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Developments in Diagnosis of High Voltage Apparatus Michael Muhr Univ.-Prof. Dipl.-Ing. Dr.techn. Dr.h.c. Institute of High Voltage Engineering and System.

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Presentation on theme: "Developments in Diagnosis of High Voltage Apparatus Michael Muhr Univ.-Prof. Dipl.-Ing. Dr.techn. Dr.h.c. Institute of High Voltage Engineering and System."— Presentation transcript:

1 Developments in Diagnosis of High Voltage Apparatus Michael Muhr Univ.-Prof. Dipl.-Ing. Dr.techn. Dr.h.c. Institute of High Voltage Engineering and System Management University of Technology Graz

2 Institute of High Voltage Engineering and System Management M. Muhr Monitoring Recording of technical or characteristic values Evaluation of these values Recognition of the condition and proposal for problem-solving strategies Analysis Diagnosis

3 Institute of High Voltage Engineering and System Management M. Muhr Technical Diagnostics - TD - Science of recognition of the condition of technical systems - Aim of TD is to identify, to check and to classify characteristics of the condition of technical systems  to change or to influence the condition of these systems - Quality assurance of technical systems - Avoidance of an outage of technical systems

4 Institute of High Voltage Engineering and System Management M. Muhr Technical Diagnostic + Prevent failure + Increase reliability + Economic use of equipment Optimized usage of diagnostic tools Technique / method Time interval Complexity - Costs - Effort - System

5 Institute of High Voltage Engineering and System Management M. Muhr Availability of technical systems Condition evaluation Risk evaluation Technical Diagnostics Maintenance Repair Modernization

6 Institute of High Voltage Engineering and System Management M. Muhr Life Cycle Lifetime Condition „normal“defect critical threshold load pollution ageing tt „lifetime extention" by maintenance failure

7 Institute of High Voltage Engineering and System Management M. Muhr Stress and Ageing Models

8 Institute of High Voltage Engineering and System Management M. Muhr Lifetime Estimation of Transformers

9 Institute of High Voltage Engineering and System Management M. Muhr Technical Diagnostic Evaluation

10 Institute of High Voltage Engineering and System Management M. Muhr Aim of TD Current condition Modernization Original condition - Monitoring - Analysis - Diagnosis - Preventive maintenance - Repair Original condition with ageing - Ageing behaviour - Life time

11 Institute of High Voltage Engineering and System Management M. Muhr Tasks of TD Decision - Continuation of operation - Maintenance - Renewing Monitoring of equipment Investigations at equipment and models Life-time behaviour Characteristic values, current, voltage etc. Determining of limitsSetting of continuous voltage strength Optimization of life-time

12 Institute of High Voltage Engineering and System Management M. Muhr Bathtub Curve: from statistical analysis  <1: early failure  =1: stochastic process  >1: ageing process Weibull Distribution: Determination of Early Failures

13 Institute of High Voltage Engineering and System Management M. Muhr Ageing of an electrical insulation system Ageing mechanism Instrinic Exstrinic Single stress Multi stress Electrical insulation system Failure Ageing stress Thermal Electrical Ambient Mechanical

14 Institute of High Voltage Engineering and System Management M. Muhr TD at equipment of electrical power engineering Partial discharge diagnostic U e Q (pd) φ (pd) Thermal diagnostic Thermovision Temperature measurement Mechanical diagnostic Sound emission analysis Dilatometry Mechanical spectrometry Analysis of mechanical quantities Dielectric diagnostic U e u(t) C(f) tan δ(f) Analytic and spectrometry UV, VIS, IR - Spectrometry Gaschromatography Mass spectrometry Visual diagnostic UV - Videography Thermography Endoscopy X-ray graphy Breakdown diagnostic U d φ (U d ) t (U d )

15 Institute of High Voltage Engineering and System Management M. Muhr Maintenance Strategies - Lifetime

16 Institute of High Voltage Engineering and System Management M. Muhr Blockdiagramm of a Diagnosis System Reference components Excitation Measuring voltage Measuring temperature Control Voltage Temperature Assessment and control unit Storage of quantities Run-off control Data processing Input and Presentation Further processing Interface Diagnosis sample Original Mode Data acquisition - Sensors Stress generation Voltage Temperature Vibrations Climate

