Energy storage system, method for electrically isolating at least one storage module system and method for transferring energy

Abstract

An energy storage system (1) is specified, comprising - an energy storage string (2) with energy storage modules (3) connected in series through current breaking elements (6), and - a parallel line with switches (9) being connected in series, wherein - each energy storage module (3) is connected to on e of the current breaking elements (6), - each switch (9) is connected in parallel with a respective energy storage module (3) and a respective current breaking element (6), - the respective switch (9) is configured to provid e a current path through the respective energy storage module (3) and the respective current breaking element (6), an d - the respective switch (9) is configured to discon nect the respective energy storage module (3) from the energy storage string (2). Additionally, a method for electrically isolating at least one energy storage module in an energy storage system and a method for transferring energy from at least one en ergy storage module to at least one other energy storage module in an energy storage system is specified.

Description

[0001] P2024,0048 WO E / P230173WO01 March 28,2024 -1 - Description ENERGY STORAGE SYSTEM,METHOD FOR ELECTRICALLY ISOALTING AT LEAST ONE STORAGE MODULE SYSTEM AND METHOD FOR TRSAFNERRING ENERGYThe present disclosure relates to an energy storage system, amethod for electrically isolating at least one ener gy storagemodule in an energy storage system and a method fortransferring energy from at least one energy storag e moduleto at least one other energy storage module in an e nergystorage system.Typically, energy storage systems play a crucial ro le inensuring stability and reliability of electrical po wer gridswith renewable energysystems.Embodiments of the disclosure relate to an energy s toragesystem which has an improved functionality. Furtherembodiments relate to methods for operation of such an energystorage system.This is achieved by the subject-matter of the indep endentclaims. Further embodiments are evident from the de pendentclaimsand the following description.An energy storage system is described. Exemplarily, theenergy storage system is connected to an electrical powergrid. In particular, the energy storage system is c onfiguredto reduce energy imbalances of the electrical power grid. Inparticular, the energy storage system is configured toreceive an electrical current from the electrical p ower grid P2024,0048 WO E / P230173WO01 March 28,2024 -2 - aswellasto provide an electricalcurrentto the electrical powergrid.According to an embodiment, the energy storage syst emcomprises an energy storage string with energy stor agemodules connected in series through current breakin gelements. Exemplarily, the energy storage string is connectedto a power transmission system connected to the ele ctricalpower grid and connected to an energy source and / or an energyload. For example, the energy storage string is arr angedbetween the power transmission system and an electr icalreference potential, which is, in particular, a gro undpotential,i.e.,a ground.The energy storage modules are each configured to r eceive anelectrical current from the power transmission syst em as wellas to provide an electrical current to the power tr ansmissionsystem, in particular independently from one anothe r.Exemplarily, each of the energy storage modules com prises anenergystorage block.The energystorage blockis, for example,an electricalenergyaccumulatorwhich is configuredto store and release electric energy. The energy st orageblock is, for example, at least one of a battery mo dule and asupercapacitor. The energy storage block comprises, forexample, at least two terminals, a first terminal a nd asecond terminal. In particular, the terminals diffe r from oneanother in their polarity. If the energy storage is abattery, the terminals comprise an anode terminal a nd acathode terminal. If the energy storage is a superc apacitor,the terminals comprise a positive terminal and a ne gativeterminal. P2024,0048 WO E / P230173WO01 March 28,2024 -3 -The energy storage block can further comprise elect ricalstorage cells being connected to one another. For e xample,the electrical storage cells are connected in serie s and / orin parallelto one another.For example, directly neighbouring energy storage m odules areconnected to one another with a connection, wherein theconnection is formed exemplarily by a wire, a busba r and / or aconnector. In particular, each connection electrica llyconnects the first terminal and the second terminal ofdirectly neighbouring energy storage modules with o neanother. The current breaking elements are exemplar ilyarranged between directly neighbouring energy stora ge modulesatthe respective connection.For example, each current breaking element is confi gured todisconnect directly neighbouring energy storage mod ules fromone another. In particular, the current breaking el ement isconfigured to transmit electrical current between d irectlyneighbouring energy storage modules when the curren t breakingelementisin the closed state.In particular,the currentbreaking element is configured to interrupt electri calcurrent between directly neighbouring energy storag e moduleswhen the current breaking element is in an open sta te.Exemplarily, the state of the current breaking elem ent isdependent on an electrical current which is applied to thecurrentbreaking element.According to the embodiment, the energy storage sys temcomprises a parallel line with switches being conne cted inseries. Exemplarily, a number of energy storage mod ulesequals a number of switches, such that one of the s witchesand one of the current breaking elements are connec ted to one P2024,0048 WO E / P230173WO01 March 28,2024 -4 - respective energystorage module.Alternatively,a