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Bus Differential Protection Seminar June 2015 – AB/BC JC Theron

Bus Protection Seminar Jun2015

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Text of Bus Protection Seminar Jun2015

  • Bus Differential Protection Seminar June 2015 AB/BC

    JC Theron

  • GE Digital Energy Multilin

    Page 2 2015-01-15 Rev. 2 JCT

    Presentation Outline

    Introduction to Bus Protection

    Bus Arrangements and Components

    Protection Techniques

    CT Saturation

    High Impedance Bus Differential Protections

    Low Impedance Bus Differential Protections

  • GE Digital Energy Multilin

    Page 3 2015-01-15 Rev. 2 JCT

    Presentation Outline

    GEs Multilin Bus Protection Portfolio

    B30, B90 & B95Plus Application Considerations

    Advanced Application Topics

    B90 & B95Plus Application Examples

  • GE Digital Energy Multilin

    Page 4 2015-01-15 Rev. 2 JCT

    Introduction to Bus Protection

  • GE Digital Energy Multilin

    Page 5 2015-01-15 Rev. 2 JCT

    Challenges to Bus Zone Protection

    High Fault Current Levels

    Large dynamic forces can place mechanical stress on busbars and result in physical damage to equipment therefore fast clearing times are required.

    High fault currents can lead to CT saturation, particularly for external faults, which may lead to mal-operation of the bus protection.

    Mal-Operation of Bus Protections Have Significant Impact

    Loss of customer loads may damage both customer assets as well as customer perception of the utility.

    Detrimental impact on industrial processes

    System voltage levels and corresponding system stability may be adversely affected.

    Best Case: Remedial Action Schemes (load shedding)

    Worst Case: Partial or Total System Collapse (wide-spread blackout)

    Bus Protection Must be Dependable and Secure, With Emphasis on Security

  • GE Digital Energy Multilin

    Page 6 2015-01-15 Rev. 2 JCT

    Challenges to Bus Zone Protection Continued

    Many Different Bus Topologies

    Many switchyard configurations possible.

    Many different CT placements possible.

    Single Bus, Double Bus (Single and Double Breaker), Main and Transfer Bus, Breaker-and-a-Half and hybrids

    Buses may Reconfigure at Any Time

    Different apparatus may be connected/disconnected from a given bus.

    Switching may happen from any number of sources

    Manually from human operator action (e.g. equipment maintenance)

    Automatically from other protections, Wide-Area Special Protections, Remedial Action Schemes, Auto-Restoration/Auto-Transfer Schemes

    Bus Protection Must Adapt Automatically (No User Intervention) and in Real-Time, Based on Bus Configuration

  • GE Digital Energy Multilin

    Page 7 2015-01-15 Rev. 2 JCT

    Arc flash energy reduction:

    Relay operating times of 12 24 mS will reduce energy to level 2 in most MV cases

    No impact on system coordination

    Always in operation without any special action required by workers

    Faster return to service following a bus fault:

    Fast operating time minimizes physical damage

    Shorter repair times

    High-Speed Bus Protection Advantages

  • GE Digital Energy Multilin

    Page 8 2015-01-15 Rev. 2 JCT

    Seeing increased specification of bus differential on LV switchgear for arc flash mitigation CT performance is usually too poor for true bus differential

    Limited space for hi C-rated CTs

    Very high available SC currents (50 60 KA typical)

    No notable advantage of high versus low impedance differential

    Zone selective interlock is best current solution

    May see non-iron core current sensor technology in future

    Rogowski coils

    Fiber optic sensors

    Low Voltage Bus Differential

  • GE Digital Energy Multilin

    Page 9 2015-01-15 Rev. 2 JCT

    Bus Arrangements and Components

  • GE Digital Energy Multilin

    Page 10 2015-01-15 Rev. 2 JCT

    1 2 3 n-1 n

    ZONE 1

    - - - -

    Distribution and lower transmission voltage levels

    No operating flexibility Fault on the bus trips all circuit

    breakers

    ZONE 1ZONE 2

    Lower transmission voltages Limited operating flexibility

    ZONE 1

    ZONE 2

    Very common arrangement at US West Coast substations

    Transmission and distribution voltage levels

    Breaker maintenance without circuit removal

    Fault on a bus disconnects only the circuits being connected to that bus

    Multiple bus sections - single breaker with bus tie

    Single bus - single breaker

    Double bus - single breaker with bus tie

  • GE Digital Energy Multilin

    Page 11 2015-01-15 Rev. 2 JCT

    Typical Industrial Single Bus

  • GE Digital Energy Multilin

    Page 12 2015-01-15 Rev. 2 JCT

    Typical Industrial Double Bus

  • GE Digital Energy Multilin

    Page 13 2015-01-15 Rev. 2 JCT

    ZONE 1

    ZONE 2

    Very high operating flexibility Transfer bus for breaker

    maintenance

    ZONE 1

    MAIN BUS

    TRANFER BUS

    Increased operating flexibility A bus fault requires tripping all

    breakers Transfer bus for breaker

    maintenance

    Main and Transfer buses

    Double bus single breaker with transfer bus

  • GE Digital Energy Multilin

    Page 14 2015-01-15 Rev. 2 JCT

    ZONE 1

    ZONE 2

    High operating flexibility Line protection covers the part

    between two CTs Fault on a bus does not disturb

    the power of the circuits

    ZONE 1

    ZONE 2

    Used on higher voltage levels More operating flexibility Requires more breakers Middle sections covered by the

    line protection

    Double bus - double breaker

    Breaker-and-a-half bus

  • GE Digital Energy Multilin

    Page 15 2015-01-15 Rev. 2 JCT

    Higher voltage levels High operating flexibility with

    minimum breakers Separate bus protection not

    required, as the line protections cover overlap bus parts

    B1 B2

    TB1

    L1 L2

    L3 L4

    TB1

    Ring bus

  • GE Digital Energy Multilin

    Page 16 2015-01-15 Rev. 2 JCT

    Bus Components

    BUS 1

    BUS 2

    ISO4

    CB 2

    CT2

    C2

    ISO5

    ISO1

    CB 1

    CT1

    C1

    ISO2

    ISO 3

    CT12

    CT13

    CB 12

    CB 11 CT11

    CT10CB 10

    ISO25

    CB 9

    CT9

    C9

    ISO26

    ISO28

    ISO29

    ISO 6 ISO27

    Feeder isolators

    Feeder breaker

    Feeder CTs

  • GE Digital Energy Multilin

    Page 17 2015-01-15 Rev. 2 JCT

    Bus Components

    BUS 1

    BUS 2

    ISO4

    CB 2

    CT2

    C2

    ISO5

    ISO1

    CB 1

    CT1

    C1

    ISO2

    ISO 3

    CT12

    CT13

    CB 12

    ISO25

    CB 9

    CT9

    C9

    ISO26

    ISO28

    ISO29

    ISO 6 ISO27

    CT11CB 11

    CT10CB 10

    Section breakers

    Section breaker CTs

    Coupler breaker isolators

    Coupler breaker

    Coupler breaker CTs

  • GE Digital Energy Multilin

    Page 18 2014-09-15 Rev. 1 JCT

    Protection Techniques

  • GE Digital Energy Multilin

    Page 19 2015-01-15 Rev. 2 JCT

    Bus Zone Protection Techniques

    Various existing implementations:

    Unrestrained Differential

    Interlocking/Blocking Schemes

    High Impedance Differential

    Low Impedance Percent Differential

    All Bus Zone protections essentially operate based on Kirchoffs Law for Currents:

    The sum of all currents entering a node must equal zero.

    The only variation is on how this is implemented.

  • GE Digital Energy Multilin

    Page 20 2015-01-15 Rev. 2 JCT

    Unrestrained Differential (Overcurrent)

    Differential current created by physically summing CTs

    CT ratio matching required (auxiliary CTs)

    External faults may cause CT saturation, leading to spurious differential currents in the bus protection

    Intentional time delay added to cope with CT saturation effects

    Unrestrained differential function useful for microprocessor-based protections (check zone)

    51

    Intentional Time Delay means No Fast Zone Clearance

  • GE Digital Energy Multilin

    Page 21 2015-01-15 Rev. 2 JCT

    Interlocking/Blocking Schemes

    Blocking signals generated by downstream protections (usually instantaneous overcurrent)

    Simple inst. overcurrent protection with short intentional time delay

    Need to wait for blocking signals

    Usually inverse timed backup provided

    Timed backup may be tricked by slow clearance of downstream faults.

