  The problem of regulating voltages within the required limits is complicated
by the fact that power system supplies power to a vast number of loads and is
fed from many generating units. As loads vary, reactive power requirements of
the transmission system vary. Moreover, voltage magnitude is relatively less
sensitive to active power compared to reactive power due to high X/R ratio of
transmission lines. Therefore, separating voltage control from active power is
not only justified but also the common and practical way in power transmission
systems. Considering these facts, the fast decoupled power flow jacobian can be
used to control voltage magnitudes by reactive power compensation. In this
paper, an optimal voltage control is presented to obtain new voltage set-points
for PV buses by maximizing the effect of input change on output change using
the Fast Decoupled Load Flow (FDLF) jacobian matrix. The proposed algorithm was
tested on three IEEE systems: 9 bus, 14 bus and 30 bus systems.