numberofenergy storage modules is larger than a number of s witches,such that at least two of the switches and / or at le ast two ofthe currentbreaking elementsare connected to one respective energystorage module.For example, directly neighbouring switches are con nected toone another with an interconnection. Exemplarily, e achinterconnection is electrically connected to a resp ectiveconnection connecting directlyneighbouring energy storagemodules. The switches are exemplarily formed of a m echanicalswitch and / or an electrical switch or a combination thereof.Exemplarily, the switch is operated with an externa l controldevice.In particular, the switch is configured to transmitelectrical current when the switch is in the closed state. Inparticular, the switch is configured to interrupt e lectricalcurrentwhen the switch isin an open state.According to the embodiment of the energy storage s ystem,each energy storage module is connected to one of t he currentbreaking elements. Exemplarily, at least one energy storagemodule is connected to exactly one of the current b reakingelementsand / orto exactlyone ofthe switches.Inparticular, exactly one current breaking element an d / orexactly one switch is assigned to at exactly one en ergystorage module. Exemplarily, the connection connect ingdirectly neighbouring energy storage modules compri sesexactlyone currentbreaking element.For example, at least two energy storage modules ar econnected to exactly one of the current breaking el ements P2024,0048 WO E / P230173WO01 March 28,2024 -5 -and / or to exactly one of the switches. In particula r, exactlyone current breaking element and / or exactly one swi tch isassigned to at more than one neighboring energy sto ragemodulesconnected in series.According to the embodiment of the energy storage s ystem,each switch is connected in parallel with a respect ive energystorage module and a respective current breaking el ement.Exemplarily, exactly one switch is connected in par allel withexactly one respective energy storage module connec ted toexactlyone currentbreaking element.According to the embodiment of the energy storage s ystem, therespective switch is configured to provide a curren t paththrough the respective energy storage module and th erespective current breaking element. Exemplarily, t he currentbreaking element is controlled dependent on a state of theswitch. The switch is, for example, configured to g enerate anartificial short circuit current when in the closed state. Inparticular, if the switch is in the closed state, t he energystorage module is shortened by the respective energ y storagemodule and the respective interconnection in partic ular bythe artificialshortcircuitcurrent.Exemplarily, the state of the current breaking elem ent isdependent on an electrical current, which is applie d to thecurrent breaking element. Exemplarily, if an accumu latedvalue of the artificial short circuit current is hi gher thana threshold value,the respective currentbreaking elementis configured to be in the opened state,particularly disconnecting directlyneighbouring energystorage modulesfrom one another. Exemplarily, the accumulated valu e can bepreset to be higher than the threshold value by clo sing the P2024,0048 WO E / P230173WO01 March 28,2024 -6 -switch. The threshold value is, for example, charac teristicof a breaking current limit of the current breaking element.If the accumulated value of the artificial short ci rcuitcurrent is smaller than the threshold value, the re spectivecurrent breaking element is configured to be in the closedstate, particularly connecting directly neighbourin g energystorage modules to one another. Exemplarily, the ac cumulatedvalue can be preset to be smaller than the threshol d valuedepending on closing and opening the switch with a preset frequency.According to the embodiment of the energy storage s ystem, therespective switch isconfigured to allow a current flow through the respective currentbreaking elementto disconnectand bypass the respective energy storage module fro m theenergystorage string.In particular,ifdirectlyneighbouring energy storage modules are disconnecte d by therespective currentbreaking element,the switch is configured to be in the closed state,in particularto bypass the respective energystorage module. Advantageously,with such an energystorage system a faultyenergy storage module can be isolated and bypassed, therebyallowing continuousoperation ofthe otherhealthy energystorage modules. A balancing of energy can advantag eously beimplemented among neighbouring energy storage modul es,leading to an optimal use of the available energy s toragemodules’ capacity. This avoids unnecessary oversizi ng of theenergystorage system.Particularly, with such an energy storage system, a lifetimeof the energy storage modules can be maximised, and an P2024,0048 WO E / P230173WO01 March 28,2024 -7 -accelerated aging of the energy storage modules can beminimized by the energy balancing. In particular, t his leadsto reduced energy losses and lower operating expens es due tothe active energyredistribution.According to a further embodiment of the energy sto ragesystem, each switch is connected to one of the curr entbreaking elements by an impedance line. The impedan ce lineis,forexample,comprised bythe interconnection.Exemplarily, the interconnection and / or the impedan ce line isformed bya wire,a busbarand / ora connector.Exemplarily, at least some of the impedance lines a re eachsolely characteristic of an impedance of the connec tion andthe interconnection.Alternatively or additionally, at least some of the impedancelines comprise an inductor. Exemplarily, at least s ome of theimpedance lines are each characteristic of the impe dance ofthe connection, the interconnection, and the induct or.According to a further embodiment of the energy sto ragesystem, at least one current breaking element