Towel-to-drag test method and system of string PCS system

Abstract

The invention discloses a twin trawling test method and system of a string PCS system, and belongs to the technical field of electrical performance test. The twin trawling test method comprises the following steps: constructing a string type PCS assembly, wherein the string type PCS assembly comprises a first PCS assembly and a second PCS assembly which are connected in series to form a charging and discharging loop; target power is set, so that the first PCS assembly and the second PCS assembly charge and discharge each other; and dynamically distributing the charging and discharging power of each battery module based on the residual electric quantity of each battery module in the first PCS assembly and the second PCS assembly, so that the total charging and discharging power of each battery module is equal to the target power. According to the twin-trawling test method and system of the string PCS system provided by the invention, the cyclic utilization of the charging and discharging energy of the energy storage battery can be realized by constructing a closed-loop test system; the power is distributed according to the residual electric quantity of the battery, the battery is prevented from being damaged due to over-charging or over-discharging, and the test accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical performance testing, and particularly relates to a back-to-back test method and system for a string-type PCS system. Background Art

[0002] With the continuous progress of energy technology and the wide application of renewable energy, the role of energy storage systems in power systems is becoming increasingly important. As the core device of an energy storage system, a power conversion system (PCS) undertakes key functions such as battery charge and discharge management, power regulation, and energy conversion. Therefore, the testing and evaluation of PCS systems have become an important link in the research and development of energy storage technologies.

[0003] In existing PCS testing methods, a fixed charge and discharge power is usually used to test each battery module. In such methods, each battery module is charged and discharged at a preset constant power during the test, without considering the difference in the state of charge (SOC) between battery modules. In the case of a large difference in SOC, some battery modules may reach the fully charged or discharged state in advance, while other battery modules are still performing charge and discharge operations. In this case, in order to avoid damage to individual battery modules due to overcharging or over-discharging, the test system usually needs to terminate the entire PCS system test process in advance, resulting in the test being unable to fully simulate the actual working conditions and reducing the reliability and accuracy of the test.

[0004] Therefore, in view of the above technical problems, it is necessary to provide a new solution. Summary of the Invention

[0005] The purpose of the present invention is to provide a back-to-back test method and system for a string-type PCS system, which can allocate charge and discharge power according to the remaining power of battery modules, improving the accuracy and efficiency of testing.

[0006] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a back-to-back test method for a string-type PCS system, which includes:

[0008] Construct a string-type PCS component, where the string-type PCS component includes a first PCS component and a second PCS component connected in series to form a charge-discharge loop. Both the first PCS component and the second PCS component include multiple battery modules, and the battery modules in the first PCS component and the second PCS component can exchange energy; set a target power to enable the first PCS component and the second PCS component to charge and discharge each other; based on the remaining power of each battery module in the first PCS component and the second PCS component, dynamically allocate the charge-discharge power of each battery module so that the total charge-discharge power of each battery module is equal to the target power; wherein, the charging power of each battery module is inversely proportional to its remaining power, and the discharging power of each battery module is directly proportional to its remaining power.

[0009] In one or more embodiments, in the discharging state, the discharging power of each battery module is allocated according to the following formula:

[0010] P n =P max ×SOC n / SOC max ;

[0011] Wherein, P n is the discharging power of battery module n, SOC n is the remaining power of battery module n, P max is the discharging power of the battery module with the highest remaining power in the discharging state; SOC max is the remaining power of the battery module with the highest remaining power in the discharging state.

[0012] In one or more embodiments, in the charging state, the charging power of each battery module is allocated according to the following formula:

[0013] P n '=P max '×SOC min / SOC n ;

[0014] Wherein, P n 'is the charging power of battery module n, SOC n is the remaining power of battery module n, P max 'is the charging power of the battery module with the lowest remaining power in the charging state; SOC min is the remaining power of the battery module with the lowest remaining power in the charging state.

[0015] In one or more embodiments, the total discharging power P e of each battery module is based on the formula P e =P1 +P 2 +P 3 +…+P n Calculated; the total charging power P of each battery module e 'According to the formula P e '=P 1 '+P 2 '+P 3 '+…+P n 'Calculated.

[0016] In one or more embodiments, when the total discharge power P e is greater than the target power P o , the discharge power of the battery module in the discharge state is adjusted to P n ×P o / P e ; and / or when the total charging power P e 'is greater than the target power P o , the charging power of the battery module in the charging state is adjusted to P n '×P o / P e '.