17 Institute of High Voltage Engineering and System Management M. Muhr Non – Destructive TD at Power Apparatus Power apparatus Cables Solid switchgears Capacities Transformers Instrument- transformers Rotating machines Insulators Conventional switchgears Circuit breaker Gasinsulated switchgears Dielectric diagnostic Visual TD Pd-diagnostic Sound emission diagnostic Dielectric diagnostic Visual TD Pd-diagnostic Sound emission diagnostic Gas analysis Dielectric diagnostic Visual TD Pd-diagnostic Sound emission diagnostic TD of mechanical quantities Dielectric diagnostic Visual TD Pd-diagnostic Sound emission diagnostic Leakage current diagnostic Visual TD TD of thermal and mechanical quantities Pd-diagnostic Leakage current diagnostic Visual TD TD of thermal quantities Sound emission diagnostic Pd-diagnostic

18 Institute of High Voltage Engineering and System Management M. Muhr Basis Aspects of TD - Aim - Technique - Method - Quantity - Connection between quantity and physical / chemical / technical structure of diagnostic sample - Diagnostic criterion - limit

19 Institute of High Voltage Engineering and System Management M. Muhr Technical Diagnostic Thermal Mechanical Dielectrical Partial Discharge Breakdown Material analytic and Spectrometry Meaningfulness (stress) Non-destructive individual testing Quasi non-destructive Partly individual testing Destructive Type approval test Random check

20 Institute of High Voltage Engineering and System Management M. Muhr Electrical Diagnostic Methods Partial Discharge Breakdown Dielectric

21 Institute of High Voltage Engineering and System Management M. Muhr Insulation Resistance Capacity and Dissipation Factor Isothermal Relaxation Current Analysis (IRC) Polarisation / Depolarisation Current Analysis (PDC) Frequency Response Analysis (FRA) Observation and evaluation of interaction of electric fields and material Dielectric Diagnostics

22 Institute of High Voltage Engineering and System Management M. Muhr U=U= I RSRS RORO RDRD U=U= I RSRS RORO RDRD Insulations Resistance Surface Resistance Insulation Resistance Guard Ring Arrangement

23 Institute of High Voltage Engineering and System Management M. Muhr Capacity and Dissipation Factor CXCX RXRX CNCN PC DSP A D A D CXCX RXRX CNCN R3R3 R4R4 CNCN HV

24 Institute of High Voltage Engineering and System Management M. Muhr Analyse in Time Domain VAA Discharge Voltage AnalyseDischarge Current AnalyseRecovery Voltage AnalyseCharging current Analyse 0% 20% 40% 60% 80% 100% 120% PDC IRC PDC RVM current voltage Schema

25 Institute of High Voltage Engineering and System Management M. Muhr Isothermal Relaxation Current Analysis (IRC) VAA Schema

26 Institute of High Voltage Engineering and System Management M. Muhr Polarisation / Depolarisation Current Analysis (PDC) VAA Polarisation Depolarisation Time Schema

27 Institute of High Voltage Engineering and System Management M. Muhr Frequency Response Analysis (FRA) U, I HVLV

28 Institute of High Voltage Engineering and System Management M. Muhr Breakdown Diagnostic HV-AC

29 Institute of High Voltage Engineering and System Management M. Muhr Breakdown Test with Insulating Oil

30 Institute of High Voltage Engineering and System Management M. Muhr Partial Discharge (PD) Measurement Sensitive nondestructive method as important diagnostic tool for evaluation of the insulation condition PD-defect Location and Detection Electrical Non electrical methods

31 Institute of High Voltage Engineering and System Management M. Muhr Partial Discharge Diagnostic Optical Electrical Mechanical Chemical IEC HF/VHF/UHF Acoustic Opto-acoustic HV

32 Institute of High Voltage Engineering and System Management M. Muhr Conventional electrical measurement Integration at frequency domain Narrow-band Wide-band Integration at time domain G Z Filter HV-Source Test object Coupling capacitor PD-System HV measure PD Pulse Quadripole Measuring impedance PD-Detection Methods IEC 60270

33 Institute of High Voltage Engineering and System Management M. Muhr PD-Measurement Results Phase correlated Single impulses Time correlated

34 Institute of High Voltage Engineering and System Management M. Muhr PDC Analyse

35 Institute of High Voltage Engineering and System Management M. Muhr Unconventional PD-Detection Surface Fibre in oil/board LWL fibre

36 Institute of High Voltage Engineering and System Management M. Muhr PD-Detection Methods Electrical measurements with high frequencies - HF / VHF method – 3 MHz to 300 MHz - UHF method – 300 MHz to 3 GHz Acoustic measurements – 10 kHz to 300 kHz Optical measurements – ultraviolet – visible – infrared range Chemical measurements - Optical - Chemical Directional microphone PD HV - Acoustic

