Smart grid in real-time test: the new Dig­i­tal Grid Lab of Fraun­hofer ISE

Europe’s pow­er grids are under­go­ing a pro­found trans­for­ma­tion as part of the ener­gy tran­si­tion: from large-scale pow­er plants to dis­trib­uted, intel­li­gent­ly net­worked, dig­i­tal­ly con­trolled, low-emis­sion and diverse units. Mil­lions of small feed-in plants and stor­age facil­i­ties, new con­sumers and play­ers are enter­ing the scene, which have to be man­aged at the low­er grid lev­els. In the future, the accus­tomed high qual­i­ty of sup­ply can only be achieved with the dig­i­tal­iza­tion of the grids and intel­li­gent oper­a­tional man­age­ment con­cepts. The Fraun­hofer Insti­tute for Solar Ener­gy Sys­tems ISE has now put its new Dig­i­tal Grid Lab into oper­a­tion, where the nec­es­sary com­po­nents, grid con­trol con­cepts and oper­a­tion man­age­ment strate­gies are being tested.

“Inte­grat­ing both cen­tral­ized and fluc­tu­at­ing dis­trib­uted sys­tems and main­tain­ing grid sta­bil­i­ty is a major chal­lenge for grid oper­a­tors. With the Dig­i­tal Grid Lab, Fraun­hofer ISE is expand­ing its exper­tise in the area of grid sim­u­la­tion and can view the grid and the com­mu­ni­ca­tion with­in it in real time,” explains Prof. Christof Wit­twer, Divi­sion Direc­tor Pow­er Elec­tron­ics, Grids and Intel­li­gent Sys­tems at Fraun­hofer ISE.

Hard­ware-in-the-loop sim­u­la­tions in real time

At the heart of the new lab­o­ra­to­ry are the six pow­er­ful hard­ware-in-the-loop (HIL) com­put­ers: they allow pow­er grids with up to 2000 nodes to be mod­elled and their behav­iour to be test­ed at high tem­po­ral res­o­lu­tion. For devices or sys­tems at grid nodes, but also for self-suf­fi­cient micro grids, smart dis­tricts and dis­tri­b­u­tion grids, crit­i­cal grid sit­u­a­tions can also be sim­u­lat­ed in this state-of-the-art test envi­ron­ment with­out endan­ger­ing the real pow­er grid. Eight flex­i­bly switch­able pow­er ampli­fiers with a total out­put of 800 kVA allow this sim­u­lat­ed net­work sit­u­a­tion to be applied to a test object or bat­ter­ies and gen­er­a­tors (e.g. pho­to­volta­ic sys­tems) to be sim­u­lat­ed in hard­ware. The mod­ern infra­struc­ture allows the con­sid­er­a­tion of AC or DC networks.

“The dig­i­tal twin on the HIL com­put­er is very flex­i­ble to con­fig­ure thanks to a library of mod­els. We can sim­u­late pow­er grids of dif­fer­ent sizes and volt­age lev­els and sim­u­late both res­i­den­tial and com­mer­cial pow­er sys­tems. The twin enables the eval­u­a­tion and opti­miza­tion of com­po­nents, ener­gy man­age­ment sys­tems and com­mu­ni­ca­tion stan­dards in a safe, real­is­tic envi­ron­ment,” says Dr. Bern­hard Wille-Hauß­mann, who heads the lab­o­ra­to­ry as group man­ag­er for net­work oper­a­tion and net­work planning.

The Dig­i­tal Grid Lab is also equipped with a con­trol room in which new con­trol algo­rithms and oper­at­ing strate­gies for smart grids are test­ed using arti­fi­cial intel­li­gence meth­ods. The hard­ware-in-the-loop com­put­er takes on the role of the dig­i­tal twin here and mod­els a pow­er grid includ­ing its com­mu­ni­ca­tion for the con­trol room. This allows new con­trol con­cepts to be eval­u­at­ed in a real­is­tic envi­ron­ment under crit­i­cal con­di­tions with­out any risk to real grid operation.

Tests for intel­li­gent electromobility

The infra­struc­ture described allows the test­ing of var­i­ous ener­gy tech­nol­o­gy com­po­nents, such as bat­tery sys­tems, com­bined heat and pow­er plants or heat pumps. For the launch of the lab­o­ra­to­ry, the experts at Fraun­hofer ISE have devel­oped the dig­i­tal twin of an elec­tric vehi­cle. With this, they emu­late an elec­tric vehi­cle or even an entire vehi­cle pool with its pow­er flows and its com­mu­ni­ca­tion with the charg­ing sta­tion. In this way, dif­fer­ent types of charg­ing sta­tions can be test­ed with regard to their grid feed­back (accord­ing to grid con­nec­tion guide­lines VDE AR 4100/4105) and in inter­ac­tion with intel­li­gent meter­ing sys­tems and ener­gy man­age­ment sys­tems. In addi­tion to grid con­for­mi­ty, this also includes the adap­ta­tion of the charg­ing cur­rent to exter­nal require­ments, e.g. by the grid oper­a­tor or charg­ing sta­tion oper­a­tor. The Dig­i­tal Grid Lab allows test­ing of the grid con­for­mi­ty and com­mu­ni­ca­tion of charg­ing plugs and modes accord­ing to the IEC 62196, IEC 61851 and ISO 15118 stan­dards. The test of charg­ing sta­tions thus includes com­mu­ni­ca­tion tests for the entire sig­nal chain and eval­u­a­tions of the device behav­ior to exter­nal mar­ket and con­trol sig­nals. Since the test stand in the Dig­i­tal Grid Lab is also con­nect­ed to numer­ous real charg­ing sta­tions, the com­pat­i­bil­i­ty test­ing of charg­ing man­age­ment con­cepts can be car­ried out in a man­u­fac­tur­er-neu­tral and safe manner.

Vir­tu­al tour of the Dig­i­tal Grid Lab

Fol­low this link for a vir­tu­al tour of the Dig­i­tal Grid Lab with audio com­men­tary and infor­ma­tion on test equip­ment and opportunities.