[0017] In one or more embodiments, when the total discharge power P e is less than the target power P o , the differential discharge power P o -P e is evenly distributed to the battery modules with unloaded discharge power in the discharge state; and / or when the total charging power P e 'is less than the target power P o , the differential charging power P o -P e 'is evenly distributed to the battery modules with unloaded charging power in the charging state.

[0018] In one or more embodiments, the method further includes: during the process of mutual charge and discharge between the first PCS component and the second PCS component, detecting whether the battery cabinet accommodating the battery module is abnormal. If so, stopping the charge and discharge of the first PCS component and the second PCS component; and / or detecting whether the BMS and PCS of each battery module are disconnected. If so, prohibiting the battery module with the BMS and PCS disconnected and its opposite-side battery module from participating in the charge and discharge; and / or detecting whether the PCS of each battery module is in the standby state. If so, prohibiting the battery module with the PCS in the standby state and its opposite-side battery module from participating in the charge and discharge; and / or detecting whether the battery cluster of each battery module is abnormal. If so, prohibiting the battery module with the abnormal battery cluster and its opposite-side battery module from participating in the charge and discharge.

[0019] In one or more embodiments, the method further includes: when the power of the battery module in the charging state is higher than the first threshold, adjusting the charging power of the battery module to 20% - 30% of its rated power, and switching to the constant current charging mode; and / or when the power of the battery module in the discharging state is lower than the second threshold, adjusting the discharging power of the battery module to 20% - 30% of its rated power, and switching to the constant current discharging mode.

[0020] In one or more embodiments, the method further includes: when the battery module in the charging state is fully charged, turning off the PCS of the battery module and its opposite-side battery module; and / or when the battery module in the discharging state is fully discharged, turning off the PCS of the battery module and its opposite-side battery module.

[0021] In a second aspect, the present invention provides a PCS back-to-back test system, which includes: a string-type PCS component, a setting module, and a distribution module; the string-type PCS component includes a first PCS component and a second PCS component connected in series to form a charging and discharging loop, both the first PCS component and the second PCS component include a plurality of battery modules, and the battery modules in the first PCS component and the second PCS component can exchange energy; the setting module is used to set a target power so that the first PCS component and the second PCS component perform charging and discharging with each other; the distribution module is used to dynamically distribute the charging and discharging power of each battery module based on the remaining power of each battery module in the first PCS component and the second PCS component, so that the total charging and discharging power of each battery module is equal to the target power; wherein, the charging power of each battery module is inversely proportional to its remaining power, and the discharging power of each battery module is directly proportional to its remaining power.

[0022] Compared with the prior art, the back-to-back test method and system of the string-type PCS system provided by the present invention can realize the recycling of the charging and discharging energy of the energy storage battery by constructing a closed-loop test system, save the energy cost in the charging and discharging process, reduce the purchase cost of high-power loads, and make the entire test scheme more economical and efficient; distribute power according to the remaining power of the battery to ensure that the working state of each battery module matches the target power, thereby avoiding damage to the battery due to overcharging or over-discharging and improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1Schematic diagram of the architecture of the string-type PCS component in an embodiment of the present invention;

[0025] Figure 2 Flowchart of the back-to-back test method for the string-type PCS system in an embodiment of the present invention;

[0026] Figure 3 Block diagram of the structure of the PCS back-to-back test system in an embodiment of the present invention. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] In the research and development and testing process of the energy storage system, the performance evaluation of the power conversion system (PCS) is an important link to ensure the stability of the system and optimize the operation strategy. The existing PCS test methods usually test each battery module with a fixed charge and discharge power. However, this method does not fully consider the difference in the state of charge (SOC) between different battery modules, resulting in multiple problems during the test, including asynchronous charge and discharge times, reduced test accuracy, low energy utilization rate, and the risk of overcharging or over-discharging of the battery module. In addition, the test system lacks the ability of dynamic adjustment, making it difficult for the test results to truly reflect the performance of the PCS system in a complex operating environment.

[0029] Based on this, the present invention proposes a back-to-back test method for a string-type PCS system. The core implementation idea is to construct a closed-loop charge and discharge circuit to enable the recycling of energy within the test system and dynamically allocate the charge and discharge power based on the SOC of the battery module to ensure the synchronization and efficiency of the test process.

