General STATCOM(STAtic synchronous COMpensator) is a power electronic device comprised of power inverters to control reactive power into a power system for purpose of controlling system voltage. The semiconductor switching device that overcomes the limitations of conventional mechanical control devices allows for the reduction of reactive power and ensures enhanced stability against system fault. With its advanced VSC(Voltage Source Converter) technology, Hyosung provides the best solutions for improving the overall voltage stability, such as a fast compensation cycle and space saving. Main Function ?Voltage Regulation ?Three-Phase Voltage Balancing ?Power Transfer Capacity Increase ?Reactive Power Compensation ?Transient & Steady State Stability Improvement ?Flicker Suppression ?Power Oscillation Damping Applications Utility Rail-Way ?Improve availability ?Control reactive power and harmonics for power ?Improve available active power supply system ?Suppress voltage fluctuation and flicker ?Improve power quality ?Control voltage unbalance ?Reduce power loss ?Reduce harmonic distortion ?Balance negative sequence current caused by ?Improve power factor and reduce loss of reactive power locomotive load EAF Wind-Farm ?Improve power factor and reduce penalty risk ?Control reactive power at the junction of wind power ?Decrease melting-time and increase available active power plant and power grid ?Reduce reactive power loss ?Reduce the voltage fluctuation caused by power variation during power generation, and stabilize the grid ?Reduce voltage fluctuation and flicker, and increase production efficiency ?Maintain the voltage level in connection point and improve LVRT(low voltage ride through) characteristic ?Reduce harmonic distortion and protect facility ?Balance negative sequence current caused by the electric arc furnace
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