Pankaj Khali, ABB India Limited Representing :ABB ... · PDF fileGenerator Circuit-Breakers Technical Seminar: PLN Pankaj Khali, ABB India Limited Representing :ABB Switzerland limited,

Generator Circuit-BreakersTechnical Seminar: PLN

Pankaj Khali, ABB India Limited Representing :ABB Switzerland limited, September 2016

Agenda

§ Advantages of Generator Circuit-Breakers

§ Criteria of Selection and Technical Requirements

§ ABB Portfolio Overview and Critical Design Aspects

§ New Standard: IEC/IEEE 62271-37-013

© ABB GroupSeptember 17, 2016 | Slide 2


Advantages of GeneratorCircuit-Breakers


Connection with Generator Circuit-BreakerUnit connection (without GeneratorCircuit-Breaker)

Introduction

G

EHV HV

MT

UT ST

AUX G

EHV HV

MT

UT STGenCB

AUX


with Generator Circuit-Breaker

Introduction

G

EHV

MT

UTGenCB

AUX G

EHV

MT

UTGenCB

AUX


without Generator Circuit-Breaker with Generator Circuit-Breaker

G

EHV

MT

UTSS

GenCB

SFCG

EHV HV

MT

STSS

SFC

AUX

Typical Layouts for Gas Turbine Power Plants

Introduction


Advantages of Generator Circuit-BreakersSimplified Operational Procedures

§ During the starting-up or shutting-down of thegenerator only one circuit-breaker has to beoperated thus reducing the number of switchingoperations necessary

§ The responsibilities for the operation of the powerplant and the high-voltage grid are clearly defined

Simplifiedoperation

procedures

Improvedprotection

Higherpower plantavailability

Economicbenefits


§ Maximum selectivity of protection zones

§ Rapid and selective clearance of all types offaults

Bursting of the transformer tank following an internal fault inthe main or unit transformer

Advantages of Generator Circuit-BreakersImproved Protection

Simplifiedoperation

procedures

Improvedprotection


Economicbenefits


Fault Current

Time

Advantages of Generator Circuit-BreakersInterruption of Generator-Fed Fault Currents

Interruption of Generator-Fed Fault Currents – Case without GeneratorCircuit-Breaker (Unit Connection)

IsIgGridG

Is+Ig

Ig

Interruption of HVCircuit-Breaker

tens of ms seconds


Fault Current

Time

Advantages of Generator Circuit-BreakersInterruption of Generator-Fed Fault Currents

Interruption of Generator-Fed Fault Currents – Case with GeneratorCircuit-Breaker

IsIgGridG

Is+Ig

Ig

tens of ms seconds

Interruption of HVCircuit-Breaker

Interruption of GeneratorCircuit-Breaker


t [ms]

2.5

2.0

1.5

1.0

0.5

Gen

erat

orC

ircui

t-Bre

aker

HV

Circ

uit-B

reak

er

P [bar]

tank withstand pressure

50 100 150 250200

fault to tank from HV winding

full winding shorted HV side

shorted winding (portion)

tap changer contact fault 15%

Tap Changer

25%30%fault across bushing

10%5%

Pressure Rise in Power Transformers


Equipment FailuresMain Transformer Failures

Generator Transformer Failure - withoutGenerator Circuit-Breaker

Sequence of events:

t = 0 ms: earth fault atHV-side of transformer

t = 45 ms: 2-phaseshort-circuit

t = 95 ms: 3-phaseshort-circuit

t ≈ 150 ms: explosion oftransformer





Thermal destruction of the generator damper winding dueto short-time unbalanced load conditions


Simplifiedoperation

procedures

Improvedprotection


Economicbenefits


Advantages of Generator Circuit-BreakersShort-Time Unbalanced Load Conditions

Single and twophase faults

Inversecomponent

interacts withdamper windings

Criticalmechanical andthermal stresses


Equipment FailuresShort-Time Unbalanced Load Conditions

Unbalanced Load Condition – withoutGenerator Circuit-Breaker






Mechanical destruction of a turbine-generator set due togenerator motoring


Simplifiedoperation

procedures

Improvedprotection


Economicbenefits


Equipment FailuresGenerator Motoring - without Generator Circuit-Breaker

GS3~

GeneratorPn = 500 MW

Main Transformer Overhead Line(Transmission)

