Designing 400 kV Transmission Line

Al‐Balqa’ Applied University

 January  2011 n part a

u

ment o t e equ rements or t e egree o

ac e or o

Science in Engineering Technology

Supervisor:

Dr.Ibrahim Abu Dr.Ibrahim  Abu‐Harb repare

y

 Ammar  Amer   Amer  Abu_Khaled   Abu_Khaled   Na’el  Ali  Ali Nofal 

Mohammed K. Mohammed  K. Hawa

CONTENT 

INTODUCTION TO TRANSMISSION SYSTEM.



TRANSMISSION LINES.



ELECTRICAL AND ELECTRICAL  AND MECHANICAL DESGIN OF OHTL.



CALCULATIONS AND CALCULATIONS  AND MATLAB FILES.

INTRODUCTION TO TRANSMISSION

Jordanian Transmission system

•The figure represents the

 Jordanian map with map with the 132kV national 132kV national grid and 00 kV interconnection kV interconnection network.

Jordanian Transmission system

Elements of  of design design • Desi Desig ning ning 400 kV kV sys syste te m s is a d iffic ffic ult ult job b e c a use use the re a re m a ny fa c to rs sho uld uld b e ta ke n in in m ind w he hen n the d esi esig ning ning en eng g ine neer ers s sta rt the . • The hes se fa c to rs d e p end o n the syste yste m sta nd a rd s, ec o no nom m ic a l fund s for the line a nd a va ila b ility o f te c hnic hnic a l and p ro fess fessio na l p e rso ns. ns. •

M o st im im p o rta nt fa c to rs a re :

• . • Typ e o f to w e rs. • T e of o f in su la t o rs rs. • Cl Clea ea ra n c e f a c tor tor.. • Sa g a nd tens tensiio n.

n or an ere s a rap grow n oa s a a e coun ry w c orce e electrical transmission company (NEPCO) to construct new lines to feed that loads with the th e electrical power.

shows the peak load development in Jordan

e gure e ow s ows e percen age o power genera on or a power p an s In the Jordanian Electrical system

Single and Double circuits for 400 kV

Single Circuit

Double Circuit

Structures ma have one of the three basic confi urations: horizontal vertical or  delta, depending depending on on the arrangement of the phase conductors.

Fig (2‐1) Lattice towers

The main types types of towers are are used in designing designing transmissio transmission n lines:

•SUSPENSION TOWER: Most of transmission lines towers are of this type (about 80%)

•TENSION TOWERS: This type of towers is used to carry power powe r lines, Two Two main types are a re used: • º. •Tension •Tension towers with wi th large angles (less than 65º).

•TERMINAL TOWERS: Starting and end lines towers are the two types of terminal transmission lines towers, s a ens ens on ower  ower 

•CROSSING TOWERS: Usually this type is used for crossing rivers, valleys and wide high ways.

OVERHEAD

ACSR is the most common type o con uctor use to ay

2) AA AAC C {All {All Al Alum umin inum um Con Condu duct ctor ors} s}::

electrical loads are heavy and where spans are short and mechanical loads are ow so are are use or   power distribution.

BUNDLE CONDUCTORS

Two conductor/phase

Four conductor/phase

Earth Wire 

A ground conductor is a conductor that is usually grounded (earthed) at the top of the supporting structure to minimize the likelihood of direct lightning .



The ground wire is also a parallel path with the earth for fault currents in eart arthed neutral circu rcuits, Very high-voltage transmission lines may have two ground ground conduc conductors tors..



The ground conductors not only used to protect the lines from the lightning strikes but also contain a fiber optic, used for communications and remote control of ower s stem 

The ground wire that tha t used in 400kV transmission system is .

OPGW has OPGW  has three main types 1) Stainless steel loose tube type OPGW.

2) N 2) Nonon-metallic -metallic loose tube type OPGW.

3 Aluminum s acer t

e OPGW.

Types of  of insulators insulators 1) Tension insulators: usually they are usually they  are used used when  when t e span s more t an 3 0m

2) Suspension insulators: usually they are used if the span between tower is 360 m or less, and with heavy conductors.

3) Ground Wire Insulators overhead ground ground wires on the high-voltage transmission lines lines..

 A) Porcelain. has a mechanical strength and a high electrical insulation its demerit that it is hard to detect the damage on it.

B

Tou oug g en ene e G ass Insu ators.

