An energy storage system and an energy storage tank

Abstract

The embodiment of the application discloses a kind of energy storage system and energy storage box, it is related to energy storage technical field, it can be powered to the auxiliary equipment inside each energy storage box, and avoid reducing the reliability of energy storage system.The energy storage system includes box-type substation and multiple energy storage boxes.Each energy storage box includes energy storage converter, battery cluster, AC busbar, auxiliary power converter and auxiliary equipment, the AC busbar between multiple energy storage boxes is connected in series, the AC busbar of the energy storage box at the end on the series connection path of multiple energy storage boxes is used to output electric energy to the low-voltage interface of box-type substation, the box-type substation is used to step up the electric energy received by low-voltage interface, the energy storage converter is used to convert the electric energy of battery cluster and output to AC busbar, and the auxiliary power converter is used to take electricity from AC busbar to power the auxiliary equipment.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to an energy storage system and an energy storage box. Background Technology

[0002] The energy storage system includes a prefabricated substation, an auxiliary transformer, and multiple energy storage boxes. Each energy storage box includes a power conversion system (PCS), a battery cluster (BC), an AC busbar, and auxiliary equipment (AE). The PCS converts the power from the battery cluster and outputs it to the AC busbar. The AC buses of the multiple energy storage boxes are connected in series. The AC busbar of the last energy storage box in the series path is connected to the low-voltage interface of the prefabricated substation. This last energy storage box's AC busbar outputs power to the low-voltage interface of the prefabricated substation. The medium-voltage interface of the prefabricated substation is used to connect to the power grid. The prefabricated substation is used to boost the voltage of the power received at the low-voltage interface and transmit it to the power grid. The input of the auxiliary transformer is connected to the low-voltage interface of the prefabricated substation, and the output of the auxiliary transformer is connected to the auxiliary equipment inside each energy storage box.

[0003] Specifically, the output of the auxiliary transformer is connected to the auxiliary equipment inside each energy storage box via underground cables. The auxiliary transformer is used to transform the AC power from the low-voltage interface of the prefabricated substation to supply power to the auxiliary equipment inside each energy storage box.

[0004] However, during the actual construction of the aforementioned system architecture, wiring, trenching, and connection work are required between the auxiliary transformers and the auxiliary equipment inside each energy storage tank. This results in a long construction period and high operational difficulty. Furthermore, the harsh on-site environment and the non-standard manual wiring work can easily lead to wiring problems, thereby reducing the reliability of the energy storage system. Therefore, how to supply power to the auxiliary equipment inside each energy storage tank without compromising the reliability of the energy storage system has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides an energy storage system and an energy storage box, which solves the problem of how to supply power to the auxiliary equipment inside each energy storage box and avoid reducing the reliability of the energy storage system.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions: A first aspect of this application provides an energy storage system comprising a prefabricated substation and multiple energy storage boxes. Each energy storage box includes an energy storage converter, a battery cluster, an AC busbar, an auxiliary power converter, and auxiliary equipment. The AC busbars of the multiple energy storage boxes are connected in series. The AC busbar of the energy storage box at the end of the series path is connected to the low-voltage interface of the prefabricated substation. The AC busbar of the energy storage box at the end is used to output electrical energy to the low-voltage interface of the prefabricated substation. The prefabricated substation is used to boost the electrical energy received at the low-voltage interface. The energy storage converter is used to convert the electrical energy from the battery cluster into power and output it to the AC busbar. The auxiliary power converter is used to draw power from the AC busbar to supply power to the auxiliary equipment.

[0007] In one embodiment, the auxiliary equipment includes a liquid cooling unit, a fire suppression system, lighting equipment, or monitoring equipment. Powering critical auxiliary equipment in the energy storage tank via the aforementioned auxiliary power converter improves the safety and reliability of the energy storage tank, thereby enhancing the reliability of the energy storage system.

[0008] In one embodiment, the auxiliary power converter includes a transformer, an alternating current to direct current (AC-DC) converter, an AC-DC and direct current to alternating current (DC-AC) combined converter, or a solid-state transformer. A state transformer (SST) is used to convert alternating current (AC) with one parameter to AC with another parameter. The auxiliary power converter is an AC-to-AC (alternating current to alternating current) power converter, or it is used to convert AC to DC (AC-DC) power converter. This application does not limit the specific type of auxiliary power converter. The auxiliary power converter can be flexibly selected as needed to adapt to the power supply requirements of different auxiliary devices.

[0009] Currently, auxiliary transformers are independently externally mounted in the energy storage boxes, connected to the auxiliary equipment inside each box via buried cables. The auxiliary transformers transform the AC power from the low-voltage interface of the prefabricated substation to supply power to the auxiliary equipment within each box. Firstly, during actual construction, the connection between the auxiliary transformers and the auxiliary equipment in each box requires wiring, trenching, and connection work, leading to a long construction period and high operational difficulty. Secondly, the independent external mounting of the auxiliary transformers necessitates on-site wiring, which is susceptible to poor wiring due to harsh on-site environments and non-standardized manual wiring, thus reducing the reliability of the energy storage system.

