12 Power Electronics for Flexible DC Distribution Grids

• 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.

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.

peru, china, chile

Electronic Transformer

Medium-frequency transformer (500-2000 Hz)

▪ Transformer reduction of weight by factor 10

• 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€

• 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%

• 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

A DC underlay grid is an interconnected medium voltage DC grid which can be integrated in the existing high voltage AC grid

By adjusting the phase shift between primary and secondary phase voltage, the current flow and thus the power flow can be controlled

• 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)