Iec tr 60919 2 2015

The tec nical c ntent is identical to the ba e edition and its amen ment.. In this Redl ne version, a vertical l ne in the margin sh ws where the tec nical c ntent is mo if ied b amendme

Performa c of high- v olt age direct c r ent (HV DC) sy t ems w it h l

ne-commut at ed conv rters –

Part 2: Fa lt s and sw it ching

Fonct ionnement des sy t èmes à coura t cont inu haut e t ension (CCHT) munis

de conv rt iss urs commut és par le rés a –

Part ie 2: Défaut s et manoe vre

Co yr ig t © 2 15 IEC, Geneva, Switz r lan

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Performance of high- v olt age dire t cur e t (HVDC) sy t ems w it h l n

e-commut at ed converters –

Part 2: Fault s a d swit ching

Fonc onnement des sy t ème à courant cont inu ha t e t ension (CCHT) munis

de conv rt is e rs commut és par le ré e u –

Part ie 2: Défaut s et ma oeuvres

INT ERNAT IONAL

ELECT ROT ECH ICAL

C MMIS ION

C MMIS ION

INT ERNAT IONALE

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Aten o ! V eui e v us a surer q e v us ave o t en cete p blcatio via u distrib teur agré

Edition 2.1 2 15-0

Performa c of high- v olt age direct c r ent (HV DC) sy t ems w it h l

ne-commut at ed conv rters –

Part 2: Fa lt s and sw it ching

Fonct ionnement des sy t èmes à coura t cont inu haut e t ension (CCHT) munis

de conv rt iss urs commut és par le rés a –

Part ie 2: Défaut s et manoe vre

2

Normativ refere c s 9

3 Outln of HVDC tra sie t p rforma c s e if i atio s 9

3.1 Tra sie t p rforma c s e ific tio s 9

3.2 Ge eral c mme t 10 4 Switc in tra sie ts with ut fa lts 10 4.1 Ge eral 10 4.2 En rgiz tio a d d -e ergiz tio of a.c sid e uipme t 10 4.3 L a reje tio 12 4.4 Start u a d s ut d wn of c n erter u its 13 4.5 Op ratio of d.c bre k rs a d d.c switc e 13 5 AC s stem fa lts 15 5.1 Ge eral 15 5.2 Fa lt c te orie 16 5.3 Sp cific tio maters af fe tin tra sie t p rforma c 16 5.3.1 Eff ectiv a.c s stem imp d n e 16 5.3.2 Power tra sfer d rin f aults 16 5.3.3 Re o ery folowin fa lt cle rin 17 5.3.4 Re ctiv p wer c n umptio d rin fa lt a d p st fa lt re o ery p rio s 18 5.3.5 L a reje tio d e to a.c f aults 18 5.3.6 Switc in of re ctiv p wer e uipme t 19 5.3.7 Eff ects of h rmo ic v lta e a d c re t d rin f aults 19 5.3.8 Shif in c ntrol mo e of o eratio 19 5.3.9 Power mo ulatio o th HVDC s stem 2

5.3.10 Emerg n y p wer re u tio s 2

5.4 Sp cific tio imp ct o c ntrol strate y 2

6 AC f ilters, re ctiv p wer e uipme t a d a.c b s f aults 2

6.1 Ge eral 2

6.2 Tra sie t o erv lta e in fiter b n s 2

6.3 Tra sie t o erc r e ts in fiter a d c p citor b n s 2

6.4 Ca a itor u b la c prote tio 2

6.5 Ex mple of prote tio of f ilters a d c p citor b n s 2

6.6 Sh nt re ctor prote tio 2

6.7 AC b s prote tio 2

7 Co v rter u it f aults 2

7.1 Ge eral 2

7.2 Sh rt circ its 2

7.3 Faiure of c n erter u it to p rf orm its inte d d fu ctio 2

7.3.1 Ge eral 2

7.3.2 Re tifier o eratio 2

7.3.3 In erter o eratio 2

7.4 Co v rter u it prote tio 3

7.4.1 Co v rter dif fere tial prote tio 3

7.4.8 Tra sformer ta -c a g r u b la c prote tio 31

7.4.9 AC c n e tio e rth fa lt prote tio 31

7.5 Ad itio al prote tio a p cts of s rie c n e te c n erter u its 31

7.6 Ad itio al prote tio a p cts of p ralel c n e te c n erter u its 31

8 DC re ctor, d.c fi ter a d oth r d.c e uipme t fa lts 3

8.1 Ge eral 3

8.2 Fa lt ty e 3

8.3 Prote tio z n s 3

8.4 Ne tral prote tio 3

8.4.1 Ge eral 3

8.4.2 Ne tral fa lt d te tio 3

8.4.3 Ne tral b s fa lt is latio 3

8.4.4 Bip lar n utral b s f aults 3

8.5 DC re ctor prote tio 3

8.6 DC h rmo ic fiter prote tio 3

8.6.1 Ge eral 3

8.6.2 Fiter b n fa lt prote tio 3

8.6.3 DC fi ter c p citor u it prote tio 3

8.7 DC h rmo ic prote tio 3

8.8 DC o erv lta e prote tio 3

8.9 DC sid switc in prote tio 3

9 DC l n f aults 3

9.1 Ov rh a ln fa lts 3

9.2 Ca le fa lts 4

9.3 DC fa lt c ara teristic 4

9.4 Fu ctio al d.c fa lt d te tio re uireme ts 41

9.5 Prote tiv s q e c 41

9.5.1 Ov rh a l n f aults 41

9.5.2 Fa lts in c ble s stems 41

9.5.3 Fa lts in a o erh a l n /c ble s stem 41

9.5.4 Fa lts in o e of a s stem of p ral el-c n e te c ble 41

9.5.5 Fa lt in a s stem of p ral el o erh a l n s 4

9.6 Fa lt prote tio s h me 4

9.7 Op n circ it o th d.c sid 4

9.8 Power ln cro s prote tio 4

10 Earth ele tro e l n fa lts 4

10.1 Ge eral 4

10.2 Sp cific re uireme ts – Earth ele tro e ln 4

10.3 Ele tro e ln s p rvisio 4

1 Metal c return c n u tor fa lts 4

1 1 Co d ctor f or th return circ it 4

1 2 Metal c return f aults 4

12.4 Switc in o erv lta e a d temp rary o erv lta e o th d.c sid 4

12.5 Lig tnin a d ste p fro te s rg s 4

12.6 Prote tiv margin 5

12.7 Ar e ter d tie 51

12.7.1 AC b s are ters (A 1 , A 2 a d A 3 ) 51

12.7.2 Ar e ter a ro s fiter re ctors (FA) 51

12.7.3 Valv ar e ters (V) 5

12.7.4 Mid-p int d.c b s ar e ter (M) 5

12.7.5 Co v rter u it d.c b s ar e ters (CB) a d c n erter u it ar e ters 5

12.7.6 DC b s a d d.c ln ar e ters (DB a d DL) 5

12.7.7 Ne tral b s are ters (E 1 a d E 2 ) 5

12.7.8 DC re ctor ar e ter (R) 5

12.7.9 DC fi ter ar e ters (FD) 5

12.8 Pre e tio of prote tiv rela a tio d e to ar e ter c r e ts 5

12.9 In ulatio cle ra c s 5

12.10Cre p g dista c s for th in ulatio 5

12.10.1 Outd or in ulatio 5

12.10.2 In o r in ulatio 5

13 Tele ommu ic tio re uireme ts 5

13.1 Ge eral 5

13.2 Sp cific re uireme ts - Tele ommu ic tio s stems 5

13.3 Co s q e c of tele ommu ic tio s stem o ta e 5

13.4 Sp cial c n id ratio s f or p wer l n c r ier (PLC) s stems 5

14 Au i ary s stems 5

14.1 Ge eral 5

14.2 Ele tric l a xi ary s stems 5

14.2.1 Ge eral re uireme ts 5

14.2.2 Sp cific re uireme ts 6

14.3 Me h nic l a xi ary s stems 6

Bibl o ra h 6

Fig re 1 – DC-sid switc e f or a HVDC s b tatio with s rie -c n e te c n erter u it 15 Fig re 2 – Ex mple of v lta e d p n e t c ntrol c ara teristic 21

Fig re 3 – Ex mple of ar a g me t of a.c fiters a d c p citor a d re ctor b n s for larg bip lar HVDC 2

Fig re 4 – Ex mple of c r e t tra sformer ar a g me ts f or a.c f ilters a d a.c b s dif fere tial prote tio s 2

Fig re 5 – Ex mple of re tricte gro n fa lt prote tio of fiter 2

Fig re 6 – Ex mple of c r e t tra sformers ar a g me t f or c p citor b n u b la c prote tio a d o erlo d prote tio of d u le tu e fiter arm 2

Fig re 7 – Ex mple of a.c p a e s ort circ its, p le s ort circ its a d f aults in a twelv -p ls c n erter u it 3

Fig re 12 – Mo o olar metal c return s stem s owin metal c return tra sfer bre k r

(MRTB) 4

Fig re 13 – Mo o olar o eratio of a bip lar s stem d rin c n erter p le o ta e 4

Fig re 14 – DC c r e t flowin into a a.c s stem d rin a fa lt o a metal c return

c n u tor wh n th HVDC s b tatio mat is u e for gro n in of th d.c circ it 4

Part 2: Faults and switching

1) Th Intern tio al Ele trote h ic l Commis io (IEC) is a worldwid org nizatio for sta d rdizatio c mprisin

al n tio al ele trote h ic l c mmite s (IEC Natio al Commite s) Th o je t of IEC is to promote

intern tio al c -o eratio o al q estio s c n ernin sta d rdizatio in th ele tric l a d ele tro ic fields To

this e d a d in a ditio to oth r a tivities, IEC p blsh s Intern tio al Sta d rds, Te h ic l Sp cif i atio s,

Te h ic l Re orts, Pu lcly Av ia le Sp cif i atio s (PAS) a d Guid s (h re fter ref ere to as “IEC

