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D

s0

1ln( )N.t .xI , kA

0,02878

s ,naêmLFt FR g f

0,628h bN N 1 S10

A

0T

1S , kV / s1 k.xI Z

2

t PA

0,8E U CD , m2S

t pE 2U , kV

O : Point of lightning stroke S0 : Rate of rise at O, kV/µs I0 : Lightning stroke current , kAX :Distance in which a surge with an infinite slope will decay to slope SA at A, mSA : Rate of rise of surge voltage at A, kV/µs   : Reflection coefficient at transformerEt : Peak surge voltage at transformer, kVSf : 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 Ng: Number of stroke per km2 per yearLF: Lifetime of transformer, year FR: Failure rate of transformer, %Nf : Number of lightning surges arriving at A /year, with slope higher SA

T : Wave front time, sk : Corona damping constant, kV.km/s .

2. The improved protection method (J. R. Lucas Method)

I. The previous protection methodsI. The previous protection methods

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g f

0,628h bN N 1 S10

AS

2

ycf

FR (%)N

LF

AAS2.T 0,02878 .Z 1 S .k.X

f0

xN N. e .dx

t PA

0,8E U CD , m2S

t pE 2U , kV

DO : Point of lightning stroke S0 : Rate of rise at O, kV/µs I0 : Lightning stroke current , kAX :Distance in which a surge with an infinite slope will decay to slope SA at A, mSA : Rate of rise of surge voltage at A, kV/µs   : Reflection coefficient at transformerEt : Peak surge voltage at transformer, kVSf : 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 Ng: Number of stroke per km2 per yearLF: Lifetime of transformer, year FR: Failure rate of transformer, %Nf : Number of lightning surges arriving at A /year, with slope higher SA

T : Wave front time, sk : Corona damping constant, kV.km/s .

2. The improved protection method (J. R. Lucas Method)

I. The previous protection methodsI. The previous protection methods

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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 methodsI. The previous protection methods

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1m

3m 3m 3m

LineA B

LineC

Line

3m

T12T

D12D Arrester

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 D1

S.4. Calculate SJ

cJ

mtt tt.

K3 3S S .N 2 d N 2

, kA/s

A, B, C: Line A, B, C.T1,T2 : Transformer T1 and T2

D1: Separate distance between T1 and line, m.D2: Separate distance between T2 and line, m.Ntt: Number of identified lines

II. II. The proposed protection method

d2 =

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Transformer

Arrester

B

2

1

S

md

D

d

d JS.5. Distance : stroke - substation

m1d =

N(MTBF).100

, km

J Jsa a a o1 2 .

2S 2SV V L. V d + d L .

Z Z

S.6. Voltage of ArresterB: insulation equipments.d1: distance between line and arrester , m.D2: distance between arrester and ground, m.S : slope wave, kA/s.MTBF: mean time between failure, yearFR: acceptable failure rate, %N : number of stroke into line, times /100 km/yearKc: corona damping constant , kV.km/s Va: Mức bảo vệ đầu sóng của chống sét van tại 0,5s, kV Z : line impedance, L : Inductance, H.

with:1MTBF FR(%)

The proposed method based on IEEE Std C62.22.2009

II. II. The proposed protection method

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1m

3m 3m 3m

LineA B

LineC

Line

3m

T12T

D12D Arrester

S.7. Determine D1 and D2: D1 = min (D1_T1_Line A ; D1_T1_Line B ; D1_T1_Line C) D2 = min (D2_T2_Line A ; D2_T2_Line B ; D2_T2_Line C)

II. II. The proposed protection method

The proposed protection method based on IEEE Std C62.22.2009

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Shielding Factor

Distance from objects to line (DO = x), m

(Sf)

Object ‘s Height

H = 10m: Sf = 5,013.10 - 7.x3 – 6,051.10-5.x2 – 0,003655.x + 0,4813 H = 14m: Sf = – 6,047.10 - 12.x5 + 1,452.10 - 8.x4 – 3,332.10 - 6.x3 +0,3459.10 - 3.x2 – 0,0247.x + 0,9982

Nonlinear regression technique

Curve Fitting Matlab

Build 16 relationships Sf, H và DO

Sf = SfL + SfRSfL: S.F at left sideSfR: S.F at right side

II. II. The proposed protection method

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The number of stroke into line

g gf fL fR

0,6 0,628h b 28h bN N 1 S N 1 S S10 10

The inductance line which connect to surge arrester

, times/100km/year

- The inductance at line (length 1 m)

7 123o

DL =2.10 .ln

r , H/m

- The inductance line which connect to surge arrester

7 123o1 2 1 2.

DL = d + d L = d + d .2.10 .ln

r , H

Which: 3123 12 23 13D D D D , m

II. II. The proposed protection method

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Check MTBF of transformer

2

a a2 T Ta aJ J T2

2,92.D.V .Z D.V .Z 0,77.L.C.V 1,54.L.V .C5,84.L.D.Z 1,54.C.L S S 0,385.C.V V V 0 ZZ

J

g c f

1000.SMTBF 0,6N .K .(28h b).(1 S )

II. II. The proposed protection method

(1)(3)

Nonlinear regression technique

Curve Fitting Matlab

Build 6 relationships Sf, H và DO

0,9998gMTBF =107,5.N 0,02619

1g MTBF 195,4.N 0,0254 M

TB

F (y

ear)

Ng (times/km2.year)

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1. Introduction of OPSOLA Program

OPSOLA  (Optimal Placement Software Of Lightning Arrester )

III. OPSOLA ProgramIII. OPSOLA Program

Determine optimized arrester’s location

Check MTBF of transformer

Single phase, single transformer

substation

Three-phase, two-transformer

substation

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2. Calculation Interface Main Interface Configuration

III. OPSOLA ProgramIII. OPSOLA Program

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3. Single line, single transformer Substation

III. OPSOLA ProgramIII. OPSOLA Program

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4. Three-line, two-transformer Substation

III. OPSOLA ProgramIII. OPSOLA Program

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5. Checking MTBF

III. OPSOLA ProgramIII. OPSOLA Program

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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. ResultIV. Result

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