Energy storage rack and frame structure with vibration absorption function

Abstract

To improve the seismic performance of energy storage racks, we propose a cubic frame structure designed to absorb and / or dampen seismic vibrations. [Solution] The frame structure is applicable to the energy storage rack of an energy storage system and comprises a bottom frame formed as a single unit, having a plurality of column brackets projecting vertically upward, aligning columns parallel to each other vertically, a plurality of columns attached to a base frame via column brackets, each formed as a hollow profile, and an upper frame attached to each column, wherein the plurality of columns cooperate to provide a plurality of mounting positions configured for receiving and mounting energy storage modules, and passive cooling can be enhanced by placing an auxiliary unit below the bottom frame.

Description

Technical Field

[0001] The present invention relates to a rectangular frame structure for an energy storage rack of an energy storage system. The present invention also relates to an energy storage rack.

Background Art

[0002] In the present disclosure, the terms "high voltage (HV)", "low voltage (LV)", and "extra low voltage (ELV)" follow the general definitions of IEC 61140:2016 "Electrical shock protection - Common aspects for equipment and installations" of the International Electrotechnical Commission (IEC). Therefore, "high voltage" refers to a voltage exceeding 1000 V for alternating current (AC) and exceeding 1500 V for direct current (DC), "low voltage" refers to a voltage of 1000 V or less for AC and 1500 V or less for DC, and "extra low voltage" refers to a voltage of 50 V or less for AC and 120 V or less for DC.

[0003] Patent Document 1 discloses a rack equipped with a liquid cooling system.

[0004] Patent Document 2 discloses a rack adapted to receive one or more components. This rack includes a backplane, a pair of side panels extending from the backplane, and internal support members on each side for receiving and mechanically guiding the initial alignment of the components upon first insertion into the rack. A pair of male connectors attached to the backplane are configured to mate with a corresponding pair of female connectors of each component, and mechanically guide the final alignment of each component as the component is further inserted into the rack. Mechanical guidance may also be provided or reinforced by a connection capable of supplying liquid cooling to the rack. A system including this rack and the components inserted into the rack is also disclosed.

[0005] These racks, commonly known as 19-inch racks, are standard components of data centers for housing, powering, and cooling servers and other IT equipment. More recently, this type of rack has attracted considerable attention in the energy storage sector, particularly in high-voltage systems. These racks can be used to build large-scale capacitor banks with high-speed charging and discharging capabilities, especially for use in high-voltage DC systems, particularly static synchronous compensation (STATCOM). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2004 / 0057211A1 [Patent Document 2] European Patent Application Publication No. 3661339A1 [Overview of the project] [Problems that the invention aims to solve]

[0007] Due to the characteristics of these systems, they must meet certain requirements regarding the damping and mitigation of seismic vibrations, as stipulated in the IEEE recommended seismic design standard for substations, IEEE 693-2018.

[0008] The object of the present invention is to provide a rack structure with improved vibration damping. This object is achieved by the components of the independent claims. Preferred embodiments belong to the components of the dependent claims. [Means for solving the problem]

[0009] The present invention provides a rectangular parallelepiped frame structure configured to absorb and / or dampen seismic vibrations, which is suitable for energy storage racks in energy storage systems, and the frame structure includes the following:

[0010] - A bottom frame formed integrally as a single component, having multiple column brackets that protrude vertically upward, and configured to align columns parallel to each other in the vertical direction.

[0011] - Multiple columns, each mounted to a base frame via column brackets, and each formed as a hollow profile.

[0012] - An upper frame that attaches to each column. These columns work together to provide multiple mounting positions configured for receiving and installing energy storage modules.

[0013] A one-piece molded base frame offers greater rigidity and enhanced stability. Furthermore, vibration transmission differs from that of bolted composite frames. Overall, a base frame allows for better and easier meeting of vibration requirements.

[0014] Preferably, the bottom frame is integrally formed by welding or casting multiple components. For a simpler construction, the bottom frame can be made by welding from plate-like or (hollow) rod-like material. Casting of the bottom frame is also possible.

[0015] Preferably, each column is attached to the bottom frame and / or top frame by multiple bolt fasteners. The bottom frame is a single, integrally formed member, while the column connections allow for some movement, which results in an attenuation effect at the desired frequency.

[0016] Preferably, the upper frame is a single member formed integrally by welding or casting multiple components. Preferably, the upper frame is also integrally formed. This further improves rigidity and vibration energy transmission, thereby improving the desired vibration absorption characteristics.

[0017] Preferably, at least one column bracket has a first leg extending parallel to the short side of the bottom frame and a second leg extending parallel to the long side of the bottom frame, preferably substantially perpendicular to the first leg. Preferably, the first and second legs are in contact with and / or fixed to the respective column, preferably the case sheet member. Preferably, the column bracket is formed at the corner of the bottom frame. Preferably, at least one column bracket is formed at the end of the bottom frame. Preferably, the column bracket includes a third leg extending parallel to and at a distance from the first leg. Preferably, two column members fixed to the column bracket engage with the first and third legs, as well as the respective case sheet members. The column bracket prevents the column from shifting significantly from its mean position. The column bracket essentially functions as a very stiff leaf spring, further improving the vibration absorption of the frame structure.

[0018] Preferably, at least one column includes a case sheet member and a cover sheet member that engage with and / or are fixed to each other to form the column. A column formed from two sheet members not only facilitates manufacturing but also allows for a certain amount of friction within the column, thereby further improving the vibration absorption function of the frame.