is co nfiguredto electrically isolate the respective energy stora ge moduledependent on a first operational mode of the respec tiveswitch.Exemplarily,the firstoperationalmode is characteristicofclosing the switch such thattheaccumulated value of the artificial short circuit c urrent ishigherthan the threshold value and the respective current breaking elementisopened.According to a further embodiment of the energy sto ragesystem, the impedance lines are configured to trans fer energy P2024,0048 WO E / P230173WO01 March 28,2024 -8 -from the respective energy storage module to direct lyneighboring energy storage modules dependent on a s econdoperational mode of the respective switch. Exemplar ily, thesecond operational mode is characteristic of closin g andopening the switch with a preset frequency such tha t theaccumulated value is smaller than the threshold val ue. Forexample, the second operational mode is characteris tic of apulse width modulation of a driving signal of the s witch,particularly characteristic of the closing and open ing of theswitch.According to a further embodiment of the energy sto ragesystem, each current breaking element is arranged o n aconnection between the respective energy storage mo dule andthe respective switch.According to a further embodiment of the energy sto ragesystem, the switch is a power semiconductor switch. The powersemiconductor switch comprises, for example, a Meta l-Oxide-Semiconductor Field-Effect Transistor, MOSFET, and / or anInsulated Gate BipolarTransistor,IGBT.Advantageously, by using power semiconductor switch es, thecomparatively rapid switching of the second operati onal mode,in particularwith minimallosses,isachieved.According to a further embodiment of the energy sto ragesystem, at least some of the current breaking eleme ntscomprise a fuse. Exemplarily, the fuse is configure d to open,e.g.being operated in the opened state,dependent on anovercurrent event. The overcurrent event is in part icularcharacteristic of the accumulated value of the arti ficialshort circuit current being higher than the thresho ld value. P2024,0048 WO E / P230173WO01 March 28,2024 -9 -In particular, the fuse automatically opens depende nt on theovercurrent event. “Automatically” means here and i n thefollowing that the current breaking element is conf igured toopen dependent on the current flowing through the c urrentbreaking element.If the current breaking element is formed as a fuse ,advantageously, solely the switch has to be operate dactively, e.g. by the external control device. Thisadvantageously is comparatively communication resou rce-saving.According to a further embodiment of the energy sto ragesystem, at least some of the current breaking eleme ntscomprise an isolation switch. The isolation switch, forexample, is configured to open, e.g. being operated in theopened state,dependenton the overcurrenteventautomatically or manually. “Manually” means here an d in thefollowing that the current breaking element is conf igured toopen dependenton a controlsignalprovided to the current breaking elementfrom an externalcontroldevice.According to a further embodiment of the energy sto ragesystem, at least some of the impedance lines compri se aninductor. Exemplarily, all impedance lines comprise aninductor.According to a further embodiment, the energy stora ge systemfurther comprises a further parallel line with furt herswitchesbeing connected in series.In particular, thefurther parallel line is connected in parallel to t heparallelline. P2024,0048 WO E / P230173WO01 March 28,2024 -10 -According to a further embodiment of the energy sto ragesystem, each further switch is connected in paralle l with arespective energy storage module and a respective c urrentbreaking element. For example, directly neighbourin g furtherswitches are connected to one another with a furthe rinterconnection. Exemplarily, each further intercon nection iselectricallyconnected bya furtherimpedance line to arespective connection connecting directly neighbour ing energystorage modules.According to a further embodiment of the energy sto ragesystem,each furtherswitch isconnected to one of thecurrent breaking elements by a further impedance li ne.According to a further embodiment of the energy sto ragesystem, at least some of the further impedance line s comprisea furtherinductor.According to a further embodiment of the energy sto ragesystem, every second impedance line comprises the i nductor,every second further impedance line comprises the f urtherinductor, and the impedance line comprises the indu ctor ifthe further impedance line comprises no further ind uctor.According to a further embodiment of the energy sto ragesystem, a resistor is arranged between two connecti ons of oneenergy storage module. Exemplarily, at least some a nd or allconnections are connected to the resistor. In parti cular,each resistor is arranged between two connections c onnectedto the firstterminaland the second terminalofa respective single energystorage module. P2024,0048 WO E / P230173WO01 March 28,2024 -11 -According to a further embodiment of the energy sto ragesystem, a resistor module is connected to the switc h. Inparticular, a resistor module is connected to at le ast someofthe switchesorallofthe switches.According to a further embodiment of the energy sto ragesystem, the resistor module comprises a resistor an d a bypassswitch.According to a further embodiment of the energy sto ragesystem,the resistormodule isconnected in series to theswitch, and the bypass switch is arranged in parall el to theresistor. In particular, the bypass switch is confi gured inthis embodiment to bypass the resistor when the byp ass switchisin an opened state.According to a further embodiment of the energy sto ragesystem, the resistor module is connected in paralle l to theswitch, and the bypass switch is arranged in series to theresistor. In particular, the