Coupling

Overhead Line

HV Circuit-Breaker

Internal breakdown at HV circuit-breaker, pole L1•Generator starts working as motor

•Speed is increasing again

Open command•Three-phase network interruption

•Turbine-generator unit is running down normally

Mechanical destruction of turbine-generator set•Shaft and bearings are destroyed

•Generator is lifted out of the foundation

•12 meter high explosive flame


n [min-1] Object

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

3000

02 4 6 8 10 12 14 160 18 20 22 24 26 28 30 32

n [min -1]

t [min]

2420 Generator

870 Generator

2040

1800

20101940 Turbine

Critical Rotor Speed

normal run down

1643

2142

after mechanicaldestruction

Equipment FailuresGenerator Motoring - without Generator Circuit-Breaker






Mechanical destruction of a turbine-generator set due togenerator motoring

Thermal/dynamic stress caused to the generator bysynchronising under “out-of-phase” conditions


Simplifiedoperation

procedures

Improvedprotection


Economicbenefits


Advantages of Generator Circuit-BreakersHigher Power Plant Availability

Simplifiedoperation

procedures

Improvedprotection


Economicbenefits

IncreasedAvailability

The rapid andselective

clearance of alltypes of faults

More reliablesynchronisation

Unit auxiliariessupplies drawn

directly frommain grid

The avoidanceof changeover

switchingoperations

Simplifiedoperationalprocedures


Advantages of Generator Circuit-BreakersEconomic Benefits

Simplifiedoperation

procedures

Improvedprotection


Economicbenefits

§ Integration of all the associated items ofswitchgear into the generator circuit-breakerenclosure

§ Possible to omit the station transformer and theassociated high-voltage and medium-voltageswitchgear

§ The through-fault capability required of the unittransformers is substantially reduced

§ Higher availability in turn leads to an increasednumber of the operating hours and therefore to ahigher profit for the operator of the power plant


Availability CalculationLayout of Power Station

2 x 600 MW Power StationLayout with GeneratorCircuit -Breaker

2 x 600 MW Power StationLayout with GeneratorCircuit -Breaker andShut-Down Transformer

2 x 600 MW Power StationUnit Connection

Reference ScenarioCase 1Case 2Case 3


Availability CalculationResults of Availability Calculation

Results of AvailabilityCalculation for one 600 MWUnit - Average PowerThroughput

Pow

er[M

W]

520

515

510

505

500

525

530

Cas

e2

Cas

e1

Cas

e3

Average Power Output of Unit (Assumed Value)


Criteria of Selection andTechnical Requirements


Criteria of Selection and Technical RequirementsDuties of Generator Circuit-Breakers

§ Synchronise the generator with the main system

§ Separate the generator from the main system (switching off theunloaded/lightly loaded generator)

§ Carry and interrupt load currents (up to the full load current of thegenerator)

§ Interrupt system-source short-circuit currents

§ Interrupt generator-source short-circuit currents

§ Interrupt fault currents due to out-of-phase conditions up to out-of-phase angles of 180°


Short-Circuit Current Interruption

t [ms]50403020100-10-20-30-40

u (t)

i (t)

Characteristics of short-circuitcurrent

Characteristics of transientrecovery voltage (TRV)

separation of arcing contact

Criteria of Selection and Technical RequirementsRequirements for Generator Circuit-Breakers


t[ms]

50403020100-10-20

-30

-40

u (t)

i (t)



§Rate-of-rise

High technical requirements are imposed on the circuit-breaker with respect to:

§ Rated current

§ Short-circuit currents (system-source and generator-source)

§ Fault currents due to out-of-phase conditions

§ Degree of asymmetry of fault currents, fault currentswith delayed current zeros

§ Rate-of-rise of the recovery voltages

§Magnitude§Asymmetry

Criteria of Selection and Technical RequirementsStandards for Generator Circuit-Breakers


§IEEE Std C37.013 / IEEE Std C37.013a

§IEC 62271-100

Circuit-breakers that have beendesigned and tested in

accordance with IEC 62271-100do not meet the stringentrequirements imposed on

generator circuit-breakers andtherefore are not suitable for the

use as generator circuit-breakers.


