insulation diagnosis of high voltage power cables

4
8/19/2019 Insulation Diagnosis of High Voltage Power Cables http://slidepdf.com/reader/full/insulation-diagnosis-of-high-voltage-power-cables 1/4 2007 International Conference on Solid Dielectrics, Winchester, UK, July 8-13, 2007 Insulation Diagnosis of High Voltage Power Cables E. Gulskil*, S. Meijer', P.Cichecki', J.J. Smit' P.P. Seitz2, F. Petzold3 and F. de Vries4 'Delft University ofTechnology, HV Components andPower Systems, Delft 2628CD, Mekelweg 4, The Netherlands 2 Seitz Instruments AG, Mellingerstasse 12, CH-5443 Niederrohrdorf Switzerland 3SebaKMT, Dr. Herbert Iann Str. 6, 96148 Baunach, Germany 4Nuon Tecno, Voltastraat 2, 1800 AJ Alkmaar, The Netherlands * E-mail: e.gulskigtudelft.nl Abstract: In this contribution based on field application of advanced diagnostics a systematic approach for condition assessment of HV power cables is discussed. Based on the assumption that there is not one dominant failure process in HV cable networks in addition to partial discharges dielectric diagnosis has also be included to determine the actual condition of service aged e.g. XLPE, oil-filled gas-pressurized cable insulation systems. INTRODUCTION It is known, that the insulation failures in a cable network may be caused by lower dielectric strength due to aging processes and by internal defects in the insulation system. It is known that - to reduce the failures by the aging of the impregnated insulation diagnostic methods can be used: (a) oil analysis e.g. dissolved gas analysis  DGA) (b) assessment of bulk properties of insulation e.g. tan 6 measurements [1]; - to reduce the failure by internal defects, on-site cable diagnostics can be applied based on quantities related to insulation degradation, as partial discharges. Moreover, to assess thecondition of a certain cable type tasting and diagnostic packages have to be developed. After a survey of all relevant information about the cables in the network, diagnostics are carried out to assess the condition ofeach cable [2]. Interpretation is done based on criteria for each diagnostic. All results together are used for a classification of the cable into a number of condition categories [3] see table 1. Table 1: Supported electronic file types. Condition Definition Normal No maintenance necessary Index 9 No problems Defect Short term: No impact on network initiation reliability Index 6 Long term: without any maintenance possible life time reduction Defect Short term: cable can still be operated but Index 6 the network reliability is decreased Maintenance is necessary Failure Cable can not be operated and Index 1 maintenance is necessary Based on economics repair or replacement Figure 1: Example of HV power cables diagnosis program. A maintenance program and/or guideline for further operation of the cable can be than linked to each category. Depending on the category, the condition assessment is repeated once every 3 or 5 years [4] see figure 1. HV INSULATION DIAGNOSTICS Nowadays on-site diagnostics are widely accepted and applied in the field of condition assessment of HV assets. It is know that unlike voltage testing, measurements of the dielectric may give an absolute indicator for the quality level of the cable insulation. The results of these measurements have a direct relation to the average qualitative level of the insulation at the moment of measurement and can thus be applied as a trend- or fingerprint measurement. The partial discharge diagnosis may indicate weak spots in a cable connection. In order to run the measurement partial discharges are ignited in the cable insulation or joints by the application of a test voltage [4-7]. Du e to the physical character of discharge occurrence, such as the PD inception voltage the PD pulse magnitudes, PD patterns and PD mappings for a utility interested in applying PD diagnostics for condition assessment of its power cable networks, a number of technical and economical aspects are of importance: Voltage type: equivalence in PD inception processes among different voltage stresses for solid insulating materials; 1-4244-0750-8/07/ 20.00 ©2007 IEEE. 721 Authorized licensed use limited to: Technische Universiteit Delft. Downloaded on October 10, 2008 at 05:25 from IEEE Xplore. Restrictions apply.

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Page 1: Insulation Diagnosis of High Voltage Power Cables

8/19/2019 Insulation Diagnosis of High Voltage Power Cables

http://slidepdf.com/reader/full/insulation-diagnosis-of-high-voltage-power-cables 1/4

2 0 0 7 I n t e r n a t i o n a l C o n f e r e n c e o n S o l i d D i e l e c t r i c s ,

W i n c h e s t e r ,

U K , J u l y 8 - 1 3 ,

2 0 0 7

I n s u l a t i o n

D i a g n o s i s o f High V o l t a g e

Power

C a b l e s

E .

G u l s k i l * , S .

M e i j e r ' ,

P . C i c h e c k i ' , J . J . S m i t ' P . P .

S e i t z 2 ,

F .

P e t z o l d 3 a n d F . d e

V r i e s 4

' D e l f t U n i v e r s i t y

o f T e c h n o l o g y , HV C o m p o n e n t s

a n d P o w e r S y s t e m s ,

D e l f t

2 6 2 8 C D ,

M e k e l w e g

4 ,

T h e N e t h e r l a n d s

2

S e i t z

I n s t r u m e n t s

A G ,

M e l l i n g e r s t a s s e

1 2 ,

C H - 5 4 4 3

N i e d e r r o h r d o r f

S w i t z e r l a n d

3 S e b a K M T ,

D r .

