{"id":14728,"date":"2025-12-16T15:46:26","date_gmt":"2025-12-16T14:46:26","guid":{"rendered":"https:\/\/onload.reinhausen.com\/de\/?p=14728"},"modified":"2025-12-16T15:46:26","modified_gmt":"2025-12-16T14:46:26","slug":"pv-systems-with-regulated-inverter-and-grid-connection-transformers","status":"publish","type":"post","link":"https:\/\/onload.reinhausen.com\/en\/12-2025\/pv-systems-with-regulated-inverter-and-grid-connection-transformers\/","title":{"rendered":"Simply regulated"},"content":{"rendered":"\n
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The demand for elec\u00adtric\u00adi\u00adty is grow\u00ading world\u00adwide, and in response, solar pow\u00ader plants are spring\u00ading up in sun\u00adny regions around the globe. Tens of thou\u00adsands of medi\u00adum-sized and large PV sys\u00adtems (pho\u00adto\u00advolta\u00adic sys\u00adtems) are already pro\u00adduc\u00ading afford\u00adable solar pow\u00ader today, and thou\u00adsands more are planned for the next \ufb01ve years. Waqas Hus\u00adsain, Glob\u00adal Account Man\u00adag\u00ader at Rein\u00adhausen, is par\u00adtic\u00adu\u00adlar\u00adly sur\u00adprised by one thing: \u201cAlthough the VRDT (volt\u00adage reg\u00adu\u00adlat\u00aded dis\u00adtri\u00adb\u00adu\u00adtion trans\u00adformer) offers impres\u00adsive advan\u00adtages, espe\u00adcial\u00adly in com\u00adbi\u00adna\u00adtion with invert\u00aders, it is still large\u00adly unknown in this area of appli\u00adca\u00adtion.\u201d<\/p>\n\n\n\n

Before join\u00ading Rein\u00adhausen, Hus\u00adsain spent \ufb01ve years in the Mid\u00addle East as a project devel\u00adop\u00ader for medi\u00adum-sized and large PV sys\u00adtems as well as rooftop sys\u00adtems in the com\u00admer\u00adcial, indus\u00adtri\u00adal, and pri\u00advate sec\u00adtors. In many projects, volt\u00adage \ufb02uc\u00adtu\u00ada\u00adtions and strict grid codes were two of the chal\u00adlenges, but the focus of opti\u00admiza\u00adtion was exclu\u00adsive\u00adly on the DC side of the sys\u00adtem, recalls the PV spe\u00adcial\u00adist, adding: \u201cThe fact that many prob\u00adlems in PV sys\u00adtems can be solved cost-effec\u00adtive\u00adly and reli\u00adably with a reg\u00adu\u00adlat\u00aded invert\u00ader sta\u00adtion trans\u00adformer is still large\u00adly unknown in the PV indus\u00adtry. I want to change that!\u201d<\/p>\n\n\n\n

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A regulated transformer gets more out of solar systems:<\/h3>\n\n\n\n
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<2<\/strong><\/h2>\n\n\n\n
year amortization period*<\/h5>\n<\/div>\n\n\n\n
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~3.5%<\/strong><\/h2>\n\n\n\n
increase in annual production*<\/h5>\n<\/div>\n\n\n\n
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8%<\/strong><\/h2>\n\n\n\n
fewer inverters needed*<\/h5>\n<\/div>\n<\/div>\n\n\n\n
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* The fig\u00adures are based on the case study con\u00adduct\u00aded by the Tech\u00adni\u00adcal Uni\u00adver\u00adsi\u00adty of Braun\u00adschweig.<\/p>\n<\/div><\/div>\n\n\n\n

2100 TWH solar power<\/h2>\n\n\n\n

PV has become the dri\u00adving force behind the glob\u00adal ener\u00adgy tran\u00adsi\u00adtion and is the fastest-grow\u00ading ener\u00adgy source. This is also the opin\u00adion of the spe\u00adcial\u00adists at Ember, one of the lead\u00ading think tanks spe\u00adcial\u00adiz\u00ading in research into the ener\u00adgy tran\u00adsi\u00adtion. Accord\u00ading to their sur\u00adveys, the amount of solar pow\u00ader gen\u00ader\u00adat\u00aded has dou\u00adbled in just three years and sup\u00adplied over 2100 ter\u00adawatt hours to pow\u00ader grids world\u00adwide in 2024. As Hus\u00adsain knows from his own expe\u00adri\u00adence, devel\u00adop\u00aders and oper\u00ada\u00adtors of medi\u00adum-sized and large PV sys\u00adtems world\u00adwide face the same prob\u00adlem: even state-of-the-art invert\u00aders reach their lim\u00adits when grid volt\u00adage or solar radi\u00ada\u00adtion \ufb02uc\u00adtu\u00adates and strict grid codes must still be met. In most cas\u00ades, this prob\u00adlem is solved by installing addi\u00adtion\u00adal invert\u00aders or using addi\u00adtion\u00adal com\u00adpen\u00adsa\u00adtion sys\u00adtems for reac\u00adtive pow\u00ader. \u201cThis is cost\u00adly and leads to greater loss\u00ades, because the sys\u00adtem can no longer deliv\u00ader its full out\u00adput, and yield is lost,\u201d explains PV spe\u00adcial\u00adist Hus\u00adsain.<\/p>\n\n\n\n