    Blocking can be done via hardwire or communications (e.g GSSE/GOOSE, dedicated communications)

    Technique Limited to Radial Circuits with Negligible Backfeed

    50

    50 50 50 50 50

    BL

    OC

    K

  • GE Digital Energy Multilin

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    High Impedance Differential (Overvoltage)

    Operating signal created by connecting all CT secondaries in parallel

    CTs must all have the same ratio

    Must have dedicated CTs

    Overvoltage element operates on voltage developed across resistor connected in secondary circuit

    Requires varistors or AC shorting relays to limit energy during faults

    Accuracy dependent on secondary circuit resistance

    Usually requires larger CT cables to reduce errors higher cost

    Cannot Easily be Applied to Reconfigurable Buses and Offers no Advanced Functionality (Oscillography, Breaker Fail).

    59

  • GE Digital Energy Multilin

    Page 23 2015-01-15 Rev. 2 JCT

    High

    Impedance Bus Differential

    Relay

    CB n CB 3 CB 2 CB 1

    I1 I2 I3 In

    i1

    i2

    i3

    in

    I1 + I2 + I3 + + In = Id = 0 The vectorial sum of all primary currents in and out of the bus equals zero

    i1 + i2 + i3 + . + in = id = 0 The vectorial sum of all CT secondary currents (assuming same CT ratio and no CT saturation) in and out of the bus equals zero

    v1 +v2 + v3 + + vn = vd = 0 The vectorial sum of all voltages induced on all CT secondary windings during normal load or external fault (no CT saturation) equals zero

    vd = 0

    id = 0

    None of the above equations hold true during internal fault or external fault with CT saturation

    + - - +

    High Impedance Bus Protection - General Philosophy

  • GE Digital Energy Multilin

    Page 24 2015-01-15 Rev. 2 JCT

    High Impedance Differential (Overvoltage/current)

    Operating signal created by connecting all CT secondaries in parallel

    CTs same ratio, class, saturation curve and burden (including same CT leads)

    Must have dedicated CTs

    Overvoltage element operates on voltage across resistor in secondary circuit

    Requires varistors and/or AC shorting relays to limit

    energy during faults

    Model HID32

    or HID31

    B30 Relay

  • GE Digital Energy Multilin

    Page 25 2015-01-15 Rev. 2 JCT

    High Impedance Differential (Overvoltage/current) Settings Calculations

    Operating signal measured can be Voltage or Current: Voltage:

    Current:

    Where VS = pickup setting of voltage element (if voltage is used)

    IR = pickup setting of the current differential element (if current is used)

    RS = DC Resistance of fault CT secondary windings and leads to terminals.

    RL = single conductor DC resistance of CT cable for one way run from CT housing terminal to measuring element

    P = 1 for three phase faults; 2 for single phase to ground faults

    IF = external fault current primary RMS value

    N = CT ratio

    1.6 = margin factor

    RE = stabilizing resistance (2000 Ohm if the HID is used)

  • GE Digital Energy Multilin

    Page 26 2015-01-15 Rev. 2 JCT

    Low Impedance Percent Differential

    Individual currents sampled by protection and summated digitally CT ratio matching done internally (no auxiliary CTs)

    Dedicated CTs not necessary

    Additional algorithms improve security of percent differential characteristic during CT saturation

    Dynamic bus replica allows application to reconfigurable buses Done digitally with logic to add/remove current inputs from differential computation

    Switching of CT secondary circuits not required

    Low secondary burdens

    Additional functionality available without additional devices Digital oscillography

    Time-stamped event recording

    Breaker Failure

    Can be Applied to Reconfigurable Buses and Secure from CT Saturation, with Additional Useful Functionality.

  • GE Digital Energy Multilin

    Page 27 2015-01-15 Rev. 2 JCT

    Digital Differential Algorithm Goals

    Improve the main differential algorithm operation

    Better filtering

    Faster response

    Better restraint techniques

    Switching transient blocking

    Provide dynamic bus replica for reconfigurable busbars

    Dependably detect CT saturation in a fast and reliable manner, especially for external faults

    Apply additional security to the main differential algorithm to prevent incorrect operation

    External faults with CT saturation

    CT secondary circuit trouble (e.g. short circuits)

  • GE Digital Energy Multilin

    Page 28 2015-01-15 Rev. 2 JCT

    CT Saturation

  • GE Digital Energy Multilin

    Page 29 2015-01-15 Rev. 2 JCT

    CT Saturation Concepts

    CT saturation depends on a number of factors

    Physical CT characteristics (size, rating, winding resistance, saturation voltage)

    Connected CT secondary burden (wires + relays)

    Primary current magnitude, DC offset (system X/R)

    Residual flux in CT core

    Actual CT secondary currents may not behave in the same manner as the ratio (scaled primary) current during faults

    End result is spurious differential current appearing in the summation of the secondary currents which may cause differential

    elements to operate if additional security is not applied

  • GE Digital Energy Multilin

    Page 30 2015-01-15 Rev. 2 JCT

    CT Saturation

    Ratio Current CT Current

    Ratio Current CT Current

    No DC Offset

    Waveform remains fairly symmetrical

    With DC Offset

    Waveform starts off being asymmetrical, then symmetrical in steady state

  • GE Digital Energy Multilin

    Page 31 2015-01-15 Rev. 2 JCT

    CT Saturation External Fault with Ideal CTs

    Fault starts at t0

    Steady-state fault conditions occur at t1

    diffe

    ren

    tia

    l

    restrainingt0

    t1

    Ideal CTs have no saturation or mismatch thus produce no differential current

  • GE Digital Energy Multilin

    Page 32 2015-01-15 Rev. 2 JCT

    CT Saturation External Fault with Actual CTs

    Fault starts at t0

    Steady-state fault conditions occur at t1

    diffe

    ren

    tia

    l

    restrainingt0

    t1

    Actual CTs do introduce errors thus produce some differential current (without CT saturation)

  • GE Digital Energy Multilin

    Page 33 2015-01-15 Rev. 2 JCT

    CT Saturation External Fault with CT Saturation

    Fault starts at t0, CT begins to saturate at t1

    CT fully saturated at t2

    diffe

    ren

    tia

    l

    restrainingt0

    t1

    t2

    CT saturation causes increasing differential current that may enter the differential element operate region.

    t0 fault inception t1 CT saturation time t2 CT saturated

  • GE Digital Energy Multilin

    Page 34 2015-01-15 Rev. 2 JCT

    Some Methods of Securing Bus Differential

    Block the bus differential for a period of time (intentional delay)

    Increases security as bus zone will not trip when CT saturation is present

    Prevents high-speed clearance for internal faults with CT saturation or evolving faults

    Change settings of the percent differential characteristic (usually Slope 2)

    Improves security of differential element by increasing the amount of spurious differential current needed to incorrectly trip

    Difficult to explicitly develop settings (Is 60% slope enough? Should it be 75%?)