[0010] Based on this solution, each energy storage box incorporates a built-in auxiliary power converter. This converter transforms the AC power in the AC busbar to supply power to auxiliary equipment. During actual construction, no wiring, trenching, or connection work is required between the auxiliary power converter and the auxiliary equipment, which helps shorten the construction cycle and reduce operational difficulty. Secondly, since the auxiliary power converter is built into the energy storage box, the wiring between the converter and the auxiliary equipment is already completed before the energy storage box leaves the factory. This eliminates the need for on-site wiring work, is unaffected by harsh on-site environments or non-standard manual wiring, avoids wiring problems, and thus improves the reliability of the energy storage system.

[0011] In conjunction with the first aspect, in one embodiment, multiple energy storage boxes are arranged at intervals along the length of the energy storage boxes. Each energy storage box and an adjacent energy storage box has an opening on its opposite sidewall. An AC busbar inside the energy storage box extends along the length of the energy storage box, and one end of the AC busbar of the energy storage box is connected in series with one end of the AC busbar of an adjacent energy storage box through the opening.

[0012] Based on this scheme, multiple energy storage boxes are arranged at intervals along the length direction, and the AC busbars in each energy storage box are connected in series by a handle, which can reduce the amount of AC busbars used, simplify the wiring structure, and make the system flexible and scalable.

[0013] In conjunction with the first aspect, in one implementation, the medium-voltage interface of the prefabricated substation is used to connect to the power grid. The prefabricated substation is used to convert the AC power supplied by the power grid to a voltage level greater than or equal to a voltage threshold, and then output electrical energy to the AC busbar.

[0014] Based on this scheme, when the grid is energized, the auxiliary power converter draws power from the grid through the AC busbar and the prefabricated substation to supply power to the auxiliary equipment. The auxiliary power converter does not need to draw power from the battery clusters to supply power to the auxiliary equipment through the AC busbar and energy storage converter in the energy storage box. This helps to reduce equipment losses of the energy storage converter and battery clusters in the energy storage box, extend the service life of the equipment, and reserve the power of the battery clusters for emergency use, which helps to improve the stability of the energy storage system.

[0015] In conjunction with the first aspect, in one embodiment, the battery clusters of the energy storage box are used to discharge to the AC busbar of the energy storage box when the state of charge (SOC) of the energy storage box is greater than or equal to the SOC threshold, so that the auxiliary power converter in the energy storage box draws power from the AC busbar.

[0016] Based on this scheme, when the energy storage box has sufficient power, the battery clusters in the energy storage box discharge to the AC bus through the energy storage converter. The auxiliary power converter draws power from the AC bus and performs power conversion to supply power to the auxiliary equipment, thereby improving the reliability of power supply to the auxiliary equipment.

[0017] In conjunction with the first aspect, in one embodiment, the plurality of energy storage boxes include a first energy storage box and a second energy storage box, with one end of the AC busbar of the first energy storage box connected in series with one end of the AC busbar of the second energy storage box. The second energy storage box is used to discharge the battery clusters in the second energy storage box to the AC busbar of the second energy storage box when the SOC of the battery clusters in the first energy storage box is lower than the SOC of the battery clusters in the second energy storage box, so that the auxiliary power converter in the first energy storage box draws power from the AC busbar of the first energy storage box.

[0018] Based on this scheme, when the battery clusters in the first energy storage box have insufficient power but the battery clusters in the second energy storage box have sufficient power, the energy storage converter in the second energy storage box converts the DC power provided by the battery clusters in the second energy storage box into AC power to supply AC power to the AC bus in the second energy storage box. The auxiliary power converter in the first energy storage box draws power from the AC bus in the first energy storage box and performs power conversion on the AC power to supply power to the auxiliary equipment in the first energy storage box, thereby further improving the reliability of power supply to the auxiliary equipment in the first energy storage box.

[0019] In conjunction with the first aspect, in one embodiment, each energy storage box further includes a controller. The controller is used to control the power reduction of the energy storage converter when the sum of the AC terminal current of the energy storage converter and the input terminal current of the auxiliary power converter is greater than or equal to a first current threshold.

[0020] Based on this scheme, when the current in the AC busbar exceeds the current limit, it is easy to cause an overcurrent fault, which may lead to safety hazards such as line overheating and device damage. Therefore, when the sum of the AC terminal current of the energy storage converter and the input terminal current of the auxiliary power converter is greater than or equal to the first current threshold, the controller controls the energy storage converter to operate at a reduced rate, thereby avoiding the occurrence of an overcurrent fault. At the same time, without controlling the auxiliary power converter to operate at a reduced rate, the power supply needs of the auxiliary equipment can still be met.

[0021] In conjunction with the first aspect, in one embodiment, the energy storage system further includes a system controller. The system controller is used to control a reduction in the power of the energy storage converter in each energy storage box connected to the low-voltage interface of the prefabricated substation when the current at the low-voltage interface of the prefabricated substation is greater than or equal to a second current threshold.

[0022] Based on this scheme, as mentioned above, when the current in the AC busbar is too large, it is easy to cause an overcurrent fault. Therefore, when the low-voltage interface current of the prefabricated substation is greater than or equal to the second current threshold, the system controller controls the energy storage converter in each energy storage box connected to the low-voltage interface of the prefabricated substation to operate at a reduced rate, thereby avoiding the occurrence of an overcurrent fault. At the same time, the auxiliary power converter in each energy storage box is not controlled to operate at a reduced rate, so that the power supply needs of the auxiliary equipment can continue to be met.