[0019] Preferably, the case sheet member includes at least three U-shaped legs to form the channel sidewall and channel bottom. Preferably, the cover sheet member has at least two L-shaped legs, and the cover sheet member closes the channel to form a hollow profile. If necessary, the case sheet member includes a flange portion that partially protrudes inward from one sidewall and parallel to the channel bottom. This configuration allows for the manufacture of a rigid column member with desirable vibration absorption.

[0020] Preferably, at least one column is formed as an integrally molded single member. Preferably, the column includes a reinforcing portion extending parallel to the short side of the column in a cross-sectional view. In another embodiment, the column can be fabricated as a single piece of thicker sheet metal. Thus, the same vibration absorption as that of a column made of multiple parts can be achieved.

[0021] Preferably, the frame structure further has at least one truss member fixed to one end of a column and fixed to the other end or the central portion to form an acute angle with each column. The truss can enhance the rigidity of the overall structure and also make it possible to disperse specific bending moments generated during vibration.

[0022] Preferably, a plurality of high-voltage isolators are fixed to the bottom frame, preferably by welding. The isolators are usually made of ceramic. Due to the integral structure of the bottom frame, it is possible to directly attach in a way that avoids damage during vibration.

[0023] Preferably, the frame structure further has at least one installation position for receiving and installing a rack control unit that controls an auxiliary power supply module and / or an energy storage module disposed below the bottom frame, preferably adjacent to the bottom frame, for supplying auxiliary power in case of a failure of the main power supply. Usually, heavier or larger-mass modules are preferably disposed below the bottom frame and between the high-voltage isolators. Thus, the center of gravity of the entire structure can be lowered, thereby improving the seismic performance.

[0024] The present invention provides an energy storage rack for an energy storage system. The energy storage rack includes a preferred frame structure and a plurality of energy storage modules configured for storing and supplying electric power, and the energy storage modules are mounted at mounting positions provided by the frame structure.

[0025] Preferably, the energy storage module includes an energy storage device containing a supercapacitor.

[0026] Preferably, at least one auxiliary power module and / or at least one rack control unit are installed at the installation location. The auxiliary power module can lower the center of gravity of the energy storage rack, thereby improving the seismic performance. Furthermore, these modules and units usually generate minimal heat, so the heat load can be reduced.

[0027] Preferably, the energy storage module is passively cooled, and preferably a constant temperature gradient is formed across the entire energy storage rack. For example, passive cooling eliminates the need for the power of cooling fans, reducing energy consumption. A constant temperature gradient equalizes the degradation of the energy storage cells, extends the overall lifespan, and facilitates maintenance.

[0028] Preferably, each energy storage module includes a plurality of energy storage cells arranged in a hexagonal closely packed uniform cylindrical pattern or a rectangular pattern. These patterns enable arranging a large number of energy storage cells within the energy storage module while ensuring sufficient air flow for cooling between the energy storage cells.

[0029] Preferably, each energy storage module includes a heat sink disposed on the side facing the outer direction of the energy storage module, preferably the front side or the back side. By arranging the heat sink outside, heat can be directly discharged from the module, further reducing the heat load.

[0030] In one embodiment, the mechanical rack includes a plurality of energy storage modules. The modules may include supercapacitors or hybrid battery cells.

[0031] In one embodiment, the vibration characteristics of the disclosed rack are less than 33 Hz, and the rack design complies with the seismic requirements for moderate seismic inputs in IEEE 693:2018 with 2% damping.

[0032] In one embodiment, the rack includes a welded beam base frame.

[0033] In some embodiments, the rack is provided with diagonal braces on the rear and / or both sides, preferably not on the front.

[0034] In some embodiments, the rack height is minimized by moving all auxiliary equipment to the sides and underside of the framework.

[0035] In some embodiments, the rack does not contain single-purpose steel components; preferably, all components contribute to strengthening the overall structure.

[0036] In some embodiments, the rack is mounted on several high-voltage (HV) insulators, for example, six HV insulators, preferably one at each corner of the rack and one under each intermediate section of a double rack.

[0037] In some embodiments, the proposed rack includes a passive cooling mechanism, which ensures even heat distribution, prevents localized overheating, and guarantees the reliability and long lifespan of the electronic components within the energy storage system.

[0038] In some embodiments, a constant temperature gradient exists throughout the entire rack.

[0039] The proposed mechanical design for the energy storage rack, namely the supercapacitor rack, is seismically resistant and conforms to the IEEE 693:2018 seismic profile standard. Apart from the seismic design, the rack may have a natural cooling mechanism and may preferably lack a housing.

[0040] The proposed rack design is ideal for high-voltage direct current (HVDC) systems, particularly static synchronous compensation systems (STATCOM) and enhanced STATCOM (ESTACOM) systems.

[0041] Typically, a single rack unit consists of a double rack containing space for 20 modules, a master (module) controller, a bypass subassembly, an auxiliary ("aux.") power supply, and a rack control unit.

[0042] The framework dimensions of rack units are largely standardized to 1200mm x 600mm x 2100mm (width (W) x depth (D) x height (H), excluding HV insulators). Energy storage system (ESS) modules are designed to be installed in racks with preferably 19-inch slider spacing, which is generally the primary constraint determining the overall rack dimensions. This disclosure focuses on this implementation because it is the most widely used form factor. However, it should be noted that other dimensional configurations are also generally possible, though less common.

[0043] Preferably, the rack framework is designed to accommodate 20 ESS modules. The modules are mounted on sliding brackets and can be secured with screws from the front. The framework may include two main subassemblies, namely a welded base frame and a sheet metal framework (particularly the columns). Preferably, the rack is of an open type without walls. Thus, the rack is typically capped with an IP00 rating, meaning a level of protection without special protection against solid or liquid ingress.

