Direct Current – Power flOws in megawatt-scale Energy gRids

The current electric energy distribution grid—based mainly on alternating current (AC)—has servedus for over a century. Transporting energy generated at large power stations over long distances to adistributed network of consumers.

It is starting to show its shortcomings due to a rise in localgeneration with renewable energy sources and the essentially direct current (DC) nature of manymodern electric loads.Modern grids need to deal with two-way energy flows, local intermittent generation fromrenewables and local energy storage in stationary batteries.

Medium voltage distribution microgridsusing DC instead of AC hold the promise to address the shortcomings of the AC main grid.There are several initiatives in low voltage secondary distribution grids, and DC-POWER is expandingtheir concepts into the medium voltage range. We propose the D 3 Bus, a bipolar DC bus operating at±1.5 kV.

Compared to standard 3-phase 400V AC distribution the D 3 Bus can reduce distributionenergy losses by over 90%, reduce downtime, equipment cost, and space requirements whileincreasing sustainability.DC-POWER demonstrates, tests and validates the D 3 Bus concept in two operational pilots: Onepowering an industrial-scale hydrogen electrolyser stack at 2 MW power, and one powering a newdata centre with up to 500 kW installed IT power.

Both pilots include sizeable solar PV arrays (200kW), while the data centre also includes a directly coupled DC UPS solution.In order to realise these pilots, DC-POWER develops several DC-DC converters, an AC activefrontend, as well as system protection components and a power/energy management system.The D 3 Bus is intended as a first stepping-stone towards standardization of MVDC distributionmicrogrids.

It is such industry-wide standards that will enable and accelerate the adaptation of theelectricity distribution system towards the energy demands of the future and net zero.