the kind that chops the DC. The square edges in effect create a spectrum that looks like a comb of high frequency lines extending over many MHz. Ideally this would be rounded off, with LC filters,  and the raw waveform pre-filters, routed in a way that did not create accidental antennas.

It does not have to be a problem, but the pressures of  "value engineering" means that filtering and RF decoupling only just meets the legal requirements, and that is nothing like enough to protect a small signal service. Radio hams operate much closer to the limit of the noise floor than broadcast and commercial communications - getting the ultimate range for lowest power is something of a competition.

As such solar farms and windfarms are particularly bad, as they are throwing many KA around the place, but I fear the problem will spread, with more DNOs  fitting DC bus links between phases and between substations to prop up the LV network (so far I am aware of trials in  London, but not yet more generally.

The idea is that  a lightly loaded substation can be rectified to create a DC, and then that used to support another phase or shipped to another substation to be re-inverted there.

It need not be an EMC problem, but I fear the commercial pressures mean it will be.


Mike.

It is a general problem of DC to AC inversion of the kind that chops the DC. The square edges in effect create a spectrum that looks like a comb of high frequency lines extending over many MHz. Ideally this would be rounded off, with LC filters,  and the raw waveform pre-filters, routed in a way that did not create accidental antennas.

It does not have to be a problem, but the pressures of  "value engineering" means that filtering and RF decoupling only just meets the legal requirements, and that is nothing like enough to protect a small signal service. Radio hams operate much closer to the limit of the noise floor than broadcast and commercial communications - getting the ultimate range for lowest power is something of a competition.

As such solar farms and windfarms are particularly bad, as they are throwing many KA around the place, but I fear the problem will spread, with more DNOs  fitting DC bus links between phases and between substations to prop up the LV network (so far I am aware of trials in  London, but not yet more generally.

The idea is that  a lightly loaded substation can be rectified to create a DC, and then that used to support another phase or shipped to another substation to be re-inverted there.

It need not be an EMC problem, but I fear the commercial pressures mean it will be.


Mike.