Pankaj Khali, ABB India Limited Representing :ABB Switzerland limited, September 2016 Generator Circuit-Breakers. Technical Seminar: PLN

Pankaj Khali, ABB India Limited Representing :ABB Switzerland limited, September 2016 Generator Circuit-Breakers Technical Seminar: PLN

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 September 17, 2016 Slide 2

Advantages of Generator Circuit-Breakers September 17, 2016 Slide 3

Introduction Unit connection (without Generator Circuit-Breaker) Connection with Generator Circuit-Breaker EHV HV EHV HV MT MT G UT ST GenCB UT ST AUX G AUX September 17, 2016 Slide 4

Introduction with Generator Circuit-Breaker EHV EHV MT MT UT UT GenCB GenCB G AUX G AUX September 17, 2016 Slide 5

Introduction without Generator Circuit-Breaker with Generator Circuit-Breaker EHV HV EHV MT MT G SS SFC AUX ST GenCB G SS SFC UT September 17, 2016 Slide 6 Typical Layouts for Gas Turbine Power Plants

Advantages of Generator Circuit-Breakers Simplified Operational Procedures Simplified operation procedures Improved protection Higher power plant availability During the starting-up or shutting-down of the generator only one circuit-breaker has to be operated thus reducing the number of switching operations necessary The responsibilities for the operation of the power plant and the high-voltage grid are clearly defined Economic benefits September 17, 2016 Slide 7

Advantages of Generator Circuit-Breakers Improved Protection Simplified operation procedures Improved protection Maximum selectivity of protection zones Rapid and selective clearance of all types of faults Bursting of the transformer tank following an internal fault in the main or unit transformer Higher power plant availability Economic benefits September 17, 2016 Slide 8

Advantages of Generator Circuit-Breakers Interruption of Generator-Fed Fault Currents Interruption of Generator-Fed Fault Currents Case without Generator Circuit-Breaker (Unit Connection) G I g I s Grid Fault Current I s +I g I g tens of ms Interruption of HV Circuit-Breaker seconds Time September 17, 2016 Slide 9

Advantages of Generator Circuit-Breakers Interruption of Generator-Fed Fault Currents Interruption of Generator-Fed Fault Currents Case with Generator Circuit-Breaker G I g I s Grid Fault Current I s +I g I g tens of ms seconds Interruption of HV of Generator Circuit-Breaker Circuit-Breaker Time September 17, 2016 Slide 10

Pressure Rise in Power Transformers P [bar] 2.5 2.0 1.5 1.0 0.5 HV Circuit-Breaker Generator Circuit-Breaker fault across bushing full winding shorted HV side tank withstand pressure Tap Changer fault to tank from HV winding tap changer contact fault 15% 25% 30% 10% shorted winding (portion) 50 100 150 200 250 t [ms] September 17, 2016 Slide 11

Equipment Failures Main Transformer Failures Sequence of events: t = 0 ms: earth fault at HV-side of transformer t = 45 ms: 2-phase short-circuit t = 95 ms: 3-phase short-circuit t 150 ms: explosion of transformer Generator Transformer Failure - without Generator Circuit-Breaker September 17, 2016 Slide 12

Advantages of Generator Circuit-Breakers Improved Protection Simplified operation procedures Improved protection Higher power plant availability Maximum selectivity of protection zones Rapid and selective clearance of all types of faults Bursting of the transformer tank following an internal fault in the main or unit transformer Thermal destruction of the generator damper winding due to short-time unbalanced load conditions Economic benefits September 17, 2016 Slide 13

Advantages of Generator Circuit-Breakers Short-Time Unbalanced Load Conditions Single and two phase faults Inverse component interacts with damper windings Critical mechanical and thermal stresses September 17, 2016 Slide 14

Equipment Failures Short-Time Unbalanced Load Conditions Unbalanced Load Condition without Generator Circuit-Breaker September 17, 2016 Slide 15

Advantages of Generator Circuit-Breakers Improved Protection Simplified operation procedures Improved protection Higher power plant availability Maximum selectivity of protection zones Rapid and selective clearance of all types of faults Bursting of the transformer tank following an internal fault in the main or unit transformer Thermal destruction of the generator damper winding due to short-time unbalanced load conditions Mechanical destruction of a turbine-generator set due to generator motoring Economic benefits September 17, 2016 Slide 16

Equipment Failures Generator Motoring - without Generator Circuit-Breaker Generator P n = 500 MW Main Transformer HV Circuit-Breaker Overhead Line (Transmission) GS 3~ Overhead Line Coupling Internal Open Mechanical command breakdown destruction at HV of circuit-breaker, turbine-generator pole set L1 Generator Three-phase Shaft and starts bearings network working are interruption destroyed as motor Speed Turbine-generator Generator is increasing is lifted unit out again is of running the foundation down normally 12 meter high explosive flame September 17, 2016 Slide 17