[0030] Specifically, the present invention constructs a system architecture composed of two mutually closed-loop PCS components, enabling the mutual exchange and recycling of energy between the two components, thus breaking through the limitation of the unidirectional fixed power application in traditional tests. This closed-loop architecture not only improves the energy utilization efficiency but also provides a system basis for subsequent power regulation.

[0031] Regarding the overall performance requirements during the test, the present invention introduces the concept of target power setting. This target power serves as the overall requirement for the entire system test, guiding each battery module in the system to jointly achieve the predetermined energy transfer task during the charge and discharge process.

[0032] To solve the problem of uneven charge and discharge states caused by differences in the remaining power of each battery module, the present invention adopts a dynamic power distribution strategy based on the remaining power information. During the entire test process, the charge and discharge power of each battery module is adjusted in real time according to its remaining power, so that the energy distribution of each battery module tends to be balanced, enabling all modules to complete the charge and discharge cycle within a similar time, avoiding the phenomena of early charge or late discharge caused by uneven energy in traditional fixed-power tests, and thus improving the synchronization and accuracy of the test.

[0033] Please refer to Figure 1 As shown, it is a schematic diagram of the architecture of a string-type PCS component in an embodiment of the present invention. In this architecture, the string-type PCS component mainly consists of a battery cabinet, and a first PCS component and a second PCS component housed in the battery cabinet. The battery cabinet, as the main structure of the system, provides necessary support and safety protection, enabling all battery modules to perform charge and discharge tests in a controlled environment. The first PCS component and the second PCS component respectively accommodate multiple battery modules. Among them, each battery module consists of a PCS (energy storage converter) and a cluster of battery clusters. The PCS is used to regulate the charge and discharge power of the battery module to ensure the power matching of the battery module and the stability of the energy conversion process.

[0034] The first PCS component and the second PCS component are connected in series to form a charge and discharge loop, enabling energy exchange between the two PCS components. When the battery modules in the first PCS component are in the charging state, the battery modules in the second PCS component are in the discharging state, and vice versa. This mutually compensatory energy exchange mechanism can reduce the consumption of external energy during the test, ensure that the battery modules inside the system maintain energy balance under different working states, and improve the energy efficiency ratio of the test system.

[0035] The core control part of the entire string-type PCS component is the PCS controller, which is connected to both the first PCS component and the second PCS component, and undertakes the tasks of power distribution and charge and discharge management of the entire system. Based on the SOC (State of Charge, remaining power), charge and discharge requirements of each battery module, and the operating state of the system, the PCS controller adjusts the power output of each PCS in real time to ensure that the system operates according to the preset target power.

[0036] In addition, to ensure the safety of the entire string-type PCS component, an intelligent monitoring mechanism can be further introduced on the basis of the PCS controller to obtain the environmental parameters of the battery cabinet, key parameters such as the temperature, current, and voltage of the battery module in real time, and dynamically adjust the charge and discharge strategy according to these data to prevent overcharge, over-discharge, or power overload situations from occurring.

[0037] Please refer toFigure 2 As shown, it is a flowchart of the back-to-back test method for a string-type PCS system in an embodiment of the present invention. The back-to-back test method for the string-type PCS system specifically includes the following steps:

[0038] S201: Construct a string-type PCS component. The string-type PCS component includes a first PCS component and a second PCS component connected in series to form a charge-discharge loop. Both the first PCS component and the second PCS component include a plurality of battery modules, and the battery modules in the first PCS component and the second PCS component can exchange energy.

[0039] By constructing the string-type PCS component, through electrical series connection, the battery modules in the first PCS component and the battery modules in the second PCS component can achieve energy exchange. For example, when the battery modules in the first PCS component are in the discharge state, the energy released by them can be directly transferred to the battery modules in the second PCS component that are in the charging state, thus forming a closed-loop energy transfer system. That is, one of the first PCS component and the second PCS component is used for charging, and the other is used for discharging; and any battery module in the first PCS component has a paired battery module (opposite-side battery module) in the second PCS component.

[0040] The architecture of the string-type PCS component can refer to Figure 1 the PCS component architecture shown, or it can be other architectures, as long as the energy exchange between the battery modules in the first PCS component and the second PCS component can be achieved.

