Large-scale energy storage modules

Abstract

A module (100) for use in an energy storage system is provided, the module including a first terminal (110) and a second terminal (112), a supercapacitor branch (120) including an array (122) of one or more supercapacitors (124), and a resistive bypass branch (130) including at least a first bypass switch (132) and a resistor (134) connected in series. The supercapacitor branch and the resistive bypass branch are connected in parallel between the first and second terminals. A method of control of such a module, and an energy storage system including several such modules are also provided.

Description

[Technical field]

[0001] Technical Field The present disclosure relates generally to the field of energy storage for power grid stabilization. In particular, the present disclosure relates to handling faults in energy storage systems. [Background technology]

[0002] background Stabilizing the power grid can be a challenge because both the production and consumption of electrical energy vary over time. To compensate for various peaks in production and consumption, modern power grids may include various forms of energy storage, where energy produced during periods of low demand is stored at least temporarily and can be released later during subsequent periods of high demand. Such energy storage may include everything from large hydroelectric dams to small battery banks.

[0003] As an alternative to rechargeable batteries, supercapacitors have been presented as a viable option. Due to their structure, supercapacitors can accept and release charge faster than rechargeable batteries and can also withstand more charge and discharge cycles. To allow for increased storage capacity, multiple supercapacitors can be connected together (in series and / or parallel) to form large-scale energy storage systems.

[0004] However, large scale energy storage based on supercapacitors can also pose challenges in both fault protection capabilities and the ability to provide uninterrupted service in the event of a fault. Summary of the Invention [Means for solving the problem]

[0005] overview To at least partially overcome the above problems, the present disclosure provides a module for use in an energy storage system (and a method of operating / controlling same), and an energy storage system as defined by the independent claims. Further embodiments of the module, the energy storage system and the method are defined by the dependent claims.

[0006] According to a first aspect of the present disclosure, a module for use in an energy storage system is provided. The module comprises a first terminal and a second terminal, through which the module may be connected, for example, to one or more other modules and / or a power grid. The module further comprises a supercapacitor branch comprising an array of one or more supercapacitors. The module further comprises a resistive bypass branch comprising at least a first bypass switch and a resistor connected in series. Within the module, the supercapacitor branch and the resistive bypass branch are connected in parallel between the first terminal and the second terminal.

[0007] The term "supercapacitor" as used herein refers to a capacitor that has a higher capacitance value but a lower voltage limit than a normal capacitor. Such supercapacitors bridge the gap between normal (electrolytic) capacitors and rechargeable batteries. Supercapacitors are sometimes also called "ultracapacitors" or "electrochemical double layer capacitors (EDLCs)."

[0008] In the event of a fault in a module (such as, for example, a short across one or more of the supercapacitors in the supercapacitor branch), a bypass switch may be closed so that the remaining energy of the supercapacitor branch may be discharged / depleted via a resistor. By reducing or depleting the energy in the failed module, the fault may be cleared and, for example, operation of the energy storage system of which the module forms a part may continue to operate as intended, at least temporarily.

[0009] In one or more embodiments, the module may further comprise a direct bypass branch including at least a second bypass switch. The direct bypass branch may also be connected in parallel with the supercapacitor branch and the resistive bypass branch between the first terminal and the second terminal. As used herein, the term "direct bypass branch" refers to a branch that does not rely on (or does not include) a series connected resistor as found in a resistive bypass branch.

[0010] The direct bypass branch can be activated (by closing the second bypass switch) to completely bypass the module and the supercapacitor branch. This may be done, for example, after sufficient energy has been discharged / depleted through a resistor in the resistive bypass branch. For example, it can be envisaged to bypass the module / supercapacitor branch by first closing the first bypass switch, discharging the energy through a resistor, and then closing the second bypass switch once sufficient energy has been discharged. Herein, sufficient energy has been discharged / depleted, for example, to accommodate a situation where the remaining energy in the supercapacitor branch is low energy, so that closing the second bypass switch does not pose any safety risk.

[0011] As used herein, a "bypass switch" refers to a switch that is at least sufficient to close a circuit, but not necessarily sufficient to open a circuit. In other words, a bypass switch does not necessarily have to be a circuit breaker capable of interrupting a high current path.

