Auxiliary power supply for energy storage system

Abstract

Disclosed is an energy storage system (ESS) (100) comprising an energy storage circuit (122) including a string (111) of interconnected energy storage units (110) configured to store electrical energy and supply power to a power grid using the stored electrical energy. The ESS further comprises an auxiliary module (112) configured to provide an auxiliary function to at least one of the plurality of energy storage units (110), and an auxiliary power circuit (124) for supplying power from a ground power source (126) to the auxiliary module (112). The auxiliary power circuit (124) is configured to galvanically isolate the energy storage circuit (122) from the ground power source (126), thereby preventing an electrical arc discharge between the ESS (100), which may be at a high voltage, and ground at the ground power source (126).

Description

Technical Field

[0001] Technical Field The present disclosure generally relates to an electrical energy storage system. More particularly, the present disclosure relates to an auxiliary power supply device for an electrical energy storage system.

Background Art

[0002] Background An energy storage system (ESS) is a system for storing a large amount of electrical energy. The electrical energy may be generated by inconsistent generation means, and thus the ESS advantageously provides a way to store the generated electrical energy for later use even when the generation means itself is offline. Therefore, the ESS can form an important part of a renewable energy distribution network including, for example, solar power generation or wind power generation.

[0003] The ESS may typically include an energy storage unit (ESU) disposed within a cabinet, and the term "cabinet" can be considered as a collection of interconnected ESUs. Each ESU may include one or more energy storage cells such as (super) capacitors. Therefore, the arrangement of ESUs within the cabinet can advantageously provide a modular ESS.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Summary The present disclosure relates to such an ESS comprising an energy storage circuit including a string of interconnected ESUs configured to store electrical energy and supply power to a power grid using the stored electrical energy.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, the ESS includes an auxiliary module (AM) configured to provide an auxiliary function to at least one of a plurality of energy storage units. The auxiliary function may include, for example, performing measurements (e.g., electrical and / or thermal) within the ESU, monitoring the ESU, e.g., communicating data between the ESU and a central control unit, operating a protection system within the ESU as needed, and / or performing diagnostics.

[0006] To perform such an auxiliary function, the AM may require power. According to a comparative example not necessarily included in the prior art, the power for the AM may be supplied from the ESU itself, e.g., the same ESU that the AM is configured to provide the auxiliary function for.

[0007] However, according to such a configuration, the ESU must be first energized to supply power to the AM. Thus, when the ESU is energized without the AM being able to provide at least some auxiliary functions to the ESU, there may be a time between the energization of the ESU and the power supply from the ESU to the AM. Therefore, the ESU has a specific risk of failure or damage during such a time of initial energization, and the protection, monitoring, and similar auxiliary functions provided by the AM may be deprived during this time.

[0008] Therefore, according to the foregoing aspect of the present disclosure, an auxiliary power supply (APS) circuit for supplying power from a ground power source to the auxiliary module is further provided. In some examples, the ground power source can obtain power from the same power grid that the ESU of the ESS is configured to supply power to, but does not obtain power directly from the ESU itself. In other examples, the ground power source can obtain power from a generator (e.g., a diesel generator, etc.).

[0009] In any case, the use of a grounded power source that does not draw power directly from the ESU can, advantageously, enable the AM to be powered even when the ESU is not energized. Thus, the ESU may be energized and de-energized while the auxiliary function is provided (i.e., electrical energy is supplied to and drawn from it). The ESS can, advantageously, maintain a protection system, a monitoring system, etc. throughout the operation, thereby improving the safety of the operation of the ESS.

[0010] According to a comparative example not necessarily included in the state of the art, the auxiliary power supply circuit can form a direct electrical connection between the grounded power source and the AM. In such an example, since the AM may have a direct electrical connection to the ESU that provides the auxiliary function, the ESS has its ability to reach high voltages limited and may thus potentially be less suitable for use in supporting the power grid.

[0011] Therefore, when the ESU (at a relatively high potential) is electrically connected to the grounded power source via an auxiliary power supply circuit that supplies power to the AM, if the electrical energy stored in the ESU exceeds a threshold amount, there may be a risk of an electrical arc discharge from the ESU to ground (i.e., zero potential).

