How should we cope with this ultra high
scale of decentralized and volatile
generation?
Invest in Flexible Electrical Grids and ICT to
enable Demand Side Management & (all sorts of) Energy Storage
This will require DC technology, because it is
more efficient, more reliable, more flexible and
a lot cheaper to link grids and prosumers.
Why is DC cheaper?
Because it saves a lot of copper and iron...
It is expected that price of silicon will keep going down while price of metals, in particular copper price will be increasing.
copper mines
peru, china, chile
Which power electronic topology is required and
how can it help to save material?
Electronic Transformer
Medium-frequency transformer (500-2000 Hz)
▪ Transformer reduction of weight by factor 10
costs of
Multi-terminal HVDC (Overlay Grid) with Standard AC Collector Fields and AC Grid
Multi-terminal HVDC with Medium-Voltage DC Collector Field and DC Grids
Renewables will require 17,8 Mton Cu & Fe at cost of 142 B€
Renewables will require 9,1 Mton Cu & Fe at cost of 73 B€
Why is DC more efficient?
AC Collector Fields and AC Grid: Conversion losses for off-shore ca. 11%
DC Collector Field and DC Grids: Conversion losses for off-shore ca. 5%
Why is DC more flexible?
Power flow in AC grids is controlled by voltage amplitude and phase
Unwanted Power Flow
Reactive Currents
Power flow in DC grids depend only on voltage
DC current follows voltage and path of lowest resistance
DC underlay grid
A DC underlay grid is an interconnected medium voltage DC grid which can be integrated in the existing high voltage AC grid
How can the power flow be controlled in a dual active bridge?
By adjusting the phase shift between primary and secondary phase voltage, the current flow and thus the power flow can be controlled
Name advantages of a dual-active bridge over a common 50 Hz-transformer
The production of a dual-active bridge saves resources
A dual-active bridge has a better weight-to-power ratio
The transformer can be designed smaller due to a higher frequency (>> 50 Hz)
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