Connector device, method for controlling a power flow to a DC load with a connector device

Abstract

A connector device (1) is specified configured to connect an alternating current, AC, power grid (2) to a direct current, DC, load (3), comprising - a multi-winding transformer (4) configured to be connected to the AC power grid (2), - a series voltage injection transformer (8) connected to the multi -winding transformer (4), - an AC / AC converter (13) connected to the series voltage injection transformer (8), and - a rectifier (17) connected to the series voltage injection transformer (8) configured to be connected to the DC load (3). Furthermore, a method for controlling a power flow is specified.

Description

[0001] P2023,1517 WO N / P230094WO01 February20,2025 -1 - Description CONNECTOR DEVICE, METHOD FOR CONTROLLING A POWER FOLW TO A DC LOAD WITH A CONNECTOR DEVICEThe present disclosure relates to a connector devic e and to amethod for controlling a power flow to a DC load wi th aconnectordevice.A typical hydrogen electrolyzer is normally a low v oltageand / orhigh currentDC load thatisfed bya power electronicconverter that performs a transformation of an AC g ridvoltage to a DC voltage. Typical power electronic c onvertertopologies for large-scale green hydrogen productio n arebased on multi-pulse thyristorrectifiercircuits. However,due to harmonic generation and the reactive power c onsumptionof thyristor rectifiers, these rectifiers cause pow er qualityproblems, resulting in requirement of additional ap paratusesand thus resulting in increased system cost and inc reasedfootprint to address the power quality issues and m eet thegrid code requirements for a large-scale electrolyz er plant.Embodiments of the disclosure relate to a connector device. Afurtherembodimentrelatesto a method with such a connector device.This is achieved by the subject-matter of the indep endentclaims. Further embodiments are evident from the de pendentclaimsand the following description.A connector device is described. The connector devi ce isconfigured to connect an alternating current, AC, p ower gridto a direct current, DC, load. The AC power grid is in P2023,1517 WO N / P230094WO01 February20,2025 -2 -particular configured to transmit power from at lea st onepower plant to at least one load. The DC load is, f orexample, configured to be provided with the power o f the ACpower grid. The connector device is particularly co nfiguredto convert AC power of the AC power grid to DC powe r of theDC load.According to an embodiment, the connector device co mprises amulti-winding transformer configured to be connecte d to theAC power grid. The multi-winding transformer is con figuredfor voltage transformation, impedance matching, pha seshifting,and / orelectricalisolation.The multi-winding transformer exemplarily comprises at leasttwo windings. In particular, the at least two windi ngs areconnected to one another. “Connected to one another ” meanshere that the at least two windings are magneticall y coupled.For example, each winding in a multi-winding transf ormer hasa different number of turns, a different wire size, and / or adifferent insulation level. For example, one of the windings,in particular a single winding, of the multi-windin gtransformer, is connected to the AC power grid. Thi s one ofthe windingsisconfigured to receive the AC power ofthe AC powergrid.According to the embodiment, the connector device c omprises aseries voltage injection transformer connected to t he multi-winding transformer. The series voltage injection t ransformerisconnected to one ofthe windings,in particular to asingle winding, of the multi-winding transformer fa cing awayfrom the AC powergrid. P2023,1517 WO N / P230094WO01 February20,2025 -3 -Exemplarily, the series voltage injection transform er isconfigured to receive at least a portion of the AC powerfrom the multi-winding transformer. Exemplarily, th e seriesvoltage injection transformer is configured to inje ct acompensating voltage to parallelconnection lines, which isin particular configured to receive at least one ot herportion of the AC power from the multi-winding tran sformer.Advantageously,using the seriesvoltage injectiontransformer can help to stabilize the voltage profi le, reducevoltage fluctuations, and improve the quality of po werdelivered to the DC load. Also an additional degree -of-freedom is added to the design of a fractional powe rconverter.According to the embodiment, the connector device c omprisesan AC / AC converterconnected to the seriesvoltage injectiontransformer. Exemplarily, the connector device comp risesseveral AC / AC converters, e.g. at least two AC / AC c onverters.The AC / AC converters are in particular connected in