الوقايه فى النظام الكهربائى

Click here to load reader

Embed Size (px)

Transcript of الوقايه فى النظام الكهربائى

  1. 1. Protection in Electrical System
  2. 2. Protection . . )( . : :
  3. 3. Protection - -
  4. 4. 1 23 5 6 4
  5. 5. Auxiliary Trip Relay Alarm System IPCT IPVT VT CT + + -- 110V DC Supply bus wire50V DC Supply bus wire Main Protective Relay AC Contact Timer Trip Coil R Y B
  6. 6.
  7. 7. Quick response Simplicity Reliability Selectivity Sensitivity Economy
  8. 8. Operating time Of Relay Operating time of auxiliary Relay closing time of Circuit breaker 0 s time [s] Total operating time of protection circuit Speed :
  9. 9. Simplicity Reliability
  10. 10. Sensitivity Ks = If min / Io Ks > 1.4 - - - - .
  11. 11. Selectivity : - . - . - . - . F2 CB1 F1 CB3 CB4 CB2 A B X X X X X X X X G1 G2 C
  12. 12. Economics . : - - .
  13. 13. : . ) ( . : . : . .... :
  14. 14. Protective relays :-).( - ).( :- . -. - . - -..... . - )Fuses, MCBs( - )Protec. Relays( - - -
  15. 15. Current Relays Over Current Relays (OCR) Deferential Relays Unbalance Relays
  16. 16. Current Relays - VTsCTsDC P/S - .
  17. 17. Current Relays K L k l -+
  18. 18. a b a b c d e f I 1 2 + 2 1 a b c d f 1 2 I a b c f e 1 2 a b c d I
  19. 19. Stopper =
  20. 20. X In Sec. Sec. X In Sec. X In X In Sec.
  21. 21. R S T B K L N k l
  22. 22. T 4 L 2 1 : :
  23. 23. K l N 3i0=iR+iS+iT k IR IS IT T I0> L
  24. 24. R U + Sig Voltage Relays UVR OVR
  25. 25. If 0 0.5 1 Uph U = % of coil length Deferential Relays Why?
  26. 26. K L 3 KL kl lk i2i1 id=i1- i2 i1 i2 + Sig. 1 2 I1 I2 Deferential Relays )(
  27. 27. K L 3 KL kl lk i2i1 id=i1- i2 i1 i2 + Sig. 1 2 I1 I2 Deferential Relays : I1 = I2 , i1 = i2 & id = i1 i2 If i1 = i2 then id = 0 : I1 I2 , i1 i2 & id = i1 i2 0
  28. 28. K L 3 KL kl lk i2i1 id=i1- i2 i1 i2 + Sig. 1 2 I1 I2 Deferential Relays )10%-40%( . Actually i1 i2 : - Vector group of protected Tr. - n1 n2 - Outside S/C. - Prim. Curr. of Protected Tr. Sec. Curr. - Protected Tr. Have ON Load Tap Changer. Relay (3) isn't instantaneous relay
  29. 29. i CT2 CT1 IPVT1 IPVT2 MT
  30. 30. CT1 CT2 CT3 IPVT2 IPVT3 IPVT1 U1 U2 U3 YY d Yy0 Yd5 Yd5 Yy0 Yd5 I1 I2 i1 i1 i3 i2 i3 i2
  31. 31. n=5 1 0 I i CTs Characteristics 5In Point of saturation 10In n=10 2 n=20 3 20In I Unbalance Current
  32. 32. K LKL kl lk i2 i1 id = i1- i2=0 i1 i2 1 5 3 2 4 + is=1/2 (i1+ i2) Differential Coil Stabilizing Coil
  33. 33. A idl is iop iop min i2 op = i2 op min + K2 s i2 s Ks = tg Ks MMF I2 iS = 0 F in spring Unbalance current Operating Characteristics
  34. 34. K LKL kl lk i2 i1 2i = i1- i2 i1 i2 1 5 3 2 4 + 0= (i1+ i2) I1 I2
  35. 35. is=1/2(i1+i2) id= i1 - i2 TS Td i1 i2 I1 I21 2 3 4 Principal of electrical Balance Relay 5 + Closing Opening
  36. 36. Moment I iop = iop min + Ks is Ks = tg KS & = f(N2 of TS or R) Not applicable characteristics Unbalance current Operating Characteristics Non linear resistance or EMF In stabilizing circuit A B a b idl In xIn is iop iop min
  37. 37. I1 I2 I> i1 i2 i1 i2 id = i1 i2 N2 N2 Ns Ns NdNi i2 i2 d s i s Protec. Element Magnetic Balance Relay
  38. 38. Directional Protection Relays 0.2 s0.4 s0.6 s 0.8 s 0.2 s0.4 s0.6 s If If If If If Supply 0.2 s0.4 s0.8 s Why?
  39. 39. : . . P = KU I Cos 90 0 P > 0 if or 0 270 Else P < 0
