220KV EHV NETWORK AT RELIANCE JAMNAGAR REFINERY COMPLEX

Transcription

1 220KV EHV NETWORK AT RELIANCE JAMNAGAR REFINERY COMPLEX

2 JAMNAGAR 220KV CABLE NETWORK: 2

3 2. DESIGN 2A. NETWORK: 220 KV NETWORK DESIGN IS DESIGNED WITH 100% REDUNDANCY FROM 220 KV BUS TO LOAD. THIS IS ACHIEVED WITH DUAL 220 & 33 KV BUSBARS, DUAL 220 AND 33 KV TRANSFORMERS AND DUAL 220 & 33 KV CABLE NETWORKS. 2B: 220 KV CABLE DESIGN TWO TYPES OF CABLE CIRCUITS WERE IDENTIFIED TO CATER TO THE NETWORK TYPE MVA CAPABILITY: SINGLE CORE 400SQ.MM XLPE COPPER CONDUCTOR CABLE IS SELECTED TO LAY IN FLAT FORMATION. TYPE-2-300MVA CAPABILITY: SINGLE CORE 1000SQ.MM XLPE COPPER CONDUCTOR CABLE IS SELECTED TO LAY IN FLAT FORMATION. 3

4 CABLE SHEATH: LEAD SHEATH IS USED TO PROTECT THE CABLE INSULATION FROM SOLVENTS PRESENT IN THE UNDERGROUND SOIL IN THE REFINERY AND PETROCHEMICAL COMPLEX. CABLE DESIGN PARAMETERS: CABLE 400SQ.MM CABLE 1000SQ.MM CABLE CONDUCTOR COPPER COPPER INSULATION XLPE XLPE METALLIC SHEATH LEAD ALLOY LEAD ALLOY METALLIC SHEATH THICKNESS 1.9MM 2.0MM OVERALL DIAMETER 97MM 108MM WEIGHT 16.6 KG/M CABLES LAID QUANTITY OF 400&1000SQ.MM TRENCHES LAID 140KM 24KM 4

5 EXECUTION AT CRITICAL LOCATIONS WHERE VEHICLE MOVEMENT CANNOT BE STOPPED AND AT THE SAME TIME DUCTING WORK WAS SUPPOSED TO BE CARRIED OUT, HDD (HORIZONTAL DIRECTION DRILLING) METHOD WAS ENVISAGED. DURING HDD JOB SOIL STRATA WAS NOT CONDUCIVE DUE TO SOLID ROCK BELOW 1METER OF THE SURFACE AND DUE TO WHICH DRILL FAILED AT SEVERAL INSTANCES. 5

6 SITE ACCEPTANCE TESTS ONCE ALL THE CABLE IS LAID THE CABLE IS TESTED WITH ALL ACCEPTANCE PROCEDURES TO SUCCESSFULLY CHARGE THE CABLE AS PER VENDOR GUIDELINES AND IEC INSULATION RESISTANCE TEST DC CONDUCTOR RESISTANCE TEST LINK BOX CONTACT RESISTANCE TEST: SVL INSULATION TEST: DC JACKET TEST: 24 HR. SOAK TEST: THIS TEST WAS PERFORMED TO ENSURE THAT THE CABLE LAID AND CHARGED ON NO LOAD IS FREE FROM ALL DEFECTS PARTIAL DISCHARGE MEASUREMENT TEST: CAPACTIVE TYPE PD MEASUREMENT SYSTEM IS BEING USED

7 CASE STUDIES: CASE STUDY-1 220KV CABLE INTERCONNECTED BETWEEN 220KV GIS MRS 4 AND C2 COMPLEX MRS-1 WAS TRIPPED AFTER WAS SUCCESSFULLY CHARGED IN JULY 16 THE CABLE FAULT COULD NOT BE LOCATED EVEN WITH 33KV CABLE FAULT LOCATOR. CABLE WAS TESTED BY KEEPING 2X105MVA POWER TRANSFORMER IN SERIES HAVING AN IMPEDANCE VALUE OF 13.25% AND THEREBY LIMITING THE FAULT CURRENT TO 1KA. NO. OF TIMES SUCH TESTING WAS CARRIED OUT, BUT CABLE IR VALUE IS FOUND NORMAL. LATER IT WAS DECIDED TO DISCONNECT THE CABLE FROM GIS TERMINATION AND TEST THE CABLE WITH SWITCH ON TO FAULT LOCATION. LATER THE FAULT WAS FOUND IN GIS AND WAS VT FAILURE SIEMENS SENT VT TO WORKS IMMEDIATELY FOR INVESTIGATION. TRACKING WAS VISIBLE ON THE EPOXY GAS TIGHT BUSHING INSIDE VT TANK. UPON RELIANCE INSTRUCTIONS HV TEST WAS PERFORMED ON THE SAME. 7

