The control of the SVC can be assumed as a PI controller
that regulates the firing angle of the thyristors of the thyristor
controlled reactor (TCR). In this case it is assumed that the
available capacitance and inductance of the SVC has the same
rating, and that the inductance can be controlled to zero reactive
current. The simple control structure assumed for the SVC for
determining the firing angle , and by that the resulting shunt
impedance of the SVC is showed in Fig. 3(b).
Both the STATCOM and SVC are controlled so as to obtain
1 pu rated grid voltage before and after the fault. During and immediately
after the fault, the compensating device will be controlled
to its limits so as to give the maximum reactive compensation
possible within the specified ratings.