§ Rated maximum voltage

§ Rated power frequency

§ Rated insulation level (dielectric strength): Lightning impulsewithstand voltage and power frequency withstand voltage

§ Rated peak and short-time withstand current

§ Rated current

§ Closing and making time

§ Opening and breaking (interrupting) time

§ Duty cycle (operating sequence)

§ Rated short-circuit making current (closing and latching capability)

Criteria of Selection and Technical RequirementsSelection of Generator Circuit-Breaker


§ Rated short-circuit breaking current(system-source short-circuit breaking current):Symmetrical value, degree of asymmetry, TRV capabilities

§ Generator-source short switching capability:Symmetrical value, degree of asymmetry, TRV capabilities

§ Out of phase current switching capability:Symmetrical value, degree of asymmetry, TRV capabilities

§ Load current switching capability:Symmetrical value, TRV capabilities

Selection of Generator Circuit-Breaker


System-Source Short-Circuit Current

110 kVSk = 10 GVA

100 MVA110/13.8 kV

uk = 12 %

99 MVA13.8 kV

cos j = 0.8X’’dv = 13.5%

Contact parting time 50ms:

Ipk = 90.5 kA Isym = 33.2 kA a = 63.5 %

IscTS

G


System-Source Short-Circuit Current

Characteristics of asymmetry:

=

AC /symmetrical

current

DCcurrent

Asymmetricalcurrent

+

ac

dc

IIa2

=

dcI

acI2

System-Source Short-Circuit CurrentSurvey - Terminal Fault Prospective Currents (tcs = 40 ms)


0

50

100

150

200

250

0 500 1000 1500 2000

I SCsy

s(k

Arm

s)

Generator Rated Power (MVA)

System-Source Short-Circuit CurrentSurvey - Terminal Fault Prospective Currents (tcs = 40 ms)


0

20

40

60

80

100

0 500 1000 1500 2000

DOA s

ys(%

)

Generator Rated Power (MVA)

Average DOAsys = 72.2%No DOAsys > 100%


Generator-Source Short-Circuit Current

110 kVSk = 10 GVA

100 MVA110/13.8 kV

uk = 12 %

99 MVA13.8 kV

cos j = 0.8X’’dv = 13.5%


Ipk = 95.6 kA Isym = 23.8 kA a = 133.4 %

IscG

G


Generator-Source Short-Circuit Current


ac

dc

IIa2

=

Generator-Source Short-Circuit CurrentSurvey - Terminal Fault Prospective Currents (tcs = 40 ms)


Salient-pole machines usually have a lower degree ofasymmetry in case of generator-fed fault currents

Gas turbines of smaller power usuallyhave a higher degree of asymmetry

ABB is testing 130% degree of asymmetry

Out-of-Phase Conditions


110 kVSk = 10 GVA

100 MVA110/13.8 kV

uk = 12 %

99 MVA13.8 kV

cos j = 0.8X’’dv = 13.5%


Ipk = 68.2 kA Isym = 17.8 kA a = 117.2 %

Iop

G


Criteria of Selection and Technical RequirementsOut-of-Phase Conditions


ac

dc

IIa2

=


Influence of out-of-phase angle

Out-of-Phase Conditions

60° out-of-phase condition

180° out-of-phase condition 120° out-of-phase condition

90° out-of-phase condition

Selection of Generator Circuit-Breakers180° Out-of-Phase Synchronisation

© ABB GroupSeptember 17, 2016 |Slide 41

* Paper submitted to the International Conference of Power Systems Transients (IPST2013) in Vancouver (CA)