bypass switch is confi gured inthis embodiment to bypass the resistor when the byp ass switchisin a closed state.Advantageously, the resistors are used to discharge therespective energy storage module to a voltage level which issafe to handle.According to a further embodiment, the energy stora ge systemfurther comprises a further energy storage string c onnectedin parallel to the energy storage string. The furth er energystorage string is embodied as the energy storage st ringdescribed herein before. Additionally, the energy s torage P2024,0048 WO E / P230173WO01 March 28,2024 -12 -system can comprise a plurality of further energy s toragestringsconnected in parallelto one another. Advantageously,the switchesofthe energystorage string andthe further energy storage string are used to suppr esscirculating currents among parallelly connected ene rgystorage strings by ensuring a voltage balancing amo ng theparallelenergystorage strings.A further embodiment relates to a method for electr icallyisolating atleastone energystorage module in an energystorage system, in particular an energy storage sys temdescribed herein above.Therefore,the featuresas describedin connection with the method are also applicable f or theenergystorage system and vice versa.According to an embodiment of the method, the switc hconnected to the at least one energy storage module isclosed, such that an artificial short current is ge nerated.According to an embodiment of the method, the curre ntbreaking element connected to the at least one ener gy storagemodule is triggered dependent on the artificial sho rtcurrent,such thatthe atleastone energystorage module iselectrically isolated from the other energy storage modules.According to a further embodiment of the method, th e switchis closed dependent on a monitoring information. Th emonitoring information comprises, for example, a st ateinformation of the respective energy storage module . Thestate information comprises, for example, a state o f charge,a state of health and / or a temperature. If the moni toringinformation is indicative of an energy storage modu le which P2024,0048 WO E / P230173WO01 March 28,2024 -13 -does not function normally, the switch is closed in ducing theartificialshortcurrent.Exemplarily, the external control device is configu red tomonitor the monitoring information and is further c onfiguredto operate the respective switch dependent on the m onitoringinformation.A further embodiment relates to a method for transf erringenergy from at least one energy storage module to a t leastone other energy storage module in an energy storag e system,in particular an energy storage system described he reinabove. Therefore, the features as described in conn ectionwith the method are also applicable forthe energy storage system and vice versa.According to an embodiment of the method, the switc hconnected to the at least one energy storage module is closedfor a time interval, such that electric energy of t he atleast one energy storage module is stored in the re spectiveimpedance line.According to an embodiment of the method, the switc h of theatleastone energystorage module isopened,such that electricenergyofthe atleastone energystorage module is released from the respective impedance line to the atleastone other energy storage module. Exemplarily, the s witch ofthe at least one energy storage module is opened fo r afurthertime intervalsuch thatelectricenergyof the atleast one energy storage module is released from th erespective impedance line to the at least one other energystorage module. P2024,0048 WO E / P230173WO01 March 28,2024 -14 -Exemplarily, the switch connected to the at least o ne energystorage module is closed and opened with the presetfrequency. This means that the time interval and th e furthertime interval are subsequent to one another and alt ernatewith one another.According to a further embodiment of the method, th e timeinterval is determined such that an accumulated val ue of theartificial short current is smaller than a threshol d value.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.Figure 1 schematically shows an energy storage syst emaccording to an exemplaryembodiment.Figure 2 schematically shows a part of an energy st oragesystem according to an exemplaryembodiment.Figures 3 and 4 schematically show a method for ope rating anenergy storage system according to an exemplary emb odiment.Figure 5 schematically shows an energy storage syst emaccording to an exemplaryembodiment.Figures 6, 7, 8 and 9 schematically show a method f oroperating an energystorage system according to an exemplary embodiment. P2024,0048 WO E / P230173WO01 March 28,2024 -15 -Figures 10, 11, 12, 13 and 14 each schematically sh ow anenergy storage system according to an exemplary emb odiment.The energy storage system 1 according to the exempl aryembodimentofFigure 1 comprisesan energystorage string 2with energy storage modules 3 connected in series t hroughcurrent breaking elements 6. For example, the energ y storagestring 2 is arranged between a power transmission s ystem anda reference potential.On a side facing the powertransmission system, an energy storage system isola tor switch14 is arranged for electrically isolating the energ y storagestring 2 as a whole. A string current 13 is indicat ed,wherein the arrow in Figure 1 ischaracteristicof thecurrent flowing from the energy storage string 2 to the powertransmission system.Each energy storage module 3 is connected to one of thecurrent breaking elements 6. Each energy storage mo dule 3comprises a first terminal 4 indicated with a “-” p olarity inFigure 1 and a second terminal 5 indicated with a “ +”polarityin Figure 1.Directlyneighbouring energy storagemodules 3 are connected to one another with a conne ction 7,wherein each connection 7 electrically connects a f irstterminal 4 and a second terminal 5 of directly neig hbouringenergy