[0041] Traditional PCS test methods usually use an external load to consume the energy released by the battery, or test the battery through independent charge-discharge equipment. However, this method has significant energy losses and high test costs. In contrast, the present invention uses the first PCS component and the second PCS component connected in series to form a closed-loop charge-discharge loop, enabling the energy in the system to be directly transmitted and recycled between the two PCS components, avoiding the resource waste caused by direct energy consumption in the traditional method.

[0042] S202: Set a target power to make the first PCS component and the second PCS component charge and discharge with each other.

[0043] The user can set the target power through the configuration interface of the system to ensure that the first PCS component and the second PCS component can charge and discharge according to the established energy flow pattern during the test.

[0044] The setting of the target power is usually based on the test requirements and the operating characteristics of the battery modules. For example, in a set of PCS tests, assuming that the maximum power capacity of the entire system is 200 kW and the current test requires operation at 50% load, the target power can be set to 100 kW, enabling the battery modules of the first PCS component to discharge at a total power of 100 kW, while the battery modules of the second PCS component charge at a total power of 100 kW. This equivalent power exchange can ensure balanced energy flow during the test process.

[0045] In an exemplary embodiment, during the charging and discharging process between the first PCS component and the second PCS component, it is detected whether the battery cabinet housing the battery modules has any abnormalities. If so, the charging and discharging of the first PCS component and the second PCS component are stopped. And / or it is detected whether the BMS of each battery module is disconnected from the PCS. If so, the battery module with the BMS disconnected from the PCS and its counterpart battery module are prohibited from participating in the charging and discharging. And / or it is detected whether the PCS of each battery module is in the standby state. If so, the battery module with the PCS in the standby state and its counterpart battery module are prohibited from participating in the charging and discharging. And / or it is detected whether there are any abnormalities in the battery clusters of each battery module. If so, the battery module with the abnormal battery cluster and its counterpart battery module are prohibited from participating in the charging and discharging.

[0046] During the charging and discharging process between the first PCS component and the second PCS component, the system can continuously monitor the operating status of the battery modules in real time to ensure the stability, safety, and efficiency of the entire system. The PCS test system involves high-power battery charging and discharging, and any abnormal situation (such as overheating, connection disconnection, device standby, or battery cluster failure) may cause test data distortion and even pose safety hazards. Therefore, the system can adopt an intelligent detection mechanism to respond promptly when an abnormality occurs and avoid affecting the entire test process.

[0047] For example, temperature sensors and smoke detectors can be used to detect in real time whether there is an abnormal increase in temperature or smoke in the battery cabinet housing the battery modules. If it is detected that the temperature exceeds the preset threshold or there is smoke, it indicates that there may be a fire hazard or a risk of equipment overheating in the battery cabinet. At this time, the system will immediately stop the charging and discharging operations of the first PCS component and the second PCS component to quickly cut off the power transmission and send a fault warning signal to the control center, thereby avoiding the expansion of the accident and protecting the safety of equipment and personnel.

[0048] The system can also detect the connection status between the BMS (Battery Management System) and the PCS in each battery module. The BMS is responsible for monitoring parameters such as the voltage, current, and temperature of the battery, while the PCS is responsible for regulating the charging and discharging power of the battery. If it is found during the detection process that the connection between the BMS and the PCS of a certain battery module is disconnected, then this battery module may not be able to accurately transmit battery status information (key data such as SOC, voltage, current, etc.), resulting in unachievable power regulation. To prevent potential safety hazards caused by information mismatch or control failure, the system will prohibit this battery module and its corresponding opposite-side battery module from participating in the charging and discharging process to ensure the reliability of the overall test data and the safety of system operation.

[0049] For example, in actual tests, if a certain module loses the BMS signal due to poor contact, the system will automatically block this module and its opposite-side module with complementary configuration to avoid overloading or abnormal conditions of other modules caused by power imbalance.

[0050] The system can also monitor the working status of the PCS in each battery module. The PCS plays a role in power regulation during the charging and discharging process. If the PCS of a certain battery module is in the standby state, it means that this module fails to participate in the charging and discharging operation normally, or there is a potential risk of failure, and this PCS cannot perform the charging and discharging tasks according to the set target power. Therefore, the system will prohibit the battery module in the standby state and its paired opposite-side battery module from participating in the charging and discharging operation to ensure that all battery modules participating in the charging and discharging are in an active and stable working state.

