Cascaded energy storage power module pair test system and method

Abstract

The application provides a kind of test system and method of cascaded energy storage power module, it is related to electric power test technical field, the architecture of active test mode is: first power module DC side is connected with first battery cluster through first filter module;Second power module DC side is connected with second battery cluster through second filter module;First power module AC side is connected with second power module AC side through opposite drag inductance;Control cabinet is connected with the control panel of first power module and second power module, controls the charge-discharge state of battery and adjusts power;The architecture of reactive test mode is: first power module DC side is connected with DC source, AC side is connected with second power module AC side through opposite drag inductance;Control cabinet is connected with the control panel of first power module and second power module, by adjusting the phase angle and amplitude of AC side output voltage and current, reach that reactive power circulates between the converter of two power modules, constitute closed loop.

Description

Technical Field

[0001] This invention relates to the field of power testing technology, and more particularly to a drag testing system and method for cascaded energy storage power modules. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] Currently, the proportion of power generation from new energy sources continues to increase, but new energy power generation has its own inherent instability. Therefore, power storage converters (PCS) that can "shift peak loads and fill valleys" have emerged. High-power cascaded energy storage devices typically employ chain-type multilevel converter technology, containing dozens or even hundreds of energy storage power modules. Power module-to-module testing is required to evaluate their performance and verify their reliability.

[0004] Based on existing technologies, Option 1: NIO proposes a closed-loop energy storage PCS testing platform, referencing... Figure 7 This scheme uses two sets of PCS connected in series to form a closed-loop energy storage PCS system. With the AC side of the two sets of PCS connected to the power grid, the DC parameters of the two sets of energy storage PCS are adjusted by the charge and discharge control module to simulate the charging and discharging operation of the battery, thereby realizing the mutual drag test between the two sets of energy storage PCS.

[0005] Option 2: Pinggao Group proposed a new PCS testing platform, for reference... Figure 8 This scheme connects the AC side and DC side of the two PCS under test to form a closed loop. By connecting a DC source to the DC side, it avoids direct connection between the two PCS under test and the power grid, thus solving the problem of introducing fault current into the power grid during the test.

[0006] However, the towing platforms built under Schemes 1 and 2 are only suitable for testing the PCS converter and do not include battery testing. For high-power cascaded energy storage devices, in addition to the converter, the reliability of the energy storage battery, the current flowing from the power module to the battery through the filter module, and the filtering effect of the filter module also need to be tested.

[0007] In summary, there is an urgent need for a technical solution that can overcome the above-mentioned shortcomings and enable comprehensive testing of high-power cascaded energy storage devices. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention proposes a drag-and-drop testing system and method for cascaded energy storage power modules.

[0009] In a first aspect of the present invention, a cascaded energy storage power module drag test system is proposed, comprising: a first power module, a second power module, a first filter module, a second filter module, a first battery cluster, a second battery cluster, a control chassis, and a drag inductor;

[0010] When conducting towing tests using the towing test system of this cascaded energy storage power module, the architecture of the active power test mode is as follows:

[0011] The DC side of the first power module is connected to the first battery cluster via the first filter module; the DC side of the second power module is connected to the second battery cluster via the second filter module; the AC side of the first power module is connected to the AC side of the second power module via a pull-out inductor; the control chassis is connected to the control boards of the first and second power modules to control the charging and discharging state of the batteries and adjust the power.

[0012] The architecture of the reactive power testing mode is as follows:

[0013] The DC side of the first power module is connected to a DC source, and the AC side is connected to the AC side of the second power module through a pull-out inductor. The control chassis is connected to the control boards of the first and second power modules. By adjusting the phase angle and amplitude of the AC output voltage and current, reactive power can circulate between the converters of the two power modules, forming a closed loop.

[0014] Furthermore, when conducting towing tests using the towing test system of this cascaded energy storage power module, it also includes:

[0015] Another architecture for reactive power testing mode is:

[0016] The DC side of the first power module is connected to one end of the first filter module, and the other end of the first filter module is connected to a DC source. The AC side of the first power module is connected to the AC side of the second power module through a pull-out inductor. The DC side of the second power module is connected to one end of the second filter module. The control chassis is connected to the control boards of the first and second power modules. By adjusting the phase angle and amplitude of the AC output voltage and current, reactive power can circulate between the converters of the two power modules, forming a closed loop.

[0017] Furthermore, the DC source is obtained by rectifying a three-phase AC power grid connected to a three-phase bridge converter; the three-phase bridge converter uses thyristors or fully controlled power electronic devices.