•It Has a high electrical electrical insulation as porcelain porcelain insulators •Its •Its ad adva vant nta a e tha thatt itit doe does s not not affe affect cted ed b the the the therm rmal al stresses, • it is susceptible susceptible to to breakage breakage and more expensi expensive ve than porcelain

C) Polymer Insulators •It has a light weight and it still very long time without polluting with dust. •But it may be damaged by corona effect, or physical deterioration which may not be apparent.

ELECTRICAL  AND MECHANICAL

Electrical parameters

Mechanical parameters

Electrical parameters

Line

Line

Line Ca acit acitan ancce

Conductor resistance is affected by these by these factors:‐  ‘ ’  Temperature  The material of conductor of  conductor The direct current resistance of  of aa conductor is given by: 

ρ: Conductor resistivity, Ω.m

R  DC 

A

Ω

L : Conductor length, m.  A :: Cross sectional of conductor  A  of  conductor area, m2.

e a ternat ng current res stance o a con uc ucttor s g ven  y: R 

 R 

( 1   y

 y )

Ys : skin effect factor 

The conductor resistance increases as temperature increases. increases. As  As in this equation: 2

R 1



TO  t T O  t1

n uc an ance o

ou e c rcu o

ree p ase ne

We us use the the foll follow owiin e uati uation onss to to fin find d the the GMD between each phase group

 D AB  4  D a1b1 D a1b 2 D a 2 b1 D a 2 b 2



4

 D AC   4  D a1c1 D a1c 2 D a 2 c1 D a 2 c 2

The equivalent GMD per phase is

GMD  Deg  3 ( D AB * D BC  * D AC  ) Double circuit configuration

The equivalent GMR per GMR per phase is  D

SA

SB

 D

 

4

(  D

 b S 

 D

4

4

 D

 b

)

2

2

 D



 D



b1b 2

S 



a1 a 2



b S 

D

S 

 D

b S 

a1a 2

b1b 2

 D

 D b

b s

, and Ds is the GMR of  GMR of the the individual conductors.

The inductance per-phase is  L  x  2  10

 7

ln

GMD

 H  / m  L

.

*

Capacitance of  of double double circuit of  of three three phase line The GMRc of each of  each phase is similar to the GMR L, with the exception that (rb)is used instead of (D of  (Ds b ). This will result the following equations: b  A

a 1 a 2

r 



r   D

r C 



r 

GMRC   3 r  r   B r  C 

b

b

D

c 1 c 2

The per‐phase equivalent capacitance to neutral is obtained by: 2  

C   n

0

GMR

 F  / m c

The e ui uiv val alen entt circuit of  of short short transmission line

‐ ‐ 

S 



 R

–

We can re resen esentt the line con onst stan ants ts as matrix:

V  s   I  s 



 A  B  V r  C   D   I r  

A=D= 1 B= Zline C= 0



line  R S 

 R

CORONA DETERMINATION actors ect on orona:   Atmosphere  Atmosphere  Con uct uctor size  Spacing between conductors  Line vo Line voltage ltage

Dielectric st strren th depends on:  

t e atm tmo osp er c temperature . The atmospheric pressure.

  



3 . 92 b

W ere:  b: Atmospheric pressure pressure (mm Hg). Hg). 0 .

Critical Corona Corona V  Voltag oltages es .

It is the minimum phase vo phase voltag ltagee at which at which corona occurs:

Dequ VC  mo .  .r.ln( ) B. Visua isuall Crit Critic ical al Volta olta e

The visual critical voltage V v for single &three phase lines be obtained:

VV 



4

2

r 

mv 1 

 

  * r  

Where r  r is is the conductor radius in meter  m v  is the (irregularity factor). e owes s ance e ween con uc ors. equ:

n

d  r 

Mechanical Parameters TOWERS HEIGHT

LINE SPAN

CONDUCTOR 

TENSION

 AND SPACING CONDUCTOR   VIBRATION

Span definitions Basic or normal span :



The normal normal s an is the most economi economical cal span for which which the line is designed designed ove overr level level ground ground .



•

The average span is the mean span length between dead ends.

Dead End Span :



• A dead end span is the one in which the conductor is dead ‐ended

.

Wind Span :



e w n span s t at at on w c t e w n s assume to act transversely on the conductors and is taken as half the sum of two spans. •



Weight span •The weight span is the horizontal

dist distan ancce betw betwee een n the the low lowest est poin points ts of  . 

Ruling or equivalent span • It is the w the weight eighted ed average of  the varying the varying span lengths.

l   l   l   l  ...... l  3 1

r 

3 2

3 3

3 4

l 1  l 2  l 3  l 4 .... l n

3 n

Sag calculation Sag is defined as: the increment in length of overhead of  overhead lines that suspended between two points, and there are two cases.

ymmetr ca suspens on eve :  when the two supports are at the same level.

