[time-nuts] A Research Proposal

[Bill Hawkins]

Um, you're quite right that DC lines have no phase angle - unless you call a polarity reversal a 180 degree shift.

I was referring to the phase angle of the AC side of an inverter with respect to the average phase angle of the grid that it is connected to. 
It behaves just like a synchronous machine.  Advance the phase angle of the inverter and it pumps energy into the grid. 
The inverter at the other end of the DC line must be lagging in order to take power from that grid.
Conservation of energy says you must take more power than you deliver in order to cover the resistive and corona losses in the DC line and the conversion losses in the inverters.

Perhaps the source inverter phase angle is controlled by the DC output voltage, and the load phase angle is controlled by the DC current.  Controlling the load inverter phase angle would be like adjusting the steam to a turbine coupled to a generator.  I have no knowledge of how control is actually accomplished.

Bill Hawkins

On Mon, Jul 8, 2019, at 6:12 AM, Hal Murray wrote:
> 
> bill.iaxs at pobox.com said:
> > Since the direction of power flow depends on the phase angle between the
> > synchronous source and load, it seems to me that the difference between the
> > average phase angle in one region and that in another (at the ends of a DC
> > transmission line) will tell you which way power is flowing.
> 
> Nope.  The phase angle difference tells you a lot on an AC line, but nothing 
> on a DC line.  For DC, the frequencies can even be different.  That means the 
> phase angle is changing, and it can wrap around while the phase angle on an AC 
> system is always small.
> 
> A classic 3 phase synchronous motor is also a generator if you are pushing it 
> rather than it is pushing you.  The sign of the phase angle flips between 
> motor and generator.  In this context, the phase angle is the angle the 
> magnetic lines make between the rotor and stator.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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