H e r b e r t

I a n n S t r .

6 , 9 6 1 4 8 B a u n a c h ,

G e r m a n y

4 N u o n

T e c n o ,

V o l t a s t r a a t

2 ,

1 8 0 0

AJ

A l k m a a r ,

T h e

N e t h e r l a n d s

*

E - m a i l :

e . g u l s k i g t u d e l f t . n l

A b s t r a c t :

I n

t h i s

c o n t r i b u t i o n b a s e d o n

f i e l d

a p p l i c a t i o n

o f

a d v a n c e d

d i a g n o s t i c s a

s y s t e m a t i c

a p p r o a c h f o r

c o n d i t i o n a s s e s s m e n t

o f

HV

p o w e r

c a b l e s

i s d i s c u s s e d .

B a s e d o n t h e a s s u m p t i o n

t h a t t h e r e i s n o t o n e d o m i n a n t

f a i l u r e

p r o c e s s

i n

HV c a b l e n e t w o r k s

i n

a d d i t i o n t o

p a r t i a l d i s c h a r g e s

d i e l e c t r i c

d i a g n o s i s

h a s a l s o b e

i n c l u d e d t o d e t e r m i n e

t h e a c t u a l c o n d i t i o n

o f s e r v i c e

a g e d e . g . X L P E , o i l - f i l l e d g a s - p r e s s u r i z e d

c a b l e

i n s u l a t i o n

s y s t e m s .

INTRODUCTION

I t i s

k n o w n , t h a t t h e i n s u l a t i o n

f a i l u r e s

i n

a c a b l e

n e t w o r k

may b e c a u s e d b y l o w e r

d i e l e c t r i c

s t r e n g t h

d u e

t o

a g i n g p r o c e s s e s

a n d

b y

i n t e r n a l

d e f e c t s

i n

t h e

i n s u l a t i o n

s y s t e m .

I t i s k n o w n

t h a t

-

t o r e d u c e t h e

f a i l u r e s

b y

t h e

a g i n g

o f t h e

i m p r e g n a t e d

i n s u l a t i o n d i a g n o s t i c

m e t h o d s c a n

b e

u s e d :

( a ) o i l

a n a l y s i s e . g .

d i s s o l v e d

g a s a n a l y s i s   D G A ) ( b )

a s s e s s m e n t

o f

b u l k

p r o p e r t i e s o f

i n s u l a t i o n

e . g .

t a n 6

m e a s u r e m e n t s [ 1 ] ;

-

t o r e d u c e

t h e

f a i l u r e

b y

i n t e r n a l

d e f e c t s ,

o n - s i t e

c a b l e

d i a g n o s t i c s

c a n

b e

a p p l i e d

b a s e d

o n

q u a n t i t i e s

r e l a t e d

t o i n s u l a t i o n

d e g r a d a t i o n ,

a s

p a r t i a l

d i s c h a r g e s .

M o r e o v e r ,

t o a s s e s s t h e c o n d i t i o n o f a

c e r t a i n

c a b l e

t y p e

t a s t i n g

a n d

d i a g n o s t i c p a c k a g e s

h a v e

t o b e

d e v e l o p e d .

A f t e r

a s u r v e y o f

a l l

r e l e v a n t

i n f o r m a t i o n

a b o u t t h e

c a b l e s

i n

t h e

n e t w o r k , d i a g n o s t i c s

a r e

c a r r i e d

o u t

t o

a s s e s s t h e c o n d i t i o n

o f e a c h

c a b l e

[ 2 ] .

I n t e r p r e t a t i o n

i s

d o n e

b a s e d o n

c r i t e r i a f o r

e a c h

d i a g n o s t i c .

A l l r e s u l t s

t o g e t h e r

a r e u s e d f o r a c l a s s i f i c a t i o n

o f

t h e c a b l e i n t o a

n u m b e r o f c o n d i t i o n

c a t e g o r i e s [ 3 ]

s e e

t a b l e

1 .

T a b l e

1 :

S u p p o r t e d

e l e c t r o n i c

f i l e

t y p e s .

C o n d i t i o n D e f i n i t i o n

N o r m a l No

m a i n t e n a n c e

n e c e s s a r y

I n d e x 9

No

p r o b l e m s

D e f e c t S h o r t

t e r m : No

i m p a c t

o n n e t w o r k

i n i t i a t i o n

r e l i a b i l i t y

I n d e x 6

L o n g

t e r m : w i t h o u t

a n y

m a i n t e n a n c e

p o s s i b l e

l i f e t i m e r e d u c t i o n

D e f e c t S h o r t t e r m : c a b l e c a n s t i l l b e

o p e r a t e d

b u t

I n d e x

6

t h e

n e t w o r k

r e l i a b i l i t y

i s d e c r e a s e d

M a i n t e n a n c e i s

n e c e s s a r y

F a i l u r e C a b l e c a n

n o t

b e

o p e r a t e d

a n d

I n d e x

1

m a i n t e n a n c e

i s

n e c e s s a r y

B a s e d

o n

e c o n o m i c s

r e p a i r

o r

r e p l a c e m e n t

F i g u r e 1 :

E x a m p l e

o f HV p o w e r c a b l e s d i a g n o s i s

p r o g r a m .

