Power system distribution is changing. The increase of solar and wind power, local generation, storage and consumption thrive the demand for DC grids.
These DC grids are seen as being the enabling technology for integration of renewable energy resources. It will allow the realization of new power systems, make way for new types of distribution power networks for industrial and urban surroundings. Support to existing AC systems via active power electroncis converters remains possible.
Key technology are advanced power electronic components, power electronic converters and active system protection, that will enable DC grids on multiple voltages levels. These new power electronic components improve the overall higher performance, allow reduced costs, lower losses and smaller size in combination with more flexible functionality and reliability. It is expected that especially low voltage and medium voltage DC grids are will play a key role in stable and reliable distribution of larger power flows in future distribution DC grids.
The Active Front End can be modeled in detail with Voltage Oriented Control [VOC], controlling both P and Q simultaneously. In the simulation below a step in Q is made in the fourth period, resulting in lower currents. The DC link voltage remains constant at 700 volt.