Equipment Failures Generator Motoring - without Generator Circuit-Breaker n [min -1 ] Critical Rotor Speed 3000 n [min -1 ] Object 2750 2500 2250 2000 1750 1500 1250 1000 750 500 2040 1800 after mechanical destruction 2420 Generator 2142 2010 1940 Turbine 1643 870 Generator normal run down 250 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 t [min] September 17, 2016 Slide 18

Advantages of Generator Circuit-Breakers Improved Protection Simplified operation procedures Improved protection Higher power plant availability Economic benefits Maximum selectivity of protection zones Rapid and selective clearance of all types of faults Bursting of the transformer tank following an internal fault in the main or unit transformer Thermal destruction of the generator damper winding due to short-time unbalanced load conditions Mechanical destruction of a turbine-generator set due to generator motoring Thermal/dynamic stress caused to the generator by synchronising under out-of-phase conditions September 17, 2016 Slide 19

Advantages of Generator Circuit-Breakers Higher Power Plant Availability Simplified operation procedures The rapid and selective clearance of all types of faults Improved protection Higher power plant availability Simplified operational procedures Increased Availability More reliable synchronisation Economic benefits The avoidance of changeover switching operations Unit auxiliaries supplies drawn directly from main grid September 17, 2016 Slide 20

Advantages of Generator Circuit-Breakers Economic Benefits Simplified operation procedures Improved protection Higher power plant availability Economic benefits Integration of all the associated items of switchgear into the generator circuit-breaker enclosure Possible to omit the station transformer and the associated high-voltage and medium-voltage switchgear The through-fault capability required of the unit transformers is substantially reduced Higher availability in turn leads to an increased number of the operating hours and therefore to a higher profit for the operator of the power plant September 17, 2016 Slide 21

Availability Calculation Layout of Power Station Reference Scenario Case 21 3 2 x 600 MW Power Station Layout Unit Connection with Generator Circuit -Breaker and Shut-Down Transformer September 17, 2016 Slide 22

Availability Calculation Results of Availability Calculation Results of Availability Calculation for one 600 MW Unit - Average Power Throughput 530 525 Average Power Output of Unit (Assumed Value) Power [MW] 520 515 510 505 Case 1 Case 2 Case 3 500 September 17, 2016 Slide 23

Criteria of Selection and Technical Requirements September 17, 2016 Slide 24

Criteria of Selection and Technical Requirements Duties of Generator Circuit-Breakers Synchronise the generator with the main system Separate the generator from the main system (switching off the unloaded/lightly loaded generator) Carry and interrupt load currents (up to the full load current of the generator) Interrupt system-source short-circuit currents Interrupt generator-source short-circuit currents Interrupt fault currents due to out-of-phase conditions up to out-ofphase angles of 180 September 17, 2016 Slide 25

Short-Circuit Current Interruption i (t) u (t) -40-30 -20-10 0 10 20 30 40 50 t [ms] separation of arcing contact Characteristics of short-circuit current Characteristics of transient recovery voltage (TRV) September 17, 2016 Slide 26

Criteria of Selection and Technical Requirements Requirements for Generator Circuit-Breakers i (t) u (t) Magnitude Asymmetry - 40-30 - 20-10 0 10 20 30 40 50 t [ms] Characteristics of short-circuit current Rate-of-rise High technical requirements are imposed on the circuitbreaker with respect to: Rated current Short-circuit currents (system-source and generatorsource) September 17, 2016 Slide 27 Characteristics of transient recovery voltage (TRV) Fault currents due to out-of-phase conditions Degree of asymmetry of fault currents, fault currents with delayed current zeros Rate-of-rise of the recovery voltages

Criteria of Selection and Technical Requirements Standards for Generator Circuit-Breakers IEC 62271-100 IEEE Std C37.013 / IEEE Std C37.013a Circuit-breakers that have been designed and tested in accordance with IEC 62271-100 do not meet the stringent requirements imposed on generator circuit-breakers and therefore are not suitable for the use as generator circuitbreakers. September 17, 2016 Slide 28

Criteria of Selection and Technical Requirements Selection of Generator Circuit-Breaker Rated maximum voltage Rated power frequency Rated insulation level (dielectric strength): Lightning impulse withstand 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) September 17, 2016 Slide 29

Selection 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 September 17, 2016 Slide 30

