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© 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”
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 3 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 4 Dr. Denis Imamovic
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
=
~ =
~
=
~
= ~
= ~
= ~
= ~
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 5 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 6 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 7 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 8 Dr. Denis Imamovic
HVDC basic investigations
Exemplary test setups
Surface effects Long-term testing
Artificial protrusions
Temperature
gradient
Dielectric limits
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 9 Dr. Denis Imamovic
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
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2014-04-07 Page 10 Dr. Denis Imamovic
Innovative RIP insulator design for DCCS ±320 kV
Norm
aliz
ed e
lectr
ic f
ield
Radius
DC field distribution
AC field distribution
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 11 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 12 Dr. Denis Imamovic
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
© Siemens AG 2014. All rights reserved. © Siemens AG 2014. All rights reserved.
2014-04-07 Page 13 Dr. Denis Imamovic
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
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2014-04-07 Page 14 Dr. Denis Imamovic
Contact:
Dr. Denis Imamovic
E T TS PLM 4
Freyeslebenstraße 1
91058 Erlangen
09131-744510
