String type current transforming and boosting all-in-one machine and electrochemical energy storage system

Abstract

The utility model discloses a string type converting and boosting all-in-one machine and an electrochemical energy storage system. The string type current transforming and boosting all-in-one machine comprises an auxiliary transformer module, a low-voltage power distribution cabinet, a phase-shifting transformer module and a plurality of energy storage converter assemblies, each energy storage converter assembly is used for being connected with a battery cluster, and the phase-shifting transformer module comprises a primary winding and a plurality of secondary windings. Each secondary winding is connected to one energy storage converter assembly; the primary winding is connected with an external power grid, the primary side access end of the auxiliary transformer module is connected with the alternating current access end of the energy storage converter assembly, and the secondary side access end of the auxiliary transformer module is connected with the power access end of the low-voltage power distribution cabinet; and the power output end of the low-voltage power distribution cabinet is connected with a power utilization module included in the string type converting and boosting all-in-one machine so as to supply power to the power utilization module. According to the technical scheme, harmonic pollution to an external power grid caused by the electrochemical energy storage system where the string type converting and boosting all-in-one machine is located can be effectively reduced.

Description

[0001] This application claims priority to Chinese Patent Application No. 202311544429.2, filed on November 17, 2023, entitled “A String Converter-Boost Transformer and Electrochemical Energy Storage System”, the contents of which are incorporated herein by reference. Technical Field

[0002] This utility model relates to the field of electrochemical energy storage technology, and in particular to a string converter boost converter integrated machine and an electrochemical energy storage system. Background Technology

[0003] With the rapid development of electrochemical energy storage technology, electrochemical energy storage, especially DC energy storage, has become an important component of the power system. Electrochemical energy storage stores energy by converting chemical energy and electrical energy through chemical reactions. When there is a power surplus, the energy storage battery is charged using electricity from the external power grid, and when there is a power shortage, the energy from the energy storage battery supplies power to the external power grid.

[0004] Traditional technologies often employ distributed energy storage systems (DES) for electrochemical energy storage. These DES typically connect individual battery clusters to the DC side of a Power Conversion System (PCS). The AC sides of several PCS converters are then connected in parallel and fed into a step-up transformer to convert the DC power from the batteries into AC power, which is then boosted to supply power to the external grid. When multiple PCS converters are connected in parallel to the step-up transformer for grid connection, especially when the DES is connected to a weak grid, the impedance of the transmission lines creates a complex impedance network between the multiple PCS converters and the external grid. The output current of each PCS converter is not only affected by its own output voltage but also interacts with the output voltages of other PCS converters in the DES and the grid voltage, leading to more complex resonance characteristics and generating harmonics that pollute the external grid. Utility Model Content

[0005] In view of this, this application provides a string converter boost converter and an electrochemical energy storage system, the main purpose of which is to solve the technical problem that the current energy storage system generates too many harmonics during operation, resulting in excessive pollution to the external power grid connected to the grid.

[0006] According to a first aspect of the present invention, a string converter-boost integrated unit is provided, comprising: a phase-shifting transformer module, an auxiliary transformer module, a low-voltage distribution cabinet, and multiple energy storage converter components, wherein the phase-shifting transformer module comprises a primary winding and a secondary winding of the phase-shifting transformer, the primary winding of the phase-shifting transformer comprises a primary winding, and the secondary winding of the phase-shifting transformer comprises multiple secondary windings;

[0007] The energy storage converter assembly has a DC input terminal and an AC input terminal. The DC input terminal is used to connect to an external battery cluster, and the AC input terminal is connected to one of the secondary windings. Each AC input terminal corresponds one-to-one with a secondary winding.

[0008] The primary winding of the phase-shifting transformer module is used to connect to an external power grid for power interaction with the external power grid.

[0009] The primary side of the auxiliary transformer module is connected to the AC input of the energy storage converter assembly, the secondary side of the auxiliary transformer module is connected to the power input of the low-voltage distribution cabinet, and the power output of the low-voltage distribution cabinet is connected to the power consumption module included in the string converter step-up unit.

