IEEE Power & Energy Magazine - May/June 2019 - 66

tools are more appropriate for studying the detailed charac-
teristics of power electronic components. the utilization of
e-trAn enables the conversion of tsA files into emt files
reflecting the power system's dynamic model information
for components such as generators, transmission lines, and
loads. detailed modeling of the hVdc scheme, stAtComs,
and tCsCs provides the ability to thoroughly observe
the dynamic behavior of each device. the time and effort
required to build a case study for accurately representing such
characteristics are significantly greater than those for tsA
cases. in addition, the computation burden is much larger
than that in tsA, which makes emt tools inefficient when
simulating large power systems and conducting system-wide
impact studies. therefore, network equivalents represent por-
tions of the system electrically far from the hVdc converter
terminals. however, this use of equivalent circuits weakens
the accuracy of the results. Both tsA and emt approaches
have their own strengths and weaknesses as well, which leads
to research opportunities to combine their strengths.
kepCo invested in developing real-time simulation
(rts) cases of the entire korean power system. detailed
rts models of each component in the power system were
used to verify all of the influences from various hVdc operat-
ing modes. however, because of its complicated nature and
the difficulty in making changes to the entire network as
compared with those possible with tsA tools, kepCo inves-
tigated the concept of cosimulation or hybrid simulation that
combines the detailed modeling available in emt packages

Border of
Load Center

345 kV
765 kV
Planned 765 kV
HVdc
TCSC

Coal Plant
(2 GW)

with the bulk power system simulation of tsA tools while
compensating for the weaknesses of both tsA and emt.

Jeju: Toward a Zero-Carbon Island
A serious concern for kepCo planners is the difficulty
in performing accurate power system analysis with the
increased use of power converters with hVdc and fACts.
the problem of choosing an appropriate simulation tool has
arisen again with the Jeju hVdc number 3 project. Jeju island
is the largest island in korea, and it connects to the mainland
through hVdc lines, as shown in figure 5. the Jeju electric
power system has different characteristics as compared with
the republic of korea mainland power system. Because of
the abundant renewable energy sources, the Jeju special self-
governing body declared a vision of becoming a carbon-free
island by 2030.
the multi-infeed hVdc system presently in operation
has had two lCC-hVdc lines (hVdc number l is 300 mw
and hVdc number 2 is 400 mw) since 2010. the renewable
power capacity on the island was 380 mw in 2017, and the
republic of korea government aims to install further renew-
able energy sources totaling approximately 2 gw on Jeju by
2030. Although there are eight synchronous generators, three
or four are typically in service, with minimal power genera-
tion during the off-peak load condition to support the mini-
mum scr required by the lCC-hVdc converters. the peak
load of Jeju was approximately 930 mw in 2017. in the future,
when Jeju's wind power penetration surpasses its peak load,

Coal Plant Coal Plant
(2 GW)
(2 GW)

Nuclear Plant
(2 GW)

STATCOM
Nuclear Plant
(2 GW)

Nuclear Plant
(2 GW)

Nuclear Plant
(6 GW)

figure 4. A simplified network from the generation complex to the Seoul metropolitan area with HVdc and FACTS. The
single transmission lines above are double-circuit lines.
66

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