[0023] In conjunction with the first aspect, in one embodiment, each energy storage box further includes a switch, through which an auxiliary power converter is connected to an AC bus, or the auxiliary power converter is connected to the AC bus via a plug-in method.

[0024] Based on this solution, the auxiliary power converter is connected to the AC busbar via a switch. Disconnecting the auxiliary power converter from the AC busbar can be achieved by disconnecting the switch, facilitating fault isolation, flexible switching, and equipment protection. The auxiliary power converter uses a quick-plug connection to the AC busbar, enabling rapid disassembly and maintenance, flexible equipment deployment, simplified wiring procedures, and improved operation and maintenance efficiency and ease of use.

[0025] In conjunction with the first aspect, in one embodiment, multiple energy storage boxes connected in series constitute a group of energy storage boxes, and the energy storage system includes at least two groups of energy storage boxes. The low-voltage interface of the prefabricated substation includes at least two groups of low-voltage interfaces, and the AC busbar of the energy storage box at the end of the series path of each of the at least two groups of energy storage boxes is connected one-to-one with the low-voltage interface of the at least two groups of prefabricated substations.

[0026] Based on this scheme, by adopting the above connection method, the DC and AC circulating currents between the energy storage boxes connected to the low-voltage interfaces of at least two sets of prefabricated substations can be blocked, reducing losses and heat generation, and preventing fault propagation. In addition, the energy storage boxes connected to the low-voltage interfaces of at least two sets of prefabricated substations can be independently scheduled and put into operation or decommissioned in stages, improving the reliability and operational flexibility of the energy storage system.

[0027] A second aspect of this application provides an energy storage box, which includes an energy storage converter, a battery cluster, an auxiliary power converter, an AC busbar, and auxiliary equipment. The energy storage converter converts the electrical energy from the battery cluster into power and outputs it to the AC busbar. The auxiliary power converter draws power from the AC busbar to power the auxiliary equipment. The AC busbar of the energy storage box outputs electrical energy to the low-voltage interface of a prefabricated substation, which then boosts the voltage of the electrical energy received at the low-voltage interface.

[0028] In conjunction with the second aspect, in one embodiment, the energy storage box includes multiple energy storage converters and multiple battery clusters, with each of the multiple energy storage converters and multiple battery clusters being electrically connected in a one-to-one correspondence. The multiple energy storage converters are arranged along the length of the energy storage box, and the AC busbar extends along the length of the energy storage box.

[0029] The description of the second aspect in this application can be referred to the detailed description of the first aspect; and the beneficial effects of the second aspect can be referred to the analysis of the beneficial effects of the first aspect, which will not be repeated here. Attached Figure Description

[0030] Figure 1 A circuit topology diagram of an energy storage system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application; Figure 3 A schematic diagram of another energy storage system provided in this application embodiment; Figure 4 This is a schematic diagram of another energy storage system provided in an embodiment of this application; Figure 5 A circuit topology diagram of another energy storage system provided in the embodiments of this application; Figure 6 A circuit topology diagram of another energy storage system provided in an embodiment of this application. Detailed Implementation

[0031] The following sections will discuss the fabrication and use of various embodiments in detail. However, it should be understood that many applicable inventive concepts provided in this application can be implemented in a variety of specific environments. The specific embodiments discussed are merely illustrative of specific ways of implementing and using this description and technology, and do not limit the scope of this application.

[0032] Unless otherwise defined, all technical terms used herein have the same meaning as commonly known to one of ordinary skill in the art.

[0033] Each circuit or other component may be described or referred to as "for" performing one or more tasks. In this context, "for" is used to imply a structure by indicating that the circuit / component includes a structure (e.g., a circuit system) that performs one or more tasks during operation. Therefore, even when the specified circuit / component is currently inoperable (e.g., not turned on), it can still be referred to as "for performing that task." Circuits / components used with the term "for" include hardware, such as circuits that perform operations.

[0034] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. In this application, "multiple" refers to two or more. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. In addition, in the embodiments of this application, the words "first," "second," etc., do not limit the quantity or order.

[0035] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0036] Before introducing the embodiments of this application, the background technology involved in this application will be introduced first.

[0037] like Figure 1The diagram shows a circuit topology of an energy storage system 100 according to an embodiment of this application. The energy storage system 100 includes a prefabricated substation 110, an auxiliary transformer 120, and multiple energy storage boxes (131 and 132). For each energy storage box, taking energy storage box 131 as an example, energy storage box 131 includes an energy storage converter PCS, a battery cluster BC, an AC bus 1311, and auxiliary equipment AE. The energy storage converter PCS is used to convert the electrical energy of the battery cluster BC into power and output it to the AC bus 1311. Multiple energy storage boxes (131 and 132) have their AC busbars (1311 and 1321) connected in series. The AC busbar 1321 of the energy storage box 132, located at the end of the series path, is connected to the low-voltage interface of the prefabricated substation 110. This AC busbar 1321 of the end energy storage box 132 is used to output electrical energy to the low-voltage interface of the prefabricated substation 110. The medium-voltage interface of the prefabricated substation 110 is used to connect to the power grid 200. The prefabricated substation 110 is used to boost the electrical energy received at the low-voltage interface and transmit it to the power grid 200. The input terminal of the auxiliary transformer 120 is connected to the low-voltage interface of the prefabricated substation 110, and the output terminal of the auxiliary transformer 120 is connected to the auxiliary equipment AE inside each energy storage box. The auxiliary equipment AE includes liquid cooling units, fire protection systems, lighting equipment, or monitoring equipment.