[0010] In an optional embodiment, the string converter-boost integrated unit further includes a high-voltage ring main unit; the power input terminal of the high-voltage ring main unit is connected to the primary winding of the phase-shifting transformer module, and the power output terminal of the high-voltage ring main unit is used to connect to the external power grid to introduce the high-voltage AC power from the primary winding of the phase-shifting transformer into the external power grid or to introduce the high-voltage AC power from the external power grid into the primary winding of the phase-shifting transformer. The high-voltage ring main unit is also used to keep the string converter-boost integrated unit in a disconnected or connected state with the external power grid.

[0011] In an optional embodiment, the phase-shifting transformer module further includes an iron core disposed between the primary winding and the secondary winding of the phase-shifting transformer, so that the primary winding and each of the secondary windings can perform power conversion through magnetic core coupling.

[0012] In an optional embodiment, the plurality of secondary windings of the phase-shifting transformer are electrically isolated from each other.

[0013] In an optional embodiment, the energy storage converter assembly includes an energy storage converter module and a circuit protection module; the DC input terminal of the energy storage converter module is used to connect to the battery cluster, the power interaction terminal of the energy storage converter module is connected to the first input terminal of the circuit protection module, and the second input terminal of the circuit protection module is connected to one of the secondary windings of the phase-shifting transformer.

[0014] In an optional embodiment, the control signal interaction terminal of the low-voltage distribution cabinet is connected to the control signal interaction terminals of the phase-shifting transformer module, the high-voltage ring network cabinet, the energy storage converter module, and the circuit protection module, respectively.

[0015] In an optional embodiment, the low-voltage distribution cabinet has a remote interface connection terminal for connecting to a remote host computer.

[0016] In an optional embodiment, the energy storage converter module and the circuit protection module are housed in the cabinet of the string converter-boost unit.

[0017] In an optional embodiment, each of the secondary windings has a different phase shift angle.

[0018] According to a second aspect of the present invention, an electrochemical energy storage system is provided, comprising the aforementioned string converter-boost integrated machine, and further comprising multiple battery clusters, wherein the battery input terminal of each battery cluster is connected to the DC input terminal of one of the energy storage converter components of the string converter-boost integrated machine, wherein the battery cluster is composed of multiple cells connected in series, and each battery cluster is respectively connected to a different energy storage converter component.

[0019] This utility model provides a string converter-boost integrated unit and an electrochemical energy storage system. A phase-shifting transformer is configured on the AC side of the string converter-boost integrated unit as a phase-shifting transformer module, and the secondary side of the phase-shifting transformer module has multiple windings. Furthermore, the AC sides of multiple energy storage converter components are respectively connected to multiple secondary windings with different phase shift angles. Here, by separating the AC sides of different energy storage converter components from each other instead of connecting them to a single secondary winding, the output voltage interaction caused by multiple energy storage converter components being connected to a single secondary winding in the energy storage system is avoided, thus preventing harmonics generated. This can better reduce harmonics output on the grid-connected side, significantly reducing harmonics output on the transformer's grid-connected side, and effectively reducing the pollution of the external power grid caused by harmonics generated by the energy storage system. Furthermore, by obtaining power from the energy storage converter assembly through the auxiliary transformer module and the low-voltage distribution cabinet, the power is supplied to each electrical module in the string converter-boost integrated machine. Compared with the existing method of drawing power from the external power grid to supply power to each electrical module, the technical solution of this application can obtain power from the battery cluster connected to the energy storage converter assembly to supply power to the electrical modules even when the external power grid is abnormal, thereby improving the operational stability of the string converter-boost integrated machine.

[0020] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0022] Figure 1 This diagram illustrates the structure of a string converter boost converter integrated unit provided in an embodiment of the present invention.

[0023] Figure 2 This diagram illustrates the structure of a phase-shifting transformer module according to an embodiment of the present invention.

[0024] Figure 3 This invention provides a schematic diagram of another string converter boost converter provided in an embodiment of the present invention.

