{"id":14237,"date":"2025-07-17T15:14:16","date_gmt":"2025-07-17T13:14:16","guid":{"rendered":"https:\/\/onload.reinhausen.com\/de\/?p=14237"},"modified":"2025-07-21T09:06:58","modified_gmt":"2025-07-21T07:06:58","slug":"on-load-tap-changer-in-hvdc-systems","status":"publish","type":"post","link":"https:\/\/onload.reinhausen.com\/en\/07-2025\/on-load-tap-changer-in-hvdc-systems\/","title":{"rendered":"More efficiency for modern HVDC systems"},"content":{"rendered":"\n
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High-volt\u00adage direct cur\u00adrent (HVDC) trans\u00admis\u00adsion makes it pos\u00adsi\u00adble to trans\u00adport large amounts of ener\u00adgy \u2013 espe\u00adcial\u00adly from renew\u00adable ener\u00adgy sources \u2013 over long dis\u00adtances to con\u00adsumers with vir\u00adtu\u00adal\u00adly no loss\u00ades. To do this, con\u00advert\u00ader sta\u00adtions con\u00advert the incom\u00ading AC volt\u00adage into DC volt\u00adage at the begin\u00adning of the HVDC lines and back into AC volt\u00adage at the end. For many years, grid oper\u00ada\u00adtors relied on line-com\u00admu\u00adtat\u00aded con\u00advert\u00aders (LCC) which work with thyris\u00adtors that are depen\u00addent on the sup\u00adply volt\u00adage of the AC grid for fault-free oper\u00ada\u00adtion. This is where a reg\u00adu\u00adlat\u00aded trans\u00adformer comes into play, which con\u00adnects the con\u00advert\u00ader sta\u00adtion to the AC grid. Here, a tap-chang\u00ader reg\u00adu\u00adlates the input volt\u00adage pre\u00adcise\u00adly in dis\u00adcrete steps to ensure that the thyris\u00adtors switch in the opti\u00admum range and that the oper\u00ada\u00adtion of the con\u00advert\u00ader remains sta\u00adble.<\/p>\n\n\n\n

New converter technology<\/h2>\n\n\n\n

How\u00adev\u00ader, with the intro\u00adduc\u00adtion of con\u00advert\u00aders using volt\u00adage source con\u00advert\u00ader (VSC) tech\u00adnol\u00ado\u00adgy, the sig\u00adnif\u00adi\u00adcance of on-load tap-chang\u00aders in HVDC sys\u00adtems is chang\u00ading: this con\u00advert\u00ader tech\u00adnol\u00ado\u00adgy uses IGBTs, i.e. semi\u00adcon\u00adduc\u00adtor ele\u00adments that can switch inde\u00adpen\u00addent\u00adly and flex\u00adi\u00adbly. This means that VSC con\u00advert\u00aders can con\u00adtrol volt\u00adage and cur\u00adrent inde\u00adpen\u00addent\u00adly of the sup\u00adply volt\u00adage of the AC grid and react to fluc\u00adtu\u00ada\u00adtions in the pow\u00ader grid even with\u00adout a reg\u00adu\u00adlat\u00aded trans\u00adformer. But does this mean the end of on-load tap-chang\u00aders in mod\u00adern HVDC sys\u00adtems?<\/p>\n\n\n\n

Better switching<\/h2>\n\n\n\n

The answer is no. This is the con\u00adclu\u00adsion of an inde\u00adpen\u00addent study by TU Ilme\u00adnau, which looked at the char\u00adac\u00adter\u00adis\u00adtics of mod\u00adern HVDC sys\u00adtems. The study shows that HVDC sys\u00adtems with VSC sys\u00adtems have high\u00ader loss\u00ades when they are oper\u00adat\u00aded with\u00adout a tap-chang\u00ader in the trans\u00adformer. <\/mark>The rea\u00adson for this is the cur\u00adrent flow through the semi\u00adcon\u00adduc\u00adtor ele\u00adments, which is often high\u00ader than nec\u00ades\u00adsary with\u00adout tar\u00adget\u00aded volt\u00adage reg\u00adu\u00adla\u00adtion. The result: more heat loss and less usable ener\u00adgy. This is pre\u00adcise\u00adly where the on-load tap-chang\u00ader comes in. It increas\u00ades the volt\u00adage applied to the invert\u00ader based on the respec\u00adtive oper\u00adat\u00ading sit\u00adu\u00ada\u00adtion and in com\u00adpli\u00adance with the per\u00admis\u00adsi\u00adble sys\u00adtem lim\u00adits, and does so in such a way that the cur\u00adrent flow decreas\u00ades while the pow\u00ader remains the same.<\/p>\n\n\n\n

This sig\u00adnif\u00adi\u00adcant\u00adly reduces loss\u00ades<\/mark> and increas\u00ades the ener\u00adgy yield. This pays off, espe\u00adcial\u00adly for long trans\u00admis\u00adsion dis\u00adtances and large amounts of ener\u00adgy: More green ener\u00adgy reach\u00ades con\u00adsumers, and oper\u00ada\u00adtion becomes more effi\u00adcient and eco\u00adnom\u00adi\u00adcal<\/mark>. In addi\u00adtion, the low\u00ader ther\u00admal load reduces wear and extends the ser\u00advice life of the invert\u00ader com\u00adpo\u00adnents<\/mark>. And while these have to be replaced after around 15 years, on-load tap-chang\u00aders last up to 60 years \u2013 an invest\u00adment that pays off both eco\u00adlog\u00adi\u00adcal\u00adly and eco\u00adnom\u00adi\u00adcal\u00adly for grid oper\u00ada\u00adtors in the long term.<\/p>\n\n\n\n

