Dragging test method of charge and discharge test system

Abstract

The invention discloses a twin trawling test method of a charging and discharging test system. The twin trawling test method is based on the charging and discharging test system composed of a direct current bus, an AC / DC unit connected with the direct current bus and three DC / DC units. When the system is in a twin trawling test, any two of the three DC / DC units are selected as a test unit and are connected with the test container, and the remaining DC / DC unit is used as a voltage stabilization unit and is connected with the accompanying test container to work in a voltage stabilization mode, and the voltage of the bus is maintained to be constant together with the AC / DC unit. The used AC / DC unit is small in specification, the manufacturing cost and the use cost of equipment are greatly reduced, meanwhile, the requirement for the power grid capacity of the charging and discharging test system topology is small, and a power load used for consuming feed is not needed, so that the earlier-stage investment of the capacity test of the energy storage container can be effectively reduced, and the energy storage container capacity test efficiency is improved. In addition, the system can be combined with an improved test rhythm, and the test time is effectively shortened.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage container capacity testing, and in particular relates to a towing test method of a charge and discharge test system. Background Art

[0002] When conducting a capacity towing test on an existing energy storage container, the test process is generally as follows.

[0003] 1. Adjust SOC: The initial SOC of the energy storage container is generally around 30%. The SOC of one energy storage container needs to be adjusted to 0, and the SOC of the other energy storage container needs to be adjusted to 100%.

[0004] 2. Full charge / full discharge capacity test: A full charge test (usually 0.25P or 0.5P) is performed on the container whose SOC is 0 at the end of the first step until its SOC increases to 100% (charge capacity test). At the same time, a full discharge test is performed on the container whose SOC is 100% at the end of the first step until its SOC decreases to 0 (discharge capacity test).

[0005] 3. For containers with an SOC of 100% at the end of step 2, perform a full discharge test until the SOC drops to 0 (discharge capacity test). Simultaneously, for containers with an SOC of 0 at the end of step 2, perform a full charge test until the SOC increases to 100% (charge capacity test).

[0006] 4. Adjust the SOC to the shipping status: Adjust the SOC of the two containers tested in step 3 to approximately 30%.

[0007] During the above test process, in order to reduce system loss, the test rhythm will be adjusted manually so that the system works in a parallel state as much as possible (one group is charging and the other group is discharging).

[0008] The actual test cycle is shown in the following table (taking 0.5P, i.e. 0.5 times rated power test, as an example).

[0009] .

[0010] From the above test rhythm, we can see that during most of the time (1, 3, 4, 5, 6, 7, 8), container 1# and container 2# are in a towing state, and the AC energy is low. The energy flow is as follows: Figure 1 As shown; in step 2, only container 1# is working (charging), and the AC side bears the test power (0.25P). Therefore, the system AC / DC and front-end power distribution must be designed according to the test power. At this time, the energy flow is as follows Figure 2 As shown; in step 9, only container 1# is working (discharging). To prevent energy from feeding back to the grid, an energy-consuming resistor needs to be put in. The energy flow is as follows Figure 3As shown in the figure, container 2# has two waiting times (steps 2 and 9), which prolongs the entire test cycle.

[0011] In summary, existing testing solutions have the following problems: the system's AC / DC and power distribution need to be designed according to the test power, which results in significant waste and low utilization. To solve the energy feed problem, energy-consuming resistors need to be configured, which requires a large initial investment and results in energy waste. To meet the test cycle, the test time is long. Summary of the Invention

[0012] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a towing test method for an energy storage container charging and discharging test system.