[0018] Furthermore, the first power module and the second power module are AC / DC converters, used to control the charging and discharging process of the battery and perform AC / DC conversion.

[0019] Furthermore, the first and second filtering modules are used to filter the current flowing into the battery branch, and to perform second harmonic filtering of the voltage, high-frequency current filtering of the switching frequency, and low-frequency oscillation suppression on the DC side of the first and second power modules, respectively.

[0020] Furthermore, the control chassis is powered by the AC power grid and is connected to the control boards of the first power module and the second power module via optical fiber.

[0021] Furthermore, the first and second battery clusters achieve energy transfer within the battery clusters by charging and discharging the batteries.

[0022] In a second aspect of the present invention, a method for testing cascaded energy storage power modules is proposed, which is performed based on a cascaded energy storage power module testing system.

[0023] The method for conducting active power drag testing includes:

[0024] The initial charge levels of the batteries in the first and second battery clusters are adjusted to ensure that the voltage difference between the batteries is within a set threshold range. At the start of the charging process, the charging soft-start circuits at the output terminals of the first and second battery clusters are controlled, and the contactors in the charging soft-start circuits are closed. The first and second battery clusters charge the DC-side capacitors of the first and second power modules and the DC-side capacitors of the first and second filter modules respectively through the soft-start resistors in the charging soft-start circuits. When the charging reaches near steady state, the contactors at the output terminals of the first and second battery clusters are closed, making the DC-side capacitor voltages of the first and second power modules consistent with the output voltages of the first and second battery clusters.

[0025] During the active power supply test, the first control logic of the control box is set. The first power module control mode is a fixed-mode mode, which controls the AC output voltage to a fixed value. The second power module control mode is AC current control, which gives the magnitude of active and reactive current commands. Through the AC current loop, the phase angle and amplitude of the modulation wave of the second power module are controlled to adjust the magnitude and direction of the AC current, thereby further adjusting the magnitude and direction of active and reactive power.

[0026] In a third aspect of the present invention, a method for testing cascaded energy storage power modules is proposed, which is performed based on a cascaded energy storage power module testing system.

[0027] When conducting reactive power drag testing, the method includes:

[0028] The DC-side capacitor of the first power module is charged by a DC source. After charging to the rated state, the second control logic of the control chassis is executed, wherein the control mode of the first power module is a fixed modulation mode. The first power module is unlocked, and the modulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the required value, while the DC-side capacitor of the second power module is slowly charged. After the voltage of the second power module stabilizes, the control mode of the second power module is set to fixed phase shift control, the second power module is unlocked, and the sign and magnitude of the phase shift angle are adjusted to control the direction and magnitude of the AC current, further adjusting the direction and magnitude of the reactive power.

[0029] In a fourth aspect of the present invention, a method for testing cascaded energy storage power modules is proposed, which is performed based on a cascaded energy storage power module testing system.

[0030] When conducting reactive power drag testing, the method includes:

[0031] The DC-side capacitor of the first power module is charged by a DC source. After charging to the rated state, the third control logic of the control chassis is executed, wherein the control mode of the first power module is a fixed-regulation mode. The first power module is unlocked, and the regulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the required value, and the DC-side capacitor of the second power module is slowly charged. After the voltage of the second power module stabilizes, the control mode of the second power module is set to constant voltage constant reactive power control. The constant voltage control loop adjusts the voltage of the second power module through active power and adjusts the constant reactive current loop through reactive power.

[0032] The cascaded energy storage power module drag-and-drop testing system and method proposed in this invention have at least the following technical advantages compared with the prior art:

[0033] We provide a low-cost, reliable, and universal cascaded energy storage power module test platform; it can test the power modules, filter modules, and batteries of energy storage converters. The active / reactive power test topology is easy to wire and switch between, forming a closed loop during testing, resulting in low overall energy consumption.

[0034] It provides a complete active / reactive power module test solution for energy storage converters. By controlling the control chassis to adjust the converter's operating mode and output voltage and current, it can simulate the charging and discharging and reactive / active output of the entire energy storage converter.

[0035] The safety of energy storage converters largely depends on the reliability of the batteries. In practical engineering, it is usually required that the harmonics of the current flowing into the battery should not be too large. Compared with traditional energy storage converter test platforms, this platform can test the battery charging and discharging process and the battery background. The addition of the filter module can test whether the harmonics flowing into the battery meet the engineering requirements, making it more practical. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the active power drag test architecture of a cascaded energy storage power module drag test system according to an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of the architecture for reactive power drag testing of a cascaded energy storage power module drag testing system according to an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of the architecture for reactive power drag testing of a cascaded energy storage power module drag testing system according to another embodiment of the present invention.

