New Techniques for the Monitoring of Transformer Techniques for the Monitoring of Transformer Condition. Agenda ... • On-line monitoring as future trend • C/DF monitoring –The reference problem

  • Published on
    17-Mar-2018

  • View
    214

  • Download
    2

Transcript

  • Thomas Prevost OMICRON electronics USA

    IEEE T&D Conference

    Chicago, Illinois April 17, 2014

    New Techniques for the Monitoring of

    Transformer Condition

  • Agenda

    Monitoring Expectations & Needs

    Bushing Monitoring

    Capacitance

    Power Factor

    Transformer Monitoring

    Partial Discharge

    Voltage Transients

    Summary & Conclusions

  • Scope of Monitoring Expectations and Needs

    Continuous Diagnostics

    Condition based maintenance

    Full utilization of life span

    Fa

    ilure

    Ra

    te

    time / a 0 10 20

    Classical

    Diagnostics

    Temporary

    Monitoring

    Permanent

    Monitoring

    5a

    3a

  • Scope of Monitoring Expectations and Needs

    Arguments and user expectations

    > Continuous monitoring under service conditions

    Reliable measurement data

    > Diagnostic of errors before they appear

    Condition based maintenance

    > Knowledge about historical use

    Fully utilize life span of equipment

  • Transformer Failure Statistics

    [Viereck, Hillinger, Transform 2011]

  • Agenda

    Monitoring Expectations & Needs

    Bushing Monitoring

    Capacitance

    Power Factor

    Transformer Monitoring

    Partial Discharge

    Voltage Transients

    Summary & Conclusions

  • According to the data from various researches and

    electric power utilities, bushings failures make 5 to

    50 %, or in average, one quarter of the total

    number of transformer failures .These failures most

    commonly cause transformer fires which may result

    in huge collateral damages of switchyard.

    Reference [3] indicates that 30 % of generator

    step-up transformer failures are caused by a

    bushing malfunction, and that they also cause

    56 % of failures accompanied by fire.

  • Failure Mechanisms and Diagnostics

    Partial breakdowns

    Capacitance

    Partial discharges

    Voltage

    [kV]

    No. of

    layers

    %

    change

    123 14 7.1

    245 30 3.3

    420 40 2.5

    550 55 1.8

    A

    Emax= high

    Emax= low

    A

    without

    layers

    with layers

  • Failure Mechanisms and Diagnostics

    Voids, cracks

    Partial discharges

    Capacitance

    Ageing by-products, moisture

    Dissipation factor / power factor

    0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    Dis

    sip

    atio

    n F

    acto

    r (%

    )

    typ: 0,25

    OIP

    typ: 0,35

    IEC60137 max: 0,7 %

    RIP 0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    Po

    wer

    Fac

    tor

    (%)

    typ: 0,25

    OIP

    typ: 0,35

    max: 0,85

    RIP

    max: 0,5

    IEEE C57.19.01

  • Where Can I Get the Reference from?

    Off-line test: Reference from HQ capacitor

    On-line test: Reference?

    u

    U X (t) U R (t) Z 1

    Z 2

    C X, C R

    0 (t)

    Reference Measurement path

    I R I X

    Im

    j

    d

    Uo

    IX IR

  • Relative C/DF Measurement

    > Sum of the bushing currents

    > Three phase vectors are added up

    > Bushing-to-bushing comparison

    > Vectors of bushings in same phase are

    compared

    L1

    L2 L3

  • from 2011-02-13 to 2011-02-15

    [P. Picher Integration of New Transformer Monitoring Technologies ...

    TechCon Asia-Pazific 2011]

    Systematic error

    0.65 %

    plus instrument

    inaccuracy 0.5 %

    Capacitance?

    DF impossible!

    0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    DF

    (%)

    typ: 0,25

    OIP

    typ: 0,35

    Systematic error

    RIP

    PAGE 12

  • VT Bushing

    Data Storage and

    Analysis Unit

    Connection Diagram VT Reference

    j

    d

    IB UVT+

    90

  • TanDelta Measurement Phase U

    Comparison to accurate

    off-line tests:

    DF 2.701 E-3

    C (pF) 467.1

  • C/DF Measurement over 1.75 Years

    0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    DF

    (%)

    typ: 0,25

    OIP RIP

    400

    467 +/- 2 pF Measurement

    478 pF Warning

    500

    Cap

    acit

    ance

    (p

    F)

    0,27 +/- 0,05 % Measurement

    0.7 % IEC Warning

  • DF Temperature Correction

    [ABB Guide for Bushing diagnostics and conditioning, Ludvika 2000]

  • Agenda

    Monitoring Expectations & Needs

    Bushing Monitoring

    Capacitance

    Power Factor

    Transformer Monitoring

    Partial Discharge

    Voltage Transients

    Summary & Conclusions

  • Reasons and Effects of Partial Discharges

    Reasons

    Failures of design or during manufacturing process

    Aging of equipment

    Electrical stress

    Thermal stress

    Mechanical stress

    Effects of PDs:

