MITNETZ STROM digitizes

How’s the trans­former? The grid oper­a­tor MITNETZ STROM wants to know exact­ly and is equip­ping two pow­er trans­form­ers at the Meusel­witz sub­sta­tion with ETOS®. With this cen­tral con­trol and mon­i­tor­ing sys­tem, the con­di­tion of trans­form­ers can be con­tin­u­ous­ly mon­i­tored, and their ser­vice life increased through pre­dic­tive main­te­nance.


Some­times it’s the lit­tle things that get on your nerves. For Jan Schön­feld, Asset Man­ag­er at MITNETZ STROM, and his col­leagues at the Meusel­witz sub­sta­tion in Thuringia, it was the pro­tec­tive devices on two pow­er trans­form­ers that kept tripping–seemingly for no reason–during the sum­mer months. All attempts to get to the bot­tom of the prob­lem failed.

“The trip­ping has no effect on the pow­er sup­ply,” explains Jan Schön­feld, but adds “While the trans­former con­tin­ues to run despite irreg­u­lar­i­ties, we of course still have to inves­ti­gate such mal­func­tions.” When Maschi­nen­fab­rik Rein­hausen pre­sent­ed the ETOS® sys­tem to him in the fall of 2023, it came at just the right time. The abil­i­ty to quick­ly locate irreg­u­lar­i­ties with the help of sen­sor-based, real-time mon­i­tor­ing of trans­form­ers awak­ened his hopes of being able to get to the bot­tom of prob­lems with­out much effort in the future. It soon became clear that this is by no means the only advan­tage offered by ETOS®.

“The feed-in of renew­able ener­gies, the increas­ing demand for elec­tric­i­ty for the charg­ing infra­struc­ture of elec­tric vehi­cles or new heat­ing sys­tems often exceed the capac­i­ty of our trans­form­ers.”

Jan Schön­feld, Asset Man­ag­er at MITNETZ STROM.

A Digital Twin for the Transformer

ETOS®–an open sys­tem solu­tion for pow­er transformers–enables the intel­li­gent real-time mon­i­tor­ing of oper­a­tion as well as the con­trol of pow­er trans­form­ers. Sen­sors on the trans­former col­lect all rel­e­vant oper­at­ing data, which is then eval­u­at­ed by the CPU in the ETOS® con­trol cab­i­net. This also allows main­te­nance work to be planned in a tar­get­ed man­ner. “ETOS® serves as a data source for imple­ment­ing a dig­i­tal twin of the pow­er trans­former, so to speak,” sum­ma­rizes Chris­t­ian Hofmeis­ter, Project Man­ag­er Ser­vice Solu­tions.

This was fas­ci­nat­ing to Jan Schön­feld and his col­leagues, and togeth­er with MR they launched a trans­former ser­vice project at the Meusel­witz sub­sta­tion: two trans­form­ers that con­vert the 110 kV of the high-volt­age grid into 20 kV for the medi­um-volt­age grid were equipped with intel­li­gent sen­sors and the exist­ing motor dri­ves were replaced with two intel­li­gent ETOS® dri­ve cab­i­nets.

Two trans­form­ers, which con­vert the 110 kV of the high-volt­age grid into 20 kV for the medi­um-volt­age grid, were equipped with intel­li­gent sen­sors before the ETOS® con­trol cab­i­nets were installed.

The MR team pre­pared every step of the retro­fit in advance.

Good Care, Long life

MITNETZ STROM is the largest dis­tri­b­u­tion grid oper­a­tor in east­ern Ger­many. The elec­tric­i­ty grid has a length of almost 72,000 kilo­me­ters, spread over an area of more than 29,000 square kilo­me­ters and the com­pa­ny sup­plies around 2.2 mil­lion peo­ple in Bran­den­burg, Sax­ony, Sax­ony-Anhalt and Thuringia with ener­gy. MITNETZ STROM is a whol­ly-owned sub­sidiary of envia Mit­teldeutsche Energie AG, which in turn belongs to the EON Group.

“We are strug­gling with the same prob­lems that are affect­ing the entire indus­try,” says Jan Schön­feld: “The feed-in of renew­able ener­gies, the increas­ing demand for elec­tric­i­ty for the charg­ing infra­struc­ture of elec­tric vehi­cles, new heat­ing sys­tems and the ever-increas­ing ener­gy require­ments of data cen­ters often exceed the capac­i­ty of our trans­form­ers.” And the trans­form­ers at MITNETZ STROM, as in the rest of Ger­many, are often get­ting on in years.

“Trans­form­ers have an aver­age life expectan­cy of around 50 years,” explains Schön­feld and adds: “We have a whole range of years of con­struc­tion in our 250 or so trans­form­ers. Some date back to the 1970s, oth­ers we have already replaced as part of the grid expan­sion. How­ev­er, we are always keen to keep trans­form­ers con­nect­ed to the grid for as long as pos­si­ble.” The rea­sons for this are obvi­ous: deliv­ery times for new trans­form­ers are cur­rent­ly sev­er­al years and prices have gone through the roof. At the same time, the prices for mon­i­tor­ing sys­tems have fall­en sig­nifi­cant­ly. “In addi­tion, retrofit­ting with elec­tron­ics and sen­sors is much less expen­sive than dis­man­tling and remov­ing an old trans­former and installing a new one,” says Schön­feld.

“The demands on the ETOS® sys­tem can vary depend­ing on the work­load, which is why we design each cab­i­net indi­vid­u­al­ly.”