parallel.Advantageously, future requirements of DC loads, e. g.hydrogen electrolysers, with a very high current ra ting canbe met.Exemplarily, the AC / AC converter is connected to th e seriesvoltage injection transformer. In particular the AC / ACconverter is connected to the parallel connection l ines,which is in particular configured to receive the at least oneother portion of the AC power from the multi-windin gtransformer. The AC / AC converterexemplarilycomprisesatleast twoconverters, in particular at least two power semico nductor P2023,1517 WO N / P230094WO01 February20,2025 -4 - converters.Exemplarily,one ofthe two converters isa shuntconverter and the other one of the two converters i s a seriesconverter.The two convertersare connected to one another, particularlyin series,exemplarilybya DC link.According to the embodiment, the connector device c omprises arectifier connected to the series voltage injectiontransformer, configured to be connected to the DC l oad. Therectifier is configured to convert the AC power int o a DCpower usable by the DC load. The rectifier is confi gured toprovide a current flow in one direction only, in pa rticularin the direction ofthe DC load.Exemplarily, the rectifier is a diode bridge rectif ier. Thediode bridge rectifier comprises, for example, seve ral diodesarranged in a bridge configuration, e.g. at least s ix diodesarranged in a bridge configuration in particular fo r a three-phase configuration.Advantageously, the connector device disclosed here in offersa unique and versatile solution for feeding and reg ulatingpower to DC loads without affecting the power quali ty of theAC powergrid,while simultaneouslyproviding grid serviceslike reactive power support and active harmonics fi lteringwithout the need for any additional power condition ingdevices.Moreover, the connector device advantageously compr ises theAC / AC converterwith a comparativelylowerrating.Advantageously, in particular, only a fraction of t he powerof rated load power is needed to regulate the power throughthe DC loads, rendering a high-efficiency operation and acompact footprint solution. Furthermore, the presen ce of a P2023,1517 WO N / P230094WO01 February20,2025 -5 -series voltage injection transformer between the AC / ACconverter and the DC load offers an additional degr ee-of-freedom in the design of the AC / AC converter, allow ing thepower semiconductor converters of the AC / AC convert er to beeffectivelyutilized withoutmuch de-rating.According to a further embodiment, the multi-windin gtransformer comprises at least two windings, namely a primarywinding and a secondary winding. Exemplarily, the m ulti-winding transformer comprises exactly two windings, i.e. theprimarywinding and the secondarywinding.According to a further embodiment, the primary wind ing isconfigured to be connected to the AC powergrid.According to a further embodiment, the secondary wi nding isconnected to the series voltage injection transform er. Inparticular, the secondary winding provides the AC p ower ofthe AC power grid from the primary winding to the s eriesvoltage injection transformer.According to a further embodiment, the series volta geinjection transformer comprises at least one transf ormerdevice. The series voltage injection transformer ca n compriseexactly one transformer device, wherein the transfo rmerdevice is in particular a three-phase transformer d evice. Theseries voltage injection transformer can comprise a t leastthree transformer devices, in particular exactly th reetransformerdevices.In particular, when the series voltage injection tr ansformercomprisesatleastthree transformerdevices,eachtransformer device has a primary coil, e.g. an inpu t coil, P2023,1517 WO N / P230094WO01 February20,2025 -6 -and a secondary coil, e.g. an output coil. In parti cular, theprimary coil and the secondary coil are connected t hroughelectromagnetic induction. Exemplarily, the primary coil isdirectly connected to the multi-winding transformer .Exemplarily, the secondary coil is directly connect ed to theswitch element.According to a further embodiment, the series volta geinjection transformer comprises a switch element co nnected tothe at least one transformer device in parallel. Th e switchelementis,forexample,a mechanicalswitch,such asacontactor, or a power electronic switch, exemplaril ycomprising at least one power semiconductor switch, or acombination thereof.According to a further embodiment, the AC / AC conver tercomprisesan AC / DC converterand a DC / AC converter connectedin series. Each AC / DC converter and DC / AC converter compriseat least one semiconductor switching device, for ex ample. Inparticular, the semiconductor switching device is a ninsulated-gate bipolar transistor, IGBT, or