[0013] The technical solution adopted by the present invention to solve its technical problem is: a towing test method for a charging and discharging test system, which is based on a charging and discharging test system composed of a DC bus, an AC / DC unit connected to the DC bus, and three DC / DC units; comprising the following steps: the high-voltage end and the low-voltage end of the DC / DC unit are connected to the DC bus and the energy storage container respectively; two DC / DC units are selected as test units (1# test unit and 2# test unit), and the energy storage containers connected to their low-voltage ends are used as the 1# tested container and the 2# tested container, and the 1# tested container and the 2# tested container are respectively tested according to the set test process. The output current, voltage and / or power of the 2# tested container are tested. The remaining DC / DC unit serves as a voltage stabilizing unit, and the energy storage container connected to its low-voltage end serves as a companion test container. Both the DC / DC unit and the AC / DC unit operate in voltage stabilizing mode, and the control target is to maintain a constant DC bus voltage. One test unit is selected, and the energy storage container connected to its low-voltage end is first tested for charging capacity and then for discharging capacity. The remaining energy storage containers and the companion test containers are alternately tested in a process of first discharging capacity and then charging capacity, or first charging capacity and then discharging capacity.

[0014] Furthermore, the 1# tested container, the 2# tested container and the accompanying test container are subjected to charge and discharge tests according to the following steps:

[0015] S1: Charge the 1# container under test connected to the 1# test unit to 30% to 70%, and the accompanying test container connected to the voltage stabilizing unit will be powered and discharged to 70% to 30%. At this time, the 1# container under test connected to the 1# test unit will operate at a constant voltage after the package is changed;

[0016] In S2, the 1# tested container is charged to 70% to 100%, and the 2# tested container connected to the 1# test unit is powered by the 2# tested container, which is discharged from 30% to 0, and the SOC of the accompanying test container is maintained at 30%;

[0017] In S3, the 1# container under test is placed at rest after charging and the 2# container under test is placed at rest after discharging, and the SOC of the accompanying container is maintained at 30%;

[0018] S4, the 1# tested container is discharged from 100% to 0, and the 2# tested container is powered, which is charged from 0% to 100%. The SOC of the accompanying test container is maintained at 30%;

[0019] S5: The discharged container 1# is left at rest, the charged container 2# is left at rest, and the SOC of the accompanying container is kept at 30%;

[0020] S6: 1# tested container is charged from 0 to 100%, and powered by 2# tested container, which is discharged from 100% to 0, and the SOC of the accompanying test container is maintained at 30%;

[0021] S7: The 1# container under test is at rest after charging and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%.

[0022] In S8, the 1# tested container is discharged from 100% to 70%, supplying power to the 2# tested container, which is charged from 0 to 30% to complete the test. The SOC of the accompanying container is maintained at 30%;

[0023] S9: The 1# tested container is discharged 70% to 30% to complete the test. The 2# tested container is operated at a constant pressure after the package is changed. The accompanying test container is charged 30% to 70% by the 1# tested container.

[0024] S10, after the tested container 1# is replaced with a new one, it will be operated at a constant pressure. The tested container 2# will be discharged from 30% to 0%, and the accompanying container will be charged from 70% to 100% by the tested container 2#.

[0025] S11: The SOC of the tested container #1 is kept at 30%, the discharged tested container #2 is kept at rest, and the charged companion container is kept at rest;

[0026] In step S12, the SOC of the tested container #1 is kept at 30%, the tested container #2 is powered by the accompanying container, which is charged from 70% to 100%, and the accompanying container is discharged from 100% to 0%;

[0027] In step S13, the SOC of the tested container #1 is kept at 30%, the tested container #2, which has been fully charged, is kept at rest, and the accompanying tested container, which has been fully discharged, is kept at rest;

[0028] In step S14, the SOC of the tested container #1 is kept at 30%, the tested container #2 is discharged from 100% to 0%, and the accompanying container is charged from 0% to 100%;

[0029] In step S15, the SOC of the tested container #1 is kept at 30%, the tested container #2, which has been discharged, is kept at rest, and the accompanying tested container, which has been charged, is kept at rest;

[0030] In S16, the SOC of the tested container #1 is maintained at 30%, and the tested container #2 is powered by the accompanying container. The test is completed by charging it from 0% to 30%, and the accompanying container is discharged from 100% to 70%;

[0031] S17: 1# tested container is charged 30% to 70%, powered by 2# tested container, which is discharged 70% to 30%. 2# tested container operates at constant voltage after the package is changed;

[0032] S18, 1# tested container is charged 70-100%, powered by 2# tested container, which is discharged 30%-0, and the test container is operated at constant voltage after the package is changed;

[0033] S19: The 1# container under test is at rest after charging, and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%.