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in th su je t d alt with ma p rticip te in this pre aratory work Intern tio al g v rnme tal a d n

n-g v rnme tal org nizatio s laisin with th IEC also p rticip te in this pre aratio IEC c la orates closely

with th Intern tio al Org nizatio for Sta d rdizatio (ISO) in a c rd n e with c n itio s d termin d b

a re me t b twe n th two org nizatio s

2) Th formal d cisio s or a re me ts of IEC o te h ic l materse pres , as n arly asp s ible,a intern tio al

c nse sus of o inio o th rele a t su je ts sin e e c te h ic l c mmite h s re rese tatio f rom al

intereste IEC Natio alCommite s

3) IEC Pu lc tio s h v th f orm of e omme d tio s f or intern tio al use a d are a c pte b IEC Natio al

Commite s in th t se se Whie al re so a le ef forts are ma e to e sure th t th te h ic l c nte t of IEC

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misinterpretatio b a y e d user

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th later

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servic s c rie o t b in e e d nt c rtific tio b dies

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Pu lc tio s

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p te t rig ts IEC sh l n t b h ld resp nsible f or id ntifyin a y or al su h p te t rig ts

DISCLAIMER

This Consol dated versio is n t an of f icial IEC Standard an ha be n prepared f or

us r c nvenien e Only the c r ent versions of the stan ard an its amendment(s)

are to be c nsidered the of f icial d c ments

T is Consol dated versio of IEC TR 6 919-2 be rs the editio number 2.1 It c nsists

amen ment 1 (2 15-0 ) [d c ments 2 F/34 /DTR an 2 F/345A/RVC] The tec nical

c ntent is identical to the ba e edition and its amen ment

In this Redl ne version, a vertical l ne in the margin sh ws where the tec nical c ntent

is mo if ied b amendment 1 Additio s and deletio s are displayed in red, with

deletions bein stru k throu h A s parate Final versio with al c an e ac epted is

avai able in this pu l cation

IEC 6 919-2, whic is a te h ic l re ort, h s b e pre are b s b ommite 2 F: Power

ele tro ic f or ele tric l tra smis io a d distrib tio s stems, of IEC te h ic l c mmite 2 :

Power ele tro ic s stems a d e uipme t

This e itio in lu e th f olowin main c a g s with re p ct to th pre io s e itio :

a) this re ort c n ern o ly ln -c mmutate c n erters;

b) sig if i a t c a g s h v b e ma e to th c ntrol s stem te h olo y;

c) s me e viro me tal c n traints, f or e ample a dible n is lmits, h v b e a d d;

d) th c p citor c u le c n erters (CCC) a d c ntrole s rie c p citor c n erters (CSCC)

IMPORTANT – T e 'c lo r inside' log o the c ver page of this p bl catio in icate

that it c ntains c lours whic are c nsidered to be us f ul f or the c r ect

u derstan in of its c ntents Us rs sh uld therefore print this d c ment usin a

c lo r printer

1 Scope

This p rt of IEC 6 919 whic is a te h ic l re ort pro id s g id n e o th tra sie t

p rforma c a d f ault prote tio re uireme ts of hig v lta e dire t c r e t (HVDC) s stems

It c n ern th tra sie t p rf orma c relate to fa lts a d switc in f or two- ermin l HVDC

s stems uti zin 12-p ls c n erter u its c mpris d of thre -p a e brid e (d u le wa )

c n e tio s b t it d e n t c v r multi- ermin l HVDC tra smis io s stems Howe er,

c rtain a p cts of p ral el c n erters a d p ral el ln s, if p rt of a two- ermin l s stem， are

dis u s d Th c n erters are a s me to u e th ristor v lv s a th brid e arms, with

g ple s metal o id ar e ters for in ulatio c -ordin tio a d to h v p wer flow c p bi ty in

b th dire tio s Dio e v lv s are n t c n id re in this re ort

Only l n -c mmutate c n erters are c v re in this re ort, whic in lu e c p citor

c mmutate c n erter circ it c n g ratio s Ge eral re uireme ts for s mic n u tor ln

-c mmutate c n erters are giv n in IEC 6 14 -1-1, IEC 6 14 -1-2 a d IEC 6 14 -1-3

Volta e-s urc d c n erters are n t c n id re

Th re ort is c mpris d of thre p rts IEC 6 919-2, whic c v rs tra sie t p rforma c , wi

b a c mp nie b c mp nio d c me ts, IEC 6 919-1 for ste d -state p rf orma c a d

IEC 6 919-3 for d n mic p rf orma c An eff ort h s b e ma e to a oid d plc tio in th

thre p rts Co s q e tly u ers of this re ort are urg d to c n id r al thre p rts wh n

pre arin a s e ific tio f or p rc a e of a two- ermin l HVDC s stem

s e ific tio s a d e uipme t d sig s e ific tio s f or in ivid al c mp n nts of a s stem

Whie e uipme t s e ific tio s a d te tin re uireme ts are n t d fin d h rein, at e tio is

drawn to th s whic c uld aff ect p rforma c s e ific tio s f or a s stem Note th t d tai e

s ismic p rforma c re uireme ts are e clu e f rom this te h ic l re ort In a ditio ,

b c u e of th ma y p s ible v riatio s b twe n diff ere t HVDC s stems, th s are n t

c n id re in d tai Co s q e tly this re ort s o ld n t b u e dire tly a a s e if i atio

f or a s e if i proje t, b t rath r to pro id th b sis f or a a pro riate s e if i atio tai ore to

f it a tu l s stem re uireme ts for a p rtic lar ele tric p wer tra smis io s h me This re ort

d e n t inte d to dis rimin te th re p n ibi ty of u ers a d ma ufa turers f or th work

s e ifie

Terms a d d finitio s for hig -v lta e dire t c r e t (HVDC) tra smis io u e in this re ort

are giv n in IEC 6 6 3

Sin e th e uipme t items are u u ly s p rately s e ifie a d p rc a e , th HVDC

tra smis io l n , e rth ele tro e l n a d e rth ele tro e are in lu e o ly b c u e of th ir

in u n e o th HVDC s stem p rf orma c

For th p rp s of this re ort, a HVDC s b tatio is a s me to c n ist of o e or more

c n erter u its in tale in a sin le lo atio to eth r with b idin s, re ctors, f ilters, re ctiv

p wer s p ly, c ntrol, mo itorin , prote tiv , me s rin a d a xi ary e uipme t Whie th re

is n dis u sio of a.c switc in s b tatio s in this re ort, a.c f ilters a d re ctiv p wer

s urc s are in lu e , alth u h th y ma b c n e te to a a.c b s s p rate f rom th HVDC

s b tatio

IEC 6 14 -1-1, Semico duct or co verters – Ge eral re uireme ts and line commutat ed

co verters – P art 1-1: Sp cific tions ofba ic re uireme ts

Ame dme t 1 (19 6)

IEC 6 14 -1-2, Semico ductor co verters – Ge eral re uireme ts and li e commut at ed

co verters – P art 1-2: Ap lc tion g id e

IEC 6 14 -1-3, Semico ductor co verters – Ge eral re uireme ts and li e commut at ed

co verters – P art 1-3: Transformers and rea tors

IEC 6 6 3, Terminolo y for high-v ltag d irect cure t (H VDC) transmis ion

IEC 6 0 1-1, Insulat io co-ord inat io – P art 1: Terms, d efinit ions, principles and rules

IEC 6 7 0-1, Thyrist or valv s for high-voltag direct cure t (HVDC) p wer transmis ion –

P art 1: Electric l testi g

IEC TR 6 919-1:2 0 2 10, P erormance of high-v ltag d irect cure t (H VDC) systems with

li e-commutated co vert ers – P art 1: Steady-state co d itio s

IEC TR 6 919-3:2 0 , P erormance ofhigh-v ltag d irect cure t (HVDC) syst ems with

line-commut ated co v rters – P art 3: Dynamic co dit io s

3 Outl ne of HVDC transient per ormanc spe ific tions

3.1 Transient performan e specifications

A c mplete p rf orma c s e ific tio relate to tra sie t p rf orma c of a HVDC s stem

In g n ral, c ntrol strate ie c n b u e to minimiz th eff ect of disturb n e , b t wh n th

s fety of e uipme t d p n s o th ir c r e t p rforma c , this s o ld b id ntif i d

4 Switching transients without faults

4.1 General

This cla s d als with th tra sie t b h vio r of th HVDC s stem d rin a d afer switc in

o eratio s b th o th a.c a d th d.c sid s of c n erter s b tatio s, a d is n t relate to

e uipme t or ln fa lts whic are tre te in th f olowin cla s s of this re ort

Switc in o eratio s with ut f aults c n b cla sif i d a fol ows:

a) e ergiz tio a d d -e ergiz tio of a.c sid e uipme t s c a c n erter tra sformers,

a.c fiters, s u t re ctors, c p citor b n s, a.c l n s, static v r c mp n ators (SVC), a d

s n hro o s c mp n ators;

b) lo d reje tio ;

c) startin a d remo al from s rvic of c n erter u its;

d) o eratio of d.c bre k rs a d d.c switc e for p raleln of p le a d ln s; c n e tio

or dis o n ctio of d.c ln s (p le ), e rth ele tro e ln s, metal c return p th , d.c

f ilters, etc

4.2 Energiz tion an de-energiz tio of a.c side eq ipment

Durin th o eratin l fe of a HVDC tra smis io s stem, e ergiz tio a d d -e ergiz tio

of c n erter tra sf ormers, a.c fiters, s u t re ctors, c p citor b n s, SVCs, a d oth r

e uipme t ma o c r ma y time De e din o th c ara teristic of th a.c s stem a d

th e uipme t b in switc e , re ultin c r e t a d v lta e stre s s wi b imp s d o

e uipme t b in switc e a d g n ral y impin e a wel o p rt of th o eral a.c s stem

Th o erv lta e a d o erc re ts whic are critic l f or pla t d sig are u u l y d e to fa lts