storage modules 3. Each connection 7 compris es one ofthe current breaking elements 6. Each of the curren t breakingelements6 isparticularlyformed asa fuse.The energy storage system 1 further comprises a par allel linewith switches 9 being connected in series. Each swi tch 9 isconnected in parallel with a respective energy stor age module3 and a respective current breaking element 6. Dire ctlyneighbouring switches 9 are connected to one anothe r with an P2024,0048 WO E / P230173WO01 March 28,2024 -16 -interconnection 10. Each interconnection 10 is elec tricallyconnected to a respective connection 7 connecting d irectlyneighbouring energy storage modules 3 by an impedan ce line11. Particularly, the impedance line 11 further com prises aninductor 12. The inductor 12 is, for example, reali zed by adiscrete inductor or by a magnetic core arranged ar ound theimpedance line 11. Advantageously, such an inductor 12 is asaturable inductor, offering a negligible impedance atcomparativelyhigh currents.A respective switch 9 is configured to provide a cu rrent paththrough the respective energystorage module 3 and therespective current breaking element 6, and the resp ectiveswitch 9 is configured to disconnect the respective energystorage module 3 from the energystorage string 2, asdescried in more detail in connection with Figure 2 and / orFigures3 and 4.Advantageously, a combination of the current breaki ng element6 formed as a fuse and a switch 9 is used for elect ricalisolation and bypassing a faulty energy storage mod ule 3.Particularly, the fuse is triggered by a state of t he switch9.Additionally,such an energystorage system 1advantageously ensures a voltage balancing by redis tributingenergy among at least some of the energy storage mo dules 3connected in series.The current breaking element 6 formed as a fuse acc ording tothe exemplaryembodimentofFigure 2 isconfigured to beoperated to be in the opened state, e.g. operated t o melt,dependent on a state of the switch 9. When the swit ch 9 is inthe closed state, the energy storage module 3 is sh ortenedthrough the fuse and the impedance lines 11 of a cl osed path. P2024,0048 WO E / P230173WO01 March 28,2024 -17 -This means that an artificial short circuit current isgenerated when the switch 9 is in the closed state. Animpedance of the closed path is in particular a com binationof an internal impedance of the energy storage modu le 3 andan externalimpedance,e.g.from the connection 7, theinterconnection 10 and the impedance line 11 partic ularlycomprising the inductor12.When the current breaking element 6 is in the opene d state,the switch 9 remainsin the closed state to bypass arespective faulty energy storage module 3. Advantag eously, acontinued operation ofthe energystorage string 2 isthus achieved – with reduced capacity.The artificial short circuit current is exemplarily solelydependent on a voltage of the energy storage module 3 and theimpedance ofthe closed path.Advantageously,such an artificialshortcircuitcurrentvariesonlyin acomparatively small range. Therefore, a tight contr ol over aclearing time is advantageously achieved. Typically , fornormal fuses it takes a long time to clear a faulty energystorage module 3 when a fault current is low. Howev er, withsuch an energy storage system 1, once the faulty en ergystorage module 3 is detected, the faulty energy sto ragemodule 3 can be cleared comparatively fast by gener ating theartificialshortcircuitcurrent.Exemplarily, the switch 9 and thus the current brea kingelement 6 are operated dependent on a temperature o f theenergy storage module 3. As an overheating of the e nergystorage module is an early sign of degradation, i.e . beingindicative of the faulty energy storage module 3, t hetemperature of the energy storage module 3 is monit ored and P2024,0048 WO E / P230173WO01 March 28,2024 -18 - the state ofthe switch 9 isoperated dependenton a temperature ofthe energystorage module 3.Thisadvantageously triggers the current breaking elemen t 6 forisolating the respective energy storage module 3 be forecatastrophicfailure.As the artificial short circuit current varies only in acomparatively small range, the current breaking ele ment 6formed as a fuse can be selected with a required mi nimumbreaking capacityparticularlyeasy.Further,asa sameamount of the artificial short circuit flows throug h theenergy storage module 3 and the current breaking el ement 6, abreaking currentofthe currentbreaking element6 can beadvantageously selected to break the current to avo id severeheating of the energy storage module 3 and the swit ch 9.The switches 9 of the energy storage system 1 accor ding toFigures 3 and 4 are formed of power semiconductor s witches 9,such asMOSFETs orIGBTs.Particularly,the energy storagesystem 1 corresponds to the energy storage system 1 describedin connection with Figure 1. For example, each of t he powersemiconductor switches 9 intrinsically comprises an anti-parallel diode 15. Advantageously, for an energy ba lancingbetween the energystorage modules3,the switches 9 can beoperated in a modulated manner to avoid the current breakingelement 6 to be triggered to switch to the opened s tate.Thus, the switches 9 are formed of comparatively fa stbidirectional switches, i.e. the power semiconducto rswitches. The energystorage string 2 comprises,interalia, a firstenergy storage module 3, a second energy storage mo dule 3 anda third energystorage module 3.The second energy storage P2024,0048 WO E / P230173WO01 March 28,2024 -19 -module 3 is directly adjacent to the first energy s toragemodule 3 and the third energy storage module 3, i.e . thesecond energy storage module 3 is arranged in serie s betweenthe first energy storage module 3 and the third ene rgystorage module 3. Exemplarily, the second energy st oragemodule 3 is degraded more than the first energy sto ragemodule 3 and the third energy storage module 3. For