IEEE Power & Energy Magazine - May/June 2019 - 20

guest editorial

Brian Johnson

new trends for HVdc
an evolution of applications since 2007

This issue of IEEE PowEr &
Energy Magazine covers a range of topics showing new trends in dc transmission applications. The articles build on
the topics introduced in two dc-themed
issues of the magazine in March/April
2007 and November/December 2012,
which provided a snapshot of the state
of development of high-voltage dc
(hVdc) systems around the world at the
time. This issue will do likewise.
The 2007 issue started with a brief history of hVdc. Another article presented
an overview of line-commutated converter (LCC) hVdc schemes and the then-relatively-new voltage-sourced converter
(VsC) hVdc schemes. Common topologies for point-to-point or back-to-back
hVdc schemes were also examined. one
article also gave a history of the development of the Pacific hVdc intertie; another
discussed the planning studies that led to
the implementation of hVdc schemes in
eastern North America. The issue also
contained an article describing the development of ±800-kV ultra-hVdc systems.
The 2012 issue provided an update
on the state of the technology's development. Two articles discussed different
aspects of the growing applications for
hVdc transmission for the integration of
renewables. There were also articles that
described low- and medium-voltage dc
applications for building power systems,
data centers, shipboard power systems,
and dc microgrid applications.
The number of new proposals and
installations for hVdc transmission systems has grown rapidly since those earDigital object Identifier 10.1109/MPE.2019.2896687
Date of publication: 17 April 2019

ieee power & energy magazine

lier issues came out. The application of
±800-kV technology has progressed from
a proposed concept in 2007 to installation
in many locations, such as China, india,
and south Africa. VsC hVdc applications have grown significantly in the past
several years, with modular multilevel
converter-based VsC converters allowing operation at ever-increasing voltage
levels at conversion efficiencies competitive with those of LCCs coupled with the
controllability of VsCs.
interest in multiterminal hVdc
schemes has also grown, driven, in part,
by the desire to bring renewables from
remote locations to population centers
by using underground transmission. This
has pushed the development of circuit
breakers, as will be discussed, and dc/dc
converters that interface existing dc lines
with dc grids operating at different voltage levels. The number of publications
related to hVdc at ieee conferences and
in ieee journals has risen dramatically
in the last 20 years as researchers around
the world have been drawn to the excitement in this growing field.

In This Issue
The authors in this issue present perspectives from consultants, owners, manufacturers, and universities. The articles build
on the topics introduced in the previous
dc-themed issues, and they cover a variety of topics including current trends in
technologies and applications, the current technology of simulation tools for
feasibility and operational studies, and
cybersecurity and resilience.
✔ "high-Voltage dc Conversion" discusses ac-to-dc line conversion as
a solution to eliminate transmis-

sion bottlenecks through the optimized use of existing assets. The
article provides an overview of
potential configurations and then
presents the technical challenges
with ac-to-dc conversion, including key points to consider when
undertaking such a project. An approach for ranking conversion
options is included.
✔ "Current Trends in dc" provides a
view on the drives and timelines
for evolving trends in hVdc and
medium-voltage dc applications.
VsC technologies, which were relatively new in the 2007 issue, are
a central consideration in many
classes of projects. The article discusses the progress made toward
true dc grids and the technology
guidelines in place to make new
projects able to connect with grids
in the future. several new projects that illustrate these trends
are also described.
✔ "improving Grid Resilience using
high-Voltage dc" discusses how
hVdc systems can improve the resilience of the ac systems within
which they are embedded because
of the fast control response. The
authors detail how the controls and
their associated communications
introduce potential cybersecurity
vulnerabilities. The article follows
this topic by describing physicsbased approaches for improving the
resilience of the hVdc controls to
further enable them to enhance the
resilience of the power grid.
✔ "suppor ting energy Transition in Transmission systems"
may/june 2019

IEEE Power & Energy Magazine - May/June 2019

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2019