Partial Discharge Monitoring

PARTIAL DISCHARGE MONITORING

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ELECTRICAL DISCHARGESTHE PASSAGE OF ELECTRIC CURRENT THROUGH MATERIAL WHICH NORMALLY DO NOT CONDUCT ELECTRICITY. HAPPENS WHEN THE MATERIAL IS SUBJECTED TO VERY STRONG ELECTRIC FIELD. GENERALLY TRANSIENT IN NATURE, BUT MAY BE STATIONARY WHAT HAPPEN IN A DISCHARGE?ENORMOUS INCREASE IN CONDUCTIVITY

EXAMPLESPARTIAL DISCHARGES CORONA DISCHARGES LIGHTNING6/29/2009 Asean Residential School in Electric Power Enginering 1


1.1 PARTIAL DISCHARGESWHAT IS PARTIAL DISCHARGELOCALISED DIELECTRIC BREAKDOWN OF A SMALL PORTION OF A SOLID OR LIQUID INSULATION UNDER HIGH VOLTAGE STRESS. ELECTRICAL DISCHARGES THAT DOES NOT BRIDGE THE ENTIRE SPACE BETWEEN THE ELECTRODES

NATURE MAY OR MAY NOT EXHIBIT VISIBLE DISCHARGE SPORADIC THAN CORONA DISCHARGE

1.2 TYPES OF PARTIAL DISCHARGESINTERNAL DISCHARGES SURFACE DISCHARGES CORONA DISCHARGES ELECTRICAL TREES6/29/2009 Asean Residential School in Electric Power Enginering 2


1.2.1 INTERNAL DISCHARGESOCCURS IN INCLUSIONS OF LOW DIELECTRIC STRENGTHDischarges Cavities HV

Ground

INCLUSIONS CAN OCCUR IN THE FORM OF; GAS-FILLED CAVITIES OIL-FILLED CAVITIES DIRTS, PAPER, TEXTILE FIBRES OTHER FOREIGN PARTICLES

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1.2.2 SURFACE DISCHARGESOCCURS WHEN THERE OCCURS STRESS COMPONENT PARALLEL TO THE DIELECTRIC SURFACEHV

Ground

THIS MAY OCCUR IN; BUSHING END OF CABLE OVERHANG OF WINDING ANY POINT ON INSULATOR SURFACE BETWEEN HV POINT & EARTH6/29/2009 Asean Residential School in Electric Power Enginering 4


1.2.3 CORONA DISCHARGESELECTRICAL DISCHARGES CAUSED BY THE IONIZATION OF THE MEDIUM SURROUNDING THE CONDUCTOR A LUMINOUS PARTIAL DISCHARGE FROM CONDUCTORS DUE TO IONIZATION OF AIRHV

Ground

CORONA CAN OCCUR IN AIR AND GAS SUCH AS SF6 CORONA HAS SEVERAL DAMAGING EFFECTS CORONA ALSO HAS MANY USEFUL APPLICATIONS6/29/2009 Asean Residential School in Electric Power Enginering 5


1.2.4 TREESSTARTS FROM DEFECTS IN INSULATION BREAKDOWN MAY OCCUR IN EXTREMELY SHORT PERIODHV

Ground

TWO TYPES OF TREES; ELECTRICAL TREES WATER TREES DISCHARGE MAY BECOME VERY UNSTABLE CAUSING TREES TO GROW RAPIDLY TREE FORMATION MAY TAKE TIME FROM HOURS TO YEARS6/29/2009 Asean Residential School in Electric Power Enginering 6


2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENTWITHIN SOLID INSULATIONGASEOUS OR OIL CAVITY SHARPED0EDGED CONDUCTOR EMBEDDED IN SOLID SURFACE CONTAMINATION

STATOR WINDING INSULATIONLOOSE OVERHEATED CONTAMINATED

DIRT ACCUMULATION ON INSULATOR AND ARRESTER SURFACEAsean Residential School in Electric Power Enginering

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2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENT (contd)CABLEJOINTS AND TERMINATION CONDUCTIVE PROTRUSIONS IN DIFFERENT INTERFACES MECHANICAL DEFECTS TRANSPORT & INSTALLATION

