Computerisation of Overhead Line Survey and Design

7/28/2019 Computerisation of Overhead Line Survey and Design

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COMPUTE RI SATI ON OF OVERHEA D L I NE SURVEY AND DESI GNI N THE ELECTRI CI AL SUPPLY I ND UST RY

R. J . Pot t er

S out h of Sc ot l and El ec t r i ci t y Boar dMontr o s e Cr es . , Ham l t on ML 3 6L L

ABSTRACT

The appl i c at i on of comput er s t o 33kV and 1 1 kV over headl i n e s u r v eys i n t he So ut h of Sc ot l and El ect r i c i t y B o a r dhas c al l ed f or a r evi ew of our t r a d i t i onal s ur veyi ng

met hods . The Cent r a l and Sout h West Ar ea o f t h e SSEB i sa l a r ge r u r a l one wi t h a c ompl ex net wor k of s ome 9000 kmof over head di s t r i but i on l i nes . The c o ns t a ntmai nt enance, e xt e ns i on and r e i n f o r c e me nt of t he net wor kr e s u l t s i n a ppr o xi mat el y 100 km t o be s u r v e y e d per annum.The t wo o v e r h ead l i ne t ypes a ccount f or appr oxi mat el y 80%o f al l t he i ndus t r y ' s su r veyed ove r head s u ppl y s ys t em.The maj o r r eas on f or t he appl i c at i on of comput er s was t ospeed up t he r o u t e s el ec t i on and des i gn pr oc e s s . Thi swas a c hi e ve d by us i ng di gi t al r ec or ding e qui pment and aut omat i c al l y pr oc es s i ng t he dat a on a c omput er andpl ot t er . Thi s pape r des c r i bes t he met ho ds we used t oac h i e ve t hi s .

DESI GN REQUI REMENT

The des i gn and c o n s t r u c t i on of over head l i nes r equi r esabout 80% c i vi l and 20% el ec t r i c al engi neer i ng. I tr equi r es a t y p e of s u r v e y t h a t has l i t t l e compar i son i nany ot her a ct i v i t y . An opt i m s at i on i s o bt ai ned f r o m t hepr o f i le of pol e hei ght s , pol e pos i t i ons and span l engt hsac c or di ng t o t he t er r a i n i n o r d e r t h a t u p l i f t c ond i t i o n i sa vo i de d and t he s t a t u t o r y c ond u c t o r - t o- gr o und c l ea r a nc emay be ma i nt a i ne d at max i mum oper at i ng t e mpe r a t u r e gi v i ngt he g r e a t e s t s ag.

The des i gn c r i t er i a i s c a t e r e d f or by hav i ng a s t a nda r ds pe c i f i c a t i o n f or each t ype of l i ne t o be c ons t r u c t e d .Thi s r egul at es max i mum s p an l e ngt hs , pol e d i a me t e r s ,s t ayi ng ar r angement s e t c . The p r o f i l e i s r equi r ed t oshow, not onl y t he r i s e and f a l l of t he gr o u n d l i ne, butal s o pos i t i ons wher e s up p o r t s c oul d be e r e c t e d t o t he best

advant age. Obs t r uc t i ons t o t he l i ne r o ut e mus t be shownsuch as t r e e s , bui l di ngs , exi s t i ng l i nes c r o s s i ng t he

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pr oposed r o u t e or pos i t i ons wher e er ec t i ng a pol e woul d bei mpr ac t i c abl e, e. g. , gul l i es , r i ver s , r oads e t c . On t hi sgr ound- l i ne pr of i l e t he s u p p o r t s and conduc t o r c a t e n a r y i spl ot t ed.

F or a c c u r a c y of ver t i c al meas ur ement s t he p r o f i l e i senl a r ged t o a r a t i o of 1: 10 v er t i c al t o hor i z ont a l .