  40. 40. 1 4 3 i ir I iu 2 u ur . Mr = K Ur ir Cos(r + ) - Mm :Mr r . . K . Mm ) ..... Mr = 0 or >0 or 0 or 0 , Lagging > Complex form Of TL >> Geographical & Natural Conditions become more Difficult Probability of Faults becomes more & more request the protective relays to have a high speed to eliminate the faults as quick as possible. 0.20.40.60.811.2 1.210.80.60.40.2 Solution: top as If >> - Zfault >> so U >> top >>
  41. 63. LiLu U i u = cu1 USC i = ci1 ISC Fu = cu2 u2 Fi = ci2 i2 Fu Lu= Fi Li cu u2 = ci i2 (u/i)2 = ci/cu = k1 2 u/I = cu1 USC/ci1 ISC= c Z Z = k1/c = K
  42. 64. SC K Z0 = K Z = k1/c = K R2 + X2 = K Rarc
  43. 65. U i ki u ki 2 = i2 z = u/i z k 2 = 1 Its a vector has ohm character If the angle between k & z is then : z2 2zk cos + k2 = 1
  44. 66. z2 2zk cos + k2 = 1 k sc Z = Kz Z2 2ZkK cos + (kK)2 = K2 kK sc K
  45. 67. K sc K For k = 1 Z2 2ZK cos + K2 = K2 MOH Relay
  46. 68. K=0 1 i U-ki |u-ki| |i|+ Sig.
  47. 69. New Criteria : top (U, 1/If) Distance Relays top = K U/If = K Zline Zline = Z1 * L & U = I * Z1 * L These Relays called : Impedance or Distance Relays Impedance of length unit Distance R - FVoltage where the Relay build in
  48. 70. + + + - - - S D M F T
  49. 71. t (s) L (Km) t4 t3 t2 t1 L1 L2 L3
  50. 72. Distance Relays Utr >> & Ltr >> Protective Distance >> Ptr >> Znor. Cond. or ZO/L Zop Operating Conditions Zline < Zset .
  51. 73. Distance Relays . B A B A jX R ZL between A & B Rarc + Rf.point At ideal cases relay Should operate, if the measured impedance Less than A-B & s s : S/C angle of faulty line. To be relay operated correctly for any fault happened a long A - B it should has the characteristics above. But when S/C accurse there is an additional ohm resistance Added to the line impedance. Because of S/C arc. S ZS Zn At normal cases 0
  52. 74. Distance Relays : Us/Is = Zs Impedance Us/Is Coss = Zs Coss = Rs Resistive Us/Is Sins = Zs Sins = Xs Reactance Is/Us= 1/Zs = Ys Admitance Is/Us Coss =Ys Coss = G Conductance Is/Us Sins =Ys Sins = B Suseptance
  53. 75. Distance Relays )Impedance Relays( . Zop = const. Line D D jX R Zop If Z < Zop Relay will Operate Because of Z not f() so This type of relay need Directional unit, D - D Making new reconnections on the relay terminals, the circle can Be moved left, up, right or down.
  54. 76. Distance Relays D D R jX Zo Line Zop s Zo = Zop min Zo = Zop Cos(s - ) = f() According to internal angle in the relay () Which determine Zop.min we can draw the following char. This type of relay need Directional unit, D - D
  55. 77. Zo = Zop Coss = Rop = const For = 0 Distance Relays Changing internal angle () We'll obtained deferent Kinds Of Characteristics jX R D D R0 Rop Line s
  56. 78. Zo = Zop Sin s = Xop = const = 90 Distance Relays jX R D D Xop Zop Line s
  57. 79. : MHO Relays Line S Zop jX R =45 1/Zop * ( Cos (s - )) ).( = 45 Relay will operate when Z < Zop No need directional unit for this type of relays This Relay Called MHO Relay as an Opposite of OHM Relays.
  58. 80. MHO Relays jX R Line S =0 Conductance Characteristics
  59. 81. jX R Line S =90 Reactance Characteristics MHO Relays
  60. 82. : MHO Relays S jX R Zop ZS Zop jX R
  61. 83. : Ra = 28700/(I1.4) /m (0.5 - 5) (5 50)
  62. 84. . For Impedance Relays Ra ZS Zm jX R For MHO Relays (R) Ra ZS Zm jX R
  63. 85. For MHO Relays (X) Ra Zm ZS jX R
  64. 86. Impedance Relays Ra Zm ZS jX R
  65. 87. Resistance Relays RaZS Zm jX R
  66. 88. Inductance Relays jX Ra ZS Zm R