This is exact\u00adly where ECOTAP\u00ae<\/sup> VPD\u00ae<\/sup> comes in: a com\u00adpact, reg\u00adu\u00adlat\u00aded on-load tap-chang\u00ader (OLTC) locat\u00aded direct\u00adly in the trans\u00adformer between the invert\u00ader and the medi\u00adum-volt\u00adage grid or between the invert\u00ader and the pow\u00ader trans\u00adformer. Its task is as sim\u00adple as it is effec\u00adtive: the volt\u00adage on the low-volt\u00adage side is sta\u00adbi\u00adlized and the invert\u00aders can main\u00adtain their rat\u00aded pow\u00ader even when the medi\u00adum-volt\u00adage grid is \u201cwig\u00adgling.\u201d The invert\u00ader is effec\u00adtive\u00adly decou\u00adpled from the \ufb02uc\u00adtu\u00ada\u00adtions on the grid side, and a more sta\u00adble volt\u00adage pre\u00advails at the invert\u00ader lev\u00adel, which can be reg\u00adu\u00adlat\u00aded with\u00adin a range of plus\/minus two per\u00adcent. Since invert\u00aders are cer\u00adti\ufb01ed for at least plus\/minus ten per\u00adcent, the oper\u00adat\u00ading point can be adjust\u00aded dynam\u00adi\u00adcal\u00adly. <\/p>\n\n\n\n

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\u201cWith a reg\u00adu\u00adlat\u00aded invert\u00ader sta\u00adtion trans\u00adformer, we reduce shut\u00addowns, min\u00adi\u00admize pow\u00ader loss\u00ades, and ensure bet\u00adter uti\u00adliza\u00adtion of the invert\u00aders.\u201d<\/p>\nWaqas Hus\u00adsain, Glob\u00adal Account Man\u00adag\u00ader, Rein\u00adhausen<\/cite><\/blockquote>\n\n\n\n

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Hus\u00adsain explains: \u201cThis allows us to increase the volt\u00adage sup\u00adply to the invert\u00ader at peak times and increase the pow\u00ader through\u00adput, there\u00adby reduc\u00ading clip\u00adping loss\u00ades. In times of low irra\u00addi\u00ada\u00adtion, we can sig\u00adni\ufb01\u00adcant\u00adly expand the DC-MPP range, i.e. the range in which the invert\u00ader oper\u00adates opti\u00admal\u00adly.\u201d The result is that vir\u00adtu\u00adal\u00adly no under\u00advolt\u00adage aris\u00ades, which means that up to ten per\u00adcent few\u00ader invert\u00aders with asso\u00adci\u00adat\u00aded cabling and trans\u00adform\u00aders are need\u00aded to meet grid code require\u00adments and pro\u00advide the same active and reac\u00adtive pow\u00ader from the invert\u00aders. On the oth\u00ader hand, there is no longer over\u00advolt\u00adage, so the high\u00adest pow\u00ader is always achieved.<\/p>\n\n\n\n

Study verifies benefits<\/h2>\n\n\n\n

Over\u00adall, this leads to high\u00ader ener\u00adgy yields, as deter\u00admined by the Tech\u00adni\u00adcal Uni\u00adver\u00adsi\u00adty of Braun\u00adschweig in a case study. With the help of the DigSI\u00adLENT Pow\u00ader Fac\u00adto\u00adry, the effects of on-load tap switch\u00ading on the annu\u00adal yield of a 105 MVA plant in El Paso, Texas, were sim\u00adu\u00adlat\u00aded. The study, based on a project design with a DC\/AC ratio of 1.25, shows that this approach leads to sig\u00adni\ufb01\u00adcant\u00adly low\u00ader invest\u00adment costs for invert\u00aders or cabling, for exam\u00adple.<\/p>\n\n\n\n