[0034] In S20, the 1# tested container is discharged from 100% to 0, supplying power to the 2# tested container, which is charged from 0 to 100% to complete the test. The SOC of the accompanying container is maintained at 30%;

[0035] S21: The discharged container 1# is left at rest, the charged container 2# is left at rest, and the SOC of the accompanying container is kept at 30%;

[0036] In S22, the 1# tested container is charged from 0 to 100%, and the 2# tested container is powered, which is discharged from 100% to 0, and the SOC of the accompanying test container is maintained at 30%;

[0037] S23: The 1# container under test is at rest after charging, and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%.

[0038] In S24, the 1# tested container is discharged from 100% to 70%, supplying power to the 2# tested container, which is charged from 0% to 30% to complete the test. The SOC of the accompanying container is maintained at 30%;

[0039] S25: The 1# tested container is discharged 70% to 30% to complete the test. The 2# tested container is operated at a constant pressure after the package is changed. The accompanying test container is charged 30% to 70% by the 1# tested container.

[0040] S26, after the package of the 1# tested container is replaced, constant pressure operation is carried out, and then the next cycle is entered according to step S1. The 2# tested container is discharged from 30% to 0, and then the next cycle is entered according to step S1. The accompanying test container is charged from 70% to 100% by the 2# tested container, and then the next cycle is entered according to step S1.

[0041] Furthermore, the charge and discharge test system has an output voltage of 1650V, an output current of 3300A, and a test power of 3.3MW.

[0042] The beneficial effects of the present invention are:

[0043] The test cycle involved in the present invention utilizes an additional voltage stabilization unit compared to the original solution. During the intervals of the voltage stabilization process, the SOC of the energy storage container can be adjusted. This shortens the test cycle of first discharging capacity test and then charging capacity test.

[0044] The present invention adjusts the structure of the existing charge and discharge test system that only uses AC / DC units for voltage stabilization, adds a voltage-stabilizing DC / DC unit as a supplementary power supply for the DC microgrid, and cleverly uses the energy storage container to be tested as part of the system.

[0045] The voltage-stabilizing AC / DC unit used in this invention is small in size and requires a low grid capacity, eliminating the need for a dedicated supporting energy storage container. This significantly reduces the manufacturing and operating costs of the equipment, effectively lowering the initial investment required for testing large-capacity energy storage containers. Furthermore, this system can be combined with an improved test cycle to effectively shorten testing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The energy flow direction when two test stations are dragged against each other in the existing test scheme;

[0047] Figure 2 For the existing test scheme, only the energy flow when the charging station is working;

[0048] Figure 3 For the existing test scheme, only the energy flow when the discharge station is working;

[0049] Figure 4 The energy flow direction when two test stations are dragged against each other in the test method of the present invention;

[0050] Figure 5 The energy flow direction when the test method of the present invention is only discharged;

[0051] Figure 6 The energy flow direction when the test method of the present invention is only charged;

[0052] Figure 7 Schematic diagram for comparing the two testing methods of the present invention. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0054] Reference Figure 4 、 Figure 5 and Figure 6 As shown, the present invention is based on a charging and discharging test system consisting of a DC bus, a voltage-stabilizing AC / DC unit connected to the DC bus, and three voltage-stabilizing DC / DC units of the same specifications. The system of the present invention is a system for testing the power capacity of containers with an output voltage of 1650V, an output current of 3300A, and a test power of 3.3MW (0.5P).

