IEEE Power & Energy Magazine - November/December 2017 - 105

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Harness renewable
energy with Siemens
A large generator of renewable energy calls
for expert support from Siemens PTI

usa.siemens.com/pti-consulting

Generation curtailment risk
assessments
Electric power systems are required
to supply energy with high reliability
at a cost effective price and in a
sustainable manner. Balancing these
requirements is difficult, and has
always relied on extensive study
of complex and sophisticated
power generation, transmission
and distribution infrastructure.
Variability of wind and lack of
correlation with electricity demand
raises challenges for the integration
of large amounts of wind generation
into the power system.
A competitive wholesale power
generator that operates a portfolio
of renewable energy facilities in the
United States was seeking expert
support to assess the possibility of
curtailment on a wind project.
The challenge
Curtailment of generation is a
common challenge for wind and
solar generators, given the resulting
potential for significant loss in
revenue. System Operator-induced
curtailment is typically necessary
to reduce line flows such that
overloads will not occur under outage
conditions; that is to maintain a
dispatch that is secure in both the
existing conditions and under
potential contingency conditions.

With a number of projects already
operating and several more planned,
our client required expert analyses
to identify potential situations that
could lead to curtailments of the
delivery of electric power from an
existing wind resource portfolio to
the ISO's transmission system and
control area. The analyses of
considered the potential transmission system loading issues
related to the changing mix and
location of renewable resources.
Analyses performed by the
Siemens PTI Team
Siemens PTI assembled a team to
provide a comprehensive Generation
Curtailment Risk Assessment for
our client for the wind project in
question. The study evaluated the
transmission system under a variety
of conditions in the near-term and
long-term, representative of the
planning horizon. The analysis
included evaluation of severe system
disturbances using steady state
simulations to identify potential
curtailment situations. The overall
focus was to study the behavior of
the transmission system in which
the wind farm is connected to, and
when in service. In order to better
assess the potential situations that
could lead to curtailments of
the wind farm, the ISO market

operations and its procedures and
business guidelines were also considered in the analysis. Furthermore,
a Market Analysis was performed in
order to simulate the Day-Ahead,
Operating Reserve and Transmission
Congestion Rights Markets.
Recommendations and results
The study results showed that N-1
contingency conditions did not have
any curtailment impact in any of the
study time periods. Other than the
lines that are the more immediate
connections for the wind farm, the
N-2 curtailment risk was considered
to be quite low, even though the
events may be major, because the
probability of their occurrence was
so low. Further-more, the Market
Analysis also showed no significant
curtailment related to the market
conditions simulated in the analysis.
The transmission system near the
wind farm studied is strong, leading
to very limited local congestion and
therefore very limited wind
curtailment.
Interested in learning more?
For additional information on how
your organization can benefit from
Siemens PTI's consulting solutions
for power system planning and
operation, please contact us at
pti-consulting.ptd@siemens.com
or +1 518 395 5000.
http://usa.siemens.com/pti-consulting
Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - November/December 2017
