Substation Preventive Maintenance

Transcription

1 Substation Preventive Maintenance PROVINCIAL ELECTRICITY AUTHORITY 1

2 Presentation Contents 1) A kind of substation 2) Electrical equipment details of AIS substation 3) Electrical equipment details of GIS substation 4) Preliminary operation before preventive maintenance 5) Preventive maintenance operation details of AIS substation and GIS substation 2

3 A kind of substation 1) AIS Outdoor substation 2) GIS Indoor substation 3

4 Electrical Equipment Details of AIS substation 1) 115 kv Switchyard 1) Gas Circuit Breaker 2) Disconnecting & Earthing Switch 3) Current Transformer 4) Voltage Transformer 5) Lightning Arrester 6) Protection Relay 7) Digital Multimeter 2) 115/22 kv Power Transformer 3) Station Service Transformer 4) Distribution Board 5) 22 kv Switchgear 1) Vacuum Circuit Breaker 2) Load Break Switch 3) Current Transformer 4) Voltage Transformer 5) Protection Relay 6) Digital Multimeter 7) Bus Bar 8) Power Cable 6) Battery & Battery Charger 7) Grounding 4

5 Electrical Equipment Details of GIS substation 1) 115 kv Gas Insulated Switchgear 2) 115/22 kv Power Transformer 3) Protection & Control Board 4) Lightening Arrester/Surge Counter 5) Station Service Transformer 6) Distribution Board 7) Battery & Battery Charger 8) Grounding 9) 22 kv Switchgear 1) Vacuum Circuit Breaker 2) Load Break Switch 3) Current Transformer 4) Voltage Transformer 5) Protection Relay 6) Digital Multimeter 7) Bus Bar 8) Power Cable 5

6 Preliminary operation before Preventive Maintenance 1) Visual inspection of electrical equipment inside substation 2) Thermo-scan an electrical equipment inside substation before and after preventive maintenance 6

7 Preliminary operation before Preventive Maintenance 7

8 Preliminary operation before Preventive Maintenance 8

9 Thermoscan (Before After) Classification : Minor. - > Normal Description : Probably poor connection Recommendation : Should be checked and cleaned the indicated connection point. Criteria of temperature - Temperature normal : less than 40 ºC - Temperature dangerous : more than 40 ºC Before Visible Image After 9

10 Thermoscan (Before After) Before Visible Image After 10

11 Preventive Maintenance operations details of AIS substation and GIS substation 11

12 115 kv Disconnecting & Earthing Switch Electrical Test - Insulation Resistance Test Insulation resistance test of each pole to ground by energize voltage 2500 Vdc for 1 min with switch open, shall be exceed than 100,000 MΩ - Contact Resistance Test It will be made across the main contact with switch close by energize 100 Adc, and value compare by factory test should be very less. - Operating Interlocking Check When ground bar is closed, It should not operate to close with mechanic interlocking. 12

13 96 kv, 108 kv Lightning Arrester Visual Inspection - Support Structure - Seal and Body - Grounding System - Cleaning Electrical Test - Insulation Resistance Test Energize 5,000 Vdc for 1 min on each arrester, phase to ground. The value shall be exceed more than 100,000 MΩ - Counter Operation Test Verify correct operation of surge counter by input about 100 Vdc (by capacitor 300mF) at top and bottom of surge counter and counter should count up - (Optional) DC Hi-Pot Test Power frequency voltage test on the main circuit for 1 min at lease 62% of maximum test voltage, should have a few difference leakage current of each phases 13

14 115 kv Voltage Transformer & Current Transformer Electrical Test - Insulation Resistance Test Insulation resistance test of primary winding and secondary winding with respect to ground at voltage 2,500 Vdc for 1 min. The value shall be exceed more than 1,000 MΩ - Turn Ratio Test Verification check by voltage method, measure a turn ratio of each phase and each tap by energize current following nameplate (such as 1000 A for CT, 150 A for VT) between HV and LV in every core Then, read the ratio value from a test instrument in A. analyze the value of turn ratio in the every core, the different value should be very less comparing by nameplate shall not deviate more than 0.5% 14