37 Institute of High Voltage Engineering and System Management M. Muhr HF / VHF – PD-Measurement measurement impedance cable HV source PD-signal inductive galvanic PD-signal current wire sheath cable PD-signal Rogowski coil PD-signal sheath interruption measurement impedance cable

38 Institute of High Voltage Engineering and System Management M. Muhr Rogowski coil PD Analyser Measuring for HF – PD-detection on machines, VHF – PD-coupler, Split ring Rogowski coil Rogowski coil HF / VHF – PD-Measurement

39 Institute of High Voltage Engineering and System Management M. Muhr Principle of the coupler sensor HF / VHF – PD-Measurement direct. coupling A B direct. coupling C D impulse source / - No. signal at coupling output ABCD joint /1–XX– left cable / 2X–X– right cable / 3–X–X

40 Institute of High Voltage Engineering and System Management M. Muhr low-pass filter Peak detector PD measuring instrument PRPD pattern Wide bandNarrow band Spectrum analyser amplifiers UHF – PD-measurement UHF – PD-Measurement

41 Institute of High Voltage Engineering and System Management M. Muhr - Mobile UHF-window sensor - Conventional UHF-sensors Disc sensor Cone sensor Conductor Cage Dectector Field grading electrodes UHF – PD-Sensors Conductor Cage Detector

42 Institute of High Voltage Engineering and System Management M. Muhr L1 Schematic arrangement Sensor 1 Pre amplifier Measuring instrument L2 Sensor Sensor Sensor 2 Time delay Zeit Amplitude 1 2 UHF – PD-Fault Location Defect

43 Institute of High Voltage Engineering and System Management M. Muhr SF 6 Air Box AE Sensor Acoustic – PD-Measurement Acoustic Partial Discharge Detection Acoustic signal as a result of the pressure wave produced by PD Frequency spectrum 10 Hz up to 300 kHz Principle schematic to the acoustic PD-detection

44 Institute of High Voltage Engineering and System Management M. Muhr Acoustic – PD-Sensors HV Time delay Sensor PD Time Signal Directional microphone PD HV - Piezo-electric (sound emission) - Condenser microphones - Structure-born sound-resonance - Accelerometer - Opto-acoustic-sensor

45 Institute of High Voltage Engineering and System Management M. Muhr amplifier Oscilloscope AE Sensor PD-Detector Filter A/D Converter Acoustic – PD-detection system Acoustic – PD-Measurement

46 Institute of High Voltage Engineering and System Management M. Muhr Experimental setup of the optical interferometric detection of PD Opto-Acoustic – PD-Measurement Laser Reference optical fibre coil Sensing optical fibre coil Oil tank High Voltage PD-source Detector Beam Splitter Beam Splitter

47 Institute of High Voltage Engineering and System Management M. Muhr Measuring circuit after IEC and optical measuring system Optical fibre with lens Optical fibre Lens Peak Medium oil Observation area Fluorescent optical fibre conventional opt. fibre Peak fluorescent opt. fibre Plate PD – Optical Detection Rd PC LWL M ST CC VP PR W IEC 270 optical system Oscilloscope, ADU Signal- conversion Voltage supply

48 Institute of High Voltage Engineering and System Management M. Muhr Emission spectrum of corona discharges in SF 6 Test arrangement for optical PD-measurement SF 6 Photomultiplier Conv. PD Detector ADU I/U Oscilloscope Optical – PD-Detection in GIS

49 Institute of High Voltage Engineering and System Management M. Muhr Operation diagram camera DayCor II TM and application Optical – PD-Measurement

50 Institute of High Voltage Engineering and System Management M. Muhr PD – Application UHF - GIS - GIL - Transformer monitoring HF / VHF - High voltage cables - Transformers Acoustic - High voltage cables - GIS - Transformers - Overhead lines Optical - GIS - Overhead lines Chemical - GIS - Transformer - Machines Electrical -Transformers - GIS - Machines - GIS - Overhead lines -...