CONVENTI ONALMETHODOF SURVEYI NG

Most over head l i n e s u r v e y s ar e c ar r i ed out ' on- l i ne' , i . e .t he i ns t r u me nt i s s et up on t he r o u t e o f t h e ove r head l i n e( s e e F i g 1 ) , wh i c h e na bl es t he r o u t e l engt hs t o bemeas ur ed by s t a di a s and by ar r angi ng t he s t a t i ons t o f a l lon angl e pos i t i ons , t he angl e of r o u t e dev i a t i on can bemeas ur ed by t he i ns t r ument . Thi s enab l es a ngl e pol e

s t ayi ng ar r angement s t o be i dent i f i ed.Anot her met hod i s t he ' of f - l i ne' s u r v e y whi c h of f er s t headvant age of o ver c o mi ng s i ght i ng ob s t a cl es i n t he l i n e oft he r o u t e , and us ua l l y r equi r es l es s s t a t i ons , but ha s t hedi s a dv a nt a ge t h a t r out e l engt hs ha v e t o be chai ned, ormeas ur ed by t a chome t r y, ( F i g .

DISTANCE" ^B Y S t A O I A .

A N G L E O F DEVIATIONM E A S U R E D B YI N S T R U M E N T.

FIG.l.

A N G L E O FDEVIATION MEASUREDFROM 05. M A P.

r . A .

The booki ng met hod i s us ua l l y t he ' hei ght of c ol l i mat i on'whi ch , wi t h an a v e r a g e of 5 0 l ev el poi nt s per k i l omet r e,i s l abor i ous and l i a b l e t o e r r o r .

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By us i ng a t o t a l s t a t i on i ns t r ume nt , co ns ec ut i ve r out el eng t h s can be c a l c ul a t ed b y t h e i ns t r ument a ut omat i c al l yus i ng t he mor e at t r a c t i ve ' o f f - li ne' met hod.

COMPU TER AI DED SURVEY EQUI PMENT

The i nst r ument u sed at t he SSEB Ce n t r a l and Sout h Wes tSc o t l a nd Ar e a i s t he GEODI METER140 To t a l St a t i onI ns t r ument and t he GEODAT 122 numer i ca l da t a l ogger .

The GEODAT ha s f o ur s t a nda r d pr o gr a ms t o c hos e f r o m t oe na bl e t he s u r v e y o r t o i nput d a t a i n sequence, wi t h t heopt i on of pr ogr ammi ng t he GEODAT t o s ui t hi ms e l f . Wef ound t ha t one of t he s t a n d a r d p r o g r ams was s ui t ab l e f oro u r t y pe of dat a .

T O TA L

F I G . 3 .

SURVEY METHOD AND ACCURACY REQUI RED

Sur veyor s may f i n d t he met hods used at Ha mi l tonunconven t i ona l , but not a l l s u r vey s r equi re t he de gr e e ofa c c u r a cy t h a t mos t c i v i l c o n s t r u c t i on wor k demands . I no r d er t o expl ai n our mod i f i c a t i o n of s t a nda r d s ur vey i ngmet hods , i t s ho ul d be under s t o o d t ha t when a pol e i spl an t e d i n t he gr ound, us ua l l y t o a dept h of 1. 5 - 2 . 0met r e s de pe nda nt on pol e hei ght , t h a t mos t pol e ho l es a r eme cha ni c al l y e xc a v at ed. A t o l er a n c e of + 0. 1M i spr ac t i c al wi t h t he de pt h of t he exc avat i i on bei ngd i f f i c u l t t o de t e r mi ne wi t h a n y g r e a t e r a c c u r ac y . Gr oundl evel s c an be i ndi s t i nc t e . g . , l evel s t ak en a c r o s s ar ec ent l y pl o ughed f i e l d can v a r y by t hi s amoun t de pe ndi n g upon whet her t he t a r g e t i s pl a ce d at t he t op or b o t t o m ofa f ur r ow.

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Pr of i l e s have been s t andar di s e d t h r o u ghout t he i ndus t r y t oa s cal e of 1: 200 ve r t i c a l l y , s o 0. 1M at t h i s s c al e bec omesl i t t l e mor e t h a n a penc i l l i ne, hence no g r e a t e r a c cu r a c yi s r equi r ed. The hor i z ont al sc al e i s 1: 2000.