    Apply directional (phase comparison) supervision

    Improves security by requiring all currents flow into the bus zone before asserting the differential element

    Easy to implement and test

    Stable even under severe CT saturation during external faults

  • GE Digital Energy Multilin

    Page 35 2015-01-15 Rev. 2 JCT

    High Impedance vs Low Impedance Bus Protection

  • MDS WiYZTM Bus Protection Applications

    High Impedance Low Impedance

    Pros Different CT ratios and classes can be used CTs can be shared with other devices With CT Saturation Detection & Directionality

    check; Robust on External Faults with CT

    Saturation

    CT Supervision/monitoring available Additional protection functions available on per-

    feeder basis (50/51/50N/51N, 59 and Breaker Fail)

    Multiple tripping contacts available No Stabilizing Resistors or Varistor/Metrosils

    needed

    Dynamic Bus Replica Available IED-functionalities eg SOE, waveform capture Always self-monitored; less maintenance required

    Cons Slower than High Impedance, however sub-cycle Dedicated CT Saturation Detection required Settings more complicated Schemes can get very complicated for

    large/double busses with Breaker Fail

    Pros Used for years wide familiarity (Setting &

    Testing)

    Exceptional performance External faults with CT Saturation

    Low Cost Simple to Set Easy to expand scheme Fast Operating Times for Internal Faults Better in cases with High range of Fault Current

    Cons Identical CT ratios, class required (Same B/H &

    knee-point voltage) (Cost)

    CTs not to be shared with other higher-VA devices dedicated CTs (Potential Cost)

    Stabilizing resistors and/or Varistor Metrosils required (Cost & Safety)

    Zone selection/switching (Bus Replica) not possible External contact multiplication required No IED-functionalities eg. No capture of Separate

    waveforms, events, no communications

    Mostly Unmonitored E/M relays without self-checking more regular maintenance required

  • GE Digital Energy Multilin

    Page 37 2015-01-15 Rev. 2 JCT

    GEs Multilin Bus Protection Portfolio

  • GE Digital Energy Multilin

    Page 38 2015-01-15 Rev. 2 JCT

    GE Multilin Bus Differential Relays

    High Impedance Differential

    PVD (Electromechanical)

    MIB II (single function digital relay)

    HID (high impedance module with UR-series (B30))

    Low Impedance Digital Differential

    B30

    B90

    B95Plus

    B30, B90 and B95Plus have a great deal in common, but do have some significant differences as well

  • GE Digital Energy Multilin

    Page 39 2015-01-15 Rev. 2 JCT

    Electro-mechanical Work-horse:

    Fast: typical operating time of 16 30 mS Phase packaged (3 required) 100s of thousands in service Still available (expensive) Aging fleet will need replacing due to capacitor failures

    High Impedance Bus Protection (PVD)

  • GE Digital Energy Multilin

    Page 40 2015-01-15 Rev. 2 JCT

    Comprised of the following:

    High-Speed overcurrent module: Differential protection for up to 3

    differential currents (phases). High Impedance Module (HID) with Stabilizing Resistors and Voltage Limiters

    The high speed overcurrent relay connected in series with the stabilizing resistors provides high speed operation for bus faults involving high-magnitude currents. A voltage limiting element (MOV) is connected in

    parallel to avoid excessively high CT secondary voltages that can damage the current inputs after relay operation.

    Lockout Relay & Push Button: Mechanical lockout after relay operation and Reset Button. Lockout contacts short CT secondaries. Four additional normally open contacts available for use

    High Impedance Bus Protection (MIB)

  • GE Digital Energy Multilin

    Page 41 2015-01-15 Rev. 2 JCT

    Comprised of the following:

    B30 Relay (alternate: 850)- high speed overcurrent relay (check sensitivity). High Impedance Module (HID) with Stabilizing Resistors and Voltage Limiters

    The B30 relay (high speed overcurrent relay) connected in series with the stabilizing resistors provides high speed operation for bus faults involving high-magnitude currents. A voltage limiting element (MOV) is connected in parallel to avoid excessively high CT secondary voltages that can damage the current inputs after relay operation.

    Lockout Relay & Push Button: Mechanical lockout after relay operation and Reset Button. Lockout contacts short CT secondaries. Four additional normally open contacts available for use.

    +

    B30 Relay HID Module

    High Impedance Bus Protection (B30 + HID)

  • GE Digital Energy Multilin

    Page 42 2015-01-15 Rev. 2 JCT

    Low Impedance Protection: B30 & B90 vs B95Plus

    B30 & B90 are members of the Universal Relay (UR) family Common hardware & software

    Common added features

    Common communications interfaces & protocols

    User Programmable Logic (FlexLogic)

    B95Plus based on URPlus hardware platform

    High Performance (All) Typical Response Time: 12 msec + output contact

    Max. Response Time: 16 msec + output contact

    Secure for external faults with severe CT saturation

    All use the same proven algorithms for ratio compensation, dynamic bus replication, differential calculations, CT saturation detection and differential element security

    Proven Hardware. Proven Algorithms.

  • GE Digital Energy Multilin

    Page 43 2015-01-15 Rev. 2 JCT

    B30 & B90 What is Different

    B30 provides three-phase bus differential protection in a single hardware chassis

    All three phase currents from all feeders are connected to a single chassis with multiple DSPs (1 zone), with phase segregation done in software only.

    Limited to 6 three-phase current sources (or five current sources and one three-phase voltage source)

    Up to six breaker failure elements included

    B90 provides hardware-segregated bus differential protection in one or more hardware chassis

    DSP modules configured for up to 8 currents (7 currents & 1 voltage) for a single phase

    Phase segregation by hardware and software configuration

    Minimum configuration: 8 feeders in a single chassis with three DSP modules (4 zones)

    Maximum configuration: 24 feeders in three chassis, each with 3 DSPs (4 zones)

    Additional I/O, additional Logic, optional breaker failure available

    B30 Cost effective protection & metering. B90 Comprehensive and scalable protection.

  • GE Digital Energy Multilin

    Page 44 2015-01-15 Rev. 2 JCT

    52

    DAU

    52

    DAU

    52

    DAU

    CU

    copper

    fiber

    Distributed Architecture (B95+):

    Data Acquisition Units in the bays

    Central Unit processing all the data

    Fiber for communication

    Sampling synchronization by CU

    Easily expanded

    52 52 52

    CU

    copper

    Centralized Architecture (B30, B90):

    Central Unit processing all the data

    Traditional copper cables

    CT lead length limitation

    Centralized architecture Distributed Architecture

    Bus Protection

  • GE Digital Energy Multilin

    Page 45 2015-01-15 Rev. 2 JCT

    MAIN PROTECTION

    Two Bus Differential (87B) zones:

    Restrained and Unrestrained (instantaneous)

    Dynamic Bus Replica

    Phase IOCs (2 elements only for external check zone and supervision)

    VOLTAGE SUPERVISION

    Phase Undervoltage (27P)

    Neutral & Auxiliary Overvoltage (59N & X)

    BACKUP

    Phase, Neutral & Ground TOCs (per feeder)

    OTHER

    Breaker Failure per breaker

    CT Trouble (50/74)

    FlexElementsTM

    Power metering (FW 7.3x)

    B30 Protection Features (up to 6 circuits)

  • GE Digital Energy Multilin

    Page 46 2015-01-15 Rev. 2 JCT

    B30 Bus Differential Protection - Wiring

  • GE Digital Energy Multilin

    Page 47 2015-01-15 Rev. 2 JCT

    Up to 96 digital inputs per B90 IED

    Up to 48 output contacts per B90 IED

    Flexible allocation of AC inputs, digital inputs and output contacts between the B90 IEDs

    B90 Low Impedance Bus Protection

    24 Circuit Applications

    Up to 24 circuits in a single zone without voltage supervision

    Multi-IED architecture with each IED built on modular hardware (single to multiple chassis)

  • GE Digital Energy Multilin

    Page 48 2015-01-15 Rev. 2 JCT

    MAIN PROTECTION

    Four Bus Differential zones:

    Restrained (87B)

    Unrestrained/instantaneous (50/87)

    Dynamic Bus Replica

    VOLTAGE SUPERVISION

    Phase Undervoltage (27P)

    BACKUP

    Phase TOC (51) - per feeder

    Phase IOCs (50) - per feeder

    OTHER

    Breaker Failure per breaker (50BF)

    CT Trouble (50/74)

    B90 Protection Features

  • GE Digital Energy Multilin

    Page 49 2015-01-15 Rev. 2 JCT

    8 Circuit Applications

    B90 Low Impedance Bus Protection

    Different CT Ratio Capability for Each Circuit

    Largest CT Primary is Base in Relay

    24 Current Inputs 4 Zones

    Zone 1 = Phase A Zone 2 = Phase B Zone 3 = Phase C Zone 4 = Not used

  • GE Digital Energy Multilin

    Page 50 2015-01-15 Rev. 2 JCT

    Relay 1 - 24 Current Inputs 4 Zones

    Zone 1 = Phase A (12 currents) Zone 2 = Phase B (12 currents) Zone 3 = Not used Zone 4 = Not used