[0038] In one implementation, continue to refer to Figure 1 Each energy storage box includes multiple energy storage converters (PCS) and multiple battery clusters (BC), and the multiple energy storage converters (PCS) and multiple battery clusters (BC) in the energy storage box are electrically connected one-to-one.

[0039] In one implementation, reference Figure 1 Multiple energy storage boxes connected in series form a group of energy storage boxes. The energy storage system 100 includes at least two groups of energy storage boxes. For example, the energy storage system 100 includes two groups of energy storage boxes. Energy storage boxes 131 and 132 form one group of energy storage boxes, and energy storage boxes 133 and 134 form another group of energy storage boxes. The low-voltage interface of the prefabricated substation 110 includes at least two sets of low-voltage interfaces. For example, the transformer T in the prefabricated substation 110 is a low-voltage double-split three-winding transformer. The transformer T includes one medium-voltage winding and two low-voltage windings coupled to the one medium-voltage winding. The low-voltage interface of the prefabricated substation 110 includes two sets of low-voltage interfaces. The energy storage box 132 is the energy storage box located at the end of the series path of one set of energy storage boxes. The AC busbar 1321 of the energy storage box 132 is connected to the low-voltage interface of one set of prefabricated substation 110. The energy storage box 133 is the energy storage box located at the end of the series path of another set of energy storage boxes. The AC busbar 1331 of the energy storage box 133 is connected to the low-voltage interface of another set of prefabricated substation 110.

[0040] In one implementation, continue to refer to Figure 1The energy storage system 100 may also include two sets of energy storage boxes. Energy storage boxes 135 and 136 form one set of energy storage boxes, and energy storage boxes 137 and 138 form the other set of energy storage boxes. The specific connection relationship is as follows: Figure 1 The embodiments of this application will not be described in detail here.

[0041] In one implementation, continue to refer to Figure 1 The energy storage system 100 may include two auxiliary transformers (120 and 140). The input terminals of the two auxiliary transformers (120 and 140) are respectively connected to two sets of low-voltage interfaces of the prefabricated substation 110, and the output terminals of the two auxiliary transformers (120 and 140) are respectively connected to the auxiliary equipment AE inside each energy storage box. The specific connection relationship is as follows. Figure 1 The embodiments of this application will not be described in detail here.

[0042] Specifically, such as Figure 2 The diagram shows a structural schematic of an energy storage system 100 provided in an embodiment of this application. The output terminals of the auxiliary transformers (120 and 140) are connected to the auxiliary equipment AE inside each energy storage box via buried cables. The auxiliary transformers (120 and 140) are used to transform the AC power from the low-voltage interface of the prefabricated substation 110 to supply power to the auxiliary equipment AE inside each energy storage box. Buried cables refer to cables laid underground.

[0043] However, refer to Figure 2 During the actual construction of the aforementioned system architecture, wiring, trenching, and connection work are required between the auxiliary transformers (120 and 140) and the auxiliary equipment (AE) inside each energy storage box. This results in a long construction period and high operational difficulty. Furthermore, the harsh on-site environment and non-standard manual wiring can easily lead to wiring defects, thereby reducing the reliability of the energy storage system 100. Therefore, how to supply power to the auxiliary equipment (AE) inside each energy storage box without reducing the reliability of the energy storage system 100 has become an urgent technical problem to be solved.

[0044] Based on this, this application provides an energy storage system in which each energy storage box has a built-in auxiliary power converter. The auxiliary power converter is used to convert the AC power in the AC busbar to supply power to auxiliary equipment. In actual construction, there is no need to do wiring, trenching, or connection work between the auxiliary power converter and the auxiliary equipment, and there is no need to do on-site wiring work. This helps to shorten the construction cycle, reduce the difficulty of operation, and improve the reliability of the energy storage system.

[0045] like Figure 3 The diagram shown is a circuit topology diagram of an energy storage system 300 provided in an embodiment of this application. Figure 4The diagram shown is a structural schematic of an energy storage system 300 provided in an embodiment of this application. The energy storage system 300 includes a prefabricated substation 310 and multiple energy storage boxes (321 and 322). This embodiment of the application does not limit the specific number of the multiple energy storage boxes.

[0046] For each energy storage box, taking energy storage box 321 as an example, energy storage box 321 includes an energy storage converter PCS, a battery cluster BC, an AC busbar 3211, an auxiliary power converter (APC), and auxiliary equipment AE. The AC buses (3211 and 3221) of multiple energy storage boxes (321 and 322) are connected in series. The AC busbar 3221 of the energy storage box 322, which is located at the end of the series path of multiple energy storage boxes (321 and 322), is connected to the low-voltage interface of the prefabricated substation 310. The AC busbar 3221 of the energy storage box 322 at the end is used to output electrical energy to the low-voltage interface of the prefabricated substation 310, and the prefabricated substation 310 is used to boost the electrical energy received by the low-voltage interface. For each energy storage box, taking energy storage box 321 as an example, the energy storage converter PCS is used to convert the electrical energy of the battery cluster BC into power and output it to the AC bus 3211. The auxiliary power converter APC is used to draw power from the AC bus 3211 to supply power to the auxiliary equipment AE.

