k14 main cmte presentation 20100114

8/3/2019 K14 Main Cmte Presentation 20100114

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IEEE C37.234 Guide for Protective

Relay Application to Power

System Buses

B.Kasztenny (Chairman), S.Conrad (Vice-Chairman),P.Beaumont, K.Behrendt, O.Bolado, J.Boyle, G.Brunello,

J.Burger, F.Calero, S.Chano, G.Dalke, A.Darlington, H.DoCarmo,

D.Fontana, Z.Gajic, J.Holbach, L.Kojovic, F.Lopez, D.Lukach,

D.McGinn, J.Miller, P.Mysore, J.O'Brien, B.Pickett,

S.Sambasivan, G.Sessler, V.Skendzic, J.Smith, D.Tholomier,

M.Thompson, J.Uchiyama, D.Ware, D.Weers, R.Whittaker,

R.Young, S.Zocholl

Presentation to the Main Committee of PSRC, January 14, 2010, Orlando, FL


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Table of Contents

Definitions

Bus configurations

Introduction to bus protection

Relay input sources

Bus protection methods

Application of bus protection schemes

Annexes


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Definitions

23new terms defined

Bus protection and primary equipment

breaker substitution Temporary usage of a bus tie breaker in a

multiple bus configuration to substitute for one of the networkelements circuit breakers, typically for the maintenance of the latter;

also known as breaker transfer

breaker substitution Temporary usage of a bus tie breaker in a

multiple bus configuration to substitute for one of the networkelements circuit breakers, typically for the maintenance of the latter;

also known as breaker transfer

check zone Nonselective part of a multi-zone bus protection

system measuring current flows around the entire station andsupervising selective tripping from individual bus zones of protection

check zone Nonselective part of a multi-zone bus protection

system measuring current flows around the entire station andsupervising selective tripping from individual bus zones of protection

stub bus Area of a bus or line that becomes isolated from theoriginal zone of protection or an area that loses protection due to the

loss of sensing to zone protection relays

stub bus Area of a bus or line that becomes isolated from theoriginal zone of protection or an area that loses protection due to the

loss of sensing to zone protection relays


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Bus design considerations

Continuity of service for the bus andessential network elements

Equipment maintainability and network

switching flexibility Economical and footprint constraints

Sectionalizing requirements to avoid

exceeding breaker fault duties

Ease of future bus expansion


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Bus arrangements

Single bus

Main and transfer bus

Double-bus double-breaker

Double-bus single-breaker

Breaker-and-a-half

Ring bus


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Introduction to bus protection

Zones of protection


Scheme selection guidelines


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Zones of protection


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Dynamic zones of protection


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Zones of protection

Over


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Differential Differentially-connected overcurrent

Instantaneous

Time-delayed

Percentage-restrained differential

Restrained

Advanced microprocessor based

High-impedance differential

Resistor-stabilized overcurrent

High-impedance

Partial differential overcurrent

Fault bus


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Zone-interlocked schemes

Simple blocking

Directional blocking

Time-coordinated relays overlapping the bus

Protection (sensors) built into the gas isolated

switchgear*

* Not covered in the Guide


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Scheme selection criteria

Bus arrangement and flexibility

Fixed vs. switchable buses

Availability and characteristics of CTs

For reconfigurable buses, availability ofauxiliary contacts of disconnect switches

Performance requirements

Security, Selectivity, Speed, Sensitivity

Cost and complexity


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Relay input sources

Current transformers Types

Accuracy classes

Equivalent circuit & time to saturation

No universal CT requirements

Voltage Transformers

Voltage trip supervision

Directional blocking schemes

Position of switches and breakers


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Detailed scheme review

Section 7 gives in-depth review of eachmethod following a consistent pattern

Theory of operation

Setting considerations

CT requirements

Application considerations


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Example High-impedance scheme

Voltage setting:

Above the maximum voltage for an

external fault assuming that one CT

saturates completely

High enough so that pickup current is

above the short circuit current on thesecondary of any PT or station service

transformer inside the bus zone

Below the accuracy class voltage

rating of the lowest accuracy class CT

in the differential circuit

Low enough so that pickup current is

below the minimum fault current for

the bus


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Example High-impedance scheme

CT requirements:

CTs dedicated to bus protection

(cannot be shared)

Equal CT ratios*

The accuracy class voltage rating ofthe CT with the lowest accuracy class

above the selected voltage setting,

with margin

* Ratio matching covered but discouraged


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Application of bus protection

Partial differential Loads

Capacitor banks

Application with overcurrent and distance relays

Combined bus and transformer zone

Buses with directly connected grounding

transformers

Application of auxiliary transformers

Generally discouraged


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Applications with paralleled CTs

Generally discouraged

Guidelines included


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Application of auxiliary tripping relays Lockout relays

Non-lockout relays

Ratings

Automatic reclosing after bus faults

Dynamic bus replica

Check-zone

Voltage trip supervision


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Dynamic bus replica


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Position of switches and breakers

Auxiliary contacts Scheme output89a 89b Declared position Discrepancy alarm

On Off Closed Normal

Off On Opened Normal

On On Closed Alarm

Off Off Closed Alarm

If not opened, then closed logic


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In-service transfer


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In-service transfer


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In-service transfer


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Check zoneCheck zone


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Application of CT trouble detection Detection methods

Fallback strategies

Reliable, selective tripping at thedifferential zone boundary

Line-side CT

Bus-side CT

Bus coupler considerations

The role of Breaker Failure protection


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Line-side CT

Bus


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CT column ground fault protection

In-zone grounds

Surge arresters

Safety grounds and circulating current whiletesting

In-zone grounding of out-of-service elements

In-service transfer of network elementsand breaker substitution


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Stub bus considerations

Breaker Failure considerations

Backup protection

Local backup

Duplicated relays

BF, batteries, wiring

Reverse-looking distance relays

Overcurrent relays

Remote backup


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Annexes

Setting example for a high-impedance

scheme (AnnexA)

Logic example for double-bus single-

breaker configuration (Annex B) Bus and Breaker Failure protection

Two zones, check zone and voltage supervision

In-service transfers and breaker substitution

Setting guidelines for differentially

connected OC schemes (Annex C)


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k14 main cmte presentation 20100114

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