Auxiliary power supply of energy storage system

Abstract

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

Description

Technical Field

[0001] The present disclosure generally relates to electrical energy storage systems. More specifically, the present disclosure relates to an auxiliary power supply arrangement for an electrical energy storage system. Background Art

[0002] An energy storage system (ESS) is a system used to store large amounts of electrical energy. The electrical energy may be generated by intermittent power generation, so an ESS conveniently provides a way to store the generated electrical energy for later use as needed, even if the power generation unit itself is offline. An ESS can therefore form an important part of a distribution network that includes renewable energy sources such as solar or wind power.

[0003] An ESS may typically include energy storage units (ESUs) arranged in a cabinet, wherein the term "cabinet" may be considered as a collection of interconnected ESUs. Each ESU may include one or more energy storage cells, such as (super)capacitors, etc. Therefore, arranging the ESUs in the cabinet may advantageously provide a modular ESS. Summary of the invention

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

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

[0006] To perform such auxiliary functions, the AM(s) may require power. According to a comparative example not necessarily included in the prior art, power for the AM may be provided by the ESU itself, for example the same ESU for which the AM(s) are configured to provide auxiliary functions.

[0007] However, according to this arrangement, in order to power the AM, the ESU must first be powered on. Therefore, there may be a period of time between the ESU being powered on and the power being provided from the ESU to the AM, when the ESU is powered on and the AM is unable to provide at least some auxiliary functions to the ESU. Therefore, during this initial power-on time, the ESU may be at particular risk of malfunctioning or being damaged, thereby losing protection, monitoring, and similar auxiliary functions provided by the AM during this time.

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

[0009] Regardless, using a grounded power source that does not draw power directly from the ESU can beneficially allow the AM(s) to be powered even when the ESU is not powered. Thus, the ESU can be powered on and off (i.e., have power provided to it and drawn from it) while still having auxiliary functions provided to it. Thus, the ESS can beneficially maintain protection systems, monitoring systems, etc. throughout operation, thereby increasing the operational safety of the ESS.

[0010] According to a comparative example not necessarily included in the prior art, the auxiliary power supply circuit may form a direct electrical connection between the ground power supply and the (multiple) AM. In such an example, the ESS may be limited in its ability to reach high voltages and may therefore be less suitable for grid support applications because the AM may have a direct electrical connection to the (multiple) ESUs to which it provides auxiliary functions.

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

[0012] In an example ESS, the ESUs are configured to provide power to a grid (i.e., a "grid-supported ESS") and are connected together over an energy storage circuit, which may be at a potential of tens to thousands of kilovolts (10s-100sV). At such potentials, any component in the direct electrical connection path between the energy storage circuit and ground may be severely damaged by an electrical arc. Therefore, as part of the present disclosure, it has been recognized that a grid-supported ESS may require special adaptations to provide power to an AM in the ESS from a grounded power source.

[0013] Therefore, according to the above aspects of the present disclosure, the auxiliary power supply circuit is configured to isolate the energy storage circuit from the ground power supply current. As used herein, "galvanic isolation" means an electrical connection without a direct conduction path. By isolating the energy storage circuit from the ground power supply current, the AM can be safely powered by the ground power supply even if the ESU is powered to a high potential (i.e., collectively storing electrical energy suitable for providing power to the grid).

[0014] As part of the configuration of the APS circuit to galvanically isolate the energy storage circuit from the ground supply, the APS may include at least one inductive coupling. Thus, power for the AM may be advantageously obtained from the ground supply without forming a direct conduction path with the APS circuit (which may be electrically connected to or poorly insulated from the energy storage circuit).

[0015] The inductive coupling may be non-resonant inductive coupling (such as an isolation transformer) or resonant inductive coupling. The resonant inductive coupling may include, for example, a transmitter configured to inject a power signal into an energy storage circuit; and a receiver configured to receive the power signal on 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 several potentially important factors such as the amount of potential isolation from ground that needs to be achieved, the amount of modularity required, maximum allowable cost, and / or space constraints.

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

[0018] As a refinement of this example, the auxiliary power supply circuit may include a plurality of primary circuits, each of which is galvanically isolated from the ground supply by a corresponding primary unit. Additionally or alternatively, the auxiliary power supply circuit may include a plurality of secondary circuits, each of which is galvanically isolated from the primary circuit by a corresponding secondary unit.