[0047] The AC busbar 3221 of the energy storage box 322 located at the end is used to output electrical energy to the low-voltage interface of the prefabricated substation 310. This means that the battery cluster BC in the energy storage box 321 discharges to the AC busbar 3211 through the energy storage converter PCS and transmits the energy to the AC busbar 3221. The battery cluster BC in the energy storage box 322 discharges to the AC busbar 3221 through the energy storage converter PCS. The AC busbar 3221 outputs electrical energy to the low-voltage interface of the prefabricated substation 310.

[0048] In one embodiment, the aforementioned auxiliary power converter (APC) includes a transformer, an AC-DC converter, an AC-DC and DC-AC combined converter, or a solid-state transformer (SST). The APC can be used to convert AC power of one parameter to AC power of another parameter; the APC is an AC-AC power converter. Alternatively, the APC can be used to convert AC power to DC power; the APC is an AC-DC power converter. This application does not limit the specific type of APC. The APC can flexibly select specific power converters as needed, thereby flexibly adapting to the power supply requirements of different auxiliary equipment (AEs). This application does not limit the specific type of APC.

[0049] In one embodiment, the auxiliary equipment AE includes a liquid cooling unit, a fire protection system, lighting equipment, or monitoring equipment. Continuing with the energy storage box 321 as an example, supplying power to the critical auxiliary equipment AE in the energy storage box 321 through the aforementioned auxiliary power converter APC helps improve the safety and reliability of the energy storage box 321, thereby improving the reliability of the energy storage system 300.

[0050] In one implementation, reference Figure 3 and Figure 4 For each energy storage box, taking energy storage box 321 as an example, energy storage box 321 includes multiple energy storage converters PCS and multiple battery clusters BC. The multiple energy storage converters PCS and multiple battery clusters BC included in energy storage box 321 are electrically connected in a one-to-one correspondence. The multiple energy storage converters PCS are arranged along the length direction of energy storage box BC, and AC busbar 3211 extends along the length direction of energy storage.

[0051] In one implementation, reference Figure 4 Multiple energy storage boxes (321 and 322) are arranged at intervals along the length of the energy storage box. Each energy storage box 321 and its adjacent counterpart has an opening on its sidewall. AC busbars (3211 and 3221) within the energy storage boxes (321 and 322) extend along the length of the energy storage box. One end of the AC busbar 3211 of energy storage box 321 is connected in series with one end of the AC busbar 3221 of the adjacent energy storage box 322 through an opening. The arrangement of multiple energy storage boxes (321 and 322) at intervals along the length, with the AC busbars within each box connected in series, reduces the number of AC busbars required, simplifies the wiring structure, and allows for flexible system expansion and excellent scalability.

[0052] The above Figure 1 and Figure 2 In the energy storage system 100, auxiliary transformers (120 and 140) are independently externally mounted in the energy storage box and connected to the auxiliary equipment AE inside each energy storage box via buried cables. The auxiliary transformers (120 and 140) are used to transform the AC power from the low-voltage interface of the prefabricated substation 110 to supply power to the auxiliary equipment AE inside each energy storage box. Firstly, during actual construction of the energy storage system 100, wiring, trenching, and connection work are required between the auxiliary transformers (120 and 140) and the auxiliary equipment AE inside each energy storage box, resulting in a long construction period and high operational difficulty. Secondly, the independent external mounting of the auxiliary transformers (120 and 140) and the connection between them and the auxiliary equipment AE requires on-site work. Due to the harsh on-site environment and the non-standard manual wiring work, poor wiring problems are prone to occur, thus reducing the reliability of the energy storage system 100.

[0053] The energy storage system 100 provided in this application embodiment, taking energy storage box 321 as an example, has an auxiliary power converter (APC) built into each energy storage box 321. The APC converts the AC power in the AC busbar 3211 to supply power to auxiliary equipment AE. During actual construction, no wiring, trenching, or connection work is required between the APC and AE, which helps shorten the construction cycle and reduce operational difficulty. Secondly, since the APC is built into the energy storage box, the wiring between the APC and AE is completed before the energy storage box leaves the factory, eliminating the need for on-site wiring work. This avoids the impact of harsh on-site environments and non-standard manual wiring, preventing wiring problems and thus improving the reliability of the energy storage system 300.

[0054] In one implementation, continue to refer to Figure 3 and Figure 4 Taking the energy storage box 321 as an example, the medium-voltage interface of the prefabricated substation 310 is used to connect to the power grid 200. When the voltage of the power grid 200 is greater than or equal to a voltage threshold, the prefabricated substation 310 performs voltage conversion on the AC power supplied by the power grid 200 and outputs electrical energy to the AC busbar 3211. The auxiliary power converter (APC) in the energy storage box 321 performs power conversion on the AC power supplied by the prefabricated substation 310 to the AC busbar 3211 to supply power to the auxiliary equipment AE. This embodiment does not limit the specific value of the voltage threshold.

[0055] The energy storage system 300 provided in this application embodiment, when the power grid 200 is energized, the auxiliary power converter APC draws power from the power grid 200 through the AC bus 3211 and the box-type substation 310 to supply power to the auxiliary equipment AE. The auxiliary power converter APC does not need to draw power from the battery cluster BC to supply power to the auxiliary equipment AE through the AC bus 3211 and the energy storage converter PCS in the energy storage box 321. This helps to reduce the equipment losses of the energy storage converter PCS and the battery cluster BC in the energy storage box 321, extend the service life of the equipment, and reserve the power of the battery cluster BC for emergency use, which helps to improve the stability of the energy storage system 300.

