Varikonta / Dr. Ilgevicius

DETERMINATION OF LOADING CAPABILITIES

OF POWER CABLES

Page 2

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

AGENDA

1. Motivation and goals of the project

2. IEC 60287 Standard for power cable rating and its limitations

3. Application of analytical and nummerical methods for cable calculations

4. Case examples of MV and HV cable installation projects

5. Conclusions

Page 3

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Project Management,

Design&Engineering,

Commisioning and

Consulting

VARIKONTA SOLUTIONS FOR POWER

UTILITIES

Page 4

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

1. MOTIVATION AND GOALS OF THE PROJECT

Motivation / Problem:

Existing standard methods (e.g. Neher-McGrath, IEC 60287 or by G. Anders) are based on

analytical 1D formulations

Determination of the hot spots under unfavorable thermal conditions

Moisture migration

Short time overload

Induced voltage in the cable screen

Goals of the EUREKA “Poweropt”:

Algorithm for steady-state and dynamic current rating for single-core and three-core cables

under following thermal conditions:

-Cable in air

- cable in ground

-Cable in duct / pipe

Algorithm for economical optimization of cable cross section

Validation of simulation results and recommendations to LST/IEC standards

Page 5

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Project schedule and milestones:

1. MOTIVATION AND GOALS OF THE PROJECT

Page 6

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Project Partners:

UAB Varikonta – Project Coordinator/ Dr. A. Ilgevicius

Vilnius Gediminas Technical University – Project Partner/ Prof. R. Ciegis

Universität der Bundeswehr München – Project Partner/ Prof. H.D. Liess

1. MOTIVATION AND GOALS OF THE PROJECT

Page 7

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

The Neher-McGrath (IEC 60287) method is based on a thermal-electrical analogy

method. The basic idea is to subdivide the area in layers, where the heat sources are

substituted by current sources, thermal resistances by electrical resistances and thermal

capacitances by electrical capacitances.

2. IEC 60287 STANDARD FOR POWER CABLE

RATING AND ITS LIMITATIONS

3Wc 0.5Wd Wa0.5Wd Ws

Rth1

Rth2

Rth3

Rth4

Rth1

Rth1

3 3

The total Joule loss Wtotal in a cable can be

expressed as:

)1( 21 CaSCtotal WWWWW

The conductor temperature T rise above the

ambient temperature and rated current is given by:

)()1()1()5.0( 4321

2

21

2

1

2

ththdAC

thdAC

thdAC RRnWI

A

lnRWI

A

lRWI

A

lT

))(1()1(

)(5.0(

4321211

4321

ththACthACthAC

ththththdrated

RRnRRnRRR

RRRnRWTI

Page 8

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Curren adjustment factors:

with:

I’ is the permissible current under actual installation conditions,

F overall adjustment factor,

I is the base permissible current

The overall adjustment factor is:

where:

Ft is the adjustment factor to account the differences in ambient and conductor

temperatures from the base temperature,

Fth is the adjustment factor to account the differences in the soil thermal resistivity from

the base value,

Fg is the adjustment factor to account for cable grouping

FII '

gtht FFFF

2. IEC 60287 STANDARD FOR POWER CABLE

RATING AND ITS LIMITATIONS

Page 9

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Limitations of the IEC 60287:

- Modeling of ground thermal properties

- Modeling of the heat transfer in air gap

between cable and duct

- Dynamic loadability of cables

2. IEC 60287 STANDARD FOR POWER CABLE

RATING AND ITS LIMITATIONS

Page 10

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Comparision of IEC 60287 vs. nummerical Simulation

300mm2 XLPE copper cable direct burried in the ground:

Max permissible current acc. IEC 60287:

2. IEC 60287 STANDARD FOR POWER CABLE

RATING AND ITS LIMITATIONS

AAFFIFI gtht 51889,093,01626'

Page 11

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

Three different time scales are relevant:

-Real time operation (minutes) – Analytical approach

-Day-ahead planning (hours) – Analytical approach

-Grid planing (years) – Nummerical approach

A simulation tool should cover all three time scales

1. Real time operation/monitoring systems

4. ANALYTICAL AND NUMMERICAL METHODS

FOR CABLE CALCULATIONS

mn

nnnm

tTTTT expˆˆ

1

mn

nnmn

TT

TTt

ˆ

ˆln 1

22

2

1

2

lnmn

nnmn

II

IIt

Page 12

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

2. Day – ahead planning

-Predicted currents in each of three systems

- Predicted current in System 3 when System 1

is out of order and System 2 fails

System 1(380 kV) A C

B

System 2 (380 kV)

System 3 (150 kV)

4. ANALYTICAL AND NUMMERICAL METHODS

FOR CABLE CALCULATIONS

Page 13

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

3. Grid planning

4. ANALYTICAL AND NUMMERICAL METHODS

FOR CABLE CALCULATIONS

1mG G G

<1m

D2

D3

D1

D3

Page 14

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

-Cables in ducts

- Induced voltage into the screen by magnetic field from conductor

4. ANALYTICAL AND NUMMERICAL METHODS

FOR CABLE CALCULATIONS

Page 15

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

-HVDC Nordbalt Project:

-Total cable length: ca. 450 km,

Rated Power: 700 MW

System Voltage: 400 kV DC

The longest cable route of such power

rating so far.

5. REFERENCE PROJECTS

Reference: ABB/Nordbalt

Page 16

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

-110 kV cable in Klaipeda, Lypkiai

- Calculated max. permissible current:

5. REFERENCE PROJECTS

Base rated current

Page 17

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

-Fortum Waste-to-Energy Plant in Klaipeda

-10 and 6 kV cable installations in ground

and air

9 single core cables of 500mm2

from generator to the step up transformer

5. REFERENCE PROJECTS

Page 18

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

6. CONCLUSIONS

Page 19

Date: 28.05.2014 Dr. A. Ilgevicius

UAB Varikonta

6. QUESTIONS

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