A

m a i n t e n a n c e

p r o g r a m

a n d / o r g u i d e l i n e f o r f u r t h e r

o p e r a t i o n o f

t h e c a b l e

c a n b e

t h a n l i n k e d t o

e a c h

c a t e g o r y .

D e p e n d i n g

o n

t h e

c a t e g o r y ,

t h e c o n d i t i o n

a s s e s s m e n t i s

r e p e a t e d

o n c e

e v e r y

3 o r 5

y e a r s

[ 4 ]

s e e

f i g u r e

1 .

HV

INSULATION DIA GNOSTICS

N o w a d a y s

o n - s i t e

d i a g n o s t i c s

a r e

w i d e l y

a c c e p t e d

a n d

a p p l i e d

i n

t h e f i e l d

o f

c o n d i t i o n a s s e s s m e n t

o f

HV

a s s e t s . I t i s k n o w t h a t u n l i k e

v o l t a g e t e s t i n g ,

m e a s u r e m e n t s

o f

t h e

d i e l e c t r i c

may

g i v e

a n

a b s o l u t e

i n d i c a t o r f o r t h e

q u a l i t y

l e v e l o f t h e c a b l e i n s u l a t i o n .

T h e r e s u l t s

o f

t h e s e m e a s u r e m e n t s h a v e a

d i r e c t r e l a t i o n

t o t h e

a v e r a g e q u a l i t a t i v e

l e v e l o f t h e i n s u l a t i o n a t t h e

moment

o f m e a s u r e m e n t a n d

c a n

t h u s

b e

a p p l i e d

a s

a

t r e n d -

o r

f i n g e r p r i n t

m e a s u r e m e n t .

T h e

p a r t i a l

d i s c h a r g e

d i a g n o s i s

may

i n d i c a t e

w e a k

s p o t s

i n

a c a b l e c o n n e c t i o n .

I n

o r d e r t o r u n t h e

m e a s u r e m e n t

p a r t i a l

d i s c h a r g e s

a r e

i g n i t e d

i n

t h e c a b l e i n s u l a t i o n o r

j o i n t s b y

t h e

a p p l i c a t i o n

o f

a t e s t

v o l t a g e

[ 4 - 7 ] .

Du e t o

t h e

p h y s i c a l

c h a r a c t e r

o f

d i s c h a r g e o c c u r r e n c e ,

s u c h a s

t h e

PD

i n c e p t i o n

v o l t a g e

t h e

PD

p u l s e m a g n i t u d e s ,

PD

p a t t e r n s

a n d

PD

m a p p i n g s

f o r

a

u t i l i t y

i n t e r e s t e d

i n

a p p l y i n g

PD

d i a g n o s t i c s

f o r c o n d i t i o n a s s e s s m e n t

o f

i t s

p o w e r

c a b l e

n e t w o r k s ,

a n u m b e r

o f t e c h n i c a l

a n d

e c o n o m i c a l

a s p e c t s

a r e

o f

i m p o r t a n c e :

V o l t a g e

t y p e :

e q u i v a l e n c e

i n PD

i n c e p t i o n p r o c e s s e s

a m o n g

d i f f e r e n t

v o l t a g e

s t r e s s e s

f o r

s o l i d

i n s u l a t i n g

m a t e r i a l s ;

1 - 4 2 4 4 - 0 7 5 0 - 8 / 0 7 / 2 0 . 0 0

© 2 0 0 7 I E E E .

7 2 1

Authorized licensed use limited to: Technische Universiteit Delft. Downloaded on October 10, 2008 at 05:25 from IEEE Xplore. Restrictions apply.

Page 2: Insulation Diagnosis of High Voltage Power Cables

8/19/2019 Insulation Diagnosis of High Voltage Power Cables

http://slidepdf.com/reader/full/insulation-diagnosis-of-high-voltage-power-cables 2/4

N o n - d e s t r u c t i v e n e s s : n o n - d e s t r u c t i v e n e s s

o f

v o l t a g e

s t r e s s

d u r i n g t h e

d i a g n o s i s ;

IEC 6 0 2 7 0 c o n f o r m i t y .

i n

t h e

c a s e

o f m e a s u r i n g t h e PD

q u a n t i t y a p p a r e n t c h a r g e o f

PD

p u l s e s

i n

[ p C ]

a n d

[ n C ]

t h e

PD

d e t e c t i o n

m e t h o d s a p p l i e d

h a s

t o

f u l f i l l t h e

r e c o m m e n d a t i o n

o f I E C 6 0 2 7 0 ;

S e n s i t i v i t y .

i m m u n i t y

f o r

o n - s i t e

i n t e r f e r e n c e s

a n d

t h e

l e v e l

o f

s y s t e m b a c k g r o u n d n o i s e ;

A n a l y s i s .