[0040] Figure 4 This is a logical schematic diagram of an embodiment of the active power drag test of the present invention.

[0041] Figure 5 This is a logical schematic diagram of a reactive power drag test according to an embodiment of the present invention.

[0042] Figure 6 This is a logic diagram of a reactive power drag test according to another embodiment of the present invention.

[0043] Figure 7 This is a schematic diagram of the architecture of an energy storage PCS test platform proposed in the existing technology.

[0044] Figure 8 This is a schematic diagram of the architecture of another energy storage PCS test platform proposed by existing technology. Detailed Implementation

[0045] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0046] Those skilled in the art will recognize that embodiments of the present invention can be implemented as a system, apparatus, device, method, or computer program product. Therefore, this disclosure can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0047] According to an embodiment of the present invention, a test system and method for cascaded energy storage power modules are proposed, relating to the field of power testing technology.

[0048] In the embodiments of the present invention, the following terms need to be explained:

[0049] Energy storage device: A Power Conversion System (PCS) is a device used to store grid energy in batteries or to transmit energy from batteries to the grid. It controls the charging and discharging process of batteries, performs AC / DC conversion, and can directly supply power to AC loads in the absence of a grid.

[0050] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0051] The cascaded energy storage power module counter-driving test system proposed in this invention is used to perform active power counter-driving and reactive power counter-driving tests on the energy storage power modules of high-power cascaded energy storage devices. It includes: a first power module, a second power module, a first filter module, a second filter module, a first battery cluster, a second battery cluster, a control chassis, and a counter-driving inductor.

[0052] For details, please refer to Figure 1 When using the cascaded energy storage power module to conduct a towing test, the active power test mode architecture is as follows:

[0053] The DC side of the first power module is connected to the first battery cluster via the first filter module; the DC side of the second power module is connected to the second battery cluster via the second filter module; the AC side of the first power module is connected to the AC side of the second power module via a pull-out inductor; the control chassis is connected to the control boards of the first and second power modules to control the charging and discharging state of the batteries and adjust the power.

[0054] refer to Figure 2 The architecture of the reactive power test mode is as follows:

[0055] The DC side of the first power module is connected to a DC source, and the AC side is connected to the AC side of the second power module through a pull-out inductor. The control chassis is connected to the control boards of the first and second power modules. By adjusting the phase angle and amplitude of the AC output voltage and current, reactive power can circulate between the converters of the two power modules, forming a closed loop.

[0056] In another embodiment, reference Figure 3 Another architecture for reactive power testing mode is:

[0057] The DC side of the first power module is connected to one end of the first filter module, and the other end of the first filter module is connected to a DC source. The AC side of the first power module is connected to the AC side of the second power module through a pull-out inductor. The DC side of the second power module is connected to one end of the second filter module (wherein, the other end of the second filter module is in an open circuit state). The control chassis is connected to the control boards of the first power module and the second power module. By adjusting the phase angle and amplitude of the AC side output voltage and current, reactive power can circulate between the converters of the two power modules to form a closed loop.

[0058] Figure 3 Compared to Figure 2 The architecture was modified to include a filtering module for observing the filtering effect of the filter.

[0059] Specifically, in Figure 1 and Figure 3 In the diagram, position 1 and position 2 represent two different measurement points. The voltage measured at position 1 fluctuates, and this fluctuation is filtered out by the filtering module. The voltage measured at position 2 is smooth and stable. The filtering effect can be verified by comparing the voltage waveforms at the two locations.

[0060] In one specific embodiment, the DC source is obtained by rectifying a three-phase AC power grid connected to a three-phase bridge converter; wherein, the devices used in the three-phase bridge converter are thyristors or fully controlled power electronic devices.

[0061] The first and second power modules are AC / DC converters used to control the charging and discharging process of the battery and to perform AC / DC conversion.

[0062] The first and second filtering modules are used to filter the current flowing into the battery branch, and respectively perform second harmonic filtering of the voltage, high-frequency current filtering of the switching frequency, and low-frequency oscillation suppression on the DC side of the first and second power modules.

[0063] The control box is powered by AC mains (e.g., 220V AC) and is connected to the control boards of the first power module and the second power module via optical fiber.

[0064] The first and second battery clusters achieve energy transfer within the battery clusters by charging and discharging the batteries.