example,due to thisdegradation,the second energystorage module 3experiences more capacity loss and a higher equival ent seriesresistance compared to the other energy storage mod ules 3.This results, e.g. during a charging process, in th at avoltage of the second energy storage module 3 rises at afaster rate than a voltage of the other energy stor agemodules 3, e.g. reaching the maximum permissible vo ltage. Atthe same time, the other energy storage modules 3 a reundercharged, leading to an underutilization of the capacityofthe energystorage system 1.For transferring energy from the second energy stor age module3, being particularly overcharged, to the first and thirdenergy storage modules 3, initially, the switch 9 i s operatedto be in the closed state for establishing a curren t path asindicated in Figure 3. In particular, energy of the secondenergy storage module 3 is stored in the respective inductors12.Particularly, the switch 9 corresponding to the fau lty secondenergy storage module 3 is closed for a time interv al. Thetime interval is determined such that an accumulate d value ofthe artificial short current is smaller than a thre sholdvalue, wherein the threshold value is, for example,characteristic of a breaking current limit of the c urrentbreaking element6. P2024,0048 WO E / P230173WO01 March 28,2024 -20 - Subsequently,asindicated in Figure 4,the switch 9 ofthesecond energy storage module 3 is opened for a furt her timeinterval, such that electric energy of the at least oneenergy storage module 3 is released from the respec tiveimpedance line 11 to the atleastone otherenergy storage module 3.Once the switch 9 is in the opened state, an induct or currentisfreewheeled through the anti-paralleldiodes15 oftheswitches 9 corresponding to the first and third ene rgystorage modules3.Exemplarily, as the energy is transferred to the tw o directlyneighboring energy storage modules 3, e.g. to the f irst andthird energystorage modules3,partofthe energy istransferred back and forth before a balancing is ac hieved.In contrast to the energy storage system 1 accordin g toFigure 1,the energystorage system 1 according to Figure 5comprises a further parallel line with further swit ches 17being connected in series, wherein each further swi tch 17 isconnected in parallel with a respective energy stor age module3 and a respective current breaking element 6. Each furtherswitch 17 is connected to one of the current breaki ngelements 6 by a further impedance line 19. In parti cular,every second impedance line 11 comprises the induct or 12,every second further impedance line 19 comprises th e furtherinductor 20, and the impedance line 11 comprises th e inductor12 if the further impedance line 19 comprises no fu rtherinductor20. P2024,0048 WO E / P230173WO01 March 28,2024 -21 -Exemplarily, for achieving a comparatively fast bal ancingcompared to the energy storage system 1 of Figure 1 , theenergy storage system 1 of Figure 5 particularly ha s aparallel connection of bidirectional switches, i.e. being theswitches9 and the furtherswitches17.In connection with Figures 6 and 7, a transfer of e nergy isdescribed from the second energy storage module 3 t o thefirst energy storage module 3, and in connection wi th Figures8 and 9, a transfer of energy is described from the secondenergy storage module 3 to the third energy storage module 3,particularly using the energy storage system 1 acco rding toFigure 5.In Figure 7, the switch 9 corresponding to the seco nd energystorage module 3 is in the closed state such that e nergy istransferred from the second energy storage module 3 to therespective inductor12.In Figure 8,the switch 9corresponding to the second energy storage module 3 is in theopened state such that energy is transferred from t herespective inductor12 to the firstenergystorage module 3.In Figure 9, the further switch 17 corresponding to thesecond energy storage module 3 is in the closed sta te suchthat energy is transferred from the second energy s toragemodule 3 to the respective furtherinductor20.In Figure 8,the further switch 17 corresponding to the second e nergystorage module 3 is in the opened state such that e nergy istransferred from the respective further inductor 20 to thesecond energystorage module 3. P2024,0048 WO E / P230173WO01 March 28,2024 -22 -Advantageously, as energy is transferred to only on e directlyneighboring energy storage module 3, balancing is a chievedcomparativelyfast.In contrast to the energy storage system 1 accordin g toFigure 1, the current breaking element 6 of the ene rgystorage system 1 according to Figure 10 is formed a s anisolation switch 9.In contrast to the energy storage system 1 accordin g toFigure 1,the energystorage system 1 according to Figure 11further comprises a resistor 21. The resistor 21 is arrangedbetween two connections 7 of one energy storage mod ule 3.Further, the impedance lines 11 in Figure 11 do not comprisethe inductor12.Particularly, the resistors 21 are configured to di ssipateenergy of the respective energy storage module 3 wi th excessvoltage. The resistors 21 are exemplarily used to d ischargethe respective energy storage module 3 to a voltage levelwhich issafe to handle.The impedance lines 11 in Figure 12 do not comprise theinductor12 asdescribed in Figure 1.The energy storage systems 1 according to Figures 1 3 and 14comprise,in contrastto the energystorage system 1according to Figure 1, a resistor module 22. The re sistormodule 22 is connected to the switch 9, and the res istormodule 22 comprises a resistor 21 and a bypass swit ch 23.In Figure 13, the resistor module 22 is connected i n seriesto the switch 9, and the bypass switch 23 is arrang ed in P2024,0048 WO E / P230173WO01 March 28,2024 -23 -parallel to the resistor 21. In Figure 14, the resi stormodule 22 is connected in parallel to the switch 9, and thebypass switch 23 is arranged in series to the resis tor 21.