[0012] In an exemplary ESS configured to supply power to the power grid (i.e., a "grid-supporting ESS") and having ESUs connected to each other on an energy storage circuit, the energy storage circuit can be at a potential of tens to thousands of kilovolts (10s - 100s kV). At such a potential, any component in the path of a direct electrical connection between the energy storage circuit and ground can be severely damaged by an arc discharge. Thus, it is realized as part of the present disclosure that a grid-supporting ESS may require special adaptation to supply power from the grounded power source to the AM within the ESS.

[0013] Accordingly, according to the foregoing aspects of the present disclosure, the auxiliary power supply circuit is configured to galvanically isolate the energy storage circuit from the ground power supply. As used herein, "galvanically isolate" means to electrically connect without a direct conductive path. By galvanically isolating the energy storage circuit from the ground power supply, the AM may be safely powered by the ground power supply even when the ESU is energized to a high potential (i.e., collectively stores an amount of electrical energy suitable for supplying power to the power grid).

[0014] As part of the configuration of the APS circuit for galvanically isolating the energy storage circuit from the ground power supply, the APS may comprise at least one inductive coupling. Thus, the power for the AM may advantageously be sourced from the ground power supply without forming a direct conduction path with the APS circuit, and the APS circuit may be electrically connected or may not be sufficiently isolated from the energy storage circuit.

[0015] The inductive coupling may be a non-resonant inductive coupling, such as an isolation transformer, or a resonant inductive coupling. A resonant inductive coupling may comprise, for example, a transmitter configured to inject a power signal into the energy storage circuit and a receiver configured to receive the power signal in the energy storage circuit and convert the received power signal into power for the auxiliary module.

[0016] The inductive coupling may take any suitable form depending on the desired implementation, taking into account, among other potential consequential factors, the amount of potential that needs to be isolated from ground, the amount of modularization required, the maximum allowable cost, and / or spatial limitations.

[0017] For example, inductive coupling (or other means of galvanic insulation) may be arranged as part of a two-stage insulation. That is, the auxiliary power supply circuit includes a primary unit, a primary circuit, a secondary unit, and a secondary circuit. The primary circuit is galvanically insulated from the ground power supply by the primary unit, the secondary circuit is connected to the auxiliary module, and is galvanically insulated from the primary circuit by the secondary unit. Inductive coupling may be in one or both of the primary unit and the secondary unit.

[0018] As an improvement to such an example, the auxiliary power supply circuit may include a plurality of primary circuits, and each primary circuit is galvanically insulated from the ground power supply by its respective primary unit. Additionally or alternatively, the auxiliary power supply circuit may include a plurality of secondary circuits, and each secondary circuit is galvanically insulated from the primary circuit by its respective secondary unit.

[0019] In some examples, one of the primary circuit or the secondary circuit may be connected to an energy storage circuit, and the other (i.e., the secondary or primary respectively) is connected to the AM.

[0020] As a further example, resonant inductive coupling can inject a power signal having a frequency higher than the characteristic frequency of the power grid (which can be, for example, 50 Hz or 60 Hz). As a result, the transmitter and receiver can transmit and receive more power while beneficially having a smaller form factor.

[0021] In the event of a fault, failure, or (temporary or otherwise) other interruption in the ground power supply, the APS circuit may be further configured to supply power from a backup power supply such that the AM is redundantly powered and the risk of the AM being disadvantaged in terms of power supply is reduced. Thus, the safety of the ESS may be further enhanced. In some examples, the backup power supply may be local to the AM and preferably may comprise an energy storage module from a string of energy storage modules.

[0022] The elasticity of the auxiliary power supply circuit may be further improved by providing a modularized redundant scheme. For example, when multiple primary (and / or secondary) circuits are implemented, the first auxiliary module may be powered via the first primary circuit, and the second auxiliary module adjacent to the first auxiliary module may be powered via the second primary circuit. The same solution can be easily considered for the secondary circuit.