[0025] Figure 4 A side view of a string converter boost converter provided in an embodiment of the present invention is shown. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0027] Currently, distributed energy storage systems are widely used in the field of electrochemical energy storage. These systems typically connect individual battery clusters to the DC side of a Power Conversion System (PCS), while the AC sides of several PCS converters are connected in parallel to a step-up transformer. This converts the DC power from the batteries into AC power and then boosts the AC voltage to supply power to the grid. When multiple PCS converters are connected in parallel to the step-up transformer for grid connection, especially when the distributed energy storage system is connected to a weak grid, a complex impedance network is formed between the multiple PCS converters and the external grid, considering the influence of transmission line impedance. The output current of each PCS converter is not only affected by its own output voltage but also interacts with the output voltages of other PCS converters in the distributed energy storage system and the grid voltage. This leads to more complex resonance characteristics induced by the distributed energy storage system, generating harmonics that are output to the external grid and causing pollution. Furthermore, in distributed energy storage systems including parallel PCS converters, during transient processes such as sudden changes in external load or fluctuations in renewable energy output power, differences in hardware parameters, control parameters, and external line parameters between PCS converters can cause circulating current and power unevenness. Additionally, the resonant spikes in the circulating current admittance can lead to resonance in the circulating current between PCS converters, thus affecting the stable operation of the entire distributed energy storage system and causing serious pollution to the external power grid connected to the distributed energy storage system. In severe cases, this can lead to resonant power outages. Furthermore, insulation testing of distributed energy storage systems requires measuring the insulation impedance of a cluster of batteries connected to a single PCS converter. When multiple PCS converters are connected in parallel, the insulation system used for insulation testing cannot accurately detect the insulation impedance value of a single energy storage subsystem.

[0028] Furthermore, when the energy storage system is off-grid, each string PCS converter operates in parallel in voltage source mode to drive the load of the energy storage system. The output current of each PCS converter consists of two parts: one part flows into the load to supply power, and the other part is the system circulating current flowing between the PCS converters. The circulating current generated between the PCS converters is mainly affected by the reference voltage and the system transfer function. Therefore, differences in component parameters, control parameters, and reference voltage settings of each PCS converter will all cause system circulating current. Differences in output voltage and equivalent output impedance will lead to circulating current and uneven power distribution in the parallel system, affecting the operational stability of the energy storage system.

[0029] Furthermore, current centralized energy storage systems often use parallel connection of multiple battery clusters to centrally connect to a centralized energy storage converter in order to increase the overall battery capacity. However, due to inconsistencies in parameters such as internal resistance, capacity, voltage, and temperature among the individual battery clusters, potential differences exist between the parallel clusters. Therefore, parallel connection of battery clusters leads to circulating currents, causing energy to flow from high-voltage clusters to low-voltage clusters. The voltages of the clusters are forced to balance. When a cluster with lower internal resistance is fully charged or discharged, other clusters must stop charging and discharging. This results in incomplete charging and discharging of battery clusters, easily causing battery capacity loss and temperature increases, accelerating battery degradation, and reducing the usable capacity of the battery system. In addition, excessive temperature differences between individual cells further exacerbate the inconsistencies in internal resistance and capacity, leading to accelerated cell degradation, shortening the cycle life of the battery system, and even creating safety hazards.

[0030] To address the above problems, in one embodiment, such as Figure 1 As shown, a string converter-boost integrated unit is provided. This string converter-boost integrated unit is part of an electrochemical energy storage system and is connected between the battery and the grid connection point. The following description uses an application of this string converter-boost integrated unit to an electrochemical energy storage system using three-phase power as an example; other electrochemical energy storage systems with different power transmission methods are also applicable to this embodiment. Further, the string converter-boost integrated unit includes a phase-shifting transformer module 100, an auxiliary transformer module 300, a low-voltage distribution cabinet 400, and multiple energy storage converter components 200. The energy storage converter components 200 can be arranged in two rows facing each other within the space inside the integrated unit. Each energy storage converter component 200 has a DC input terminal and an AC input terminal. The DC input terminal is used to connect to an external battery cluster (not shown in the figure). Here, the phase-shifting transformer module 100 can be a phase-shifting transformer, which is a type of rectifier transformer. Its different secondary windings have different phases and are connected to the rectifier circuit of a high-voltage frequency converter to form a multi-phase rectifier system, which can reduce harmonic currents on the grid side.