a metal -oxide-semiconductorfield-effecttransistor,MOSFET.According to a further embodiment, the DC / AC conver ter isconnected to the series voltage injection transform er on aside ofthe switch element.According to a further embodiment, the AC / DC conver ter isconnected to the DC / AC converterbya DC link.The DC linkcomprises a capacitor, for example. The capacitor i sconfigured, for example, for storing electrical ene rgy. P2023,1517 WO N / P230094WO01 February20,2025 -7 -Advantageously, the capacitor is configured to smoo th outvoltage ripples and fluctuations, ensuring a stable DCvoltage supply.According to a further embodiment, an energy storag e isconnected to the DC link. Exemplarily, the energy s torage isconnected directly to the DC link. Alternatively, t he energystorage is connected to the DC link via a further D C / DCconverter.According to a further embodiment, the AC / DC conver ter isconnected to at least three connection lines betwee n themulti-winding transformer and the series voltage in jectiontransformer. In this embodiment, the AC / DC converte r isconfigured to be the shuntconverterand the DC / AC converter isconfigured to be the seriesconverter.According to a further embodiment, the AC / AC conver ter isconnected to at least three further connection line s betweenthe series voltage injection transformer and the re ctifier.In this embodiment, the AC / DC converter is configur ed to bethe series converter and the DC / AC converter is con figured tobe the shuntconverter.According to a further embodiment, the multi-windin gtransformer comprises at least three windings, name ly theprimary winding, the secondary winding, and a terti arywinding. Exemplarily, the multi-winding transformer comprisesexactly three windings, i.e. the primary winding, t hesecondarywinding and the tertiarywinding.According to a further embodiment, the tertiary win ding isconnected to the AC / AC converter. In this embodimen t, the P2023,1517 WO N / P230094WO01 February20,2025 -8 -secondary winding is directly connected to the seri es voltageinjection transformer, in particular the primary co ils. Inparticular, the tertiary winding is directly connec ted to theAC / AC converter, in particular the AC / DC converter.Exemplarily, the tertiary winding provides the AC p ower ofthe AC power grid from the primary winding to the A C / ACconverter.According to a further embodiment, the tertiary win ding isconnected to a further series voltage injection tra nsformerand to a further AC / AC converter connected to the f urtherseries voltage injection transformer. In particular , thefurther series voltage injection transformer and th e furtherAC / AC converter are each embodied as the series vol tageinjection transformerand the AC / AC convertersuch thatallfeatures in connection with the series voltage inje ctiontransformer and the AC / AC converter are also applic able withthe further series voltage injection transformer an d thefurtherAC / AC converter.According to a further embodiment , a further rectifier isconnected to the furtherseriesvoltage injectiontransformer. In particular, the further rectifier i s embodiedas the rectifier such that all features in connecti on withthe rectifierare also applicable with the further rectifier.According to a further embodiment, the further rect ifier isconfigured to be connected to a further DC load. Inparticular,the furtherDC load isembodied asthe DC loadsuch that all features in connection with the DC lo ad arealso applicable with the further DC load. Exemplari ly, the DCload and the further DC load are electrically and s patiallyseparated from one another. P2023,1517 WO N / P230094WO01 February20,2025 -9 -According to a further embodiment, the rectifier an d thefurtherrectifierare connected to one anotherand areconfigured to be connected to the DC load. Exemplar y, the DCload and the further DC load are electrically conne cted toone another and spatially separated from one anothe r.Exemplarily, the rectifier and the further rectifie r areconnected in parallel or the rectifier and the furt herrectifierin series.According to a further embodiment, the load is a hy drogenelectrolyzer. Exemplarily, for hydrogen electrolyze rapplications,a voltage regulation range UD on the load sideis quite narrow, while the current regulation range ID isvery wide, e.g., a voltage V and current I range at end-of-life,EoL,is483 V ≤ UD ≤ 600 V,3840 A ≤ ID ≤ 9640 A).Advantageously, the connector device is modular, ad aptable toelectrolyzers from different manufacturers and easi lyscalable,making itsapplication fora large-scale hydrogen electrolyzerplantattractive.According to a further embodiment, the load is an e nergystorage. The energy storage is, for example, config ured to