1

S 

2

w*l 

ere: S: sag at the middle of span of  span (m)  w:: conductor’s weig  w conductor’s weight ht (N/m) l: horizontal distance of span of  span (m) T: conductor tension (N)

 When the two supports are at different level

  Aeolian  Aeolian Vibration:  Vibration:

It is a high‐frequency ( frequency (5-100 Hz) low amplitude (2.5-5 cm) osci osci atio ation n generate  y  ow ve ow ve ocity  0.5-10 m/sec .  Galloping Galloping Vibration:  Vibration:

It is a low frequency ( frequency (0.1-1Hz) high amplitude (several meters se excite  vi ration w ration w ic can a ect sing e an bundle conductors.

acco accord rding ing to standar standards ds.. An empirical formula commonly used for  determining the spacing of aluminum conductor lines is :

Spacing =

d  

 And here some t

V 

meters

 Where: d: is sag in meters

ical values of s of  s acin are:

TOWERS HEIGHT The overall height of the tower is:

H = C + So + 3*SA + SB + SC+ SE

Where : statutory ory c eara earance nce to to groun groun •C = statut •SA = length of suspension insulator set •SB, SC and SE = vertical distances between cross-arms and conductor above or to earthwire cond nduc ucto torr ro or orti tion onal al to th thee •So = sa of co square of the span).

400

‐

LINE CALCULATIONS

CALCULATIONS

ELECTRICAL LINE’S

MECHANICAL LINE’S

ELCTRICAL PARAMETERS

LINE RESISTANCE

 AND INDUCTANCE

 VOLT  VOLTAGE

EFFICIENCY 

Choic of volta l v l &Circ its configuration  value of power power taken from NEPCO NEPCO 600 MW so the suitable  value:

Selecting the number of circuits of  circuits depends on the SIL(surge im edan edancce loadin The characteristic impedance = 320

es stance ca cu at on  ACSR 560/50  ACSR 560/50 conductor is used in the line with line with a R DC =0.0514 ohm at 20 °C

The resistance of  A of   ACSR  CSR at at a tem tem eratu erature re rise 65oC is :

line inductance and capacitance Line inductance and capacitance are measured by using the GMD method for the  bundled conductor 

GMD method calculation

Tower spacing (in mm)



The GMD and GMR  values GMR   values can be found to calculate

The Receiving end voltag end voltage e line to line is:

Vr   230.940 kV  

 Z line  5.804272.3069Ω The im edan edancce of line of  line er‐ hase is: The receiving ‐end and sending end current:  I r   I  s  1345.06  25.84 A

The Th e sendin end volta end volta e line to line is: The sending end active power is:

.

.

 Ps  848.2934MW 



Volt lta a e re ul ula ati tion on and line efficienc Voltage oltage regulati regulation on :

.

Double circuits eff.

Corona effect calculation Corona starting voltag starting voltagee : according to the equation shown previously the previously  the corona starting voltag starting voltagee equal

Visual critical voltage :for polished conductor will equal

Total corona losses :found by using by using an empirical formula

MECHANICAL CALCULATIONS

SPAN

SAG

TOWER 

Conductor used in the line (SAMRA-AMMAN (SA MRA-AMMAN NORTH) is ACSR 560/50 mm, with cross section diameter = 26.7 mm. As the spans between the line towers not equal the ruling(equ ruling(equivalen ivalent) t) span is found

By taking By taking an example of two of  two towers sag at symmetrical spacing the value the value

The maximum sag of conductor at bad weather  (15m/s wind velocity and ice thickness about 10mm)

:

Tower height H = C + So + 3*SA + SB + SC + SE nsu ator str ng engt = mm Sag = 3380 mm

Insulator-arm distance ={2470,2635,1985} mm from upper to lower  Maximum clearance= 15000mm .

.

.

.

.

=45.015 m c ose o

e ower e g

rom

m

CHAPTER FIVE

MATLAB M‐FILE By using By using MATLAB all values all values calculated in the project wer project weree found in a program that Designed for any line any line –not only this only this line‐. 1) At 1)  At first step the line power, vo power, voltag ltagee and power factor at the receivin side will: side will:

2) The outputs of the program will shown like below

rcu t con gurat on w

e se ecte to n t e ne n uctance an capac tance

5) Then Matlab calculate the value of GMD and GMR 

6) The output of the program at the final step is

By comparing By comparing the results that we that we calculated and that ones from MATLAB, the ..

230.5 kV

2.13