[0031] Among them, such as Figure 2As shown, the phase-shifting transformer module 100 includes a primary winding 110 and a secondary winding 120. The primary winding 110 includes a primary winding 111, and the secondary winding 120 includes multiple secondary windings 121. Each secondary winding 121 in the secondary winding 120 has a different phase shift angle, and the AC input terminal of the energy storage converter assembly 200 is connected to one of the secondary windings 121 in the secondary winding 120. The multiple secondary windings 121 in the secondary winding 120 are electrically isolated from each other, and each secondary winding 121 can be configured with a different phase shift angle using the principle of extended delta phase shifting. As an example, if the number of energy storage converter components 200 in the string converter-boost integrated unit is 5, the AC input terminal of the AC side of each energy storage converter component 200 can be connected to different secondary windings 121 in the secondary winding 120 of the phase-shifting transformer, so that the AC sides of different energy storage converter components 200 are not connected in parallel. Here, if the power transmission form of the system where the string converter-boost integrated unit is located is three-phase, the primary winding 111 of the primary winding 110 of the phase-shifting transformer can contain 3 winding coils and output phase A, phase B and phase C power. The form of the secondary winding 121 connected to the AC side of the energy storage converter component 200 can refer to the primary winding 111, and will not be described in detail here. Furthermore, the phase-shifting transformer module 100 also includes a core 130, which is disposed between the primary winding 110 and the secondary winding 120 of the phase-shifting transformer. This allows for power conversion between the primary winding 111 and each of the secondary windings 121 via magnetic core coupling, supporting either grid-connected or independent off-grid operation of the string converter-boost unit. Furthermore, the energy storage converter assembly 200 can be a string PCS, with the number of string PCS matching the number of secondary windings included in the phase-shifting transformer module 100.

[0032] It should be noted that each of the energy storage converter components 200 is connected to a different secondary winding 121 in the secondary winding 120 of the phase-shifting transformer. Each energy storage converter component 200 is connected to a corresponding secondary winding 121, and there is no situation where multiple energy storage converter components 200 are connected to the same secondary winding 121. Here, by separating the AC sides of different energy storage converter components 200 from each other, the system prevents multiple energy storage converter components 200 from being connected to the same secondary winding 121, which could lead to output voltage interaction and harmonic generation. Meanwhile, the more secondary windings 121 with different phase shift angles the phase-shifting transformer module 100 has, the better it can reduce the harmonics output on the grid-connected side, thus significantly reducing the harmonics output on the grid-connected side of the transformer. Here, the energy storage converter assembly 200 is used to convert the DC power used by the energy storage converter assembly 200 to charge and discharge the battery cluster into low-voltage AC power for power interaction between the energy storage converter assembly 200 and the phase-shifting transformer module 100. The phase-shifting transformer module 100 is used to convert the low-voltage AC power of the secondary winding 120 of the phase-shifting transformer into the high-voltage AC power of the primary winding 110 of the phase-shifting transformer.

[0033] Furthermore, the primary winding 111 of the phase-shifting transformer module 100 is used to connect to an external power grid (not shown in the figure) to introduce the high-voltage AC power from the primary winding 110 of the phase-shifting transformer into the external power grid or to introduce the high-voltage AC power from the external power grid into the primary winding 110 of the phase-shifting transformer. The external power grid can be a power system connected to the electrochemical energy storage system where the string converter-boost unit is located.