8 CASE STUDY 1 CONTINUED. 8

9 CASE STUDY-2: ROUTE SQ.MM CABLE RUNNING FROM DTA MRS4 TO C2 MRS-1 CABLE TRIPPED ON JUNE16, 2HOURS AFTER CHARGING. CABLE FAULT WAS LOCATED WITH THE HELP OF CABLE FAULT LOCATOR AND WAS 58M AWAY FROM ONE OF THE JUNCTION IN SINGLE (RED) PHASE FROM MRS4. SITE INSPECTION REVEALED PHYSICAL DAMAGE TO THE CABLE. A SHARP PHYSICAL DAMAGE WAS ALSO OBSERVED ON THE INSULATION. FURTHER TO THIS INCIDENT ALL THE METALLIC SHOVELS WERE REPLACED WITH PLASTIC TO AVOID PHYSICAL DAMAGE TO THE CABLE 9

10 CASE STUDY SQ.MM WITH DIAMETER OVER INSULATION BEING 74.1MM AND 1000 SQ.MM CABLE WITH DIAMETER OVER INSULATION 83.9MM. STRESS CONE USED AS A PART OF 220KV GIS CABLE TERMINATION DID NOT MATCH WITH THE DIAMETER OF THE CABLE RECEIVED AT SITE. STRESS CONE SUPPLIED FOR 400SQ.MM VARIED BETWEEN 76.5MM-81.5MM WHICH WAS NOT SUITABLE TO THE CABLE SUPPLIED. CABLE DIAMETER DIAMETER OVER INSULATION STRESS CONE RECEIVED AT SITE NEW STRESS CONE ENVISAGED 1000 SQ.MM 83.9MM 76.5MM TO 81.5MM 81MM TO 85.5MM 400 SQ.MM 74.1MM 67.5MM TO 72.5MM 72MM TO 75MM 10

11 CASE STUDY 4 CABLE BETWEEN STG TRANSFORMER AND 220KV GIS WAS CHARGED IN THE MONTH OF MAY 17. MINOR SPARK NEAR SUPPORT CLAMP AT THE TIME OF CLOSING THE BREAKER TO ENERGIZE THE CABLE. MANUFACTURER PERFORMED SWITCHING OVERVOLTAGE STUDY TO INVESTIGATE THE TRANSIENT STATE ASSOCIATED WITH THE ROUTE. BY EMTP SIMULATION APPROXIMATELY THE INDUCED VOLTAGE ONTO THE SURFACE OF THE CABLE WAS V. THIS SURFACE VOLTAGE OF CABLE RESULTED IN SPARK PHENOMENA BETWEEN CABLE THE INSULATOR/RUBBER CUSHION IN BETWEEN CABLE CLEAT AND CLAMP HAS NOT BEEN PROPERLY LOCATED TO INSULATE THE CABLE FROM THE CLAMP 11

12 SAT WITH EHV TEST KIT RELIANCE PROCURED THE DAC 300 MEGGER KIT TO TEST EHV CABLES AS SOAK TEST IS GETTING DIFFICULT DUE TO RELIABILITY OF THE NETWORK. THE SELECTION OF THIS TEST KIT IS MAINLY DUE TO PORTABLE IN NATURE AND PD TESTING IS POSSIBLE. HV TEST KIT IS COMMISSIONED IN AUGUST 2017.) TEST KIT INSIDE GIS TEST KIT OUTDOOR 12

