Coronal Mass Ejections (CME), which originate from active regions of the Sun’s surface, e.g., sunspots, result in geomagnetic storms on Earth. The variation of the Earth’s geomagnetic field during such storms induces surface currents that could cause breakdowns in electricity power grids. Hence, it is essential to both monitor Geomagnetically Induced Currents (GICs) in real time and analyze previous GIC data. In 2012, in order to monitor the variation of GICs, the Korean Space Weather Center (KSWC) installed an induced current measurement system at SINGAPYEONG Substation, which is equipped with 765 kV extra-high-voltage transformers. Furthermore, in 2014, two induced current measurement systems were installed on the 345 kV high-voltage transformers at the MIGEUM and SINPOCHEON substations. This paper reports the installation process of the induced current measurement systems at these three substations. Furthermore, it presents the results of both an analysis performed using GIC data measured at the SINGAPYEONG Substation during periods of geomagnetic storms from July 2013 through April 2015 and the comparison between the obtained GIC data and magnetic field variation (dH/dt) data measured at the Icheon geomagnetic observatory.

1. INTRODUCTION
 2. INSTALLATION OF INDUCED CURRENTMEASUREMENT SYSTEM
  2.1 Induced Current Measurement System
  2.2 Installation of Induced Current Measurement Systemat the Three Substations
 3. ANALYSIS OF INDUCED CURRENT ANDGEOMAGNETIC VARIATION DURING PERIODSOF GEOMAGNETIC STORMS
  3.1 Selection of Geomagnetic Storm Events
  3.2 Analysis
 4. CONCLUSIONS
 ACKNOWLEDGMENTS
 REFERENCES

• Kyu-Cheol Choi(Research Institute, SELab, Seoul 06049, Korea) Corresponding Author
• Mi-Young Park(Research Institute, SELab, Seoul 06049, Korea)
• Youngsoo Ryu(Research Institute, SELab, Seoul 06049, Korea)
• Youngsu Hong(Research Institute, SELab, Seoul 06049, Korea)
• Jong-Hyuk Yi(Research Institute, SELab, Seoul 06049, Korea)
• Sung-Won Park(Korean Space Weather Center, National Radio Research Agency, Jeju 63025, Korea)
• Jae-Hun Kim(Korean Space Weather Center, National Radio Research Agency, Jeju 63025, Korea)