[0051] In addition, the system can also monitor the status of the battery clusters in each battery module. As the energy storage unit of the battery module, the status of the battery cluster affects the charging and discharging effect and safety. If it is detected that a certain battery cluster has abnormal conditions, such as abnormal battery cell voltage, abnormal temperature, or other faults, the system will immediately prohibit this battery module and its opposite-side battery module from participating in the charging and discharging operation, thereby preventing the abnormal battery cluster from causing a chain reaction to the entire test system and ensuring the stable operation of the overall system.

[0052] In a string-type PCS system, each battery module will cooperate with an opposite-side battery module for power exchange. When a battery module is prohibited from participating in the charging and discharging, if the opposite-side module continues to work, the opposite-side module will still bear a part of the charging and discharging power, which will exacerbate the power difference between the battery modules. Prohibiting the charging and discharging of the opposite-side battery module at the same time can ensure that the working status of all paired battery modules in the system is consistent and avoid power imbalance of the PCS components on both sides.

[0053] Through the above-mentioned various detection and control measures, the system can monitor the environment, connection status, and each key component in real time during the charging and discharging process, and take emergency measures when abnormalities occur. These protection mechanisms can ensure the safety and stability of the charging and discharging operations, and improve the intelligent level and fault protection ability of the entire test system.

[0054] S203: Dynamically allocate the charging and discharging power of each battery module based on the remaining power of each battery module in the first PCS component and the second PCS component, so that the total charging and discharging power of each battery module is equal to the target power; among them, the charging power of each battery module is inversely proportional to its remaining power, and the discharging power of each battery module is directly proportional to its remaining power.

[0055] In the specific implementation process, the system monitors the remaining power of each battery module (the remaining power of the battery clusters in the battery module) in real time. The remaining power reflects the current available power of the battery clusters in the battery module, and can be provided by the battery management system (BMS). Based on these data, the system dynamically allocates the charging and discharging power of each battery module through calculation to ensure overall power balance, while avoiding overcharging or over-discharging of individual batteries, thereby extending the battery life and ensuring the stable operation of the system.

[0056] Specifically, when the system allocates the charging and discharging power, the charging power is inversely proportional to the remaining power of the battery module. That is, the battery module with a lower remaining power requires more charging power to replenish the power, while the battery module with a higher remaining power has relatively less charging power. This strategy can ensure that each battery module in the battery pack can be reasonably charged, avoiding over-fast or under-charging of some battery modules.

[0057] On the other hand, the discharging power of the battery module is directly proportional to the remaining power. That is, the battery module with a higher remaining power can provide more discharging power, while the battery module with a lower remaining power provides less discharging power. This allocation method can maximize the utilization of the remaining energy of the battery module, while ensuring that the battery module will not be over-discharged during the discharging process, protecting the health status of the battery.

[0058] For example, in a certain test, the first PCS component and the second PCS component each contain five battery modules, and their remaining battery levels are 50%, 60%, 70%, 40%, and 80% respectively. Assuming the target power is 1000W, the system will dynamically allocate power according to the remaining battery level of each battery module. For the allocation of charging power, the battery modules with lower remaining battery levels (such as the battery modules with 40% and 50% battery levels) will receive more charging power; for discharging power, the battery modules with higher remaining battery levels (such as the battery modules with 70% and 80% battery levels) will undertake more discharging tasks. This method can ensure reasonable and efficient energy exchange during the charging and discharging process of each battery module, and avoid damage caused by overcharging or over-discharging of individual battery modules.

[0059] Through the aforementioned dynamic allocation of charging and discharging power, the system can optimize the energy utilization rate during actual operation. The dynamic allocation of charging and discharging power can effectively avoid excessive wear or failure of some battery modules due to unbalanced charging and discharging, and extend the service life of the battery. Moreover, the process of dynamically allocating power can ensure the balance of energy within the battery pack, and avoid the decline of battery performance or failure caused by overcharging or over-discharging of some battery modules.

[0060] In an exemplary embodiment, in the discharging state, the discharging power of each battery module can be allocated according to the following formula:

[0061] P n = P max × SOC n / SOC max ;

[0062] Wherein, P n is the discharging power of battery module n, SOC n is the remaining battery level of battery module n, P max is the discharging power of the battery module with the highest remaining battery level among the battery modules in the discharging state; SOC max is the remaining battery level of the battery module with the highest remaining battery level among the battery modules in the discharging state. P max can be a power value preset by the user, or the smaller power value between the maximum discharging power allowed by the battery cluster BMS in the battery module and the rated power of the PCS.