[0034] Furthermore, the primary side connection of the auxiliary transformer module 300 is connected to the AC connection of the energy storage converter assembly 200, the secondary side connection of the auxiliary transformer module 300 is connected to the power connection of the low-voltage distribution cabinet 400, and the power output of the low-voltage distribution cabinet 400 is connected to the power supply connection of the power consumption module (not shown in the figure) included in the string converter-boost integrated machine. The power consumption module can be a load installed on the string converter-boost integrated machine, such as a current sensor, temperature sensor, and voltage sensor.

[0035] Here, the auxiliary transformer module 300 is used to obtain low-voltage AC power from the AC input terminal of the energy storage converter assembly 200, convert the obtained low-voltage AC power into a power supply of the voltage level required by each power consumption module included in the string converter step-up unit, and send the power supply to the low-voltage distribution cabinet 400 so that the low-voltage distribution cabinet 400 can distribute power to the power consumption modules connected to the low-voltage distribution cabinet 400. As an example, if the voltage of the AC input terminal of the energy storage converter assembly 200 is 690V, and the power consumption module requires a 220V power supply, the auxiliary transformer module 300 can connect 690V AC power to the primary winding, convert the 690V AC power into 220V AC power, and output a 220V power supply to the low-voltage distribution cabinet 400 at the secondary winding; furthermore, after receiving the 220V power supply, the low-voltage distribution cabinet 400 can distribute the power supply to the power consumption modules that need power.

[0036] Here, the winding configuration of the auxiliary transformer module 300 can be set according to the voltage level required by the power consumption module, so that the auxiliary transformer module 300 can output the power supply voltage required by the power consumption module. Furthermore, the low-voltage distribution cabinet 400 is connected to the power supply output of the auxiliary transformer module 300 and distributes the power supply to each power consumption module of the string converter-boost integrated unit, providing auxiliary power distribution for the string converter-boost integrated unit.

[0037] The string converter-boost integrated unit provided in this embodiment features a phase-shifting transformer module configured on the AC side of the unit. The secondary side of this phase-shifting transformer module has multiple windings. Furthermore, the AC sides of multiple energy storage converter components are connected to multiple secondary windings with different phase shift angles. Here, by separating the AC sides of different energy storage converter components from each other instead of connecting them to a single secondary winding, the interaction of output voltage caused by multiple energy storage converter components sharing a single secondary winding in the energy storage system is avoided, thus preventing harmonics. This better reduces harmonics output on the grid-connected side, significantly reducing harmonics output on the transformer's grid-connected side, and effectively minimizing pollution to the external power grid caused by harmonics generated by the energy storage system. Furthermore, by obtaining power from the energy storage converter components through the auxiliary transformer module and the low-voltage distribution cabinet, the power is supplied to each power consumption module in the string converter-boost integrated machine. Compared with the existing method of drawing power from the external power grid to supply power to each power consumption module, the technical solution of this application can obtain power from the battery cluster to supply power to the power consumption module even when the external power grid is abnormal, thereby improving the operational stability of the string converter-boost integrated machine.

[0038] In one embodiment, such as Figure 3As shown, the string converter-boost integrated unit also includes a high-voltage ring main unit 500. The high-voltage ring main unit 500 can control the switching of the high-voltage side of the integrated unit. In power systems, the high-voltage side voltage is usually very high, therefore a dedicated switching device is needed to control the connection and disconnection of the power supply to ensure the safe and stable operation of the power system. Specifically, the power input terminal of the high-voltage ring main unit 500 is connected to the primary winding of the phase-shifting transformer module 100, and the power output terminal of the high-voltage ring main unit 500 is used to connect to the external power grid (not shown in the figure) to introduce the high-voltage AC power from the primary winding of the phase-shifting transformer into the external power grid or to introduce the high-voltage AC power from the external power grid into the primary winding of the phase-shifting transformer. Furthermore, the high-voltage ring main unit 500 is also used to keep the string converter-boost integrated unit in a disconnected or connected state with the external power grid. Specifically, the high-voltage ring main unit 500 can control the connection and disconnection of the grid connection point to ensure the safe and stable operation of the power system. The embodiments provided in this application enable switching control of the high-voltage side of the string converter-boost integrated machine based on the high-voltage ring main unit. When the electrochemical energy storage system where the string converter-boost integrated machine is located is storing energy for the battery cluster or supplying power to the external power grid, the power output terminal of the high-voltage ring main unit is connected to the external power grid. When the energy storage system needs to be operated off-grid, the power output terminal of the high-voltage ring main unit is disconnected from the external power grid, ensuring the operational reliability of the power system.