(Cla s s 5 to 9), a d n t to n rmal switc in o eratio s Ne erth le s, th y are dis u s d

h re f or c mplete e s Th y are rele a t in c n id ratio of disturb n e to a.c s stem

v lta e

Fiter switc in wi als re ult in tra sie t distortio of th b s v lta e This c uld disturb th

c mmutatio pro e s a d in a we k s stem c uld le d to c mmutatio f aiure

Tra sie ts o c r ro tin ly wh n fi ters a d c p citor b n s are switc e a n c s ary to

c ntrol h rmo ic interfere c a d ste d -state termin l v lta e

Be a s of th f re u n y of o c r e c of switc in o erv lta e it is g n ral y d sira le th t

th o erv lta e prote tiv d vic s d n t a s rb a pre ia le e erg d rin s c o eratio s

o erv lta e f rom re trikin whic oth rwis c uld o c r wh n dis o n ctin f ilters or

c p citor b n s

Tra sf ormer e ergiz tio inru h c r e ts c n c u e a u d sira le intera tio in th a.c

a d d.c s stems Wh n dis o n ctin a c n erter tra sf ormer f rom th a.c n twork, th

tra sformer s o ld b dis o n cte maintainin th a.c f ilters c n e te in p ralel if

p s ible, in te d of dis o n ctin th tra sf ormer alo e or b u in s n hro izin d vic s In

th t wa , re id al s turatio wi b d cre s d, a d inru h c r e ts wo ld b re u e Af ter

s me h n re s of mi is c n s th f ilters c uld b dis o n cte f rom th tra sf ormer

To re u e inru h c r e ts, ty ic l c ntrol me s re in lu e circ it bre k r pre-in ertio

re istors, u in th s n hro iz d circ it bre k r, or s tin of th tra sf ormer o -lo d ta

c a g rs at th ir hig e t ta c a g r p sitio s Hig e t ta c a g r p sitio ref ers to th ta

c a g r p sitio with hig e t n mb r of win in turn Sy c ro iz tio re uire switc in at

a o timum in ta t in e c p a e, i.e bre k r clo in 9 d gre s af ter v lta e z ro cro sin

This imple th t th thre p le of a circ it bre k r c n ot switc simulta e u ly For

bre k rs with o e-p le o eratin me h nisms (a d th s a s p rate s n hro izin u it , this is

n t a pro lem Th s n hro izin u it is simply pro ramme to giv switc in ord rs s ita ly

s p rate in time to th p le Some bre k rs with thre -p le o eratin me h nism c n als

c n erter tra sformers c n aris f rom e ergiz tio of a oth r tra sf ormer in th c n erter

statio or from switc in of a SVC

Als th a pl c tio of low ord r h rmo ic f ilters c n b h lpf ul in re u in th pro lems with

inru h c re ts Th eff ectiv n s of s c me s re d p n s larg ly o th s stem a d

p rtin nt e uipme t c ara teristic In a ditio , th re p n e of th a.c s stem c n b

s n itiv to th n mb r of c n erter tra sformers alre d e ergiz d, e p cialy if th y are n t

y t lo d d a f or s rie c n e tio s of multiple c n erter u its

En rgiz tio of c p citor a d f ilter b n s c a g s th s stem imp d n e c ara teristic In

c s of s stem with relativ ly smal s ort circ it c p city, a din c p citiv c mp n nt s if ts

hig imp d n e p a of f re u n y-imp d n e c rv to lower f re u n y sid If th hig

pre ume d rin f aults To mitig te s c situ tio , d mpin re ister c uld b a d d to

dis h rg re istors are n t s f f icie tly ef f ectiv within th d sire switc in time

Altern tiv ly, a lo g r switc in time ma b n c s ary

En rgiz tio of f ilters e cite th f re u n ie to whic th y, in c mbin tio with th a.c

n twork, are tu e Als switc in o t of f ilter a d c p citor b n s c n c u e th a.c

s stem v lta e to o ci ate

+AMD1:2 15 CSV  IEC 2 15

SVCs c n b pro id d to sta i z th v lta e a d c ntrol temp rary o erv lta e En

r-giz tio of SVCs s o ld b s c a to pro u e a lg t or e e n tra sie t in th s stem

v lta e Mo t of th m h v a a tiv c ntrol whic c n b u e to a c mpls this o je tiv

Co n ctio or dis o n ctio of s u t re ctors a d c p citors pro u e c a g in a.c

v lta e Siz a d o eratio of this e uipme t s o ld b s e if i d s a to l mit switc in

-c u e v lta e c a g s to a c pta le le els

En rgiz tio a d d -e ergiz tio of a.c tra smis io l n s c n e te to HVDC s b-statio s

g n rate v lta e tra sie ts a wel, whic s o ld b ta e into a c u t Th s o eratio s

c a g th a.c h rmo ic imp d n e whic als in u n e th tra sie t h rmo ic ef fe ts

Sy c ro o s c mp n ators c n pro u e v lta e tra sie ts wh n starte a d o erate a

in u tio motors, drawin re ctiv p wer a d re u in th s stem v lta e This a p ct of

th ir p rforma c s o ld b c refuly e amin d

A ta le of a c pta le le els of temp rary or tra sie t o erv lta e a d o erc r e ts d rin

switc in o eratio s of th v rio s s stem c mp n nts or pref era ly a dia ram of th

e p cte tra sie t o erv lta e a d o erc r e t le els v rs s time s o ld b d v lo e for

Th d sire p rforma c of th HVDC s b tatio s u d r th tra sie t c n itio s d s rib d in

th f ore oin s b la s s s o ld b state f or b th switc in in a d o t of th v rio s

– d e to u inte tio al trip in of th a.c circ it bre k rs at eith r termin l;

– d e to blo kin a d b p s of c n erter u its a a c n e u n e of c ntrol s stem a tio ;

– d e to lo s of g n ratio a d f or a multitu e of oth r p s ible c u e

Volta e le els o th a.c s stem wo ld ris primariy b c u e of th c n e u nt e c s of

re ctiv p wer c mp n atio at th HVDC s b tatio Re o a t c n itio s c n b re c e

d e to s turatio of th p wer tra sformers a d re o a c s b twe n tra sformers, fiters a d

th a.c n twork Th s o erv lta e eff ects c n b a c ntu te b fre u n y d viatio s in th

a.c s stem

Sp cial c re s al b ta e for th c s th t th in erter b c me is late from th a.c

s stem with o ly th fiters a d s u t c p citor b n s c n e te to it

For this c ntin e c , th in erter s al b blo k d a d b p s e to pre e t o erv lta e

-c u e d ma e to th fiter c mp n nts or th a.c sid ar e ters or th v lv ar e ters

Op nin of th remote e d circ it bre k rs, for a s stem with a sin le or o ly a few ln s

c n e tin th in erter to th a.c s stem s al b ta e into a c u t in th d sig of th

prote tiv s h me

+AMD1:2 15 CSV  IEC 2 15

Ac e ta le lo d reje tio -c u e o erv lta e , in terms of ampltu e a d d ratio s s o ld

b s e if i d p rtic larly if th re ultin stre s s are e p cte to b gre ter th n th s

dis u s d in 4.2

Suita le o eratin strate ie to return to n rmal o eratin c n itio s s o ld b d v lo e

Amo g th pro e ure for a hie in this are c ntrol n th c n erter u its sti in s rvic to

re ulate th s stem v lta e or switc in in re ctors or b remo al of c p citor or fi ter b n s

If c p citor or fiter b n s are to b switc e u d r o erv lta e c n itio s this s al b ta e

into a c u t wh n fixin th a s ciate circ it bre k r ratin s a d c p bi tie In c s s wh n

a e istin circ it bre k r of in d q ate c p city c uld b c l e o to p rform this d ty, its

o eratio s o ld b in ibite a d oth r me n u e to re u e o erv lta e

Wh n c n erters are to b u e f or v lta e c ntrol, c n id ratio s o ld b giv n to th

d sig a d ma ufa ture of th v lv s f or o eratio at larg d la a gle

Th e te t to whic c n erter me s re c n b u e for re u in a.c s stem o erv lta e wi

d p n o th re uireme ts for c ntin ity of s p le p wer to s tisfy th a.c s stem

d n mic p rforma c

Oth r me n , s c a switc e c p citors or re ctors, s n hro o s c mp n ators, SVCs,

s e ial metal o id (MO) temp rary o erv lta e a s rb rs (TOV), etc ma n e to b u e

to l mit o erv lta e to a c pta le le els a d to a hie e th d sire c n erter p rforma c

As in mo t s stem d sig d cisio s, e o omic wi pla a major role Howe er, tra e-of fs

ma b n c s ary b twe n c st a d s stem p rforma c

4.4 Start up an sh t d wn of c nverter units

Normal o erator-initiate start u a d s ut d wn pro e ure for a HVDC p le s o ld b

e ta l s e

Start u a d s ut d wn of s rie -c n e te c n erter u its is p rf orme b th c ntrol

s stem s metime in c nju ctio with th o eratio of switc in d vic s in p ralel with th

c n erter u its For this p rp s n rmal y a a tomatic s q e c is folowe in whic a v lv

b p s p th within th brid e is a tiv te b f ore th o e in or clo in of th b p s switc

For this pro e ure a y s e ial re uireme ts or c n traints s c a th ma imum alowa le

a.c b s v lta e v riatio , s e ial interlo k re uireme ts or ma imum v riatio in tra smite

p wer, etc s o ld b s e ifie

Wh th r th s stem is to b o erate with a smal er n mb r of c n erters th n in th

ultimate c nfig ratio , p rtic larly d rin th d v lo me t sta e of th proje t, s o ld b

– d vic s whic are u e for o e in at z ro c r e t, e e th u h th y ma h v l mite

ma in a d bre kin c p bi ty;

– d vic s whic are a le to tra sf er th c re t from o e c r e t p th to a p ralel o e; s c

inter u tio d rin th tra sfer;

– a d d.c bre k rs whic are a le to inter u t a y d.c c r e t within th ir ratin s a d

with ta d th fol owin re o ery v lta e

In th f uture, d.c bre k rs ma b u e in ord r to alow a u re tricte p ral el n or d

-p ralel n of s b tatio or d.c l n p le A s e ial a pl c tio of th d.c bre k r is th

metal c return tra sfer bre k r (MRTB)

Zero c r e t o erate switc e a d d.c circ it bre k rs with a c re t inter u tin c p bi ty

n t e c e in th lo d c re t s al b c -ordin te with th c ntrol s stem a tio s u d r

b th fa lt c n itio s a d d rin o eratin s q e c s For e ample, s b tatio or l n p le

p ralel n a d d -p raleln o eratio s re uire th o e in a d clo in of v rio s switc e