[0056] In one implementation, continue to refer to Figure 3 and Figure 4 Taking the energy storage box 321 as an example, the battery cluster BC of the energy storage box 321 is used to discharge to the AC bus 3211 of the energy storage box 321 through the energy storage converter PCS when the state of charge (SOC) of the energy storage box 321 is greater than or equal to the SOC threshold, so that the auxiliary power converter APC in the energy storage box 321 draws power from the AC bus 3211 to supply power to the auxiliary equipment AE. The specific value of the SOC threshold is not limited in the embodiments of this application.

[0057] In one embodiment, when the power grid 200 is de-energized and the above conditions are met, the battery cluster BC discharges through the energy storage converter PCS to the AC bus 3211 of the energy storage box 321, so that the auxiliary power converter APC in the energy storage box 321 draws power from the AC bus 3211 to supply power to the auxiliary equipment AE.

[0058] The energy storage system 300 provided in this application embodiment, when the energy storage box 321 has sufficient power, the battery cluster BC in the energy storage box 321 is discharged to the AC bus 3211 through the energy storage converter PCS. The auxiliary power converter APC draws power from the AC bus 3211 and performs power conversion to supply power to the auxiliary equipment AE, thereby improving the reliability of power supply to the auxiliary equipment AE.

[0059] In one embodiment, the plurality of energy storage boxes (321 and 322) includes a first energy storage box 321 and a second energy storage box 322. One end of the AC bus 3211 of the first energy storage box 321 is connected in series with one end of the AC bus 3221 of the second energy storage box 322. The second energy storage box 322 is used to discharge the battery cluster BC in the second energy storage box 322 to the AC bus 3221 of the second energy storage box 322 when the SOC of the battery cluster BC in the first energy storage box 321 is less than the SOC of the battery cluster BC in the second energy storage box 322. This allows the auxiliary power converter APC in the first energy storage box 321 to draw power from the AC bus 3211 of the first energy storage box 321 and supply power to the auxiliary equipment AE in the first energy storage box 321.

[0060] In one embodiment, when the power grid 200 is de-energized and the above conditions are met, the battery cluster BC in the second energy storage box 322 discharges to the AC bus 3221 of the second energy storage box 322, so that the auxiliary power converter APC in the first energy storage box 321 draws power from the AC bus 3211 of the first energy storage box 321 to supply power to the auxiliary equipment AE in the first energy storage box 321.

[0061] The energy storage system 300 provided in this application embodiment, when the battery cluster BC in the first energy storage box 321 has insufficient power and the battery cluster BC in the second energy storage box 322 has sufficient power, the energy storage converter PCS in the second energy storage box 322 converts the DC power provided by the battery cluster BC in the second energy storage box 322 into AC power to provide AC power to the AC bus 3221 in the second energy storage box 322. The auxiliary power converter APC in the first energy storage box 321 draws power from the AC bus 3211 in the first energy storage box 321 and performs power conversion on the AC power to supply power to the auxiliary equipment AE in the first energy storage box 321, thereby further improving the reliability of power supply to the auxiliary equipment AE in the first energy storage box 321.

[0062] In one implementation, each energy storage box also includes a controller. For example... Figure 5 The diagram shown is a circuit topology diagram of another energy storage system 300 provided in the embodiment of this application. Taking the energy storage box 321 as an example, the energy storage box 321 also includes a controller 3212.

[0063] The controller 3212 is used to control the power of the energy storage converter PCS to decrease when the sum of the AC terminal current of the energy storage converter PCS and the input terminal current of the auxiliary power converter APC in the energy storage box 321 is greater than or equal to a first current threshold I1. The specific value of the first current threshold I1 is not limited in this embodiment.

[0064] In one embodiment, the controller 3212 controls the power reduction of the energy storage converter PCS, including: the controller 3212 controls the power of the energy storage converter PCS to charge the battery cluster BC to reduce the power, or controls the power of the energy storage converter PCS to discharge to the AC bus 3211 to reduce the power. This application embodiment does not limit this.

[0065] The energy storage system 300 provided in this application embodiment is prone to overcurrent faults when the current in the AC busbar 3211 exceeds the current limit, which may cause safety hazards such as line overheating and device damage. Therefore, when the sum of the AC terminal current of the energy storage converter PCS and the input terminal current of the auxiliary power converter APC is greater than or equal to the first current threshold I1, the controller 3212 controls the energy storage converter PCS to operate at a reduced rate, thereby avoiding overcurrent faults. At the same time, it does not control the auxiliary power converter APC to operate at a reduced rate, so that the power supply requirements of the auxiliary equipment AE can continue to be met.

[0066] In one implementation, reference Figure 5 The energy storage system 300 also includes a system controller 330. Taking the low-voltage interface of the prefabricated substation 310 connected to multiple energy storage boxes (321 and 322) as an example, the system controller 330 is used to control the power reduction of the energy storage converter PCS in each energy storage box (331 and 332) connected to the low-voltage interface of the prefabricated substation 310 when the current of the low-voltage interface of the prefabricated substation 310 is greater than or equal to the second current threshold I2. In this embodiment of the application, the specific value of the second current threshold I2 is not limited.