    CB 12 CB 11

    Relay 2 Up to 24 Current Inputs 4 Zones

    Zone 1 = Not used Zone 2 = Not used Zone 3 = Phase C (12 currents) Zone 4 = Possibly used for ground TOC

    backup

    12 Circuit Applications

    B90 Low Impedance Bus Protection

    Different CT Ratio Capability for Each Circuit Largest CT Primary is Base in Relay

  • GE Digital Energy Multilin

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    B90 Bus Differential Protection - Wiring

  • GE Digital Energy Multilin

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    MAIN PROTECTION

    Uses Merging Units (BRICKs)

    Six Bus Differential zones: Restrained (87B) Unrestrained/instantaneous (50/87) Dynamic Bus Replica

    VOLTAGE SUPERVISION

    Phase Undervoltage (27P)

    BACKUP

    Phase TOC (51)- per feeder

    Phase IOCs (50)

    OTHER

    Breaker Failure per bkr (50BF)

    CT Trouble (50/74)

    B95Plus Protection Features

    Reconfigurable multi-section busbar - up to 24 feeders in one chassis

  • GE Digital Energy Multilin

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    B95Plus System Architecture

  • GE Digital Energy Multilin

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    B95Plus Bus Differential Protection - Wiring

  • GE Digital Energy Multilin

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    B95Plus Bus Differential Protection - Wiring

  • GE Digital Energy Multilin

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    B95Plus Bus Differential Protection - Wiring

  • Configuration of Bus Differential (87B)

  • GE Digital Energy Multilin

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    Configuring the Bus Differential Zone

    1. Configure the physical CT Inputs CT Primary and Secondary values

    Both 5 A and 1 A inputs are supported by the UR hardware (NOT by Brick!)

    Ratio compensation done automatically for CT ratio differences up to 32:1

    2. Configure AC Signal Sources (B30 and B95Plus)

    3. Configure Bus Zone with Dynamic Bus Replica

    Bus Zone settings defines the boundaries of the Differential Protection and CT Trouble Monitoring.

  • GE Digital Energy Multilin

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    The Dynamic Bus (Example 1)

    NORTH BUS

    SOUTH BUS

    CT-7

    CT-8

    B-7

    B-5

    B-6

    CT-5

    CT-6

    S-5

    S-6

    B-4CT-4

    S-3

    S-4

    B-3CT-3

    S-1

    S-2

    B-2CT-2CT-1

    B-1

    C-1 C-2 C-4

    C-3 C-5

  • GE Digital Energy Multilin

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    The Dynamic Bus Replica B30 Configuration (Example 1)

    Bus Zone Source A CT-1

    Bus Zone Status A On (Always Included in Bus Zone)

    Bus Zone Source B CT-2

    Bus Zone Status B S-1 (Only Included in Bus Zone if S-1 Closed)

    Bus Zone Source C CT-3

    Bus Zone Status C S-3

    Bus Zone Source D CT-4

    Bus Zone Status D S-5

    Bus Zone Source E CT-5

    Bus Zone Status E On

    Bus Zone Source F CT-8

    Bus Zone Status F On

  • GE Digital Energy Multilin

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    Bus Differential Block Diagram

  • GE Digital Energy Multilin

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    Definitions of Restraint Signals

    maximum of

    geometrical average

    scaled sum of

    sum of nR iiiii ...321

    nR iiiin

    i ...1

    321

    nR iiiiMaxi ,...,,, 321

    nnR iiiii ...321

  • GE Digital Energy Multilin

    Page 63 2015-01-15 Rev. 2 JCT

    Sum Of Versus Max Of Restraint Methods

    Sum Of Approach

    More restraint on external faults; less sensitive for internal faults

    Scaled-Sum Of approach takes into account number of connected circuits and may increase sensitivity

    Breakpoint settings for the percent differential characteristic more difficult to set

    Max Of Approach

    Less restraint on external faults; more sensitive for internal faults

    Breakpoint settings for the percent differential characteristic easier to set

    Better handles situation where one CT may saturate completely (99% slope settings possible)

    B30, B90 (and UR in General) and B95Plus Use the Max Of Definition for Restraint Quantities.

  • GE Digital Energy Multilin

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    Bus Differential Adaptive Approach d

    iffe

    ren

    tia

    l

    restraining

    Region 1

    (low differential

    currents)

    Region 2

    (high differential

    currents)

    Region 1 (DIFL)

    Low current magnitudes

    CT saturation unlikely, due to DC offset

    Region 2 (DIFH)

    High current magnitudes Quick CT saturation likely

    CT saturation easy to detect

  • GE Digital Energy Multilin

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    Bus Differential Adaptive Logic Diagram

    DIFL

    DIR

    SAT

    DIFH

    OR

    AN

    D

    OR

    87B BIASED OP

    AN

    D

  • GE Digital Energy Multilin

    Page 66 2015-01-15 Rev. 2 JCT

    Phase Comparison Principle Continued

    BLOCK

    OPERATE

    BLOCK

    pD

    p

    II

    Ireal

    pD

    p

    II

    Iimag

    Ip

    ID

    - Ip

    External Fault Conditions

    OPERATE

    BLOCK

    BLOCK

    pD

    p

    II

    Ireal

    pD

    p

    II

    Iimag

    Ip

    ID

    - Ip

    Internal Fault Conditions

    OPERATE

    OPERATE

    Secondary Current of

    Faulted Circuit

    (Severe CT Saturation)

    No Voltages are required or needed

  • GE Digital Energy Multilin

    Page 67 2015-01-15 Rev. 2 JCT

    CT Saturation Redux

    Fault starts at t0, CT begins to saturate at t1

    CT fully saturated at t2

    diffe

    ren

    tia

    l

    restrainingt0

    t1

    t2

  • GE Digital Energy Multilin

    Page 68 2015-01-15 Rev. 2 JCT

    CT Saturation Detector Operating Principles

    The 87B SAT flag WILL NOT be set during internal faults, regardless of whether or not any of the CTs saturate.

    The 87B SAT flag WILL be set during external faults, regardless of whether or not any of the CTs saturate.

    By design, the 87B SAT flag WILL force the relay to use the additional 87B DIR phase comparison for Region 2

    The Saturation Detector WILL NOT Block the Operation of the Differential Element it will only Force 2-out-of-2 Operation

  • GE Digital Energy Multilin

    Page 69 2015-01-15 Rev. 2 JCT

    CT Saturation Detector - Examples

    The oscillography records on the next two slides were captured from a B30 relay under test on a real-time digital power system simulator

    First slide shows an external fault with deep CT saturation (~1.5 msec of good CT performance)

    SAT saturation detector flag asserts prior to BIASED PKP bus differential pickup

    DIR directional flag does not assert (one current flows out of zone), so even though bus differential picks up, no trip results

    Second slide shows an internal fault with mild CT saturation

    BIASED PKP and BIASED OP both assert before DIR asserts

    CT saturation does not block bus differential

    More examples available (COMTRADE files) upon request

  • GE Digital Energy Multilin

    Page 70 2015-01-15 Rev. 2 JCT

    The bus differential

    protection element

    picks up due to heavy

    CT saturation

    The CT saturation flag

    is set safely before the

    pickup flag

    The

    directional flag

    is not set

    The element

    does not

    maloperate

    Despite heavy CT saturation the external fault current is seen in the opposite direction

