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Today’s Session

What is ahead?. Today’s Session. Fault Level Calculations Power-system Overview PU Concept 3 Ph. Fault Level Calculations 1 Ph Fault Level Calculations O/C E/F Relay Time Coordination General information about relay characteristic Worked out example Directional Relay What is MTA

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Today’s Session

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  1. What is ahead? Today’s Session • Fault Level Calculations • Power-system Overview • PU Concept • 3 Ph. Fault Level Calculations • 1 Ph Fault Level Calculations • O/C E/F Relay Time Coordination • General information about relay characteristic • Worked out example • Directional Relay • What is MTA • How to confirm direction of relay reach while in service

  2. Fault Level Calculations

  3. Fault Level Calculations What is ahead? • Overview of transmission network. • What is mean by fault level • PU Concept • Network Modeling • Fault Level Calculation & Worked out example • Three Phase Fault • SLG Fault

  4. Fault Level Calculations Step-1 Overview of power system grid and transmission network

  5. Fault Level Calculations Typical State Level Power System & our area of interest

  6. Fault Level Calculations Typical State Level Power System & our area of interest

  7. Fault Level Calculations Local Network – or – Sub-Transmission System 400kV S/S - A S/S - C 220kV 220kV 33kV S/S - B 220kV S/S - D 132kV S/S - F S/S - E 132kV 33kV 33kV 11kV

  8. Fault Level Calculations Step-2 What is mean by fault level

  9. Fault Level Calculations What is fault level S/S - A S/S - B S/S - B 14530 MVA 14530 MVA 11300 MVA 18290 MVA 9700 MVA 9730 MVA 9730 MVA 6400 MVA 7200 MVA 8400 MVA 8400 MVA 4630 MVA 5800 MVA S/S - C 2700 MVA 3670 MVA 1185 MVA ABC Transmission Co. Ltd. 3 Ph Fault Levels For 2010-2011

  10. Fault Level Calculations S/S - B 14530 MVA 9730 MVA What is fault level-Continued…. 2450 MVA 2450 MVA 1465 MVA 1465 MVA 2200 MVA 2200 MVA 2300 MVA 8700 MVA 1030 MVA

  11. Fault Level Calculations Step-3 Understanding Per-Unit Measurements

  12. Fault Level Calculations PU Concept • PU impedance values are calculated by • For Transformers • For Lines Base MVA %ImpedanceNew Base MVA = % ImpedanceName Plate Capacity in MVA Base MVA = Ohmic Value %Impedance kV 2

  13. Fault Level Calculations PU Concept • PU impedance values are calculated by • For Transformers • %Impedance = Ohmic Value * ( Base MVA / Name Plate MVA ) • For Lines • %Impedance = Ohmic Value * ( Base MVA / BasekV2 )

  14. Fault Level Calculations PU Concept Base MVA = 200 MVA Sec A Sec B Sec C Sec D 220kV 400kV 132kV 33kV T1 L1 T2 L2 T3 L3 12 Ohm 0.4 ohm/Km 200 Km 0.4 ohm/Km 50 Km 0.4 ohm/Km 30 Km 400/220 kV 15% 315 MVA 220/132 kV 14% 200 MVA 132/33 kV 9.33% 25 MVA

  15. Fault Level Calculations Step-4 Network Modeling

  16. Fault Level Calculations PU Concept T1 L1 T2 L2 T3 L3 0.4 ohm/Km 200 Km 0.4 ohm/Km 50 Km 0.4 ohm/Km 30 Km 400/220 kV 15% 315 MVA 220/132 kV 14% 200 MVA 132/33 kV 9.33% 25 MVA

  17. Fault Level Calculations Short Circuit Current • 3 Phase Short Circuit MVA at fault point Base MVA x 100 = ---------------------------------------------------- Percentage Impedance(from source to fault point)

  18. Fault Level Calculations PU Concept-Continued XT1 XL1 XT2 XL2 XT3 XL3 9.52% 14% 33.05% 22.96% 74.64% 220%

  19. Fault Level Calculations PU Concept 75 Ohm 80 Ohm 34 Ohm 20 Ohm 65 Ohm 12 Ohm 0.4 ohm/Km 200 Km 0.4 ohm/Km 50 Km 0.4 ohm/Km 30 Km 400/220 kV 15% 315 MVA 220/132 kV 14% 200 MVA 132/33 kV 9.33% 25 MVA

