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TRANSCRIPT
A PRACTICAL GUIDE TO
PERFORMING WIDE-AREA
COORDINATION ANALYSIS
November 10, 2015
Author and Presenter:
Bipasha Barman, P.E. – POWER Engineers
Other Authors:
Jason Clack, P.E. – POWER Engineers
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
4
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
Reasons to Perform a WAC Study
Increase System Reliability
Responsive Action to Unexplained
Outages
Meet Regulatory Requirements
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Planning Stage
Define Scope of Analysis
System Boundaries
Operating Conditions
Protective Devices and Elements
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Data Management
11
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?
12
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
13
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
14
Evaluation Criteria Document
Define Criteria in Terms of Ranges:
Z1PMIN = 60% ZLINE
Z1PMAX = 80% ZLINE
Z1PPREF = 70% ZLINE
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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
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
21
Develop Strategy with Focus on Selectivity
Determine Sequence of Evaluating
Protective Elements
Primary Then Backup Elements
Underreaching Then Overreaching
Ways to Gain Efficiency
24
Automate Calculation Tools
Streamline Short-Circuit Analysis
Utilize Coordination Checking Tool
Calculate Results
Fault Analysis
Input
Programmed
Cells
Automated Tool
27
= Z1Line • 1.2
= Apparent Z •
0.9
Streamlining Short-Circuit Analysis
29
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
35
Bipasha Barman, P.E. – POWER Engineers
(208) 288 6306
Challenges
Larger Scale Study
Collecting and Managing Data
More Upfront Planning Required to Be
Efficient
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