    CT Saturation Example External Fault

    0.06 0.07 0.08 0.09 0.1 0.11 0.12 -200

    -150

    -100

    -50

    0

    50

    100

    150

    200

    time, sec

    cu

    rre

    nt,

    A

    ~1 ms

  • GE Digital Energy Multilin

    Page 71 2015-01-15 Rev. 2 JCT

    The bus differential

    protection element

    picks upThe saturation

    flag is not set - no

    directional

    decision required

    The element

    operates in

    10ms

    The

    directional

    flag is set

    All the fault currents

    are seen in one

    direction

    CT Saturation Internal Fault Example

  • GE Digital Energy Multilin

    Page 72 2015-01-15 Rev. 2 JCT

    B30, B90 & B95Plus Application Considerations

  • GE Digital Energy Multilin

    Page 73 2015-01-15 Rev. 2 JCT

    B90 Applications for Large Busbars

    1 2 3 23 24

    ZONE 1

    Single Bus Single Breaker

    1 2 3 21 22

    ZONE 1

    ZONE 2

    23 24

    Double Bus Single Breaker

    B90-A

    B90-B

    B90-C

    B90-A

    B90-B

    B90-C

    B90-Logic

  • GE Digital Energy Multilin

    Page 74 2015-01-15 Rev. 2 JCT

    B90 Applications for Large Busbars Continued

    1 2 11

    ZONE 1

    12 13 22

    23 24ZONE 2

    Single Bus Single Breaker with Bus Tie

    1

    2

    3

    4

    21

    22

    23

    24

    ZONE 1

    ZONE 2

    Double Bus Double Breaker

    B90-A

    B90-B

    B90-C

    B90-A

    B90-B

    B90-C

  • GE Digital Energy Multilin

    Page 75 2015-01-15 Rev. 2 JCT

    Applying the B30 or B90 for Busbar Protection

    Basic Topics

    Configure physical CT Inputs

    Configure Bus Zone and Dynamic Bus Replica

    Calculating Bus Differential Element settings

    Advanced Topics

    Isolator Monitoring

    More on Dynamic Bus Replica Blind Spots & End Fault Protection

    Differential Zone CT Trouble

    Additional Security for the Bus Differential Zone

    B90 Application Example

  • GE Digital Energy Multilin

    Page 76 2015-01-15 Rev. 2 JCT

    Configuring CT Inputs

    For each connected CT circuit enter Primary rating and select Secondary rating.

    For the B30, each 3-phase bank of CT inputs must be assigned to a Signal Source (SRC1 through SRC6) which are then assigned to the

    Bus Zone and Dynamic Bus Replica

    For the B90, the CT channels are assigned directly to the Bus Zone and Dynamic Bus Replica (no Signal Sources)

    Both the B30 and B90 define 1 p.u. as the maximum primary current of all of the CTs connected in the given Bus Zone

  • GE Digital Energy Multilin

    Page 77 2015-01-15 Rev. 2 JCT

    B90 Per-Unit Current Definition - Example

    DSP Channel Primary Secondary Zone

    CT-1 F1 3200 A 1 A 1

    CT-2 F2 2400 A 5 A 1

    CT-3 F3 1200 A 1 A 1

    CT-4 F4 3200 A 1 A 2

    CT-5 F5 1200 A 5 A 2

    CT-6 F6 5000 A 5 A 2

    For Zone 1, 1 p.u. = 3200 Apri

    For Zone 2, 1 p.u. = 5000 A pri

  • GE Digital Energy Multilin

    Page 78 2015-01-15 Rev. 2 JCT

    Configuration of Bus Zone (Dynamic Bus Replica)

    Dynamic Bus Replica associates a status signal with each current in the Bus Differential Zone

    Status signal can be any FlexLogic operand

    Status signals can be developed in FlexLogic to provide additional checks or security as required

    Status signal can be set to ON if current is always in the bus zone or OFF if current is never in the bus zone

    For the B30, each Signal Source (SRC1 SRC6) must be assigned a status signal to be included in the three-phase Bus Zone

    For the B90, the CT channels are assigned status inputs directly in the respective Bus Zone(s) and the CT direction must also be

    configured for all current inputs in each bus zone

    In or Out, depending on CT polarity

  • GE Digital Energy Multilin

    Page 79 2015-01-15 Rev. 2 JCT

    differ

    ent

    ial

    restraining

    LOW

    SLOPE

    OPERATE

    BLOCK

    IR

    |ID|

    HIGH

    SLOPE

    LO

    W B

    PN

    T

    HIG

    H B

    PN

    T

    PICKUP

    Bus Differential Characteristic Settings

    6 key 87B settings to ensure correct differential characteristic for dependable and secure operation

  • GE Digital Energy Multilin

    Page 80 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings Pickup

    Pickup

    Defines the minimum differential current required for operation of the Bus Zone Differential element

    Must be set above maximum leakage current not zoned off in the bus differential zone (VTs for example)

    May also be set above maximum load conditions for added security in case of CT trouble, but better alternatives exist

    Range: 0.050 p.u. to 2.000 p.u. in 0.001 p.u. increments

  • GE Digital Energy Multilin

    Page 81 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings Low Slope

    Low Slope

    Defines the percent bias for the restraint currents from IREST=0 to IREST=Low Breakpoint

    Setting determines the sensitivity of the differential element for low-current internal faults

    Must be set above maximum error introduced by the CTs in their normal linear operating mode

    Range: 15% to 100% in 1%. increments

  • GE Digital Energy Multilin

    Page 82 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings Low Breakpoint

    Low Breakpoint

    Defines the upper limit to restraint currents that will be biased according to the Low Slope setting

    Should be set to be above maximum load but not more than maximum current where CTs still operate linearly (including residual flux)

    Assumption is that CTs will be operating linearly (no significant saturation up to 80% residual flux) up to the Low Breakpoint setting

    Range: 1.00 to 4.00 p.u. in 0.01 p.u. increments

  • GE Digital Energy Multilin

    Page 83 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings High Breakpoint

    High Break Point

    Defines the minimum restraint currents that will be biased according to the High Slope setting

    Should be set to be below the minimum current where the weakest CT will saturate with no residual flux

    Assumption is that CTs will be operating linearly (no significant saturation effects up to 80% residual flux) up to Low Breakpoint setting

    Range: 4.00 to 30.00 p.u. in 0.01 p.u. increments

  • GE Digital Energy Multilin

    Page 84 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings High Slope

    High Slope

    Defines the percent bias for restraint currents larger than high breakpoint

    Setting determines stability of differential element for high current external faults

    Should be high enough to tolerate spurious differential current during saturation of CTs on heavy external faults

    Setting can be relaxed in favor of sensitivity and speed as CT saturation and directional principle is used for security

    Range: 50% to 100% in 1% increments

  • GE Digital Energy Multilin

    Page 85 2015-01-15 Rev. 2 JCT

    Calculating Bus Differential Settings Unrestrained

    Unrestrained

    Defines the minimum differential current for unrestrained operation

    Should be set to be above the maximum differential current under worst case CT saturation

    Range: 2.00 to 99.99 p.u. in 0.01 p.u. increments

    Can be effectively disabled by setting to 99.99 p.u.

    Unrestrained Differential

  • GE Digital Energy Multilin

    Page 86 2015-01-15 Rev. 2 JCT

    Summing External Currents Not Recommended If additional circuit needed

    Relay becomes combination of restrained and unrestrained elements

    In order to parallel CTs:

    CT performance must be closely matched

    Any errors will appear as differential currents

    Associated feeders must be radial

    No backfeeds possible

    Pickup setting must be raised to accommodate any errors

    Rather change to B90 or B95Plus

    CT-1

    CT-2

    CT-3

    CT-4

    I 3 =

    0

    I 2 =

    0

    I 1 =

    Err

    or

    IDIFF

    = Error

    IREST

    = Error

    Maloperation if

    Error > PICKUP

  • GE Digital Energy Multilin

    Page 87 2015-01-15 Rev. 2 JCT

    Advanced Topics

  • GE Digital Energy Multilin

    Page 88 2015-01-15 Rev. 2 JCT

    Advanced Topics

    Isolators and Isolator Monitoring

    More on Dynamic Bus Replicas

    Blind Spots

    End Fault Protection

    Differential Zone CT Trouble

    Additional Security for the Bus Differential Zone

    External Check Zone

    Undervoltage Supervision

    Overcurrent Supervision

    B90 Application Examples

    B95Plus Application Examples

  • GE Digital Energy Multilin

    Page 89 2015-01-15 Rev. 2 JCT

    Isolators

    Reliable Isolator Closed signals are needed for the Dynamic Bus Replica

    In simple applications, a single normally closed contact may be sufficient

    For maximum security:

    Both N.O. and N.C. contacts should be used

    Isolator Alarm should be established and non-valid combinations (open-open, closed-closed) should be sorted out

    Switching operations should be inhibited until bus image is recognized with 100% accuracy

    Optionally block 87B operation from Isolator Alarm

    Each isolator position signal decides:

    Whether or not the associated current is to be included in the differential calculations

    Whether or not the associated breaker is to be tripped

  • GE Digital Energy Multilin

    Page 90 2015-01-15 Rev. 2 JCT

    Isolator Typical Open/Closed Connections

  • GE Digital Energy Multilin

    Page 91 2015-01-15 Rev. 2 JCT

    Full-Featured Isolator Monitoring

    Isolator Open Aux.

