IEEE Electrification - March 2022 - 64

synchronous generator from the grid during the first
half cycle of the pole slipping can avoid damage.
All of these measures are practical and low-cost solutions
to keep the grid strong and stable compared to other
measures that can be used in IBR-dominated grids, such
as oversizing inverters or deploying synchronous condensers.
In fact, Type-5 technology already provides all of
these as natural behaviors with no controls and no additional
cost.
Conclusions
GFM technology for IBRs is gaining traction in the energy
industry as the grid continues to evolve with increasing
shares of IBRs and retiring conventional generators.
GFM control by IBRs can replace some of the services
that synchronous generators have been providing.
Mainstream wind power based on Type-3 and Type-4
electric topologies, as an IBR technology, is fully capable
of providing GFM services. Testing and demonstrations
have been conducted for both topologies. Although it is
not yet commercially available (like GFM battery storage),
GFM wind can make a quick market entry when
required. There are still several aspects related to controls
and design improvements of GFM wind is actively
being developed by wind turbine manufacturers that
the industry can address when there is a market in
place to incentivize the provision of such services. The
stabilizing impacts of GFM controls for IBRs have been
demonstrated in many studies. This study demonstrated
the stabilizing impacts of GFM wind, in particular.
Despite many stabilizing characteristics of GFM IBRs as
an enabler for the future carbon-free renewable grid,
GFM alone is not a sufficient measurement to resolve
all the integration challenges described in this article,
with the issue of degrading grid strength and the consequent
reduction in the fault current levels being the primary
challenge. The substantial deployment of other
enabling technologies, such as synchronous condensers,
might be necessary to keep the grid strength within
acceptable limits. From this perspective, wind power
offers a unique solution in the form of Type-5 wind turbine
topologies to address essentially all grid integration
problems by keeping the grid largely synchronous
at very high penetration levels (potentially up to 100%)
of renewable generation.
The advantages of the Type-5 technology were
described in this article, and certain design aspects (largely
mechanical) might need further study and improvement
for Type-5 wind power. It might be up to the
mechanical and structural engineering community " to
save " the grid because the electric and power systems
engineering aspects of synchronous generation-based
operation are well understood and conventional. Does this
mean that we recommend that every wind power plant
on the grid must become Type 5? Probably not, unless it
proves to be significantly more cost-effective. In any event,
64
IEEE Electrification Magazine / MARCH 2022
the Type-5 technology, if commercially available, can be
deployed at adequate capacities on the grid to maintain
and enhance grid stability, especially in weaker parts of
the grid. The additional option of being able to operate as a
synchronous condenser during low wind means that this
technology can be an enabler for the secure integration of
all IBR resources, including PV and battery energy storage.
Acknowledgments
This work was authored, in part, by the NREL and operated
by Alliance for Sustainable Energy, LLC, for the U.S.
Department of Energy (DOE) under contract number
DEAC36-08GO28308. The funding was provided by the
DOE's Office of Energy Efficiency and the Renewable
Energy Wind Energy Technologies Office. The views
expressed in the article do not necessarily represent the
views of the DOE or the U.S. government. The publisher,
by accepting the article for publication, acknowledges
that the U.S. government retains a nonexclusive, paid-up,
irrevocable, worldwide license to publish or reproduce
the published form of this work, or allow others to do so,
for U.S. government purposes.
For Further Reading
S. Shah and V. Gevorgian, " Control, operation, and stability
characteristics of Grid-Forming Type III wind turbines, " presented
at the 19th Wind Integration Workshop, Dublin, Ireland,
Nov. 11-12, 2020.
X. Wang, M. G. Taul, H. Wu, Y. Liao, F. Blaabjerg, and L.
Harnefors, " Grid-synchronization stability of converter-based
resources: An overview, " IEEE Open J. Ind. Appl., vol. 1, pp. 115-
134, Sep. 2020.
A. Roscoe et al., " Practical experience of operating a GFM
wind park and its response to system events, " presented at
the 18th Wind Integration Workshop, Dublin, Ireland, Oct.
16-18, 2019.
G. Henderson, " The latest development in synchronous
wind turbine topology: How the LVS system can deliver low
cost, broad-band variable turbine speed and Type V grid connection, "
presented at the 20th Wind Integration Workshop,
Berlin, Germany, Sep. 29-30, 2021.
" Research roadmap on grid-forming inverters, " National
Renewable Energy Laboratory, Golden, CO, USA, Tech. Rep.,
Nov. 2020. [Online]. Available: https://www.nrel.gov/docs/
fy21osti/73476.pdf
Biographies
Vahan Gevorgian (vahan.gevorgian@nrel.gov) is with the
National Renewable Energy Laboratory, Golden, Colorado,
80401, USA.
Shahil Shah (shahil.shah@Nrel.gov) is with the
National Renewable Energy Laboratory, Golden, Colorado,
80401, USA.
Weihang Yan (weihang.yan@nrel.gov) is with the
National Renewable Energy Laboratory, Golden, Colorado,
80401, USA.
Geoff Henderson (geoff.henderson@windflow.co.nz) is
with SyncWind Power Ltd, Christchurch, New Zealand.
https://www.nrel.gov/docs/ty21osti/73476.pdf https://www.nrel.gov/docs/ty21osti/73476.pdf
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