Download Wind Farms without Borders: Top 5 Practices when

FACTS Devices for Dynamic Reactive
Power Compensation in Wind Farms
Piotr Wiczkowski
Sargent & Lundy LLC
Electrical Analytical Division
Abstract
Federal Regulatory Energy Commission (FERC) Order No. 827, which was issued in June 2016 and became effective in September 2016, requires wind farms to provide dynamic reactive power compensation. The ruling was initiated
and justified based on the advancements in Type III and Type IV inverter-based wind turbine generator (WTG) dynamic reactive power supply capabilities. In addition to the WTG’s inherent reactive power capabilities, Flexible AC
Transmission Systems (FACTS) devices such as Static VAR Compensators (SVCs) and Static Compensators (STATCOMs) can be utilized to supplement the wind farms to be in full compliance with the dynamic reactive power
compensation requirements. Today, about 5 % of the FACTS market segment is for renewable projects, and the share is expected to increase in the near future with the FERC ruling. This poster explains key design considerations and
performance requirements for the FACTS devices. Additionally it overviews prudent approaches for project developers and in preparing specifications, performing bid evaluations and executing procurement of Facts Devices.
Methodology
As part of our extensive electric power industry experience, Sargent & Lundy has significant wind energy experience. We have provided a full range of services to the wind energy industry, including site screenings, project feasibility
studies, wind resource assessments, independent engineering, collector interconnection planning, conceptual engineering, contract development, detailed engineering, design reviews, construction monitoring, commissioning, and
operations and maintenance (O&M) support. Sargent & Lundy has worked on wind farm projects for over 15 years. We participate in the AWEA Offshore Wind Working Group and the AWEA Wind Power O&M Working Group. We
also actively participate in the IEEE Wind Plant Collector Design Working Group as well as the High Voltage Power Electronics Working Group.
FERC Order
No. 827
FACTS
Devices
New wind power generation must
maintain a composite power delivery,
at continuous rated power output, at
the high-side of the generator
substation at a power factor within the
range of 0.95 leading to 0.95 lagging.
The power factor range standard shall
be dynamic and can be met using, for
example, power electronics designed to
supply this level of reactive capability
(taking into account any limitations due
to voltage level, real power output,
etc.) or fixed and switched capacitors,
or a combination of the two
Static VAR Compensators (SVC)
• IEEE recommends the Detailed
Functional route.
• IEEE 1031 can be used, even though
it is designed for transmission class
SVCs.
• IEEE is working on a STATCOM
functional specification guide.
• Manufacturers are familiar with the
IEEE guides and it touches on all the
key aspects of specifying an SVC, but
it will still give the manufacturer the
flexibility to choose what they want.
Will give the best in terms of pricing.
Typical Support Studies
Static Synchronous compensator
(STATCOM)
• A flexible alternating current
transmission system (FACTS) is a
system composed of static equipment
used for the AC transmission of
electrical energy. It is meant to
enhance controllability and increase
power transfer capability of the
network. It is generally a power
electronics-based system.
• These devices, in conjunction with
turbine capabilities, enhance dynamic
VAR support
• FACTs devices offer advantages
outside required VAR support
including fault recovery, voltage
support, phase balancing, etc.
Specification and
Procurement
Functional vs. Detailed Functional
vs. Detailed Specification
• A continuously adjustable (dynamic)
admittance, capacitive through
inductive. SCVs can respond quickly
to network changes to
counterbalance the variations of the
load flow or occurrence of faults
• SVCs are thyristor controlled shunt
capacitors and/or reactors
• More typically for higher voltage
transmission applications
• Produces Low Order Harmonics
• Historically lower cost than
STATCOMs
Regional entities, such as ERCOT, may
have stricter requirements. Requiring
0.95 power factor, calculated at a units
maximum power output, available at all
MW output levels
What is a FACTS
Analysis
Requirements
• Voltage source convertor (VSC).
Compromised of a voltage source (DC
Capacitor) behind a reactor.
• Advantages over SVCs include greater
performance at low operating
voltages, faster response time, and
small form factor
• Expensive at higher voltage levels,
typically installed on the collector
system
• Historically more expensive than
SVCs but reaching price parity
• Can be designed with almost no
harmonics
• Most common for wind farms
• Reactive Compensation / Sizing
Study Assess VAR support need to
meet regulatory requirements
• Load Flow / Voltage Drop
Confirm network load flow
conditions are with acceptable limits
across all operating conditions
• Harmonics
FACTS devices can be a significant
source of harmonics. This study is
necessary to determine if the wind
farm is operating within IEEE limits
and if mitigation is required
• Transient Stability
FACTs devices can provide voltage
support during transient events
such as system faults
• System Protection
Protection must be coordinated to
protect FACTS device while also
ensuring security through range of
operation
Software Packages
• ETAP, SKM, or PSS/E packages for
reactive compensation, load flow, and
protection studies
• EMTP, PSCAD, and PSS/E for
Harmonics and transient stability
Contact with equipment vendors vital to
obtain critical model input parameters
Takeaways
• FERC Rule 827 as well as recent ISO rule changes created stricter VAR support requirements for
new wind generation projects increasing the need for FACTS devices
• Two common types of FACTs devices available, SVCs and STATCOMs, with STATCOMs being the most
common
• FACTs devices require an array of analyses to support their deployment
• Recommend a detailed functional specification
• FACTS devices can be engineered to the specification and highly customizable
Smaller pre-engineered devices exist
(S&C Purewave, ABB PCS6000) and
these can be easier to work with. Tend
to come in blocks of VAR capability (up
to 15MVAR/35kV).
Bid Evaluation
• Important to include cost categories
within the specification to help
judge manufacturers.
• Bids received, especially for
transmission class devices, may be
specialized and highly customizable.
Manufacturers will spend a decent
amount of engineering time to
prepare a proposal.
• For a wind farm, depending on the
dynamic range and response time
needed, the best solution might
include a dynamic device
(containerized STATCOM) along with
an external cap bank
Loss evaluation is critical. This will force
manufacturers to make certain design
choices. Need to balance upfront cost
savings versus long term operating costs
S&L can provide support over the
lifecycle of the project
Piotr R. Wiczkowski is a Project Associate with Sargent &
Lundy’s Electrical Analytical Division. His experience in the wind
industry focuses on electrical analysis. These analyses include
reactive power compensation, voltage drop/regulation, short
circuit, transients, insulation coordination, and harmonics. Piotr
holds B.S. and M.S. degrees in electrical engineering from the
University of Illinois Urbana-Champaign. Piotr is a Licensed
professional engineer in the State of Illinois.