System-Source Short-Circuit Current 110 kv S k = 10 GVA 100 MVA 110/13.8 kv u k = 12 % I scts G 99 MVA 13.8 kv cos j = 0.8 X dv = 13.5% Contact parting time 50ms: I pk = 90.5 ka I sym = 33.2 ka a = 63.5 % September 17, 2016 Slide 31

System-Source Short-Circuit Current Characteristics of asymmetry: a = I dc 2I ac AC / symmetrical current 2I ac + DC current I dc = Asymmetrical current September 17, 2016 Slide 32

System-Source Short-Circuit Current Survey - Terminal Fault Prospective Currents (tcs = 40 ms) 250 I SCsys (karms) 200 150 100 50 0 0 500 1000 1500 2000 Generator Rated Power (MVA) September 17, 2016 Slide 33

System-Source Short-Circuit Current Survey - Terminal Fault Prospective Currents (tcs = 40 ms) 100 DOA sys (%) 80 60 40 20 0 0 500 1000 1500 2000 Generator Rated Power (MVA) Average DOA sys = 72.2% No DOA sys > 100% September 17, 2016 Slide 34

Generator-Source Short-Circuit Current 110 kv S k = 10 GVA 100 MVA 110/13.8 kv u k = 12 % I scg G 99 MVA 13.8 kv cos j = 0.8 X dv = 13.5% Contact parting time 50ms: I pk = 95.6 ka I sym = 23.8 ka a = 133.4 % September 17, 2016 Slide 35

Generator-Source Short-Circuit Current Characteristics of asymmetry: a = I dc 2I ac September 17, 2016 Slide 36

Generator-Source Short-Circuit Current Survey - Terminal Fault Prospective Currents (tcs = 40 ms) Gas turbines of smaller power usually have a higher degree of asymmetry Salient-pole machines usually have a lower degree of asymmetry in case of generator-fed fault currents ABB is testing 130% degree of asymmetry September 17, 2016 Slide 37

Out-of-Phase Conditions 110 kv S k = 10 GVA 100 MVA 110/13.8 kv u k = 12 % I op G 99 MVA 13.8 kv cos j = 0.8 X dv = 13.5% Contact parting time 50ms: I pk = 68.2 ka I sym = 17.8 ka a = 117.2 % September 17, 2016 Slide 38

Criteria of Selection and Technical Requirements Out-of-Phase Conditions Characteristics of asymmetry: a = I dc 2I ac September 17, 2016 Slide 39

Out-of-Phase Conditions Influence of outof-phase angle 180 out-of-phase condition 120 out-of-phase condition 90 out-of-phase condition 60 out-of-phase condition September 17, 2016 Slide 40

Selection of Generator Circuit-Breakers 180 Out-of-Phase Synchronisation Ratio between Isc OoP 180 and Isc system fault currents as function of generator rated power * * Paper submitted to the International Conference of Power Systems Transients (IPST2013) in Vancouver (CA) Example: HECS-130 system source breaking current OoP breaking current - 130 ka - 112 ka September 17, 2016 Slide 41

Tests 180 Out-Of-Phase Tests Tests demonstrating the capability of a GCB to interrupt currents resulting from 180 out-of-phase conditions shall show Current magnitude higher than 85% of system-source short-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-source short-circuit current; RRRV equal to 5.2 kv/ms or less; is not a proof of the capability of the tested GCB to interrupt currents resulting from 180 out-of-phase conditions. ABB September 17, 2016 Slide 42

Criteria of Selection and Technical Requirements Short-Circuit Current Current Interruption i (t) u (t) separation of arcing contact -40-30 -20-10 0 10 20 30 40 50 t [ms] September 17, 2016 Slide 43 Characteristics of short-circuit current Characteristics of transient recovery voltage (TRV)

Criteria of Selection and Technical Requirements Transient Recovery Voltage (TRV) September 17, 2016 Slide 44

Criteria of Selection and Technical Requirements Transient Recovery Voltage (TRV) - Surge Capacitors addition of capacitor The capacitor is connected during the testing of the interrupting performance rate-of-rise decresaes with capacitance value The capacitor is therefore to be considered as an integral part of a generator circuit-breaker time delay increases with capacitance value The interrupting capability demonstrated by these tests is valid only if capacitors of the same capacitance value as used during the tests are installed according to the tested configuration. September 17, 2016 Slide 45

Criteria of Selection and Technical Requirements Summary of Power Tests September 17, 2016 Slide 46