WITHIN SOLID INSULATIONGASEOUS OR OIL CAVITY SHARPED0EDGED CONDUCTOR EMBEDDED IN SOLID SURFACE CONTAMINATION

TRANSFORMERSAsean Residential School in Electric Power Enginering

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2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENT (contd)CONTAMINATED GIS APPARATUSMETALLIC PARTICLEFLOATING FIXED

MICRO-PROTRUSION TRIPLE-POINT JUNCTION

BUBBLES WITHIN LIQUID INSULANTAsean Residential School in Electric Power Enginering

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3. EXAMPLE OF DISCHARGE SIGNAL 3.1 PULSES IN A.C. VOLTAGE

PULSES VERY STATISTICAL VERY RANDOM IN NATURE BURST TYPE PULSE OCCURS IN ANY HALF CYCLE

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3.2 EXAMPLE OF DISCHARGE PULSES DUE TO DAMAGED CABLE JOINT

SIGNAL OBTAINED FROM OPTICAL RECEIVER VERY RANDOM IN NATURE

SIGNAL RECEIVED FRON CAPACITIVE COUPLERAsean Residential School in Electric Power Enginering

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4. EFFECTS OF PARTIAL DISCHARGESMAY BE SERIOUS & LEADING TO BREAKDOWN CUMULATIVE EFFECT MAY LEADS TO TREEING REPETITIVE PROCESS MAY CAUSE IRREVERSIBLE MECHANICAL & CHEMICAL DETERIORATION CAN CAUSE TRACKING EQUIPMENT DAMAGE ELECTROMAGNETIC INTEFERENCE OZONE PRODUCTION POWER LOSS Asean Residential School in ElectricPower Enginering

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5. MONITORING OF PARTIAL DISCHARGES 5.1 INTRODUCTIONPD MONITORING PROVIDES EFFECTIVE EVALUATION OF POWER SYSTEM APPARATUS OR COMPONENTS ON-LINE MONITORING PROVIDES INFORMATION ABOUT PROGRESSIVE DEGRADATION UNDER OPERATIONAL STRESS AVOID COSTLY BREAKDOWN COMPLEMENTS OTHER ON-LINE MONITORING SUCH AS VIBRATION AND TEMPERATURE EFFECTIVE TOOL FOR CONDITION-BASEDMAINTAINANCE THE TREND OF PD ACTIVITY GIVES INFORMATION ABOUT AGING MECHANISM MONITORING ALLOWS THE COLLECTION OF SUFFICIENT DATA FOR RELIABLE MAINTAINANCE ALLOWS PREDICTIVE MAINTAINANCE Asean Residential School in ElectricPower Enginering

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5.2 WHAT PD MONITORING INVOLVEAT LEAST FOUR PROCESS ARE REQUIRED FOR EFFECTIVE DISCHARGE MONITORING ACTIVITIES; DETECTION OF THE DISCHARGE ELECTRICAL OR NON-ELECTRICAL METHODS MEASUREMENT OF THE DISCHARGE QUANTITIES ELECTRICAL LOCATION OF THE DISCHARGE SITE NON-ELECTRIC, SEPARATION OF ELECTRODES, ELECTRIC PROBES, TRAVELLING WAVES EVALUATION RECOGNITION, MECHANISM, EVALUATION6/29/2009 Asean Residential School in Electric Power Enginering 14


5.3 DETECTION OF PARTIAL DISCHARGESPARTIAL DISCHARGE MEASUREMENT OR DETECTION USEFUL AS DIAGNOSTIC TOOL FOR ELECTRICAL POWER EQUIPMENT DETECTION & MEASUREMENT TECHNIQUES DEPEND ON TYPES OF POWER SYSTEM EQUIPMENT OR APPARATUS PARTIAL DISCHARGES CAN BE DETECTED USING ELECTRICAL AND NON-ELECTRICAL METHODS

5.3.1 ELECTRICAL METHODS

WIDELY USED USE OF CAPACITIVE, INDUCTIVE AND CAPACITIVEINDUCTIVE SENSORS ON-LINE AND OFF-LINE IMPORTANT QUANTITIES INCLUDES APPARENT CHARGE, PD INCEPTION VOLTAGE, NUMBER AND DISTRIBUTION OF PD-PULSESAsean Residential School in Electric Power Enginering