[0023] Therefore, since adjacent AMs are not necessarily all powered on the same circuit, the impact of a failure of any primary (or secondary) circuit can be mitigated. When using the ESU as a backup power supply in combination with the optional features described above, a failed circuit can easily draw power from an adjacent ESU as a backup power supply. Therefore, a more elastic and secure ESS may be provided accordingly.

[0024] The solutions described herein may be applicable to any power grid system that supplies power to and / or draws power from an ESS. By improving the safety and reliability of the ESS, the solutions described herein can, as a result, enhance the reliability of any power grid system in which they are installed.

[0025] Brief Description of the Drawings Next, exemplary embodiments will be described in more detail with reference to the following accompanying drawings.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0027] Detailed Description The present disclosure is explained below by way of several examples. It will be understood that these examples are provided for purposes of illustration and explanation only and are not intended to limit the scope of the present disclosure. Instead, the scope of the present disclosure should be defined by the appended claims. Further, although the examples may be presented in the form of individual embodiments, it will be recognized that the present disclosure also encompasses combinations of the embodiments described herein.

[0028] FIG. 1 schematically shows an energy storage system 100 according to one embodiment of the present disclosure. The energy storage system 100 (ESS100) includes a plurality of energy storage cabinets 102 connected in series (or simply "cabinet 102") to form a bank 104 of energy storage cabinets 102, thereby providing a modular ESS100.

[0029] The bank 104 of the cabinet 102 may be connected between the terminals 106a and 106b such that the bank 104 can be charged and discharged collectively via the terminals 106a and 106b. For example, the terminals 106a and 106b may be connected to the power grid and / or electrical energy generation means (not shown) such that the ESS 100 can store electrical energy (from the electrical energy generation means and / or the power grid) and supply power to the power grid using the stored electrical energy.

[0030] Although only one bank 104 connected in series is shown, it will be understood that additional banks 104 connected either in series or in parallel to the illustrated bank 104 may be provided between the terminals 106a and 106b.

[0031] The ESS 100 may further include a control unit 108 configured to provide various control functions for the ESS 100, such as power management, monitoring, and similar such functions. The control unit 108 may be local or remote to the bank 104 of the cabinet 102 and may be connected (i.e., power connection and / or data connection) via any suitable wired or wireless means.

[0032] In an exemplary implementation, the power generation means may include intermittent renewable electrical energy generation means, such as a wind turbine, a solar panel, that do not consistently generate electricity. In such an implementation, the ESS 100 may advantageously be charged by the electrical energy generation means (i.e., electrical energy is supplied, for example, via the terminals 106a and 106b) while the power generation exceeds the demand from the power grid (i.e., is not immediately used). The electrical energy may then be stored in the ESS 100 for later use.

[0033] Therefore, when the demand from the power grid exceeds the supply capacity of the electrical energy generation means, the supply of electrical energy may be supplemented by using the electrical energy stored in the ESS100. For example, the terminal 106 may be connected to a converter device (such as a STATCOM) configured to supply power to the power grid. Therefore, by incorporating the ESS100 according to the present disclosure, a more flexible power grid may be provided.

[0034] An exemplary configuration of the cabinet 102, such as that shown in FIG. 1, is shown in FIG. 2. As shown, the cabinet 102 may include a plurality of energy storage units 110 (ESU110) arranged in one or more strings 111, and some of the strings 111 of the ESU110 may be connected in parallel with each other, for example.

[0035] An exemplary internal configuration of the ESU110 is shown in an enlarged view, and an auxiliary module 112 (AM112) configured to provide an auxiliary function to the ESU110 is revealed. The ESU may further include a plurality of cells 114, which may be (super) capacitors, batteries, etc., and a protection and bypass system including a discharge resistor 116 and a plurality of switches 118.

[0036] It will be understood that the protection and bypass system shown in FIG. 2 is merely an example of a possible system that may be incorporated into the ESU110 for power flow control and / or protection. Depending on the particular implementation, sensors, monitors, fuses, and / or other control devices, protection devices, or monitoring devices may also be included.

[0037] As shown by the dashed line therefrom, AM112 may be configured to monitor and / or control one or more of the various internal components of ESU110. For example, AM112 may be communicatively coupled to each cell 114 and each switch 118 to identify a failure (or an unintended or otherwise malfunction or other interruption) of cell 114 and execute an appropriate action in response thereto.