becharged via the rectifier.Exemplarily,the energy storage is comprised byan electricvehicle.A further embodiment relates to a method for contro lling apower flow to a DC load with a connector device, pa rticularlythe connector device described herein before. There fore, thefeatures as described in connection with the connec tor deviceare also applicable forthe method and vice versa. P2023,1517 WO N / P230094WO01 February20,2025 -10 -According to an embodiment, controlling a DC voltag e outputof the rectifier is dependent on an AC voltage inpu t to therectifier, such that the power flow to a DC load iscontrolled.According to a further embodiment of the method, an operationprofile ofthe DC load isprovided.According to a further embodiment of the method, th eoperation profile is divided in three operating reg ionsdependenton loading conditionsofthe DC load.According to a further embodiment of the method, fo r two ofthe regions corresponding to a light load condition and aheavyload condition,respectively,the powerflow isregulated by means of a voltage magnitude control o f aninjected voltage of the series voltage injection tr ansformer.According to a further embodiment of the method, fo r one ofthe regions corresponding to a medium load conditio n, thepower flow is regulated by means of an injected vol tagephase-angle control of the series voltage injectiontransformer. A furtherembodimentrelatesto a computerprogram comprisinginstructions which, when the computer program is ex ecuted bya computing device, cause the computer program to e xecute themethod described herein above. In particular, the c omputerprogram can be implemented as hardware control, sof twarecontrol and / or firmware control or combinations the reof. P2023,1517 WO N / P230094WO01 February20,2025 -11 -A further embodiment relates to a computer-readable storagemedium on which the computer program product descri bed hereinabove isstored. The accompanying Figuresare included to provide a furtherunderstanding. In the Figures, elements of the same structureand / orfunctionalitymaybe referenced bythe same reference signs.Itisto be understood thatthe embodiments shown inthe Figures are illustrative representations and ar e notnecessarilydrawn to scale. Figures1,2,3,4 and 5 each schematicallyshow a connector device according to an exemplaryembodiment.Figure 6 schematically shows a connector device con trolled bya method according to an exemplaryembodiment.Figure 7 schematically shows a diagram with differe nt regionsused by a method according to an exemplary embodime nt.The connector device 1 according to the exemplary e mbodimentof Figure 1 comprises a multi-winding transformer 4configured to be connected to an AC power grid 2 an dconnected to a series voltage injection transformer 8 by aconnection line.The multi-winding transformer 4 comprises a primary winding 5facing the AC powergrid 2 and a secondarywinding 6 facingthe connection line. The series voltage injection t ransformer8 comprises three transformer devices 9. Each of th e threetransformer devices 9 comprises a primary coil 10 a nd asecondary coil 11. Each primary coil 10 is connecte d to thesecondary winding 6 by one connection line. Further , the P2023,1517 WO N / P230094WO01 February20,2025 -12 -series voltage injection transformer 8 comprises th ree switchelements 12. Each of the switch elements 12 are con nected toone of the transformer devices 9 in parallel. In pa rticular,each ofthe switch elements12 isconnected to one ofthe secondarycoils11 in parallel.The connector device 1 further comprises an AC / AC c onverter13 connected to the series voltage injection transf ormer 8,in particular in parallel to the series voltage inj ectiontransformer 8, at parallel connection lines 20. The AC / ACconverter13 comprisesan AC / DC converter14 being in particulara shuntconverterand a DC / AC converter 15 beingin particular a series converter. The AC / DC convert er 14 isconnected to the DC / AC converter 15 by a DC link 16 . Inparticular,the DC sidesofthe AC / DC converter14 and theDC / AC converter 15 face one another and are connect ed by theDC link16.The AC / DC converter 14 is connected to the connecti on lines18 between the multi-winding transformer4 and the series voltage injection transformer8.In particular,an AC side ofthe AC / DC converter 14 is connected to the connecti on lines18. The DC / AC converter 15 is connected to the seri es voltageinjection transformer 8, in particular to each of t hesecondary coils 11, on a side facing a rectifier 17 . Inparticular, an AC side of the DC / AC converter 15 is connectedto the seriesvoltage injection transformer8.The connector device 1 further comprises a rectifie r 17connected to the series voltage injection transform