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5.3.1.1 BASIC ELECTRICAL DETECTION CIRCUITSAMPLE

HV SOURC E

COUPLING CAPACITOR

Z

AMP

DSO

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5.3.2 NON-ELECTRICAL METHODSCAN DETECT DISCHARGE BUT CANT MEASURE CHARGE MAGNITUDE CAN LOCATE DISCHARGE SITES EXAMPLES OF NON-ELECTRICAL TECHNIQUES; CHEMICAL TRANSFORMATION GAS PRESSURE HEAT ACOUSTIC OPTICAL

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5.4 MEASUREMENT OF ELECTRICAL DISCHARGE QUANTITIESCHARGE TRANSFER APPARENT CHARGE DISCHARGE ENERGY DIELECTRIC LOSSES INTEGRATED QUANTITIES6/29/2009 Asean Residential School in Electric Power Enginering

q1 = (b + c )V

q = bV2 2 1 p = c U+ U 2

[(

) ( )]

1 W= (b+c)V2 218


5.5 LOCATION OF DISCHARGE SITESDETECTION OF THE POSITION OF DISCHARGING SITE LOCATION OF SITE ALONG LENGTH OF SAMPLE ONLY NON-ELECTRIC TECHNIQUE ACOUSTIC SEPARATION OF ELECTRODES ELECTRIC PROBES OR ANTENNAS LOCATION IN CABLE BY TRAVELLING WAVES TRAVELLING WAVE FOR SHORT CABLE AND SWITCHGEAR

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5.6 EVALUATION OF DISCHARGE ACTIVITYDETERMINATION OF THE TYPES ESTIMATION OF THE DANGER POSEDHARMFUL WHETHER MINIMUM DETECTED DISCHARGE IS SAFE

THREE PARTS;RECOGNITION THE TYPE OF DISCHARGE IS IDENTIFIED MECHANISM MECHANISM LEADING TO DETERIORATION EVALUATION WHAT IS THE PERMISSIBLE DISCHARGE LEVELAsean Residential School in Electric Power Enginering

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6. REQUIREMENT FOR DISCHARGE MONITORING TECHNIQUE OR SYSTEMABLE TO DETECT THE SMALLEST DISCHARGE ABLE TO DETECT DISCHARGES FROM ANYWHERE ABLE TO DETECT THE PHASE ON WHICH DISCHARGE OCCUR ABILITY TO IDENTIFY DEFECTS OR DAMAGE OF THE APPARATUS ABILITY TO LOCATE PRECISELY THE POSITION NOT AFFECTED BY EXTERNAL INFLUENCES SHOULD BE ABLE FOR ON-LINE APPLICATION FACILITY FOR REMOTE OPERATION

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6.2 WHAT ARE REQUIREDCHOICE OF VOLTAGE VLF VOLTAGE SERIES RESONANT VOLTAGE SOURCE OSCILATING VOLTAGE UNIPOLAR IMPULSE VOLTAGE CHOICE OF SENSORS SOLENOID COIL SENSOR METAL FOIL ELECTRODE SENSOR INTERNAL SHEILD ELECTRODE RESONANCE HF SENSOR DIRECTIONAL COUPLER EMBEDDED CAPACITIVE SENSOR6/29/2009 Asean Residential School in Electric Power Enginering 22


7. EXAMPLE OF ON-LINE PD MONITORING PROJECTTHE PROJECT INVOLVES ASSESSING HYDROGENERATOR STATOR WINDING CONDITION IN CANADIAN ELECTRICAL UTILITY IT COVERS A PERIOD OF OVER 10 YEARS PROVIDING OVER 37000 TEST RESULTS THE ON-LINE SYSTEM DEVELOP SEPARATES PULSE SIGNAL FROM ELECTRICAL NOISE REDUCE FALSE INDICATION BY MAXIMISING SIGNAL TO NOISE RATIO DETECTOR FRQUENCY GREATER THAN 40MHz FACTORS USED IN THE ANALYSESOPERATING VOLTAGE OF STATOR WINDING RATED POWER INSULATION TYPE WINDING AGE WINDING MANUFACTURER

THE SUCCESS OF THE SYSTEM IS INDICATED WHEN 50% OF UTILITY GENERATORS ARE EQUIPPED WITH THE SYSTEM6/29/2009 Asean Residential School in Electric Power Enginering 23


