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Contents CHAPTER 1 : SELECT THE CURRENT TRANSFORMER 1.1 SELECT BI FOR LINE PROTECTION (BI7) .5 1.2 SELECT BI FOR TRANSFORMER PROTECTION .6 1.2.1 Select BI1 (BI4) 1.2.2 Select BI2 (BI5) 1.2.3 Select BI3, BI6 .6 CHAPTER 2: METHOD OF PROTECTION 2.1 METHOD OF PROTECTION FOR TRANSFORMER 2.1.1 The type of faults and abnormal working mode .7 2.1.2 Method of protection 2.2 METHOD PROTECTION FOR LINE CHAPTER 3: THE PRINCIPLES OF RELAY PROTECTION IN PROTECTIVE METHOD 3.1 RESTRAINT-DIFFERENT RELAY PROTECTION 3.1.1 The principle of restraint-different relay protection 3.1.2 Restraint differential relay protection .10 3.2 BUCHHOLZ RELAY PROTECTION 12 3.3 TIME OVERCURRENT RELAY 13 3.4 OVERCURRENT ZERO SEQUENCE PROTECTION .14 3.5 OVERLOAD TRANSFORMER PROTECTION 14 CHAPTER 4: CALCULATION OF SHORT CIRCUIT 16 4.1 CALCULATION OF REACTANCE VALUE .16 4.1.1 Calculation of reactance value of element in maximum power system mode .16 4.1.2 Calculate the resistances in the minimum system capacity mode 17 4.2 CACULATE SHORT-CIRCUIT CURRENT .18 4.2.1 Calculate short-circuit current in maximum system power mode 18 4.2.2 Calculate short-circuit current in minimum system power mode 24 CHAPTER 6: CALCULATE PROTECTION FOR LINE .27 6.1 SHORT-CIRCUIT CURRENT IN SOME CASES ON LINE L 27 6.1.1 Instantaneous overcurrent relay protection 27 6.2 MAXIMUM OVERCURRENT RELAY 29 6.2.1 Maximum power system mode 29 6.2.2 Minimum power system mode .30 6.3 CALCULATE ZERO PROTECTION (TTK) .30 CHAPTER 7: CHECK THE WORK OF PROTECTION FOR THE SUBJECTS .32 7.1 CHECK THE WORK OF THE TRANSFORMER PROTECTION 32 7.1.1 Check the work of the transformer protections compare offset current with braking .32 7.1.2 Check the work of over fast cutting current 34 7.1.3 Zero sequence in earth fault ( TTK) 34 7.2 CHECK THE WORK OF THE PROTECTIONS IN THE LINE 35 7.2.1 The instantaneous overcurrent .35 7.2.2 Maximum current protection 35 7.2.3 Zero sequence in earth fault (TTK) .35 RELAY PROTECTION PROJECT Code: 43554B I Grid diagram II Initial data Content System Transformer Line Initial data SNmax (MVA) 2300 SNmin (MVA) 1700 X0HT/X1HT 1,15 SBđm (MVA) 40 U1/U2: 115/24 kV, tổ đấu dây YN/yn- 12 UN (%) 11,5 Chiều dài Loại dây XLPE-240 Z1(Ω/km) 0,11+j0,33 Z0(Ω/km) 0,32+j0,94 X0L/X1L 2,8 Pmax (MW) 11 Load 0,9 0,5s Impedance: Line type XLPE-240 : 0,119+j0,154 (Ω/km)1 13,5 xTMS Time characteristics of time overcurrent relay: t = I r −1 , with TMS is constant of times set, with time delay t= 0.5s III Performance requirements Select BI for protection Select protection for transformers B1, B2 and line L Tra bảng Sổ tay tra cứu thiết bị điện từ 0,4-500kV, Ngô Hồng Quang THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD The principles of relays protection Calculate the short circuit Calculate protection parameters of current overcurrent, overcurrent, overcurrent and earth fault protection for transformers Calculation of overcurrent protection, fast current overcurrent, overcurrent of current not set for line L Check the work of the guard for the above objects THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD CHAPTER 1 : SELECT THE CURRENT TRANSFORMER 110 kV MC1 22 kV B1 BI1 BI2 MC2 BI3 L MC7 HTÐ MC4 BI4 B2 BI6 P1 BI7 BI5 MC5 Figure 1.1 Diagram of current transformer From the protection requirement of the project, we need to select BI to serve the protection of the transformer and line L In this, BI5 is used for line protection and BI1, BI2, BI3 and BI4 for transformer protection Conditions to select BI: The rated current: The rated voltage: The secondary load: Dynamic stability current coefficient: Allowed force on top of BI's porcelain: Multiples thermal stability: With: - Dynamic stability current coefficient,, which is determined by the manufacturer - a : is the distance between phases - distance from the current transformer to the nearest porcelain support Multiples thermal stability, which is determined by the manufacturer THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD 1.1 Select BI for line protection (BI7) The maximum current working through the line L : I L lvmax=I pt max= P1 max √ U đ m cos = 11 103 =¿ 320,75 (A) √ 22.0,9 Select BI has the rated current 350A and the rated second current 5A, the rate voltage 22 kV The conversion ratio is n BI 7= 350 1.2 Select BI for transformer protection 1.2.1 Select BI1 (BI4) - Current transformer BI1 BI4 are select with the same the conversion ratio The maximum current flows through BI1 : IBI1max = kqt x S dmB √3 U Cdm = 1,4 40 103 = 293,92 (A) √3 110 Select BI has the rated primary current 300A and the rated second current 5A, the rate voltage 110 kV The conversion ratio is n BI 1= - Similar, the conversion ratio of BI4 isn BI 4= 300 300 1.2.2 Select BI2 (BI5) - Current transformer BI2 BI5 are select with the same the conversion ratio Considering the overload condition of the MBA, the maximun current flows through BI1 is: IBI1max=kqt x SdmB √3 U Hdm = 1,4 40 103 = 1469,62 (A) 22 √ Select BI has the rated primary current 1500 A and the rated second current 5A, the rate voltage 22 kV The conversion ratio is: n BI 2= - Similar, the conversion ratio of BI5 is : n BI 5= 1500 1500 1.2.3 Select BI3, BI6 We choose BI3, BI6 same BI1 so the ratio is n BI 3=n BI 6= 300 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD = [ ] 0,072 23 −(0,011+ ) = 6,25(km) 10,81 25.0,154 6,25 100%= 89,29% => Protect for 89,29% of line 6.2 Maximum overcurrent relay 6.2.1 Maximum power system mode The threshold current : with: kat –Safety factor, kat = 1,2 kmm – Open factor, kmm = kv - Return coefficient selected for digital relay: kv = 0,95 Ilvmax- The largest working current, Ictlvmax = 238,57 A Convert maximum working current to relative unit system: 23=0,38 The threshold current 0,38 = 0,96 - Construction work time characteristics: Overcurrent protection definite time : t= 13,5 x TMS I ¿ −1 with with : TMS: constant time set of relay (s) I ¿: Short-circuit current through relay 30 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD - Short circuit point N6: IN6 max = 9,01 9,01 0,96 = 9,39 Impact time characteristics at N6 t = 13,5 x TMS I ¿ −1 13,5 xTMS 1= 9,39−1 TMS = 0,62 Short circuit point N5: IN5 max = 9,88 I ¿= I N max 9,88 = 10,29 I kdI >¿ = ¿ 0,96 t = 13,5 x TMS I ¿ −1 13,5 x 0,62= 0,9(s) t5= 10,29−1 Similar calculations for short circuits on the line we have Table 6.3 Impact time of the max system IN max 21,28 12,23 10,93 9,88 9,01 Ikđ 0,96 I* 22,17 12,74 11,39 10,29 9,39 TMS 0,62 t 0,40 0,71 0,81 0,90 1,00 6.2.2 Minimum power system mode Table 6.4 Impact time of the system IN max 9,95 8,95 8,13 7,45 6,87 Ikđ 0,96 I* 10,36 9,32 8,47 7,76 7,16 TMS 0,62 t 0,89 1,01 1,12 1,24 1,36 31 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD CHARACTERISTICS OF THE TIME OF OVERCURRENT PROTECTION t max mode t mode 003 002 001 001 001 001 001 001 001 001 001 001 000 000 6.3 Calculate zero protection (TTK) -Threshold current of protection with: k0 - adjustment coefficient, k = 0,3 IdmBI - Rated current of the current transformer set for the line The working time of overcurrent protection does not have time to select according to independent characteristics: 1.2 0.8 1 1 0.6 0.4 0.2 N2 N3 N4 N5 N6 Time characteristics impact of overcurrent protection TTK 32 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD CHAPTER 7: CHECK THE WORK OF PROTECTION FOR THE SUBJECTS 7.1 Check the work of the transformer protection 7.1.1 Check the work of the transformer protections compare offset current with braking a Checking safety factor in the brake when short circuit in external over current To checksafety factor in the brake when short circuit in external over current, we check when short circuit in enternal over current is the largest - Consider the largest current through short circuit at N2 The largest short circuit current go through protection in every MBA is N (3) short circuit current in the max power system, transformer work independently (3) (3) I N BVmax=I N 2=¿ 12,05 