  20. Fault Level Calculations Step-5 Finding Source Impedance, Worked out Example

  21. Fault Level Calculations Typical State Level Power System & our area of interest 4630 MVA 4630 Xs(pu) Base MVA= 100 Xs(pu) Xs (pu) = 0.0216 Or Xs% = 2.16%

  22. Fault Level Calculations 220/132kV Padegaon Solved Example 132kV 33kV 2850 MVA 50 MVA 10.21% 50 MVA 10.21% 132/33-11 kV Harsool 50 MVA 10.88 % 50 MVA 10.88 % 132/33-11 kV Chikalthana 0.4 Ohms / Km 132kV 33kV 25 MVA 9.73 % 25 MVA 9.73 % 50 MVA 10.03% 8 Km 25 MVA 10.04 % 25 MVA 10.04 % 25 MVA 10.52 % 11kV 0.4 Ohms / Km 25 MVA 10.21 % 5 Km 25 MVA 9.84 % 11kV

  23. Fault Level Calculations 220/132kV Padegaon Solved Example 132/33-11 kV Harsool 132kV 33kV 2850 MVA 132/33-11 kV Chikalthana 668 MVA 2257 MVA 132kV 33kV 538 MVA 1998 MVA 11kV 11kV

  24. Fault Level Calculations Unsymmetrical Faults-Sequence Network • Up till now we have discussed 3 Phase faults which are rear. Most of the fault in power system are single line to ground faults. • To find out the short circuit MVA due to single phase to ground fault it is necessary to use Sequence Network • Let us have a closer look of sequence network

  25. Fault Level Calculations Unsymmetrical Faults-Sequence Network M1 T2 L T1 G XM11 XM21 M2 XT21 XL1 XT11 Xg1 SLD F +Ve Sequence Network XM10 XM20 XM12 XM22 XT20 XL0 XT10 Xg0 XT22 XL2 XT12 Xg2 F F Zero Sequence Network -Ve Sequence Network

  26. Fault Level Calculations Single Line to Ground Fault-Sequence Network Connections XM11 XM21 X1 XT21 XL1 XT11 Xg1 F X2 XM12 XM22 XT22 XL2 XT12 Xg2 Ia = 3 / (X1 + X2 + X0) F X0 XM20 XT20 XL0 XT10 Xg0 F

  27. Fault Level Calculations 220/132kV Padegaon Single Line to Ground Fault-Solved Example 132kV 33kV 3Ph 2850 MVA 50 MVA 10.21% 50 MVA 10.21% 132/33-11 kV Harsool 1Ph 2230 MVA 50 MVA 10.88 % 50 MVA 10.88 % 132/33-11 kV Chikalthana 0.4 Ohms / Km 132kV 33kV 25 MVA 9.73 % 25 MVA 9.73 % 50 MVA 10.03% 8 Km 25 MVA 10.04 % 25 MVA 10.04 % 25 MVA 10.52 % 11kV 0.4 Ohms / Km 25 MVA 10.21 % 5 Km 25 MVA 9.84 % 11kV

  28. Fault Level Calculations Single Line to Ground Fault-Solved Example 3Ph 2850 MVA 3Ph 2850 MVA 1Ph 2230 MVA 1 Ph Short Circuit MVA at 132kV Harsool Bus 3*BaseMVA*100 ( ) + ( XS0 + (XL10 || XL20) ) 2*( XS1 + (XL11 || XL21) )

  29. Fault Level Calculations 220/132kV Padegaon Solved Example 132/33-11 kV Harsool 132kV 33kV 3Ph 2850 MVA 3Ph 2257 MVA 3Ph 668 MVA 1Ph 2230 MVA 132/33-11 kV Chikalthana 1Ph 1662 MVA 1Ph 604 MVA 132kV 33kV 538 MVA 1998 MVA 11kV 11kV

  30. Fault Level Calculations Thank You

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