ABB Portfolio Overview and Critical Design Aspects September 17, 2016 Slide 47

ABB Generator Circuit Breakers Portfolio Overview (50/60 Hz) ABB

Generator Circuit-Breaker System type HECS-130L September 17, 2016 Slide 49

GCB System Typical single line diagram (1) Generator Circuit-Breaker 7 (2) Series Disconnector 9 (3) Capacitors 8 3 T (4) Starting Switch for SFC 6 T (5) Manual Short-Circuit Connection 5 2 (6) Earthing Switches 4 1 6 G 10 (7) (8) Current Transformers Potential Transformers 8 3 G (9) Surge Arresters 9 (10) Motorized Short-Circuit Connection 7 G September 17, 2016 Slide 50

Service during Tender and Project Execution Application Studies Group for GCB s Application Studies Group is able to perform any kind of calculation required for the proper selection and verification of GCB s. Active in the Working Groups of the main IEC/IEEE Standards for HV breakers. Active in the revision of the IEEE C37.013 for GCB s bringing the most significant experience of ABB in the GCB field into requirements. September 17, 2016 Slide 51

Critical Design Aspects GCB Cooling System Natural Cooling Forced Cooling September 17, 2016 Slide 52

ABB GCB portfolio

Critical Design Aspects GCB Cooling System The fans provide a linear and even distribution of air in order to enhance natural convection. Natural Cooling Forced Cooling Enhanced Cooling Important: Which ratio of the capability is dependent on the cooling system? September 17, 2016 Slide 54

Critical Design Aspects Independent Cooling and Breaking Cooling through air convection Failure of cooling does not influence breaking capacity Less SF6 Low maintenance High reliability Cooling should not depend on SF6! September 17, 2016 Slide 55

HECS-XLp, XXLp Innovative passive cooling by heat pipes Latest technology patented by ABB for natural cooling and 20y maintenance free in accordance with the overhaul concept of HECS September 17, 2016 Slide 56

Interrupting chamber design SF6/SF6 vs SF6/Air SF6/SF6 contact system used by ABB SF6/Air contact system not used by ABB main contacts SF6 arcing contacts disconnector main contacts SF6 arcing contacts disconnector Disconnector in series to arcing and main contacts Main contacts in SF6 «Disconnector» in series only to arcing contacs Main contacts in air September 17, 2016 Slide 57

Contact System Design SF6/SF6 contact system used by ABB SF6/Air contact system not used by ABB main contacts SF6 arcing contacts disconnector main contacts SF6 arcing contacts disconnector Commutation of current path from main contacts to arcing contacts occurs in SF6. No sparks occur in air, thus eliminating the risk of a reduction of dielectric strength. Problems of moisture and pollution when the air in IPB is at atmospheric 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 safe!! Isolation redundancy Commutation of current path from main contacts to arcing contacts occurs in air. Sparks which occur in air can lead to (commutation time 1.5-2 times longer : I. a reduction of dielectric strength. II. wear of main contacts Problems of moisture and pollution when the air in IPB is at atmospheric pressure. «Disconnector» visibility: main contacts and disconnector If circuit-breaker contacts accidentally close with disconnector open, no possibility to extinguish arcs, risk of explosion not safe!! No isolation redundancy September 17, 2016 Slide 58

Design of Generator Circuit-Breakers Contact System SF6/SF6 v/s SF6/Air Example of specification The circuit-breaker shall have two separate contact systems: one for carrying load current, the other for arc interruption. Both contact systems shall be contained in SF6 and the current commutation shall occur in SF6. Contacts in air are not acceptable. Current commutation in air is not acceptable. A disconnector shall be provided on the transformer-side in series with the main and arcing contacts of the circuit-breaker. The series disconnector must be able to isolate the entire circuit and allow isolation for maintenance using industry accepted practices.

Critical Design Aspects Operating Mechanism Hydraulically charged spring operating mechanism in all ABB applications September 17, 2016 Slide 60

Critical Design Aspects Reliability of Operating Mechanism According to CIGRE survey hydro-mechanical spring mechanism is more reliable than full spring mechanism. 0.25 Number of Major Failures per 100 CB-years Highest reliability of hydro-mechanical spring operating mechanism 0.20 0.15 0.10 0.05 0.00 Hydro-mechanical spring *) Spring **) Pneumatic *) *) source: CIGRE Session 2012, paper A3-206 **) source: CIGRE Brochure 510: Final Report of the 2004-2007 International Enquiry on Reliability of High Voltage Equipment - Part 2 Reliability of High Voltage SF6 Circuit Breakers

