Voltage control on a transmission line can be achieved by adjusting the off-nominal turns ratio ("tap") of tap-changing transformers at the sending and receiving ends, which alters the voltage magnitude injected onto the line independent of the source voltage, complementing reactive power compensation (static or rotating) as a means of maintaining acceptable voltage profiles under varying load. Related mechanisms include regulating transformers that inject an in-phase (boost/buck) voltage to control magnitude or a quadrature-phase voltage to shift the power angle and thereby control real power flow, since real power transfer on a line is governed by the sine of the angular difference between sending- and receiving-end voltages. This belongs to power system analysis, specifically the study of steady-state transmission line voltage and power flow control, complementary to reactive power compensation techniques.
Voltage control on a transmission line can be achieved by adjusting the off-nominal turns ratio ("tap") of tap-changing transformers at the sending and receiving ends, which alters the voltage magnit…