Reactive power homemade

No pow­er plants, no reac­tive pow­er? A new tech­nol­o­gy from MR makes it pos­si­ble to pro­vide it in sub­sta­tions: at extra-high volt­age lev­el.

Conventional power plants are shutting down, renewables are taking over — so where will grid-stabilizing reactive power come from in the future? A new technology from Maschinenfabrik Reinhausen makes it possible to provide it in substations. And it does so at the extra-high voltage level.

You don’t always rec­og­nize rev­o­lu­tions at first glance: At the Schwan­dorf sub­sta­tion, not far from MR’s Regens­burg site, an over­sized white plug is insert­ed into a sock­et on 6 Octo­ber 2022. With this sym­bol­ic ges­ture, Tim Mey­er­jür­gens, Man­ag­ing Direc­tor of Ten­neT Ger­many, and Wil­fried Breuer, Man­ag­ing Direc­tor of MR, release the sub­station’s new MSCDN sys­tem for oper­a­tion. What the guests see dur­ing the sub­se­quent tour is part of the mod­ernization plans for the sub­sta­tion, which trans­mits elec­tric­i­ty from the extra-high volt­age lev­el to the dis­tri­b­u­tion net­works of the Upper Palati­nate admin­is­tra­tive dis­trict.

What the guests actu­al­ly saw on this day is noth­ing less than a cen­tral key to ensur­ing grid sta­bil­i­ty for the ener­gy tran­si­tion. That’s because the MSCDN plant in Schwan­dorf solves a prob­lem that has left many experts scratch­ing their heads: Where will the sta­bi­liz­ing reac­tive pow­er come from when more and more con­ven­tion­al pow­er plants are shut down? Because with­out reac­tive pow­er, most of which was pre­vi­ous­ly pro­duced by pow­er plants, major prob­lems arise. For exam­ple, when con­sumers all switch on the stove, wash­ing machine and TV at the same time in the evening and plug the e‑car into the wall­box, they put a strain on the grid.

“MR also gets its pow­er from this sub­sta­tion, so we’re dou­bly proud to con­tribute our expe­ri­ence here.”
Wil­fried Breuer, Geschäfts­führer Rein­hausen

Addi­tion­al reac­tive pow­er from the pow­er plants then bal­ances out the grid volt­age thus pre­vent­ing out­ages. Decen­tral­ized gen­er­a­tors like those in Feld­heim or Nieder­bobritzsch (read about them start­ing on page 19) do play a part in cre­at­ing a sus­tain­able grid infra­struc­ture. But if we con­sid­er the ris­ing glob­al ener­gy demand and the time required for munic­i­pal, decen­tral­ized con­cepts, dif­fer­ent tech­nolo­gies will be need­ed in the short and medi­um term to keep the grids sta­ble in this tran­si­tion phase. So who will pro­vide the required reac­tive pow­er?

Reactive power at all levels

This is what sub­sta­tions can do on their own with the help of an MSCDN sys­tem. MSCDN stands for Mechan­i­cal­ly Switched Capac­i­tor with Damp­ing Net­work. When the load is high, the sys­tem pro­vides capac­i­tive reac­tive pow­er, and when the load is low, it pro­vides pro­tec­tion against over­volt­age by auto­mat­i­cal­ly con­nect­ing and dis­con­nect­ing the com­pen­sa­tion system—which is already suf­fi­cient in many sit­u­a­tions. “New oper­at­ing equip­ment to replace the large rotat­ing gen­er­a­tors in the AC trans­mis­sion grid is essen­tial for the ener­gy turn­around,” explains Thomas Brück­n­er from MR’s Pow­er Qual­i­ty (PQ) busi­ness unit which plans and builds MSCDN plants togeth­er with OMEXOM. “Our PQ spe­cial­ists in Erfurt have already installed these sev­er­al times around the world and will also pro­vide reli­able sup­port in the trans­mis­sion grid,” says Wil­fried Breuer.

onload 12 substation schwandorf energy transition turnaround blindleistung
They stand there like a bul­wark — the units of the MSCDN sys­tem that make the sub­sta­tion fit for volt­age fluc­tu­a­tions.

This is because in recent years the experts have expand­ed the MR prod­uct port­fo­lio and fur­ther devel­oped the sys­tems so that they can also with­stand the require­ments in the trans­mis­sion net­work at high and extra-high volt­age lev­els. Breuer: “As a result, we can already imple­ment effec­tive solu­tions for volt­age reg­u­la­tion for three of the four Ger­man trans­mis­sion sys­tem oper­a­tors; such as here in Schwan­dorf, but also, for exam­ple, for Ampri­on at the Sechtem sub­sta­tion near Born­heim or for 50Hertz in Bad Lauch­städt.”