p o s s i b i l i t y t o

g e n e r a t e a d v a n c e d d i a g n o s t i c

i n f o r m a t i o n t o

s u p p o r t d i a g n o s t i c k n o w l e d g e r u l e s ;

E f f i c i e n c y .

i n v e s t m e n t c o s t s , m a i n t e n a n c e c o s t s ,

t r a n s p o r t a b i l i t y

a n d o p e r a t i o n

o f

t h e m e t h o d

i n

d i f f e r e n t

f i e l d

c i r c u m s t a n c e s

T h e

t a n

6 m e a s u r e m e n t i s a p p l i e d f o r t h e d e t e r m i n a t i o n

o f t h e

l o s s f a c t o r

o f t h e i n s u l a t i o n

m a t e r i a l .

T h i s f a c t o r

i n c r e a s e s

d u r i n g

t h e

a g e i n g p r o c e s s o f t h e c a b l e . T h e t a n

6 . m e a s u r e m e n t s h o u l d b e r e g a r d e d

a s

a d i a g n o s t i c

a n d / o r s u p p o r t i n g

m e a s u r e m e n t . T h e

t a n 6

v a l u e

o f a

c a b l e

i s

s t r o n g l y

i n f l u e n c e d

b y

t h e

c o m p o s i t i o n

o f t h e

c o n n e c t i o n ,

t h e

t r a c e ,

a n d

t h e d e v i a t i o n s

i n

j o i n t s

a n d

t h e a c t u a l c a b l e

t e m p e r a t u r e .

T h e

t a n 6

m e a s u r e m e n t

i s

o n l y a p p l i c a b l e

a s

t r e n d

m e a s u r e m e n t

i f

c o m p o s i t i o n

c i r c u m s t a n c e s

o f

t h e t r a c e a n d

t h e r m a l c o n d i t i o n s o f

s u c c e s s i v e m e a s u r e m e n t s

a r e

v i r t u a l l y

i d e n t i c a l . F o r HV

p a p e r

i n s u l a t e d

c a b l e s t h e t a n 6 . c a n b e

a n

i m p o r t a n t

i n d i c a t o r o f

p o s s i b l e

t h e r m a l b r e a k d o w n s

[ 9 1 0 ] .

ON SITE DIAGNOSIS OF HV POWER

CABLES

F o r a

c o m p l e t e

o n - s i t e

d i a g n o s i s o f a p o w e r c a b l e s , i t

i s

n e c e s s a r y t o e n e r g i e s

t h e

d i s c o n n e c t e d c a b l e c i r c u i t

u s i n g

e x t e r n a l

v o l t a g e

s o u r c e s

[ 1 2 ] .

I n

p a r t i c u l a r ,

t h e

d e t e c t i o n

e q u i p m e n t

e . g .

p a r t i a l d i s c h a r g e

o r d i e l e c t r i c

l o s e s c a n

b e d i r e c t l y c o n n e c t e d

t o t h e c a b l e

c o n d u c t o r s

( o r t h r o u g h

t h e

s w i t c h g e a r ) .

I n

t h i s

w a y ,

t h e

d i f f e r e n t

p h a s e s o f

t h e c a b l e c i r c u i t

c a n

b e

e n e r g i z e d

a n d

t h e t e s t

c a n

b e

p e r f o r m e d .

T h e

c a p a c i t i v e

p o w e r

P

n e e d e d

t o

s t r e s s o n - s i t e

t h e c a b l e i n s u l a t i o n

i s

d e t e r m i n e d

b y

t h e

t e s t

f r e q u e n c y f ,

t h e c a b l e

c a p a c i t a n c e

C c a b l e

a n d t h e

t e s t

v o l t a g e U t e s t .

I n

o r d e r t o

d e c r e a s e t h e

c a p a c i t i v e p o w e r

d e m a n d s f o r

e n e r g i z i n g

c a b l e s a s

c o m p a r e d

t o

5 0 H z t e s t

v o l t a g e s ,

d i f f e r e n t

e n e r g i z i n g

m e t h o d s

u s i n g s p e c i f i c

v o l t a g e s h a p e d

a n d

f r e q u e n c i e s

h a v e b e e n i n t r o d u c e d f o r

PD

d i a g n o s t i c s n o w a d a y s [ 1 ] .

F o r

t h i s

p u r p o s e ,

t o

p e r f o r m

o n - s i t e

i n

n o n - d e s t r u c t i v e

way

a d v a n c e d

d i a g n o s i s

o f

p o w e r

c a b l e

c i r c u i t s

u p

t o

2 5 0 k V

new m e t h o d

h a s

b e e n

i n t r o d u c e d

[ 1 1 ,

1 2 ] . O n e o f

t h e

m e t h o d s

u s i n g

d a m p e d

A C

v o l t a g e s

f o r d e t e c t i o n

a n d

l o c a l i z a t i o n o f

PD i n

c a b l e s i s k n o w n

a s

O s c i l l a t i n g

Wave

T e s t

S y s t e m   O W T S ) ,

[ 6 7 ]

