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I've been reading up on power transmission networks and came across this thing. http://en.wikipedia.org/wiki/Quadrature_booster

Basically it balances the load between two parallel power lines by fiddling with the phase angle of the voltage of one line. What I don't understand (referring to this image: http://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Quad_booster.svg/875px-Quad_booster.svg.png) is this: Does changing the phase angle of the voltage on one of the lines between 'A' and 'B' not mean the Substation B will be presented with power coming from two lines which are not in sync with each other, and will this not adversely affect power quality/cause strange harmonics etc.?

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"Stange" harmonics cannot appear. Two 50Hz sinus waves always produce another 50Hz sinus wave : $$cos(\omega t)+cos(\omega t+\phi)=2cos(\omega t+\frac{\phi}{2})cos(\frac{\phi}{2}) $$

About synchronization, you should remember that the voltage in the network is fixed, and thus only the current changes. I don't see any problem with combining two different currents. In practice, it will change the repartition of power between the lines. Do you see a problem if you connect a resistance in parallel with a resistance and a inductor ?

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  • $\begingroup$ Thank you. Makes sense, of course. If two 50 Hz sine waves always combine to produce another 50 Hz sine wave, then why is it necessary to synchronise generators before bringing them online? $\endgroup$
    – Rónán Kernan
    Commented Nov 24, 2014 at 16:59
  • $\begingroup$ @RónánKernan You should make the difference between passive elements and active ones. For large generators, the question is about the inertia. The voltage is fixed by the network, but also by the position of the rotor, so when the rotor try to synchronize with the network by itself, violent phenomena might occur... Your device is only changing the reluctance of one ligne (see the transport capacity of a power line french only) $\endgroup$
    – TZDZ
    Commented Nov 25, 2014 at 7:30
  • $\begingroup$ @RónánKernan You're free to select the answer ;) $\endgroup$
    – TZDZ
    Commented Dec 9, 2014 at 7:37

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