15 115 kv Voltage Transformer & Current Transformer Electrical Test - Winding Resistance Test Measure a secondary winding resistance of each phase by energize DC current ( 1 A or 5 A follows its nameplate) between HV and ground in every core at full tap. Receive the value of V and calculate to R from a test instrument in Ω and analyze the value, the different value should be very less and/or comparing by factory test 15

16 115 kv Gas Circuit Breaker (SF6) Electrical Test - Insulation Resistance Test Insulation resistance test at 5000 Vdc between top and middle, and between middle and case for 1 min, shall be exceed than 100,000 MΩ - Contact Resistance Test It will be made between the upper fixed contact through the GCB to the lower contact points (top to middle) with GCB close at 100 Adc, the different value should be very less comparing by factory test - Operating Timing Test Energize 125 Vdc at coil for operate GCB to change position to close and open and catch that time in use for compare with factory test. 16

17 115 kv Gas Insulated Switchgear (115kV GIS) Visual Inspection - Support Structure - Seal and Body - Motor Charging - Cleaning Electrical Test - SF6 Pressure System Test to measure pressure of each compartments by instrument (IR zero waste SF6 analyzer), compare with its nameplate and gauge (green zone) - SF6 Moisture (Dew-Point) and leakage to measure dew point by analyzer and refer to moisture inside compartments, shall be less than -30ºC Standard H2O SO2 SF6 HF IEC ppm 12.0 ppm 97 % 25 ppm 17

18 115 kv Gas Insulated Switchgear (115 kv GIS) Electrical Test - Contact Resistance Test It will be made between the upper fixed contact through the CB at 100 Adc (at the terminal box), the different value in µω should be very less comparing by factory test - Operating Timing Test Energize 125 Vdc at coil (in the terminal box) for operate CB to change position to close and open and catch that time in use for compare with factory test. - Insulation Resistance Test It test between current transformer secondary and ground usually checked by use of megger test at 1000 Vdc (500 Vdc if required) for 1 min shall be exceed than 100,000 MΩ - Winding Resistance Test Test with multi-meter, measure in Ω. - Alarm Circuit Check 18

19 Visual Inspection - Bushing, Tank and associated device - Load Tap-changer - Oil Level Check - Replace Silica Gel - Cleaning Electrical Test - Polarization Index Test Perform polarization index on each winding (primary and secondary shorting 3 phases) to ground. Energize voltage at 2,500 Vdc (about 0.5 ampare) for 1 min and 10 mins. PI should be more than /22 kv Power Transformer PI= MΩ at 10 mins MΩ at 1 min 19

20 115/22 kv Power Transformer Electrical Test - Winding Resistance Test Measure a winding resistance of each phase by energize current 10 Adc between each phase in every primary taps and secondary tap in V and calculate to Ω. Analyze the value with each phases in the same tap, the different value should be very less comparing by factory test - Turn Ratio Test Measure a turn ratio of each phase and each tap by energize voltage 10 Vac (or auto mode) between HV and LV in every tap in V. Analyze the value of turn ratio in the every tap, the different value should be very less comparing by nameplate (including phase angle difference in degree) 20

21 115/22 kv Power Transformer Electrical Test - Oil Transformer Test By IEC (ASTM if any) including Dielectric Breakdown Test at both main tank and OLTC. Standard Type Gap No. of Test Acceptable IEC Spherical 2.5 mm 6 > 60 kv ASTM D877 Plate 2.5 mm 5 > 30 kv ASTM D1816 Spherical 2.0 mm 5 > 50 kv - Water Content Test By ASTM D1533, to sampling transformer oil to test in the laboratory, shall be less than 25 ppm on main tank and less than 40 ppm on OLTC. 21