[0038] As an example, AM112 can monitor the health of cell 114. If AM112 detects a failure of cell 114, AM112 can control one or more of switches 118 to bypass the failed cell 114 (e.g., the failed cell only, or a group of cells including the failed cell 114), and AM112 can further connect the failed cell 114 to discharge resistor 116 to thereby discharge the failed cell 114, thus making ESU110 safer for maintenance, removal, or replacement.

[0039] Therefore, it will be appreciated that the proper functioning of AM112 can be important for the safe and reliable functioning of ESS100. Failures of cells 114 within ESU110 and other such potential failures within cabinet 102 may be more likely to occur during energization of ESS100 (e.g., during its initial charging). Thus, it may be preferable to ensure that the auxiliary functions provided by AM112 are operational before such energization is initiated.

[0040] Thus, it may be preferable to continuously supply power to AM112, for example via AM power supply 120, or at least ensure that power supplied to AM112 is available before ESU110 is energized.

[0041] Therefore, according to the present disclosure, an auxiliary power supply for the auxiliary module 112 in the ESS100 is provided that reliably supplies power from a power source separate from the ESS100 itself. That is, before the auxiliary function (including monitoring functions and / or protection functions such as those described above) fully operates, the AM112 may require the ESU110 to be energized, so the ESU110 may not be relied upon to supply power to the AM112.

[0042] Therefore, according to the auxiliary power supply configuration described in this specification, the specific examples and variations of which are described below in connection with FIGS. 3 to 7, a safer and more reliable operation of the ESS100 can be guaranteed.

[0043] FIG. 3 schematically shows an exemplary circuit configuration 300 that may be incorporated into an ESS such as the ESS100 described above with respect to FIGS. 1 and 2.

[0044] The circuit configuration 300 may include a string (or a subset of the string) of ESU110s each having an AM112 connected thereto to provide the auxiliary functions, as described above. The AM112 is shown as a separate component from the ESU110, but in some examples, they may be included in the ESU110 as internal components of the ESU110. Further, although each ESU110 is shown to have its own associated AM112, some exemplary embodiments may configure the AM112 to provide auxiliary functions to a plurality of ESU110s.

[0045] The ESU110 is connected via a direct electrical connection on the energy storage circuit 122. The AM112 may be directly electrically connected to the ESU110 and thus to the energy storage circuit 122, or the AM112 may not be sufficiently isolated from the energy storage circuit 122.

[0046] Therefore, when the ESU110 is implemented as part of the power grid system described above, the potential caused by the large amount of electrical energy stored in the ESU110 can be in a high voltage range (i.e., several tens of kV to several hundreds of kV).

[0047] The AM is powered through an auxiliary power supply circuit 124 that can be connected to the energy storage circuit 122 (e.g., via a direct electrical connection). The auxiliary power supply circuit 124 may be configured to supply power from a ground power supply 126 to the AM112.

[0048] By obtaining power from the ground power supply 126, the AM112 can advantageously remain powered regardless of the energization of the ESU110. Thus, the AM112 can be operable to provide auxiliary functions such as protection and monitoring even before and during the initial energization of the ESU110. This may provide a safer and more reliable ESS100.

[0049] Since the ESU110 has such a relatively high potential (with respect to ground, i.e., zero potential), there is a risk of arc discharge between the high potential portion of the energy storage circuit 122 and the auxiliary power supply circuit 124 if it is connected to or not sufficiently insulated from the energy storage circuit 122 and the ground power supply 126.

[0050] As shown, the auxiliary power supply circuit 124 may thus be configured to galvanically isolate the energy storage circuit 124 from the ground power supply 126. As used herein, "galvanically isolating" a circuit from ground means that no direct electrical connection is formed between the circuit and ground.

[0051] In the example shown, galvanic isolation may be provided by a coupling 128 which can be an inductive coupling such as a resonant or non-resonant coupling. It will be appreciated that galvanic isolation may also be provided by a capacitive coupling, a reactive coupling, an optical coupling, or any other such coupling that provides galvanic isolation. However, as part of the present disclosure, it is realized that the coupling 128 can preferably be an inductive coupling that provides a beneficial balance between cost and size. For example, the coupling 128 may be an isolation transformer.