[0044] The rack has no additional or optional empty space that is not filled with the necessary equipment. In other words, almost the entire volume of the rack is comprised of components without any wasted space. To conform to the seismic profile, the height of the rack should be kept to the absolute minimum possible, and auxiliary equipment should preferably be installed as much as possible on the sides or bottom of the rack, for example, between insulators.

[0045] Minimizing rack height also helps address potential logistical issues such as transportation limitations and maintainability (e.g., fewer pieces of equipment to reach on a mobile platform). Racks are mounted on high-voltage insulators, preferably one at each corner of the rack and two below the middle section of a double rack. Auxiliary power systems and rack control devices are preferably located beneath the rack base frame between the high-voltage insulators. This has been confirmed to be the optimal location in seismic simulations.

[0046] The master control unit can adjust the voltage balance of the cells in the rack. It can be installed in either the top or bottom section. The master control unit is sometimes placed in the top section. In this double-track system, the auxiliary power unit is conceptually preferred to be located at the bottom of the rack for seismic design and stability reasons. A common grounding point used during maintenance is located in the center of the base frame.

[0047] Seismic design considerations include enhancing stability by placing auxiliary units at the bottom. This lowers the system's center of gravity, improving stability and seismic resistance.

[0048] The E-STATCOM system is designed to withstand a moderate seismic profile according to the IEEE 693:2018 seismic profile. To ensure compliance with the standard, a series of seismically specific preliminary simulations were performed during the conceptual phase, resulting in the embodiments of this disclosure.

[0049] Two simulation targets were set according to standard testing. The first target is that the lowest horizontal natural frequency is 33 Hz or higher. Embodiments with vertical natural frequencies below 33 Hz are acceptable. The natural frequencies must conform to the requirements of IEEE 693-2018. Otherwise, vibration loads may be amplified, damaging the system and potentially leading to destructive resonance phenomena.

[0050] The second objective is to ensure that the rack does not fail under a given vibration profile. The vibration profile is located below 33 Hz. Resonances below 33 Hz generally amplify seismic inputs. Simulation results show that the rack design meets seismic requirements under moderate seismic inputs with a 2% damping rate, according to IEEE 693:2018. The countermeasures described here generally shift the resonant frequency. No damage is observed in sine sweep fatigue calculations.

[0051] The simulations yielded features useful from a seismic design perspective. These features include welded beam base frames, diagonal braces on the rear and sides of the framework, high-voltage insulators at corners and optionally in the middle sections, minimizing rack height by moving all auxiliary devices to the sides and bottom of the framework, and / or eliminating single-purpose steel members. All components work together to strengthen the overall structure.

[0052] Furthermore, thermal management is considered in this disclosure. Thermal simulations were performed to evaluate the effectiveness of the current cooling concept for the E-STATCOM double rack design. Efficient thermal management is crucial for ensuring the reliability and lifespan of electronic components within the ESS. A simplified rack model can be used in the simulation to reduce simulation time while maintaining sufficient model accuracy.

[0053] The analysis conditions include a simplified double-rack model for simulation, 20 ESS modules, a top-mounted master control unit and switchgear enclosure assuming worst-case airflow limitations, a 31A RMS load on ESS modules only, a module balancer temperature of 85°C, a module power loss of approximately 15W-18W (cells and busbars only, excluding balancer), modules in end-of-life (EoL) condition, an equivalent series resistance ESR equivalent to 200% of the rated 1-second ESR, a total rack power loss of approximately 300W (cells and busbars only, excluding balancer), an ambient temperature of 26°C, natural convection cooling, a temperature reference including the highest cell temperature, and a rack IP class of IP00.

[0054] Under these and similar conditions, the temperature distribution within a double rack typically exhibits a constant gradient, with natural convection causing the highest temperatures near the top of the rack.

[0055] The maximum observed cell temperature was approximately 48°C, which is within the component's acceptable operating range. This suggests that passive cooling is effectively managing the heat generated by the ESS module. The temperature distribution is relatively uniform throughout the module, with no significant hot spots. Thus, passive cooling ensures even heat distribution and prevents localized overheating.

[0056] Detailed analysis of individual modules, particularly the third module from the top, shows that the temperature in the center is higher than at the edges. This gradient from center to edge is typical of this type of configuration and is manageable within safe limits.

[0057] Life simulations conducted after thermal simulations demonstrated the effectiveness of the passive convection cooling configuration for the E-STATCOM double rack. The study focused on evaluating the temperature rise and thermal resistance (Rth) within the module.

[0058] This section describes the key findings of the thermal studies regarding temperature rise, thermal resistance, and lifetime prediction. The maximum cell temperature observed during the simulation was approximately 48°C. This temperature is well within the allowable operating range of the component. Thermal simulations revealed that the maximum thermal resistance (Rth) value was 1.34 K / W. This value indicates efficient heat dissipation, showing that the system effectively manages the thermal load generated by the module. The Rth value used in the lifetime simulation is selected according to the maximum module temperature value. Based on the temperature rise and calculated thermal resistance, the expected lifetime of the system component is expected to be over 20 years under ambient temperature conditions of 26°C.

[0059] In double-rack designs, precise temperature monitoring is sometimes required to ensure optimal module performance and long lifespan. Temperature sensor placement is strategically designed to obtain accurate thermal data from critical points within the system. The sensors are not directly located on the cells themselves, but rather on the printed circuit board (PCB). Each cell should preferably be numbered using a so-called cell index, and temperature sensors are placed in critical locations for monitoring their thermal state. Specifically, bottom and top temperature sensors are used preferentially. Current measurement (CM) sensors may also be provided to measure the current in the PCB busbars.