[0019] In some examples, either the primary circuit or the secondary circuit may be connected to an energy storage circuit while the other (ie, the secondary circuit or the primary circuit, respectively) is connected to the AM(s).

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

[0021] In the event of a failure, error, or other interruption (temporarily or otherwise) to the ground power source, the APS circuit can be further configured to provide power from the backup power source, so that the AM is redundantly powered and the risk of the AM being powered off is advantageously reduced. Thus, the safety of the ESS can be further enhanced. In some examples, the backup power source can be a local power source for the AM and can preferably include an energy storage module in a string of energy storage modules.

[0022] The resilience of the auxiliary power supply circuit can be further improved by providing a modular redundancy solution. For example, if multiple primary (and / or secondary) circuits are implemented, power can be provided to a first auxiliary module via a first primary circuit, and power can be provided to a second auxiliary module adjacent to the first auxiliary module via a second primary circuit. The same solution can be easily envisioned for the secondary circuits.

[0023] Therefore, the impact of any primary (or secondary) circuit failure can be mitigated because adjacent AMs may not all be powered on the same circuit. If combined with the above optional features, using ESU as a backup power source, the faulty circuit can easily draw power from the adjacent ESU as a backup power source. Therefore, a more resilient and safer ESS can be provided accordingly.

[0024] The solutions described herein can be applied to any grid system that provides power to and / or obtains power from an ESS. By improving the safety and reliability of the ESS, the solutions currently described can therefore enhance the reliability of any grid system where an ESS is installed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments will now be described in more detail with reference to the following drawings, in which:

[0026] Figure 1 schematically illustrates an energy storage system according to an embodiment;

[0027] Figure 2 schematically illustrates an example configuration of an energy storage unit according to an embodiment;

[0028] Figure 3 schematically illustrates an example configuration of an energy storage circuit and an auxiliary power supply circuit according to an embodiment;

[0029] Figure 4 Schematically illustrates another example configuration of an energy storage circuit and an auxiliary power supply circuit with two-level isolation according to an embodiment;

[0030] Figure 5Schematically illustrates another example configuration of an energy storage circuit and an auxiliary power supply circuit having a primary isolation stage and a secondary isolation stage according to an embodiment;

[0031] Figure 6 schematically illustrates another example configuration of an energy storage circuit and an auxiliary power supply circuit having a primary circuit and a secondary circuit according to an embodiment; and

[0032] Figure 7 Another example configuration of an energy storage circuit and an auxiliary power supply circuit using resonant inductive coupling and injected power signals according to an embodiment is schematically illustrated. DETAILED DESCRIPTION

[0033] The present disclosure is unfolded below by way of multiple illustrative examples. It should be understood that these examples are provided only for illustration and explanation, and are not intended to limit the scope of the present disclosure. Rather, the scope of the present disclosure will be limited by the appended claims. In addition, although the examples can be presented in the form of separate embodiments, it should be appreciated that the present disclosure also encompasses the combination of the embodiments described herein.

[0034] Figure 1 An energy storage system 100 according to an embodiment of the present disclosure is schematically shown. The energy storage system 100 (ESS 100 ) may include a plurality of energy storage cabinets 102 (or simply “cabinets 102 ”) connected in series to form a group 104 of energy storage cabinets 102 , thereby providing a modular ESS 100 .

[0035] The group 104 of the cabinets 102 may be connected between the terminal 106a and the terminal 106b, so that the cabinet group 104 may be collectively charged and discharged via the terminals 106a, 106b. For example, the terminals 106a, 106b may be connected to a power grid and / or an electric energy generation device (not shown), so that the ESS 100 may store electric energy (from the electric energy generation device and / or the power grid) and use the stored electric energy to provide power to the power grid.

[0036] It should be understood that although only one cabinet group 104 connected in series is shown, another cabinet group 104 may be provided between the terminal 106 a and the terminal 106 b , and the other cabinet group is connected in series or in parallel with the cabinet group 104 shown.

[0037] The ESS 100 may further include a control unit 108 configured to provide various control functions, such as power management, monitoring, and the like, for the ESS 100. The control unit 108 may be local or remote with respect to the group 104 of cabinets 102 and may be connected (i.e., power and / or data connections) via any suitable wired or wireless means.

[0038] In an example embodiment, the power generation device may include a non-continuous renewable power generation device that cannot generate power continuously, such as a wind turbine, a solar panel, etc. In such an embodiment, during the time when the power generation exceeds the grid demand (i.e., not immediately used), the ESS 100 can be advantageously charged by the power generation device (i.e., provided with power, for example, via terminals 106a, 106b). The power can then be stored in the ESS 100 for later use.