[0063] The aforementioned method of discharging power allocation considers the relative remaining battery levels of each battery module, and can ensure the load balance between battery modules. In other words, the battery module with a higher discharging power can provide more power output, while the battery module with a lower remaining battery level provides less power output. The purpose of such a design is to avoid over-discharging of some battery modules due to lower remaining battery levels during the discharging process, and ensure the overall performance and stability of the system.

[0064] In an exemplary embodiment, during the charging state, the charging power of each battery module is distributed according to the following formula:

[0065] P n ' = P max ' × SOC min / SOC n ;

[0066] Wherein, P n ' is the charging power of battery module n, SOC n is the remaining power of battery module n, P max ' is the charging power of the battery module with the lowest remaining power among the battery modules in the charging state; SOC min is the remaining power of the battery module with the lowest remaining power among the battery modules in the charging state. P max ' can be a power value preset by the user, or the smaller power value between the maximum charging power allowed by the battery cluster BMS in the battery module and the rated power of the PCS.

[0067] When the system starts charging, the BMS will first identify the battery module with the lowest remaining power, and the charging power P max ' of this battery module will be used as a reference value for all charging battery modules. According to the remaining power of each battery module, its charging power is calculated. The battery module with a lower remaining power will obtain a higher charging power, while the battery module with a higher remaining power will obtain a lower charging power to ensure the synchronization and balance of the charging process of each battery module.

[0068] In an exemplary embodiment, the total discharge power P e of each battery module is calculated according to the formula P e = P 1 + P 2 + P 3 + … + P n ; the total charging power P e ' of each battery module is calculated according to the formula P e ' = P 1 ' + P 2 ' + P 3 ' + … + P n '.

[0069] The total discharge power and the total charging power are respectively obtained by accumulating and calculating the powers of each charge-discharge battery module. By calculating the total charging power and the total discharge power in real time, the system can perform dynamic adjustment according to the preset target power, thereby ensuring the stability of the charge-discharge process.

[0070] In an exemplary embodiment, when the total discharge power Pe Greater than the target power P o When, adjust the discharge power of the battery module in the discharge state to P n ×P o / P e When the total charging power P e ' is greater than the target power P o When, adjust the charging power of the battery module in the charging state to P n '×P o / P e '.

[0071] When the total discharge power P e is greater than the target power P o When, the system needs to adjust the power of each battery module in the discharge state to ensure that the total discharge power of the entire system does not exceed the target power. Specifically, the system adjusts the discharge power P n of each battery module to P n ×P o / P e . This adjustment method is based on the proportional relationship between the current discharge power of each battery module and the total power. In this way, the discharge power of all battery modules will be reduced proportionally to ensure that the total power does not exceed the set target power.

[0072] Similarly, when the total charging power P e ' is greater than the target power P o When, the system also needs to adjust the power of the battery module in the charging state. The specific method is to adjust the charging power P n ' according to P n '×P o / P e '. This adjustment method ensures that during the charging process of the system, the charging power of the battery module will not be too high, resulting in the overall charging power exceeding the preset target.

[0073] In an exemplary embodiment, when the total discharge power P e is less than the target power P o When, divide the differential discharge power P o -P e equally among the battery modules in the discharge state whose discharge power is not fully loaded. When the total charging power P e ' is less than the target power P o When, divide the differential charging power P o -P e ' equally among the battery modules in the charging state whose charging power is not fully loaded.

[0074] When the system detects that the total discharge power P e is less than the target power Po When it is, it indicates that the total discharge power of the current battery module is insufficient, and the system needs to perform power compensation on the battery module in the discharge state to make its total discharge power reach the preset target. Specifically, the system will calculate the difference in discharge power, that is, P o -P e , and then evenly distribute this part of the power to the battery modules that are currently in the discharge state but whose power has not reached full load, so that these battery modules bear additional discharge loads to make up for the shortage of the overall discharge power.

[0075] Similarly, in the charging mode, when the system detects that the total charging power P e ' is less than the target power P o , it indicates that the total charging power of the current battery module cannot meet the preset target power, and the system needs to adjust the power of the battery modules that are in the charging state but whose charging power is not full load to ensure that the overall charging power reaches the set value. The specific method is to calculate the difference P o -P e ' between the target power and the current total charging power, and then evenly distribute this part of the power to the battery modules that are not full load in the charging state to make them bear additional charging tasks.