Chris­t­ian Hofmeis­ter, Project Man­ag­er Ser­vice Solu­tions at MR.

It contains everything you need

The ETOS® sys­tem has a mod­u­lar struc­ture, as Chris­t­ian Hofmeis­ter explains: “It is impor­tant to us that cus­tomers get exact­ly the func­tions they need. Depend­ing on the work­load, the demands on the sys­tem can vary, which is why we design each cab­i­net indi­vid­u­al­ly.” The two trans­form­ers for the Meusel­witz sub­sta­tion, for exam­ple, were equipped with sen­sors for bush­ing monitoring–after all, defec­tive bush­ings are respon­si­ble for 17 per­cent of all trans­former fail­ures. “Tem­per­a­ture man­age­ment is also car­ried out by ETOS®, which con­tin­u­ous­ly deter­mines and records the wind­ing tem­per­a­ture. This makes it pos­si­ble to min­i­mize the hot-spot tem­per­a­ture at an ear­ly stage,” explains Hofmeis­ter.

For opti­mized cool­ing, the MR experts net­worked the exist­ing cool­ing sys­tem con­trol cab­i­nets with the ETOS® dri­ve cab­i­nets. “Based on the mea­sured val­ues, we can start pre-cool­ing at a cer­tain load cur­rent val­ue,” says Hofmeis­ter. Elec­tron­ic dehu­mid­i­fiers will also reduce main­te­nance costs in future.

“Pre­vi­ous­ly, our main­te­nance staff had to replace the sil­i­ca gel beads every six months,” says Schön­feld and explains, “This is no longer nec­es­sary because the new dehu­mid­i­fiers dry the sil­i­ca gel beads auto­mat­i­cal­ly on a cycli­cal basis.” The so-called VAM sen­sor for vibro-acoustic mea­sure­ments in the on-load tap-chang­er was also very impor­tant to Schön­feld and his team. “It records the vibra­tions dur­ing the switch­ing process­es and com­pares them with stored ref­er­ence val­ues,” says Schön­feld. “An alarm is trig­gered in the event of devi­a­tions.” The advan­tage: no time-con­sum­ing removal of the on-load tap-chang­er is nec­es­sary, and an analy­sis ser­vice pro­vides a detailed report with rec­om­men­da­tions and mea­sures to rec­ti­fy the irreg­u­lar­i­ty. “That’s exact­ly what I was look­ing for,” says Schön­feld with sat­is­fac­tion.

Two intel­li­gent ETOS® con­trol cab­i­nets replace the old motor dri­ves.

Ready for the future: it took just five days to set up and com­mis­sion the ETOS® con­trol cab­i­nets.

With Individuality, Expertise and Care

In order to design the ETOS® dri­ve cab­i­nets for MITNETZ STROM, Chris­t­ian Hofmeis­ter dug deep into the cir­cuit dia­grams, the trans­former data and the ven­ti­la­tion con­trol data. “Of course, you can expect exper­tise from a mar­ket leader like MR,” says Schön­feld, but adds, impressed. “Our con­tacts are often employ­ees from sales depart­ments which makes every­thing more com­pli­cat­ed because infor­ma­tion always goes via detours to the real experts. How­ev­er, we com­mu­ni­cat­ed with Chris­t­ian Hofmeis­ter direct­ly and at eye lev­el and he real­ly looked at every wiring, every cross-sec­tion, all con­nec­tions and cable bush­ings as well as all inter­faces in detail.” Schön­feld also liked the uncon­ven­tion­al but time-sav­ing way of find­ing solu­tions via vir­tu­al meet­ings and a cell phone cam­era: “Instead of hav­ing a cum­ber­some meet­ing on site, a col­league went out to the trans­form­ers with a cell phone to show the MR experts the local con­di­tions.”

Into the future in fice days

It took just five days to set up and com­mis­sion the ETOS® dri­ve cab­i­nets. “Two weeks before we start­ed, I pre­pared and reviewed all the com­mis­sion­ing doc­u­ments,” says Hofmeis­ter. In a meet­ing, he then care­ful­ly briefed all the ser­vice tech­ni­cians and went through every step of the con­ver­sion with them. He was on site him­self for the com­mis­sion­ing. “Now I know the trans­form­ers in Meusel­witz inside and out,” he says with a grin. A new era is begin­ning for the team at the Meusel­witz sub­sta­tion, and their ETOS® dri­ve cab­i­nets are the pilot for oth­er MITNETZ STROM sub­sta­tions. And Jan Schön­feld is opti­mistic. “In the future, trans­former faults can be detect­ed and rec­ti­fied at an ear­ly stage, which will hope­ful­ly put an end to unplanned main­te­nance work on Sun­day evenings,” he says.

Reinhausen Inside

The open ETOS® oper­at­ing sys­tem is easy and intu­itive to use. MR also offers prac­tice-based online train­ing cours­es for begin­ners and advanced tech­ni­cians who are entrust­ed with the com­mis­sion­ing or use of ETOS®. The free live train­ing cours­es each focus on a spe­cif­ic top­ic, which expe­ri­enced train­ers explain in a com­pact for­mat.


YOUR CONTACT PERSON

Do you have any ques­tions about the retro­fit project? Bas­t­ian Auer­bach is there for you:
B.Auerbach@reinhausen.com


Share with your network!

Never miss an issue again!

Click here to subscribe for free.