Metering system planning & procurement. G.K.Panchal

Transcription

1 Metering system planning & procurement G.K.Panchal 1

2 What is planning A definite course of actions and designing a process Involving all the process members 2

3 Goal path Desired status S t a t u s Current status Required planning Gap T1 Time T2 3

4 Different levels of planning Corporate level Divisional level Departmental level Operational level 4

5 Importance of planning Plan objective & how to achieve them Necessary for Type of organizational structure Type of meters required Experience of the type of meters Matching the requirement To reap hanging fruits Success of plan Available standards 5

6 Planning process Perception of opportunities Establishing objectives Planning the requirement Sequence out various activities Identification of alternatives Prepare back up planning Alternative source planning Evaluation of alternatives 6

7 Types of planning Corporate and functional planning Strategic & functional planning Long term / short term planning Proactive and reactive planning Formal and informal planning 7

8 Effectiveness of planning Internal inflexibilities Psychological Customer behavioral Capital investment External inflexibilities Political climate Technological change Time and cost factors The planner must have adequate knowledge on all such aspects 8

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10 Classification for planning of meters Type of meters Nature of application Location Different types of requirements Who will execute 10

11 Classification for planning of meters Type of meters Nature of application Location Different types of accessories Who will execute 11

12 Classification of Metering Type of Meter Single Phase Installations Nature of Applications Nature of Applications Location Location Three Phase Whole Current High capacity Long range meters Three Phase 4-wire CT connected Three Phase 4-wire CT/PT connected Preferred over 3 phase 3 wire meters-in vogue since years Unbalanced load on 3 phases Ease of tamper detection 12

13 Classification of Metering Type of Meter Type of Meter Single Phase Three Phase Whole Current Three Phase 4-wire CT connected Three Phase 4-wire CT/PT connected Installations Nature of Applications Inter Utility Meters Consumer Tariff Meters Location Location Tariff Meters Boundary Meters Substation/ Feeder Meters System Meters DT Meters 13

14 Classification of Metering Installations Type of Meter Type of Meter Location Single Phase Three Phase Whole Current Three Phase 4-wire CT connected Three Phase 4-wire CT/PT connected On Panels At Consumer Premises Indoor Meters Nature of Applications Inter Utility Meters Consumer Tariff Meters Boundary Meters At Transformers On Poles Outdoor Meters Substation/ Feeder Meters DT Meters 14

15 Classification for planning of meters Type of meters Nature of application Locations Different types of accessories Who will execute Current transformer Potential transformer 15

16 Classification of CT

17 Classification of Current transformer Bar primary Ring type tape wound Ring type resin cast Ring type plastic cased Busbar primary For transformer meter Block CT Summation CT 17

18 Classification of Current transformer Bar primary Ring type tape wound Ring type resin cast Ring type plastic cased Busbar primary For transformer meter Block CT Summation CT Large error on mismatch of load & CT ratio 18

19 Let us study Primary wound type CT and Meter for DT Metering It is for lower ratio of CT Different utilities has adopted differently the CT Installation for DT metering 19

20 Primary wound Bar Potential lead tapped from Bus & embedded in resin Cycloeliphetic resin cast CT S2 S1 20 Secondary lead of the CT For the required class of accuracy and VA burden, Primary winding becomes necessary at lower ratio

21 Existing Installation of DT Cable is connected on LT bushings of DT 21

22 Installation Process using Bar Type CT Cable is disconnected from LT bushings of DT one by one Bar CTs are bolted at same place on DT bushings Same cable is again connected on Bus of CTs 22

23 Installation using Bar Type CT Meter box can be fixed on DT 23

24 Advantages of Bar type CT installation Cable is not required to be stripped Same old Lugs can be used Special skills for threading of the cable is not required for installation Special skills for Crimping the Lugs at a height is not necessary Voltage tapping arrangement is in-built with the device Aesthetically it is good looking as CT chamber installation CT box is not required