[0012] In one or more embodiments, the module may be such that there is no fuse or similar component connected in series with the array of one or more supercapacitors and any one of the first terminal and the second terminal.

[0013] The present disclosure provides the insight that, for example, using a supercapacitor instead of a conventional rechargeable battery makes it possible to avoid the need to insert fuses or the like in the supercapacitor branch, thereby reducing circuit complexity and, for example, reducing manufacturing costs.

[0014] In one or more embodiments, the module may be such that there is no switch or circuit breaker in series with the array of one or more supercapacitors and any one of the first and second terminals, which may further reduce circuit complexity and manufacturing costs.

[0015] In one or more embodiments, the module may be such that there is no fuse, switch, or circuit breaker in series with the array of one or more supercapacitors and any one of the first and second terminals, which can further reduce complexity and manufacturing costs.

[0016] In one or more embodiments, the module may be such that an array of one or more supercapacitors is connected directly between the first terminal and the second terminal, i.e., without any other electrical components (such as switches, breakers, fuses, resistors, etc.) therebetween, which can further reduce circuit complexity and manufacturing costs.

[0017] In one or more embodiments, the module may further comprise an array of diodes, wherein within the array, each diode may be reverse connected across at least one supercapacitor of the one or more supercapacitors.

[0018] The array of diodes can be provided to prevent excessive voltage from being applied across the supercapacitor, for example during discharge when the first bypass switch is closed. The applied negative voltage can be limited, for example, by the forward voltage of the diodes.

[0019] In one or more embodiments, the one or more supercapacitor arrays may include two or more supercapacitors connected in series. The number of supercapacitors may be selected to meet particular requirements, such as for storage voltage capacity, and it is envisioned that higher such voltages may be obtained by series connection of multiple supercapacitors.

[0020] In one or more embodiments, the one or more supercapacitor arrays may include two or more supercapacitors connected in parallel. The number of supercapacitors may be selected to meet particular requirements, such as for current supply capacity, and it is envisioned that higher such current supply capacities may be obtained by parallel connection of multiple supercapacitors.

[0021] Of course, combinations of series and parallel connections of multiple supercapacitors are also envisioned. For example, a particular storage voltage may be obtained by a particular number of strings of supercapacitors connected in series. A particular current supplying capacity may be obtained by a particular number of such strings connected in parallel. Of course, other variations are also envisioned.

[0022] According to a second aspect of the present disclosure, there is provided a method of operating a module according to the first aspect (or any embodiment thereof). The method includes detecting the occurrence of a fault associated with one or more supercapacitors of the module. The method further includes lowering remaining energy in the one or more supercapacitors by closing a first bypass switch, thereby discharging the one or more supercapacitors through / via a resistor.

[0023] As previously described herein, such methods can sufficiently reduce the remaining energy in the supercapacitor branch of a module such that a fault in the module can be prevented from adversely affecting other modules in the energy storage system.

[0024] The detection of the fault can be performed, for example, by a controller and / or based on internal diagnostics of the supercapacitors. For example, a short circuit fault may be detected by measuring the voltage across one or more supercapacitors and indicated by a (sudden) decrease in such voltage due to a short circuit. Generally, in this specification, a "fault in a module" or a "fault associated with one or more supercapacitors" may also include faults other than short circuits, such as, for example, loss of communication with a control unit, overheating of a supercapacitor or a busbar, etc. Although not explicitly mentioned in this specification, other faults are also envisaged that may be addressed by closing the first bypass switch and discharging the energy of the supercapacitor by using a resistor.

[0025] In one or more embodiments, the method may further include determining whether a remaining energy in the one or more supercapacitors is below a particular threshold. Upon determining that the remaining energy is below the particular threshold, the method may further include directly bypassing the one or more supercapacitors by closing a second bypass switch.

[0026] In one or more embodiments, the fault may be a short circuit across at least one of the one or more supercapacitors.

[0027] According to a third aspect of the present disclosure, an energy storage system is provided. The energy storage system comprises a plurality of modules of the first aspect (or any embodiment thereof) and a control means (e.g., a computer-implemented controller) for controlling at least one of the modules according to the method of the second aspect (or any embodiment thereof). In this specification, it is assumed that the "control means" includes all means necessary for both detecting faults and commanding and controlling, for example, various bypass switches.