51 Institute of High Voltage Engineering and System Management M. Muhr Data input and monitoring unit ReportDisplayData archiving Real time announcement AlarmData transferTrend analysis Modem Telephone lines PC station Monitoring, Data Processing, Announcement

52 Institute of High Voltage Engineering and System Management M. Muhr Signal processing ReportDisplayData storeData transferTrend analysis Example for signal processing Pattern Recognition

53 Institute of High Voltage Engineering and System Management M. Muhr PD-Evaluation Loss Factor Insulation Resistance FRA-Analysis PD Location Partial Discharges Insulation Signal Analysis Transfer Function Wavelet Technique RVM, FDS Analysis Endoscopy Dynamics Oil Stream Transient Oil Pressure UHF PD-Detection Operating Noises Acoustics Oil Analysis Moisture Furane Values IEC 599 IEEE C Dörnenburg Rogers Duval Other Methods Dissolved Gas Analyses (DGA) Neutralization Value Elektrisch Mechanisch Thermisch Electrical Optical Mechanical Chemical Thermal Thermography Temperature Monitoring Operating Temperature Eye PDC-Analysis Fibre Optics Loss Factor Breakdown Voltage Oil Analysis DAC-PD-Measurement Power Transformer Diagnostics

54 Institute of High Voltage Engineering and System Management M. Muhr MethodInformationComment Oil analysisOAOil ageing, insulation propertyRoutine Gas-in-oil analysisDGA Oil and paper ageing, flashovers, PD, hot spots Routine Loss factor (Dielectric dissipation factor) tanδDielectric losses in the insulation systemRoutine Furane valuesFAAgeing of the paper insulationCondition determination Degree of polymerization DPAgeing of the paper insulationCondition determination Partial dischargesPD Paper ageing, ageing of the insulation system Condition determination Polarisation and depolarisation currents PDCWater content in the paper insulationCondition determination Infrared measurements IROverload, failure of the cooling system Condition determination and for fault location Acoustic measurements AMPD-detection and locationFor fault location Frequency responseFRAMechanical condition of the windingsAfter short circuits

55 Institute of High Voltage Engineering and System Management M. Muhr Breakdown voltage [kV] Water content [ppm] dilution emulsion Water content in oil Water content in paper Temperature High Low Moisture Karl-Fischer titration Capacitive sensors Breakdown voltage PDC Oil Analysis

56 Institute of High Voltage Engineering and System Management M. Muhr Loss Factor (tanδ) Heat losses are temperature- dependent High loss factor – thermal breakdown Limit:tanδ ≤ 5 % by T=100° C Temperature dependace of tanδ for new oil (1) and oils in operation (2,3,4) Oil Analysis

57 Institute of High Voltage Engineering and System Management M. Muhr Dissolved Gas Analysis (DGA) Key gases: hydrogen, methane, ethane, ethylene, acetylene, propane, propylene, carbon monoxide, carbon dioxide Detectable failures: thermal and electrical failure Oil Analysis

58 Institute of High Voltage Engineering and System Management M. Muhr Oil Analysis DGA - Evaluation CIGRE IEC IEEE Dörnenburg MSS / VDE-Diagnosis Rogers Duval Laborelec KEPCO Duval triangel

59 Institute of High Voltage Engineering and System Management M. Muhr Paper Analysis Polymerisation degree (DP) - In direct correlation with the mechanical strength new paper DP 1000 – 1200 paper at the end of life time DP approx A decrease in the DP value furane is going hand in hand with an increase of components - Furane dependence Oil temperature Type of oil Neutralization factor Type of paper Sludge content Moisture content of oil and paper Ratio oil / paper

60 Institute of High Voltage Engineering and System Management M. Muhr Furane Analysis Condition of paper insulation (mechanical strength) determined by degree of polymerization High performance liquid chromatograph (HPLC) Oil Analysis

61 Institute of High Voltage Engineering and System Management M. Muhr Conventional Acoustic Optical Chemical Electrical New Systems:electromagnetic wave detection, transfer functions, damped AC voltage (DAC) Partial Discharges Measurement in laboratory conventional measurement IEC Acoustic PD - measurement Optical PD - measurement Chemical PD – measurement (DGA) electrical High frequency PD - measurement Narrow band Δf ~ 10 kHz Broadband Δf ~ kHz HF/UHF method f ~ kHz Narrow band Δf < 2 MHz Measurement on-site UHF method f ~ 0,2 - 2 GHz Broadband Δf > 50 MHz

62 Institute of High Voltage Engineering and System Management M. Muhr Dielectric Diagnosis Charging and discharging measurements

63 Institute of High Voltage Engineering and System Management M. Muhr Diagnostics with Transient Test Voltages Frequency response analysis (FRA) and transfer function Low voltage impulse response (LVI) Wavelet analyse DAC-PD-measurement FRA