25 Connected between the LT bushings and Load cables 3 core cable (two terminals of the CT & one terminal for the potential signal) are brought out and connected to the meter 25 Typical problems faced are CT reversals & wrong phase association at the meter

26 Evolved design process to get it right It is these small but critical things that matter Not only colour coding but Stripe code for polarity Single stripe for S 1 of CT Double stripe for S 2 of CT Special control cables to address foolproof wiring in installation TN-64 Capability Demo 30 th May Please observe these stripes No stripe for Potential

27 Factory fitted CT and meter with box on DT 27

28 For Higher ratio of CT Let us study Bar type CT and Meter for DT Metering Since Bar CT provides adequate VA burden and Accuracy class Different utilities have adopted different CT Installation methods for DT metering 28

29 Loose CT and Loose control wiring Chances of CT getting open and PT missing are very high 29 Butterfly CT is ideal solution

30 Butterfly type - I 30

31 Potential lead tapped from Locating Member For mounting on bushing stud Locating member keeps the same Central axis for the CT & the Stud

32 For mounting on bushing stud Also serves the purpose of tapping potential signal 32

33 Factory fitted CT and meter with box on DT 33

34 Potential transformer Oil filled Epoxy cast Air cooled Gas cooled Outdoor Indoor 34

35 Welded chamber Designed kiosk with CT/PT and Meter in one Cubical Meter CT PT 35

36 These are rarely noticed Suitable & reliable instruments for site testing were not available in past Suitable methods to test secondary wiring error & burden were not available Normally, meters alone are planned & tracked CT/PT & wiring impact Why? Meter Impact It s been a practise since ages Utilities are perhaps unaware of the large loss / impact due to CT/PT

37 400 volts 11,000 Volts Role of CT & PT They scale down with acceptable ratio & phase relationship 400 Amp Primary Current 11,000 Volts Primary volts Voltage Ideal CT & PT No leakage impedance No losses No excitation current Volts Secondary Voltage Such ideal CT PT can never be manufactured 5 5 Amp Secondary Current

38 Why PT/CT have errors This contributes These currents are required to Ratio error for operation of the CT/PT PT / CT needs Current to magnetize the magnetic circuit Current for leakage impedance These Currents produce some voltage drop in PT/CT Primary & secondary currents are never perfectly in phase Phase error For example, a Class 0.5 CT (say 100/5 Amps) typically delivers an uncertain to Amps in secondary at full primary current of 100 Amps To ascertain Ratio & Phase angle error we need to test it using a standard CT/PT comparator

39 For Current Transformer IEC For Potential Transformer IEC Applicable Standards These standards are applicable while purchasing a new CT or PT Let us see what the Standards say

40 Permissible Ratio errors (0.5 Class CT) 2.0% 1.5% 1.0% 0.5 s Class CT (expensive special class CTs with stringent tolerances) Normal 0.5 Class CT % Ratio Error 0.5% 0.0% 0% 20% 40% 60% 80% 100% 120% -0.5% -1.0% -1.5% -2.0% % Load

41 Permissible Phase errors (0.5 Class CT) Primary current Exaggerated view Phase Error (Min) % 20% 40% 60% 80% 100% 120% Ideal Secondary current Error due phase angle Phase angle error Actual secondary current due to core magnetizing current Normally engineers are more concerned about ratio errors, Magnetizing % Load but phase current angle of errors core that causes phase angle errors also contribute significantly

42 Permitted error limits for (0.5 Class PT) Class 0.5 (at 100% Burden) Ratio Error +/- 0.5% Phase Angle Error +/-20min This is effect of a CT/PT which conforms to Standards (at 0.8 pf load) Phase Angle errors contribute significantly to the overall error of CT/PT

43 Accuracy drifts over the life time It is necessary to re-confirm accuracy periodically Usually nameplate ratio of CTs / PTs are assumed to hold good Expensive CTs / PTs of 0.5 class are procured But DISCOM are not equipped to reconfirm the % error of CT/PT