er 8,configured to be connected to a DC load 3. In parti cular, theprimary coils 10 are connected to the rectifier 17, inparticularvia furtherconnection lines19. P2023,1517 WO N / P230094WO01 February20,2025 -13 -In particular, the AC / DC converter 14, i.e. the shu ntconverter, is connected to the secondary winding 6. Thisconfiguration advantageously allows the use of stan dard two-windings transformers, resulting in cost savings. R egarding asizing of the shunt converter, since the fundamenta l AC loadcurrent will always be at least approximately in ph ase with avoltage synthesized by series voltage injection tra nsformer8,the injected voltage willalso be in phase with the loadcurrent and the series converter will deliver mostl y activepower. Therefore, the shunt converter can advantage ously besized for at least the same active power as that of theseries converter plus the reactive power required t o meet aunity power factor at the AC power grid 2 side. The shuntconverter also advantageously is configured to canc el out loworder current harmonics, thus performing active har monicsfiltering. This functionality requires an overratin g of theshuntconverter. In contrastto the connectordevice 1 ofFigure 1, theconnector device 1 according to the exemplary embod iment ofFigure 2 comprises a multi-winding transformer 4 w ith aprimary winding 5, a secondary winding 6 and a tert iarywinding 7. The primary winding 5 is configured to b econnected to the AC power grid 2. The secondary win ding 6 isconnected to the connection lines 18 which are conn ected tothe series voltage injection transformer 8. In part icular,each connection line is connected to one of the pri mary coils10, facing the secondary winding 6. The tertiary wi nding 7 isconnected to the AC / DC converter 14 of the AC / AC co nverter13,in particularbythe parallelconnection lines 20. P2023,1517 WO N / P230094WO01 February20,2025 -14 -Exemplarily, the AC / DC converter 14, i.e. the shuntconverter, is connected to the tertiary winding 7 a nd iscontrolled to maintain a constantDC linkvoltage, regulate areactive power exchange with the AC power grid 2, m aintain aunity power factor at a point of common coupling, P CC, andcancel harmonic currents introduced by the rectifie r 17.Thus, by appropriate control, as described in conne ction withFigure 6, the shunt converter is capable of providi ngadvantageous grid services. A provision of an addit ionalwinding on the main transformer,e.g.the tertiary winding 7,offers an additional design variable in optimizatio n of thesizing of the AC / AC converter 13. The series conver ter isconnected via the series voltage injection transfor mer 8 tothe rectifier 17 and the AC power grid 2, thus allo wing theAC voltage fed to the rectifier 17 to be controlled and theDC power flow on the load side to be regulated. The seriesconverter is in particular controlled to regulate t he voltageinjected to the AC line and reduce DC ripples on th e loadside by addition of voltage harmonics, thus flatten ing thetop of the injected AC voltage and reducing DC filt errequirementson the load side.Advantageously, due to the presence of series volta geinjection transformer 8, a turns ratio of the multi -windingtransformer 4 can be leveraged to reduce current st ress onthe series converter and appropriately design the A C / ACconverter 13 with better semiconductor utilization.As a magnitude of the voltage to be injected by the seriesconverter is proportional to a DC voltage regulatio n range ofthe load, which is quite narrow for a hydrogen elec trolyzer,the seriesconverterhasto handle onlya fraction ofthe P2023,1517 WO N / P230094WO01 February20,2025 -15 -rated power of the load. Utilization of this fracti onal poweradvantageously leads to lower losses during power c onversionby the AC / AC converter 13 and overall to lower powe r lossesand a compactfootprint.Exemplarily, the energy storage, e.g. a battery ene rgystorage, BESS, is directly connected to the DC-link . Thisadvantageously allows a rapid frequency control fun ctionalityto be delivered to the AC power grid 2 and supports the load,in particular the hydrogen electrolyzer, during a s tart-upand during faultconditionsatthe AC powergrid 2 side.Exemplarily, a grid forming control, e.g. a VirtualSynchronous Machine Control, of the AC / DC converter can beincluded in thiscase to supportthe AC powergrid voltage and frequency.In contrast to Figure 1, the shunt converter and th e seriesconverterare interchanged in the connectordevice 1 according to the exemplaryembodimentofFigure 3. The seriesvoltage injection transformer 8 comprises three swi tchelements 12, which are not shown in Figure 3 for be tterrepresentability,asshown in Figures1 and 2.The AC / DC converter 14 