[0039] Accordingly, when the grid demand exceeds the supply capacity of the power generation device, the power stored in the ESS 100 can be used to supplement the power supply. For example, the terminal 106 can be connected to a converter device (such as a STATCOM) configured to provide power to the grid. Therefore, a more flexible grid can be provided by incorporating the ESS 100 according to the present disclosure.

[0040] Figure 2 For example, Figure 1 An example configuration of a cabinet 102 is shown in FIG. As shown, the cabinet 102 may include a plurality of energy storage units 110 (ESUs 110) arranged in one or more strings 111, wherein the plurality of strings 111 of ESUs 110 may be connected in parallel to each other, for example.

[0041] An example internal configuration of the ESU 110 is shown in an enlarged view, showing an auxiliary module 112 (AM 112) configured to provide auxiliary functions for the ESU 110. The ESU may further include a plurality of cells 114 (which may be (super)capacitors, batteries, etc.) and a protection and bypass system (which may include a discharge resistor 116 and a plurality of switches 118).

[0042] It should be understood that Figure 2 The protection and bypass systems illustrated in are merely examples of possible systems that may be incorporated into ESU 110 for controlling and / or protecting the flow of power. Depending on the particular implementation, sensors, monitors, fuses, and / or other control, protection, or monitoring devices may also be included.

[0043] As shown by the dashed lines, the AM 112 may be configured to monitor and / or control one or more of the various internal components of the ESU 110. For example, the AM 112 may be communicatively coupled to each cell 114 and each switch 118 to identify an error (or failure or other interruption (unintentional or otherwise)) of a cell 114 and take appropriate action in response to the error.

[0044] For example, the AM 112 may monitor the health of the cell 114. If the AM 112 detects that the cell 114 is faulty, the AM 112 may control one or more of the switches 118 to bypass the faulty cell(s) 114 (e.g., only the faulty cell or a group of cells including the faulty cell 114), and the AM 112 may further connect the faulty cell(s) 114 to the discharge resistor 116 to discharge the faulty cell(s) 114, thereby making maintenance, removal, or replacement of the ESU 110 safer.

[0045] It should therefore be appreciated that proper operation of the AM 112 may be important to safe and reliable operation of the ESS 100. Failures of cells 114 in the ESU 110, as well as other such potential errors in the cabinet 102, are more likely to occur during power-up of the ESS 100 (e.g., during its initial charging). Therefore, it may be preferable to ensure that the auxiliary functions provided by the AM 112 are operational before initiating such power-up.

[0046] Therefore, it may be preferable to continuously provide power to the AM 112 , for example, via the AM power supply 120 , or at least ensure that power is available to the AM 112 before the ESU 110 is powered on.

[0047] Thus, in accordance with the present disclosure, an auxiliary power supply for an auxiliary module 112 in an ESS 100 is provided that reliably provides power from a power source that is independent of the ESS 100 itself. That is, power may be provided to the AM 112 independent of the ESU 110, which may require the ESU 110 to be powered on before auxiliary functions (including monitoring and / or protection functions, such as those described above) can be fully operational.

[0048] Therefore, according to the auxiliary power configuration described in this article, the ESS100 can be ensured to operate more safely and reliably. Figures 3 to 7 Specific examples and variations of the auxiliary power supply configuration are described.

[0049] Figure 3 An example circuit configuration 300 is schematically shown, which may be incorporated into an ESS (such as described above with respect to Figure 1 and Figure 2 ESS100 described herein.

[0050] The circuit configuration 300 may include a string (or a subset of strings) of ESUs 110, each string having an AM 112 connected thereto for providing auxiliary functions (as described above). In some examples, the AMs 112 are illustrated as separate components from the ESUs 110, but they may also be included as internal components of the ESUs 110. Furthermore, while each ESU 110 is illustrated as having its own associated AM 112, some example embodiments may configure one AM 112 to provide auxiliary functions to multiple ESUs 110.

[0051] The ESU 110 is connected to the energy storage circuit 122 via a direct electrical connection. The AM 112 may be directly electrically connected to the ESU 110 and thus to the energy storage circuit 122, or the AM 112 may be poorly insulated from the energy storage circuit 122.

[0052] Therefore, if the ESUs 110 are collectively implemented as part of a power grid system as described above, the electrical potential caused by the large amount of electrical energy stored in the ESUs 110 may be in the high voltage range (ie, 10s kV to 100s kV).