s e e

f i g u r e

2 . F o r

t h e

g e n e r a t i o n

o f

d a m p e d

A C

  D A C )

v o l t a g e s ,

t h e

p o w e r

d e m a n d i s l o w d u e t o t h e

c h a r g i n g

t h e c a b l e

c a p a c i t a n c e

w i t h

a n

c o n t i n u o u s l y i n c r e a s i n g

DC

v o l t a g e ,

a f t e r w h i c h

t h e c a b l e

c a p a c i t a n c e

i s

s w i t c h e d

i n

s e r i e s

w i t h

l a r g e

i n d u c t a n c e , r e s u l t i n g

i n

a n

o s c i l l a t i n g

v o l t a g e

w a v e

w i t h

a

f r e q u e n c y c o m p a r a b l e

t o

p o w e r f r e q u e n c i e s .

Du e t o

a p p l i c a t i o n

t o

t h e

c a b l e

s e c t i o n o f

a

c o n t i n u o u s l y

i n c r e a s i n g

DC

v o l t a g e

s u p p l y , d i r e c t l y

f o l l o w e d

b y

a

s w i t c h i n g

a n d

o s c i l l a t i o n

p e r i o d

n o

  s t e a d y

s t a t e DC

H V

Power

C a b l e H V D i v i d e r

an d 1 5 0k V 7 H 15 0

kV

Switch

PD

a n a l y s e r I n d u c t o r U n i t

an d 150kV

H V

1

- 7 ) ,

U n i t

Source

Computer

C o n t r o l

U n i t

  i g u r e 2 : OWTS HV 1 5 0 S y s t e m f o r o n - s i t e

d i a g n o s i s o f HV p o w e r c a b l e

c i r c u i t s .

-

W e i g h t :

3 0 0 k g

-

S u p p l y

v o l t a g e :

220V

-

M a x .

l o a d a t 1 5 0 k V : 8 g F

-

O u t p u t :

DA C

v o l t a g e

1 5 0 k V ( 2 0

H z

-

5 0 0

H z )

-

T e s t

o b j e c t :

p o w e r c a b l e s : 1 0 0 m - 2 0 k m

F i g u r e

3 :

B a s i c d i a g n o s t i c

p a r a m e t e r s o f

o n - s i t e

d i a g n o s i s u s i n g D a m p e d

A C

V o l t a g e

  D A C )

c o n d i t i o n s

o c c u r

[ 1 3 ] .

T h e

t e s t

f r e q u e n c y

o f

t h e

o s c i l l a t i n g

v o l t a g e

w a v e i s

a p p r o x i m a t e l y

t h e r e s o n a n t

f r e q u e n c y

o f

t h e c i r c u i t .

U s i n g

d a m p e d A C

v o l t a g e s

o n -

s i t e PD

d i a g n o s i s ( d e t e c t i o n ,

l o c a l i z a t i o n )

a n d

t h e

m e a s u r e m e n t o f

d i e l e c t r i c l o s s e s

a t v o l t a g e

A C

f r e q u e n c i e s

b e t w e e n

2 0 H z

a n d 5 0 0 H z h a v e b e c o m e

p o s s i b l e .

D u r i n g

s e v e n

y e a r s

o f

w o r l d w i d e

a p p l i c a t i o n

o f

t h i s

m e t h o d

w i d e

r a n g e

o f

e x p e r i e n c e s

h a s b e e n

d e v e l o p e d

f o r MV

p o w e r

c a b l e s .

M o r e o v e r ,

s i n c e 2 0 0 4

t h i s

m e t h o d

i s

a l s o

a p p l i c a b l e

f o r HV

p o w e r

c a b l e s

u p

t o

2 5 0 k V .

A p p l y i n g

t h i s m e t h o d

p r o v i d e s

i n

a d d i t i o n t o

PD

d i a g n o s t i c

i n f o r m a t i o n a l s o t h e d i e l e c t r i c

l o s s e s ,

s e e

f i g u r e

3 .

Du e

t o

t h e

f a c t

t h a t

b y

u s i n g

t h i s

m e t h o d :

-

t h e

f r e q u e n c y

o f

d a m p e d

A C

v o l t a g e s

i s

i n

t h e

r a n g e

o f

7 2 2

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1

OOkV:

5 1

D Zp

 5 3 5 4p 45

  D S

( a )

( b )

F i g u r e 4 : E x a m p l e s o f DA C v o l t a g e s

a s

a p p l i e d

t o

a

2 2 0 k V p o w e r

c a b l e

s h o w i n g PD a c t i v i t y

i n

a

t e r m i n a t i o n :

( a )

PD

p a t t e r n s

a t d i f f e r e n t

v o l t a g e

l e v e l s , ( b )

M a p p i n g o f

PD

l o c a t i o n

i n

t h e

c a b l e u p t o

2 5 0 k V .

p o w e r

f r e q u e n c y

o f

a c c e p t a b l e

HV t e s t

s y s t e m s ,

-

a n u m b e r o f

p o w e r c y c l e s

i s

a p p l i e d

t o

t h e c a b l e

s a m p l e p r o v i d e i g n i t i o n

o f

PD

s o u r c e s

i n

s i m i l a r

w a y s

a s

c o m p a r e d

t o

o p e r a t i n g c o n d i t i o n s ,

t h e

PD

a c t i v i t y

c a n

b e

o n - s i t e

m e a s u r e d w i t h m u l t i p l e

u n d i s t u r b e d

s i n u s o i d a l

v o l t a g e

c y c l e s ,

s e e

f i g u r e

4 .