is connected to the series v oltageinjection transformer 8, in particular to the secon dary coils11. Particularly the AC side of the AC / DC converter 14 isconnected to the series voltage injection transform er 8.The DC / AC converter15 isconnected to the further connectionlines 19, with which the series voltage injection t ransformer8 isin particularconnected to the rectifier17. P2023,1517 WO N / P230094WO01 February20,2025 -16 -In particular, the order of the series and shunt co nverter isreplaced in contrast to Figure 1 so that current ha rmonicsgenerated bythe rectifier17 are mitigated atthe source ofharmonics generation by an active harmonics filteri ngcapability of the shunt converter and the harmonics currentdoesnotflow through the seriesvoltage injection transformer8. In contrastto the connectordevice 1 ofFigure 1, theconnector device 1 according to the exemplary embod iment ofFigure 4 comprises a multi-winding transformer 4 w ith aprimary winding 5, a secondary winding 6 and a tert iarywinding 7. The tertiary winding 7 is connected to a furtherseries voltage injection transformer 21 and a furth er AC / ACconverter 13, which are connected to the tertiary w inding 7in the same way as the series voltage injection tra nsformer 8and the AC / AC converter 13 are connected to the sec ondarywinding 6 described in Figure 1. Furthermore, the f urtherseries voltage injection transformer 21 is connecte d to afurtherrectifier23.The rectifier 17 and the further rectifier 23 are c onnectedto one another. Further, the rectifier 17 and the f urtherrectifier 23 are connected to the load. In particul ar, therectifier 17 and the further rectifier 23 are conne cted inseries on the DC load 3 side. This configuration ca nadvantageouslyresultin reduced DC rippleson the DC load 3 side and willalso be suitable fornext-generation high voltage hydrogen electrolyzersin the future.In contrast to Figure 4, the connector device 1 acc ording tothe exemplary embodiment of Figure 5 comprises a fu rtherload. The rectifier 17 and the further rectifier 23 are not P2023,1517 WO N / P230094WO01 February20,2025 -17 - connected to one another.The furtherrectifier23 is connected to the furtherDC load 24.This means that the connector device 1 according to theexemplary embodiment of Figure 5 is based on 12-pul seconfiguration. This configuration comprises the add ing of anadditionalmodule with the furtherAC / AC converter and thefurther rectifier 23 to the tertiary winding 7 of a multi-windings transformer. This configuration can advant ageouslyhelp to reduce AC harmonics filtering requirements,simplifying control, and lowering the ratings of th e shuntconverter. Forcontrolling a powerflow to the DC load 3 with a connectordevice 1,exemplarilya connectordevice 1according to Figure 1, a DC voltage output of the r ectifier17 is controlled dependent on an AC voltage input t o therectifier 17, such that the power flow to the DC lo ad 3 iscontrolled.Therefore, a controller 25 is connected to the conn ectordevice 1. The controller 25 is, for example, config ured toregulate a DC load 3 voltage V DCand a power flowing to theDC load 3 by controlling a magnitude of the voltage V Seriesinjected by the series voltage injection transforme r 8.The shuntconverteriscontrolled to maintain a DC link16voltage V DC-Ling constant, mitigate current harmonics generatedby the rectifier 17 and maintain a unity power fact or.Furthermore, the controller 25 is, for example, con figuredfor frequency regulation and power oscillation damp ing on theAC power grid 2 side by controlling a DC side activ e power asa function of the AC side frequency f Grid . P2023,1517 WO N / P230094WO01 February20,2025 -18 -Exemplarily, the shunt converter and the series con verter canboth be individually controlled by the controller 2 5 viapulse width modulation, as indicated with black arr owspointing to the respective converter.Exemplarily, for a symmetrical voltage injection me thod, tocontrol the power flow to the DC load 3, the series converteris configured to inject a symmetrical bipolar volta ge ( ΔU = ±xV) to an AC voltage (U 1)on a side facing the secondarywinding 6 so that a magnitude of a cumulative AC vo ltage fedto the rectifier 17 (U AC) can be increased (U AC= U 1 + xV) ordecreased (U AC= U 1 - xV) with respect to the AC voltage (U 1)on the side facing the secondarywinding 6. With the connectordevice 1 and / orthe method,the DC voltageis advantageously regulated at the DC load 3 side w hilesimultaneously performing active harmonics filterin g andreactive power support at the AC power grid 2 side, inparticular without requiring any additional power q ualityimprovement apparatus. Advantageously, the series v oltageinjection transformer 8 is configured