[0067] In one embodiment, the system controller 330 controls the power reduction of the energy storage converter PCS in each energy storage box (331 and 332) connected to the low-voltage interface of the box-type substation 310. Taking energy storage box 321 as an example, this includes: the system controller 330 controlling the power of the energy storage converter PCS in energy storage box 321 to charge the battery cluster BC to reduce the power, or controlling the power of the energy storage converter PCS in energy storage box 321 to discharge the AC busbar 3211 to reduce the power. This application embodiment does not limit this aspect.

[0068] As described above, the energy storage system 300 provided in this application embodiment is prone to overcurrent faults when the current in the AC busbar 3211 is too large. Therefore, when the low-voltage interface current of the prefabricated substation 310 is greater than or equal to the second current threshold I2, the system controller 330 controls the energy storage converter PCS in each energy storage box (331 and 332) connected to the low-voltage interface of the prefabricated substation 310 to operate at a reduced rate, thereby avoiding overcurrent faults. At the same time, the auxiliary power converter APC in each energy storage box is not controlled to operate at a reduced rate, so that the power supply requirements of the auxiliary equipment AE can continue to be met.

[0069] In one implementation, Figure 5 Based on the energy storage system 300 shown, each energy storage box also includes a switch, such as... Figure 6 The diagram shows a circuit topology of another energy storage system 300 provided in this application embodiment. Continuing with the example of energy storage box 321, energy storage box 321 also includes a switch K, and the auxiliary power converter APC in energy storage box 321 is connected to AC bus 3211 via switch K. Alternatively, the auxiliary power converter APC can be connected to AC bus 3211 via a plug-in method.

[0070] In one embodiment, the energy storage box 321 includes a switch K, one end of which is connected to the input terminal of the auxiliary power converter APC, and the other end of which is connected to the AC busbar 3211 via an open terminal (OT).

[0071] In one embodiment, switch K can be a manual switch or an electric switch; this application does not limit the specific type of switch.

[0072] The energy storage system 300 provided in this application embodiment has an auxiliary power converter (APC) connected to an AC bus 3211 via a switch K. Disconnecting the APC from the AC bus 3211 by disconnecting switch K facilitates fault isolation, flexible switching, and equipment protection. Alternatively, the APC can be connected to the AC bus 3211 using a quick-plug method, enabling rapid disassembly and maintenance, flexible equipment deployment, simplified wiring procedures, and improved operational efficiency and ease of use.

[0073] In one implementation, continue to refer to Figure 3 and Figure 4 Multiple energy storage boxes (321 and 322) connected in series form a group of energy storage boxes. The energy storage system 300 includes at least two groups of energy storage boxes. For example, the energy storage system 300 includes two groups of energy storage boxes, with energy storage boxes 321 and 322 forming one group and energy storage boxes 323 and 324 forming another group. The low-voltage interface of the prefabricated substation 310 includes at least two sets of low-voltage interfaces. The AC busbar of the energy storage box at the end of the series path of each of the at least two sets of energy storage boxes is connected one-to-one with the low-voltage interfaces of the at least two sets of prefabricated substations. For example, the transformer T in the prefabricated substation 310 is a low-voltage double-split three-winding transformer. The transformer T includes one medium-voltage winding and two low-voltage windings coupled to the one medium-voltage winding. The low-voltage interface of the prefabricated substation 310 includes two sets of low-voltage interfaces. The energy storage box 322 is the energy storage box at the end of the series path of one set of energy storage boxes. The AC busbar 3221 of the energy storage box 322 is connected to the low-voltage interface of one set of prefabricated substations 110. The energy storage box 323 is the energy storage box at the end of the series path of another set of energy storage boxes. The AC busbar 3231 of the energy storage box 323 is connected to the low-voltage interface of another set of prefabricated substations 110.

[0074] In one implementation, continue to refer to Figure 3 and Figure 4 The energy storage system 100 may also include two sets of energy storage boxes. Energy storage boxes 325 and 326 form one set of energy storage boxes, and energy storage boxes 327 and 328 form the other set of energy storage boxes. For specific connection relationships, please refer to [reference needed]. Figure 3 and Figure 4 The embodiments of this application will not be described in detail here.

[0075] The energy storage system 300 provided in this application embodiment, by adopting the above connection method, can block the DC and AC circulating currents between the energy storage boxes connected to the low-voltage interfaces of at least two sets of prefabricated substations, thereby reducing losses and heat generation and preventing fault propagation. Furthermore, the energy storage boxes connected to the low-voltage interfaces of at least two sets of prefabricated substations can be independently scheduled and put into operation or decommissioned in stages, improving the reliability and operational flexibility of the energy storage system 300.

[0076] Reference Figures 3 to 6Continuing with the example of energy storage box 321, this embodiment of the application also provides an energy storage box 321, which includes an energy storage converter PCS, a battery cluster BC, an auxiliary power converter APC, an AC busbar 3211, and auxiliary equipment AE. The energy storage converter PCS converts the electrical energy from the battery cluster BC into power and outputs it to the AC busbar 3211. The auxiliary power converter APC draws power from the AC busbar 3211 to supply power to the auxiliary equipment AE. The AC busbar 3211 of the energy storage box 321 outputs electrical energy to the low-voltage interface of the prefabricated substation 310. The prefabricated substation 310 boosts the voltage of the electrical energy received at the low-voltage interface and transmits it to the power grid 200.