§Ratio between Isc OoP 180° and Isc system fault currents asfunction of generator rated power *

Example:

HECS-130 system source breaking current - 130 kA

OoP breaking current - 112 kA

Tests180° Out-Of-Phase Tests

September 17,2016

| Slide 42© ABB

§ Tests demonstrating the capability of a GCB to interruptcurrents resulting from 180° out-of-phase conditions shallshow

§ Current magnitude higher than 85% of system-sourceshort-circuit current;

§ Rate-of-rise of the transient recovery voltage (RRRV) ≥6.3 kV/ms.

§ A test performed with

§ Current magnitude equal to 50% of system-sourceshort-circuit current;

§ RRRV equal to 5.2 kV/ms or less;

is not a proof of the capability of the tested GCB to interruptcurrents resulting from 180° out-of-phase conditions .


Criteria of Selection and Technical RequirementsShort-Circuit Current Current Interruption

t [ms]50403020100-10-20-30-40

u (t)

i (t)



separation of arcing contact

Criteria of Selection and Technical RequirementsTransient Recovery Voltage (TRV)


Criteria of Selection and Technical RequirementsTransient Recovery Voltage (TRV) - Surge Capacitors

§ The capacitor is connectedduring the testing of theinterrupting performance

§ The capacitor is therefore to beconsidered as an integral partof a generator circuit-breaker


“The interrupting capability demonstrated by these tests isvalid only if capacitors of the same capacitance value asused during the tests are installed according to the tested

configuration.”

addition ofcapacitor

time delay increases with capacitance value

rate-of-rise decresaes with capacitance value

Criteria of Selection and Technical RequirementsSummary of Power Tests



ABB Portfolio Overview andCritical Design Aspects

ABB Generator Circuit BreakersPortfolio Overview (50/60 Hz)

© ABB


Generator Circuit-Breaker System typeHECS-130L


10

7

7

GCB SystemTypical single line diagram

Generator Circuit-Breaker

Series Disconnector

Capacitors

Starting Switch for SFC

Manual Short-Circuit Connection

Earthing Switches

Current Transformers

Potential Transformers

Surge Arresters

Motorized Short-Circuit Connection

G

1

2

3T

3G

6G

6T

5

4

8

8

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

9

9

Service during Tender and Project ExecutionApplication Studies Group for GCB’s


§ Application Studies Group is able to performany kind of calculation required for the properselection and verification of GCB’s.

§ Active in the Working Groups of the mainIEC/IEEE Standards for HV breakers.

§ Active in the revision of the IEEE C37.013 forGCB’s bringing the most significant experienceof ABB in the GCB field into requirements.

Critical Design AspectsGCB Cooling System


Natural Cooling Forced Cooling

ABB GCB portfolio

Critical Design AspectsGCB Cooling System


Natural Cooling Forced Cooling

EnhancedCooling

Important: Which ratio of the capability isdependent on the cooling system?

The fans provide a linear andeven distribution of air inorder to enhance natural

convection.

Critical Design AspectsIndependent Cooling and Breaking


• Cooling through air convection

• Failure of cooling does not influencebreaking capacity

• Less SF6

• Low maintenance

• High reliability

Cooling should not depend on SF6!


HECS-XLp, XXLpInnovative passive cooling by heat pipes

Latest technology patentedby ABB for natural cooling

and 20y maintenance free inaccordance with the overhaul

concept of HECS

Interrupting chamber designSF6/SF6 vs SF6/Air


SF6/SF6 contact systemused by ABB

arcing contacts

main contacts

SF6

SF6/Air contact systemnot used by ABB

arcing contacts

main contacts

disconnector

SF6

disconnector

§ Disconnector in series to arcing and main contacts§ Main contacts in SF6

§ «Disconnector» in series only to arcing contacs§ Main contacts in air

Commutation of current path from main contacts to arcingcontacts occurs in air.§Sparks which occur in air can lead to (commutation time 1.5-2 timeslonger :

I. a reduction of dielectric strength.II. wear of main contacts

§Problems of moisture and pollution when the air in IPB is at atmosphericpressure.

