Overview of SPS in ERCOT
•February 5, 2004
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Existing SPS
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Current In-Service Special Protection Systems (SPS) on grid
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Trip Hays generation to protect Kendall 345/138 kV Auto
Trip GPP & Rio Nogales generation to protect Marion to GPI 138 kV circuit
Trip DC Tie to protect for transient stability for close-in 345 kV faults
Trip DC Tie to protect Monticello-Sulphur Springs-Allen 345 kV circuits*
Trip LPP generation to protect Paris-Valley 345 kV & 138 kV circuits
Trip KPP & Valley generation to protect Valley-Anna & Valley Farmersville 345
kV circuits*
Trip Gateway generation to protect for transient instability
Trip Ennis generation to protect Ennis-Ennis West & Ennis West-Sterrett 138
kV circuits
Trip Parker-Roanoke 345 kV circuit to protect Roanake 345/138 kV auto
Trip Trent Wind Farm to protect Eskota Sw-South Abilene 138 kV circuit
Trip MELP generation to protect various circuits out of Venus & Everman
includes remote monitoring of circuits and autos
* To be modified in the Oncor proposal
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Oncor NE CM Proposal
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Modifies existing SPS with additional remote monitoring to automatically
trip Valley & KPP in stages to protect several circuits
Modifies existing SPS with additional remote monitoring to automatically
trip DC Tie to protect several circuits
Add SPS to automatically trip Valley #2 138 kV generation to protect both
Valley-Payne 138 kV circuits
Add SPS to automatically trip breaker on Valley-Payne #2 138 kV circuit
to protect Valley 345/138 kV autotransformer to minimize 345 kV
generation tripping
Add SPS to automatically trip breaker on Collin-Bridges 138 kV circuit to
protect this line
Add SPS to automatically trip breaker on E. Mesquite-W. Mesquite 138 kV
circuit to protect this line
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ERCOT SPS Requirements
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Coordinated and approved with all affected parties
Use is limited to the time required to construct replacement transmission
facilities, or replacement transmission facilities have been determined by
ERCOT to be unnecessary (e.g., due to unacceptably high cost, inability
to construct, or agreement by all affected parties).
Complies with all applicable ERCOT & NERC requirements
SPS must be fully automatic
SPS must not unnecessarily operate
The possible interaction of multiple SPS installations is considered
A methodology and medium for ERCOT Security Operations monitoring
of the conditions that would actuate the SPS is provided.
It must be reviewed again whenever it is modified, after it has been in
service more than five years, or whenever ERCOT believes system
conditions merit its re-evaluation.
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Additional Requirements Included
in the NE SPS
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Develop and install a “smart” monitoring and real time system
including automatic oversight and data collection
Develop a comprehensive list of elements that could impact
the SPS operation during outages/maintenance
Inspection of all critical facilities in May and November of each
year for all SPS
Incorporate all SPS into TO and ERCOT System Operations,
clearances coordination and TCR calculations
Misoperation will result in removal of SPS
Develop exit strategy
Perform probabilistic, steady state and dynamic studies of
impacts of all SPS
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NERC Planning Standards on SPS
S1. An SPS shall be designed so that cascading transmission outages or
system instability do not occur for failure of a single component of
an SPS which would result in failure of the SPS to operate when
required.
S2. Misoperation, incorrect operation, or unintended operation of an SPS
when considered by itself and not in combination with any other
system contingency shall meet the system performance
requirements as defined under Categories A, B, and C of Table I of
the I.A. Standards on Transmission Systems.
S3. All SPS installations shall be coordinated with other system protection
and control schemes.
S4. All SPS operations shall be analyzed for correctness and documented.
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NERC Guides on SPS
Guidelines define “Good Utility Practice”
G1. Complete redundancy should be considered in the design of an SPS
with diagnostic and self-check features to detect and alarm when
essential components fail or critical functions are not operational.
G2. No identifiable common mode events should result in the coincident
failure of two or more SPS components.
G3. An SPS should be designed to operate only for conditions that require
specific protective or control actions.
G4. As system conditions change, an SPS should be disarmed to the extent
that its use is unnecessary.
G5. SPSs should be designed to minimize the likelihood of personnel error,
such as incorrect operation and inadvertent disabling. Test devices or
switches should be used to eliminate the necessity for removing or
disconnecting wires during testing.
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Compliance
ERCOT Measurements
M1. Each Region whose members use or are planning to use SPSs shall have a
documented Regional review process for SPSs to ensure that they comply
with Regional criteria and guides and the NERC Planning Standards.
M2. Each Region shall periodically review and document existing SPSs for
compliance with the Regional planning criteria and guides and the NERC
Planning Standards.
TDSP Measurements
M3. New or modified SPSs shall be reviewed for design and functional operation
prior to being placed in service. The results of the compliance review shall be
documented and provided to appropriate Regions and NERC upon request.
(S1, S2)
M4. The design and functional operation of an SPS shall be coordinated and
reviewed with affected systems according to Regional compliance review
processes. (S3)
M5. Each Region shall have a process for the monitoring, notification, and
analysis of all SPS operations. Documentation of SPS failures or misoperations
shall be provided to the appropriate Regions and NERC on request. (S4)
M6. Each SPS owner shall have an SPS maintenance and testing program.
Documentation of the implementation of SPS maintenance and testing shall
be provided to the appropriate Regions and NERC on request. (S1, S2)
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