[0065] This invention enables the control of power module voltage / power and the selection of active / reactive power paired test modes by setting the mode of the control chassis, thereby realizing multiple test modes. The control modes of the control chassis for the two sets of power modules include at least: DC voltage control, open-loop fixed-mode inverter mode, open-loop phase angle control mode, closed-loop active power control mode, and closed-loop reactive power control mode. In practical application scenarios, a combination of one or more of the above control methods can be used.

[0066] The cascaded energy storage power module drag-and-drop test system proposed in this invention can perform multiple types of tests, has good practicality, can effectively control the cost of drag-and-drop test of power modules, and at the same time ensure the reliability of drag-and-drop test results, and reproduce the operating conditions of power modules to the greatest extent.

[0067] To provide a clearer explanation of the above-mentioned cascaded energy storage power module test system, a detailed explanation is provided below in conjunction with specific control methods.

[0068] This invention can realize active power-to-reactive power-to-reactive power-to-reactive power module testing, and the specific method is as follows:

[0069] I. The method for testing active drag is as follows:

[0070] right Figure 1 When controlling the cascaded energy storage power module's drag-and-drop test system, both batteries need to have initial charge before the test; for example, the SOC (State of Charge) is usually around 50%, and the battery voltages are basically equal (the voltage difference is within a set threshold range). A charging soft-start circuit is provided at the output terminals of both the first and second battery clusters. At the start of drag-and-drop, contactors QF1 and QF2 are closed through the first and second battery clusters, charging the DC-side capacitors of the first and second power modules and the first and second filter modules through soft-start resistors Ry1 and Ry2. When the charge reaches near steady state, contactors KM1 and KM2 at the output terminals of the first and second battery clusters are closed, making the DC-side capacitor voltages of the first and second power modules consistent with the output voltages of the first and second battery clusters.

[0071] During the active power supply test, the control chassis settings logic is as follows: Figure 4 As shown, the first power module is controlled in a fixed-mode operation, controlling the AC output voltage to a constant value. Ta is obtained using a fixed-mode operation, while Tb is obtained using a closed-loop active current control mode. The second power module is controlled in an AC current control mode. Given the magnitudes of the active and reactive current commands, the phase angle and amplitude of the modulation wave in the second power module can be controlled through the AC current loop, adjusting the magnitude and direction of the AC current, thereby regulating the magnitude and direction of the active and reactive power.

[0072] During the test, the active power flowed from one end to the other in the form of battery energy transfer, and there was no significant loss of active power overall.

[0073] II. One method for reactive power drag testing is as follows:

[0074] right Figure 2 or Figure 3 When controlling the cascaded energy storage power module test system, the DC-side capacitor of the first power module is charged via a DC source before the test; after charging to the rated state, the control chassis is set as follows: Figure 5 The logic shown indicates that the first power module control mode is a fixed modulation mode. Here, Ta is the modulation waveform input for the first power module, and Tb is the modulation waveform input for the second power module. First, the first power module is unlocked, and its modulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the desired value. During this process, the DC-side capacitor of the second power module charges slowly. Once the voltage of the second power module stabilizes, the control mode for the second power module is set to fixed phase shift control. The second power module is unlocked, and the sign and magnitude of the phase shift angle are adjusted to control the direction and magnitude of the AC current, thereby adjusting the direction and magnitude of the reactive power.

[0075] III. Another method for reactive power drag testing is:

[0076] right Figure 2 or Figure 3 When controlling the cascaded energy storage power module test system shown, the DC-side capacitor of the first power module is charged via a DC source before the test; after charging to the rated state, the settings at the control chassis are as follows: Figure 6 The logic shown indicates that the first power module control mode is a constant modulation mode. Here, Ta is the modulation waveform input for the first power module, and Tb is the modulation waveform input for the second power module. First, the first power module is unlocked, and its modulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the desired value. During this process, the DC capacitor of the second power module charges slowly. Once the voltage of the second power module stabilizes, the control mode is set to constant voltage constant reactive power control. The constant voltage control loop adjusts the voltage of the second power module through active power and adjusts the constant reactive current loop through reactive power.

[0077] In summary, adopting Figure 1 Hardware (power module + filter module + battery) and Figure 4 The software settings (active power test mode) can achieve active power drag.

[0078] use Figure 2 Hardware (power module + filter module) or Figure 3 The hardware (power module), and Figure 5 or Figure 6 The software settings (reactive power test mode) allow for reactive power-assisted load reduction. That is, Figure 5 and Figure 6 All reactive power test modes are applicable Figure 2 and Figure 3 The drag testing system.