    Contact

    Isolator Closed Aux.

    Contact

    Isolator Position

    Isolator Alarm Block Switching

    Off On CLOSED No No

    Off Off LAST VALID After time delay until reset

    Until isolator position valid On On CLOSED

    On Off OPEN No No

    For the B30, this needs to be implemented using FlexLogic

    For the B90 & B95Plus, there are 48 dedicated Isolator Position monitoring elements

  • GE Digital Energy Multilin

    Page 92 2015-01-15 Rev. 2 JCT

    Switching An Isolator Closing Sequence

  • GE Digital Energy Multilin

    Page 93 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    TB Z1 Z2

    Bus Tie Breaker with Two CTs

    Overlapping zones no blind spots

    Both zones trip the Tie-Breaker

    No special treatment of the TB required in terms of its status for Dynamic Bus Replica (treat as regular breaker)

  • GE Digital Energy Multilin

    Page 94 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    Bus Tie Breaker with Single CTs

    TB Z1 Z2

    Both zones trip the Tie-Breaker

    Blind spot between the TB and the CT

    Fault between TB and CT is external to Z2

    Z1: no special treatment of the TB required (treat as regular CB)

    Z2: special treatment of the TB status required:

    The CT must be excluded from calculations after the TB is opened

    Z2 gets extended (opened entirely) onto the TB

  • GE Digital Energy Multilin

    Page 95 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    Sequence of events:

    1. Z1 trips and the TB gets opened

    2. After a time delay the current from the CT shall be removed

    from Z2 calculations

    3. As a result Z2 gets extended up to the opened TB

    4. The Fault becomes internal for Z2

    5. Z2 trips finally clearing the fault

    TB Z1 Z2

    expand

  • GE Digital Energy Multilin

    Page 96 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    CT

    CB

    Blind spot for

    bus protection

    Blind spot exists between the CB and CT

    CB is going to be tripped by line protection

    After the CB gets opened, the current shall be removed from differential calculations (expanding the differential zone up to the opened CB)

    Identical to the Single-CT Tie-Breaker

  • GE Digital Energy Multilin

    Page 97 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    CB

    CT

    Over-trip spot for bus protection

    Over-trip spot between the CB and CT when the CB is opened

    When the CB opens, the current shall be removed from differential calculations (contracting the differential zone up to the opened CB)

    Identical as for the Single-CT Tie-Breaker, but

    contra

    ct

  • GE Digital Energy Multilin

    Page 98 2015-01-15 Rev. 2 JCT

    Dynamic Bus Replica Changing the Bus Zone

    but

    A blind spot created by contracting the bus differential zone

    End Fault Protection required to trip remote end circuit breaker(s)

    CB

    CT

    Blind spot for

    bus protection

  • GE Digital Energy Multilin

    Page 99 2015-01-15 Rev. 2 JCT

    End Fault Protection (EFP)

    Instantaneous overcurrent element enabled when the associated CB is open to cover the blind spot between the CB and line-side CT

    Pickup delay should be long enough to ride-through the ramp down of current interruption (1.3 cycles maximum)

    EFP inhibited from circuit breaker manual close command

    For the B30, the End Fault Protections need to be implemented using FlexLogic

    For the B90 & B95Plus, there are 24 dedicated End Fault Protection elements

  • GE Digital Energy Multilin

    Page 100 2015-01-15 Rev. 2 JCT

    Differential Zone CT Trouble

    Each Bus Differential Zone (2 for the B30, 4 (6) for the B90 and B95Plus) has a dedicated CT Trouble Monitor

    Definite Time Delay overcurrent element operating on the zone differential current, based on the configured Dynamic Bus Replica

    Three strategies to deal with CT problems:

    1. Trip the bus zone as the problem with a CT will likely evolve into a bus fault anyway

    2. Do not trip the bus, raise an alarm and try to correct the problem manually

    3. Switch to setting group with 87B minimum pickup setting above the maximum load current.

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    Page 101 2015-01-15 Rev. 2 JCT

    Strategies 2 and 3 can be accomplished by: Using undervoltage supervision to ride through the period from the

    beginning of the problem with a CT until declaring a CT trouble condition

    Using an external check zone to supervise the 87B function

    Using CT Trouble to prevent the Bus Differential tripping (2)

    Using setting groups to increase the pickup value for the 87B function (3)

    DO NOT use the Bus Differential element BLOCK input: The element traces trajectory of the differential-restraining point for

    CT saturation detection and therefore must not be turned on and off

    dynamically

    Supervise the trip output operand of the 87B in FlexLogic instead

    Differential Zone CT Trouble

  • GE Digital Energy Multilin

    Page 102 2015-01-15 Rev. 2 JCT

    Differential Zone CT Trouble Strategy #2 Example

    CT Trouble operand is used to rise an alarm

    The 87B trip is inhibited after CT Trouble element operates

    The relay may misoperate if an external fault occurs after CT trouble but before the CT trouble condition is declared (double-contingency)

    87B operates

    Undervoltage condition

    CT OK

  • GE Digital Energy Multilin

    Page 103 2015-01-15 Rev. 2 JCT

    Additional Security for The Bus Differential Zone

    No matter how high the reliability, any relay may fail. For bus applications, any MTBF will never be high enough

    Consider securing the application against reasonable contingencies

    CT problems, AC wiring problem

    Problems with aux. switches for breakers, isolators

    DC wiring problems involving the Dynamic Bus Replica

    Failure of relay hardware (single current input channel, single digital input)

    Security above and beyond inherent security mechanisms in the B30/B90/B95Plus

    CT Saturation Detector

    Directional (Phase) Comparison

    Isolator monitoring

  • GE Digital Energy Multilin

    Page 104 2015-01-15 Rev. 2 JCT

    External Check Zone

    Principle:

    Develop an independent copy of the differential current for the entire bus regardless of dynamic zones for

    individual bus sections

    Use the check zone to supervise the tripping zone(-s)

    Use independent CTs / CT cores if possible to guard against CT and wiring problems

    Use independent relay current inputs to guard against relay problems

    Alarm on spurious differential

    Guards against:

    CT problems

    AC wiring problems

    Problems with aux switches for breakers and disconnectors

    DC wiring problems for dynamic bus replica

    Failures of current inputs

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    Page 105 2015-01-15 Rev. 2 JCT

    With only six 3-phase inputs the B30 handles up to 2 zones of protection

    Actual (tripping) zone shall be configured to reflect dynamic image of the bus

    External check zone can be configured in some circumstances as an unrestrained zone that (ideally) uses separate CTs or CT cores

    An IOC function may be configured if needed to operate on the externally summated currents (From different IED)

    For external zone identical CT ratios or matching transformers are required

    Make use of three ground CT inputs (IG) and Ground IOC or unused 3-phase bank & Phase IOC elements to provide check zone

    Application of the External Check Zone to the B30

  • GE Digital Energy Multilin

    Page 106 2015-01-15 Rev. 2 JCT

    87B phase A supervised by IOC1

    phase A; the IOC responds to the

    externally formed differential

    current

    Three-phase trip command

    Application of the External Check Zone to the B30

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    Page 107 2015-01-15 Rev. 2 JCT

    Application of the External Check Zone to the B90

    Version 1

    Use two different CTs / CT cores

    Place the supervising zone in a different chassis

    Strong security bias, practically a 2-out-of-2

    independent relay scheme

    Use fail-safe output to substitute for the permission

    if the supervising relay fails / is taken out of service

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)

    BUS DIF 4

    (SUPERVISING

    PHASE C)

    b c

    OR

    B90-A

    AN

    D

    TRIP A

    to B90-Cto B90-C

    from

    phase-C CT

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase B

    BUS DIF 1

    (TRIPPING

    PHASE B)