[0039] In one embodiment, the energy storage converter assembly includes an energy storage converter module and a circuit protection module. Here, the energy storage converter module is a device for bidirectional AC / DC power conversion, and the circuit protection module can be a molded case circuit breaker, fuse, or similar device. Specifically, the DC input terminal of the energy storage converter module is connected to the battery cluster, the power interaction terminal of the energy storage converter module is connected to the first input terminal of the circuit protection module, and the second input terminal of the circuit protection module is connected to one of the secondary windings of the phase-shifting transformer. Here, the DC side of the energy storage converter module obtains DC power from the battery cluster through connection to the battery cluster and converts it to AC power, which is then sent to the circuit protection module for overcurrent and short-circuit protection. The second input terminal of the circuit protection module is connected to one of the secondary windings of the phase-shifting transformer in the phase-shifting transformer module. Specifically, as shown... Figure 4As shown, the energy storage converter module 210 and the circuit protection module 220 are disposed in the cabinet of the string converter-boost integrated machine. The energy storage converter modules 210 in the energy storage converter assembly can be centrally disposed in the upper half of the cabinet 600 included in the integrated machine. The AC side of each energy storage converter module 210 can be connected to the circuit protection module 220 located in the lower half of the cabinet 600. The wires from the energy storage converter module 210 to the circuit protection module 220 of each energy storage converter assembly can be arranged inside the cabinet 600.

[0040] Furthermore, the control signal interaction terminals of the low-voltage distribution cabinet are respectively connected to the control signal interaction terminals of the phase-shifting transformer module, the high-voltage ring main unit, the energy storage converter module, and the circuit protection module, for controlling the operating status of the phase-shifting transformer module, the high-voltage ring main unit, the circuit protection module, and the energy storage converter module. The embodiments provided in this application can set a corresponding circuit protection module for each energy storage converter module, providing overcurrent and short-circuit breaking protection for the energy storage converter module, thus improving the working stability of the string converter-boost integrated unit.

[0041] In one embodiment, the low-voltage distribution cabinet has a remote interface connection terminal for connecting to a remote host computer. The host computer can be upstream equipment in the power system, such as a power station EMS, or a control terminal in a remote control center. This allows the string converter booster unit to interact with the host computer (e.g., the power station EMS) through the low-voltage distribution cabinet, enabling relevant personnel to remotely control the string converter booster unit. Furthermore, the remote interface connection terminal can be connected to the battery compartment to establish data interaction, allowing relevant personnel to operate the entire electrochemical energy storage system based on the string converter booster unit, thus improving the control capability of the entire electrochemical energy storage system. The embodiments provided in this application enable connection between the remote interface connection terminal of the low-voltage distribution cabinet and various remote control devices and the host computer, allowing relevant personnel to remotely control the string converter booster unit and related equipment connected to it, thereby improving the control capability of the electrochemical energy storage system. Furthermore, the string converter-step-up unit can internally provide isolated installation spaces for the phase-shifting transformer module, multiple energy storage converter components, high-voltage ring main unit, auxiliary transformer module, and low-voltage distribution cabinet, ensuring that the modules do not interfere with each other. The connecting lines between modules can also be located inside the string converter-step-up unit. Furthermore, the connection methods for the phase-shifting transformer module, multiple energy storage converter components, high-voltage ring main unit, auxiliary transformer module, and low-voltage distribution cabinet can be found in the textual description of the embodiments.