A substation for the future

As the largest of the four Ger­man trans­mis­sion sys­tem oper­a­tors, Ten­neT has already ordered three MSCDN plants from MR to mod­ern­ize the grid infra­struc­ture and ensure sta­bil­i­ty. The first of the three plants has start­ed oper­a­tion at the Schwan­dorf sub­sta­tion. It con­nects a total of four extra-high volt­age lines with the dis­tri­b­u­tion net­works and is cru­cial for sup­ply­ing the entire region. Thanks to the new plant, the region will be spared the sce­nar­ios that British reg­u­la­tors warned about in the media this year: that the col­lec­tive boil­ing of water for five o’clock tea could soon pro­voke pow­er cuts across the coun­try.

“In imple­ment­ing the ener­gy tran­si­tion, we also depend on inno­v­a­tive devel­op­ments.”
Tim Mey­er­jür­gens, Geschäfts­führer Ten­neT

That’s why Ten­neT is plan­ning even more modern­ization mea­sures in Schwan­dorf. Tim Mey­er­jür­gens, Ten­neT CEO, explains: “Every mile­stone helps us achieve the ambi­tious cli­mate pol­i­cy goals of Bavaria and inte­grate more renew­ables into the grid.” Because prob­lems also arise on the oth­er side when there is plen­ty of solar ener­gy avail­able in the sun­ny mid­day hours, but con­sumers do not need it. Ten­neT is invest­ing around 68 mil­lion euros in the project—2.5 mil­lion in MR’s MSCDN plant alone. In addi­tion, all switchgear and steel struc­tures there will be suc­ces­sive­ly dis­man­tled and rebuilt, and the site area will be expand­ed by 3,500 square meters. These and oth­er ren­o­va­tions will also help to trans­port region­al­ly pro­duced wind and solar pow­er to the con­sump­tion cen­ters.


The MSCDN sys­tem is designed as a C‑type fil­ter cir­cuit with divid­ed capac­i­tances and damp­ing resis­tance. Its choke coils are designed so effi­cient­ly that they gen­er­ate only low loss­es. The sys­tem can be phase-selec­tive­ly acti­vat­ed via a spe­cial pow­er switch. Com­plex dynam­ic sys­tems such as the STATCOM (pow­er con­vert­er) and sta­t­ic reac­tive pow­er com­pen­sators (SVC) are used for step­less con­trol.MSCDN substation energy transistion Onload

Wind farms as power plants

Renew­able gen­er­a­tors will replace con­ven­tion­al pow­er plants in their pro­duc­tion of ener­gy — but not in their func­tion as providers of reac­tive pow­er. At least not yet. Because in order to con­vert volatile gen­er­a­tors into pow­er plants, they would have to be cou­pled and equipped with a reg­u­lat­ing head sta­tion, and con­nect­ed to the grid core via a DC grid. Research projects are cur­rent­ly under­way in this regard. Read in our Impulse how wind farms could become pow­er plants.

Read more about wind farms as pow­er plants in our impulse arti­cle.

Bavaria leads the way

Ten­neT is thus sup­port­ing the plans of the Ger­man state of Bavaria to be the first cli­mate-neu­tral state in the Ger­man repub­lic by 2040. Plans that go hand in hand with TenneT’s grid expan­sion projects, as Mey­er­jür­gens reveals: “We at Ten­neT are aware of our respon­si­bil­i­ty and will there­fore invest at least 60 bil­lion euros in the ener­gy tran­si­tion by 2030.” Of this, 0.5—1.5 bil­lion per year will be spent on grid expan­sion in Bavaria alone. Wil­fried Breuer adds: “We are pleased to strength­en and con­tin­ue our coop­er­a­tion with Ten­neT TSO.”

The next MSCDN plants will soon be erect­ed at Lan­des­ber­gen in Low­er Sax­ony and at UW Wür­gau in Bavaria where MR tech­nol­o­gy is also being used in new phase-shift­ing trans­form­ers (read more about this from page 34). So things are moving—and at all lev­els. “Until just a few years ago, the big play­ers seemed quite hes­i­tant, because although it was clear for many aspects of the ener­gy tran­si­tion “what” need­ed to be done, the tech­nol­o­gy for the “how” was still lack­ing in some cas­es or was still very cost-inten­sive,” explains Brück­n­er. Breuer adds, “The more coura­geous­ly we ac­tively work togeth­er on the ener­gy tran­si­tion, the more inno­va­tions and new tech­nolo­gies will emerge pre­cise­ly as a result and pave the way—like our MSCDN sys­tems.” 


onload thomas brueckner brückner mscdn substation schwandorfDo you have any ques­tions about the project?
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