[0076] Through the foregoing power distribution mechanism, it can be ensured that the power output or input of the system always meets the preset requirements, and avoid unstable power supply to the load or a decrease in charging efficiency due to insufficient power. This balanced distribution mechanism helps to balance the load between battery modules, avoid individual modules from bearing excessive power burdens, thereby extending the service life of the battery and improving the overall reliability of the system.

[0077] In an exemplary embodiment, when the power of the battery module in the charging state is higher than the first threshold, the charging power of the battery module is adjusted to 20% - 30% of its rated power, and it is switched to the constant current charging mode. When the power of the battery module in the discharge state is lower than the second threshold, the discharge power of the battery module is adjusted to 20% - 30% of its rated power, and it is switched to the constant current discharge mode.

[0078] When the power of the battery module in the charging state is close to full charge, continuing to charge at a high power will cause excessive stress on the battery, easily leading to problems such as overheating and overcharging, and even shortening the battery life. Therefore, in this case, the system will adjust the charging power according to the power state of the battery and switch to the constant current charging mode.

[0079] Specifically, when the battery module's power level during charging is higher than the first threshold (which can be set according to actual needs, for example, when the power reaches 90%), that is, when the power is approaching full charge, the system will adjust the charging power of this battery module to 20% - 30% of its rated power. Assuming the rated charging power of the battery module is 100W, when the battery power is approaching full charge, the charging power will be reduced to between 20W and 30W, thereby reducing the risk of overcharging the battery. At the same time, the charging method will change to a constant current charging mode to ensure that the battery can continue to charge stably and safely when approaching full charge, avoiding damage to the battery or reduction of the battery's cycle life due to excessive current. The constant current charging mode can keep a stable charging current when the battery power is approaching 100%, which helps to ensure a smooth and safe battery charging process.

[0080] Similarly, in the discharge state, when the battery module's power level is lower than the second threshold (which can be set according to actual needs, for example, when the power is as low as 10%), that is, when the power is approaching 0, continuing to discharge at a high power may cause over-discharge of the battery, which will also have an adverse impact on the battery's health. To avoid this situation, the system will adjust the discharge power of this battery module to 20% - 30% of its rated power, reducing the risk of over-discharging the battery, and by switching to a constant current discharge mode, ensuring a smoother discharge process of the battery and avoiding excessive consumption of the internal chemical reactions of the battery.

[0081] In specific implementation, the battery management system automatically adjusts the charging or discharging power based on the remaining battery power (SOC) monitored in real time. For example, when the battery power is approaching full charge, the system will gradually reduce the charging current according to the battery management strategy to ensure that both the temperature and current during the charging process are within a safe range. If the charging power drops to the target value, the system will continue to charge steadily through the constant current charging mode until the battery is fully charged.

[0082] In an exemplary embodiment, when the battery module in the charging state is fully charged, the PCS of this battery module and its opposite-side battery module are turned off. When the battery module in the discharge state is fully discharged, the PCS of this battery module and its opposite-side battery module are turned off.

[0083] When the battery module's power reaches 100% (i.e., full charge state), to avoid overcharging, the system will disconnect the power transmission between this battery module and the battery management system. After turning off the PCS, the battery module will no longer receive the charging current from the external power supply, thereby ensuring that the battery will not exceed its designed voltage and current range due to continued charging, avoiding battery overheating, damage, or accelerated aging.

[0084] Similarly, when the battery module in the discharge state is emptied, that is, when the remaining power of the battery module is close to 0, the system will turn off the PCS of this battery module and its opposite-side battery module. During the battery discharge process, if the battery power is completely consumed (i.e., emptied), the discharge current will cause the voltage of the battery module to be too low, which may cause serious damage to the battery and even cause reverse current to flow into the battery, causing irreversible damage to the battery.

[0085] Please refer to Figure 3 As shown, based on the same inventive concept as the back-to-back test method of the foregoing string-type PCS system, the present invention provides a PCS back-to-back test system 300, which includes: a string-type PCS component 301, a setting module 302, and a distribution module 303.