[0052] In the illustrated example of FIG. 3, each AM 112 is directly electrically connected to its respective auxiliary power supply circuit 124, and each auxiliary power supply circuit 124 is galvanically isolated from the ground power supply 126 by its respective coupling 128. In such an example, it will be appreciated that each coupling 128 may be required to ground, i.e., isolate, the overall potential of the energy storage circuit 122 (to which all ESU 110 are connected) from the ground power supply 126.

[0053] That is, each coupling 128 may need to reliably isolate a potential of tens of kV to hundreds of kV from the ground, i.e., prevent an arc discharge across the coupling 128. The size and cost of the coupling 128 can correspond to the amount of potential required to be isolated from the ground. Thus, the exemplary configuration 300 shown in FIG. 3 may be relatively expensive and less space-efficient than those shown in FIGS. 4 - 7.

[0054] FIG. 4 shows an alternative circuit configuration 400 with two-stage insulation. More specifically, as shown in FIG. 4, instead of each coupling 128 being configured to withstand the overall potential of the energy storage circuit 122, only one such configured coupling 128 may be required.

[0055] According to the illustrated configuration 400, the auxiliary power supply circuit 124 includes a primary circuit 124a and a plurality of secondary circuits 124b, and each secondary circuit 124b supplies power from the primary circuit 124a to its respective AM112. The secondary circuit 124b is galvanically isolated from the primary circuit 124a via a secondary coupling 128b (which may also be referred to as a secondary unit 128b), and the primary circuit 124 is galvanically isolated from the ground power supply 126 via a primary coupling 128a (which may also be referred to as a primary unit 128a).

[0056] Each primary coupling 128a and secondary coupling 128b may be similar to the coupling 128 described with respect to FIG. 3, that is, the coupling 128 (which may generically refer to the primary coupling 128a and the secondary coupling 128b) may include, for example, a resonant inductive coupling or a non-resonant inductive coupling.

[0057] However, only the primary coupling 128a may be configured to isolate the overall potential from the ESU110 on the energy storage circuit 122 from the ground potential. That is, the primary coupling 128a can supply power to the primary circuit 124a in a galvanically isolated manner, and then the power may be distributed among the plurality of secondary circuits 124b.

[0058] Therefore, the secondary coupling 124b need not be configured for the entire voltage between the highest voltage of the energy storage circuit 122 and the ground, and may only need to be configured for the voltage between the highest voltage of a subset of the ESU110 and the ground. In this example, since each AM112 for each ESU110 is provided with its own corresponding secondary circuit 124b connected to the primary circuit 124a via its own secondary coupling 128b, the potential isolated from the ground by the secondary coupling 128b may be the potential corresponding to a single ESU110.

[0059] Thus, while cost and space can be saved with respect to the secondary coupling 128b, it will be appreciated that only one more expensive and larger primary coupling 128a may be used.

[0060] In some exemplary variations, a plurality of primary circuits 124a may be provided, each insulated from the ground power supply 126 by respective primary couplings 128a, and each primary circuit 124a may then be coupled to one or more secondary circuits 124b via respective secondary couplings 128b. The secondary circuits 124b can supply power to one or more AMs. In fact, the number of secondary couplings 128b and the way they are connected to the ESU110 (mesh) may be governed by the cost, space limitations, and / or requirements regarding maximum voltage isolation of the secondary circuits 124b.

[0061] Circuit configuration 400 may further include additional components, such as resistor 130 and / or fuse 132, which function as protection means, for example, as desired, in any part thereof.

[0062] Furthermore, in some examples, a bridging connection 133 may be provided across the secondary coupling 128b to boost the potential of the primary circuit 124a, thereby ensuring that most of the galvanic insulation is provided by the primary coupling 128a. This may enable the secondary coupling 128b to be configured to provide galvanic insulation only between one or more adjacent ESU110s.

[0063] FIG. 5 shows a variation of the configuration 400 of FIG. 4. The circuit configuration 500 shown in FIG. 5 uses an alternative connection of the secondary circuits 124b that is different from the connection shown in FIG. 4.

