A PRACTICAL GUIDE TOPERFORMING WIDE-AREACOORDINATION ANALYSIS
October 16, 2014
Authors and Presenters: Bipasha Barman, P.E. – POWER EngineersJason Clack, P.E. – POWER Engineers
3rd Author: Vernon Padaca, P.E. – POWER Engineers
Presentation Overview
Intro to Wide-Area Coordination Methodology Data Management Short-Circuit Model Evaluation Criteria Approach Selection Analysis Conclusions
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Introduction to Wide-Area Coordination
Definition:Wide-area coordination (WAC) analysis is the evaluation of protective device selectivity and sensitivity at a system level (multiple layers of adjacent terminals) with a goal of improving system reliability.
Background
Motivation for Paper Project Experience Limited Resources Available to Industry
Reasons to Perform a WAC Study Increase System Reliability Responsive Action to Unexplained
Outages Meet Regulatory Requirements
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WAC Analysis vs. Protection Evaluation
Challenges
Larger Scale Study
Collecting and Managing Data
More Upfront Planning Required to Be
Efficient
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Methodology (Part 1)
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Methodology (Part 2)
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Planning Stage
Define Scope of Analysis
System Boundaries
Operating Conditions
Protective Devices and Elements
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Data Management
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More Data Required for WAC Analysis
Establish File/Folder Structure
Consider Using Revision Control Software Use for Living
Documents
Short-Circuit Model
Determine If System Model Exists Yes -> Is model complete and up-to-
date? Gain Familiarity with Software Package Automation Tools? Additional Data Required?
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Short-Circuit Model
Typical Data Needed Protective Device Settings CT and VT Ratios Single-Line & Three-Line Drawings System Boundary Source Equivalents Ratings & Impedances for Apparatus
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Evaluation Criteria Document
Serves as Starting Point for Evaluation Not Intended to Standardize Protection Sections to Include: Description of Study Boundaries Operating Configurations Contingencies Selected Approach Evaluation Criteria by Protection Type Critical Notes and Assumptions
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Evaluation Criteria Document
Define General Trip Times to Use as Rule of Thumb:
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Evaluation Criteria Document
Define Criteria in Terms of Ranges:Z1PMIN = 60% ZLINE
Z1PMAX = 80% ZLINE
Z1PPREF = 70% ZLINE
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Presentation Overview
Intro to Wide-Area Coordination Methodology Data Management Short-Circuit Model Evaluation Criteria Approach Selection Analysis Conclusions
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Considerations for Approach Selection
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Factors Driving Approach Selection: System Topology Schedule Constraint
Variables: Operating Scenarios Protection Schemes Protective Elements
Approach Selection
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Subset Boundaries
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Establish Criteria for Subset Boundaries
Example
Operating Scenarios
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Develop Strategy with Focus on Selectivity
Goal is to Define Maximum, Normal and Minimum Fault Levels
Factors: Weak or Strong Source Seasonal Generation N-1 Contingencies
Protective Element Evaluation Sequence
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Develop Strategy with Focus on Selectivity
Determine Sequence of Evaluating
Protective Elements
Primary Then Backup Elements
Underreaching Then Overreaching
Coordination Analysis: Flowchart (Pt. 1)
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• Focus on Selectivity
Coordination Analysis: Flowchart (Pt. 2)
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• Focus on Selectivity
Ways to Gain Efficiency
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Automate Calculation Tools
Streamline Short-Circuit Analysis
Utilize Coordination Checking Tool
Develop Calculation Spreadsheet Input Data
Automated Tool
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Develop Calculation Spreadsheet
Line Data Sequence Impedance Maximum Torque Angle
Automated Tool
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Calculate Results Fault Analysis
Input Programmed
Cells
Automated Tool
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= Z1Line • 1.2
= Apparent Z • 0.9
Utilize to Calculate Final Setting Evaluate: Existing Preferred Recommended
Automated Tool
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Streamlining Short-Circuit Analysis
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Defining Points of Fault Placement Line Apparatus
Fault Type Balanced Faults Unbalanced Faults
Automated Coordination Checking Tool
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Overcurrent/Distance Coordination Select Primary Relay Program its Backup Relay Group Select Type of Faults and their Placement Enter Desired CTI
Check Coordination Against the Relays Serving as Backup Against the Relays that it Backs up
Automated Coordination Tool
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Reports Miscoordination Flags the Elements Margin of Violation Fault Type
Improve Coordination Adjust Time Dial, Pickup and Curve Adjust Reaches, Timers Re-evaluate Coordination
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Example - Looped System
Time-Delayed Directional Overcurrent Ground Elements
Coordination Challenge
Solution to Coordination Challenge
Overcurrent Coordination Checking Tool Helped: Decide Close-in SLG Fault Placement Strategize Mitigation Set Pickups at 30% of the Smallest
Ground Fault at the Remote Bus Choose Time Dials to Trip after 39
cycles
Conclusions
WAC Analysis is Not Trivial. The Following Helps to Improve Project Outcome: Careful Upfront Planning Documenting Evaluation Criteria Keeping Files Organized Establishing a Systematic Approach Using Automated Tools
Questions
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References
[1] North American Electric Reliability Council, CIP-014-1 — Physical Security, 2014.
[2] North American Electric Reliability Council, PRC-023-2 -Transmission Relay Loadability, 2012.
[3] IEEE C37.113-1999 - IEEE Guide for Protective Relay Applications to Transmission Lines, New York: Institute of Electrical and Electronics Engineers, Inc., 1999.
[4] IEEE 242-2001 - IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems, New York: Institute of Electrical and Electronics Engineers, Inc., 2001.