[0028] In one or more embodiments, the energy storage system further comprises at least a second plurality of modules according to the first aspect (or any embodiment thereof) connected in series, the first plurality of modules and the second plurality of modules being connected in parallel as previously described herein.

[0029] The present disclosure relates to all possible combinations of the features recited in the claims. Objects and features described according to the first aspect may be combined with or substituted for objects and features described according to the second and / or third aspect, and vice versa.

[0030] Further objects and advantages of various embodiments of the present disclosure are described below with reference to exemplary embodiments.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments are described below with reference to the accompanying drawings. [Brief description of the drawings]

[0032] [Figure 1a] 1A-1D are schematic diagrams illustrating various exemplary embodiments of modules for use in an energy storage system according to the present disclosure. [Figure 1b] 1A-1D are schematic diagrams illustrating various exemplary embodiments of modules for use in an energy storage system according to the present disclosure. [Figure 1c]1A-1D are schematic diagrams illustrating various exemplary embodiments of modules for use in an energy storage system according to the present disclosure. [Figure 1d] 1A-1D are schematic diagrams illustrating various exemplary embodiments of modules for use in an energy storage system according to the present disclosure. [Figure 1e] 1A-1D are schematic diagrams illustrating various exemplary embodiments of modules for use in an energy storage system according to the present disclosure. [Figure 2a] 1A-1D are schematic flow diagrams of various exemplary embodiments of methods for operating a module according to the present disclosure. [Figure 2b] 1A-1D are schematic flow diagrams of various exemplary embodiments of methods for operating a module according to the present disclosure. [Diagram 3] FIG. 1 illustrates a schematic diagram of an exemplary embodiment of an energy storage system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] In the drawings, like reference numbers are used for like elements unless otherwise noted. Unless expressly stated to the contrary, the drawings show only the elements necessary to illustrate the exemplary embodiments, while other elements may be omitted or only suggested for clarity. As shown in the figures, the sizes of elements and areas may be exaggerated for illustrative purposes and thus provided to illustrate the general structure of the embodiments.

[0034] Detailed Description Next, with reference to Figures 1a-1e, the modular concept according to the present disclosure will be described in more detail.

[0035] 1a illustrates generally an exemplary embodiment of a module 100 that may be included as part of an energy storage system (not shown). The module 100 includes a first terminal 110 and a second terminal 112. The terminals 110 and 112 may be used to connect the module to one or more other modules and / or to a power grid, for example, as part of an energy storage system.

[0036] The supercapacitor branch 120 is connected between the first terminal 110 and the second terminal 112 and includes an array 122 including at least one supercapacitor 124. Although only a single supercapacitor 124 is shown in FIG. 1a in the module 100, it is envisioned that the array 122 may also include two or more supercapacitors. If so, the supercapacitors 124 in the array 122 in the supercapacitor branch 120 may be connected in series and / or parallel as needed to meet particular voltage and / or current supply requirements.

[0037] A resistive bypass branch 130 is also connected between the first terminal 110 and the second terminal 112, i.e. in parallel with the supercapacitor branch 120. The resistive bypass branch 130 includes a first bypass switch 132 and a resistor 134 connected in series as shown in FIG.

[0038] As previously described herein, in the event of a fault (e.g., a short circuit) in the array 122 of supercapacitors 124, the remaining energy in the array 122 may be drained / depleted through resistor 134 by closing the first bypass switch 132. This procedure may continue at least until the remaining energy in the array 122 falls below a certain threshold.

[0039] Fig. 1b shows a schematic representation of another exemplary embodiment of the module 101. In addition to the elements / components of the module 100 described with reference to Fig. 1a, the module 101 further comprises a direct bypass branch 140 connected between the first terminal 110 and the second terminal 112 and in parallel with the supercapacitor branch 120 and the resistive bypass branch 130. The direct bypass branch 140 comprises a second bypass switch 142. It is envisaged that when the remaining energy of the array 122 (after being drained / depleted via the resistor 134 due to the closure of the first bypass switch 132) falls below a certain threshold, the second bypass switch 142 is closed, thereby allowing the module 100 to be completely bypassed. By doing so, in case of a fault, the module can be bypassed so as not to interfere with the functioning of other modules, for example in an energy storage system (not shown) of which the module 101 forms part.