At the same time, the addi\u00adtion\u00adal yield is around 10 GWh, which cor\u00adre\u00adsponds to approx\u00adi\u00admate\u00adly +3.5 % of annu\u00adal pro\u00adduc\u00adtion. The pay\u00adback peri\u00adod for the invest\u00adment costs for the OLTC is less than two years\u2013with a plant life of 25 to 30 years. An alter\u00adna\u00adtive design, which con\u00adsid\u00adered the use of high\u00ader-rat\u00aded 4.6 MVA invert\u00aders (oper\u00adat\u00ading at 690 V) with an OLTC instead of 4.2 MVA cen\u00adtral invert\u00aders (oper\u00adat\u00ading at 630 V) typ\u00adi\u00adcal\u00adly used in the region, showed that the same plant per\u00adfor\u00admance and yield could be achieved while using up to 8% few\u00ader invert\u00aders.<\/p>\n\n\n\n

The ECOTAP\u00ae<\/sup> VPD\u00ae<\/sup> offers a sim\u00adple but effec\u00adtive solu\u00adtion to a prob\u00adlem that every PV plant faces: volt\u00adage \ufb02uc\u00adtu\u00ada\u00adtions. The com\u00adbi\u00adna\u00adtion of high\u00ader yield, reduced invest\u00adment costs, and sta\u00adble grid qual\u00adi\u00adty makes it a tool that is like\u00adly to be used in more and more PV projects world\u00adwide in the future.<\/p>\n\n\n\n

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Studie zum Download<\/h4>\n\n\n\n

<\/i><\/strong> You can down\u00adload the case study from the Tech\u00adni\u00adcal Uni\u00adver\u00adsi\u00adty free of charge here.<\/a><\/p>\n<\/div><\/div>\n\n\n\n

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All the important information at a glance<\/h3>\n\n\n\n
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Grid Codes: grid-compliant integration of renewable energies<\/h3>\n\n\n\n
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With the increas\u00ading share of renew\u00adable ener\u00adgies<\/strong>, com\u00adpli\u00adance with grid codes is becom\u00ading increas\u00ading\u00adly impor\u00adtant. These tech\u00adni\u00adcal spec\u00adi\u00adfi\u00adca\u00adtions ensure the sta\u00adbil\u00adi\u00adty and reli\u00ada\u00adbil\u00adi\u00adty of pow\u00ader grids even under extreme con\u00addi\u00adtions. They set require\u00adments for active and reac\u00adtive pow\u00ader con\u00adtrol, volt\u00adage and fre\u00adquen\u00adcy band\u00adwidths, grid qual\u00adi\u00adty, and behav\u00adior in the event of grid faults.<\/p>\n\n\n\n

A key issue is the dimen\u00adsion\u00ading of the invert\u00aders<\/strong>, espe\u00adcial\u00adly with regard to volt\u00adage ranges, as well as active and reac\u00adtive pow\u00ader capac\u00adi\u00adty at the grid con\u00adnec\u00adtion point. OLTCs in invert\u00ader sta\u00adtion trans\u00adform\u00aders can reduce the need for addi\u00adtion\u00adal reac\u00adtive pow\u00ader com\u00adpen\u00adsa\u00adtion; in pow\u00ader trans\u00adform\u00aders, they are often required by grid codes to reg\u00adu\u00adlate volt\u00adage. Nev\u00ader\u00adthe\u00adless, OLTCs alone are not suf\u00adfi\u00adcient to sat\u00adis\u00adfy all pow\u00ader qual\u00adi\u00adty require\u00adments.<\/p>\n\n\n\n

Dis\u00adtur\u00adbances such as har\u00admon\u00adics, flick\u00ader, res\u00ado\u00adnances, or volt\u00adage fluc\u00adtu\u00ada\u00adtions<\/strong> require project-spe\u00adcif\u00adic solu\u00adtions. MR offers a broad port\u00adfo\u00adlio for this purpose\u2014from sta\u00adt\u00adic sys\u00adtems with capac\u00adi\u00adtors for reac\u00adtive pow\u00ader com\u00adpen\u00adsa\u00adtion and fil\u00adter\u00ading, to dynam\u00adic solu\u00adtions with pow\u00ader elec\u00adtron\u00adics such as active fil\u00adters, SVCs, and STAT\u00adCOMs which enable rapid respons\u00ades to grid dis\u00adtur\u00adbances and thus ensure com\u00adpli\u00adance with grid codes.<\/p>\n<\/div><\/div>\n<\/div><\/div>\n\n\n\n

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ECOTAP\u00ae<\/sup> VPD\u00ae<\/sup> \u2014 the principle<\/h3>\n\n\n\n
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ECOTAP\u00ae<\/sup> VPD\u00ae<\/sup> can be thought of like an auto\u00admat\u00adic trans\u00admis\u00adsion: <\/a>whether going uphill or down\u00adhill, it ensures that the engine always runs in the opti\u00admum speed range. Applied to PV, this means that the invert\u00aders always oper\u00adate at their best, regard\u00adless of how the grid volt\u00adage changes. This means more ener\u00adgy, less down-time, and a longer ser\u00advice life.<\/p>\n\n\n

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Benefits for operators<\/h3>\n\n\n\n
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