The largest short circuit current go through protection in every transformer is N (1,1) in the max power system, transformer work independently (1,1) (1.1) I N BVmax =I N =12,02 Conclusion, short circuit in external protection by: INngmax = 12,05 I SL=I kcbtt max=f imax K dn K kck I N ngmax ¿ 0,1.1 1,8.12,05=2,17 I H =2 I N ngmax =2.12,05=24,1 Safety factor in the brake is defined by fomula: With IHtt is calculate restrain current Straight line ISL = 1,34 cut characteristic (c) so: K atH = I H 24,1 = = 4,65 > I Htt 5,18 Protecting brake stady, not affected when short circuit outside the protection zone b Short-circuit sensitivity in the protection zone When short-circuited in the protection zone, because of the supply, the I SL difference current is always equal to the I H damping current, so the theoretical relays always work Check the working of the relay we check the sensitivity : 33 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD With: Ikd – starting current in protection To check the sensitivity of the protection, we consider the smallest short-circuit current when a short circuit occurs in the protection zone (at N1’ and N2’) When short circuit at N1’: Following to calculate in chapter 4, The smallest short-circuit current that passes through short circuit protection at N1 'is a two-phase short-circuit when the system power is minimum INmin= 57,74 We have ISL = IH = INmin = 57,74 Straight line IH= 57,74 cut characteristic line (d) Ikd = Sensivity of protection : = 57,74 =7,22 >2 So, protection ensure to cut safely when having short circuit at N1’ When short circuit at N2’ Following to calculate in chapter 4, the smallest short-circuit current passing through short circuit protection at N2 'is a two-phase short-circuit when the minimum system power, two transformer parallel operation INmin= 16,98 We have ISL = IH = INmin = 16,98 Straight line IH= 16,98 cut starting characteristic current line at characteristic segment (c) Ikd = -1,25+0,5IH = 4,56 Sensivity of protection: K N = I SL 16,98 = =3,72>2 I SLtt 4,56 So, protection ensure to cut safely when having short circuit at N2’ 34 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD The impact characteristics of the braking differential protection applied to the MBA 7.1.2 Check the work of over fast cutting current Check sensivity of protection Sensivity of protection is defined by formula: k N= I N I kd with condition Sensivity of protection : (2) kN= I Nmin I N 9,95 = = =2,81>1,5 I kd I kd 3,54 So protection get requirement for sensitive level 7.1.3 Zero sequence in earth fault ( TTK) Check sensivity of protection Sensivity of protection is defined by formula: k N= I N I kd with condition Sensivity of protection : 35 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD kN= I Nmin I (1,1) 11,45 N2 = = =38,17> 1,5 I kd I kdTTK 0,3 So protection get requirement for sensitive level 7.2 Check the work of the protections in the line 7.2.1 The instantaneous overcurrent Check sensivity of protection kN= I Nmin I (1) 6,67 N6 = = =6,95> 1,5 I kd I kd 0,96 So protection get requirement for sensitive level Check sensivity of protection The smallest short circuit currenr TTK go through protecting is short circuit N(1,1)current at N6 in the minimum power system 5,75 Sensivity of protection: kN= I Nmin 5,75 = =49,9> 1,5 I kd 0,12 => So protection get requirement for sensitive level 7.2.2 Maximum current protection Check sensivity of protection Sensivity of protection is defined by formula: k N= I N I kd with condition Sensivity of protection : I Nmin I (2) 6,87 N6 kN= = = =7,16> 1.5 I kd I kd 0,96 => So protection get requirement for sensitive level 7.2.3 Zero sequence in earth fault (TTK) Check sensivity of protection Sensivity of protection is defined by formula: k N= I N I kd with condition The sensitivity of protection : 36 THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD THE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHODTHE.PRINCIPLES.OF.RELAY.PROTECTION.IN.PROTECTIVE.METHOD