The PI controller (PI cont.) controls reactive voltage
part ([u.sub.d]) to zero value by signal [DELTA][omega] correction.
When using the reactive voltage
regulation capability of PV, the maintenance cost should be taken into consideration:
A SSSC operated without an external Electric Energy source as a Series compensator whose output Voltage is in quadrature with, and controllable independently of, the line current for the purpose of increasing or decreasing the overall reactive Voltage
drop across the line and thereby controlling the transmitted active power.
 Wang Ke, Wang Le, "Improved sequential quadratic programming algorithm of reactive voltage
optimization", in Proc.