L i m t i n g t he a c c u r a c y means t hat i nput f i e l d dat a cou l d bes i mpl i f i ed and i t was dec i ded t o di s pens e wi t h t he s t a t i onhei ght measur ement . As t he t a r g e t he i gh t can be s e t a tt he s ame he i ght as t he i ns t r ument and need never v a r y,except f or t he addi t i on o f a s et ext ens i on s ec t i on, t hent he r e du c ed l e ve ls obt ai ned, show a pr of i l e of t he gr ound l i ne, par al l el t o and s t at i on hei ght above t he a c t u algr ound l i ne. The onl y t i me t he s t a t i on hei ght i sr equi r ed, i s when t he he i ght t o an obs t r uc t i on o r ove r h e a d l i n e c r o s s i ng has t o b e mea s ur e d , t hen t he i ns t r ument he i ght i s added t o t he t a r g e t - t o- obs t r uc t i on hei ght . To

over c ome t hi s , an a v e r a g e s t a t i o n he i ght was i nt r o d u c e di n t o t he p r o g r a m of 1. 55M, t h i s r el at es t o a s u r v e y o r1. 78M t a l l but c an eas i l y be al t er ed i f r e q ui r ed.

Of f -l i n e s ur v ey i ng bec omes muc h mor e a t t r ac t i ve wi t h at o t al s t a t i on i ns t r ument as r o u t e l engt hs c an bec al c ul at ed f r o m ac c u r a t e h o r i z o n t a l a ngl es and di s t ance sr e c o r d e d by t h e i ns t r ument .

CONVER S I ON SO F TWARE

A pr ogr amme was wr i t t en i n BASI C f or a ' PET Co mmodo r e'm cr o - c o mpu t e r t o p r e s e n t t he d a t a i n a s t r a i ght f o r wa rdx- y di s pl ay , s ubdi v i di ng t he d a t a i n t o s e c t i ons ofs t r a i ght l engt hs bet ween r o u t e dev i at i on pos i t i ons . Thepr ogr am wi l l c a t e r f or on- l i n e or o f f - l ine s ur v ey s t ak i ngt he i ns t r uc t i on f r om t he i ni t i al ' i nf o. ' l i ne on t he d a t a l ogger . A s ampl e of t he pr i nt - out i s shown i n AppendixA .

A FORTRANp r o gr am was al s o devel oped t o us e t he s ame d a t at o pr oduce a compl e t e p r o f i l e of gr ound l i ne and s u p p o r t s

on a dr um- pl ot t er . Span l engt hs and po l e hei ght s ar eo p t i m s ed, wi t h t he s ur v e y or hav i ng t he opt i on t o s el ec tpol e pos i t i ons . The pr og r a m r ec ogni s e s o bv i ous " no- pol e 1ar e as s uc h a s , r oads , r i v e r s , di t c hes, et c . , but c an bei ns t r u c t ed on ' no- pol e' a r e a s ei t her i n t h e c ode, t he d a t a l og g e r, or by t he c omput er keyboa r d , e . g. wher e r equi r ed by t he l and- owner or f or pl a nni ng c ons i der at i ons .

W t h al l s u r v e y r e adi ngs bei ng t r ans f e r r e d aut o ma t i c al l yt o t h e Geodat , t he s ur v ey or s i nvol vement i s r educ ed t o s i ght i ng t he i ns t r ument , p r e s s i ng a bu t t o n and c odi ng t hel ev el poi nt . The deci s i on a s t o wh e r e t he l evel poi nt i sr equi r ed f a l l s mor e o n t o t he shoul der s of t he t a r get ma n

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because t he l onger r ange of t he i n s t r umen t i s ol a t es hi m f r o m c l os e super v i s i on and nec es s i t at es t he us e ofpor t abl e R/ T uni t s . Ther e i s now an ar gument f ors u r v e y o r and t a r get man t o change pl aces as t her es pons i bi l i t y of code i dent i f i c at i on c an be made i ne i t he r pos i t i on.

SURVEY CODES

At t he s t a r t of a s u r vey, an el ev en f i gur e i nf o r ma ti oncode i s f ed i nt o t he GEODAT d a t a l ogger s t a t i ng, on oro f f - l i n e s u r v e y ; day mont h and y e a r ; d i s t r i c t of s u r v e y ;and j ob numbe r . The surveyor h as t he chance t o moni t ora nd e di t t he d a t a e i t he r dur i n g o r a f t e r t he s u r v e y.