T h e

PD

a c t i v i t y s i g n a l s ,

i g n i t e d d u r i n g o n e

o r

m o r e

o s c i l l a t i n g

v o l t a g e w a v e s ,

a r e

d e t e c t e d b y

t h e

s y s t e m ,

w h i c h

c a n

p r o c e s s

t h e

s i g n a l s

f o r s e v e r a l

p u r p o s e s :

-

A

p h a s e - r e s o l v e d

PD

p a t t e r n c a n b e

r e s o l v e d

f r o m

m u l t i p l e

DA C s e q u e n c e s .

I n t h i s

w a y ,

p a t t e r n s c a n b e

o b t a i n e d

w h i c h

a r e

s i m i l a r t o

t h o s e

r e c o g n i z e d

u n d e r

5 0 ( 6 0 )

H z

c o n d i t i o n s

[ 1 2 ] .

-

S i n g l e

PD

p u l s e s

c a n

b e a n a l y z e d

f o r

o r i g i n a l

l o c a t i o n

b y u s i n g

t r a v e l i n g

w a v e

a n a l y s i s .

S t a t i s t i c a l

e v a l u a t i o n

o f

PD

s i g n a l s

o b t a i n e d a f t e r s e v e r a l

o s c i l l a t i n g

w a v e s c a n

b e

u s e d t o e v a l u a t e t h e l o c a t i o n

o f

d i s c h a r g e

s i t e s

i n

t h e

p o w e r

c a b l e .

A

PD

m a p p i n g

i s

c r e a t e d ,

w h i c h

s h o w s

t h e

d i s t r i b u t i o n

o f

t h e

d e t e c t e d

PD

i n

a

c a b l e

c i r c u i t ,

a s

a f u n c t i o n o f

t h e

I stspanning

 . .

x

Uo )

F i g u r e

5 :

E x a m p l e o f PD d i a g n o s i s   P D I V

>

1

x U o )

a n d

d i e l e c t r i c l o s s e s

m e a s u r e m e n t s

f r o m

0 . 3 x U o

t o

2 . 0 x U 0 .

o n a s e r v i c e a g e d

1 5 0 k V

o i l

f i l l e d p o w e r

c a b l e : 2 k m .

m a g n i t u d e o r t h e i n t e n s i t y .

T h e

d i e l e c t r i c

l o s s e s c a n b e

d e r i v e d

f r o m

t h e d e c a y

c h a r a c t e r i s t i c s

o f

t h e

o s c i l l a t i n g

v o l t a g e

w a v e .

I n

p a r t i c u l a r

c o m p a r i n g t h e v a l u e s a t

U o

a n d

2 U O

c a n

a n d

u s e d

t o e v a l u a t e

t h e o v e r - a l l i n s u l a t i o n d e g r a d a t i o n ,

s e e

f i g u r e

5 .

PRACTICAL

EX AMPL ES

P e r f o r m i n g o n - s i t e t e s t i n g / d i a g n o s i s

o f i n s t a l l e d HV

p o w e r

c a b l e

c i r c u i t

may

h a v e d i f f e r e n t

p u r p o s e s .

I n

p a r t i c u l a r

t h e f o l l o w i n g g o a l s c o u l d b e o f

i n t e r e s t :

a ) v e r i f y

t h a t

a new c i r c u i t

i n s t a l l a t i o n

o r r e p a i r e d

c i r c u i t d o e s n o t c o n t a i n

g r o s s

w o r k m a n s h i p

p r o b l e m s o r

w a s

n o t s u b j e c t t o

s e v e r e

m e c h a n i c a l

d a m a g e ;

b )

t o a s s e s t h e a c t u a l c o n d i t i o n o f a c a b l e

s y s t e m

a s a

F i g u r e

6 : PD

e v a l u a t i o n o f 5 0 k V ,

6km

l o n g s e r v i c e

a g e d p o w e r

c a b l e . F r o m t h e

PD

a n a l y s i s

p h a s e

b l u e

s h o w s

h i g h

PD

a c t i v i t y

a s

c o m p a r e d

t o

o t h e r p h a s e s

a n d

t h e

r e f e r e n c e

n o r m s .

U s i n g

PD

m a p p i n g a n a l y s i s

o f t h e

p h a s e

b l u e

t h e

PD

s o u r c e

h a s

b e e n l o c a t e d

i n

t h e

n e a r

c a b l e t e r m i n a t i o n .

7 2 3

- - - - - - - - - - - - - - - -  

- - - - - - - - - - - - - - - - - - - - - - - - - - -  

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

- - - - - - - - -- - - - - - - - - - - - -

- - - - - - - - - - -

  1

2

- , - - -

-1  

..