[0040] 1a and 1b, it is noted that a fault in the array 122 of modules 100 and 101 can thus be addressed without the need for other components (such as fuses, additional switches, etc.) in series with the array 122, for example in the supercapacitor branch 120. This is a result of the insight that the use of supercapacitors 124, for example instead of conventional rechargeable batteries, as a means for energy storage makes it possible not to include such additional components (such as fuses, for example) in the circuit. As previously described herein, the elimination of such additional components can allow for less complex circuits, for example with a smaller footprint and for example reduced manufacturing costs.

[0041] In some embodiments of the modules 100 and 101, it is assumed that there is at least no fuse connected in series with the array 122 in the supercapacitor branch 120. In some embodiments, it is assumed that there is at least no switch (or circuit breaker) connected in series with the array 122 in the supercapacitor branch 120. In some embodiments, it is assumed that there is neither a fuse nor a switch (or circuit breaker) connected in series with the array 122 in the supercapacitor branch 120. In all such embodiments, "something not in series with the array" should be interpreted as no such "something" being present between the array 122 and either the first terminal 110 or the second terminal 112. Thus, in some embodiments, the array 122 of one or more supercapacitors 124 may be directly connected between the first terminal 110 and the second terminal 112. Of course, "directly" as used herein includes the presence of, for example, connecting wires, bus bars, etc., but does not include additional electrical components such as resistors, switches, fuses, etc.

[0042] As used herein, a "bypass switch" is intended to be, for example, a disconnect switch, a circuit breaker, or an electronic switch. As previously mentioned, such a bypass switch need not necessarily be capable of interrupting larger currents, in which case an electronic switch may suffice, reducing the need for more expensive and complex disconnect switches and / or circuit breakers.

[0043] FIG. 1c illustrates a further exemplary embodiment of the module 102 further including an array 150 of diodes 152 (no branches other than the supercapacitor branch 120 are shown). Each diode 152 is connected in reverse (with respect to polarity) across a respective supercapacitor 124. As previously described herein, the diode array 150 can help prevent damage to the supercapacitor 124 due to a negative voltage that may appear during discharge of the supercapacitor 124 (through a resistor in the resistive bypass branch) during a fault. By connecting the diodes 152 in reverse across the supercapacitor 124, a negative voltage generated during discharge can turn on the diodes 152 and prevent the magnitude of the negative voltage from becoming larger than the forward voltage of the diodes 152.

[0044] 1d and 1e show schematic diagrams of further exemplary embodiments of modules 103 and 104, respectively. In module 103, supercapacitor branch 120 comprises two sub-branches 125 and 126, each comprising a plurality of supercapacitors 124 connected in series. Each sub-branch 125 and 126 is further provided with a respective diode array 155 and 156, each comprising diodes 152 connected in reverse across the respective supercapacitor 124. In module 104, supercapacitor branch 120 comprises series-connected blocks of supercapacitors, each block comprising one or more parallel strings of series-connected supercapacitors 124. For each block, diodes 152 of diode array 150 are connected in reverse across the block. Here, each diode is connected in reverse across two or more supercapacitors.

[0045] It is also envisaged that if no diodes are included, the supercapacitor branches of the modules described herein may still be configured as in modules 103 and / or 104 (i.e. having two parallel sub-branches and / or having a series-connected block of parallel strings of series-connected supercapacitors). Other configurations of the supercapacitor branches 120 are also envisaged, with the supercapacitors 124 in the array 122 being provided and connected to meet the required performance, for example in terms of storage voltage and / or supply current. The idea of ​​using at least a resistive bypass branch (and possibly also a direct bypass branch) applies to all such configurations of the supercapacitor branches 120 described in the embodiments shown in Figures 1c-1e.

[0046] 2a and 2b, a method of operating the modules described herein will now be described in more detail.