A code s y s t e m was e vo l v ed t o s a t i s f y b ot h da t a out put

r o u t e s as shown i n Appendi x B . Thi s f our f i gur e code i sde c i de d b y t h e su r veyor f r o m hi s knowledge of t he t e r r a i n,r e qu i r e me nt s of t he s pec i f i c at i on, and f r om i nf or mat i ongi ven t o hi m b y t he t a r g et ma n. T he codes gi ve t hes u r v e y o r t he oppor t uni t y t o di ct a t e pol e pos i t i ons ori nc r eas e t he gr o u n d t o conduc t o r c l ear a n c e hei ght , i n t hef i e l d or i n t he of f i c e . Bo un da r i e s ar e no r mal l yp r e f e r r e d pol e pos i t i ons and c an be s up p o r t ed by a f i gur e1 i n t he t h i r d col umn.

Si de- s l ope i n t he f o u r t h co l umn , s aves t he s u r v e y o r t het r oubl e of t ak i ng o f f - s e t l eve l s i n o r d er t o det er m ne t hei nc r eased conduc t o r he i g ht ( F i g . 3 ) . The dr u m pl o t t e rwi l l show t he s i de- s l ope l i n e as a d o t t e d l i n e above t hec e n t r e l i n e o f t h e r o u t e . The amoun t of s i de- s l ope c anbe eas i l y e s t i mat e d b y t he su r veyor us i ng a hand- hel di n c l inomet er .


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When r ea di ng ont o a b ac ks i ght , t he s ame poi nt number i sf ed i n t o t he Geodat and t he p r o g r a m wi l l c al c ul a t e t he newhei ght of c ol l i mat i on, unl es s a f i gur e of 4 , 5 , 6 or 7 i sent er ed i n t he f i r s t col umn i n wh i c h case t he p r o g r a m wi l lexpect t he next r eadi ng t o be a ver t i c al a ngl e i n orde r t of i n d t he h ei ght o f t h e c r os s i ng.

COMPUTER PRI NT- OUT

The pr i nt - out shown i n Appendi x A i s used f or al l non-s t a nda r d o v er h ea d l i nes ( r e - s t r i ngi ng e t c . ) , whi ch have t obe pl ot t ed ma nu al l y, but i t i s pos s i bl e t o us e t he d r u mpl ot t er t o pr oduce t he ground l i n e onl y.

Two pr i nt - out s ar e pr ov i ded by t he d r u m pl ot t er , one i st he compl e t e p r o f i l e as shown i n Appendi x C , and t he o t her

a ma t er i a l l i s t c o mpi l e d f r o m t he p r o f i l e and l i n es pec i f i c at i on dat a. F or c l ar i t y unnec es s a r y i nf or mat i onwas omi t t ed f r o m t he pr o f i l e. Pol e number s , he i ght ofpol es i n met r es , di amet er at 3M f r o m b u t t i n mi l i met r es ,and t y pe of pol e, i . e . , t er m nal , s ec t i on a ngl e ,i nt er medi at e or s t r a i ght l i n e s ec t i on, i s shown above t hepol e. Al l hedges, f enc es , wal l s et c . , ar e shown asb ou nda r i es . A po l e f i xed by t he s u r v e y o r i s mar ke d wi t han ' F ' bel ow t he gr ound l i ne but i f he i s not h app y wi t ht he pl ot t hen he i s abl e t o del et e hi s f i xed pos i t i ons ,r e - r u n t he pl ot wi t h new pos i t i ons or al l ow t he c omput er

t o s el ec t pos i t i ons .He i gh t s of l i nes c r o s s i ng t he p r o p o s e d r o u t e ar e gi v en i na t abl e at t he end o f t h e p r o f i l e as t hes e have t o beadj us t ed f or t he t e mpe r a t u r e o f t h e day and pos i t i on ofi nt er s ec t i on. We f ound t hat i t was s i mpl er t o pl ot t h e s eont o t he p r o f i l e on c ompl e t i o n o f t h e pl ot af t er al l t hees s ent i a l i nf or mat i on had been ga i ne d and t he equi v al enthei ght c al c ul a t ed.