[0060] Effective thermal management in this configuration allows for safe operating temperatures to be maintained through a passive cooling system utilizing natural convection, eliminating the need for additional cooling. As a result, extended lifespan and availability of electronic components are ensured.

[0061] Furthermore, the absence of a sealed housing or enclosure contributes to cost efficiency, improved cooling efficiency, and reduced complexity, potentially achieving a system lifespan of 20 years. Compared to forced cooling or liquid cooling solutions, additional costs, increased weight, operational complexity, and potential environmental impacts can also be reduced or avoided.

[0062] The elimination of liquid cooling further reduces the failure rate by eliminating potential points of failure. Overall, this method helps ensure a reliable, efficient, and sustainable thermal management solution in E-STATCOM double-rack systems.

[0063] Embodiments of the present invention will be described in more detail with reference to the accompanying schematic diagrams shown below. [Brief explanation of the drawing]

[0064] [Figure 1] Figure 1 shows an embodiment of an energy storage rack. [Figure 2] Figure 2 shows an embodiment of the bottom frame. [Figure 3] Figure 3 shows another embodiment of the bottom frame. [Figure 4] Figure 4 shows details of the column attached to the bottom frame. [Figure 5] Figure 5 shows an embodiment of the upper frame. [Figure 6] A variation of the column is shown. [Figure 7] A variation of the column is shown. [Figure 8] A variation of the column is shown. [Figure 9] Figure 9 shows another embodiment of the energy storage rack. [Figure 10] Figure 10 shows the spectral acceleration graph of the energy storage rack. [Figure 11A] Figure 11A shows a side view of the thermal simulation results. [Figure 11B] Figure 11B shows a front view of the thermal simulation results. [Figure 12] Figure 12 shows a horizontal cross-sectional view of the thermal simulation results. [Figure 13] Figure 13 shows a table of the thermal simulation results. [Figure 14] Figure 14 shows the location of the thermal sensors in the energy storage module. [Modes for carrying out the invention]

[0065] Figure 1 shows an energy storage rack 10. The energy storage rack 10 includes a frame structure 12. The frame structure 12 supports a plurality of energy storage modules 14 that are mounted on the frame structure at predetermined mounting positions 16. The energy storage modules 14 are electrically and mechanically connected by a plurality of busbars 18.

[0066] The frame structure 12 includes a bottom frame 20. The bottom frame 20 supports a plurality of vertical columns 22. The columns 22 are constrained together at the top by an upper frame 24. The frame structure 12 may also include a plurality of trusses 26 mounted between different columns 22.

[0067] Figure 2 shows the bottom frame 20 in more detail. The bottom frame 20 is a single, integrally formed member. The bottom frame 20 has a generally rectangular shape. The bottom frame 20 is welded from different sheet metal parts. The thickness of the sheet metal is preferably at least 3 mm, and preferably about 5 mm.

[0068] The bottom frame 20 has long front and rear sections 28, 30 and short side sections 32, 34. Furthermore, it includes a crossbeam 36 that is parallel to the side sections 32, 34 and formed approximately in the center.

[0069] The cross-sections of the long front and rear sections 28, 30 and the short side sections 32, 34 are generally C-shaped. These sections 28-34 may include openings for airflow.

[0070] The crossbeam 36 may have a C-shaped cross-section, but other cross-sectional shapes similar to, for example, an I-beam are also possible, and it is preferable that the upper surface is narrower than the lower surface.

[0071] The bottom frame 20 includes multiple high-voltage (HV) isolators 38. The HV isolators 38 are attached to the bottom frame 20 via fasteners and are preferably positioned in the corners 40 and intermediate sections 42, as shown in Figure 2.

[0072] The bottom frame 20 includes a plurality of column brackets 44 that protrude upward. The column brackets 44 are formed in the corner sections 40 and the intermediate sections 42. The column brackets 44 in the corner sections 40 are generally L-shaped, and the column brackets 44 in the intermediate sections 42 are generally U-shaped.

[0073] Figure 3 shows another embodiment of the bottom frame 20. Here, the bottom frame does not have crossbeams, but instead includes a stabilizing plate 37. The stabilizing plate 37 can be welded to the front and rear sections 28, 30 and preferably to the C-shaped short legs. The bottom frame 20 includes four HV isolators 38.

[0074] Referring to Figure 4, the bottom frame 20 is shown in detail. The column bracket 22 includes a first leg 46, a second leg 48, and a third leg 50. The first and third legs 46, 50 are parallel to each other and spaced apart by the second leg 48. The second leg 48 is perpendicular to the first and third legs 46, 50.

[0075] Column 22 includes a case sheet member 52 and a cover sheet member 54. These sheet members 52 and 54 are preferably formed from bent metal plates with a thickness of approximately 3 mm.

[0076] Referring to Figures 4 and 6, the case sheet member 52 generally has a U-shaped cross-section formed by legs 56-60. These three legs 56-60 form the side wall 62 and channel bottom 64 of a channel 66 that opens on one side.

[0077] The case sheet member 52 may have a first flange 68 projecting from one side wall 62 to the other side wall 62 in order to partially cover the opening. The first flange 68 allows the case sheet member 52 to be fixed to the cover sheet member 54 and / or the column bracket 22.

