IEEE Power & Energy Magazine - July/August 2019 - 33

monitoring, diagnosis, and control for the G-platform. The
optimal capacity and type of the G-platform has also been
investigated to increase the hosting capacity of renewables.
The G-platform should play a key role in the future green
Korean power grid.

Toward an SF6 Gas-Free
Ecofriendly Substation
KEPCO is continuously striving to install ecofriendly substation equipment and develop advanced testing and operational technologies. As part of this effort, HV vacuum CBs
(VCBs) have been developed by Korean CB manufacturers
since 2016 and will be deployed in 2021. CB interrupting
capabilities will be rated 50 kA, and the rated steady-state
current will be 3,150 A. Real-time monitoring of the withstand voltage and the mechanical and electrical characteristics of CBs will be implemented to ensure their reliable
condition and to predict breakdowns. By not using SF6 in
CBs, the project aims to reduce use of greenhouse gases
by an equivalent of 300,000 metric tons of CO2 from 2021
through 2030.
An SF6-free ecofriendly GIS with a fluoronitrile/CO2
mixture and an alternative GIS with dry air have been under
development since 2017, including maintenance technologies
and CBs. KEPCO established the standard specification for
an ecofriendly GIS in 2018; the pilot installation of a 170-kV
GIS will begin in 2019 and will be used in new substations by
2021. The goal is to reduce the use of greenhouse gases by an
equivalent of 120,000 metric tons of CO2 from 2021 through
2030 by not using SF6 in GISs. The 23-kV GISs, which have

Metropolitan Area
(Load Center)
Uijeongbu

Seoinchon C/C

been used for more than 20 years in the Korean electric power
grid, are being replaced by GISs with dry air and SISs. Adopting the new CB and GIS technologies will also improve reliability performance. When an ecofriendly VCB and GIS are
successfully developed, more than 100 HV VCBs and GISs
per year will be installed in the Korean power grid, either as
new or replacement installations.

Power Electronics-Based Substation
The development of power electronics-based substations (e.g.,
HVdc and FACTS) has increased significantly during the past
few decades. (Table 4 shows existing and planned HVdc and
FACTS substations in the Republic of Korea.) Most HVdc
ties connect two distinct areas for integrating remote generation, interconnecting grids, and long-distance power transmission. Current HVdc projects in Korea have been chosen as
an alternative to the expansion of the 765-kV ac transmission
system. Public opposition to 765-kV tower construction has
resulted in new HVdc plans for interconnecting the east coast
to the west metropolitan load center because of the relatively
smaller size of the HVdc transmission facilities and fewer
concerns regarding the health effects of HV electromagnetic
waves. Because HVdc and FACTS can provide better controllability of power flow, the installation of HVdc and FACTSs
will improve the stability and security of the power system.
A voltage-sourced back-to-back (BTB) HVdc is planned at
the Yangju substation to control power flows and reduce the
short circuit current in the Seoul metropolitan area, which is
served by a ring network as shown in Figure 8. Here the level
of the short circuit increases as the power system is reinforced

Singapyoung

Yangju

Miguem
Dongseoul

Sininchon C/C

Sinsungnam

Sinsiheung
Power Plant
Substation Without FACTS
Substation With FACTS
Power Flow Direction
BTB

Power Plant
Major Loads
765-kV Line
345-kV Line

figure 8. Substations in the metropolitan area and the location of the BTB HVdc. C/C: combined cycle.
july/august 2019

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IEEE Power & Energy Magazine - July/August 2019

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