7.1 OUTCOME OF THE PROJECT (contd)ON-LINE PD MONITORING HAS BECOME PROVEN TOOL TO HELP ENGINEERS IDENTIFY WHICH GENERATOR NEED OFF-LINE TESTING, INSPECTION AND/OR REPAIR THE DATABASE ALLOWS THE TEST USERS TO IDENTIFY WHICH GENERATORS ARE LIKELY TO SUFFER FROM INSULATION DETERIORATION THE PD LEVELS DEPEND ON THE OPERATING VOLTAGE, MANUFACTURER AND THE SPECIFIC TYPE OF PD SENSOR AND INSTRUMENTATION USED THE PD TREND OVER TIME ALLOWS THE ENGINEER TO IDENTIFY WHICH STATOR WINDING NEED MAINTAINANCE. FOR THIS, ALL DATA MUST BE COLLECTED AT THE SAME OPERATING VOLTAGE, LOAD, WINDING TEMPERATURE AND HUMIDITY SIMILAR MONITORING SYSTEM HAS BEEN DEVELOPED FOR MOTOR, SWITCHGEAR AND DRY-TYPE TRANSFORMER

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7.2 PD MONITORING FOR GIS SUBSTATIONTHE DETECTION AND MEASUREMENT USES UHF COUPLER THAT MEASURES THE RESONANCE PRODUCED BY DISCHARGE PULSES IT WAS USED IN A 420KV GIS SUBSTATION AND THE MONITORING DONE OVER 2 YEARS THE SYSTEM WORKED EXTREMELY WELL AND VERY RELIABLE BASED ON THAT EXPERIENCE, FURTHER IMPROVEMENT HAS BEEN MADE BY INCORPORATING THE FACILITY FOR CYCLE-BY-CYCLE 3-D DISCHARGE DATA WHICH CAN BE VIEWED ON-LINE, TIME AND LOCATION TAGGED AND THE DATA STORED FOR FUTURE RETREIVAL AND INTERROGATION LATEST SYSTEM INCORPORATE EXPERT SYSTEM WHICH ALLOWS FASTER AND MORE ACCURATE INTERPRETATION OF THE DATA FOR HIGHER SUPPLY RELIABILITYAsean Residential School in Electric Power Enginering

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8. MAKING MONITORING MORE EFFECTIVE 8.1 REQUIREMENTSSUFFICIENT DATA DATA OF PD ACTIVITY FROM VARIOUS SOURCESSUSBSTATIONS OF VARIOUS AGES EQUIPMENT/APPARATUS OF VARIOUS; AGES TYPES MANUFACTURERS

DETAIL RECORDS OF DATA AND/OR OBSERVATION ELIMINATION OF NOISE DEVELOP EXPERIENCE OPPORTUNITY AND TRUST SHOULD BE GIVEN TO PERSONNEL EXCHANGE OF INFORMATION

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8.I WHAT EFFECTIVE MONITORING GIVESMORE ACCURATE INTERPRETATION OF DATA OR OBSERVATION AVOID FALSE INDICATION MORE EFFECTIVE MAINTAINANCELOW MAINTAINANCE COST

AVOID EQUIPMENT / APPARATUS DAMAGE AVOID OUTAGE INCREASE SUPPLY SECURITY & RELIABILITY ABILITY TO PREDICT THE LIFE SPAN OF THE APPARATUS6/29/2009 Asean Residential School in Electric Power Enginering 27


9. CHALLENGE IN PD MONITORINGTHE GREATEST CHALLENGE TO ALL ELECTRICAL UTILITIES IS IN MAKING THE BEST INTERPRETATION OF THE PARTIAL DISCHARGE SIGNALS

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10. STANDARDSSOME RELEVANT INTERNATIONAL STANDARDS TO BE REFERRED;

IEC 60270:2000/BS EN60270:2001HV TEST TECHNIQUE-PD MEASUREMENTS

IEEE 400-2001IEEE GUIDE FOR FIELD TESTING AND EVALUATION OF THE INSUALTION OF SHIELDED POWER CABLE SYSTEMS

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THANK YOU FOR YOUR ATTENTION

Professor Dr. Ahmad Bin Darus Dean Faculty of ELectrical Engineering Universiti Teknologi Malaysia 81310 UTM Skudai Johor Darul Takzim

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Documents

Partial Discharge Monitoring