[0079] The active power test mode / reactive power test mode is achieved by adjusting the control method of the two power modules.

[0080] The cascaded energy storage power module drag-and-drop testing system and method proposed in this invention have at least the following technical advantages compared with the prior art:

[0081] We provide a low-cost, reliable, and universal cascaded energy storage power module test platform; it can test the power modules, filter modules, and batteries of energy storage converters. The active / reactive power test topology is easy to wire and switch between, forming a closed loop during testing, resulting in low overall energy consumption.

[0082] It provides a complete active / reactive power module test solution for energy storage converters. By controlling the control chassis to adjust the converter's operating mode and output voltage and current, it can simulate the charging and discharging and reactive / active output of the entire energy storage converter.

[0083] The safety of energy storage converters largely depends on the reliability of the batteries. In practical engineering, it is usually required that the harmonics of the current flowing into the battery should not be too large. Compared with traditional energy storage converter test platforms, this platform can test the battery charging and discharging process and the battery background. The addition of the filter module can test whether the harmonics flowing into the battery meet the engineering requirements, making it more practical.

[0084] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] This invention is described with reference to flowchart illustrations and / or block diagrams of methods and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0086] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0087] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0088] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for testing the drag-and-drop capability of cascaded energy storage power modules, characterized in that, This method is implemented based on a drag-and-drop test system for cascaded energy storage power modules; The cascaded energy storage power module test system includes: a first power module, a second power module, a first filter module, a second filter module, a first battery cluster, a second battery cluster, a control chassis, and a cascaded inductor; When conducting towing tests using the towing test system of this cascaded energy storage power module, the architecture of the active power test mode is as follows: The DC side of the first power module is connected to the first battery cluster via the first filter module; the DC side of the second power module is connected to the second battery cluster via the second filter module; the AC side of the first power module is connected to the AC side of the second power module via a pull-out inductor; the control chassis is connected to the control boards of the first and second power modules to control the charging and discharging state of the batteries and adjust the power. The first architecture of the reactive power testing mode is as follows: The first power module's DC side is connected to a DC source, and its AC side is connected to the second power module's AC side via a pull-out inductor. The control chassis is connected to the control boards of the first and second power modules. By adjusting the phase angle and amplitude of the AC output voltage and current, reactive power is circulated between the converters of the two power modules, forming a closed loop. The second architecture of the reactive power testing mode is as follows: The DC side of the first power module is connected to one end of the first filter module, and the other end of the first filter module is connected to a DC source; the AC side of the first power module is connected to the AC side of the second power module through a pull-out inductor; the DC side of the second power module is connected to one end of the second filter module; the control chassis is connected to the control boards of the first power module and the second power module, and by adjusting the phase angle and amplitude of the AC side output voltage and current, reactive power can circulate between the converters of the two power modules to form a closed loop; When conducting reactive power drag testing, the method includes: The DC-side capacitor of the first power module is charged by a DC source. After charging to the rated state, the second control logic of the control chassis is executed, wherein the control mode of the first power module is a fixed modulation mode. The first power module is unlocked, and the modulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the required value, while the DC-side capacitor of the second power module is slowly charged. After the voltage of the second power module stabilizes, the control mode of the second power module is set to fixed phase shift control, the second power module is unlocked, and the sign and magnitude of the phase shift angle are adjusted to control the direction and magnitude of the AC current, further adjusting the direction and magnitude of the reactive power.

2. The method according to claim 1, characterized in that, The DC power source is obtained by rectifying a three-phase AC power grid connected to a three-phase bridge converter; the three-phase bridge converter uses thyristors or fully controlled power electronic devices.

3. The method according to claim 1, characterized in that, The first and second power modules are AC / DC converters used to control the charging and discharging process of the battery and to perform AC / DC conversion.

4. According to the method of claim 1, the first filtering module and the second filtering module are used to filter the current flowing into the battery branch, and respectively perform second harmonic filtering of voltage, high-frequency current filtering of switching frequency, and low-frequency oscillation suppression on the DC side of the first power module and the second power module.

5. The method according to claim 1, wherein the control chassis is powered by AC power grid and is connected to the control boards of the first power module and the second power module via optical fiber.

6. The method according to claim 1, wherein the first battery cluster and the second battery cluster achieve energy transfer within the battery cluster by charging and discharging the batteries.

