1. FEEE Ensuring Enhanced Education UnUn kV17,52436 BILkV95125170 UpUp kV57,279,9117,6 1 1.The simple protection method The maximum distance: Table 1. BIL and U p (Với: D = a + b) a : The maximum separation between J and pole- mounted transformer, m b : Distance between J and surge arrester, m U t : Arrester residual voltage, kV C: Velocity of wave propagation, C = 300 m/  s. BIL: Basic Insulation Level of Transformer (KV) I. The previous protection methods

2. FEEE Ensuring Enhanced Education 2 2. The improved protection method (J. R. Lucas Method) D O : Point of lightning stroke S 0 : Rate of rise at O, kV/µs I 0 : Lightning stroke current, kA X :Distance in which a surge with an infinite slope will decay to slope S A at A, m S A : Rate of rise of surge voltage at A, kV/µs  : Reflection coefficient at transformer E t : Peak surge voltage at transformer, kV S f : Shielding factor (0,3 ÷ 0,5) N : The number of direct stroke into line, times/100km/year h : Height of nearby objects, m b : Horizontal span between outermost conductors, m N g : Number of stroke per km 2 per year LF: Lifetime of transformer, year FR: Failure rate of transformer, % N f : Number of lightning surges arriving at A /year, with slope higher S A T : Wave front time,  s k : Corona damping constant, kV.km/  s. I. The previous protection methods

3. FEEE Ensuring Enhanced Education 3 D O : Point of lightning stroke S 0 : Rate of rise at O, kV/µs I 0 : Lightning stroke current, kA X :Distance in which a surge with an infinite slope will decay to slope S A at A, m S A : Rate of rise of surge voltage at A, kV/µs  : Reflection coefficient at transformer E t : Peak surge voltage at transformer, kV S f : Shielding factor (0,3 ÷ 0,5) N : The number of direct stroke into line, times/100km/year h : Height of nearby objects, m b : Horizontal span between outermost conductors, m N g : Number of stroke per km 2 per year LF: Lifetime of transformer, year FR: Failure rate of transformer, % N f : Number of lightning surges arriving at A /year, with slope higher S A T : Wave front time,  s k : Corona damping constant, kV.km/  s. 2. The improved protection method (J. R. Lucas Method) I. The previous protection methods

4. FEEE Ensuring Enhanced Education 4 D O : Point of lightning stroke S 0 : Rate of rise at O, kV/µs I 0 : Lightning stroke current, kA X :Distance in which a surge with an infinite slope will decay to slope S A at A, m S A : Rate of rise of surge voltage at A, kV/µs  : Reflection coefficient at transformer E t : Peak surge voltage at transformer, kV S f : Shielding factor (0,3 ÷ 0,5) N : The number of direct stroke into line, times/100km/year h : Height of nearby objects, m b : Horizontal span between outermost conductors, m N g : Number of stroke per km 2 per year LF: Lifetime of transformer, year FR: Failure rate of transformer, % N f : Number of lightning surges arriving at A /year, with slope higher S A T : Wave front time,  s k : Corona damping constant, kV.km/  s. 2. The improved protection method (J. R. Lucas Method) I. The previous protection methods

5. FEEE Ensuring Enhanced Education 5 The previous methods: Accounting for influence elements with some experiment parameters Just considered to single transformer substation The proposed method: Determining surge arrester‘s location for 3-line, 2-transfomer substation based on:  IEEE Std C62.22.2009  Influence elements (can be calculated)  Mean Time Between Failure (MTBF ) of Transformer I. The previous protection methods

6. FEEE Ensuring Enhanced Education 6 S.1. Eliminate 1 transformer and determine the line which the lightning wave transmitted into. S.2. Define the following parameters: - J, the common point between transformer, surge arrester and the line identified in step 01. - D1, distance from J to pole-mounted transformer - D2, distance from arrester to ground (3-line, 2 - transformer substation) The proposed protection method based on IEEE Std C62.22.2009 S.3. Eliminate all line connected to D 1 S.4. Calculate SJ, kA/  s A, B, C: Line A, B, C. T 1,T 2 : Transformer T 1 and T 2 D 1 : Separate distance between T 1 and line, m. D 2 : Separate distance between T 2 and line, m. N tt : Number of identified lines II. II. The proposed protection method d 2 =

7. FEEE Ensuring Enhanced Education 7 S.5. Distance : stroke - substation, km S.6. Voltage of Arrester B: insulation equipments. d 1 : distance between line and arrester, m. D 2 : distance between arrester and ground, m. S : slope wave, kA/  s. MTBF: mean time between failure, year FR: acceptable failure rate, % N : number of stroke into line, times /100 km/year K c : corona damping constant, kV.km/  s V a : Mức bảo vệ đầu sóng của chống sét van tại 0,5  s, kV Z : line impedance,  L : Inductance,  H. with: The proposed method based on IEEE Std C62.22.2009 II. II. The proposed protection method

8. FEEE Ensuring Enhanced Education 8 S.7. Determine D 1 and D 2 : D 1 = min (D 1 _T 1 _Line A ; D 1 _T 1 _Line B ; D 1 _T 1 _Line C) D 2 = min (D 2 _T 2 _Line A ; D 2 _T 2 _Line B ; D 2 _T 2 _Line C) II. II. The proposed protection method The proposed protection method based on IEEE Std C62.22.2009

9. FEEE Ensuring Enhanced Education 9 Shielding Factor Distance from objects to line (DO = x), m (S f ) Object ‘s Height H = 10m: S f = 5,013.10 - 7.x 3 – 6,051.10 -5.x 2 – 0,003655.x + 0,4813 H = 14m: S f = – 6,047.10 - 12.x 5 + 1,452.10 - 8.x 4 – 3,332.10 - 6.x 3 +0,3459.10 - 3.x 2 – 0,0247.x + 0,9982 Nonlinear regression technique Curve Fitting Matlab Build 16 relationships S f, H và DO S f = S fL + S fR S fL : S.F at left side S fR : S.F at right side II. II. The proposed protection method

10. FEEE Ensuring Enhanced Education 10 The number of stroke into line The inductance line which connect to surge arrester, times/100km/year - The inductance at line (length 1 m),  H/m - The inductance line which connect to surge arrester,  H Which:, m II. II. The proposed protection method

11. FEEE Ensuring Enhanced Education 11 Check MTBF of transformer II. II. The proposed protection method (1) (3) Nonlinear regression technique Curve Fitting Matlab Build 6 relationships S f, H và DO MTBF (year) N g (times/km 2.year)

12. FEEE Ensuring Enhanced Education 12 1. Introduction of OPSOLA Program OPSOLA (Optimal Placement Software Of Lightning Arrester ) III. OPSOLA Program Determine optimized arrester’s location Check MTBF of transformer Single phase, single transformer substation Three-phase, two-transformer substation

13. FEEE Ensuring Enhanced Education 13 2. Calculation Interface Main InterfaceConfiguration III. OPSOLA Program

14. FEEE Ensuring Enhanced Education 14 3. Single line, single transformer Substation III. OPSOLA Program

15. FEEE Ensuring Enhanced Education 15 4. Three-line, two-transformer Substation III. OPSOLA Program