The contributor from Isle of Man that I would never challenge on technical issues pointed out to me that current can be injected into the grid by shifting the phase rather than raising the voltage, and I was confusing myself considering DC theory rather than AC.

I believe that with DC the voltage has to be raised, as in battery charging, but with AC the voltage doesn’t have to be raised as the phase can be shifted.

Please don’t ask me to explain it!

well a 180 degree phase shift is pushing instead of pulling, i.e. a load-source reversal. Other phase shifts can be seen as reactive power - or a mix of reactive and either generation or dissipation..
You can use an inverter that supports bi directional power flow(*) by driving ts generating voltage out of phase with the mains to emulate the action of a capacitor or an inductor, or more commonly a generator with some extra capacitance or inductance in parallel. Such 'reactive power' can be used to tame some power factor issues. It is not as cheap as fixed capacitors, but it is programmable.

Mike.

(* )so power goes from the dc bus, battery or whatever out onto the mains for some of the cycle period, but then for the rest  of the cycle current flows back from the mains to recharge the DC bus. - a pure capacitor, or inductor averaged over the full cycle, adds nothing to the power, just time shifts it...

well a 180 degree phase shift is pushing instead of pulling, i.e. a load-source reversal. Other phase shifts can be seen as reactive power - or a mix of reactive and either generation or dissipation..
You can use an inverter that supports bi directional power flow(*) by driving ts generating voltage out of phase with the mains to emulate the action of a capacitor or an inductor, or more commonly a generator with some extra capacitance or inductance in parallel. Such 'reactive power' can be used to tame some power factor issues. It is not as cheap as fixed capacitors, but it is programmable.

Mike.

(* )so power goes from the dc bus, battery or whatever out onto the mains for some of the cycle period, but then for the rest  of the cycle current flows back from the mains to recharge the DC bus. - a pure capacitor, or inductor averaged over the full cycle, adds nothing to the power, just time shifts it...

mapj1 said:

Such 'reactive power' can be used to tame some power factor issues. It is not as cheap as fixed capacitors, but it is programmable.

...and, side note, is sometimes stipulated by DNOs (e.g. where they specify generation at the point of supply shall be at a specific power factor other than unity).