 

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p a r t

o f

a s s e t

m a n a g e m e n t p r o g r a m e . g .

-

t o

s u p p o r t m a i n t e n a n c e

a n d

r e p l a c e m e n t

m a n a g e m e n t o r

-

a s

a m e a n s

t o

s u p p o r t t h e o p e r a t i o n a l d e c i s i o n s e . g .

a b o u t t h e

l o a d

p r o f i l e

a s

a c c e p t a b l e

f o r

a

p a r t i c u l a r

c a b l e c o n n e c t i o n

I n

f i g u r e

6

a n d

7

e x a m p l e s

o f

m e a s u r i n g

r e s u l t s

a s

o b t a i n e d

f r o m s u c h d i a g n o s t i c t e s t s a r e s h o w n .

CONCLUSIONS

B a s e d

o n t h e r e s e a r c h

r e s u l t s

a s d i s c u s s e d

i n t h i s

c o n t r i b u t i o n t h e f o l l o w i n g c a n b e

c o n c l u d e d :

-

New a n d s e r v i c e a g e d

HV

p o w e r

c a b l e s

a r e

i m p o r t a n t a s s e t s a n d

h a v e

t o

b e

t e s t e d o n - s i t e ;

-

PD a n d d i e l e c t r i c l o s s e s d i a g n o s i s

a t

Damped A C

v o l t a g e s c a n b e u s e d f o r n o n - d e s t r u c t i v e

o n - s i t e

t e s t i n g o f

new a n d s e r v i c e a g e d p o w e r

c a b l e s ;

-

B a s e d

o n

f i e l d

e x p e r i e n c e s

a n d u s i n g

d i a g n o s t i c

d a t a

( P D ,

d i e l e c t r i c

l o s s e s )

f o r

d i f f e r e n t

t y p e s

o f

i n s u l a t i o n a n d

a c c e s s o r i e s e x p e r i e n c e n o r m s c a n

b e

e s t i m a t e d ;

-

S u c h e x p e r i e n c e

n o r m s f o r PD a n d d i e l e c t r i c l o s s e s

c a n b e u s e d t o

s u p p o r t

t h e A s s e t

M a n a g e m e n t

d e c i s i o n

p r o c e s s e s o f

HV

p o w e r

c a b l e

n e t w o r k s ;

10

 

L i

L2

L3

0 , 1

40

50 6 0 70 75 80

Voltage [k V peak]

 

( a )

 

L1

 

L2

L3

0 , 1

0 , 0 1

40 50 6 0 70

Voltage [k V peak]   b )

F i g u r e

7 :

E x a m p l e s

o f

d i e l e c t r i c

l o s s e s

d i a g n o s i s

o f

t w o s e r v i c e

a g e d

p o w e r

c a b l e s :

a )

d i e l e c t r i c l o s s e s

( t a n

6 )

a s

m e a s u r e d

o n a

4 0 y e a r s

o l d o i l

f i l l e d

p o w e r

c a b l e

l e n g t h

1 2 . 4

km

u s i n g d a m p e d

A C

v o l t a g e s ( 2 3

H z )

i n

f u n c t i o n o f

t h e t e s t

v o l t a g e u p

t o 1 . 5

U 0 ;

t h e

m e a s u r e d

v a l u e s

v a r y

b e t w e e n 0 . 3 5 0 0 a n d

0 . 6 2

3 5 x

1 0 - 4

a n d

6 2 x

1 0 - 4 )

b )

d i e l e c t r i c l o s s e s

( t a n

6 )

a s

m e a s u r e d

o n a

2 9

y e a r s

o l d

XLPE

p o w e r

c a b l e

l e n g t h

1 4 . 9

km

u s i n g

d a m p e d

A C

v o l t a g e s

( 3 0 H z )

i n

f u n c t i o n

o f

t h e t e s t

v o l t a g e u p

t o 1 . 3

U 0 ;

t h e

m e a s u r e d

v a l u e s

a r e l o w e r

t h a n

0 . 1 5 ( 1 5 x

1 0 - 4 )

REFERENCES

[ 1 ] CIGRE WG 2 1 . 0 5 , D i a g n o s t i c M e t h o d s

f o r

HV

P a p e r C a b l e s a n d A c c e s s o r i e s , E l e c t r a

N o .

1 7 6 ,

F e br u a r y 1 9 9 8

[ 2 ] W

H a u s c h i l d ,

W

S c h u f f i ,

R .

P l a t h ,

K .

P o l s t e r ,

T h e

T e c h n i q u e

o f A C O n - S i t e

T e s t i n g

o f HV C a b l e s b y

F r e q u e n c y - T u n e d

R e s o n a n t

T e s t

S y s t e m s ,

CIGRE

2 0 0 2 , paper 3 3 - 3 0 4 .

[ 3 ] E .

G u l s k i , B . Q u a k , E . R . S . G r o o t ,

Th

S t r e h l , E .