New Standard: IEC/IEEE 62271-37-013

History of Development of GCB Standard 2015 1989 IEEE Std C37.013-1989 1993 IEEE Std C37.013-1993 1997 IEEE Std C37.013-1997 2007 IEEE Std C37.013a-2007 250 200 150 100 2008 IEEE Std C37.013-1997 (R2008) Number of pages of the document More than double number of pages compared to the previous revision!! IEC/IEEE 62271-37-013 50 0 IEEE C37.013-1989 IEEE C37.013-1993 IEEE C37.013-1997 IEC/IEEE 62271-37-013 September 17, 2016 Slide 63

New IEC/IEEE 62271-37-013 IEC/IEEE 62271-37-013 IEEE C37.013 IEEE C37.013a September 17, 2016 Slide 64

New IEC/IEEE 62271-37-013 Structure of the Document IEC/IEEE Joint Development Procedure. The document number IEC/IEEE 62271-37-013 results from merging the numbering system of the two organizations. Because IEC 62271 includes the use of High-Voltage Switchgear and Controlgear Part xxx:, this needs to be part of the title. Document is placed in the IEC template.

New IEC/IEEE 62271-37-013 Generator-Source Short-Circuit Current Ratings A degree of asymmetry of 110% is not representative of interrupting conditions in actual power plant applications. A degree of asymmetry of 130% is more appropriate. Two classes for the rated generator-source short-circuit breaking current have been introduced: Class G1 Iscg = 100 ka Class G2 rating is assigned by the manufacturer Iscg with 110% degree of asymmetry 100 ka @ 110% 0.74 x Iscg with 130% degree of asymmetry 74 ka @ 130% Most of ABB GCBs already tested as G2 class! Iscg with 130% degree of asymmetry 100 ka @ 130% Degree of asymmery at contact separation irrespectively of the time that contact separation occurs

New IEC/IEEE 62271-37-013 Ratings Mechanical Endurance Two classes for the mechanical endurance have been introduced. Standard generator circuit-breaker (normal mechanical endurance) class M1 1000 operating cycles Generator circuit-breaker for special service requirements (extended mechanical endurance) class M2 3000 operating cycles

New IEC/IEEE 62271-37-013 Type Tests IEEE C37.013 New IEC/IEEE 62271-37-013 + Test procedures are not always well defined. A more detailed description of test procedures is implemented. This is especially true for tests in which the current exhibits delayed zero crossing. Detailed parameters are defined to characterize the current waveforms that should be tested. Customer cannot judge and evaluate objectively the validity of a test. Customer can easily judge and evaluate the validity of a test.

New IEC/IEEE 62271-37-013 Type Tests Delayed Current Zeros Generator Terminal Fault IEEE C37.013 IEC/IEEE 62271-37-013 Out-of-Phase Synchronization Fault at LV windings of 3W Transformer

New IEC/IEEE 62271-37-013 Delayed Current Zeros A test is not a sufficient proof of the breaking capability of the generator circuit-breaker with currents that exhibit delayed current zeros. The test is required to derive the arc voltage vs current characteristics and determine the arc voltage model of the generator circuit-breaker. The capability of the generator circuit-breaker to interrupt the current with delayed zero crossings shall be ascertained by studies that take into account the effect of the arc voltage.. The capability of the generator circuit-breaker to interrupt the current with delayed zero crossings shall be ascertained by computations that consider the effect of the arc voltage on the prospective shortcircuit current. Source: IEC/IEEE 62271-37-013 Edition 1.0, 2015

New IEC/IEEE 62271-37-013 Application Guide The following studies shall be performed for each project: system-source short-circuit current generator-source short-circuit current unloaded loaded with leading p.f Loaded with lagging p.f UA = 0 UA = max effect of arc voltage out-of-phase fault current September 17, 2016 Slide 71 UA = 0 UA = max effect of arc voltage SF6 or Vacuum

Application Guide Influence of Capacitors - 3 Rules 1. The amount of equivalent capacitance required for breaking tests shall 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 valid only if capacitors of the same capacitance value as used during the tests are installed in the generator circuit-breaker system delivered for a specific project. Single line diagram of a SF 6 generator circuit-breaker 4 5 8 8 7 1 2 7 3 3 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) Generator Circuit-Breaker Disconnector Earthing switch Starting switch Manually mounted short-circuiting connection Surge capacitor Current transformer Voltage transformer Surge arrester Motor-operated short-circuiting link September 17, 2016 Slide 72 6 10 6 9

Pankaj Khali Territory Marketing & Sales Manager: India, Sub Regions & South East Asia Product Group: GCB, Power Grid Division High Voltage Products ABB India Limited Phone: +912667676825 Mobile: +919638288666, +919997576667 email: Pankaj.khali@in.abb.com www.abb.com Subscribe for GCB Insights today - It's free Question September 17, 2016 Slide 73