§ «Disconnector» visibility: main contacts and disconnector

§If circuit-breaker contacts accidentally close with disconnector open, nopossibility to extinguish arcs, risk of explosion à not safe !!

§ No isolation redundancy

Contact System Design


SF6/SF6 contact systemused by ABB

arcing contacts

main contacts

SF6

SF6/Air contact systemnot used by ABB

arcing contacts

main contacts

disconnector

SF6

Commutation of current path from main contacts to arcingcontacts occurs in SF6.§No sparks occur in air, thus eliminating the risk of a reduction ofdielectric strength.

§Problems of moisture and pollution when the air in IPB is atatmospheric pressure do not affect the safe operation.

§ Viewing windows of disconnector provide clear indication

§If circuit-breaker contacts accidentally close with disconnector open,no risk of explosion à safe !!

§ Isolation redundancy

disconnector

Design of Generator Circuit-BreakersContact System – SF6/SF6 v/s SF6/AirExample of specification

§ The circuit-breaker shall have two separate contact systems: one forcarrying load current, the other for arc interruption. Both contactsystems shall be contained in SF6 and the current commutationshall occur in SF6. Contacts in air are not acceptable. Currentcommutation in air is not acceptable.

§ A disconnector shall be provided on the transformer-side in serieswith the main and arcing contacts of the circuit-breaker. The seriesdisconnector must be able to isolate the entire circuit and allowisolation for maintenance using industry accepted practices.


Hydraulically charged spring operating mechanism

Critical Design AspectsOperating Mechanism

in all ABBapplications

Critical Design AspectsReliability of Operating Mechanism

§ According to CIGRE survey hydro-mechanical springmechanism is more reliable than full spring mechanism.

0.00

0.05

0.10

0.15

0.20

0.25

Hydro-mechanical spring *) Spring **) Pneumatic *)

Number of Major Failures per 100 CB-years

*) source: CIGRE Session 2012, paper A3-206

**) source: CIGRE Brochure 510: Final Report of the 2004 - 2007 InternationalEnquiry on Reliability of High Voltage Equipment - Part 2 Reliability of HighVoltage SF6 Circuit Breakers

Highest reliability ofhydro-mechanicalspring operating

mechanism

New Standard:IEC/IEEE 62271-37-013


History of Development of GCB Standard

1989IEEE StdC37.013-1989

1993IEEE StdC37.013-1993

1997IEEE StdC37.013-1997

2007IEEE StdC37.013a-2007

2008IEEE StdC37.013-1997(R2008)

2015

IEC/IEEE 62271-37-013

0

50

100

150

200

250

IEEE C37.013-1989 IEEE C37.013-1993 IEEE C37.013-1997 IEC/IEEE 62271-37-013

Number of pages of the document

More than double numberof pages compared to theprevious revision !!


New IEC/IEEE 62271-37-013

IEEE C37.013

IEEE C37.013a

IEC/IEEE 62271-37-013

New IEC/IEEE 62271-37-013Structure of the Document

§ IEC/IEEE Joint Development Procedure.

§ The document number IEC/IEEE 62271-37-013 results from merging thenumbering system of the twoorganizations.

§ Because IEC 62271 includes the use of“High-Voltage Switchgear andControlgear – Part xxx:”, this needs tobe part of the title.

§ Document is placed in the IEC template.

§Iscg = 100 kA

New IEC/IEEE 62271-37-013Generator-Source Short-Circuit Current Ratings

§ Iscg with 110% degree ofasymmetry

§ 0.74 x Iscg with 130%degree of asymmetry

§Class G1

§ Iscg with 130% degree ofasymmetry

§Class G2

§Degree of asymmery at contact separation irrespectively of the time that contact separationoccurs

rating is assigned bythe manufacturer

§100 kA @ 110%

§74 kA @ 130%

§100 kA @ 130%

§ A degree of asymmetry of 110% is not representative of interruptingconditions in actual power plant applications.

