1. FEEE Ensuring Enhanced Education 1 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

2. FEEE Ensuring Enhanced Education 2 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

3. FEEE Ensuring Enhanced Education 3 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

4. FEEE Ensuring Enhanced Education 4 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 =

5. FEEE Ensuring Enhanced Education 5 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

6. FEEE Ensuring Enhanced Education 6 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

7. FEEE Ensuring Enhanced Education 7 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

8. FEEE Ensuring Enhanced Education 8 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

9. FEEE Ensuring Enhanced Education 9 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)

10. FEEE Ensuring Enhanced Education 10 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

11. FEEE Ensuring Enhanced Education 11 2. Calculation Interface Main InterfaceConfiguration III. OPSOLA Program

12. FEEE Ensuring Enhanced Education 12 3. Single line, single transformer Substation III. OPSOLA Program

13. FEEE Ensuring Enhanced Education 13 4. Three-line, two-transformer Substation III. OPSOLA Program

14. FEEE Ensuring Enhanced Education 14 5. Checking MTBF III. OPSOLA Program

15. FEEE Ensuring Enhanced Education 15  Propose the improve method to locate the optimal position of surge arrester with different configuration of substations  Propose the method to determine the Mean Time Between Failure (MTBF) of substation with one transformer and to make sure that the life of transformer according to specified requirement  Construct 16 relationship characteristics between shielding object height, distance from the line to shielding object and shielding factor of distribution line and 6 relationship characteristics between MTBF, shielding factor and areas ground flash density  Build the OPSOLA program to help the users easily determine the reasonable distance and check MTBF of substation IV. Result

16. FEEE Ensuring Enhanced Education 16