[0055] The present invention is designed so that the DC bus voltage must be greater than the output voltage, and is designed to be 1700V. Due to the high DC bus voltage, the voltage-stabilizing DC / DC unit adopts a three-level mode, that is, two bus sections are connected in series to bear a voltage of 1700V, and the voltage of each bus section is 850V. The three voltage-stabilizing DC / DC units are consistent in topology, wherein the voltage-stabilizing AC / DC unit and the voltage-stabilizing DC / DC unit constitute a dual power supply system, and anti-circulation measures can be adopted to complete the capacity allocation of the two power supplies according to the actual test situation, and anti-circulation measures are adopted. On the one hand, the specifications of components such as AC / DC and front-end transformers in the original topology can be greatly reduced, which can greatly reduce the equipment cost. On the other hand, the requirements for the power distribution capacity of the power grid can be greatly reduced. No additional accompanying test power supply or resistive load is required, the use cost is low, the operation rhythm is compact, and the test efficiency is high. Due to the peak-shaving and valley-filling effect of the voltage-stabilizing unit and the accompanying test container, the power flowing through the AC / DC side can be greatly reduced, and the power distribution capacity of the AC side can be reduced. In addition, since this topology can avoid energy feeding to the grid, it can be omitted. Figure 1 The configuration of medium energy consumption resistors saves initial investment and electricity costs.

[0056] The voltage-stabilizing DC / DC unit and the test DC / DC unit of the present invention have identical specifications and are interchangeable. The voltage-stabilizing DC / DC unit and the test DC / DC unit alternately regulate and test the voltage, and the energy storage containers under test alternately accompany and test the units, enabling reuse of all DC / DC units and energy storage containers. Leveraging the advantages of the novel topology of the test system of the present invention, the test cycle can be adjusted, eliminating the waiting time inherent in the original test cycle.

[0057] During the system towing test, three energy storage containers and three voltage-stabilizing DC / DC units are connected respectively.

[0058] In this embodiment, the AC / DC capacity is set: in the present invention, the AC / DC side only needs to provide the power consumed by the system during the towing test. Calculated based on the equipment efficiency of the DC / DC side being 95%. The power absorbed from the AC side during charging conditions is 3.3M / 0.95=3.47MW; the power released to the AC side during discharging conditions is 3.3*0.95=3.14MW. Therefore, when the towing test is performed, the total power on the AC side is 3.47-3.14=0.33MW. Taking into account the margin, it can be designed as 0.5MW.

[0059] That is, according to the solution in the background technology, the AC / DC and front-end distribution capacity needs to be designed at 3.47MW (3.3 / 0.95), while in the new solution provided by this patent application, the two can be designed at 0.5MW, which is only equivalent to 14.4% of the capacity of the original solution.

[0060] The test method of the present invention selects any one of the three DC / DC units as a voltage stabilizing unit to connect to the energy storage container under test. The unit works in voltage stabilizing mode and forms a dual power supply DC system with the AC / DC unit. The voltage stabilizing unit and the container under test bear the intermittent peak power during the towing test of the other two test units, such as Figure 5 、 Figure 6 shown.

[0061] The steps for system towing test are as follows.

[0062] S1: Charge the 1# container under test connected to the 1# test unit to 30% to 70%. The accompanying test container connected to the voltage stabilizing unit is powered and discharged to 70% to 30%. At this time, the 1# container under test connected to the 1# test unit is operated at a constant voltage after the package is replaced. This step takes 0.8h.

[0063] S2: 1# tested container is charged to 70% to 100%, and 2# tested container connected to 1# test unit is powered and discharged to 30% to 0, while the SOC of the accompanying test container is maintained at 30%. This step takes 0.6h.

[0064] S3: The charged container #1 is left to rest, the discharged container #2 is left to rest, and the SOC of the accompanying container is maintained at 30%. This step takes 0.5 h.

[0065] During this test step, both container #1 and container #2 were in a static state, with no system consumption. The voltage-stabilized AC / DC unit worked in conjunction with the three voltage-stabilized DC / DC units to replenish the energy consumed by the companion containers during the initial test (for example, to achieve a SOC of 30%). In subsequent test steps, the system control logic remained the same as above.

[0066] S4: Container 1 is discharged from 100% to 0, supplying power to container 2, which is charged from 0% to 100%. The SOC of the accompanying container is maintained at 30%. This step takes 2 hours.

[0067] S5: The discharged container #1 is left to rest, the charged container #2 is left to rest, and the SOC of the accompanying container is maintained at 30%. This step takes 0.5 h.