7. The method according to claim 1, characterized in that, The first architecture based on reactive power testing mode includes the following method when performing active power drag testing: The initial charge levels of the batteries in the first and second battery clusters are adjusted to ensure that the voltage difference between the batteries is within a set threshold range. At the start of the charging process, the charging soft-start circuits at the output terminals of the first and second battery clusters are controlled, and the contactors in the charging soft-start circuits are closed. The first and second battery clusters charge the DC-side capacitors of the first and second power modules and the DC-side capacitors of the first and second filter modules respectively through the soft-start resistors in the charging soft-start circuits. When the charging reaches near steady state, the contactors at the output terminals of the first and second battery clusters are closed, making the DC-side capacitor voltages of the first and second power modules consistent with the output voltages of the first and second battery clusters. During the active power supply test, the first control logic of the control box is set. The first power module control mode is a fixed-mode mode, which controls the AC output voltage to a fixed value. The second power module control mode is AC current control, which gives the magnitude of active and reactive current commands. Through the AC current loop, the phase angle and amplitude of the modulation wave of the second power module are controlled to adjust the magnitude and direction of the AC current, thereby further adjusting the magnitude and direction of active and reactive power.

8. A method for testing the drag-and-drop capability of a cascaded energy storage power module, characterized in that, This method is implemented based on a drag-and-drop test system for cascaded energy storage power modules; The cascaded energy storage power module test system includes: a first power module, a second power module, a first filter module, a second filter module, a first battery cluster, a second battery cluster, a control chassis, and a cascaded inductor; When conducting towing tests using the towing test system of this cascaded energy storage power module, the architecture of the active power test mode is as follows: The DC side of the first power module is connected to the first battery cluster via the first filter module; the DC side of the second power module is connected to the second battery cluster via the second filter module; the AC side of the first power module is connected to the AC side of the second power module via a pull-out inductor; the control chassis is connected to the control boards of the first and second power modules to control the charging and discharging state of the batteries and adjust the power. The first architecture of the reactive power testing mode is as follows: The first power module's DC side is connected to a DC source, and its AC side is connected to the second power module's AC side via a pull-out inductor. The control chassis is connected to the control boards of the first and second power modules. By adjusting the phase angle and amplitude of the AC output voltage and current, reactive power is circulated between the converters of the two power modules, forming a closed loop. The second architecture of the reactive power testing mode is as follows: The DC side of the first power module is connected to one end of the first filter module, and the other end of the first filter module is connected to a DC source; the AC side of the first power module is connected to the AC side of the second power module through a pull-out inductor; the DC side of the second power module is connected to one end of the second filter module; the control chassis is connected to the control boards of the first power module and the second power module, and by adjusting the phase angle and amplitude of the AC side output voltage and current, reactive power can circulate between the converters of the two power modules to form a closed loop; When conducting reactive power drag testing, the method includes: The DC-side capacitor of the first power module is charged by a DC source. After charging to the rated state, the third control logic of the control chassis is executed, wherein the control mode of the first power module is a fixed-regulation mode. The first power module is unlocked, and the regulation is gradually increased from zero to the set value, controlling the AC output voltage to gradually increase to the required value, and the DC-side capacitor of the second power module is slowly charged. After the voltage of the second power module stabilizes, the control mode of the second power module is set to constant voltage constant reactive power control. The constant voltage control loop adjusts the voltage of the second power module through active power and adjusts the constant reactive current loop through reactive power.

9. The method according to claim 8, characterized in that, The first architecture based on reactive power testing mode includes the following method when performing active power drag testing: The initial charge levels of the batteries in the first and second battery clusters are adjusted to ensure that the voltage difference between the batteries is within a set threshold range. At the start of the charging process, the charging soft-start circuits at the output terminals of the first and second battery clusters are controlled, and the contactors in the charging soft-start circuits are closed. The first and second battery clusters charge the DC-side capacitors of the first and second power modules and the DC-side capacitors of the first and second filter modules respectively through the soft-start resistors in the charging soft-start circuits. When the charging reaches near steady state, the contactors at the output terminals of the first and second battery clusters are closed, making the DC-side capacitor voltages of the first and second power modules consistent with the output voltages of the first and second battery clusters. During the active power supply test, the first control logic of the control box is set. The first power module control mode is a fixed-mode mode, which controls the AC output voltage to a fixed value. The second power module control mode is AC current control, which gives the magnitude of active and reactive current commands. Through the AC current loop, the phase angle and amplitude of the modulation wave of the second power module are controlled to adjust the magnitude and direction of the AC current, thereby further adjusting the magnitude and direction of active and reactive power.

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