STATCOM Principle [Inductive mode] If Vstatcom is lower than V, the inductive current flows from the AC system to the converter [Capacitive mode] If Vstatcom is higher than V, the capacitive current flows from the converter to the AC system I leading V V V V I V Functions of Transmission Line I V lagging ?Voltage Stability ?Enhancement of Transmission Capability V V ? statcom statcom Improvement of Transient Stability V statcom VSC Inductive Mode Capacitive Mode Characteristics STATCOM can be operated in two different modes: System - In voltage regulation mode Voltage SVC (The voltage is regulated within limits as explained below) 1.0 - In VAR control mode 0.9 (STATCOM reactive power output is kept constant) 0.8 0.7 When STATCOM is operated in voltage regulation mode, 0.6 it implements the following V-I characteristic. 0.5 STATCOM STATCOM can be operated over its full output current range 0.4 0.3 even at very low system voltage levels. 0.2 In other words, the maximum capacitive or inductive output 0.1 current of STATCOM can be maintained independently of the IC 0 IL AC system voltage, and the maximum VAR generation or absorption changes linearly with the ac system voltage. I 06 07 STATCOM STATic Synchronous COMpensator