Line Outage Identification Based on AC Power Flow and Synchronized - - PowerPoint PPT Presentation

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Line Outage Identification Based on AC Power Flow and Synchronized Measurements

Zhen Dai, Joseph Euzebe Tate Department of Electrical and Computer Engineering University of Toronto zhen.dai@mail.utoronto.ca

Paper No: 20PESGM0226 Discovery Grant NSERC RGPIN-2016-06674

Background

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• Problems: inaccurate dc model, unrealistic assumptions, and misidentification
• Proposed method: Identification + Rejection Filter
• 0.03
• 0.025
• 0.02
• 0.015
• 0.01
• 0.005

real delta phasor

• 0.057
• 0.056
• 0.055
• 0.054
• 0.053
• 0.052
• 0.051
• 0.05

imag delta phasor

correct

misidentified

filter threshold

correct filtered misidentified filtered

• Fig. 1

Stage 1: Identification

Compare expected voltage changes (via ac power flow) to observations

Stage 2: Rejection filter

Examine the distance between the best candidate to the second best Tested on various systems using random PMU placements and noisy measurements

5 10 15 20 25 30 20 40 60 80 100

nPMUs

percentage

Correct Misidentified MisidentifiedFiltered CorrectFiltered

Results

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nPMUs percentage ac correct dc correct

20 40 60 80 100 5 10 15 20 25 30

Comparison of the dc and ac approaches

• Fig. 3

Stage 1: Identification Stage 2: Filtering The 30-bus system

• AC > DC

Misidentified Filtered Misidentified Correct Filtered Correct

• Rejection filter
• More PMUs

Results

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Identification results versus the filter threshold

• Fig. 5 (a) 26 PMUs

The Ontario system (3488 buses) (c) 868 PMUs (220 kV+)

• Threshold

Misidentified Correct

• More PMUs

Correct Correct Filtered

Conclusions/Recommendations

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• Ac model necessary for higher accuracy
• Rejection filter to overcome misidentification due to

measurement uncertainties

• Significant benefits of having a higher PMU coverage