[0053] The AM is powered via an auxiliary power supply circuit 124, which may be connected (eg, via a direct electrical connection) to the energy storage circuit 122. The auxiliary power supply circuit 124 may be configured to provide power to the AM 112 from a ground power source 126.

[0054] By drawing power from the ground power source 126, the AM 112 may advantageously remain powered regardless of whether the ESU 110 is powered on. Thus, the AM 112 may be operable to provide auxiliary functions such as protection and monitoring even before and during initial power-on of the ESU 110. This may provide a safer and more reliable ESS 100.

[0055] Because the ESU 110 has such a relatively high potential (relative to ground, i.e., zero potential), there is a risk of arcing between the high potential portion of the energy storage circuit 122 (and the auxiliary power supply circuit 124 if it is poorly connected to or insulated from the energy storage circuit 122) and the grounded power supply 126.

[0056] As shown, the auxiliary power supply circuit 124 may therefore 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 is intended to mean that the circuit is not directly electrically connected to ground.

[0057] In the example shown, galvanic isolation can be provided by coupling 128, which can be an inductive coupling such as a resonant or non-resonant coupling. It should be understood that galvanic isolation can also be provided by capacitive coupling, reactive coupling, optical coupling, or other such coupling that provides galvanic isolation. However, as part of the present disclosure, it should be recognized that coupling 128 can preferably be an inductive coupling, which provides a beneficial balance between cost and size. For example, coupling 128 can be an isolation transformer.

[0058] exist Figure 3 In the illustrated example, each AM 112 is electrically connected directly to a respective auxiliary power supply circuit 124, each of which is galvanically isolated from a ground power supply 126 by a respective coupling 128. In such an example, it will be appreciated that each coupling 128 may be required to isolate the total collective potential of the energy storage circuit 122 (to which all of the ESUs 110 are connected) from ground (i.e., the ground power supply 126).

[0059] That is, each coupling 128 may need to reliably isolate a potential of 10s kV to 100s kV from ground, i.e., prevent arcing across the coupling 128. The size and cost of the coupling 128 may be proportional to the amount of potential that needs to be isolated from ground. Figure 3 The example configuration shown in 300 may be more Figures 4 to 7 The configuration shown in is relatively more expensive and less space efficient.

[0060] Figure 4 An alternative circuit configuration 400 including two levels of isolation is shown. More specifically, as Figure 4 As illustrated, rather than every coupling 128 being configured to withstand the collective potential of the energy storage circuit 122, only one coupling 128 so configured may be required to do so.

[0061] According to the illustrated configuration 400, the auxiliary power supply circuit 124 includes a primary circuit 124a and a plurality of secondary circuits 124b, each of which provides power from the primary circuit 124a to a corresponding AM 112. 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).

[0062] Each of the primary coupling 128a and the secondary coupling 128b may be similar to that described with respect to Figure 3 The described coupling 128 , ie, coupling 128 (collectively, primary coupling 128 a and secondary coupling 128 b ) may include, for example, resonant or non-resonant inductive coupling.

[0063] However, only the primary coupling 128a may be configured to isolate the collective potential of the ESU 110 from the energy storage circuit 122 from ground potential. That is, the primary coupling 128a may provide power to the primary circuit 124a in a galvanically isolated manner and thereafter may distribute the power among the plurality of secondary circuits 124b.

[0064] Therefore, the secondary coupling 124b may not need to be configured for the entire voltage between the highest voltage of the energy storage circuit 122 and ground, but only for the voltage between the highest voltage of a subset of the ESUs 110 and ground. In this example, the voltage potential isolated from ground by the secondary coupling 128b can be the voltage potential corresponding to a single ESU 110, because each AM 112 of each ESU 110 is provided with its own corresponding secondary circuit 124b, which is connected to the primary circuit 124a via its own secondary coupling 128b.

[0065] Therefore, it will be appreciated that the cost and space of the secondary coupling 128b may be saved while only one more expensive and larger primary coupling 128a may be used.

[0066] In some example variations, a plurality of primary circuits 124a may be provided, each of which is isolated from the ground power source 126 by a corresponding primary coupling 128a, and each primary circuit 124a may then be coupled to one or more secondary circuits 124b via a corresponding secondary coupling 128b. The secondary circuits 124b may provide power to one or more AMs. In practice, the number of secondary couplings 128b and the manner in which they are connected to the ESU 110 (grid) may be constrained by cost requirements, space limitations, and / or the maximum voltage isolation of the (multiple) secondary circuits 124b.

