IEEE Power & Energy Magazine - July/August 2019 - 25

Shaping the Electric
Power Grid of Korea
The green substation provides a platform to support the increase of renewable energy (RE) as
well as demonstrate the achievement of environment-friendly substations by reducing the production of air pollutants, such as sulfur hexafluoride (SF6) gas. For example, since 2016, the 23-kV
gas-insulated switchgears (GISs) with SF6, used for more than 20 years in the Korean electric
power grid, are being replaced by GISs with dry air and solid-insulated switchgears (SISs). A
modular green substation is proposed for interconnecting the increasing amounts of RE. This
example of the future green substation will play an important role in integrating remotely located
RE sources (RESs) into the power grid.
The expanded adoption of distributed energy resources (DERs) changes the grid dynamics by
displacing the large fossil fuel and synchronous generators, thereby weakening the grid strength,
requiring new capabilities and functionalities for the future substations. The fundamental changes
and opportunities of the future power system with improved reliability, availability, efficiency, and
security can be summarized as follows:
✔ the high penetration of DERs
✔ the high integration of controllable devices for power system support
✔ the interconnection of power systems in different countries and regions via a dc grid (or
supergrid)
✔ the convergence of IT, automation, and power engineering
✔ the advanced control and protection schemes
✔ the communication networks in power systems.
With these priorities in mind, various projects, such as communication network development
for digital substations, modular green substations for increasing the hosting capacity of RESs,
online load modeling for reliable power system operation, phasor-measurement unit (PMU) data
acquisition and analysis systems, and the Jeju Island testbed for the smart grid, have been undertaken in the Republic of Korea. The following sections will introduce these efforts for future
smart and green substations to shape the electric power grid of the Republic of Korea.

Overview of the Korean Electric Power System
Brief History of Its Electric Power Industry
In 1887, the first light bulb was illuminated at the royal palace in Seoul. Over the last 130
years, Korea's electric power industry has grown dramatically. KEPCO was established with
the Electricity Enterprises Act (three electric companies were merged and became a wholly
government-owned corporation) in 1961. KEPCO is the only electric utility company that owns
the transmission and distribution system in the Republic of Korea. The overall power demand
in the country has grown significantly since the 1970s due to industrialization and rapid economic growth. The maximum demand was 5.4 GW in 1980 and 41 GW in 2000, and the highest
demand was 92.5 GW in 2018. The peak demand has increased by more than 17 times over the
past 38 years.
The fi rst high-voltage (HV) dc interconnection between Jeju Island and the main peninsula
was completed in 1998. The purpose of the HVdc installation was to improve the reliability of
the power system of Jeju, the biggest island in the Republic of Korea, and to reduce the cost of
its electricity.

Korea Electric Power Substation Statistics
The Republic of Korea is currently one of the largest consumers of electrical energy in the
world, due to the country's rapid economic growth of heavy and chemical industries. The
Republic of Korea consumed a total of 507.7 TWh of net electricity in 2017, with 276.6 TWh
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