The p r o g r a m wi l l a l ways chose t he s ma l l es t suppor t t o gi v et he r equi r ed c l ear anc e wi t h t he mos t e c ono m c a l spanl engt h. A ma t e r i a l l i s t i s t hen c o mpi l e d f r o m t hec o mpl e t e d pr o f i l e s u mma t i ng al l t he mat er i a l s r equi r ed t oc o n s t r u c t t he l i ne. Thi s i s a nor mal r equ i r ement at t heend of a pr of i l e, howev er t he comput er ou t pu t al l ows t hepr oduc t i on of l i s t s f or wayl eave negot i a t i ons or t r e ef el l i ng s c hedul es e t c .

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CONCLUSI ON

The appl i c at i on of comput er equi pment has r es ul t ed i n amuch qui cke r t u r n o v er of pr o f i l es f t he i nvol vement i n t heDr awi ng Of f i c e has meant t ha t a f ul l day ' s pl ot t i n g t i mei s r e duced t o l i t t l e l es s t han hour a t a work s t at i onand f i e l d wor k has been r educed by 50% on f or merconvent i onal met hods .

ACKNOWL EDGEMENT S

I wi s h t o t h a nk t he SSEB f or al l owing me t o p r e s ent t h i spaper t o t he c onf e r e n c e and a l s o my c ol l eagues f orp r e par i ng s o f t ware and c ar r y i ng out f i e l d t r i a l s .


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APPENDI X' A '

SPECI MEN PRI NT- OUT

OFF L I NE SURVEYDATE 30. 01. 86CENTRE FAL K I RKJ OB NUMBER374SURVEY FI L E NAME HEATHHAL L 1SHEET 1

NO.

1

234456789

1 0

1 11 2

1 31 41 51 51 61 71 71 81 9

12 01 2 112 212 312 412 512 6I

CODE

0 1 0 00 1 000 1 0 0

0 1 0 05 1 0 011 0 02 1 002 1 7 50 3 0 30 3 0 30 76 2

0 7 8 00 6 0 5

11 0 51 20 00 2 0 06 2 0 00 2 0 01 2 0 01 2 0 00 2 0 002 0 00 2 0 002 0 01 3 6 00 3 0 00 1 0 00 1 0 001 0 0

DESCRI PTI ON

PASTUREPASTUREPASTURE

P ASTURE1 1 k V XI NG PAST UREBOUNDARY PASTUREWATER EDGE PASTUREWAT EREDGE PASTURE SLOPE STARTR OUGHS L O P EA DD2 . 6 3 M( 7 . 8 3 )ROUGHSL O P EA DD2 . 6 3M( 7 . 8 3 )TREES ANGLE P OS I T I ONSLOPEADD1 . 4 3 M( 6 . 6 3 )TREESSL OPE ENDSROAD

BOUNDARY PASTUREBOUNDARY ARABLEARABLE33 kV XI NGARABLEARABLEBOUNDARY ARABL EBOUNDARYARABLEARABLEARABLEARABLEARABLEBOUNDARY ROUGH ANGL E POSI TI ONROUGH

. PASTUREPASTUREPASTUREF I XEDPOLE

HEI GHT RE D. L E V.

4 0 . 3 34 1 .0 04 1. 9 4

42 . 8 41 0 .2 M4 3. 2 54 1. 8 34 1 .8 54 3. 3 34 6. 8 7

4 9 . 2 15 1 . 745 2. 9 3

5 2 .7 85 4. 5 35 8. 6 0

9 . 6 M5 6 . 465 9 . 2 15 9 . 2 16 1 . 5 162 . 6 96 6 . 817 0 .1 1

7 2. 0 37 3 . 827 1. 1 86 8. 0 86 1. 7 2

LENGTH

32. 486 8. 3 5

9 8 . 9 31 27 . 4 015 2 . 751 8 4. 8 32 06 . 4 62 46 . 8 3

3 0 5 . 1 01 9 . 4 73 1. 1 3

4 0 . 1 57 8. 1 99 2 .2 9

1 24 . 7 315 6 . 8 41 56 . 8 41 8 9 . 2 12 34 . 5 22 6 8 . 1 0291 . 8 53 52 . 1 5

5 . 8 24 8. 2 0

1 08 . 3 21 52 . 0 1

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A PPENDIX 'C'

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Documents

Computerisation of Overhead Line Survey and Design