The PMS performs many calculations for determining the
set point changes required by the P/f and Q/V algorithms. The
magnitude of the set point changes will depend on the
difference between the actual state of the power system and
what is should be. Since it is important for system stability to
make changes in a controlled manner, the PMS will only send
a set point change that corresponds at most to 50% of the
calculated total set point change. This is illustrated in Fig. 10.