to inject the voltageon the AC side of the rectifier 17. The series volt ageinjection transformer 8 advantageously offers an ad ditionaldegree-of-freedom in the design of the AC / AC conver ter 13 andhelps to optimally utilize the power semiconductors withoutrequiring much derating ofthe AC / AC converter.In particular, the connector device 1 is advantageo uslymodular and easily scalable, making it an attractiv e optionfor large-scale hydrogen electrolyzers. As the conn ectordevice 1 advantageously needs only partial rating p ower P2023,1517 WO N / P230094WO01 February20,2025 -19 -converters, it is cheaper compared to the conventio nalsolutions that require full rating power converters .Advantageously, with appropriate control, the volta ge rippleson the load side and currentharmonicson the grid side arereduced. This can lower filtering requirements both on theload and the grid side.In connection with the diagram in Figure 7, with th e methoddescribed in connection with Figure 6 the operation of the DCload 3 can be divided into three-distinct operating regions,namelyregion A,B and C asindicated in Figure 7, based onloading conditions, e.g. an operation profile of th e DC load3. On the y-axis,a voltage ofthe load isindicated, and on thex-axis, a current of the load is indicated, corresp onding tothe operation profile of the DC load 3, in particul ar for twodifferentprofiles. ForregionsA and C,corresponding to a lightload condition and a heavyload condition respectively,the power flow is regulated bymeansofvoltage magnitude controlof theinjected voltage of the series converter, e.g. an a nti-phaseoperation, and an in-phase operation, respectively. Forregion B, corresponding to a medium load condition, the powerflow is regulated by means of injected voltage phas e-anglecontrol of the series converter, e.g. an out-of-pha seoperation.Forregion B,the seriesconverteralso exchanges reactive powerwith the AC powergrid 2. The anti-phase operation isdescribed exemplarily. Forregion A,the voltage injected bythe seriesconverteris in anti- P2023,1517 WO N / P230094WO01 February20,2025 -20 - phase relationship,i.e.,180°phase-shifted,e.g. out-of- phase,with respectto the AC-side voltage and the powerflowto the DC load 3 is controlled by varying the volta gemagnitude only. There is no reactive power exchange betweenthe series converter and the DC load 3 and / or the A C powergrid 2 in thisregion ofoperation.The out-of-phase-operation is described exemplarily . Forregion B,a phase-angle ofthe voltage injected by the seriesconverter is varied while the magnitude of the inje ctedvoltage iskeptconstantata pre-specified levelcorresponding to a minimum value of realizable modu lationindex. This is done to prevent the operation of the seriesconverter at a very low modulation index and in the vicinityofthe zero-voltage range ofthe seriesconverter, which ispractically unachievable. As the phase-angle of the injectedvoltage is varied in this mode of operation while k eeping thevoltage magnitude constant, the series converter al soexchanges active and reactive power with the AC pow er grid inthismode ofoperation.The in-phase operation is described exemplarily. Fo r regionC,the voltage injected bythe seriesconverteris in phasewith respect to the AC-side voltage and the power f low to theDC load 3 is controlled by varying the voltage magn itudeonly. There is no reactive power exchange between t he seriesconverterand the DC load 3 and / orAC powergrid 2 in this region ofoperation. Exemplarily,foran asymmetricalvoltage injection method, the seriesconverterisconfigured to be in either an in-phase relationship or an anti-phase relationship fo r all ofthe loading conditions of the rectifier 17. For the case P2023,1517 WO N / P230094WO01 February20,2025 -21 -where the series converter is operated in the in-ph aserelationship only, the voltage U 1 is selected to be lowerthan a minimum AC voltage requirement U AC,min of the rectifier17 so that the series converter can effectively ste p up U 1 byΔU where ΔU variesfrom +xV to +yV asshown in Figure 8.For the case where the series converter is only ope rated inthe anti-phase relationship, the voltage U 1 is selected to behigher than a maximum AC voltage requirement U AC,max of therectifier 17 so that the series converter can effec tivelystep down U 1 by ΔU where ΔU varies from -xV to -yV as shownin Figure 9.As the ratings of the series converter and the seri es voltageinjection transformer 8 are proportional to the mag nitude ofthe injected voltage, this control method results i n higherpower ratings of the series converter as compared t o thesymmetricalvoltage injection method.The embodiments and exemplary embodiments described hereinabove can be combined accordingly.

