The light stays on!

OFFSHORE CABLE TESTING

They are grow­ing in num­ber and get­ting big­ger and big­ger: Off­shore wind parks make a sig­nif­i­cant con­tri­bu­tion to increas­ing the pro­por­tion of envi­ron­men­tal­ly friend­ly elec­tric­i­ty in the ener­gy mix. At the same time, the gen­er­a­tive per­for­mance of wind tur­bines is con­stant­ly increas­ing. For new wind parks, for exam­ple, the oper­at­ing volt­age of the con­nec­tion cables from the wind tur­bines to the col­lec­tion and con­nect­ing plat­forms is now being increased to 66 kV.

The experts at the Inter­na­tion­al Elec­trotech­ni­cal Com­mis­sion (IEC) there­fore decid­ed to per­mit — in addi­tion to the SOAK test (a 24-hour test at nom­i­nal volt­age) — only res­o­nance test­ing for oper­at­ing volt­ages greater than 36 kilo­volts in the new stan­dard IEC 63026 for sub­ma­rine cables up to 72.5 kV.

HIGHVOLT is the only provider of a test­ing sys­tem that is weath­er-proof and there­fore always avail­able off­shore despite adverse con­di­tions.

MOBILE CABLE TESTING

HIGHVOLT is a pio­neer when it comes to test­ing cables based on poly­mer insu­lat­ing mate­ri­als, such as cross-linked poly­eth­yl­ene (XLPE) in high-volt­age appli­ca­tions. The engi­neers from Dres­den built the first-ever mobile test­ing sys­tem, which fits on a semi truck trail­er. It can there­fore be trans­port­ed to almost any loca­tion with­out spe­cial per­mits, even where there is no space for large test­ing sys­tems.

This includes cities and dense­ly pop­u­lat­ed regions where more and more cables are being rout­ed under­ground. The test­ing trail­er is designed for cable lengths of up to 10 kilo­me­ters; for longer cables, mul­ti­ple test­ing sys­tems can also be con­nect­ed in par­al­lel and in series.

HEALTH CHECK 120 M ABOVE THE GROUND

Mechan­i­cal vibra­tions of the rotors, light­ning strikes, fre­quent load changes and a high num­ber of switch­ing oper­a­tions — the trans­form­ers in the nacelles of wind tur­bines are exposed to enor­mous loads. If they fail, it is a time-inten­sive and cost­ly feat to repair or even replace them.

What can be done? Ide­al­ly, check the trans­form­ers reg­u­lar­ly in order to iden­ti­fy impend­ing dam­age at an ear­ly stage. The stan­dard method for doing this is the induced volt­age test with par­tial dis­charge diag­nos­tics. But how does that work at more than a hun­dred meters above the ground, with lit­tle space in the nacelle? HIGHVOLT has devel­oped a portable test­ing sys­tem that oper­a­tors or ser­vice providers can use to inspect the con­di­tion of the trans­former insu­la­tion direct­ly in the nacelle itself.

XXL REACTORS FOR THE BACKBONE OF THE ENERGY TRANSITION

Renew­able ener­gy sources are often far away from pop­u­lat­ed areas. Ever larg­er dis­tances need to be trav­eled to trans­port the elec­tric­i­ty to where it is need­ed. Projects with sub­ma­rine and land cables of sev­er­al hun­dred kilo­me­ters are there­fore increas­ing around the globe. Promi­nent projects include the A‑Link, Südlink and SüdostLink in Ger­many, which form the back­bone of the ener­gy tran­si­tion.

The cable sec­tions must be test­ed in advance so that noth­ing goes wrong when oper­at­ing these cable sys­tems. The num­ber one fail­ure source are the joints that con­nect the cable sec­tions to each oth­er. Since con­ven­tion­al test­ing sys­tems soon fall short in test­ing pow­er, HIGHVOLT devel­oped spe­cial XXL reac­tors. They pro­vide four times as much pow­er at only twice the vol­ume of pre­vi­ous reac­tors for the res­o­nance test­ing method. The pow­er can be fur­ther increased through series and par­al­lel con­nec­tion, mean­ing that cable lengths of up to 200 kilo­me­ters can be test­ed.

OPERATION AT THE HEART OF THE ENERGY SUPPLY

Pow­er trans­form­ers are reach­ing a crit­i­cal age around the world, and at the same time, pow­er grid loads are increas­ing due to bidi­rec­tion­al load flows caused by the sup­ply of renew­able ener­gies. Oper­a­tors can check whether the equip­ment needs ser­vic­ing with tests such as the induced volt­age test and loss mea­sure­ments in a no-load state and under load.

Often, this neces­si­tates dis­man­tling the pow­er trans­former, drain­ing the oil and then trans­port­ing it to a repair site — at sig­nif­i­cant logis­ti­cal effort and expense. How­ev­er, there’s an eas­i­er way.

HIGHVOLT has devel­oped a test­ing sys­tem for this pur­pose that can be trans­port­ed on a semi truck trail­er, enabling this kind of high-volt­age test­ing right in the pri­ma­ry sub­sta­tion. This way, the oper­a­tor can decide based on the mea­sure­ments whether removal is even nec­es­sary, or if cheap­er on-site repairs will suf­fice.

BIG BROTHER IN THE CABLE DUCT

When mal­func­tions occur dur­ing oper­a­tion, the HiRES Loca­tor can help. This online mea­sur­ing device is con­nect­ed to medi­um- and high-volt­age cables dur­ing oper­a­tion and locates a break­down in real time, imme­di­ate­ly rais­ing an alarm.

As a result, oper­a­tors know where they have to fix the prob­lem. Con­ven­tion­al test­ing meth­ods, in con­trast, the fault is only locat­ed once the mal­func­tion has occurred. Then, after the event, a suit­able, pow­er­ful volt­age source must be brought to the cable and mea­sure­ments made in a cost­ly and time-inten­sive pro­ce­dure. The HiRES Loca­tor is there­fore a cost-effec­tive solu­tion for mon­i­tor­ing cable sec­tions in real time.