22 Electrical Test - Dissolved Gas Analysis (DGA) By ASTM D3612, to analyze key gas in transformer oil such as O 2 N 2 H 2 CH 4 CO CO 2 C 2 H 4 C 2 H 6 C 2 H 2 C 3 H 6 C 3 H 8 of main tank and OLTC. O 2 N 2 H 2 CH 4 CO 115/22 kv Power Transformer N/A N/A <100 <120 <350 CO 2 /CO CO 2 C 2 H 4 C 2 H 6 C 2 H 2 >3 <2500 <50 <65 <1 - Oil/Winding Temp. See a winding temperature at a gauge, shall be in the length of setting * Normally Setting Fan : 70 C Alarm : 95 C Trip : 105 C - Tr. Fan (Motor/Fan) See fan working by simulate all functions refer by temperature (on/off/work at high temp.), shall work by its setting 22

23 115 kv Protection & Control Board 115 kv Protection Relay Visual Inspection - Seal and Body - Setting Relay Recording - Cleaning - Relay Feature (Operation) Check - Digital Multi-meter Check Relay in testing 27/59 Under/Over Voltage Relay 50/51G Instantaneous/Inverse Time Overcurrent Relay 21 Distance Relay 87 Differential Relay 23

24 22 kv Switchgear & Bus Bar Item - Vacuum Circuit Breaker - Current Transformer - Voltage Transformer - Protection Relay - Metering - Power Cable Visual Inspection - Support Structure - Seal and Body - Bus Bar Connection - Cleaning - Motor Charging (VCB) - Terminator (Power Cable) - Record Setting Relay (Relay) 24

25 22 kv Switchgear & Bus Bar Electrical Test (VCB) - Contact Resistance Test - Insulation Resistance Test - Operation Timing Test - Operation Test Electrical Test (CT&PT) - Winding Resistance Test - Insulation Resistance Test - Turn Ratio - Contact Resistance Test Electrical Test (Power Cable) - Insulation Resistance Test Electrical Test (Protection Relay) - Secondary Injection Test 25

26 Station Service Transformer Visual Inspection - Bushing, Tank and associated device - Oil Level Check - Cleaning Electrical Test - Winding Insulation Resistance Test Perform insulation resistance and/or polarization index on each winding to ground. Recommended minimum DC test voltage at 2500 Vdc for primary and 500 Vdc for secondary. - Oil Transformer Test By IEC (ASTM if any) including Dielectric Breakdown Test. 26

27 Computerized Substation Control System (CSCS) - Visual Inspection - Cleaning - Communication System Test 27

28 AC/DC Distribution Board - Visual Inspection - Cleaning - Insulation Resistance Test (Panel) Test for 1 min on each bus, phase to ground and phase to phase with input/output off. 28

29 Battery & Battery Charger Visual Inspection - Seal and Body - Cleaning Electrical Test - Insulation Resistance Test - Charger Operating - System Function Check - Voltage Battery Cell Check Measure cell voltage compare by its nameplate and analyze its defect. - Impedance Test Measure cell resistance (impedance) between pole + and pole - in Ω compare by nearby cell and analyze its defect. 29

30 Grounding Systems Visual Inspection - Grounding System Connection Check - Torque at joint Electrical Test - Grounding Resistance Test Performed the test by fall of potential method. The resistance of grounding point should less than 5 ohm. - Grounding Continuity Test Performed the test by two points method. The resistance of ground and another ground should be very less 30

31 Insulation Resistance and Polarity Index Test 1. Prepare a test instrument (such as Megger/MIT515) 2. Measure an insulation resistance of each core by energize 5,000 Vdc between core and ground for 1 min and 10 mins with switch open 3. Read the value from a test instrument in MΩ 4. Measure in every phases and cores, then analyze the value compare by each phase in the same core, the different value should be very less but shall be exceed than 100,000 MΩ 5. PI (Polarization Index) is the value of Insulation Resistance at 10 mins divided by at 1 min, shall be above

32 Contact Resistance Test 1. Prepare a test instrument (such as Megger/MOM200A) 2. Measure a contact resistance of each coil (status close and open) by energize current 100 Adc in every phases 3. Read the value from a test instrument in µω 4. analyze the value with each phases, the different value should be very less comparing by factory test 32