[0002] P2023,1517 WO N / P230094WO01 February20,2025 -22 - Reference Signs 1 connectordevice 2 powergrid 3 DC load 4 multi-winding transformer 5 primarywinding 6 secondarywinding 7 tertiarywinding 8 seriesvoltage injection transformer 9 transformerdevice 10 primarycoil 11 secondarycoil 12 switch element 13 AC / AC converter 14 AC / DC converter 15 DC / AC converter 16 DC link 17 rectifier 18 connection lines 19 furtherconnection lines 20 parallelconnection lines 21 furtherseriesvoltage injection transformer 22 furtherAC / AC converter 23 furtherrectifier 24 furtherDC load 25 controller

Claims

P2023,1517 WO N / P230094WO01 February20,2025 -23 - Claims1. Connector device (1) configured to connect an al ternatingcurrent, AC, power grid (2) to a direct current, DC , load(3),comprising -a multi-winding transformer(4)configured to be connected to the AC powergrid (2),- a series voltage injection transformer (8) connec ted to themulti-winding transformer(4),- an AC / AC converter (13) connected to the series v oltageinjection transformer(8),and -a rectifier(17)connected to the seriesvoltage injectiontransformer (8) configured to be connected to the D C load(3).

2. Connector device (1) according to claim 1, where in- the multi-winding transformer (4) comprises at le ast twowindings, namely a primary winding (5) and a second arywinding (6),- the primary winding (5) is configured to be conne cted tothe AC powergrid (2),and- the secondary winding (6) is connected to the ser iesvoltage injection transformer(8).

3. Connector device (1) according to one of the cla ims 1 or2,wherein- the series voltage injection transformer (8) comp rises atleastone transformerdevice (9),and- the series voltage injection transformer (8) comp rises aswitch element (12) connected to the at least one t ransformerdevice (9)in parallel.P2023,1517 WO N / P230094WO01 February20,2025 -24 - 4.Connectordevice (1)according to one ofclaims 1 to 3, wherein- the AC / AC converter (13) comprises an AC / DC conve rter (14)and a DC / AC converter(15)connected in series.

5. Connector device (1) according to claims 3 and 4 , wherein- the DC / AC converter (15) is connected to the seri es voltageinjection transformer (8) on a side of the switch e lement(12). 6.Connectordevice (1)according to one ofclaims 4 or5, wherein- the AC / DC converter (14) is connected to the DC / A Cconverter(15)bya DC link(16).

7. Connector device (1) according to claim 6, where in- an energy storage is connected to the DC link (16 ).8.Connectordevice (1)according to one ofclaims 5 to 7, wherein- the AC / DC converter (14) is connected to at least threeconnection lines (18) between the multi-winding tra nsformer(4) and the series voltage injection transformer (8 ), or- the AC / AC converter (13) is connected to at least threefurther connection lines (19) between the series vo ltageinjection transformer(8)and the rectifier(17). 9.Connectordevice (1)according to one ofclaims 2 to 7, wherein- the multi-winding transformer (4) comprises at le ast threewindings, namely the primary winding (5), the secon darywinding (6),and a tertiarywinding (7),andP2023,1517 WO N / P230094WO01 February20,2025 -25 -- the tertiary winding (7) is connected to the AC / A Cconverter(13).

10. Connector device (1) according to one of claims 2 to 7,wherein- the multi-winding transformer (4) comprises at le ast threewindings, namely the primary winding (5), the secon darywinding (6)and a tertiarywinding (7),and- the tertiary winding (7) is connected to a furthe r seriesvoltage injection transformer(8)and to a further AC / ACconverter (22) connected to the further series volt ageinjection transformer(21),and- a further rectifier (23) is connected to the furt her seriesvoltage injection transformer(21).

11. Connector device (1) according to claim 10, whe rein- the further rectifier (23) is configured to be co nnected toa furtherDC load (24). 12.Connectoraccording to claim 10,wherein- the rectifier (17) and the further rectifier (23) areconnected to one another and are configured to be c onnectedto the DC load (3).

13. Connector device (1) according to one of claims 1 to 12,wherein -the load isa hydrogen electrolyzer,or -the load isan energystorage.

14. Method for controlling a power flow to a DC loa d (3) witha connector device (1) according to one of claims 1 to 13,comprising:P2023,1517 WO N / P230094WO01 February20,2025 -26 - -controlling a DC voltage outputofthe rectifier (17)dependent on an AC voltage input to the rectifier ( 17), suchthat -the powerflow to the DC load (3)iscontrolled. 15.Method according to claim 14,comprising:- providing an operation profile of the DC load (3) ,- dividing the operation profile in three operating regionsdependent on loading conditions of the DC load (3),- for two of the regions corresponding to a light l oadcondition and a heavy load condition, respectively, the powerflow is regulated by means of a voltage magnitude c ontrol ofan injected voltage of the series voltage injectiontransformer(8),and -forone ofthe regionscorresponding to a medium load condition,the powerflow isregulated bymeansof an injected voltage phase-angle controlofthe series voltage injection transformer(8).

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