§ A degree of asymmetry of 130% is more appropriate.

§ Two classes for the rated generator-source short-circuit breaking currenthave been introduced:

§Most of ABB GCBsalready tested as G2 class!

New IEC/IEEE 62271-37-013Ratings – Mechanical Endurance

Two classes for the mechanical endurance have been introduced.

Standard generator circuit-breaker(normal mechanical endurance)

class M1

1000 operatingcycles

Generator circuit-breaker for special servicerequirements(extended mechanical endurance)

class M2

3000 operatingcycles

New IEC/IEEE 62271-37-013Type Tests

§ IEEE C37.013

× Test procedures are not alwayswell defined.

× This is especially true for tests inwhich the current exhibitsdelayed zero crossing.

× Customer cannot judge andevaluate objectively the validityof a test.

– § New IEC/IEEE 62271-37-013+

üA more detailed description oftest procedures is implemented.

üDetailed parameters are definedto characterize the currentwaveforms that should be tested.

üCustomer can easily judge andevaluate the validity of a test.

New IEC/IEEE 62271-37-013Type Tests – Delayed Current Zeros

Out-of-PhaseSynchronization

Generator TerminalFault

Fault at LV windingsof 3W Transformer

IEEE C37.013 IEC/IEEE 62271-37-013

New IEC/IEEE 62271-37-013Delayed Current Zeros

§ A test is not a sufficient proof of the breaking capability of the generatorcircuit-breaker with currents that exhibit delayed current zeros.

§ The test is required to derive the arc voltage vs current characteristics anddetermine the arc voltage model of the generator circuit-breaker.

§ The capability of the generator circuit-breaker to interrupt the current withdelayed zero crossings shall be ascertained by studies that take intoaccount the effect of the arc voltage..

“The capability of the generator circuit-breaker tointerrupt the current with delayed zero crossings shallbe ascertained by computations that consider theeffect of the arc voltage on the prospective short-circuit current.”

Source: IEC/IEEE 62271-37-013 Edition 1.0, 2015

New IEC/IEEE 62271-37-013Application Guide

The following studies shall be performed for each project:

§ system-source short-circuit current

§ generator-source short-circuit current

§ out-of-phase fault current


§ unloaded

§ loaded with leading p.f

§ Loaded with lagging p.f

effect of arcvoltage

UA = 0

UA = max

UA = 0

UA = max

effect of arcvoltage

SF6or

Vacuum


Application GuideInfluence of Capacitors - 3 Rules

1. The amount of equivalent capacitance required for breaking testsshall be given in the test report and on the nameplate.

2. The same capacitance value shall be used for all breaking tests.

3. The interrupting capability demonstrated by breaking tests is validonly if capacitors of the same capacitance value as used during thetests are installed in the generator circuit-breaker system deliveredfor a specific project.

Generator Circuit-BreakerDisconnectorEarthing switchStarting switchManually mounted short-circuiting connection

(1)(2)(3)(4)(5)

Surge capacitorCurrent transformerVoltage transformerSurge arresterMotor-operated short-circuiting link

(6)(7)(8)(9)

(10)

1 2

3 3

4 5

6 96

88

77

10

Single line diagram of a SF6 generator circuit-breaker


Pankaj KhaliTerritory Marketing & Sales Manager: India, Sub Regions & South East AsiaProduct Group: GCB , Power Grid Division –High Voltage ProductsABB India Limited

Phone: +912667676825Mobile: +919638288666, +919997576667

email: [email protected]

Subscribe for GCB Insights today - It's free

Question ………

Documents

Pankaj Khali, ABB India Limited Representing :ABB ... · PDF fileGenerator Circuit-Breakers Technical Seminar: PLN Pankaj Khali, ABB India Limited Representing :ABB Switzerland limited,