[0078] A second flange 70 may protrude outward from the other side of the side wall 62 and away from the channel 66 on the case sheet member 52. The second flange 70 allows the case sheet member 52 to be fixed to the support rail 72 that supports the energy storage module 14.

[0079] Returning to Figure 4, the cover sheet member 54 has two orthogonal legs 74, 76. The legs 74 are large enough to cover the channel 66, and the case sheet member 52 and the cover sheet member 54 form a hollow profile. The legs 74 can be fixed to the first flange 68 and / or the column bracket 22.

[0080] As shown in Figure 4, two adjacent columns 20 can be fixed to one column bracket 22 such that their respective case sheet members 52 are in contact with each other, preferably at the bottom of their respective channels 64.

[0081] Referring to Figure 5, the upper frame 24 is aligned with the bottom frame 20 so that the column 20 is vertical in the installed state. Therefore, for the sake of brevity, the configuration of the upper frame 24 will not be described again. Note that the same reference numbers are used as for the bottom frame, but with an apostrophe added. The upper frame 24 may be composed of separate metal profiles or bent sheet metal bolted together, or it may be formed integrally by welding bent sheet metal or metal profiles.

[0082] Referring to Figure 7, the column 20 may be integrally formed as a hollow profile of a single member with a rectangular cross-section.

[0083] Referring to Figure 8, column 20 may include reinforcing material placed within a hollow profile.

[0084] The applicant discovered through FEM simulation that the aforementioned frame structure 12 satisfies the vibration requirements defined by the aforementioned standards.

[0085] Referring to Figure 9, another form of the energy storage rack 10 is described in terms of differences from the previously described embodiment. The energy storage rack 10 comprises a plurality of structural braces 78. The structural braces 78 are located on the side 80 of the energy storage rack 10. Each structural brace 78 spans at least two columns 22 (front and rear). The structural braces 78 are made of bent sheet metal.

[0086] The energy storage rack 10 is equipped with multiple busbars 18, which are located at the front and electrically connect the energy storage modules 14. The busbars 18 are preferably supported by pillars 80 attached to a single column 22.

[0087] The energy storage rack 10 further includes at least one installation location 82. The installation location 82 is located below the bottom frame 20. The installation location 82 may be formed of sheet metal. Each installation location 82 may include an auxiliary power module 84 and / or a rack control unit 86. The auxiliary power module 84 is configured to supply power to the controllers of the energy storage rack 10 (module controller unit and rack control unit 86) in the event of a mains power failure. The rack control unit 86 is configured to control the module controller unit to form a manageable system.

[0088] The installation position 82 is located within the volume below the lower surface of the bottom frame 20 and between the high-voltage insulators 38.

[0089] As shown in Figure 10, a graph of spectral acceleration is displayed. The x-axis represents frequency, and the y-axis is approximately 9.8 m / s². 2 The acceleration is shown as a multiple of the Earth's acceleration. The line shows a frequency sweep using a sine wave and its amplitude. Data point ITER-1 shows, for comparison, the results for an energy storage rack with 20 modules and no integrated bottom frame. This does not meet seismic standards. Data point ITER-3 shows a significant improvement in the seismic behavior of the energy storage rack 10 with an integrated bottom frame 20 and four high-voltage insulators 38. Data point ITER-5 shows a further improvement in the seismic behavior of the energy storage rack 10 with an integrated bottom frame 20 and six high-voltage insulators 38.

[0090] In some embodiments, the mechanical rack consists of multiple energy storage modules. These modules may consist of supercapacitors or hybrid battery cells. In some embodiments, the vibration profile of the proposed rack is less than 33 Hz. Thus, the rack design complies with the seismic requirements for moderate seismic inputs of IEEE 693:2018 with 2% damping. In some embodiments, the rack has a welded beam base frame. In some embodiments, there are diagonal (angled) supports on the rear and both sides of the rack, and no supports on the front. In some embodiments, the height of the rack is minimized by moving all auxiliary equipment to the sides and / or under the framework. In some embodiments, there are no single-purpose steel components, and ideally all components contribute to strengthening the overall structure. In one embodiment, the rack is mounted on multiple, for example, six high-voltage insulators. One is located at each corner of the rack, and two are located under the center of a double rack. In one embodiment, the proposed rack includes a passive cooling mechanism that evenly distributes heat, preventing localized overheating and ensuring the reliability and lifespan of electronic components within the electrical energy storage system (ESS). In one embodiment, the temperature distribution has a constant gradient across the entire rack. The energy storage rack is earthquake-resistant and generally conforms to the IEEE 693:2018 seismic profile standard. In addition to its seismic design, the rack has a natural cooling function and preferably does not have an enclosure.

[0091] This rack is capable of preventing earthquake damage and is particularly suitable for high-voltage direct current (HVDC) systems, especially static synchronous compensators (STATCOM) or enhanced STATCOM (ESTACOM) systems. A single rack unit is preferably configured as a double rack containing multiple, for example, 10 to 20 energy storage modules, a master (module) controller, a bypass subassembly, an auxiliary ("aux.") power supply, and / or rack control equipment.

[0092] The rack unit framework dimensions are approximately 1200 x 600 x 2100 mm (width (W) x depth (D) x height (H), excluding insulation). ESS modules are designed to be mounted in racks with a typical 19-inch slider spacing. This is generally the main constraint determining the overall rack dimensions. The framework is preferably designed to accommodate 20 ESS modules. Modules are mounted on sliding brackets and are typically secured with screws from the front. The framework consists of two main subassemblies: a welded base frame and a sheet metal framework. Preferably, it is an open rack without walls. Racks are generally limited to an IP00 protective rating, which means a level of protection without special protection against solids or liquids.