44 What happens after installation? Accuracy drifts over time Ageing, temperature cycling, humidity etc. Inter turn shorting Iron core related causing drift in ratio & phase errors Drifting in magnetic characteristic Core saturation due to zero sequence current Fault and switching surges causing ratio errors Connected burden, lead length drops, loose connections etc. that affect secondary voltage of PTs This drifting is generally on the negative side 2.2% error (or 3.6% error) of the new CT/PT gets far worse & we don t know without testing how bad it has gone Every 1% error (for 1 MVA) leads to as much as Rs 2.35 lakhs per annum at 0.9 pf (@ Rs 3 per kwh)

45 Burden and Load for Accuracy Testing Accuracy is tested at multiple points (as per standards) to determine its full range behaviour CT Burden % and 25 % Load %, 100 %, 20 % & 5 % PT Burden % It is a tough job, tougher still because it needs to be done at customer premises Eight test points per CT 8 X 3 units One test points per PT 1 X 3 units Total 27 test results

46 Methods to test CT/PT Primary Injection (Direct Testing) Normally used by Testing Laboratories & Manufacturers Mathematical Testing ( Indirect Method ) Suitable for on site testing Red Phase instrument Quick set up No environmental impact Results are logged No chance of error 46 Time consuming Environmental impact Chances of errors are high

47 DG set How do we test it? Red Phase instrument CT/PT under test

48 Generating Station-A Generating Station-B M 400kV 220kV M Inter Utility Metering M Tie Line Metering. 220kV Utility Tariff Metering M 132kV M M Grid Station Metering M Sub Station Metering M M M Sub Station Metering M M Consumer end Meters M 11kV 400V M DT Meter 48 M Feeder Meter M HT Customer HT Meter Consumer end Meters

49 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring 49

50 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 50

51 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 51

52 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 52

53 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 53

54 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 54

55 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 55

56 Customer metering ( Single Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Voltage profiling Reading power supply off Tamper detection Magnet influence Power measurement in neutral Load limiter KWH KVAH KWH last day of month-24 Hrs Maximum demand Time of day Load profile recording Power factor recording Historical billing data Optical communication port Forward energy registration Real time clock Segment test 56

57 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 57 Optical communication port Forward energy registration Calendar month

58 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 58 Optical communication port Forward energy registration Calendar month

59 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 59 Optical communication port Forward energy registration Calendar month

60 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 60 Optical communication port Forward energy registration Calendar month

61 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 61 Optical communication port Forward energy registration Calendar month

62 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 62 Optical communication port Forward energy registration Calendar month

63 Customer metering ( Three Phase ) Purpose Billing Information Revenue protection Planning & DSM Energy conservation Tariff restructuring Reading power supply off Tamper detection Magnet influence Neutral current Load limiter 15 /30 minute profiling KWH KVAH RKVAH KW KVA PF KWH last day of month-24 Hrs Tri-vector recording Maximum demand Scrolling feature Time of day Load profile recording Voltage profiling Power factor recording Historical billing data 63 Optical communication port Forward energy registration Calendar month

64 System metering Purpose Billing Information Revenue protection Planning Forecasting Generation growth & planning 64

65 Reading methods Eyeball reading MRI optical MRI RS-232 LPR PLC / DLC Dialup lines Optical fiber GSM 65

66 Scrolling display Eye ball reading MRI reading Long scrolling list increases reading duration 66

67 Billing methods Bill printing at Discom office & distributing Reading& bill printing on MRI ( Spot billing ) Reading verification & bill printing on MRI 67

68 Billing & payment collection Cash Cheque Debit / credit card Net / phone banking Direct deduction from bank account Pre payment Cash / cheque/credit card at cash counter Phone banking Net banking 68

69 Payment Systems at High-rise buildings 69

70 Seal Management Sound installation practices should incorporate seals as a guard against tampering of the meter Seal is not a lock Seals are used to detect unauthorized entry Seals are a means of security & safety for meters Seals can be made of lead, metal, engineering plastic etc. Examples of sealing methods are crimping, pressing, wrapping,seal punch, pasting(stickers) etc 70

71 Questions please?? Thank You