    BUS DIF 4

    (SUPERVISING

    PHASE A)

    b c

    OR

    B90-B

    AN

    D

    TRIP B

    to B90-C

    from B90-C

  • GE Digital Energy Multilin

    Page 108 2015-01-15 Rev. 2 JCT

    Application of the External Check Zone to the B90

    Version 2

    Use two different CTs / CT cores

    Place the supervising zone in the same chassis, different DSP module

    Strong security bias, almost 2-out-of-2 independent relay scheme

    Simpler panel wiring compared with version 1 (No inter chassis wiring needed)

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    b c

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)

    BUS DIF 4

    (SUPERVISING

    PHASE A)

    B90-A

    AND

    TR

    IP A

  • GE Digital Energy Multilin

    Page 109 2015-01-15 Rev. 2 JCT

    Application of the External Check Zone to the B90

    Version 3

    Use a single CT (simpler wiring)

    Place the supervising zone in a different chassis

    Guards against relay problems and bus replica

    problems

    Use fail-safe output to substitute for the permission

    if the supervising relay fails / is taken out of service

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)

    BUS DIF 4

    (SUPERVISING

    PHASE C)

    b c

    OR

    B90-A

    AN

    D

    TRIP A

    to B90-Cto B90-C

    from

    phase-C CT

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase B

    BUS DIF 1

    (TRIPPING

    PHASE B)

    BUS DIF 4

    (SUPERVISING

    PHASE A)

    b c

    OR

    B90-B

    AN

    D

    TRIP B

    from B90-C

    to B90-C

  • GE Digital Energy Multilin

    Page 110 2015-01-15 Rev. 2 JCT

    Application of the External Check Zone to the B90

    Version 4

    Use a single CT

    Place the supervising zone in the same chassis, different DSP module

    Guards against relay problems and bus replica problems

    No inter chassis wiring needed

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b ...

    DSP, SSot S

    S1c S1b S2c S2b S8c S8b

    b c

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)

    BUS DIF 4

    (SUPERVISING

    PHASE A)

    B90-A

    AND

    TR

    IP A

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    Undervoltage Supervision

    Principle:

    Supervise all differential trips with undervoltage

    Set high (0.85-0.90pu) for speed and sensitivity

    Need 3 UV elements per bus per phase (undervoltage functions AG, AB, CA

    supervise differential trip for phase A)

    Alarm on spurious differential

    Guards against:

    CT problems

    AC wiring problems

    Problems with aux switches for breakers and disconnectors

    DC wiring problems for dynamic bus replica

    Failures of current inputs

  • GE Digital Energy Multilin

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    Application of Undervoltage Supervision to the B90

    Version 1

    Place the supervising voltage inputs in a different chassis

    Guards against relay problems and bus replica problems

    Does not need any extra ac current wiring

    Use fail-safe output to substitute for the permission

    if the supervising relay fails / is taken out of service

    S7a S7cS6a S6c...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b

    DSP, SSot S

    ... S8a S8c

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)UV-1

    b c

    OR

    B90-A

    AN

    D

    TRIP A

    to B90-Cto B90-C

    ...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b

    DSP, SSot S

    B1a B2b

    Critifal Failure

    b ca b

    Digital Input

    a b

    Digital Input

    Phase B

    BUS DIF 1

    (TRIPPING

    PHASE B)O

    R

    AN

    D

    TRIP B

    from B90-C

    VCAVBCVCG

    UV-2 UV-3

    OR

    S7a S7cS6a S6c... S8a S8c

    UV-1

    b c

    VCAVABVAG

    UV-2

    OR

    B90-B

    UV-3

  • GE Digital Energy Multilin

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    Application of Undervoltage Supervision to the B90

    Version 2

    Place the supervising voltage inputs in the same chassis

    Guards against relay problems and bus replica problems

    Does not need any extra ac current wiring

    No inter chassis wiring needed

    S7a S7cS6a S6c...

    DSP, Slot F

    F1c F1b F2c F2b F8c F8b ...

    DSP, Slot L

    L1c L1b L2c L2b L8c L8b

    DSP, SSot S

    ... S8a S8c

    Phase A

    BUS DIF 1

    (TRIPPING

    PHASE A)UV-1

    VCAVABVAG

    UV-2 UV-3

    OR

    b c

    AND

    TR

    IP A

    B90-A

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    Overcurrent Supervision

    Principle:

    Supervise trips to breakers with OC condition set above maximum load

    Loads will not get tripped; facilitates bus transfer applications

    With a single CT / wiring / relay input problem, only up to one breaker will get tripped, not the entire bus

    Danger that very weak sources feeding a bus fault will not get tripped, solution possible via logic

    Guards against:

    CT problems

    AC wiring problems

    Problems with aux switches for breakers and disconnectors

    DC wiring problems for dynamic bus replica

    Failures of current inputs

    Typically, no trip will occur on CT and wiring problems

    A single CB may get tripped on specific relay problems (sees spuriously high current)

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    B90/B95Plus Application Examples

  • GE Digital Energy Multilin

    Page 116 2015-01-15 Rev. 2 JCT

    B90 Example Reconfigurable Bus

    Double bus, single breaker with bus-tie

    10 feeders with single CT

    Circuit breaker bypass switches per feeder CB

    Current inclusion in bus zone depends on isolator switch position (ISO x)

    CB1-2

    L8

    L7

    ISO

    1

    ISO

    2

    CB1

    F1IS

    O3

    CB2

    F2

    CB3

    F3

    CB4

    F4

    CB5

    F5

    CB6

    F6

    CB7

    F7

    CB8

    F8

    CB9

    L1

    CB10

    L2

    IOS

    4

    ISO

    5

    ISO

    6

    ISO

    7

    ISO

    8

    ISO

    9

    ISO

    10

    ISO

    11

    ISO

    12

    ISO

    13

    ISO

    14

    ISO

    15

    ISO

    16

    ISO

    17

    ISO

    18

    ISO

    19

    ISO

    20

    ISO

    21

    ISO

    22

    ISO

    23

    ISO

    24

    ISO

    25

    ISO

    26

    ISO

    27

    ISO

    28

    ISO

    29

    ISO

    30

    ISO

    31

    ISO

    32

    ZONE 1=BUS1

    ZONE 2=BUS2

    ZONE 3=CHECK ZONE

  • GE Digital Energy Multilin

    Page 117 2015-01-15 Rev. 2 JCT

    B90 Example Architecture

    Breaker Failure

    inputs and outputs

    Phase A AC signals

    and trip contacts

    Phase B AC signals and trip contacts

    Phase C AC signals

    and trip contacts

    Digital Inputs for

    isolators and

    breakers monitoring

    Tx Rx

    Rx Tx

    Dir

    ect

    I/O

    Rin

    g (C

    h. 1

    ) Direct I/O

    Rin

    g (C

    h. 2

    )

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    INCLUSION OF FEEDER CTs INTO BUS 1(ZONE 1), OR BUS 2(ZONE 2) PROTECTION

    B90 Example Dynamic Bus Replica Logic

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    DIFFERENTIAL ZONE 2 (BUS 2)

    Differential current: Id = F2 + F4 + F5 +F6 +F7 +L1 + L7

    Restraint current: Ir = max(F2, F4, F5, F6, F7, L1, L7)

    DIFFERENTIAL ZONE 3 (CHECK ZONE = BUS 1 + BUS 2)

    Differential current: Id = F1 +F2 + F3 +F4 +F5 +F6 +F7 + F8 + L1 +L2 +

    + (L7 OR L8) WHEN FEEDER CT BY-PASSED

    Restraint current: Ir = max(F1, F2, F3, F4, F5, F6, F7, F8, L1, L2,

    (L7 OR L8) WHEN FEEDER CT BY-PASSED)

    DIFFERENTIAL ZONE 1 (BUS 1)

    Differential current: Id = F1 + F3 + F8 + L2 + L8

    Restraint current: Ir = max(F1, F3, F8, L2, L8)

    B90 Bus Zone Definitions (Dynamic Bus Replica)

