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

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

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 C  Influence elements (can be calculated)  Mean Time Between Failure (MTBF ) of Transformer I. The previous protection methods

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 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 C 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 =

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 C II. II. The proposed protection method

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 C

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, x 3 – 6, x 2 – 0, x + 0,4813 H = 14m: S f = – 6, x 5 + 1, x 4 – 3, x 3 +0, 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

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

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)

FEEE Ensuring Enhanced Education 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

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

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

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

FEEE Ensuring Enhanced Education Checking MTBF III. OPSOLA Program

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

FEEE Ensuring Enhanced Education 16