[0067] The circuit configuration 400 may further include additional components such as a resistor 130 and / or a fuse 132 at any portion thereof as desired, for example, to serve as protective measures.

[0068] Additionally, in some examples, a bridge connection 133 may be provided across the secondary coupling 128b to strengthen the potential of the primary circuit 124a, thereby ensuring that most of the galvanic isolation is provided by the primary coupling 128a. This may allow the secondary coupling 128b to be configured to provide galvanic isolation only between one or more adjacent ESUs 110.

[0069] Figure 5 Pictured Figure 4 A variation of configuration 400 . Figure 5 The circuit configuration 500 shown in FIG. 1 employs an alternative connection of the secondary circuit 124 b to Figure 4 The connections shown in are different.

[0070] That is, the secondary circuits 124b in configuration 400 may distribute power such that each secondary coupling 128b may be configured to have the same power rating but may be subject to different voltage stresses. Figure 5 The secondary circuits 124b in the configuration 500 shown in FIG. 5 may distribute power such that each secondary coupling 128b may be configured to have a different power rating but may be subject to the same voltage stress.

[0071] despite this, Figure 5 The configuration 500 shown in FIG. Figure 4 The beneficial properties discussed are that fewer primary couplings 128a (which may be more expensive or larger) may be used due to the use of two-stage isolation (i.e., the use of (multiple) primary circuits 124a and (multiple) secondary circuits 124b as discussed above). In some examples, a combination of the different connections described above may be used, depending on the particular implementation.

[0072] Figure 6 An alternative circuit configuration 600 is shown that includes one primary circuit 124a and multiple secondary circuits 128b that share the same secondary coupling 128b. According to the illustrated example, the primary coupling 128a and / or the secondary coupling 128b may include a resonant inductive coupling, which may also be referred to as a "wireless power transfer device."

[0073] The primary circuit 124a (circuit on the ground side) and / or the secondary circuit 124b may include an additional coupling circuit 134 for starting or enhancing the wireless power transmission device. For example, the coupling circuit may include a device for changing the signal frequency so that the characteristic frequency of the ground power source 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.

[0074] Therefore, the size of the primary coupling 128a and / or the secondary coupling 128b can be reduced because the same power can be transmitted at a higher frequency using a smaller resonant inductive coupling. By using the capacitor 136, resonance can be introduced into the circuit, thereby further enabling or enhancing the wireless power transmission device. According to this coupling system, power can be inductively transmitted from the transmitting antenna to the receiving antenna via impedance matching.

[0075] Figure 7Another alternative configuration 700 of the auxiliary power circuit 124 is illustrated, with a voltage (e.g., a high frequency voltage signal, which may also be referred to as a power signal) superimposed on the operating voltage of the ESU 110 on the energy storage circuit 122, i.e., the voltage associated with the flow of current that charges and discharges the ESU 110 during normal operation of the ESS 100.

[0076] Thus, the primary circuit 124a including the capacitor 136 can be connected to the energy storage circuit 122 and galvanically isolated from the ground power source 126 (e.g., AC grid) via the primary coupling 128a. The primary coupling 128a can include a transmitter configured to inject a power signal into the energy storage circuit 128a.

[0077] The primary coupling 128a can be used as a high frequency external input, for example, it can be connected to the link between two ESUs 110. Therefore, the connection point of this external input can be the location where the ESS 100 has the lowest voltage to ground. In a monopole system, this may occur at one end of the ESS 100, while in a bipole system, this point may be the midpoint of the ESS 100. Each primary coupling 128a (e.g., a high frequency link transmission module) can be equipped with a transformer and capacitor 136.

[0078] The AM 112 may then be connected to a secondary circuit 124 b that is galvanically isolated from the energy storage circuit 122 (and thus from the primary circuit 124 a connected to the energy storage circuit) via a secondary coupling 128 b. The secondary coupling may include a receiver that receives the power signal and converts the power signal into electrical power for the AM 112.

[0079] It should be appreciated that if the AM(s) 112 include components requiring DC power, the secondary coupling(s) 128b may be connected to, for example, an AC-DC converter which may then feed DC power to the secondary circuit 124b.