    Heating

    Creeping destruction of the insulation material

    Treeing, chain reaction

    Insulation breakdown, short circuit

    Treeing in polyethylene

  • PD Activity

    over 4 Days

    10

    1

    0.1

    0.01

    00:00:00 01:00:00 02:00:00 03:00:00 04:00:00 05:00:00

    Q in

    nC

    t in dd:hh:min

    L1L2L3

  • Fighting PD Noise: UHF Gating

    Electr. PD

    UHF PD

    Internal

    PD

    Corona

    EM Field

  • Combination of the Methods

    IEC PD Measurement

    Corrected IEC PD Measurement

    & UHF PD Measurement

    IEC

    UHF

  • 3PARD: PD Discrimination by Amplitude

    MPD1

    Internal

    PD

    Corona

    EM Field

    MPD2 MPD3

    1

    2 3

  • 3PARD and Back Transformation

  • 3FREQ: PD Discrimination by Spectrum

    MPD1

    Internal

    PD

    Corona

    EM Field

    0.5M

    2M 8M

    f

    A

    0.5M 2M 8M

  • PD Risk Assessment

    Noise rejection

    Source separation

    Pattern classification

    PD localization

    Galvanic

    decoupling

    Gating

    UHF

    RTD

    3 PARD

    3 FREQ

    Manual

    Automatic

    Asset

    Phase

    Acoustic

    localization

  • Agenda

    Monitoring Expectations & Needs

    Bushing Monitoring

    Capacitance

    Power Factor

    Transformer Monitoring

    Partial Discharge

    Voltage Transients

    Summary & Conclusions

  • Switching Transients

    Dr. Robert Degenneff

    IEEE PES Transformers

    Committee

    Tutorial March 2014

  • Switching Transients

    0

    Vo

    lta

    ge

    in

    kV

    t in ms 80 40 0

    200

    -200

    24 17 t in ms

    0

    Vo

    lta

    ge

    in

    kV

    t in ms 100 50 0

    200

    -200

    29 15 t in ms

  • G

    Grid400 kV

    GSU1100 MVA

    Generator900 MW

    21 kVTransmission line

    400 kV6 km

    Substation

    Transformer 2Transformer 1

    ca. 10 m

    UMTS

    Generator

    OMS843- PD- Transients- C/DF

    UHF620 + UVS

    OMS843- PD- Transients- C/DF

    Voltag Transformers

    OMS843- C/DF

    (Reference)

    UHF620 + UVS

    PDM600

    Case Study: Combined Generator and

    Transformer Monitoring

  • C/DF and PD Couplers

    Generator:

    Capacitive couplers

    Transformer:

    Capacitive bushing

    adapters and UHF

    drain valve sensor

  • Transformer 2Transformer 1

    ca. 10 m

    UMTS

    Generator

    OMS843- PD- Transients- C/DF

    UHF620 + UVS

    OMS843- PD- Transients- C/DF

    Voltage Transformers

    OMS843- C/DF

    (Reference)

    UHF620 + UVS

    PDM600

    Monitoring Results

    20 10 0 t in ms

    1

    0.1

    0.01

    QIE

    C in

    nC

    10

    20 10 0 t in ms

    100

    1

    0.001

    U in

    V

    1000 500 0 f in MHz

    P in d

    Bm

    -120

    -100

    -60

    0,0%

    0,2%

    0,4%

    0,6%

    0,8%

    1,0%

    11-20-2012 11-25-2012 11-30-2012

    DF

    / %

    U

    V

    W

  • Influence of Environmental Conditions

    0 5 10 15 0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    0.9

    1 d

    issip

    ation

    fa

    cto

    r in

    %

    0

    5

    10

    15

    20

    25

    30

    35

    40

    tem

    pe

    ratu

    re in

    C

    V-phase

    U-phase W-phase

    IEC60137 max: 0,7 %

    time / days

  • G

    Grid400 kV

    GSU1100 MVA

    Generator900 MW

    21 kVTransmission line

    400 kV6 km

    Substation

    0

    Vo

    lta

    ge

    in

    kV

    18 t in ms 12 6 0

    200

    -400

    400

    -200

    C Phase

    B Phase

    A Phase

    BAT20

    BAT10

    0

    Vo

    lta

    ge

    in

    kV

    200

    -400

    400

    -200

    Transient Over-Voltages

    > Oszillation frequency 10 kHz,

    beat frequency 600 Hz

    > Several times a day

    t in ms 12 6 0

    BAT10

    18 t in ms 12 6 0

  • Agenda

    Monitoring Expectations & Needs

    Bushing Monitoring

    Capacitance

    Power Factor

    Transformer Monitoring

    Partial Discharge

    Voltage Transients

    Summary & Conclusions

  • Summary

    On-line monitoring as

    future trend

    C/DF monitoring

    The reference problem

    Solution: VT reference

    Accuracy +/- 2pF

    On-line PD monitoring

    The noise problem

    Possible solutions:

    UHF-gating

    Software separation

    Pattern recognition

    Voltage Transients

  • Questions??

    Thomas Prevost

    thomas.prevost@omicronusa.com

Recommended

View more >