Th s o eratio s initiate a wid v riety of v lta e a d c r e t tra sie ts a d s c f un tio s

are p rforme d rin e ta ls e o eratin s q e c s a d termin d b th d.c c ntrols

Th s, th tra sie ts d p n o th c ntrol s stem, o th switc o eratin time a d th a.c

a d d.c s stem ele tric l c ara teristic

For a two- ermin l s stem wh re rela i ty re uireme ts are strin e t, th u e of d.c circ it

bre k rs off ers th p s ibi ty of e h n in tra smis io rela i ty a d a aia i ty b th u e

of tra smis io ln s in p ral el a d s ctio al z d alo g th ir ro te This wo ld p rmit

is latio of o e of th p ralel ln s or l n s ctio s eith r in th c s of a p rma e t f ault or

f or o eratin n e s with ut e e a mome tary s ut d wn of th d.c tra smis io

Th s ma imum tra smis io c p bi ty within th th rmal lmits of th remainin h alth

circ it c uld b maintain d Of c urs , s le tiv prote tio s a in th c s of p ralel a.c

ln s wo ld n e to b u e

Th o eratin c ara teristic in lu in s e d re uireme ts s o ld b d termin d a d

c ara t er Ex mples:

C Co v ert er S -1 Ne t ral b s switc

F Fit er S -2 Gro n ret urn tra sfer switch

L Lin S -3 Ne t ral b s gro n in swit ch

N Ne tral SC-1 By pas switc

SC-2 By pas switc h

HV DC ln p le 2 Elec t ro e ln

HV DC ln p le 1

IE 175/0

Figure 1 – DC-side switc e f or an HVDC su statio

with s rie -c nnected c nverter unit

5 AC s stem f aults

5.1 General

Tra sie t p rf orma c of a HVDC s stem d rin a.c s stem f aults a d d rin th re o ery

p rio imme iately f olowin f ault cle rin are imp rta t c n id ratio s in th s e if i atio

+AMD1:2 15 CSV  IEC 2 15

s e ific c ntrol strate ie wi dire tly aff ect th ratin s of th HVDC e uipme ts, th

c n e te a.c s b tatio f aci tie a d th c n e te a.c n twork re p n e

5.2 Fault categ rie

Th f olowin a.c f aults s o ld b c n id re wh n pre arin a HVDC s stem s e ific tio :

– s n in e d (re tifier) a d re eivin e d (in erter) f aults f or e c p wer f l w dire tio ;

– thre -p a e to e rth a d sin le-p a e- o-e rth f aults at th HVDC s b tatio s;

– a.c f aults remote from th HVDC s b tatio s; re lo in pra tic s s o ld b c n id re ;

– v rio s fa lts a a o e in a.c or d.c l n s in c s s wh re th re is a p ral el a.c l n

clo ely c u le to th d.c ln Th e treme c s of this ty e is a fla h v r f rom a a.c to

a d.c c n u tor wh re a.c a d d.c ln s cro s

HVDC s e if i atio s c n ernin tra sie t p rforma c d rin a d af ter a.c s stem f aults

s o ld c n id r al af fe te are s of th d.c a d a.c s stem o eratio a d e uipme t ratin s

To a hie e a o timum b la c b twe n total s stem c sts a d p rforma c , tra e-off s

In its simple t f orm eff ectiv a.c s stem imp d n e is u u l y e pre s d a th s ort circ it

ratio (SCR), th t is, th ratio of th a.c s stem s ort circ it MVA to c n erter d.c p wer

(MW) ratin

Howe er, SCR is more pre is ly e pre s d a a.c s stem a mita c o a b s of rate d.c

p wer a d a.c v lta e This is d fin d at s stem f re u n y a d s o ld in lu e a a gle For

ma y stu ie th total a mita c s e b th c n erter is rele a t, in lu in th t of fi ters

a d oth r re ctiv p wer eleme ts c n e te to th HVDC s b tatio a.c b s; this is k own

a eff ectiv s ort circ it ratio (ESCR) Mo t sig if i a t are th imp d n e at th low-ord r

h rmo ic fre u n ie

SCR a d fin d h re difers from th ratio RSC d fin d in IEC Pu l c tio IEC 6 14 -1-1

wh re th b s is th rate MVA of th c n erter

Tra sie t f ault p rf orma c f actors af fe te b th SCR are:

a) p wer tra sf er d rin fa lts to maintain sta le o eratio with ut c mmutatio faiure ;

b) re o ery time, e p cial y for in erter e d fa lts;

c) c ntrol of p st f ault re o ery v lta e within a c pta le l mits;

d) p s ible low f re u n y re o a c c n itio s, i.e < 5th h rmo ic;

e) temp rary o erv lta e

Al of th s fa tors b c me more pro o n e with in re s s in th a.c s stem imp d n e

a d p a e a gle

5.3.2 Power transfer d ring faults

Th HVDC s stem ma b s n itiv to relativ ly remote a.c s stem f aults wh re a.c v lta e

c a g s at th HVDC a.c b s s are n t larg

+AMD1:2 15 CSV  IEC 2 15

Volta e d pre sio a d distortio a s ciate with a.c fa lts af fe t th d la a gle of th

c n erters a d c u e a re u tio in th tra smite d.c p wer For remote thre -p a e fa lts

th p wer lo s is e s ntial y pro ortio al to th a.c v lta e dro , d wn to a le el of d.c

v riety of s c c ntrols; a e ample c ara teristic is s own in Fig re 2

In c s th c n erters are u e for re ctiv p wer c ntrol, th in ut v lta e for th v lta e

d p n e t c ntrol s o ld b th a.c b s v lta e

Sy tem stu ie s o ld b ma e to d termin o timum s tin s for d.c or a.c v lta e

thre h ld , c r e t l mits, a d time c n ta ts or ramp rate , if a y, for e c s stem

For a.c sin le p a e- o-e rth fa lts to or n ar th re tifier termin l, th re u tio in p wer

tra sfer for mo ern c n erters is als a pro imately pro ortio al to th a era e a.c v lta e

dro , sin e d la a gle u b la c c n b re di y in orp rate to c mp n ate for larg a.c

v lta e dis ymmetrie

On th oth r h n , for mo t in erter c ntrol strate ie u in e uidista t firin s h me , th

e rle t firin time whic is s t to minimiz c mmutatio fai ure , fix s th firin time for al

v lv s This c ntrol a tio in c nju ctio with v lta e d p n e t c ntrol n rmal y re ults in

minimum p wer tra sfer d rin a.c sin le-p a e in erter e d fa lts Strate ie th t tra sfer

to in ivid al-p a e c ntrol o eratio d rin in erter e d a.c l n - o-e rth fa lts ofer o e

me n for in re sin th p wer tra sfer from th aforeme tio e minimum with ut

e p rie cin a e c s iv n mb r of c mmutatio fai ure

To a hie e b th sta le p wer tra sfer a mu h a p s ible a d a oidin c mmutatio faiure

d rin fa lts, o timiz d c ntrol of margin a gle c n b a pl e For e ample, dire t or in ire t

margin a gle d te tio of th th ristor v lv c n b impleme te a d a ple to clo e lo p

margin a gle c ntrol If s stem re uire , th s f un tio c n b s e ifie

Power tra sfers a hie a le u d r a.c fa lt c n itio s d p n larg ly o th c ara teristic

of th HVDC s stem u d r c n id ratio a d th refore c n b st b d termin d b digital

a d/or simulator stu ie

5.3.3 Rec very fol owing fault cle rin

Th re o ery time c n b d fin d a th t time re uire afer th f ault cle rin for th HVDC

s stem to re o er to a s e if i d le el of th prefa lt p wer, ty ic ly to 9 %, with th

o ers o t a d s tl n time b in s e ifie

HVDC s stem re o ery time c n b fa t, e.g 5 ms to 10 ms, with mo ern c ntrol s stems

f or al n n-p rma e t a.c fa lts at th re tifier or in erter for low imp d n e a.c s stems In

pra tic h we er ma y HVDC s stems b in d sig e or in tale are c n e te to hig

imp d n e a.c s stems at eith r HVDC s b tatio In s c c s , re o ery time c n b

s v ral time lo g r th n for HVDC s stems c n e te to low imp d n e a.c s stems L n

re o ery time c n als b e p cte for HVDC s stems ma in u e of lo g d.c c ble a d

v ry lo g d.c o erh a l n s

Re o ery time s t in s s al ta e into c n id ratio th a.c s stem sta i ty c ara teristic

for b th primary a d p s ible b c u fa lt cle rin time

its c ntrol strate y Volta e d p n e t c r e t lmits with taiore c ara teristic are of te

uti z d to mo ify th re ctiv p wer c n umptio a a f un tio of v lta e a d to impro e th

in erter's a i ty to re o er with ut c mmutatio faiure

Strate ie ma b a o te for th remote u fa lte HVDC s b tatio a d wh re pra tic l at

th fa lte s b tatio to c ntin e re ctiv p wer c n umptio or v lta e s p ort at a le el

to maintain a.c b s v lta e within pre crib d l mits

Durin c mmutatio fai ure , sig ific nt v riatio s o c r in re ctiv p wer flow Persiste t

c mmutatio fai ure in c n erters fol owe b prote tiv a tio re ult in re ctiv p wer flow

b in reje te into th a.c s stem whic c n le d to s b ta tial o erv lta e o hig

imp d n e s stems

HVDC s stem stu ie are imp rta t to d termin th re uire me n to c ntrol v lta e at

th a.c b s a d to maintain c mmutatio a wel a sta i ty of th interc n e te a.c

n twork

5.3.5 Load rejectio due to a.c faults

Fa lt c n itio s whic c n re ult in c n erter blo kin , trip in of lo d , faiure to d blo k

u o cle rin of thre -p a e f aults a d s v re c mmutatio f aiure , al re ult in f orms of

lo d reje tio whic c n initiate larg temp rary o erv lta e , f erore o a c , a d a.c

s stem in ta i tie whic c n c u e s stem c la s

In a ditio o s me a.c s stems c ref ul ate tio s al b giv n to th p s ibi ty of larg d.c

lo d reje tio s le din to s lf e citatio of g n rators or s n hro o s c mp n ators at or

prote tio to s tisfa tori y with ta d s c lo d reje tio o erv lta e

Whie n t blo kin , th c n erter c n b u e to h lp l mit o erv lta e Howe er

c n id ratio s al b giv n to th p s ibi ty of c n erter blo kin d rin a.c s stem f aults

