Compact Systems for future HVDC applications - Siemens · 4/7/2014 · Compact Systems for future HVDC applications Author: Dr. Denis Imamovic Subject: DC Compact Switchgear ±320kV

© Siemens AG 2014. All rights reserved. Hannover Messe 2014

Compact Systems for future HVDC

applications

Dr. Denis Imamovic

Siemens Future Forum @ HANNOVER MESSE 2014

© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.

2014-04-07 Page 2 Dr. Denis Imamovic

Compact Systems for HVDC Applications

Main drivers today

Impact

• Increasing of

transmission capacities

• Efficient transmission

over long distances

• Increasing the grid

stability with new

generation structure

Main drivers today

• Space reduction

• Interconnection of Standardized HVDC Offshore Transmission Installations

• “Energiewende”



Compact Systems for HVDC Applications

Solutions

• Point-to Point connections for strengthening of

grid and transmission of RES

• Onshore applications in a Hybrid Transmission System

(OHL, underground Transmission)

• Offshore / Onshore Multiterminal HVDC Systems

• Overlay (Backbone) Grid incl. Onshore and

Offshore HVDC Systems



Towards a first

HVDC system in Germany

Korridor A

2 GW

Korridor A

2 GW

=

~

Initial Illustration: Bryan Christie Design. Source: www.entsoe.eu

Korridor G

2 GW

=

~

Korridor C

2 x 1,95 GW

=

~ =

~

=

~

= ~

= ~

= ~

= ~



Operational stresses in gas insulated systems

Why is it NOT possible to directly use existing AC systems for DC voltage?

DC insulating systems must withstand different electrical stress

compared to AC systems

Gas

Gas

Gas

Gas

Grounded Encapsulation

Current I

Stresses of insulators in

operation

Mechanical Stress

Chemical Stress

Thermal Stress

Electric Stress Impact on



N N

+ +

+

+ +

+

+ +

- -

- - -

- -

N

- -

- -

-

- -

-

Ionization Attachment

Recombination

Field emission

Drift due to electric field

Charge transport and

accumulation

Diffusion

∆T

Physical Effects influencing electric stress

Grounded Encapsulation



Transition from AC to DC electric field

1

0

1

0

1

0

1

0

AC

DC

Positive space charge

density in gas

Negative space charge

density in gas No

rma

lized

E-fie

ld

negative DC voltage negative DC voltage



HVDC basic investigations

Exemplary test setups

Surface effects Long-term testing

Artificial protrusions

Temperature

gradient

Dielectric limits



Technical challenges for DC insulators

• Development of insulator design allowing for control of physical effects,

particularly charging effects

• Development of suitable insulating material for DC gas insulated

systems

• Careful handling/drying of insulating parts and cleanliness during

assembly

• Definition of “equipment-specific” high voltage testing procedures

Siemens Approach »» Application of capacitively graded

insulator based on Resin Impregnated Paper (RIP) technology



Innovative RIP insulator design for DCCS ±320 kV

Norm

aliz

ed e

lectr

ic f

ield

Radius

DC field distribution

AC field distribution



Simulation

Effect of field grading

DC AC

Without field grading

With field grading

Po

ten

tia

l d

istr

ibu

tio

n

High voltage conductor High voltage conductor



Testing strategy

Conclusion

• Increasing of

transmission capacities

• Efficient transmission

over long distances

• Increasing the grid

stability with new

generation structure

There are NO international agreed standards

for this kind of equipment.

List of the possible dielectric tests:

• DC withstand test at higher level

• DC voltage with superimposed impulse

voltage

• Polarity reversal

• Long(er) term test with specified voltage,

current, temperature and time profile



Summary

In addition to traditional Central Power Generation Large Scale Renewable Energy Sources

(RES) have to be implemented into Transmission Systems

• New Transmission Solutions are needed

• Standardization of HVDC Grids has started in Europe

• Compact Gas Insulated Systems for HVDC Applications

are feasible and ready for use



Contact:

Dr. Denis Imamovic

E T TS PLM 4

Freyeslebenstraße 1

91058 Erlangen

09131-744510

[email protected]

Documents

Compact Systems for future HVDC applications - Siemens · 4/7/2014 · Compact Systems for future HVDC applications Author: Dr. Denis Imamovic Subject: DC Compact Switchgear ±320kV