±100(200)MVA STATCOM was installed at the 345kV Migum substation owned by the Korea Electric Power Company (KEPCO) on August 2009 and has been contributing to greater power stability of the transmission grid. ±100(200)MVA STATCOM eases the power circuit alternation and utilized the improved 3-level pole inverter in order to solidify the arrangement. The pole structure was designed as a module form. it is operating with an availability of 99.49%. Each pole has a 4 IGCT value and each IGCT valve is composed of a series of 8 connected IGCTs.
Pulse Number: 24
No. of Pole: 6
No. of Modules per Valve: 8
Nominal DC Bus Voltage (± to mid point): 10,000
Nominal Pole Output Voltage V (ph-n) rms: 8,926

±10(20)MVA STATCOM was installed with a goal of preventing voltage fluctuations and improving power quality for Hyosung Changwon Plant’s 22.9kV distribution grid on March 2007. In 2008, it was operating with an availability of 98.07%.
Inverter rating: ±10(20)MVA
Pulse number: 24
No. of poles: 6
No. of modules per valve: 1
Nominal DC bus voltage: 2,000
Nominal Pole Output Voltage V (ph-n) rms: 1,786

UPFC is one of FACTS devices using high-capacity voltage source inverter. UPFC controls the power flow by connecting 2 inverters to a power transmission line in serial / parallel manner.
- Through technical alliance with Siemens of USA, 154kV / 80MVA, UPFC was installed in the Gangjin substation and now in operation, for the first time in Korea.
-Connected to 154kV and 345kV high-voltage power transmission system using GTO Thyristor element.
-Independent control of active power, reactive power and terminal voltage of transmission line where UPFC is connected can increase power transmission capacity through maximum use of existing transmission lines.
- Speedy compensation function realized by swift control time in an accident or overload status, which is not available in the existing phase modifying equipment, contributes to the stabilization of a power transmission system.
-Modularized GTO valve enables easy maintenance

Through technical alliance with Siemens of USA, 22.9kV / ±1(2)MVA, DSTATCOM was installed in a Haman substation and is now in operation, for the first time in Korea.
Key functions
-Mitigation of voltage flicker
-Compensation for change in load-end voltage and harmonics
-Improvement of power factor
Effect from installation
-Preventing influence of malignant load in factory on neighbor around distribution system.
-Improved utilization of lines
-Stabilized power supply and improved system efficiency