13 MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION. : THE 220KV CABLE NETWORK LAID ACROSS THE PLANT IS THE HEART OF THE PROJECT AND ANY HINDRANCE TO THE POWER SUPPLY SHALL HAVE HUGE FINANCIAL EFFECTS TO THE PLANTS DEPENDING ON THIS NETWORK. SO PREVENTIVE MAINTENANCE IS ONLY SOLUTION TO AVOID ANY SHUTDOWNS. FOLLOWING IS THE SUMMARY OF MAINTENANCE ACTIVITIES PERFORMED. SR. NO. ACTIVITY DETAIL OF ACTIVITY FREQUENCY 1 ROUTE SURVEY 2 THERMOGRAPHIC INSPECTIONS 3 PARTIAL DISCHARGE (PD) MEASUREMENT UNDERGROUND: LOOK FOR ANY EXCAVATION JOBS (MANUAL/MECHANIZED) NEAR TRENCHES, STORAGE OF MATERIALS OVER CABLE TRENCH, CONDITION OF ROUTE MARKERS, EXPOSURE OF CABLE TILES DUE TO SOIL EROSION DURING MONSOON. ABOVE GROUND: THIS IS A PATROL CHECK ALONG WHOLE CABLE ROUTE LINE EXPOSED IN THE AIR TO INVESTIGATE CONDITION OF CABLE AND SURROUNDING CONDITION OF ROUTE TO ASSESS PHYSICAL DAMAGE, ARCING OR TRACKING TRACES. ONLINE: THERMOGRAPHY TO BE CARRIED OUT FOR AIS END TERMINATIONS AND SUPPORT STRUCTURE/TRAYS FOR IDENTIFYING LOCAL HEATING. ONLINE: MEASUREMENT OF PARTIAL DISCHARGES TO THE RATED OPERATING VOLTAGE USING PD SENSORS. OFFLINE: MEASUREMENT OF PARTIAL DISCHARGE USING EXTERNAL VOLTAGE SOURCE BY MEGGER DAC WEEKLY 26 WEEKS 26 WEEKS

14 MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION. : 4 SHEATH CURRENT MEASUREMENT 5 LINK BOX INSPECTION 6 EARTHING SYSTEM INSPECTION 7 PD BOX INSPECTION SHEATH VOLTAGE LIMITER(SVL) PERFORMANCE CHECK CORONA MEASUREMENT ON OUTDOOR TERMINATION HARMONIC CURRENT MEASUREMENT ONLINE: MEASUREMENT OF SHEATH CIRCULATING CURRENT, TO ASSESS HEALTHINESS. THIS MEASUREMENT WILL REVEAL SHEATH PROBLEMS LIKE EXTERNAL DAMAGE OR PIN HOLES IN OUTER SHEATH. OFFLINE: LINK CONTACT RESISTANCE, VISUAL INSPECTION OF LINK BOX FOR MOISTURE INGRESS, CORROSION, ARCING TRACE ETC. ONLINE: MEASUREMENT OF SCREEN CURRENTS IN SINGLE POLE EARTHING CABLES IN TERMINATIONS AIS/GIS OFFLINE: BONDING INSPECTION, OVER SHEATH TEST, SVL TEST, MEASUREMENT OF EARTHING RESISTANCE, CONTINUITY TEST IN EARTHING CABLES OFFLINE: INSPECTION OF PD BOX FOR MOISTURE INGRESS, CORROSION, ARCING TRACE ETC. OFFLINE: VISUAL INSPECTION ONLINE: TO DETECT INSULATION SYSTEM FOR OUTDOOR TERMINATIONS AND SURROUNDINGS WITH CORONA CAMERA ONLINE: MEASUREMENT OF HARMONIC CURRENT WITH POWER ANALYSER 52 WEEKS 3 MONTHS 26 WEEKS 52 WEEKS 14

15 MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION. : 11 INSULATION RESISTANCE OF OUTER SHEATH 12 HIGH VOLTAGE TESTING 13 INSPECTION OF CONNECTION POINT OFFLINE: IR VALUE OF SHEATH TO BE MEASURED USING DC VOLTAGE TEST. THIS IS TO BE DONE ALONG WITH OFFLINE HIGH VOLTAGE TESTING AND PD MEASUREMENT. OFFLINE: HIGH VOLTAGE TESTING TO BE CARRIED OUT BY USING EXTERNAL VOLTAGE SOURCE MEGGER DAC 300 OFFLINE: INSPECTION OF CONNECTION POINT FOR AIS TERMINATIONS TO BE CARRIED OUT FOR IDENTIFYING OVERHEATING OR CORROSION ON CONNECTION POINT OF CABLES. 15