[0068] S6: Container 1 is charged from 0 to 100%, and container 2 is supplied with power, which is discharged from 100% to 0, while the SOC of the accompanying container is maintained at 30%. This step takes 2 hours.

[0069] S7: The charged container #1 is left to rest, and the discharged container #2 is left to rest. The SOC of the accompanying container is maintained at 30%. This step takes 0.5 h.

[0070] In step S8, the 1# container under test is discharged from 100% to 70%, supplying power to the 2# container under test, which is charged from 0% to 30% to complete the test. The SOC of the accompanying container is maintained at 30%. This step takes 0.6 hours.

[0071] S9: The 1# tested container is discharged to 70% to 30% to complete the test. The 2# tested container is operated at a constant pressure after the package is changed. The accompanying test container is charged 30% to 70% by the 1# tested container. This step takes 0.8 seconds.

[0072] S10, after the package of the 1# tested container is replaced, it operates at a constant pressure, the 2# tested container is discharged from 30% to 0, and the accompanying test container is charged from 70% to 100% by the 2# tested container; this step takes 0.6 hours.

[0073] S11, the SOC of the 1# tested container is maintained at 30%, the 2# tested container that has completed discharge is placed at rest, and the accompanying test container that has completed charging is placed at rest; this step takes 0.5 hours.

[0074] S12, the SOC of the tested container #1 is maintained at 30%, the tested container #2 is powered by the accompanying container, which is charged from 70% to 100%, and the accompanying container is discharged from 100% to 0; this step takes 2 hours.

[0075] S13, the SOC of the tested container #1 is maintained at 30%, the tested container #2, which has been charged, is left to stand, and the accompanying tested container, which has been discharged, is left to stand. This step takes 0.5 h.

[0076] In step S14, the SOC of the tested container #1 is maintained at 30%, the tested container #2 is discharged from 100% to 0%, and the accompanying container is charged from 0% to 100%. This step takes 2 hours.

[0077] S15, the SOC of the 1# tested container is maintained at 30%, the 2# tested container that has completed discharge is placed at rest, and the accompanying test container that has completed charging is placed at rest; this step takes 0.5 h.

[0078] S16: The SOC of the tested container #1 is maintained at 30%. The tested container #2 is powered by the accompanying container and is charged from 0% to 30% to complete the test. The accompanying container is discharged from 100% to 70%. This step takes 0.6 hours.

[0079] S17: Container 1 is charged to 30% to 70%, and then powered by container 2, which is discharged to 70% to 30% to complete the test. Container 2 then switches to a constant voltage operation after the package is replaced. This step takes 0.8 hours.

[0080] S18, the 1# tested container is charged to 70-100%, and the power is supplied by the 2# tested container, which is discharged to 30%-0. After the test container is replaced with a bag, it operates at a constant voltage. This step takes 0.6 hours.

[0081] S19, the 1# tested container after charging is allowed to stand still, and the 2# tested container after discharging is allowed to stand still, and the SOC of the accompanying test container is maintained at 30%; this step takes 0.5 hours.

[0082] In step S20, the 1# container under test is discharged from 100% to 0, supplying power to the 22# container under test, which is charged from 0% to 100% to complete the test. The SOC of the accompanying container is maintained at 30%. This step takes 2 hours.

[0083] S21, the discharged container #1 is left to rest, the charged container #2 is left to rest, and the SOC of the accompanying container is maintained at 30%. This step takes 0.5 h.

[0084] S22: Container 1 is charged from 0 to 100%, and container 2 is supplied with power, which is discharged from 100% to 0, while the SOC of the accompanying container is maintained at 30%. This step takes 2 hours.

[0085] S23, the 1# tested container after charging is allowed to stand still, the 2# tested container after discharging is allowed to stand still, and the SOC of the accompanying test container is maintained at 30%; this step takes 0.5 hours.

[0086] In step S24, the 1# container under test is discharged from 100% to 70% to supply power to the 2# container under test, which is charged from 0% to 30% to complete the test. The SOC of the accompanying container is maintained at 30%. This step takes 0.6 hours.