L e m k e , e t

a l

F u n d a m e n t a l

A s p e c t s o f

D a t a Q u a l i t y

f o r

HV

A s s e t C o n d i t i o n

A s s e s s m e n t , C i gr e

ELECTRA No

2 2 8 O c t o b e r 2 0 0 6

[ 4 ] E . G u l s k i , S .

M e i j e r ,

J . J . S m i t , F . d e F r e i s , H .

G e e n e ,

E . R . S .

G r o o t ,

M .

B o o n e , A .

B u n ,

C o n d i t i o n

a s s e s s m e n t a n d

AM

d e c i s i o n s u p p o r t

f o r

t r a n s m i s s i o n n e t w o r k

c o m p o n e n t s , P r o c e e d i n g s

4 1

CIGRE

2 0 0 6

S e s s i o n I n t e r n a t i o n a l C o u n c i l

o n

L a r g e

E l e c t r i c

S y s t e m s ,

2 7 t

A u g u s t

 

I S t

S e p t e m b e r ,

2 0 0 6

P a r i s ,

F r a n c e

[ 5 ] E . G u l s k i , F . J . W e s t e r ,

W

B o o n e ,

N . van S c h a i k ,

E . F . S t e e n n i s ,

E . R . S .

G r o o t ,

J .

P e l l i s , B . J .

G r o t e n h u i s ,

K n o w l e d g e

R u l e s

S u p p o r t f o r

CBM

o f

P o w e r C a b l e

C i r c u i t s ,

C i g r e P a r i s

2 0 0 2 ,

SC 1 5

paper

1 0 4

[ 6 ]

E .

G u l s k i ,

F . J .

W e s t e r ,

J . J .

S m i t ,

P . N . S e i t z a n d M

T u r n e r

A d v a n c e d

P D

d i a g n o s t i c o f

MV power

c a b l e

s y s t e m

u s i n g o s c i l l a t i n g

wave t e s t

s y s t e m ,

IEEE

E l e c t r i c a l I n s u l a t i o n

M a g a z i n e , 1 6 , 2 , 2 0 0 0 ,

p .

1 7 - 2 5

[ 7 ]

E .

G u l s k i , F . J . W e s t e r , J . J . S m i t , E . R . S .

G r o o t ,

P h .

W e s t e r ,

P . N .

S e i t z ,

T r a n s m i s s i o n Power C a b l e s

PD

D e t e c t i o n

a t

DampedAC

V o l t a g e s ,

J i c a b l e

2 0 0 3

[ 8 ]

F .

F a r n e t i ,

F .

O m b e l l o ,

E .

B e r t a n i a n d W

M o s c a ,

G e n e r a t i o n

o f

o s c i l l a t i n g

waves

f o r

a f t e r - l a y i n g

t e s t

o f

H V e x t r u d e d c a b l e

l i n k s ,

CIGRE S e s s i o n

[ 9 ]

J .

Popma

J .

P e l l i s ,

D i a g n o s t i c s

f o r

h i g h

v o l t a g e

c a b l e

s y s t e m s ,

P r o c e e d i n g s

E RA

c o n f e r e n c e o n

H i g h V o l t a g e p l a n t

l i f e e x t e n s i o n

L a b o r e l e c ,

L i n k e b e e k ,

B e l g i u m ,

2 3 - 2 4

N o v e m b e r ,

2 0 0 0

[ 1 0 ]

R .

H a r r e w i j n ,

W

D o e l a n d ,

P

v a n d e

W e e r d ,

O n -

s i t e

t a n

d e l t a measurements a s

f u n c t i o n o f

t h e

t e m p e r a t u r e

on a

1 5 0

kV

g a s p r e s s u r i s e d

c a b l e

s y s t e m , P r o c e e d i n g s

ERA

c o n f e r e n c e o n

H i g h

V o l t a g e

p l a n t

l i f e e x t e n s i o n .

L a b o r e l e c , L i n k e b e e k ,

B e l g i u m ,

2 3 - 2 4

N o v e m b e r , 2 0 0 0

[ 1 1 ]

E .

G u l s k i ,

E .

L e m k e ,

M .

G a m l i n ,

E .

G o c k e n b a c h ,

W

H a u s c h i l d ,

E .

P u l t r u m , E x p e r i e n c e s

i n

p a r t i a l

d i s c h a r g e

d e t e c t i o n

o f

d i s t r i b u t i o n

power

c a b l e

s y s t e m s .

E l e c t r a ,   I S S N

1 2 8 6 - 1 1 4 6 ) ,

3 4 - 4 3 .

[ 1 2 ]

F . J .

W e s t e r ,

C o n d i t i o n A s s e s s m e n t

o f

P o w e r

C a b l e s

U s i n g

PD

D i a g n o s i s

a t

Damped

A C

V o l t a g e s ,

ISBN

9 0 - 8 5 5 9 - 0 1 9 - 1 ,

P h D t h e s e s

TU

D e l f t ,

2 0 0 4

[ 1 3 ] F . H .

K r e u g e r ,

I n d u s t r i a l

H i g h

DC

V o l t a g e ,

D e l f t

U n i v e r s i t y

P r e s s ,

1 9 9 5

7 2 4

1

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