[0047] 2a illustrates a schematic flow of an exemplary embodiment of a method 200. In step S210, the method 200 includes detecting whether a fault associated with one or more supercapacitors in the module has occurred. If it is determined that no fault has occurred, the method 200 may continue to monitor the supercapacitors as indicated by arrow 212. On the other hand, if it is determined that a fault has occurred, the method 200 may proceed to a further step S220 as indicated by arrow 214.

[0048] Detecting the fault can be, for example, from the supercapacitor cabinet / system, and may be based, for example, on current and / or voltage measurements, or may be by a battery management system (BMS) based, for example, on internal diagnostics of the supercapacitor. The voltage measurements may indicate, for example, a sudden drop in voltage, which may indicate, for example, that a short circuit has occurred. Similarly, the current measurements may indicate, for example, a sudden increase in current, which may also indicate, for example, a short circuit fault. Whether the voltage will indicate a fault may be worked out according to, for example, specifications provided by the supercapacitor manufacturer, etc. As previously described herein, the fault does not necessarily have to be a short circuit fault. Other types of faults contemplated within the present disclosure include, for example, loss of BMS communication, overheating of the supercapacitor, overheating of the supercapacitor cabinet busbar, etc.

[0049] Step S220 includes lowering the remaining energy in the supercapacitor(s) of the module by closing a first bypass switch in the resistive bypass branch, so that the supercapacitor can be discharged through the resistance of the resistive bypass branch, thereby allowing the fault to be addressed without adversely affecting other modules in the same energy storage system.

[0050] 2b shows a schematic flow of another exemplary embodiment of method 201. In method 201, an additional step S230 includes determining whether the remaining energy in the supercapacitor(s) is below a certain threshold. If it is determined that the remaining energy is still higher than the certain threshold, method 201 can, for example, wait (as indicated by arrow 216) until the threshold is reached. If it is determined that the remaining energy is below the certain threshold, method 201 can proceed to step S240 (as indicated by arrow 218), where the supercapacitor is then directly bypassed by closing a second bypass switch in the direct bypass branch, as previously described herein. The module can then be completely bypassed, and current no longer needs to flow through the resistance of the resistive bypass branch of the module.

[0051] Now referring to FIG. 3, an energy storage system according to the present disclosure will be described. 3 shows a schematic diagram of an energy storage system 300 including a plurality 310 of modules 312 connected in series. The system 300 also includes control means 320 (such as, for example, a computer-implemented controller) for controlling at least one of the modules 312. Although not shown in FIG. 3, the system 300 also includes the necessary means for example to detect whether a fault has occurred within the module 312, and it is therefore envisaged that the control means 320 is such that the module 312 may be controlled according to any one of the methods described herein, for example the methods 200 and 201 described above with reference to FIGS. 2a and 2b. In some embodiments, it is envisaged that the control means 320 may instead form part of the module 312, i.e. each module 312 may have its own internal control means 320.

[0052] The system 300 may be connected to the power grid 330, for example, to achieve stabilization of the power grid 330, for example, when the power demand is high. As an example, during times of low power demand, the energy storage system may receive power from the grid 330 to charge the supercapacitors in the modules 312. During times of high power demand on the grid 330, the increased demand may be compensated by the system 300 instead of providing power from the supercapacitors of the modules 312 to the grid 330. If the power grid 330 is an AC power grid, the connection to the power grid 330 may be achieved via an AC / DC conversion stage 332. Although not explicitly shown in FIG. 3, it is envisaged that such an AC / DC conversion stage 332 may also be connected to the control means 320 for control purposes.

[0053] 3, the system 300 may also include at least one additional plurality 340 of series-connected modules (e.g., as described herein). The additional plurality 340 may be connected in series with the plurality 310.

[0054] In summary, the use of supercapacitors can allow for faster stabilization (e.g., due to a faster response time in terms of charging / discharging the supercapacitor compared to a conventional rechargeable battery) and can also allow for improved reliability since the supercapacitor can handle an increased number of such charge / discharge cycles. The modules and control methods therefor, as well as the energy storage system described herein, provide improved reliability in that a fault (e.g., a short circuit) in the module can be properly handled and the module can even be completely bypassed, so that the operation of other modules is not adversely affected by the occurrence of such a fault, so that the system as a whole can still be available thereafter. Since each module has its own means of handling faults (one or more bypass branches), fault handling can be distributed within the energy storage system. Furthermore, when used, one or more diodes described herein provide additional protection against negative voltages.