Con\u00adclu\u00adsion: Tap-chang\u00aders will remain a key tech\u00adnol\u00ado\u00adgy for HVDC sys\u00adtems <\/mark>in the future because there is cur\u00adrent\u00adly no equiv\u00ada\u00adlent tech\u00adni\u00adcal solu\u00adtion for pre\u00adcise volt\u00adage reg\u00adu\u00adla\u00adtion dur\u00ading oper\u00ada\u00adtion with max\u00adi\u00admum reli\u00ada\u00adbil\u00adi\u00adty and max\u00adi\u00admum ser\u00advice life. This is why Maschi\u00adnen\u00adfab\u00adrik Rein\u00adhausen will con\u00adtin\u00adue to focus on the fur\u00adther devel\u00adop\u00adment of on-load tap-chang\u00aders for HVDC sys\u00adtems in the future \u2013 with mod\u00adern con\u00adtrol con\u00adcepts, dig\u00adi\u00adtal net\u00adwork\u00ading and the tar\u00adget\u00aded use of arti\u00adfi\u00adcial intel\u00adli\u00adgence.<\/p>\n\n\n\n

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\u201cOn-load tap-changers simplify operational management\u201d<\/h1>\n\n\n\n

Three questions for Prof. Dirk Westermann, who led the study at TU Ilmenau.<\/h3>\n\n\n
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What general trends do you see for HVDC applications?<\/strong><\/h4>\n\n\n\n

Sev\u00ader\u00adal trends can cur\u00adrent\u00adly be observed. More HVDC sys\u00adtems are need\u00aded because the expan\u00adsion of renew\u00adable ener\u00adgies is increas\u00ading, and glob\u00adal elec\u00adtric\u00adi\u00adty trad\u00ading is also grow\u00ading. In addi\u00adtion, there are con\u00adtin\u00adu\u00adous tech\u00adno\u00adlog\u00adi\u00adcal advances that are lead\u00ading to more effi\u00adcient and cost-effec\u00adtive HVDC sys\u00adtems, such as self-com\u00admu\u00adtat\u00aded mod\u00adu\u00adlar mul\u00adti\u00adlevel con\u00advert\u00aders in half- or full-bridge tech\u00adnol\u00ado\u00adgy.<\/p>\n\n\n\n

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\u201eOn-load tap-chang\u00aders do not increase the con\u00adtrol effort in the sys\u00adtem, but rather sim\u00adpli\u00adfy oper\u00ada\u00adtional man\u00adage\u00adment.\u201c<\/p>\nProf. Dirk West\u00ader\u00admann<\/cite><\/blockquote>\n\n\n\n

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Will we even need on-load tap-changers in HVDC systems in the future?<\/strong><\/h4>\n\n\n\n

Def\u00adi\u00adnite\u00adly. Although self-con\u00adtrolled invert\u00aders can take over a cer\u00adtain volt\u00adage reg\u00adu\u00adla\u00adtion func\u00adtion, tap-chang\u00aders give you the chance to imple\u00adment improved con\u00adtrol strate\u00adgies and min\u00adi\u00admize loss\u00ades.<\/p>\n\n\n\n

Don\u2019t HVDC systems become more vulnerable with additional components such as on-load tap-changers?<\/strong><\/h4>\n\n\n\n

No, because on-load tap-chang\u00aders have been tried and test\u00aded for decades and have a long ser\u00advice life and very low sus\u00adcep\u00adti\u00adbil\u00adi\u00adty to faults, espe\u00adcial\u00adly with estab\u00adlished man\u00adu\u00adfac\u00adtur\u00aders. In addi\u00adtion, on-load tap-chang\u00aders do not increase the con\u00adtrol effort in the sys\u00adtem, but rather sim\u00adpli\u00adfy oper\u00ada\u00adtional man\u00adage\u00adment.<\/p>\n\n\n\n

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Download the study<\/h3>\n\n\n\n
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Would you like to read the whole study? <\/i><\/strong> <\/a>Here you can down\u00adload it.<\/a><\/p>\n<\/div><\/div>\n\n\n\n

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YOUR CONTACT PERSON<\/h2>\n\n\n\n

Do you have ques\u00adtions about on-load tap-chang\u00aders in HVDC appli\u00adca\u00adtions? <\/strong>
Daniel Raab is here for you:
<\/i>\u2009 <\/a>D.Raab@reinhausen.com<\/a><\/p>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"

Will new con\u00advert\u00ader tech\u00adnolo\u00adgies such as volt\u00adage source con\u00advert\u00aders (VSC) make the tap-chang\u00ader in HVDC sys\u00adtems super\u00adflu\u00adous? A study by the Tech\u00adni\u00adcal Uni\u00adver\u00adsi\u00adty of Ilme\u00adnau has inves\u00adti\u00adgat\u00aded this ques\u00adtion.<\/p>\n","protected":false},"author":33,"featured_media":14245,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"wp_typography_post_enhancements_disabled":false,"footnotes":""},"categories":[44,1],"tags":[],"class_list":["post-14237","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-07-2025","category-onload"],"acf":[],"_links":{"self":[{"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/posts\/14237","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/users\/33"}],"replies":[{"embeddable":true,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/comments?post=14237"}],"version-history":[{"count":5,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/posts\/14237\/revisions"}],"predecessor-version":[{"id":14690,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/posts\/14237\/revisions\/14690"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/media\/14245"}],"wp:attachment":[{"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/media?parent=14237"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/categories?post=14237"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/onload.reinhausen.com\/en\/wp-json\/wp\/v2\/tags?post=14237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}