[0064] That is, the secondary circuit 124b within the configuration 400 can distribute power such that each secondary coupling 128b can be configured with the same power rating but may encounter different voltage stresses. In contrast, the secondary circuit 124b within the configuration 500 shown in FIG. 5 can distribute power such that each secondary coupling 128b can be configured with a different power rating but may encounter the same voltage stress.

[0065] Nevertheless, the configuration 500 shown in FIG. 5 can share beneficial characteristics with what was described with respect to FIG. 4 in that, due to the use of two-stage insulation, i.e., the use of the primary circuit 124a and secondary circuit 124b described above, fewer primary couplings 128a (which may be more expensive or larger) may be used. In some examples, depending on the particular implementation, different combinations of the connections described above may be used.

[0066] FIG. 6 shows an alternative circuit configuration 600 comprising a primary circuit 124a and a plurality of secondary circuits 128b sharing the same secondary coupling 128b. According to this illustrated example, the primary coupling 128a and / or secondary coupling 128b may include resonant inductive coupling, which may also be referred to as "wireless power transfer means".

[0067] The primary circuit 124a, the ground-side circuit, and / or the secondary circuit 124b may comprise an additional coupling circuit 134 for activating or enhancing the wireless power transfer means. For example, the coupling circuit may comprise means for changing the signal frequency such that the characteristic frequency of the ground power supply 126 (e.g., the power grid) can be increased. For example, the additional coupling circuit 134 may include a power factor controller (PFC), a rectifier, and / or an inverter.

[0068] Accordingly, the primary coupling 128a and / or the secondary coupling 128b can be made smaller because they can transmit the same power at a higher frequency using a smaller resonant inductive coupling. The wireless power transfer means may be further enabled or enhanced by using a capacitor 136 that can introduce resonance into the circuit. According to such a coupling system, power may be inductively transferred from the transmitting antenna to the receiving antenna through impedance matching.

[0069] FIG. 7 shows a further alternative configuration 700 for the auxiliary power supply circuit 124, where a voltage (e.g., a high-frequency voltage signal), sometimes referred to as a power signal, is superimposed on the operating voltage of the ESU 110 on the energy storage circuit 122, i.e., the voltage associated with the charging and discharging current flow of the ESU 110 during normal operation of the ESS 100.

[0070] Accordingly, the primary circuit 124a including the capacitor 136 may be connected to the energy storage circuit 122 and galvanically isolated from the ground power supply 126 (e.g., an AC power grid) via the primary coupling 128a. The primary coupling 128a may include a transmitter configured to inject a power signal into the energy storage circuit 128a.

[0071] The primary coupling 128a, which may function as a high-frequency external input, may be connected, for example, to the link between two ESUs 110. This connection point for the external input may be the location where the ground voltage of the ESS 100 is lowest. In a monopole system, this can occur at one end of the ESS 100, while in a bipolar system, this point may be the midpoint of the ESS 100. Each primary coupling 128a (e.g., a high-frequency link transfer module) may be equipped with a transformer and a capacitor 136.

[0072] Next, AM112 may be connected to a secondary circuit 124b that is galvanically isolated from the energy storage circuit 122 via a secondary coupling 128b (and thus galvanically isolated from the primary circuit 124a connected thereto). The secondary coupling may include a receiver for receiving a power signal and converting the power signal into power for AM112.

[0073] If AM112 includes components that require DC power, it will be understood that the secondary coupling 128b can be connected to, for example, an AC-DC converter, which can then supply DC power to the secondary circuit 124b.

[0074] The power signal may have a frequency higher than the characteristic frequency of the AC power grid that functions as the ground power supply 126. Thus, the primary coupling 128a and / or the secondary coupling 128b may be made smaller and less expensive than would be required if they were the characteristic frequency of the AC power grid used as the frequency for the power signal.

[0075] It will be understood that all of the concepts disclosed above as alternative configurations may be combined in any manner of compatible methods, depending on the intended implementation.

