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

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Challenging…..

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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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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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WAC Analysis vs. Protection Evaluation

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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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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Bipasha Barman, P.E. – POWER Engineers

bipasha.barman@powereng.com

(208) 288 6306

Challenges

Larger Scale Study

Collecting and Managing Data

More Upfront Planning Required to Be

Efficient

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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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