[0087] S25: The 1# tested container is discharged to 70% to 30% to complete the test. The 2# tested container is replaced with a constant pressure and the accompanying test container is charged 30% to 70% by the 1# tested container. This step takes 0.8 hours.

[0088] S26, after the package of the 1# tested container is replaced, constant pressure operation is carried out, and then the next cycle is entered according to step S1. The 2# tested container is discharged from 30% to 0, and then the next cycle is entered according to step S1. The accompanying test container is charged from 70% to 100% by the 2# tested container, and then the next cycle is entered according to step S1. This step takes 0.6 hours.

[0089] The test beat design is shown in the following table.

[0090] .

[0091] From the above test rhythm, it can be seen that: in steps S1 to S9 and S17 to S25, the 1# tested container and the accompanying test container in steps S9 to S17 and 25 to step 1 are subjected to a discharge capacity test followed by a charge capacity test; in steps S1 to S26, excluding the constant pressure operation step after the bag change, the 2# tested container is subjected to a charge capacity test followed by a discharge capacity test; in steps S10 to S16, the 1# tested container, the 2# tested container in the constant pressure operation step after the bag change, and the accompanying test container in steps S2 to S8 and S18 to S24 are in the waiting (accompanying) state.

[0092] In the above table, the 2# test unit is selected to perform the process of charging capacity test first and then discharging capacity test. The 1# test unit and the voltage stabilizing unit take turns to perform the process of method 1 and method 2, such as Figure 7 As shown, Method 1 involves discharging the battery from an initial 30% to 0%, then fully charging it to 100% to complete the charge capacity test, then discharging it to 0% to complete the discharge capacity test, and finally charging it back to 30%. Method 2 involves fully charging the battery from an initial 30% to 100%, then discharging it to 0% to complete the discharge capacity test, then fully charging it to 100% to complete the charge capacity test, and finally charging it back to 30%. Methods 1 and 2 combine static stagnation and constant voltage operation after pack replacement. Since the processes of test unit 1 / 9 / 17, etc., shown in the table above, can be overlapped, the process time of first discharging capacity test and then charging capacity test is shortened.

[0093] Steps 1-8 constitute one cycle, which can complete the test of two energy storage containers. The total time for steps 1-8 is 7.5 hours, which saves 1.3 hours compared to 8.8 hours in the background technology, effectively saving test time.

[0094] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some embodiments of its application. A person skilled in the art may make several modifications and improvements without departing from the inventive concept of the present invention, and all of these modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A drag test method for a charge and discharge test system, characterized by: A charge and discharge test system based on a DC bus, an AC / DC unit connected to the DC bus, and three DC / DC units; including the following steps The high-voltage and low-voltage ends of the DC / DC unit are connected to the DC bus and the energy storage container respectively; Select two DC / DC units as test units, and use the energy storage containers connected to their low-voltage ends as the 1# and 2# tested containers. Test the output current, voltage, and / or power of the 1# and 2# tested containers respectively. The remaining DC / DC units serve as voltage stabilization units, and use the energy storage containers connected to their low-voltage ends as companion test containers. Both the DC / DC units and the AC / DC units operate in voltage stabilization mode to keep the DC bus voltage constant. Select a test unit and perform a charging capacity test and then a discharging capacity test on the energy storage container connected to its low-voltage end; The remaining energy storage containers and accompanying test containers take turns to undergo a process of first discharging capacity test and then charging capacity test, or first charging capacity test and then discharging capacity test.