[0093] The rack concept is extremely compact, with virtually no additional or arbitrary empty space that is not filled with the necessary equipment. To better conform to the seismic profile, the rack height is ideally kept to a minimum. Additionally or alternatively, all auxiliary equipment is installed on the sides and / or bottom of the rack. Minimizing the rack height also allows for improvements to potential logistical challenges such as transport limitations and maintainability (e.g., a reduction in the number of pieces of equipment reachable by a mobile platform). The rack is preferably installed on six high-voltage insulators, one at each corner of the rack and two under the middle section of a double rack. The auxiliary power system and rack control device are preferably installed under the rack base frame between the HV insulators. The applicant found, based on FEM analysis, that this installation location is optimal from an earthquake perspective.

[0094] The master controller generally plays the role of balancing the voltage of the cells in the rack. It can be installed at the top or bottom of the rack, preferably in a slotted mounting position. It is preferable to install the master controller at the top. In a dual-wire system, it is preferable to place the auxiliary power unit at the bottom of the rack from the viewpoint of seismic design and stability. It is preferable to place the grounding point used during maintenance in the center of the base frame.

[0095] In seismic design, it is preferable to improve stability by placing auxiliary units below the system's center of gravity. This improves stability and seismic resistance.

[0096] Generally, E-STATCOM systems are designed to withstand a moderate seismic profile as defined by IEEE 693:2018.

[0097] A series of preliminary seismic-specific simulations were conducted to design a rack that conforms to the standard. Following standard testing, two simulation targets were set. The first target was that the lowest horizontal natural frequency exceed 33 Hz. A design is still acceptable even if the vertical natural frequency is below 33 Hz. The natural frequencies must conform to the requirements of IEEE 693-2018; otherwise, vibration loads will be amplified, potentially leading to destructive resonances.

[0098] The second objective is to ensure that no failures are observed in the rack with respect to the provided vibration profile. The vibration profile is located below 33 Hz. Resonances below 33 Hz generally amplify seismic inputs. The simulation results show that the rack design meets the seismic requirements for moderate seismic inputs in IEEE 693:2018 with a 2% damping. No damage is observed in sinusoidal sweep fatigue calculations.

[0099] The best-performing design iteration of the Rack framework includes one of the following characteristics:

[0100] • Integrated (e.g., welded) beam base frame. • Diagonal supports on the back and / or sides of the framework. • At least four, preferably six, HV insulators. • The rack height is minimized by moving most or all of the auxiliary equipment to the sides and / or bottom of the frame. • Every component contributes to strengthening the overall structure. Furthermore, simulations revealed a suitable thermal management design.

[0101] The results are shown in Figures 11 to 13. The primary objective of the thermal simulation was to evaluate the effectiveness of the cooling concept for the E-STATCOM (double) rack design. Efficient thermal management is crucial for ensuring the reliability and lifespan of electronic components within the ESS. The simulation results showed that a passive cooling method is sufficient. A simplified rack model was used in the simulation to reduce simulation time.

[0102] The purpose of the simulation is to investigate the feasibility of the passive cooling concept in question. The analysis conditions are as follows:

[0103] • A simplified double-rack model for simulation. • Number of modules: 20 ESS modules. • To account for the worst-case scenario of airflow limitations, the Master Controller and Switchgear casings are included (on top). • Load: ESS module only - 31 Arms. • Module balancer temperature: 85℃ • Module power loss: 16.49W (cells and busbars only, excluding balancer) • The module is under end-of-life (EoL) conditions, ESR (200% of rated 1-second ESR) (equivalent series resistance) • Total power loss of the rack: 15.4 × 20 = 308W (cells and busbars only, excluding balancers) Ambient temperature: 26℃ • Cooling method: Natural convection • Temperature standard: Use the highest cell temperature. • Rack IP class: IP00

[0104] As shown in Figures 11A and 11B, the thermal simulation results show the temperature distribution within the E-STATCOM double rack design under specified conditions. The temperature distribution within the double rack shows a constant gradient, with the highest temperature occurring near the top of the rack due to natural convection.

[0105] The maximum cell temperature observed was approximately 48°C, which is within the component's acceptable operating range. This indicates that the passive cooling concept is sufficient to manage the heat generated by the ESS module. The temperature in the simulation showed a relatively uniform distribution across the module, with no significantly high-temperature areas. This indicates that the passive cooling mechanism distributes heat evenly and prevents localized overheating. It should be noted that the initial temperature of the front of the ESS module's PCB (printed circuit board) is 85°C.

[0106] Figure 12 shows a detailed analysis of the individual modules, notably the third module from the top, which exhibits a higher temperature in the center than at the edges. This core-to-edge temperature gradient is typical for this configuration but is manageable within safe limits.

[0107] Life simulations conducted after thermal simulations demonstrate that the current cooling configuration in the E-STATCOM double-rack design is effective. This study generally focuses on evaluating temperature rise and thermal resistance (Rth) within the module.

[0108] The key findings of the thermal analysis regarding temperature rise, thermal resistance, and lifetime prediction are discussed. The maximum cell temperature observed during the simulation was approximately 48°C. This temperature is well within the allowable operating range of the component. The thermal simulation revealed that the highest thermal resistance (Rth) value was 1.34 K / W. This value indicates efficient heat dissipation, showing that the system effectively manages the thermal load generated from the module. The Rth value used in the lifetime simulation is selected based on the highest module temperature value. Based on the temperature rise and calculated thermal resistance, the expected lifetime of the system component at an ambient temperature of 26°C is approximately 20 years.

