1

Overview

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Overview

• Benefits of RATC• Applications

― Real-time corrective ― Hour ahead corrective and preventive― Day ahead corrective― Day ahead market/economic based

• RATC algorithms

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Benefits of RATC

• Market models (day-ahead, hour-ahead) do not guarantee N-1 feasibility

• RATC reduces contingency violations• RATC reduces costly out of market corrections

Market Model

Contingency Analysis

Out of Market Corrections

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Benefits of RATC with Renewables

• Renewable resources― Renewables impose locational reserve

requirements― RATC improves reserve deliverability, reduces

need for investment in local generation― RATC minimizes costly re-dispatch caused by

renewables― Enables higher percentage levels of

renewables

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Expected RATC Benefits

• Cost savings: >2-5% avoided costs

• System reliability― N-1, N-m, malicious attacks can be mitigated

using real-time RATC

― Reduction in load shedding: >5-10%

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Real-Time Corrective

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Real-time Structure

• Computational time: < 5 min.

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Real-time Corrective Algorithm

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Real-time Corrective Topology Control Examples

• PJM (2010) Manual 3: Transmission Operations. http://www.pjm.com/markets-and-operations/compliance/nerc-standards/~/media/documents/manuals/m03.ashx

• Sunnyside-Torrey 138 kV Operating Guide (AEP Operating Memo T029) – Historically, the Sunnyside-Torrey 138 kV overloads on

the outage of the South Canton – Torrey 138 kV line. Opening the S.E. Canton 138 kV CB at Sunnyside will help to reduce the post-contingency flow on the Sunnyside-Torrey 138 kV line.

– Page 107

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Superstorm Sandy• PJM lost 82 bulk electric facilities

– 6 500kV transmission assets ; 3 345kV transmission assets ; 39 230kV transmission assets ; 25 138kV transmission assets

• Caused extremely high voltage on the system during low load levels

• “We were dealing with extremely high voltage on the system but a switching plan was developed to help alleviate these conditions.”

• Via Andy Ott, VP of PJM: several 500kV lines were switched out to mitigate over voltage concerns during these low load level periods

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Hour Ahead Corrective

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Hour Ahead Corrective Structure

• Computational time: < 15 min.

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Hour Ahead Corrective Algorithm (Renewables)

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Hour Ahead Corrective Results

IEEE 118-bus Test CaseWind uncertainty: ±16%Reserve: 5% non-wind + 10% wind or largest contingency

Results to date from IEEE 118:• RATC produces multiple candidate switching actions for

single events/contingencies• Candidate switching actions solve multiple events• Market solution (without RATC) failed N-1 contingency

analysis with forecasted wind level• Market solution with RATC is N-1 reliable and robust

against renewable uncertainty

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Hour Ahead Preventive

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Hour Ahead Preventive Structure

• Computational time: < 15 min.

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Hour Ahead Preventive Algorithm (Renewables)

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Day Ahead Corrective

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Day Ahead Corrective Structure

• Computational time: 2-3 hrs.

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Day Ahead Corrective Algorithm

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Hour Ahead Corrective Results

IEEE 118-bus Test CaseDemand uncertainty: ±6%Reserve: 5% hydro + 7% non-hydro or largest contingency

Results to date from IEEE 118:• RATC produces multiple candidate switching actions for

single events/contingencies• Candidate switching actions solve multiple events• Market solution (without RATC) failed N-1 contingency

analysis with forecasted demand• Market solution with RATC is N-1 reliable and robust

against demand uncertainty

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Day Ahead Market/Economic

Based

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Day Ahead Market Based Structure

• Computational time: 2-3 hrs.

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Day Ahead Market Based Algorithm

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Day Ahead Market Based RATC Results

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RATC Algorithms

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Topology Control Algorithms

• Greedy algorithm• Based on a sensitivity analysis• Fast, scalable algorithm for large-scale systems• Medium to short-term RATC applications

• MIP heuristic• Finds the best single switching action• Long to medium-term RATC applications

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Greedy Algorithm

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MIP Heuristic

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Test Systems

• IEEE Test Systems• PJM Dataset via FERC• TVA