[0076] Moreover, although schematically shown as being separate, the primary circuit 124a, the secondary circuit 124b, and their respective couplings 128 may be arranged in a single unit or separate units. In some examples, depending on the dielectric strength of the insulator, the secondary circuit 124b and / or the secondary coupling 128b may remain floating. This may result in both the primary coupling 128a and the secondary coupling 128b contributing to providing voltage isolation between the ESU110 and the ground power supply 126.

[0077] It may also be possible to have a common shield for the secondary circuit 124b and / or the secondary coupling 128b and connect this to a point within a sub-section of the ESU 110. In such a configuration, the secondary coupling 128b may only be required to provide voltage isolation between this connection point and the ESU 110 that is furthest vertically from said connection point.

[0078] Although some embodiments and their exemplary modifications may be presented separately herein, it will be understood that these embodiments and examples can be combined in any form to realize their collective and / or synergistic advantages.

[0079] It will be understood that any combination of the above-described exemplary embodiments can advantageously enable powering the auxiliary module 112 for the ESU 110, which may have a very high potential (or "in a situation"). According to the present disclosure, this advantage may be realized by transferring power from the grounded power supply 126 through some means of galvanic isolation (e.g., the coupling 128).

[0080] In any case, it will be understood that the above description only lists some cases that fall within the scope of the present disclosure without necessarily defining its full scope. To avoid misunderstanding, the scope of the present disclosure should be defined by the appended claims.

Claims

1. An energy storage circuit (122) comprising a string (111) of interconnected energy storage units (110) configured to store electrical energy and supply power to a power grid using the stored electrical energy; An auxiliary module (112) configured to provide an auxiliary function to at least one of the plurality of energy storage units (110); An auxiliary power supply circuit (124) for supplying power from a ground power supply (126) to the auxiliary module (112); An energy storage system (ESS) (100) comprising: The auxiliary power supply circuit (124) is configured to galvanically isolate the energy storage circuit (122) from the ground power supply (126); ESS (100).

2. The auxiliary power supply circuit comprises at least one inductive coupling; The ESS according to Claim 1.

3. The at least one inductive coupling includes a resonant inductive coupling; The ESS according to Claim 2.

4. The auxiliary power supply circuit comprises a primary unit, a primary circuit, a secondary unit, and a secondary circuit; The primary circuit is galvanically isolated from the ground power supply by the primary unit; The secondary circuit is connected to the auxiliary module and is galvanically isolated from the primary circuit by the secondary unit; The ESS according to any one of the preceding claims.

5. The auxiliary power supply circuit comprises a plurality of primary circuits, each primary circuit being galvanically isolated from the ground power supply by a respective primary unit; The ESS according to Claim 4.

6. The auxiliary power supply circuit comprises a plurality of secondary circuits, each secondary circuit being galvanically isolated from a primary circuit by a respective secondary unit; The ESS according to Claim 4 or Claim 5.

7. A first auxiliary module is supplied with power via a first primary circuit; A second auxiliary module adjacent to the first auxiliary module is supplied with power via a second primary circuit; The ESS according to Claim 5 or Claim 6.

8. The primary unit and / or the secondary unit comprises a resonant inductive coupling; The ESS according to any one of Claims 4 to 7.

9. The secondary circuit is connected to the energy storage circuit; The ESS according to any one of Claims 4 to 8.

10. wherein the primary circuit is connected to the energy storage circuit The ESS according to any one of claims 4 to 8. **Claim 11** wherein the primary circuit includes a transmitter configured to inject a power signal into the energy storage circuit wherein the secondary circuit includes a receiver configured to receive the power signal from the energy storage circuit and convert the received power signal into power for the auxiliary module The ESS according to claim 10. **Claim 12** wherein the power signal has a frequency higher than the characteristic frequency of the power grid The ESS according to claim 11. **Claim 13** wherein the auxiliary power supply circuit is further configured to supply power from a backup power supply The ESS according to any one of the preceding claims. **Claim 14** wherein the backup power supply includes an energy storage module from the string of energy storage modules The ESS according to claim 13. **Claim 15** A power grid system comprising the ESS according to any one of the preceding claims, wherein the power grid system is configured to receive and distribute electrical energy from the ESS.

Images