[0109] Figure 13 shows the temperature and Rth values ​​obtained from thermal simulations. Module 8 had the highest recorded maximum temperature and is used as the baseline for the lifetime simulation. The modules are numbered from the lowest to the highest in the rack (Module 1 - the bottom module in the rack, Module 10 - the top module in the rack).

[0110] In a double-rack design, accurate temperature monitoring helps ensure optimal module performance and lifespan. The placement of temperature sensors is strategically designed to obtain accurate thermal data from critical points within the system. The sensors are located on the printed circuit board (PCB), not on the monitored cells themselves.

[0111] As shown in Figure 14, each cell is numbered from 1 to 54 (different from the reference numeral), and temperature sensors 88 are placed in critical locations to monitor the thermal state. Specifically, temperature sensors 90 on the bottom and 92 on the top are used. CM sensor 94 is for measuring the current of the PCB busbar.

[0112] Considering the effective thermal management demonstrated in the simulations, the current configuration of the double-track design does not require additional cooling. The passive cooling method utilizing natural convection is considered sufficient to maintain a safe operating temperature, thereby ensuring the lifespan and availability of the electronic components.

[0113] The decision to use IP00 class enclosures is further justified by their cost-effectiveness, optimal cooling performance, reduced complexity, and the achievement of a 20-year lifespan. Using natural convection cooling instead of forced cooling or liquid cooling solutions avoids additional costs, weight, operational complexity, and potential environmental impacts. This also potentially leads to a reduction in failure rates by avoiding additional failure modes associated with the aforementioned cooling solutions. This approach enables a reliable, efficient, and sustainable thermal management solution for rack systems.

[0114] (Note) [1] A cubic frame structure configured to absorb and / or dampen seismic vibrations, wherein the frame structure is suitable for an energy storage rack in an energy storage system. - A bottom frame integrally formed as a single component, having multiple column brackets protruding vertically upward, and configured to align columns parallel to each other in the vertical direction, - A plurality of columns, wherein the columns are attached to the base frame via the column brackets, and each column is formed as a hollow profile, -Includes an upper frame attached to each column, The columns work together to provide a frame structure that offers multiple mounting positions configured for receiving and mounting energy storage modules.

[0115] [2] The frame structure according to [1], wherein the bottom frame is integrally formed by welding or casting multiple parts.

[0116] [3] The frame structure according to [1] or [2], wherein each column is attached to the bottom frame and / or top frame by a number of bolt fasteners.

[0117] [4] The frame structure according to any one of [1] to [3], wherein the upper frame is preferably formed by welding or casting multiple components together as a single unit.

[0118] [5] The frame structure according to any one of [1] to [4], wherein at least one column bracket has a first leg extending parallel to the short side of the bottom frame and a second leg extending parallel to the long side of the bottom frame, preferably substantially perpendicular to the first leg, and the first and second legs are in contact with and / or fixed to the respective column, preferably the case sheet member.

[0119] [6] The frame structure according to [5], wherein the column bracket is formed at the corner of the bottom frame.

[0120] [7] At least one column bracket is formed at the end of the bottom frame, and the column bracket includes a third leg that extends parallel to and at a distance from the first leg, The frame structure according to [5] or [6], wherein the two column members fixed to the column bracket are mutually connected to the first leg and the third leg and the respective case sheet members.

[0121] [8] A frame structure according to any one of [1] to [7], wherein at least one column includes a case sheet member and a cover sheet member that engage with and / or are fixed to form the column.

[0122] [9] The frame structure according to [8], wherein the case sheet member includes at least three legs bent in a U shape to form a channel side wall and a channel bottom, the cover sheet member has at least two legs bent in an L shape, the cover sheet member closes the channel to form the hollow profile, and optionally the case sheet member includes a flange portion that partially protrudes inward from one side wall and parallel to the channel bottom.

[0123]

[10] A frame structure according to any one of [1] to [9], wherein at least one column is formed as a single integrally molded member.

[0124]

[11] The frame structure according to

[10] , wherein the column includes a reinforcing portion that extends parallel to the short side of the column in a cross-sectional view.

[0125]

[12] A frame structure according to any one of [1] to

[11] , further comprising at least one truss member, the truss member being fixed to one end of one column and to the other end or center, and forming an acute angle with each of the columns.

[0126]

[13] A frame structure according to any one of [1] to

[12] , wherein a plurality of high-voltage insulators are preferably welded to the bottom frame.

[0127]

[14] The frame structure according to any one of [1] to

[13] , further comprising at least one installation location located below the bottom frame, preferably adjacent to the bottom frame, for receiving and installing an auxiliary power module for supplying auxiliary power in the event of a main power failure and / or a rack control unit for controlling the energy storage module.

[0128]

[15] An energy storage rack for an energy storage system, An energy storage rack comprising a frame structure as described in any of [1] to

[14] and a plurality of energy storage modules configured for the storage and supply of power, wherein the energy storage modules are mounted in the mounting positions provided by the frame structure.

[0129]

[16] The energy storage rack according to

[15] , wherein the energy storage module includes an energy storage device including a supercapacitor.

[0130]

[17] The energy storage rack according to

[15] or

[16] , wherein the frame structure is the frame structure of

[14] , and at least one auxiliary power module and / or at least one rack control unit is installed in the installation location.

[0131]

[18] The energy storage rack according to any one of

[15] to

[17] , wherein the energy storage module is passively cooled, preferably so that a constant temperature gradient is formed throughout the energy storage rack.