[0002] P2024,0048 WO E / P230173WO01 March 28,2024 -24 - Reference Signs 1 energystorage system 2 energystorage string 3 energystorage module 4 firstterminal 5 second terminal 6 currentbreaking element 7 connection 8 parallelline 9 switch 10 interconnection 11 impedance line 12 inductor 13 string current 14 energystorage system isolatorswitch 15 anti-paralleldiode 16 furtherparallelline 17 furtherswitch 18 furtherinterconnection 19 furtherimpedance line 20 furtherinductor 21 resistor 22 resistormodule 23 bypassswitch

Claims

P2024,0048 WO E / P230173WO01 March 28,2024 -25 - Claims 1.Energystorage system (1)comprising -an energystorage string (2)with energystorage modules(3) connected in series through current breaking el ements(6),and- a parallel line with switches (9) being connected inseries,wherein- each energy storage module (3) is connected to on e of thecurrentbreaking elements(6),- each switch (9) is connected in parallel with a r espectiveenergystorage module (3)and a respective current breaking element(6),- the respective switch (9) is configured to provid e acurrentpath through the respective energystorage module (3)and the respective current breaking element (6), an d-the respective switch (9)isconfigured to allow a currentflow through the respective current breaking elemen t (6) todisconnect and bypass the respective energy storage module(3)from the energystorage string (2). 2.Energystorage system (1)according to claim 1, wherein- each switch (9) is connected to one of the curren t breakingelements(6)byan impedance line (11). 3.Energystorage system (1)according to claim 2, wherein- at least one current breaking element (6) is conf igured toelectricallyisolate the respective energystorage moduledependent on a first operational mode of the respec tiveswitch (9),and / or- the impedance lines (11) are configured to transf er energyfrom the respective energy storage module (3) to di rectlyP2024,0048 WO E / P230173WO01 March 28,2024 -26 -neighboring energy storage modules (3) dependent on a secondoperationalmode ofthe respective switch (9).