+AMD1:2 15 CSV  IEC 2 15

me s re s c a hig s e d switc in d vic s f or re ctiv p wer e uipme t, static v r

c mp n ators (SVC), low ord r d mp d fi ters or prote tiv e erg dis ip tio d vic s to

re ctor b n s is a c mmo strate y at th a.c termin ls of HVDC s b tatio s f or c ntrol of

h rmo ic interfere c a d ste d -state termin l v lta e , th later a a f un tio of a.c

s stem lo din or of th primary a.c s stem v lta e

Wh n s e ifyin th switc in d vic to switc fi ters, s u t re ctors or s u t c p citor

b n s, ate tio s al b giv n n t o ly to th n rmal ste d -state inter u tin c p bi ty

a d s e d, b t als to th o erv lta e re uireme ts whic ma re ult from a.c fa lt

cle rin a d larg lo d reje tio

Furth r c mplc tio s ma b c me a p re t if a e istin re ctiv p wer switc in d vic

is in d q ate for s fe inter u tio d rin temp rary lo d reje tio o erv lta e , in whic

dis o n ctio of e c s re ctiv p wer s urc s

5.3.7 Ef ects of harmo ic v ltage an c r ent during faults

Multiple c cle c mmutatio fai ure or mis re o c r in d rin a a.c fa lt or th re o ery

p rio ma c u e c r e ts a d v lta e at low-ord r n n-c ara teristic h rmo ic a d e cite

oth r fre u n ie , o th a.c a d d.c sid s Th s ma temp rari y e cite re o a c s in th

a.c or d.c s stems, b t th re ultin c r e ts a d v lta e n rmaly are n t e c s iv , p rtly

b c u e of th d mpin pro id d b mo ern c ntrol s stems Howe er, s c eff ects s o ld

b stu ie to c e k th ef fe t o , for e ample, f ilter tra sie t ratin s, a d p s ible

mis erforma c of a.c s stem prote tiv rela s

If th d.c sid is re o a t at th fu d me tal fre u n y, s turatio of th c n erter

tra sformers c n o c r This wo ld a d to a y s c n h rmo ic o th primary a d c u e

p s ible s stem in ta i ty Als a a.c sin le-p a e- o-e rth fa lt n ar th re tifier

termin l inje ts larg s c n h rmo ic v lta e o th d.c sid th t wi remain a lo g a

firin c ntin e Be a s of th s c n id ratio s it is a vis ble to stu y c reful y th

p s ibi ty of a y re o a c of th d.c l n to this h rmo ic

Harmo ic g n rate d rin fa lts s o ld b ta e into a c u t in th d sig ratin s for th

a.c fi ters a d in d terminin th in erter's a i ty to c mmutate d rin fa lt re o ery

p rio s

A f urth r pro lem whic s o ld b c ref ul y e amin d is p s ible mis p ratio of th a.c

prote tio d e to low ord r h rmo ic d rin a.c fa lts In this c s th t digital ty e rela s

5.3.8 Shif in c ntrol mode of operatio

Ch n e in o eratin mo e , th t is, to p wer or c r e t c ntrol mo e for e ample, ma b

+AMD1:2 15 CSV  IEC 2 15

c ntrol le d to a p wer re u tio th t re uire a c re t ord r a ju tme t to c r e t for th

p wer lo s Als c -ordin tio of c r e t margin with a d with ut e d- o-e d

c mmu ic tio s a d c a g s in re ctiv p wer d ma d with c r e t margin c r e tio

s o ld b in e tig te

In s me hig imp d n e a.c s stems, u sta le o eratio s d rin fa lt initiate tra sie ts c n

a p ar in th p wer c ntrol mo e u le s a switc o er is ma e to c r e t c ntrol, or th p wer

c ntrol mo e is ma e to a s me c n ta t c r e t c ntrol mo e c ara teristic

5.3.9 Power mo ulatio on the HVDC system

AC s stem tra sie t sta i ty a d HVDC fa lt re o ery p rf orma c s metime c n b

impro e b th u e of p wer, dire t c r e t or dire t v lta e mo ulatio This o tio wi b

dis u s d in IEC 6 919-3

5.3.10 Emergen y power red ctions

Durin fa lt c n itio s re ultin in critic l a.c l n o ta e , c p bi ty for emerg n y p wer

re u tio s or e e p wer re ers ls ma b re uire a a c ntin e c o tio to mitig te a.c

s stem in ta i ty Th s e ific tio s s o ld c n id r th imp ct of s c c ntrol a tio s o :

– p s ible o erv lta e or d sta i z tio of th a.c s stem c n e te to th o p site e d

s b tatio a a re ult of th p rtial lo d reje tio ;

– c mmu ic tio s time re uireme ts to c -ordin te th emerg n y re u tio s plu p st

fa lt p wer in re s s a d th imp ct of p s ible c mmu ic tio s lo s

In s me c s s fa lt re o ery from a.c fa lts ma p rmit o eratio of th d.c s stem at a

re u e p wer le el u ti oth r re torativ a tio s h v b e a c mpl s e a d termin d

b a pro riate s stem stu ie

5.4 Specification impact o c ntrol strateg

Be a s of th wid ra g of a.c s stem c n itio s th t s al b c n id re in d terminin

o timum tra sie t p rforma c d rin a.c f aults a d d rin th re o ery p rio folowin

f ault cle rin , n sin le c ntrol strate y wi b a pro riate for al c s s Ea h s stem s al b

o timiz d aro n s e if i d refere c c n itio s a d termin d b digital c mp ter a d/or

a alo simulator stu ie f or th t p rtic lar s stem

Perf orma c s e ific tio s s o ld p rmit d.c c ntrol strate ie whic a hie e a o timum

c mpromis b twe n maintainin p wer tra sf er a d th pre e tio of c mmutatio faiure ,

in ta i tie or e c s iv re o ery v lta e , pro id d th t th o eral re ult is a s tisf actory

s lutio for th interc n e te a.c s stem

+AMD1:2 15 CSV  IEC 2 15

I

op.u

R

I

re tif i r a d in erter time c nsta ts, resp ctiv ly

Fig re 2 – Example of v ltage depen ent c ntrol c aracteristics

Inv ert er

R ectifier

F r d cre sin I

o:

+AMD1:2 15 CSV  IEC 2 15

6 AC fi ters, re ctive power equipment and a.c bus faults

6.1 General

This cla s dis u s s f aults in a.c h rmo ic f ilters, in re ctiv p wer e uipme t a d f aults o

th a.c b s ar Relativ ly hig le els of h rmo ic c re ts whic ma a p ar in th s items

war a t a dis u sio of prote tio a p cts This is in lu e Sp cific fa lt prote tio a p cts

s c e sful y An altern tiv ar a g me t, s metime u e is to c n e t th fiter a d th

c p citor a d re ctor b n s via tertiary win in s o th c n erter tra sformers

Th fu d me tal a d h rmo ic fre u n y imp d n e of th fi ters a d th re ctiv p wer

fra tio of th ln - o-e rth v lta e Howe er u d r tra sie t c n itio s th pro p ctiv

v lta e a ro s th fiter re ctors a d re istors c n b e e hig er th n th n rmal ln - o

-e rth v lta e Th ref ore s rg ar e ters prote tio s o ld b a pl e intern l y in th fi ters

a dis u s d in Cla s 12

In a ditio to th o erv lta e o c r in ro tin ly a a c n e u n e of n rmal switc in

(s e Cla s 4), th fi ter c mp n nts are l k ly to b s bje te to l g tnin -c u e o e

r-v lta e , switc in s rg s a d b s ar or e tern l clo e-in fa lts

Sin e th fi ter c p citors e hibit low imp d n e to fa t wa efro ts s c a from l g tnin

dis h rg s, th fi ter re ctors a d re istors wi b almo t dire tly e p s d to a y l g tnin

o erv lta e a p arin o th a.c b s ar

Switc in s rg o erv lta e a p arin o th a.c b s ars ma b sig ific ntly ma nifie

intern ly in th fiters a d th re ultin c mp n nt o erv lta e ma e e e c e th a.c

b s ar- o-e rth v lta e Th refore th in ivid al c mp n nt o erv lta e s o ld b

in e tig te d rin o erv lta e stu ie Wh n th c mp n nts are n t dire tly prote te b

s rg are ters, a is of te th c s f or th main fi ter c p citors, th y ma n e to b

d sig e to with ta d hig er switc in s rg le els b twe n th ir termin ls th n oth r

dire tly prote te e uipme t c n e te from th b s ar- o-e rth

Durin u b la c d a.c s stem fa lts, th c n erters, if n t blo k d, wi g n rate low ord r

h rmo ic of s b ta tial ampl tu e If fi ters for low ord r h rmo ic are u e , th f ilter s rg

ar e ters ma b re uire to a s rb c n id ra le e erg u d r th s c n itio s An th r

e erg stre s c n itio to c n id r p rtic larly for f ilter re ctor s rg ar e ters of th s c n

or third h rmo ic fiters (wh n s c fiters are pro id d), is d rin e ergiz tio of larg

tra sformers ele tric ly clo e to th f ilter b s s c a at re o ery from a clo e a.c fa lt

Se ere o erv lta e with fa t fro t time c n o c r a ro s th re istors a d re ctors

within th fi ters ifa a fla h v r from th a.c b s ar- o-e rth s o ld ta e pla e in th

HVDC s b tatio Th pro p ctiv v lta e ampl tu e a ro s th s fi ter eleme ts wi b

e u l to th pre- la h v r v lta e a ro s th main fi ter c p citor a d th s rg ar e ter