2. The method for dragging a charge and discharge test system according to claim 1, characterized in that: The 1# tested container, 2# tested container and accompanying test container are subjected to charge and discharge tests according to the following steps: S1: Charge the 1# tested container to 30% to 70%, and discharge the power from the accompanying test container connected to the voltage stabilizing unit to 70% to 30%. S2: Container 1# is charged to 70% to 100%, and is powered by container 2#, which is discharged to 30% to 0%. The SOC of the accompanying container is maintained at 30%; In S3, the 1# container under test is placed at rest after charging and the 2# container under test is placed at rest after discharging, and the SOC of the accompanying container is maintained at 30%; S4, the 1# tested container is discharged from 100% to 0, and the 2# tested container is powered, which is charged from 0% to 100%. The SOC of the accompanying test container is maintained at 30%; S5: The discharged container 1# is left at rest, the charged container 2# is left at rest, and the SOC of the accompanying container is kept at 30%; S6: 1# tested container is charged from 0 to 100%, and powered by 2# tested container, which is discharged from 100% to 0, and the SOC of the accompanying test container is maintained at 30%; S7: The 1# container under test is at rest after charging and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%. In S8, the 1# tested container is discharged from 100% to 70%, supplying power to the 2# tested container, which is charged from 0 to 30% to complete the test. The SOC of the accompanying container is maintained at 30%; S9: The 1# tested container is discharged 70% to 30% to complete the test. The 2# tested container is operated at a constant pressure after the package is changed. The accompanying test container is charged 30% to 70% by the 1# tested container. S10, after the tested container 1# is replaced with a new one, it will be operated at a constant pressure. The tested container 2# will be discharged from 30% to 0%, and the accompanying container will be charged from 70% to 100% by the tested container 2#. S11: The SOC of the tested container #1 is kept at 30%, the discharged tested container #2 is kept at rest, and the charged companion container is kept at rest; In step S12, the SOC of the tested container #1 is kept at 30%, the tested container #2 is powered by the accompanying container, which is charged from 70% to 100%, and the accompanying container is discharged from 100% to 0%; In step S13, the SOC of the tested container #1 is kept at 30%, the tested container #2, which has been fully charged, is kept at rest, and the accompanying tested container, which has been fully discharged, is kept at rest; In step S14, the SOC of the tested container #1 is kept at 30%, the tested container #2 is discharged from 100% to 0%, and the accompanying container is charged from 0% to 100%; In step S15, the SOC of the tested container #1 is kept at 30%, the tested container #2, which has been discharged, is kept at rest, and the accompanying tested container, which has been charged, is kept at rest; In S16, the SOC of the tested container #1 is maintained at 30%, and the tested container #2 is powered by the accompanying container. The test is completed by charging it from 0% to 30%, and the accompanying container is discharged from 100% to 70%; S17: 1# tested container is charged 30% to 70%, powered by 2# tested container, which is discharged 70% to 30% to complete the test. 2# tested container is operated at constant voltage after the package is changed; S18, 1# tested container is charged 70-100%, powered by 2# tested container, which is discharged 30%-0, and the test container is operated at constant voltage after the package is changed; S19: The 1# container under test is at rest after charging, and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%. In S20, the 1# tested container is discharged from 100% to 0, supplying power to the 2# tested container, which is charged from 0 to 100% to complete the test. The SOC of the accompanying container is maintained at 30%; S21: The discharged container 1# is left at rest, the charged container 2# is left at rest, and the SOC of the accompanying container is kept at 30%; In S22, the 1# tested container is charged from 0 to 100%, and the 2# tested container is powered, which is discharged from 100% to 0, and the SOC of the accompanying test container is maintained at 30%; S23: The 1# container under test is at rest after charging, and the 2# container under test is at rest after discharging. The SOC of the accompanying container is maintained at 30%. In S24, the 1# tested container is discharged from 100% to 70%, supplying power to the 2# tested container, which is charged from 0% to 30% to complete the test. The SOC of the accompanying container is maintained at 30%; S25: The 1# tested container is discharged 70% to 30% to complete the test. The 2# tested container is operated at a constant pressure after the package is changed. The accompanying test container is charged 30% to 70% by the 1# tested container. S26, after the package of the 1# tested container is replaced, constant pressure operation is carried out, and then the next cycle is entered according to step S1. The 2# tested container is discharged from 30% to 0, and then the next cycle is entered according to step S1. The accompanying test container is charged from 70% to 100% by the 2# tested container, and then the next cycle is entered according to step S1.

3. A drag test method for a charge and discharge test system according to claim 1 or 2, characterized in that: The charge and discharge test system has an output voltage of 1650V, an output current of 3300A, and a test power of 3.3MW.

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