4. Energy storage system (1) according to one of cl aims 1 to3,wherein -each currentbreaking element(6)isarranged on aconnection (7) between the respective energy storag e module(3)and the respective switch (9).

5. Energy storage system (1) according to one of cl aims 1 to4,wherein -the switch (9)isa powersemiconductorswitch.

6. Energy storage system (1) according to one of cl aims 1 to5,wherein- at least some of the current breaking elements (6 ) comprisea fuse.

7. Energy storage system (1) according to one of cl aims 1 to6,wherein- at least some of the current breaking elements (6 ) comprisean isolation switch.

8. Energy storage system (1) according to one of cl aims 1 to7,wherein- at least some of the impedance lines (11) compris e aninductor(12).

9. Energy storage system (1) according to one of cl aims 1 to8,furthercomprising- a further parallel line with further switches (17 ) beingconnected in series,whereinP2024,0048 WO E / P230173WO01 March 28,2024 -27 -- each further switch (17) is connected in parallel with arespective energy storage module (3) and a respecti ve currentbreaking element(6).

10. Energy storage system (1) according to claim 9, wherein- each further switch (17) is connected to one of t he currentbreaking elements (6) by a further impedance line ( 19),- at least some of the further impedance lines (19) comprisea furtherinductor(20).

11. Energy storage system (1) according to claim 10 , wherein- every second impedance line (11) comprises the in ductor(12),- every second further impedance line (19) comprise s thefurtherinductor(20),and- the impedance line (11) comprises the inductor (1 2) if thefurther impedance line (19) comprises no further in ductor(20).

12. Energy storage system (1) according to one of c laims 1 to11,wherein- a resistor (21) is arranged between two connectio ns (7) ofone energystorage module (3).

13. Energy storage system (1) according to one of c laims 1 to11,wherein- a resistor module (22) is connected to the switch (9), and- the resistor module (22) comprises a resistor (21 ) and abypassswitch (23).

14. Energy storage system (1) according to claim 13 , wherein- the resistor module (22) is connected in series t o theswitch (9),andP2024,0048 WO E / P230173WO01 March 28,2024 -28 -- the bypass switch (23) is arranged in parallel to theresistor(21).

15. Energy storage system (1) according to claim 13 , wherein- the resistor module (22) is connected in parallel to theswitch (9),and- the bypass switch (23) is arranged in series to t heresistor(21).

16. Energy storage system (1) according to one of c laims 1 to15, further comprising a further energy storage str ingconnected in parallelto the energystorage string (2). 17.Method forelectricallyisolating atleastone energy storage module (3)in an energystorage system (1) according to one ofclaims1 to 16,comprising: -closing the switch (9)connected to the atleast one energystorage module (3), such that an artificial short c urrent isgenerated,and- triggering the current breaking element (6) conne cted tothe at least one energy storage module (3) dependen t on theartificialshortcurrent,such that- the at least one energy storage module (3) is ele ctricallyisolated from the other energy storage modules (3).18.Method according to claim 17,wherein- the switch (9) is closed dependent on a monitorin ginformation.

19. Method for transferring energy from at least on e energystorage module (3) to at least one other energy sto ragemodule (3) in an energy storage system (1) accordin g to oneofclaims1 to 16,comprisingP2024,0048 WO E / P230173WO01 March 28,2024 -29 - -closing the switch (9)connected to the atleast one energystorage module (3) for a time interval, such that e lectricenergy of the at least one energy storage module (3 ) isstored in the respective impedance line (11),and- opening the switch (9) of the at least one energy storagemodule (3), such that electric energy of the at lea st oneenergy storage module (3) is released from the resp ectiveimpedance line (11) to the at least one other energ y storagemodule (3). 20.Method according to claim 19,wherein- the time interval is determined such that an accu mulatedvalue of the artificial short current is smaller th an athreshold value.

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