+AMD1:2 15 CSV  IEC 2 15

6.3 Transient overc r ents in fi ter and capacitor ban s

Un er tra sie t c n itio s p a c r e ts in th f ilter c mp n nts ma b s v ral time

gre ter th n th n rmal ste d -state v lu s

In th e e t of a f l s o er from b s ar- o-e rth th c p citor b n s wi dis h rg e erg into

th fa lt Th c r e t in this dis h rg wi b lmite b th stra in u ta c of th c p citor

sta k a d its b s ar c n e tio s a d b th c r e t lmitin in u tor if u e Simi arly, wh re

s rg ar e ters are pro id d a ro s re ctors a d re istors in a.c h rmo ic fiters, th

c p citor dis h rg c re t c n b hig sin e it is o ly lmite b th b c e.m.f of th

prote tiv d vic a d b stra in u ta c

Du c n id ratio to th s o erc r e ts s o ld b giv n in th s e if i atio s of th

c mp n nts a wel a of th prote tiv circ its a d th d sig of th e rthin s stem Th s

c p citor fu e s al b c p ble of with ta din th dis h rg c r e ts, a d th o eratio of

c r e t tra sformers a d prote tiv rela s s o ld n t b a v rs ly af fe te n r s o ld th

prote tio b in or e tly trig ere b tra sie t c r e ts whic are within th c p bi tie of th

f ilter c mp n nts Th s s o ld b d sig e to with ta d s c dis h rg s

Th a aly is s o ld c n id r th s stem c nfig ratio , in lu in th fi ters a d s u t

c p citors, le din to th mo t critic l stre s s

6.4 Capacitor u balance protectio

To a hie e th d sire h rmo ic p rf orma c a d re ctiv p wer b la c at al d.c lo din s

th c p citor a d fi ter b n s are u u ly divid d into a n mb r of switc a le arms This

me n th t th in ivid al b n s (arms) ma b of relativ ly low MVar ratin , i.e th n mb r

of p ral el eleme ts in th c p citor b n s wo ld b smal

Durin th o eratin l fe of a c p citor b n , c p citor eleme ts c n f ai a d b dis o n cte

b f us o eratio Wh n intern l f us s are u e , th ir o eratio dis o n cts th in ivid al

intern l f aulty eleme t, whi e e tern l fu e o eratio wi dis o n ct th c mplete c p citor

c l

Ca a itor b n s are ofe d sig e to h v b i t in re u d n y whic me n th t a lmite

n mb r of c p citor eleme t f aiure a d th a c mp n in f us o eratio s wi n t

o erstre s th remainin h alth c p citors in th b n Howe er fu e o eratio s s o ld b

d te te s re u d n y c n b re tore in th b n at a e rly c n e ie t o p rtu ity

On meth d of s c d te tio is u e of c r e t u b la c rela prote tio For this s h me

e c p a e of th c p citor b n is c n e te in a brid e circ it, i.e “H” c n e tio If a

eleme t fu e blows in o e c p citor u it, th c p cita c of th brid e arm, th t c ntain this

u it wi d cre s , c u in a u b la c c re t in th brid e arm whic is me s re b th

c r e t tra sf ormer

An th r meth d of s c d te tio is th t e c c p citor p a e is s b ivid d into two clo ely

e uiv le t p ral el gro p of c p citors Se sitiv c r e t u b la c rela s re p n in to

th difere c in c r e t in th bra c e are uti z d to d te t smal c a g s re ultin from

For s me a plc tio s two le els of u b la c d te tio are u e Th f irst giv s a alarm

a d p rmits ma u l d -e ergiz tio of th c p citor b n a d re la eme t of f ai e c p citor

u its a n c s ary to re tore re u d n y Th s c n le el giv s a a tomatic trip sig al to

+AMD1:2 15 CSV  IEC 2 15

c n e u n e of th lo s of a larg n mb r of c p citor u its or eleme ts Un ala c

prote tio s h me a s me a e tremely low pro a i ty of th s me d gre of c p citor

eleme t fai ure simulta e u ly in two bra c e of a fiter c p citor b n

6.5 Example of protectio of fi ters and capacitor banks

Ex mple of prote tio ar a g me ts for fiters a d c p citor b n s f or a HVDC s stem are

i u trate in Fig re 4, 5 a d 6 Th c oic is u u ly b s d o in ivid al uti ty e p rie c

a d pra tic s

If re u d n y is s ficie t to al ow a p le to c ntin e to o erate e e with o e fi ter o t of

s rvic , it ma b d sira le to prote t th fi ter arms in ivid al y, s th t th fa lty fiter c n

b dis o n cte ra idly with minimum lo s of tra smis io c p bi ty

If lo s of a fiter me n th t th p le c n ot c ntin e o eratio , it ma th n b c n id re

e o omic l to pro id prote tio o ly for th o eral b n or to in lu e th fi ters in th

b s ar prote tio z n As a oth r altern tiv to in ivid al fi ter prote tio , s me

o eratio al re trictio s s c a re u tio in tra smite p wer c uld b c n id re

To e s re th t th a pro riate prote tio c ara teristic are a pl e , c ntin e c o eratio

re uireme ts for p rtial lo s of re ctiv p wer s urc s s o ld b stu ie a d s e ifie

Th pre e c of a e rth or p a e- o-e rth fa lt within a giv n prote tio z n c n b

d te te b a c n e tio al dif ere tial c r e t prote tio s stem a s own in Fig re 4

Wh n fi ters are a sig e th ir own in ivid al prote tio z n s, c r e t tra sformers s al b

pro id d in e c p a e o th a.c b s ar sid a d at th n utral sid of th fiter Wh n th

f ilter b n is tre te a a sin le prote tiv z n , o ly o e s t of hig v lta e c r e t

tra sformers n e b pro id d, situ te in th a.c b s ar c n e tio s

If trip in of th c mplete p le s o ld b initiate wh n th fi ter b n is trip e , th fi ter

b n c uld altern tiv ly b in orp rate in th o eral p le dif ere tial prote tio s h me

Howe er this wi h v th dis d a ta e of re u e a tomatic informatio for id ntific tio

of th fa lte b n

An th r z n prote tio s h me is th re tricte e rth fa lt prote tio s own in Fig re 5

This u e c r e t tra sformers in e c of th thre hig v lta e p a e c n u tors a d in

th n utral c n e tio s to d te t a e rth fa lt in th prote te z n

It s o ld b n te th t if th s rg ar e ters in id th fiter b n s are c n e te dire tly to

s stem a a u b la c c r e t Th re ultin pro a i ty of u d sira le rela o eratio s

c n b minimiz d b pro er c -ordin tio or b in lu in th ar e ters in th prote tio

Ov rc r e ts whic re ult f rom a n rmal a.c b s ar v lta e ofe c n b tolerate for

lmite time with ut e c s iv p n ltie in terms of lo t e uipme t lfe Howe er th

e uipme t s o ld b mo itore s th t mitig tiv ste s ma b ta e b fore s c o erlo d

e c e th l mits imp s d b th k own margin in ere t in th e uipme t For this,

prote tio c n b o tain d b me s rin th c r e t in e c p a e a d u in o erc r e t a d

o erlo d rela s To e s re a e u te prote tio a ain t th s pro lems in a a.c h rmo ic

+AMD1:2 15 CSV  IEC 2 15

f ilter it is ofe n c s ary to pro id c r e t tra sformers for in ivid al eleme ts of th fiter

a s own in Fig re 6

6.6 Sh nt re ctor protectio

Th prote tio ar a g me t for a s u t re ctor a ple at a HVDC s b tatio for re ctiv

p wer c ntrol is simi ar to th t a ple to a re ctor or tra sformer a u e in a a.c

tra smis io s stem

6.7 AC b s protectio

Th c n erter a.c b s ar is n rmal y prote te b a dif fere tial prote tio s stem Sin e

re o a c s c n e ist b twe n th a.c f ilters a d th a.c s stem a hig c nte t of h rmo ic

c r e ts ma b pre e t in th b s ar c r e ts d rin fa lt re o ery p rio s Th b s ar

prote tio s stem th n s al o erate c r e tly in th pre e c of th s h rmo ic c re ts

An th r a p ct of this prote tio whic s o ld b e amin d is its p rforma c d rin

temp rary o erv lta e c n itio s Un er s me c n itio s th p a v lta e of o e p larity

ma b s b ta tialy hig er th n th oth r This c n re ult in u idire tio al s rg ar e ter

c r e ts It s al b e s re th t th c r e t tra sf ormers d n t s turate u d r th s

c n itio s sin e mis p ratio s of th prote tio c n oth rwis o c r

Fig re 4 – Example of c r ent transformer ar angements f or a.c fi ters

an a.c b s dif ferential protectio s

+AMD1:2 15 CSV  IEC 2 15

IE 17 /0

Fig re 6 – Example of c r ent transf ormers ar an ement f or capacitor bank u balance

protectio and o erload protection of d uble tu ed fi ter arm

7 Converter unit faults

7.1 General

This cla s dis u s s c n erter u it f aults, i.e th s whic ta e pla e b twe n th ln v lv

sid of th c n erter tra sformers a d th v lv sid of th smo thin re ctor

Ele tro ic e uipme t e tern l to th c n erter arms b t f un tio al y p rt of th m (s e

IEC 6 6 3), is in lu e in th dis u sio a a pro riate Co l n e uipme t is dis u s d in

Cla s 14

In s me a pl c tio s, c n erter u its c n b c n e te in s rie or in p ral el o th d.c sid

within o e p le of th HVDC s b tatio Fa lt a p cts of s c c nfig ratio s are als

a dre s d

Co v rter u it fa lts c n b cla sifie a :

a) fla h v rs or s ort circ its (s e 7.2);

b) fai ure of th c n erter u it to p rform its inte d d f un tio (s e 7.3)

