IEEE Power & Energy Magazine - May/June 2019 - 93

Kangbao
1,500 MW

Fengning
dc
1,500 MW
Breaker

dc
Breaker

ac
500 kV

227 km

dc
Breaker

dc
Breaker
66 km

126 km
Beijing
dc
3,000 MW
Breaker

dc
Zhangbei
3,000 MW Breaker

ac
500 kV

219 km
dc
Breaker

dc
Breaker

figure 10. A diagram of the Zhangbei four-terminal HVdc grid with dc CBs.
WF: wind farm.

DC CB Installed in the Zhangbei HVdc Grid
Due to its geographical advantage, the Zhangbei region of
northern china has seen considerable development of projects for harnessing wind energy. the development of wind
projects is expected to continue at least into 2020. however,
the task of successfully integrating these resources presents
challenges, because the wind farms are located some distance
from where the power is consumed and because wind and,
thus, energy generation are intermittent and highly variable.
many of these concerns can be addressed with the implementation of hVdc networks equipped with hVdc cBs. thus, a
±500-kV, 3,000-mw four-terminal hVdc grid project has
been proposed.
the project adopts a four-terminal ring, and the operating
configuration is a bipolar topology with a metallic return line
(Figure 10). the Zhangbei and Kangbao converter stations
are the sending terminals collecting local wind power. the
Fengning converter station is a regulating terminal connected
to a local pumped-storage hydroplant, which can even out
the fluctuations in the production of wind power. the Beijing

may/june 2019

Acknowledgment
the work for this article was
funded in part by the national
Key r&D program of china
(2017yFB0902400).

ac
ac
500 kV 1,000 kV

the hV silicon rectifier D c, where the resistor R c is used to
limit the inrush current during the charging process.
compa red to convent iona l mechanical dc cBs, this
mechanical hVdc cB is less costly and more compact
thanks to its air-core coupling reactor and smaller key
components in the injection branch. experimental results
show that the mechanical hVdc cB successfully interrupted a 9.2-ka fault current, with peak tiV reaching 272 kV
in 3.9 ms.

converter station is the receiving terminal used to supply renewable power for Beijing.
the Zhangbei project adopts
a half-bridge modular multilevel
technology and uses overhead
lines. as a result, dc breakers
must be installed at both ends
of the line to clear potential dc
faults, such as those induced by
lightning. a 500-kV dc breaker
prototype was developed in 2018,
and the project is scheduled for
operation in 2020.

For Further Reading

D. Jovcic and K. ahmed, High
Voltage Direct Current Transmission: Converters, Systems and DC Grids. hoboken, nJ:
wiley, 2015.
J. häfner and B. Jacobson, "proactive hybrid hVDc
breakers-a key innovation for reliable hVDc grids,"
presented at the cigré 2011 Bologna Symp., Bologna,
italy.
K. tahata et al., "hVDc circuit breakers for hVDc grid
applications," in Proc. IET Int. Conf. on AC and DC Power
Transmission, Birmingham, u.K.: Feb. 2015. doi: 10.1049/
cp.2015.0018.
G. tang, Z. he, h. pang, X. huang, and X. Zhang, "Basic
topology and key devices of the five-terminal Dc grid," CSEE
J. Power Energy Syst., vol. 1, no. 2, pp. 22-35, June 2015.
G. tang, X wei, and w Zhou, "research and development of a full-bridge cascaded hybrid hVDc breaker for
VSc-hVDc applications," in Proc. Cigré 2016 Sess., paris,
paper a3-117.
progress on meshed hVDc offshore transmission networks. accessed on: 2018. [online]. available: https://www
.promotion-offshore.net/

Biographies
Dragan Jovcic is with the aberdeen hVDc research centre at the university of aberdeen, united Kingdom.
Guangfu Tang is with the Global energy interconnection research institute of the State Grid corporation of
china.
Hui Pang is with the Global energy interconnection research institute of the State Grid corporation of china.
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