[0042] The string converter-boost integrated unit provided in this embodiment features a phase-shifting transformer module on the AC side, with multiple windings on the secondary side. Furthermore, the AC sides of multiple energy storage converter components are connected to secondary windings with different phase-shift angles. Each secondary winding employs an extended delta phase-shifting principle to set a different phase-shift angle. The more secondary windings with different phase-shift angles in the phase-shifting transformer module, the better the harmonics output from the grid-connected side can be reduced, significantly decreasing the harmonics output from the transformer's grid-connected side, thereby effectively reducing the pollution of the external power grid caused by harmonics generated by the energy storage system. Furthermore, by connecting the AC side of each energy storage converter component in the string converter-boost integrated unit to separate secondary windings in the phase-shifting transformer module, a complex impedance network between the energy storage converter components and the external power grid is avoided. This prevents the output current of each energy storage converter component from being affected by its own output voltage and avoids coupling effects with the output voltage of other energy storage converter components in the string converter-boost integrated unit and the grid voltage. This reduces harmonics output by the electrochemical energy storage system containing the string converter-boost integrated unit to the external power grid, thus reducing pollution to the external power grid. Simultaneously, separating the secondary windings corresponding to each energy storage converter component avoids system circulating currents caused by differences in component parameters, control parameters, and inconsistent reference voltage settings. This also prevents circulating currents and power imbalances caused by differences in output voltage and equivalent output impedance, thereby improving the operational stability of the energy storage system. Furthermore, because the low-voltage side of the phase-shifting transformer module has multiple secondary windings where the secondary winding of the phase-shifting transformer is located, and each secondary winding is isolated from the others, there is no parallel connection of the secondary windings connected to the AC side of each energy storage converter component. Therefore, there is no circulating current phenomenon between energy storage converter components and the insulation detection accuracy of a single energy storage subsystem is improved.

[0043] Furthermore, this embodiment provides an electrochemical energy storage system, which includes the aforementioned string converter-boost integrated unit. The electrochemical energy storage system also includes multiple battery clusters. The battery input terminal of each battery cluster is connected to the DC input terminal of one of the energy storage converter components. Each battery cluster consists of multiple cells connected in series, and each battery cluster is connected to a different energy storage converter component. Here, each battery cluster may include multiple cells connected in series, and each battery cluster is connected to the DC input terminal of an energy storage converter component. Each battery cluster is connected to a different energy storage converter component. When the electrochemical energy storage system is storing energy, the high-voltage ring main unit is connected to the external power grid. The high-voltage AC power from the external power grid flows through the high-voltage ring main unit into the primary winding of the phase-shifting transformer module. The secondary windings of the phase-shifting transformer output multiple low-voltage AC power after step-down. Each low-voltage AC power flows through the circuit protection module of an energy storage converter component into the AC side of the energy storage converter module. After AC-to-DC conversion by the energy storage converter module, it is sent to the battery cluster from the DC side. Conversely, when the electrochemical energy storage system supplies power to the external power grid, the high-voltage ring main unit is connected to the grid-connected external power grid. Each battery cluster outputs DC power to the energy storage converter module connected to that battery cluster. The energy storage converter module converts the DC power to AC power to obtain low-voltage AC power. The low-voltage AC power is then sent from the AC side of the energy storage converter module to a secondary winding corresponding to that energy storage converter module via the circuit protection module. Further, the phase-shifting transformer module converts the low-voltage AC power into high-voltage AC power, and the primary winding of the phase-shifting transformer sends the high-voltage AC power to the high-voltage ring main unit. The high-voltage ring main unit outputs high-voltage AC power to the grid-connected external power grid.

[0044] The electrochemical energy storage system provided in this embodiment connects the energy storage converter module to each series-connected battery cluster one-to-one, with no parallel connections between the battery clusters. This effectively eliminates the capacity loss caused by circulating current, improves the battery system's capacity utilization, and extends battery life. Simultaneously, by using the energy storage converter module, the traditional centralized energy storage system is broken down into smaller, more modular units. The capacity of each individual energy storage unit is reduced, and they are mutually redundant. When the energy storage converter module or a single battery cluster fails and stops operating, other energy storage units can continue to operate normally, reducing the scope of the fault's impact and improving the overall utilization rate of the energy storage system.