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    B90-1 A PHASE

    B90-2 B PHASE

    B90-3 C PHASE

    B90-5 BKR FAIL

    B90-4 STATUS

    Direct outputs on IED4

    Direct inputs on IED1, 2, and 3

    Fiber Optic

    channels

    Differential zones

    configuration on

    IED1, 2, and 3

    ZONE 1 ZONE 2 ZONE 3

    B90 Direct I/O Communications Configuration

    Isolators and breakers

    positions

  • GE Digital Energy Multilin

    Page 121 2015-01-15 Rev. 2 JCT

    B90 Example AG Fault on Bus 1

    CB1-2

    L8

    L7

    ISO

    1

    ISO

    2

    CB1

    F1IS

    O3

    CB2

    F2

    CB3

    F3

    CB4

    F4

    CB5

    F5

    CB6

    F6

    CB7

    F7

    CB8

    F8

    CB9

    L1

    CB10

    L2

    IOS

    4

    ISO

    5

    ISO

    6

    ISO

    7

    ISO

    8

    ISO

    9

    ISO

    10

    ISO

    11

    ISO

    12

    ISO

    13

    ISO

    14

    ISO

    15

    ISO

    16

    ISO

    17

    ISO

    18

    ISO

    19

    ISO

    20

    ISO

    21

    ISO

    22

    ISO

    23

    ISO

    24

    ISO

    25

    ISO

    26

    ISO

    27

    ISO

    28

    ISO

    29

    ISO

    30

    ISO

    31

    ISO

    32

    ZONE 1=BUS1

    ZONE 2=BUS2

    ZONE 3=CHECK ZONE

  • GE Digital Energy Multilin

    Page 122 2015-01-15 Rev. 2 JCT

    B90 Example AG Fault on Bus 1 Trip with BF Logic

    AG Undervoltage

    AB Undervoltage

    CA Undervoltage

    BUS1 OP

    BUS3 BIASED PKP

    Trip 87B Zone1

    BF Trip Zone1

    80msTIMER

    Trip Zone1 87B or BF

    AG Undervoltage

    AG Undervoltage

    AG Undervoltage

    BUS2 OP

    BUS3 BIASED PKP

    Trip 87B Zone2

    BF Trip Zone2

    80msTIMER

    Trip Zone2 87B or BF

    *

    *

    * Denotes a binary signal received from an external B90 via communications (Direct I/O,

    GOOSE/GSSE)

  • GE Digital Energy Multilin

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    B90 Example AG Fault on Bus 1 Trip Logic

    Trip Zone1 87B or BF

    Trip Zone2 87B or BF

    ISO 31 ON

    ISO32 ON

    TRIP CB1-2

    F1 in Zone1

    TRIP CB1F1 in Zone2

    F2 in Zone1

    TRIP CB2F2 in Zone2

    F3 in Zone1

    TRIP CB3F3 in Zone2

    F4 in Zone1

    TRIP CB4F4 in Zone2

    F5 in Zone1

    TRIP CB5F5 in Zone2

    F6 in Zone1

    TRIP CB6F6 in Zone2

    F7 in Zone1

    TRIP CB7F7 in Zone2

    F8 in Zone1

    TRIP CB8F8 in Zone2

    L1 in Zone1

    TRIP CB9L1 in Zone2

    L2 in Zone1

    TRIP CB10L2 in Zone2

    *

    *

    *

    *

    *

    *

    *

    *

    *

    *

    *

    * *

    *

    *

    *

    *

    *

    *

    *

    *

    *

  • GE Digital Energy Multilin

    Page 124 2015-01-15 Rev. 2 JCT

    B95Plus Large Double Bus

    Two Double Buses tied together

    20 Feeders

    4 Bus Couplers

    Requirements:

    Differential Protection

    Isolator Position Monitoring

    Supervision for Isolator position monitoring failure

  • GE Digital Energy Multilin

    Page 125 2015-01-15 Rev. 2 JCT

    One Solution: (1) B95Plus

    B32 B31 B27 B25 B23 B21

    B28 B26 B24 B22

    B20

    B19

    B20

    B12

    B10

    B8

    B6

    B4

    B2

    B3

    B5

    B7

    B9

    B19

    One Solution

    v One B95Plus

    v 14 Bricks (10 shared between feeders, 4 for bus couplers)

    v 4 bus zonesv Check zone possible

  • GE Digital Energy Multilin

    Page 126 2015-01-15 Rev. 2 JCT

    B95Plus Shared Brick

    3 currents

    B28 B26

    3 currents

    2 status2 control

    2 status2 control

    2 status2 status

    Brick wired for both circuits

    v Source currents (3)v Breaker control (2 outputs)v Breaker status (2 inputs)v Isolator status (2 inputs each)

    One circuit

  • GE Digital Energy Multilin

    Page 127 2015-01-15 Rev. 2 JCT

    Better solution: (2) B95Plus Systems

    B32 B31 B27 B25 B23 B21

    B28 B26 B24 B22

    B20

    B19

    B20

    B12

    B10

    B8

    B6

    B4

    B2

    B3

    B5

    B7

    B9

    B19

    Better Solution

    v Two B95Plus

    v 24 Bricks v 2 bus zones per B95Plus

    v Check zone not possible

  • GE Digital Energy Multilin

    Page 128 2015-01-15 Rev. 2 JCT

    Breaker-and-a-half

  • GE Digital Energy Multilin

    Page 129 2015-01-15 Rev. 2 JCT

    Conclusions

  • GE Digital Energy Multilin

    Page 130 2015-01-15 Rev. 2 JCT

    Conclusions

    B30

    For smaller busbars (up to 6 feeders, 2 Zones)

    Single chassis providing three-phase bus differential protection, logic and I/O capabilities

    Isolator monitoring may be done in FlexLogic if required

    End Fault Protection may be provided using FlexLogic if required

    Additional security can be provided (fewer feeders in zone)

    Inter-relay communications supported for additional I/O

    B90 and B95Plus

    For large, complex busbars (up to 24 feeders, 6 Zones)

    (B90)Multiple chassis for single-phase bus differential, plus extra IEDs for dynamic bus replica, breaker fail

    Internal full-feature isolator monitoring provided

    24 End Fault Protection elements provided (B90 and B95Plus)

    Additional security can be provided (fewer feeders in zone)

    Inter-relay communications supported for additional I/O

  • GE Digital Energy Multilin

    Page 131 2015-01-15 Rev. 2 JCT

    Conclusions

    B30 is limited in scope to small busbars, therefore application is fairly simple and straightforward

    B90 designed to be applied to large complex busbars, therefore application can be quite complicated:

    Multiple B90s:

    Protection Algorithm processing

    Dynamic Bus Replica logic

    Isolator monitoring

    Breaker Failure

    Inter-relay Communication schemes for I/O transfer, inter-tripping

    GE Multilin can provide a complete engineered B90 System Solution, based on specific customer application & requirements

  • GE Digital Energy Multilin

    Page 132 2015-01-15 Rev. 2 JCT

    Conclusions

    B30, B90 and B95Plus provide secure, high performance bus differential protection for reconfigurable busbars using the same

    proven algorithms

    Both B30 and B90 are members of the Universal Relay (UR) family, with common configuration and management tools for all relays:

    EnerVista UR Setup: Universal configuration tool

    EnerVista ViewPoint: software suite for all GE Multilin IEDs

    Launchpad: Device Setup & Document Management

    Engineer: Advanced Logic Design & Monitoring (Optional)

    Maintenance: Troubleshooting & Reporting Tools (Optional)

    Monitoring: Monitoring & Data Recording for Small Systems (Optional)

    www.GEMultilin.com

  • GE Digital Energy Multilin

    Page 133 2015-01-15 Rev. 2 JCT

    Conclusion: B95Plus as Centralized DFR

    DFR functionality includes an Event Recorder and Transient Recorder

    Event Recorder

    8,192 events on Main Card

    8,192 events on each process card

    Events viewable on HMI window or retrievable through setup software

    Transient Recorder

    Up to 50 records, up to 128 samples / cycle

    Re-trigger capability to extend recording as additional triggers are asserted

    128 digital channels and triggers for Main card, each process card

    Captures all bus source currents, voltage sources, differential and restraint currents

    All data reviewable through EnerVista B95Plus Setup Software

  • GE Digital Energy Multilin

    Page 134 2015-01-15 Rev. 2 JCT

    Q & A