NPCC Task 5 Study NPCC Task 5 Study New York State Reliability - - PowerPoint PPT Presentation

NPCC Task 5 Study NPCC Task 5 Study

New York State Reliability Council Executive Committee Meeting

Quoc Le – NPCC Manager of System Planning and Protection

1 Northeast Power Coordinating Council Inc. February 10, 2012

Presentation Outline Presentation Outline

• Background

Background

• Study Objectives

h d l

• Methodology
• Summary of Results
• Conclusions
• Recommendations

Recommendations

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Background Background

• The Blackout Study included six separate tasks

The Blackout Study included six separate tasks

• Final report (Task 6) issued following the completion
• f Tasks 1‐4

– Report approved Nov. 2005

• Task 5 is the remaining Blackout Study task to be

Task 5 is the remaining Blackout Study task to be completed

• Task 5 delayed due to prioritization of work (e.g.

y p ( g UFLS, OTA, etc.)

February 10, 2012 NPCC ‐ Quoc Le 3

Objectives Objectives

• Investigate potential mitigation measures to

Investigate potential mitigation measures to improve ability of system to withstand a major system disturbance system disturbance

• Review NERC technical reference on Power

Plant and Transmission System Protection Plant and Transmission System Protection Coordination and recommend protection functions that could benefit from including functions that could benefit from including explicit or screening models in studies

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Methodology Methodology

• Develop study cases

Develop study cases

• Assess coherent generation groups
• Investigate potential advance indicators of
• Investigate potential advance indicators of

system separation

• Assess performance of post contingency
• Assess performance of post contingency

actions

• Assess benefits of tripping where out‐of‐step
• Assess benefits of tripping where out‐of‐step

conditions occur

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Results of Coherent Generation l Groups Analysis

• Two coherent generation groups (N‐S‐C‐E and

Two coherent generation groups (N S C E and NE‐S‐C‐E) identified for Ontario

• One coherent generation group identified for
• One coherent generation group identified for

the Maritimes consistent with prior study T h i (N

• Two coherent generation groups (New

England‐Maritimes and Northern Maine‐ M i i ) id ifi d f N E l d Maritimes) identified for New England

• One coherent generation group identified as

West of Central East for New York

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Evaluation of Potential Advance d f Indicators of System Separation

• Change in power flow supervised by change in bus

g p p y g voltage angle

• Triggers using Phasor Measurement Unit data

– Bus voltage angle difference – Bus frequency difference and its derivative – Bus voltage magnitude and its derivative Bus voltage magnitude and its derivative

• Bus voltage angular velocity vs. bus voltage angular

acceleration

• Generator rotor speed/frequency and acceleration
• Reactive power and its derivative (Q‐Qdot)

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Performance of post contingency actions

• Bus frequency responses demonstrated

Bus frequency responses demonstrated controlled system separation/islanding along boundaries that minimize generation load boundaries that minimize generation load mismatch is preferable to uncontrolled separation separation

• Out‐of‐step generation rejection

demonstrated potential for preventing demonstrated potential for preventing uncontrolled system separation

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Results on Tripping where OOS d conditions occur

• The system would still have separated as it did

The system would still have separated as it did

• n August 14, 2003 even if the two 120 kV

cables connecting Southern and Northern cables connecting Southern and Northern Detroit were tripped

• System separation at locations where out of
• System separation at locations where out‐of‐

step conditions occur helps reduce voltage and power oscillations and power oscillations

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Conclusions Conclusions

• It is beneficial to separate the system where out‐

It is beneficial to separate the system where out

• f‐step conditions occur
• Controlled system separation is preferred in the

Controlled system separation is preferred in the presence of a single coherent generation group

• A reliable advance indicator for system separation
• A reliable advance indicator for system separation

could not be determined from this study

• Uncoordinated generation protection schemes
• Uncoordinated generation protection schemes

should be modeled in planning and system studies studies

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Recommendations Recommendations

• Further studies are needed to determine the

Further studies are needed to determine the reliability of the advance indicators for system separation p

‐ Need to be specific to particular locations, regional boundaries, or interfaces

• Types of study identified which would benefit from

including explicit or screening models for generator f protection functions

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Generator Protection Functions to be Study Type Modelled via explicit Models via Screening Models UFLS Assessment Over/under-frequency V/Hz (24), under- (81), OOS (78) voltage (27), over- voltage (59) UVLS Study Under-voltage (27), lt (59)

• ver-current (51V)
• ver-voltage (59)

Analysis of Large System Disturbance (eg Event Over/under-frequency (81), under-voltage (27) over-voltage (59) V/Hz (24), over-current (51V) (eg. Event reconstruction of large scale blackout/system breakup) (27), over-voltage (59), OOS (78) b ea up) Overall Transmission Assessments Over -frequency (81), OOS (78) under-voltage (27),

• ver-voltage (59)

Inter-regional Over-frequency (81), under-voltage (27),

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Transmission Studies OOS (78)

• ver-voltage (59)