Power System Stabilizer Guideline - SERC

SERC Guideline
Power System Stabilizer

SERC Power System Stabilizer Guideline
Revision History
Revision Date Comments
0 05/25/05 Initial approval of document.
1 08/08/08 Incorporated some minor updates and to
establish it as a separate document from
the FCR Supplement
2 10/06/11 Made minor editorial revisions
Responsible SERC Sub-group & Region Review Group
The SERC EC Dynamic Review Subcommittee (DRS) is the Responsible SERC Sub-group
(RSS) for this guideline.
Review and Recertification Requirements
This guideline will be reviewed every three years or as appropriate by the DRS for possible
revision. The existing or revised document will be re-certified and distributed to all members by
the SERC Engineering Committee.
SERC EC Approved on October 6, 2011 Rev 2
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SERC Power System Stabilizer Guideline
SERC Power System Stabilizer Guideline
Power oscillations on the transmission grid are becoming a problem for the transmission
system in the SERC Region. A Power System Stabilizer (PSS) is an electronic feedback control
that is a part of the excitation system for generating units. The PSS acts to modulate the
generator field voltage to dampen power system oscillations. FERC Order 2003 states that
“The Interconnection Customer shall procure, install, maintain and operate Power System
Stabilizers in accordance with the guidelines and procedures established by the Applicable
Reliability Council. Transmission Provider reserves the right to reasonably establish minimum
acceptable settings for any installed Power System Stabilizers, subject to the design and
operating limitations of the Large Generating Facility. If the Large Generating Facility’s Power
System Stabilizers are removed from service or not capable of automatic operation, the
Interconnection Customer shall immediately notify the Transmission Provider’s system provider,
or its designated representative.”
Historically, transmission systems have needed stabilizers at only a few special locations.
However, as transmission systems become increasingly loaded and generators are added, the
stability margins of the transmission system become more critical. Stability studies have shown
that while the first new generator added in an area may not cause a power oscillation problem,
the subsequent addition of generation in the area may result in oscillatory conditions requiring
the new and/or existing generation in the area to have stabilizers.
It is easier and less expensive to activate a PSS at the time the generator is put into service
than to add it at a later date. In order to insure the integrity and reliability of the transmission
system, SERC recommends that a PSS be procured, installed, tuned, and activated on all new
resources interconnecting with the transmission system.
If generators that were in service before the effective date of this guideline receives excitation
system or voltage regulator replacements, then a stabilizer is recommended to be procured and
installed. If the Transmission Planner determines the need, or if the generator already had an
in-service stabilizer before the excitation system or voltage regulator replacement, these
retrofitted stabilizers should be tuned and activated. Following the effective date of this
guideline, if the need for a stabilizer is identified by the Transmission Planner for an existing
unit, the Transmission Planner may require the Generator Owner to procure, install, tune and
activate a stabilizer.
The Generation Owner is responsible for the procurement, tuning and testing of the exciter and
stabilizer controls for optimum performance and for providing a stabilizer model and data
consistent with the requirements of the individual Transmission Planner.
The stabilizer is expected to be an accelerating power delta-P-omega (ΔPω) type. Other types
that are functionally equivalent to the delta-P-omega type may be accepted on a case-by-case
basis. Special studies and field tests are required to tune a PSS and to establish its settings.
These studies and field tests will be the responsibility of the Generator Owner prior to
commercial operation. It is anticipated that most of the time, the generator equipment vendor
can be retained to perform the studies and tests. The Transmission Planner should perform
other relevant studies and should coordinate with the Generation Owner and the equipment
vendor (or consultant) to establish reliable settings for the PSS. SERC recommends that for
new generators the PSS tuning test documentation as specified in the SERC Regional Criteria
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SERC Power System Stabilizer Guideline
System Modeling Data Requirements be provided prior to commercial operation. For the retrofit
of a PSS to an existing unit, the documentation should be provided when the testing of the PSS
is complete. If future system conditions change significantly, the Transmission Planner may
request the Generator Owner to reset the PSS parameters to more appropriate settings to
preserve the overall reliability of the grid.
The Transmission Planner may provide criteria to allow the power system stabilizer to be taken
out of service. The PSS should be taken out of service for scheduled maintenance only
following consultation between the Generator Owner and the Transmission Operator and with
the agreement of the Transmission Operator. The Generator Owner should be requested to
take the PSS out of service if the Transmission Operator identifies transmission system
operating conditions during which the operation of the PSS adversely affects the stability of the
transmission system or its connected generators. If a power system stabilizer is removed from
service or is not capable of automatic operation, the Generator Owner should immediately notify
the Transmission Operator. Operating limits may apply in such cases based on system needs
identified by the Transmission Operator.
Unless the Transmission Planner determines that system studies or operating experience
show need for a PSS, then generators rated less than or equal to 50 MVA or generators
connected at a nominal system voltage level below 100 kV are not expected to install a new
PSS. This only applies to plants where the total generation does not exceed 300 MVA.
The guideline is effective upon approval by the SERC Engineering Committee.
SERC EC Approved on October 6, 2011 Rev 2
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