Vario s prote tiv circ its are u u l y b it aro n th c n erter u it to d te t fa lts a d

o eratin c n itio s th t c n b d trime tal to th s fety of th e uipme t, p rtic larly th

th ristor v lv s Su cla s 7.4 lsts ty ic l circ its s me of whic c n b re uire o ly for

p rtic lar v lv d sig s

7.2 Sh rt circ its

Sh rt circ its c n b c u e b bre k own of e tern l or intern l in ulatio , b in d erte t

o eratio of switc e or f rom oth r c u e Th y c l for a s ut d wn of th af fe te

c n erter u it b c u e of th hig pro a i ty of e uipme t d ma e a d th n e f or re air or

re la eme t

+AMD1:2 15 CSV  IEC 2 15

In bip lar s stems or th s c mpris d of two or more in e e d nt c n erter u its p r p le,

th u af e te c n erter u its a d th s th remain er of th HVDC tra smis io s stem c n

remain o erativ afer a s ort circ it in a c n erter u it

For e ample, Fig re 7, s ows a n mb r of p s ible lo atio s of s ort circ its within a

ty ic l c n erter u it Fa lts within th c n erter tra sformer are n t s own sin e th y are

c n erter tra sformer a d s bje ts th c n u tin v lv in th s me c mmutatin gro p to

th ful y ofs t s ort circ it c r e t Th p s ibi ty of a fla h v r of th tra sformer n utral

Up n d te tio of a s ort circ it, p rh p b th dif fere tial prote tio within a HVDC

th ristor v lv c n erter, c mmo pra tic re uire imme iate blo kin of al g te p ls s to

pre e t furth r c mmutatio Th s ort circ it c r e t th n e tin uis e at its first z ro

cro sin , g n raly within th first c cle f olowin fa lt initiatio Su s q e tly th v lv s are

s bje te to th re o ery v lta e in lu in a y temp rary o erv lta e re ultin from d.c

lo d reje tio Th a.c circ it bre k r of th c n erter u it is trip e simulta e u ly a a

For a y giv n s stem, th ma imum v lv fa lt c re t a d th s th hig e t th ristor ju ctio

temp rature are o tain d with th ma imum a.c s stem f ault c r e t le el in lu in a y

c ntrib tio from th a.c f ilters On th oth r h n , th ma imum re o ery v lta e in lu in

lo d reje tio o erv lta e is in g n ral e p rie c d with th minimum a.c s stem f ault

c r e t le el

Valv s s o ld b s e ifie to h v fa lt s p re sio c p bi ty for c n iste t le els of s ort

circ it c r e t a d re o ery v lta e Bre k r faiure s o ld als b c n id re If thre p le

bre k rs are u e a d th bre k r f ai s, th b c u bre k r mig t b o e e af ter a o t 4 0

ms, a d th t time s o ld b c n id re f or v lv d sig If sin le p le bre k rs are u e , a d

o e bre k r p a e f ais, th fa lt c r e t wi b inter u te a ywa sin e mo t of fa lts are

fe from two p a e , a d n e tra time h s to b c n id re f or th v lv d sig If o e in

of th c n erter u it circ it bre k r is inte d d to pro id b c -u for f ault s p re sio

c p bi ty, th v lv s s o ld b s e ifie to h v s rviv l c p bi ty for th time p rio u ti

th bre k r cle rs

For f aults to e rth, in lu in fa lt B1, B2, B3 a d B5 in Fig re 7, v lv s n t stre s d b th

f ault c re t c n e p rie c f ast c a g s of p te tial De e din o circ it p rameters, this

ma s bje t th c n erter v lv s to stre s s e uiv le t to ste p- ro te v lta e s rg s

Sp cif i atio s th n s o ld re uire th t th c n erter u it e uipme t b d sig e a d

ma uf acture to with ta d re ulta t stre s s u d r cre ible f ault c n itio s, a dis u s d in

th fore oin , with ut d ma e

+AMD1:2 15 CSV  IEC 2 15

In th c s of CCC, s ort circ it of th c mmutatio c p citor wi n t giv a y d cisiv s ort

circ it c r e t for dime sio in of th main circ it e uipme t For dime sio in of th v ristor

a ro s th c mmutatio c p citor, v lv s ort circ it a d c mmutatio faiure / a.c s stem

sin le-p a e f aults s o ld b c n id re a th d cisiv fa lt c s s Th n mb r of

c n e utiv c mmutatio f ai ure / a.c s stem sin le-p a e fa lts s o ld b c ref ul y

c n id re a it ma b dime sio in f or th v ristors 2-p a e or 3-p a e fa lts b twe n th

CC a d th v lv s wo ld giv e ormo s e erg a d it is n t pra tic l y p s ible to dime sio

th v ristor for s c f ault c s s If th statio la o t is s c th t th s 2-p a e or 3-p a e

f aults c n ot b disre ard d, th y s o ld b c n id re for c r e t dime sio in p rp s s

o ly a d n t for v ristor e erg dime sio in

7.3 Fai ure of c nverter unit to perform its inten ed fun tio

7.3.1 General

Th b sic fu ctio of th c n erter u it is to c cl c ly c mmutate th dire t c r e t b twe n

th p a e of th a.c s stem To p rf orm this fu ctio , two c n itio s s al b f ulfi e :

s ff i ie t c mmutatio v lta e s al b pre e t; a d s n hro iz d c clc l g te p ls s s al

b g n rate b th c n erter u it c ntrol a d tra smite to th v lv f irin circ its

re uireme t o v lv d sig s, wh re a xi ary e erg for g tin or th ristor prote tio is ta e

f rom th main circ it, in th t th ele tro ic circ its s o ld b d sig e f or f ast re h rgin or

h v a e u te e erg stora e c p bi ty

Persiste t faiure of a v lv to turn o , p rh p d e to mis in g te p ls s, c u e th

fu d me tal a.c v lta e to b inje te into th d.c circ it De e din o circ it

p rameters, this c n le d to tra sformer s turatio , e cite p s ible re o a c s o th d.c

l n , etc p s ibly imp sin s v re stre s s o th af e te e uipme t Th s e ific tio

s o ld re uire th t s c fa lts b d te te a d a pro riate a tio s ta e (s e 8.7)

7.3.3 In erter o eration

Durin in erter o eratio th a s n e of a s ff i ie t c mmutatin v lta e- ime are or of

v lv g te p ls s re ults in c mmutatio fai ure This s bje ts th v lv to o erc r e ts a d

intro u e a fu d me tal a.c v lta e c mp n nt into th d.c circ it Sp cial c ntrol

strate ie s c a a v n in th d la a gle, b -p s p ir o eratio to el min te f un ame tal

a.c v lta e o th d.c sid , re u tio of dire t c r e t, etc are a o te to minimiz

c mmutatio fai ure a d th ir eff ects

If th c mmutatio f aiure is c u e b in uff i ie t a.c v lta e from a e e t s c a a a.c

s stem f ault (s e Cla s 5), th n n rmal p rforma c c n b e p cte to re ume o c th

f ault h s b e cle re To a oid s utd wn of th c n erter, th v lv s s o ld b d sig e

a d ma ufa ture to with ta d th stre s s re ultin from s c e e ts for a s e if i d time

a siste b th c n erter u it c ntrol If th s e if i d time is e c e e or if th c mmutatio

f aiure is c u e b mis in g te p ls s th n th c n erter s o ld b blo k d

For v lv d sig s wh re th a xi ary e erg re uire f or g tin th th ristors is ta e from

th main circ it, th p rtin nt ele tro ic circ its s o ld b d sig e f or f ast re h rgin or th y

s o ld h v s ff i ie t e erg stora e c p bi ty s th t th c n erter c n q ic ly re ume

n rmal o eratio af ter re p e ra c of th c mmutatin v lta e

+AMD1:2 15 CSV  IEC 2 15

7.4 Co verter unit protectio

7.4.1 Co verter dif erential protectio

By c mp rin th c n erter tra sformer v lv sid c re t to th dire t c re t, s ort circ its

within th c n erter brid e c n b d te te Th re ultin prote tiv a tio is to p rma e tly

blo k th c n erter u it a d trip th a s ciate a.c circ it bre k r

7.4.2 Overc r ent protection

Ev lu tin th ma nitu e of th tra sformer v lv sid c r e t ma e it p s ible to prote t

a ain t o erlo d This als pro id s b c u for c n erter diff ere tial prote tio Prote tiv

a tio is th s me a th t d s rib d in 7.4.1

7.4.3 AC o erv ltage protectio

AC o erv lta e prote tio c n b in lu e b me s rin th a.c v lta e, for e ample at th

v lv sid of th c n erter tra sformer u in a c p citiv v lta e divid r a in th tra sformer

b s in s or b oth r me n Prote tiv a tio s afer d te tin a u d sira le o erv lta e

mig t in lu e trip in of c p citor b n s, in re sin th c n erter re ctiv p wer

c n umptio , p rma e t blo kin of th v lv s alo g with trip in of th c n erter u it a.c

circ it bre k r or a a pro riate c mbin tio of th s a tio s

7.4.4 Protectio against large delay angle operatio

Prote tio a ain t larg d la a gle o eratio s c n b a hie e if re uire f or a p rtic lar

v lv d sig b me s rin th v lv d la a gle a d lmitin th d ratio of s c o eratio

in th c n erter u it c ntrol Th lmitatio s o ld b ma e d p n a t o v lv sid v lta e,

dire t c r e t a d th v lv c ola t temp rature

7.4.5 Commutation fai ure protection

Commutatio fai ure d te tio is u u l y a hie e b a.c./d.c c r e t diff ere tial

me s reme t If re o ery d e n t o c r n tural y, this a ts afer s me d la to temp rari y

in re s th in erter a gle of a v n e If n re o ery o c rs af er a f urth r d la , p rma e t

blo kin is a ple

7.4.6 Th ristor valve protections

Th ristor re u d n y c n b mo itore b c ntin o s o -l n c e kin of e c th ristor if

re uire Prote tiv a tio s c n in lu e a warnin sig al, s ut d wn a d is latio of th

c n erter u it or a c mbin tio of th s

Th ristor forward o erv lta e prote tio c n b a hie e b mo itorin th in ivid al

th ristor v lta e a d a plyin a g tin sig al if th s fe le el is e c e e (s e als

12.7.3) or b oth r me n

Forward re o ery prote tio c n b u e to prote t th th ristors a ain t p sitiv hig

v lta e/ime dif ere tial dv /dt in th re o ery p rio b a plyin a g tin sig al if a s fe

le el is e c e e , or b oth r me n

7.4.7 Transformer protectio

Co v rter tra sf ormer prote tio is th s me a c n e tio aly u e for tra sformers in a.c

tra smis io s stems It in lu e dif fere tial prote tio , o erc r e t prote tio , g s in or h t

s ot d te tio , etc Prote tiv a tio is to trip th c n erter u it a.c circ it bre k r