[0132]

[19] Each energy storage module comprises a plurality of energy storage cells arranged in a densely packed, uniform cylindrical or rectangular pattern of hexagons, as described in

[18] .

[0133]

[20] The energy storage rack according to

[18] or

[19] , wherein each energy storage module includes a heat sink located on the side facing outward, preferably the front or rear side of the energy storage module. [Explanation of Symbols]

[0134] 10 Energy Storage Racks 12-frame structure 14 Energy storage modules 16. Mounting position 18 Bus Bar 20 Bottom frame 22 columns 24 Upper frame 26 Truss 28 Front (bottom frame) 28' Front (Upper Frame) 30 Rear (bottom frame) 30' Rear (upper frame) 32 Side (bottom frame) 32' Side (Upper Frame) 34 Side (bottom frame) 34' Side (upper frame) 36 Cross beam (bottom frame) 36' Crossbeam (Upper Frame) 37 Stabilizer 38 High-voltage (HV) insulators 40 Corner section 42 Middle part 44 Column Brackets 46 First leg 48 Second leg 50 Third leg 52 Case sheet components 54 Cover sheet component 56 Legs 58 Legs 60 Legs 62 Side wall 64 Channel bottom 66 channels 68 First Flange 70 Second flange 72 Support Rails 74 Legs 76 Legs 78 Structural braces 80 pillars 82 Installation position 84 Auxiliary power module 86 Rack Control Unit 88 Temperature Sensor 90 Bottom temperature sensor 92 Top-side temperature sensor 94 CM sensor

Claims

1. A cubic frame structure configured to absorb and / or dampen seismic vibrations, wherein the frame structure is suitable for an energy storage rack in an energy storage system. - A bottom frame formed integrally as a single component, having multiple column brackets protruding vertically upward, and configured to align columns parallel to each other in the vertical direction, - A plurality of columns, each column being mounted to the base frame via the column bracket, and each column being formed as a hollow profile, - Includes an upper frame attached to each column, The columns work together to provide a frame structure that offers multiple mounting positions configured for receiving and mounting energy storage modules.

2. The frame structure according to claim 1, wherein the bottom frame is integrally formed by welding or casting multiple parts.

3. The frame structure according to claim 1 or 2, wherein each column is attached to the bottom frame and / or upper frame by a plurality of bolt fasteners.

4. The frame structure according to any one of claims 1 to 3, wherein the upper frame is preferably formed integrally as a single member by welding or casting a plurality of components.

5. The frame structure according to any one of claims 1 to 4, wherein at least one column bracket has a first leg extending parallel to the short side of the bottom frame and a second leg extending parallel to the long side of the bottom frame, preferably substantially perpendicular to the first leg, and the first leg and the second leg are in contact with and / or fixed to the respective column, preferably a case sheet member.

6. The frame structure according to claim 5, wherein the column bracket is formed at the corner of the bottom frame.

7. At least one column bracket is formed at the end of the bottom frame, and the column bracket includes a third leg that extends parallel to and at a distance from the first leg. The frame structure according to claim 5 or 6, wherein the two column members fixed to the column bracket are interconnected with the first leg and the third leg and the respective case sheet members.

8. The frame structure according to any one of claims 1 to 7, wherein at least one column includes a case sheet member and a cover sheet member that engage with and / or are fixed to form the column.

9. The frame structure according to claim 8, wherein the case sheet member includes at least three U-shaped bent legs to form a channel side wall and a channel bottom, the cover sheet member has at least two L-shaped bent legs, the cover sheet member closes the channel to form the hollow profile, and optionally the case sheet member includes a flange portion that partially protrudes inward from one side wall and parallel to the channel bottom.

10. The frame structure according to any one of claims 1 to 9, wherein at least one column is formed as a single integrally molded member.

11. The frame structure according to claim 10, wherein the column includes a reinforcing portion that extends parallel to the short side of the column in a cross-sectional view.

12. The frame structure according to any one of claims 1 to 11, further comprising at least one truss member, the truss member being fixed to one end of one column and to the other end or center, forming an acute angle with each of the columns.

13. The frame structure according to any one of claims 1 to 12, wherein a plurality of high-voltage insulators are preferably welded and fixed to the bottom frame.

14. The frame structure according to any one of claims 1 to 13, further comprising at least one installation location located below the bottom frame, preferably adjacent to the bottom frame, for receiving and installing an auxiliary power module for supplying auxiliary power in the event of a main power failure and / or a rack control unit for controlling the energy storage module.

15. An energy storage rack for an energy storage system, An energy storage rack comprising a frame structure according to any one of claims 1 to 14 and a plurality of energy storage modules configured for the storage and supply of power, wherein the energy storage modules are mounted at the mounting positions provided by the frame structure.

16. The energy storage rack according to claim 15, wherein the energy storage module includes an energy storage device including a supercapacitor.

17. The energy storage rack according to claim 15 or 16, wherein the frame structure is the frame structure of claim 14, and at least one auxiliary power module and / or at least one rack control unit is installed at the installation location.

18. The energy storage rack according to any one of claims 15 to 17, wherein the energy storage module is passively cooled, preferably so that a constant temperature gradient is formed throughout the entire energy storage rack.

19. The energy storage rack according to claim 18, wherein each energy storage module comprises a plurality of energy storage cells arranged in a densely packed, uniform cylindrical or rectangular hexagonal pattern.

20. The energy storage rack according to claim 18 or 19, wherein each energy storage module includes a heat sink disposed on the side facing outward, preferably the front or rear side of the energy storage module.

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