[0077] In one embodiment, the auxiliary equipment AE in the energy storage box 321 includes a liquid cooling unit, a fire protection system, lighting equipment, or monitoring equipment.

[0078] In one implementation, continue to refer to Figures 3 to 6 The energy storage box 321 includes multiple energy storage converters PCS and multiple battery clusters BC. The multiple energy storage converters PCS and multiple battery clusters BC included in the energy storage box 321 are electrically connected in a one-to-one correspondence. The multiple energy storage converters PCS are arranged along the length direction of the energy storage box BC, and the AC busbar 3211 extends along the length direction of the energy storage.

[0079] The detailed description of the energy storage system 300 and the analysis of its beneficial effects described above can be applied to the energy storage box 321, and will not be repeated here in the embodiments of this application.

[0080] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An energy storage system, characterized in that, The energy storage system includes a prefabricated substation and multiple energy storage boxes; Each energy storage box includes an energy storage converter, a battery cluster, an AC busbar, an auxiliary power converter, and auxiliary equipment. The AC buses of the multiple energy storage boxes are connected in series. The AC busbar of the energy storage box at the end of the series path is used to output electrical energy to the low-voltage interface of the prefabricated substation. The prefabricated substation is used to boost the electrical energy received at the low-voltage interface. The energy storage converter is used to convert the electrical energy of the battery cluster into power and output it to the AC busbar. The auxiliary power converter is used to draw power from the AC busbar to supply power to the auxiliary equipment.

2. The energy storage system according to claim 1, characterized in that, The plurality of energy storage boxes are arranged at intervals along the length of the energy storage box. Each energy storage box and an adjacent energy storage box have openings on their opposite side walls. An AC busbar inside the energy storage box extends along the length of the energy storage box, and one end of the AC busbar of the energy storage box is connected in series with one end of the AC busbar of the adjacent energy storage box through the opening.

3. The energy storage system according to claim 1 or 2, characterized in that, The medium-voltage interface of the prefabricated substation is used to connect to the power grid; The prefabricated substation is used to: when the voltage of the power grid is greater than or equal to a voltage threshold, convert the AC power supplied by the power grid and output the electrical energy to the AC busbar.

4. The energy storage system according to claim 1 or 3, characterized in that, The battery clusters in the energy storage box are used to discharge to the AC busbar of the energy storage box when the state of charge (SOC) of the energy storage box is greater than or equal to the SOC threshold, so that the auxiliary power converter in the energy storage box can draw power from the AC busbar.

5. The energy storage system according to any one of claims 1-4, characterized in that, The plurality of energy storage boxes include a first energy storage box and a second energy storage box, wherein one end of the AC busbar of the first energy storage box is connected in series with one end of the AC busbar of the second energy storage box; The second energy storage box is used to: discharge the battery clusters in the second energy storage box to the AC busbar of the second energy storage box when the SOC of the battery clusters in the first energy storage box is less than the SOC of the battery clusters in the second energy storage box, so that the auxiliary power converter in the first energy storage box draws power from the AC busbar of the first energy storage box.

6. The energy storage system according to any one of claims 1-5, characterized in that, Each of the energy storage boxes also includes a controller; The controller is configured to reduce the power of the energy storage converter when the sum of the AC terminal current of the energy storage converter and the input terminal current of the auxiliary power converter is greater than or equal to a first current threshold.

7. The energy storage system according to any one of claims 1-6, characterized in that, The energy storage system also includes a system controller; The system controller is used to control the power reduction of the energy storage converter in each energy storage box connected to the low-voltage interface of the prefabricated substation when the low-voltage interface current of the prefabricated substation is greater than or equal to a second current threshold.

8. The energy storage system according to any one of claims 1-7, characterized in that, Each of the energy storage boxes also includes a switch, through which the auxiliary power converter is connected to the AC busbar; Alternatively, the auxiliary power converter can be connected to the AC busbar via a plug-in connection.

9. The energy storage system according to any one of claims 1-8, characterized in that, The multiple energy storage boxes connected in series form a group of energy storage boxes, and the energy storage system includes at least two groups of energy storage boxes; The low-voltage interface of the prefabricated substation includes at least two sets of low-voltage interfaces. The AC busbar of the energy storage box at the end of the series path of each of the at least two sets of energy storage boxes is connected to the low-voltage interface of the at least two sets of prefabricated substations in a one-to-one correspondence.

10. An energy storage box, characterized in that, The energy storage box includes an energy storage converter, a battery cluster, an auxiliary power converter, an AC busbar, and auxiliary equipment; The energy storage converter is used to convert the electrical energy of the battery cluster into power and output it to the AC bus. The auxiliary power converter is used to draw power from the AC bus to supply power to the auxiliary equipment. The AC busbar of the energy storage box is used to output electrical energy to the low-voltage interface of the prefabricated substation, and the prefabricated substation is used to boost the electrical energy received by the low-voltage interface.

11. The energy storage box according to claim 10, characterized in that, The energy storage box includes multiple energy storage converters and multiple rows of battery clusters. The multiple energy storage converters and multiple rows of battery clusters are electrically connected in a one-to-one correspondence. The multiple energy storage converters are arranged along the length direction of the energy storage box, and the AC busbar extends along the length direction of the energy storage box.

Images