Pre a tio s s al b ta e to pre e t dire t c r e t from flowin in th tra sformer, f or

e ample b b p s -p ir o eratio a d th s to a sist th circ it bre k r cle rin This c n b

p rtic larly imp rta t f or s rie -c n e te c n erter u its

Sp cial ate tio s o ld b p id to th d sig a d ratin of c r e t tra sformers u e

b c u e of p s ible s turatio pro lems Pro lems of c n ern in lu e for e ample, inje tio

of dire t c r e t in c nju ctio with c mmutatio fai ure , n utral b s fa lts, a d d la e

n utral b s switc o eratio (s e Cla s 1 )

7.4.8 Transformer tap-c an er un alan e protection

Ta -c a g r u b la c prote tio ma b re uire to a oid u b la c d o eratio of th

c n erter u it, in turn le din to g n ratio of e c s iv n n-c ara teristic h rmo ic Th s

c n o erlo d fiters Prote tiv re p n e is to giv a alarm a d initiate a ma u l or a tomatic

ta c a g r re ala cin pro e ure

7.4.9 AC c n ection e rth fault protectio

AC c n e tio e rth f ault prote tio ma b u e to d te t e rth fa lts o th c n e tio s

b twe n th c n erter tra sformer a d th v lv s ( a lt B1 a d B2 in Fig re 7), wh n th

c n erter tra sf ormer is e ergiz d b t th v lv s are blo k d Th v lv sid v lta e of th

c n erter tra sf ormers c n b me s re b u in c p citiv v lta e divid rs in th

tra sf ormer b s in s or th v lv h l b s in s or b oth r me n Prote tiv a tio c n b

trip in of th c n erter u it a.c circ it bre k r

7.5 Ad itional protectio a pects of s rie c nnected c n erter u its

Wh n two or more c n erter u its are c n e te in s rie o th d.c sid within o e p le of

of th p le to remo e th dire t c r e t If th fa lt is within th c n erter u it 1 or 2 z n ,

re ume with th remainin h alth u it Co sid ratio s o ld als b giv n to remo in

o e of th c n erter u its from s rvic at th oth r e d of th tra smis io s stem to

a oid prolo g d o eratio at larg d la a gle or a gle of a v n e, re p ctiv ly

For c rtain f aults o c rin o ly in o e of th s rie c n e te c n erter u its, s c a

tra sf ormer f aults or c mmutatio fai ure , prote tiv s q e c s c n b u e in a ditio to

f ault remo al to div rt th dire t c r e t from th af fe te u it b b p s o eratio of th

c n erter v lv s or b clo in th b p s switc

7.6 Ad itional protection a pects of paral el c nnected c n erter u its

In g n ral, e c of th p ral el-c n e te c n erter u its c n b tre te in e e d ntly f rom

th p int of view of tra sie t p rforma c a d f ault prote tio Howe er, d e c n id ratio

s o ld b giv n to th tra sie t c r e t ratin of p ralel-c n e te in erters with re p ct to

c mmutatio fai ure , e p cial y if th in erters h v diff erin ste d -state c r e t ratin s DC

bre k rs ma b d sira le at th p le b s (s e Fig re 9), f or is latio of fa lty c n erter

u its, e p cialy in erters, to a oid th n e to temp rari y blo k th c mplete tra smis io

p le

1 sh rt circ it a ros lower v lta e 6-p lse brid e

2 sh rt circ it a ros hig er v lta e 6-p lse brid e

3 sh rt circ it a ros 12-p lse brid e

E A p ases sh rt circ it

1 2-p ase sh rt circ it

2 3-p ase sh rt circ it

F Pole to n utral b s sh rt circ it o tsid th d.c re ctor

G Pole b sto gro n f ault o tsid th d.c.re ctor

Figure 7 – Example of a.c p a e sh rt circ its, pole sh rt circ its and faults

in a twelve-p ls c n erter u it

Fig re 9 – Protection zone in paral el-c nnected c n erter u its

8 DC re ctor, d.c f ilter and other d.c equipment faults

8.1 General

This cla s dis u s s f aults in th HVDC s b tatio for a HVDC tra smis io s stem

b u d d b :

a) th v lv sid of th d.c re ctor to th d.c tra smis io l n in e c p le;

b) from th n utral sid of th c n erter u it for e c p le to th e rth ele tro e ln

Sp cific tio s for HVDC s b tatio s s o ld ma e pro isio n t o ly for th prote tio of al

d.c sid e uipme ts, b t als for th c -ordin tio of prote tio s

In HVDC s stems th z n prote tio p io o h a d te h iq e of impleme tatio to

a hie e z n s of prote tio are in g n ral mu h th s me a with a.c prote tio pra tic s

Howe er, in HVDC s stems th fa lt s p re sio c p bi ty of th c n erter v lv s (s e

Cla s 7), in a ditio to th relativ ly hig imp d n e of d.c re ctors a d tra sformers aid

in a hie in prote tio s le tiv ly o th d.c sid

Prote tio z n s of a HVDC s b tatio s o ld b ar a g d s c th t al e uipme t is f ul y

prote te b at le st o e prote tiv fu ctio within th HVDC s b tatio

A c mmu ic tio s stem b twe n s b tatio s of th HVDC tra smis io c n b u e to

o timiz re o ery f rom f aults a d to impro e f ault prote tio s le tivity for ma y f aults whic

c n ta e pla e o a HVDC tra smis io s stem Howe er it s o ld n t b n c s ary f or

b th p le Th later re uire a bip le s utd wn to pro id c r e tiv mainte a c

8.4.2 Neutral fault detectio

In a bip lar c n g ratio o eratin u d r b la c d c n itio s, th p le n utral prote tio

z n , th bip le n utral prote tio z n a d th e rth ele tro e ln prote tio z n (s e

Cla s 10) are al e s ntialy at e rth p te tial An e rth f ault in a y of th s z n s wo ld

th refore n t interfere with statio o eratio u d r b la c d bip lar c n itio s An d.c f ault

c r e t th n wo ld b pra tic l y z ro

Fa lts to e rth in th s n utral z n s wo ld b d te ta le wh n v r th p le of th bip le

are temp rari y u b la c d f or a y re s n s c a d rin startu , s utd wn or disturb n e

o o e p le Th HVDC s e ific tio s s o ld c n id r u e o ly of n utral z n alarms if th

o eratio of b th p le is e p cte to b re s n bly b la c d This wo ld alow o erator

d cisio o c r e tiv a tio s to b ta e b s d o s fety c n id ratio s a d th p wer

tra smis io re uireme ts at th time of fa lt d te tio

Th p le n utral a d bip le n utral z n s s o ld b b u d d b d.c c r e t tra sformers

(d.c.-c.t.) A fa lt within th re p ctiv z n s c n b d te te b a dif ere tial c mp ris n

of th c r e ts a me s re b th d.c.-c.t.'s at th z n b u d rie d rin a u b la c

o eratin c n itio b twe n th two p le

8.4.3 Neutral b s fault isolatio

Fa lts to e rth within th n utral z n or c n erter z n re uire a p rma e t sto of th p le

f or c re tio of th fa lte c n itio

Th n utral b s switc in d vic is uti z d d rin th prote tio s q e c to is late th

f aulte p le a d to tra sfer a y re id al p le c re t to e rth return

Cur e t tra sf er re uireme ts of th n utral b s switc in d vic s o ld c n id r th mo t

o ero s c n itio u to a d in lu in ma imum h alth p le c re t a d lo atio of fa lts

Th switc s al b c p ble of d v lo in a v lta e gre ter th n th IR dro of th e rth

return to forc th c r e t tra sf er For s stems in whic eith r e rth return or o -ln tra sfer

to metal c return are n t p rmite , lo d bre k c p bi ty of th switc in d vic ma n t b

s utd wn to pro id c r e tiv mainte a c whic c uld b a s h d le s utd wn

8.5 DC re ctor protectio

Th d.c re ctors of e c p le c n b eith r oi -in ulate or dry ty e Prote tio of oi ty e

Diff ere tial prote tio c n b s e ifie aro n th d.c re ctors or th s e uipme ts c n b

in lu e in o e of th HVDC s b tatio prote tio z n s a s own in Fig re 10 a d 1

Oi ty e d.c re ctor b s in d sig s le d th ms lv s to a e o omic s lutio to th pro lem

of h u in th d.c.-c.t.'s re uire f or diff ere tial prote tio

Wh n dry ty e d.c re ctors are emplo e , s p rately mo nte d.c.-c.t.'s wi b n e e f or

re ctor fa lt d te tio

8.6 DC harmonic fi ter protectio

8.6.1 General

Th d.c f ilters a s ciate with HVDC s b tatio s are n rmal y s e ifie to lmit h rmo ic

interfere c c u e b h rmo ic c r e ts f l win into th d.c l n (s e IEC 6 919-1,

Cla s 17)

Prote tio d sig for th d.c f ilter arms s o ld ta e into a c u t th f ul ra g of n rmal a d

a n rmal o eratin c n itio s whic s o ld b s e ifie f or th HVDC s b tatio s

Simiarly th prote tio d sig for th d.c fiter eleme ts, s c a c p citors, re ctors,

d mpin re istors, a d dis o n ctors s al c n id r al e p cte o eratio al c n itio s th t

re ult in fiter eleme ts b in o erstre s d d e to h rmo ic c re ts whic f or e ample c n

re ult from o eratio at larg d la a gle , a gle of a v n e or from re o a t c n itio s,

An fa lt within th d.c fiter z n ma b d te te b a dif fere tial c mp ris n b twe n th

d.c.-c.t.'s at th b u d ry of th ln sid d.c s b tatio z n a s own in Fig re 10 a d 1

Oth r e uipme t s c a l n tra s, c u ln c p citors, d.c v lta e divid rs, etc c n als

b in lu e in this z n of prote tio

Is latio of a fa lte f ilter ma re uire temp rary blo kin of th af fe te p le to p rmit

dis o n ctor o eratio

If o eratio is to c ntin e af ter remo al of th fa lte d.c f ilter bra c , th s e ific tio

s o ld c n id r th in re s d d.c sid interf ere c le els e p cte , p s ible o erlo din of