[0080] The frequency of the power signal may be higher than the characteristic frequency of the AC grid used as ground power source 126. Therefore, primary coupling 128a and / or secondary coupling 128b may be made smaller and cheaper than required when the characteristic frequency of the AC grid is used as the frequency of the power signal.

[0081] It will be appreciated that all concepts disclosed above as alternative configurations may be combined in any compatible manner, depending on the intended implementation.

[0082] In addition, although schematically illustrated as separate, the primary circuit 124a and the secondary circuit 124b and their respective couplings 128 may be placed in one unit, or in separate units. In some examples, depending on the dielectric strength of the insulation, the secondary circuit 124b and / or the secondary coupling 128b may remain floating. This may allow both the primary coupling 128a and the secondary coupling 128b to help provide voltage isolation between the ESU 110 and the ground power supply 126.

[0083] A common shield may also be provided on the secondary circuit 124b and / or the secondary coupling 128b and connected to a point in the ESU 110 subdivision. In such a configuration, the secondary coupling 128b may only need to provide voltage isolation between that connection point and the ESU 110 that is farthest vertically from that connection point.

[0084] While some embodiments and example modifications thereof may have been presented independently herein, it should be understood that these embodiments and examples may be combined in any form so as to achieve collective and / or synergistic advantages therefrom.

[0085] It should be understood that any combination of the above example embodiments can advantageously allow for powering auxiliary modules 112 of ESU 110, which can be at (or "at") very high potentials. According to the present disclosure, this advantage can be achieved by transmitting power from grounded power source 126 via some galvanic isolation means (e.g., coupling 128).

[0086] In any case, it should be understood that the foregoing description merely lists a number of illustrative examples that fall within the scope of the present disclosure and does not necessarily limit its full breadth. For the avoidance of doubt, the scope of the present disclosure will be defined by the appended claims.

Claims

1. An energy storage system (ESS) (100), comprising: an energy storage circuit (122), the energy storage circuit comprising a plurality of energy storage units (110) interconnected in a series (111), the plurality of energy storage units being configured to store electrical energy and to use the stored electrical energy to provide power to a grid; an auxiliary module (112) configured to provide auxiliary functions for at least one of the plurality of energy storage units (110); as well as an auxiliary power supply circuit (124), the auxiliary power supply circuit being used to provide power to the auxiliary module (112) from a ground power supply (126); The auxiliary power supply circuit (124) is configured to galvanically isolate the energy storage circuit (122) from the ground power supply (126).

2. The ESS according to claim 1, wherein: The auxiliary power supply circuit includes at least one inductive coupling.

3. The ESS according to claim 2, wherein: The at least one inductive coupling comprises a resonant inductive coupling.

4. An ESS according to any preceding claim, wherein: The auxiliary power supply circuit includes a primary unit, a primary circuit, a secondary unit and a secondary circuit; The primary circuit is galvanically isolated from the ground supply by the primary unit; and The secondary circuit is connected to the auxiliary module and is galvanically isolated from the primary circuit by the secondary unit.

5. The ESS of claim 4, wherein: The auxiliary power supply circuit comprises a plurality of primary circuits, each of which is galvanically isolated from the ground supply by a respective primary unit.

6. An ESS according to claim 4 or claim 5, wherein: The auxiliary power supply circuit comprises a plurality of secondary circuits, each of which is galvanically isolated from the primary circuit by a corresponding secondary unit.

7. An ESS according to claim 5 or claim 6, wherein: providing power to a first auxiliary module via a first primary circuit; and Power is provided to a second auxiliary module adjacent to the first auxiliary module via a second primary circuit.

8. The ESS according to any one of claims 4 to 7, wherein: The primary unit and / or the secondary unit comprises a resonant inductive coupling.

9. The ESS according to any one of claims 4 to 8, wherein: The secondary circuit is connected to the energy storage circuit.

10. The ESS according to any one of claims 4 to 8, wherein: The primary circuit is connected to the energy storage circuit.

11. The ESS of claim 10, wherein: The primary circuit includes a transmitter configured to inject a power signal into the energy storage circuit; and 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.

12. The ESS of claim 11, wherein: The frequency of the power signal is higher than the characteristic frequency of the power grid.

13. An ESS according to any preceding claim, wherein: The auxiliary power supply circuit is further configured to provide power from a backup power source.

14. The ESS of claim 13, wherein: The backup power source includes an energy storage module from the string of energy storage modules.

15. A power grid system comprising an ESS according to any preceding claim, wherein: The grid system is configured to receive and distribute electrical energy from the ESS.

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