64 Institute of High Voltage Engineering and System Management M. Muhr Thermal and Optical Diagnostic Methods Thermography Temperature measurement with fibre optics PT-100 elements Surface acoustic wave radio transponder Visual inspection Endoscopy OKULAR LICHTQUELLE FLEXIBLES ENDE BLICKBEREICH Ocular Light source Flexible end Field of vision

65 Institute of High Voltage Engineering and System Management M. Muhr Mechanical Diagnostic Methods Transient oil pressure (short circuit) Stream analysis (oil and cooling air) Acoustic PD-locating Stream No stream

66 Institute of High Voltage Engineering and System Management M. Muhr Diagnosis of Rotating Machines Tasks Thermal monitoring Air cooling analysis Monitoring of vibrations Acoustic monitoring Chemical-analytic monitoring Magnetic monitoring Electrical monitoring

67 Institute of High Voltage Engineering and System Management M. Muhr Rotating Machines - Electrical Diagnosis Methods Impulse voltage test at windings Attenuation factor Resonance frequency of resonating circuit - Oscillogram of a decaying oscillation a)Error –free b)faulty

68 Institute of High Voltage Engineering and System Management M. Muhr Rotating Machines - Dielectric Diagnosis Time domain - Insulation resistance R iso - Insulation current i iso = f (t) Frequency domain - Capacitance - Loss factor tan  = f (  ), C, U

69 Institute of High Voltage Engineering and System Management M. Muhr (1)Dry condition (2)Humid condition (3)Dryness limit curve Cooling Heating Rotating Machines - Dielectric Diagnosis Insulation time constant  10 as criterion for the dryness limit curve  10 = R iso (600s) x C (50Hz)  10 = f (  ) Insulation time constant in dependance of the slot temperature and the insulation condition

70 Institute of High Voltage Engineering and System Management M. Muhr Rotating Machines - Partial discharge (Pd) diagnosis Pd’s - In cavities of solid insulation - In the are of the end winding - At no-perfect working protect system of mica - At vibrating parts of winding

71 Institute of High Voltage Engineering and System Management M. Muhr Physical Condition of Windings

72 Institute of High Voltage Engineering and System Management M. Muhr Discharge behaviour within Machine Windings

73 Institute of High Voltage Engineering and System Management M. Muhr Thermography as Diagnostic Tool Requirement - Increasing efficiency of power grid - Decreasing of inspection and maintenance rate Load situation - Increasing electrical power consumption - Higher loads on equipment Demand of ON-line diagnostic tools E.g. Contact less temperature measurement

74 Institute of High Voltage Engineering and System Management M. Muhr Thermography as Diagnostic Tool Material/Structure Heat Generation Temperature Surface temperature power output Surrounding Load current Resistor Voltage Conductivity Dielectric losses Temperature measurement

75 Institute of High Voltage Engineering and System Management M. Muhr Isolated Transmission Temperature Measurement High Voltage Object Temperature Sensor Coupling Signalling Transmission power supply Isolated Coupling High Voltage Object Temperature Sensor Coupling Signalling Transmission power supply

76 Institute of High Voltage Engineering and System Management M. Muhr Spot Temperature Measurement Transformer 29.8°C29.7°C29.8°C 29.6°C29.7°C 29.9°C29.8°C29.7°C29.6°C29.5°C 30.0°C29.7°C29.9°C29.7°C 30.1°C29.9°C 29.7°C29.8°C 30.0°C 29.9°C29.8°C

77 Institute of High Voltage Engineering and System Management M. Muhr Temperature Distribution Hot Cold 33°C23°C

78 Institute of High Voltage Engineering and System Management M. Muhr Thermography in HV - Systems - Applications Connections Switches Power transformers Measuring transformers Overhead lines Cable terminations Bushings Fuses Rotating Machines

79 Institute of High Voltage Engineering and System Management M. Muhr Applications of Thermography Poor contact resistance of a joint Poor contact resistance of a disconnector

80 Institute of High Voltage Engineering and System Management M. Muhr Applications of Thermography Compression connector of an overhead line Asymmetrical energy flow of a cable

81 Institute of High Voltage Engineering and System Management M. Muhr Applications of Thermography Bearing, machines © FLIR Slip-ring brushes

82 Institute of High Voltage Engineering and System Management M. Muhr Thank You for Your Attention


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