[0055] Although the features and elements are described above in particular combinations, each feature or element may be used alone without the other features and elements, or in various combinations with or without the other features and elements.

[0056] Moreover, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the words "comprising" and "including" do not exclude other elements, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

1. A module (100) for use in an energy storage system, comprising: A first terminal (110) and a second terminal (112); a supercapacitor branch (120) including an array (122) of one or more supercapacitors (124); a resistor bypass branch (130) including at least a first bypass switch (132) and a resistor (134) connected in series; Equipped with the supercapacitor branch and the resistive bypass branch are connected in parallel between the first terminal and the second terminal; a direct bypass branch (140) including at least a second bypass switch (142) but not relying on or including a series connected resistor, said direct bypass branch also being connected in parallel with said supercapacitor branch and said resistive bypass branch between said first terminal and said second terminal; the first bypass switch is configured to close in response to an occurrence of a fault associated with the one or more supercapacitors to discharge the one or more supercapacitors through the resistor, thereby reducing remaining energy in the one or more supercapacitors; the second bypass switch is subsequently configured to close to directly bypass the one or more supercapacitors in response to the remaining energy of the one or more supercapacitors being below a certain threshold; There is no bypass switch connected between the first terminal and the second terminal other than the first bypass switch and the second bypass switch. Module (100).

2. 2. The module of claim 1, wherein there is no fuse connected in series with the array of one or more supercapacitors and any one of the first terminal and the second terminal.

3. 3. The module of claim 1, wherein there is no switch or circuit breaker connected between the array of one or more supercapacitors and any one of the first terminal and the second terminal.

4. 2. The module of claim 1, wherein there are no fuses, switches, or circuit breakers connected between the array of one or more supercapacitors and any one of the first terminal and the second terminal.

5. The module of any one of claims 1 to 4, wherein the array of one or more supercapacitors is directly connected between the first terminal and the second terminal.

6. The module (102, 103, 104) of any one of claims 1 to 5, further comprising an array (150) of diodes (152), each diode (152) in the array of diodes being connected inversely across at least one supercapacitor of the one or more supercapacitors.

7. The module of any one of claims 1 to 6, wherein the array of one or more supercapacitors comprises two or more supercapacitors connected in series.

8. The module of any one of claims 1 to 7, wherein the array of one or more supercapacitors comprises two or more supercapacitors connected in parallel.

9. A method (200) of operating a module including a first terminal (110) and a second terminal (112), wherein a supercapacitor branch (120) includes an array (122) of one or more supercapacitors (124), a resistive bypass branch (130) includes at least a first bypass switch (132) and a resistor (134) connected in series, the supercapacitor branch and the resistive bypass branch being connected in parallel between the first terminal and the second terminal, the module further includes a direct bypass branch (140) including at least a second bypass switch (142), the direct bypass branch also being connected in parallel with the supercapacitor branch and the resistive bypass branch between the first terminal and the second terminal, and no other bypass switches are connected between the first terminal and the second terminal other than the first bypass switch and the second bypass switch, the method comprising: a) detecting the occurrence of a fault associated with the one or more supercapacitors (S210); b) reducing the remaining energy in the one or more supercapacitors by closing the first bypass switch (S220), thereby discharging the one or more supercapacitors through the resistor; ci) determining whether the remaining energy in the one or more supercapacitors is below a certain threshold (S230); and c-ii) upon determining that the remaining energy is below the particular threshold, directly bypassing the one or more supercapacitors by closing the second bypass switch (S240); and The method (200).

10. 10. The method of claim 9, wherein the fault is a short circuit across at least one of the one or more supercapacitors.

11. A first module (310) comprising a plurality of modules (312) according to any one of claims 1 to 8 connected in series; and means for carrying out the operations according to the method of any one of claims 9 to 10.

12. 12. The energy storage system (301) of claim 11, further comprising a second module (340) comprising a plurality of modules (312) according to any one of claims 1 to 8 connected in series, the first module and the second module being connected in parallel.

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