[0045] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0046] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A string type current-voltage boosting integrated machine, characterized in that, The group string type current conversion and voltage boosting integrated machine comprises a phase-shifting transformer module, an auxiliary transformer module, a low-voltage power distribution cabinet and a plurality of energy storage current converter components, wherein the phase-shifting transformer module comprises a phase-shifting transformer primary winding and a phase-shifting transformer secondary winding, the phase-shifting transformer primary winding comprises a primary winding, and the phase-shifting transformer secondary winding comprises a plurality of secondary windings; The energy storage current converter component has a direct current access end and an alternating current access end, the direct current access end is used for accessing a battery cluster outside, and the alternating current access end is connected with one of the secondary windings, and the alternating current access end corresponds to the secondary windings one by one. The primary winding of the phase-shifting transformer module is used for connecting with an external power grid to interact with the external power grid. The primary side access end of the auxiliary transformer module is connected with the alternating current access end of the energy storage current converter component, the secondary side access end of the auxiliary transformer module is connected with the power access end of the low-voltage power distribution cabinet, and the power output end of the low-voltage power distribution cabinet is connected with a power consumption module contained in the group string type current conversion and voltage boosting integrated machine.

2. The string-type current-voltage integrated booster according to claim 1, characterized in that, The group string type current conversion and voltage boosting integrated machine further comprises a high-voltage ring network cabinet. The power access end of the high-voltage ring network cabinet is connected with the primary winding of the phase-shifting transformer module, the power output end of the high-voltage ring network cabinet is used for connecting to the external power grid to introduce high-voltage alternating current of the phase-shifting transformer primary winding into the external power grid or introduce high-voltage alternating current of the external power grid into the phase-shifting transformer primary winding, and the high-voltage ring network cabinet is further used for making the group string type current conversion and voltage boosting integrated machine and the external power grid in a disconnected state or a conductive state.

3. The string-type current-voltage integrated booster according to claim 1, characterized in that, The phase-shifting transformer module further comprises a core, and the core is arranged between the phase-shifting transformer primary winding and the phase-shifting transformer secondary winding to make the primary winding and each of the secondary windings coupled by a magnetic core for power conversion.

4. The string-type current-voltage integrated booster of claim 1, wherein, The plurality of secondary windings of the phase-shifting transformer secondary winding are circuitically isolated from each other.

5. The string-type current-voltage integrated booster of claim 2, wherein, The energy storage current converter component comprises an energy storage current converter module and a circuit protection module. The direct current access end of the energy storage current converter module is used for connecting to the battery cluster, the power interaction end of the energy storage current converter module is connected with the first access end of the circuit protection module, and the second access end of the circuit protection module is connected with one of the secondary windings of the phase-shifting transformer secondary winding.

6. The string-type current-voltage integrated machine according to claim 5, wherein The control signal interaction end of the low-voltage power distribution cabinet is connected with the control signal interaction end of the phase-shifting transformer module, the high-voltage ring network cabinet, the energy storage current converter module and the circuit protection module respectively.

7. The string current-voltage booster all-in-one machine according to claim 1, characterized in that, The low-voltage power distribution cabinet has a remote interface connection end, and the remote interface connection end is used for connecting with a remote host computer.

8. The string-type current-voltage integrated machine according to claim 5, wherein The energy storage current converter module and the circuit protection module are arranged in a cabinet of the group string type current conversion and voltage boosting integrated machine.

9. The string current-voltage booster all-in-one machine according to claim 1, characterized in that, The phase-shifting angles of the secondary windings are different.

10. An electrochemical energy storage system, characterized by The electrochemical energy storage system comprises the group string type current conversion and voltage boosting integrated machine according to any one of claims 1 to 9, and further comprises a plurality of battery clusters, a battery access end of each of the battery clusters being connected to a direct current access end of one of the energy storage current converter assemblies of the group string type current conversion and voltage boosting integrated machine, wherein each of the battery clusters is composed of a plurality of series-connected battery cells, and each of the battery clusters is connected to a different energy storage current converter assembly.

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