[0086] The string-type PCS component 301 includes a first PCS component and a second PCS component connected in series to form a charge-discharge loop. Both the first PCS component and the second PCS component include a plurality of battery modules, and the battery modules in the first PCS component and the second PCS component can exchange energy. The setting module 302 is used to set a target power so that the first PCS component and the second PCS component charge and discharge each other. The distribution module 303 is used to dynamically distribute the charge-discharge power of each battery module based on the remaining power of each battery module in the first PCS component and the second PCS component, so that the total charge-discharge power of each battery module is equal to the target power; wherein, the charging power of each battery module is inversely proportional to its remaining power, and the discharge power of each battery module is directly proportional to its remaining power.

[0087] In summary, the back-to-back test method and system of the string-type PCS system provided by the present invention can realize the recycling of the charge-discharge energy of the energy storage battery by constructing a closed-loop test system, save the energy cost during the charge-discharge process, reduce the purchase cost of high-power loads, and make the entire test plan more economical and efficient; the SOC of each battery module can be quickly converged through dynamic power distribution, shortening the test cycle; the power is distributed according to the remaining power of the battery to ensure that the working state of each battery module matches the target power, thereby avoiding damage to the battery due to overcharging or over-discharging and improving the test accuracy.

[0088] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. 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. Moreover, the present invention can take the form of a computer program product implemented 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.

[0089] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0090] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for testing a string PCS system, characterized in that: include: Constructing a string-type PCS assembly, wherein the string-type PCS assembly includes a first PCS assembly and a second PCS assembly connected in series to form a charge-discharge loop, wherein the first PCS assembly and the second PCS assembly each include a plurality of battery modules, and the battery modules in the first PCS assembly and the second PCS assembly can exchange energy; Setting a target power so that the first PCS component and the second PCS component can be charged and discharged mutually; Based on the remaining power of each battery module in the first PCS component and the second PCS component, the charging and discharging power of each battery module is dynamically allocated so that the total charging and discharging power of each battery module is equal to the target power; wherein the charging power of each battery module is inversely proportional to its remaining power, and the discharging power of each battery module is directly proportional to its remaining power.

2. The method for testing the string PCS system according to claim 1, characterized in that: In the discharge state, the discharge power of each battery module is distributed according to the following formula: P n =P max ×SOC n / SOC max ; Among them, P n is the discharge power of battery module n, SOC n is the remaining power of battery module n, P max SOC is the discharge power of the battery module with the highest remaining power among the battery modules in the discharge state. max It is the remaining capacity of the battery module with the highest remaining capacity among the battery modules in the discharge state.

3. The method for testing the string PCS system according to claim 2, characterized in that: In the charging state, the charging power of each battery module is distributed according to the following formula: P n '=P max '×SOC min / SOC n ; Among them, P n ' is the charging power of battery module n, SOC n is the remaining power of battery module n, P max ' is the charging power of the battery module with the lowest remaining power among the battery modules in the charging state; SOC min It is the remaining power of the battery module with the lowest remaining power among the battery modules in the charging state.

4. The method for testing the string PCS system according to claim 3, characterized in that: The total discharge power P of each battery module e According to the formula P e =P1+P2+P3+…+P n Calculated; The total charging power P of each battery module e 'According to formula P e '=P1'+P2'+P3'+…+P n 'Calculated.

5. The method for testing the string PCS system according to claim 4, characterized in that: When the total discharge power P e Greater than the target power P o When the discharge power of the battery module in the discharge state is adjusted to P n ×P o / P e ; and / or When the total charging power P e 'Greater than the target power P o When the charging power of the battery module in the charging state is adjusted to P n '×P o / P e '.

6. The method for testing the string PCS system according to claim 4, characterized in that: When the total discharge power P e Less than the target power P o When the difference discharge power P o -P e Evenly distribute to battery modules whose discharge power is not fully loaded in the discharge state; and / or When the total charging power P e ' is less than the target power P o When the difference charging power P o -P e 'Evenly distribute to battery modules that are not fully loaded with charging power during charging.

7. The method for testing the string PCS system according to claim 1, characterized in that: The method further comprises: During the mutual charging and discharging process between the first PCS component and the second PCS component, detecting whether the battery cabinet containing the battery module is abnormal, and if so, stopping the charging and discharging of the first PCS component and the second PCS component; and / or Detect whether the BMS and PCS of each battery module are disconnected. If so, prohibit the battery module whose BMS and PCS are disconnected and its opposite battery module from participating in charging and discharging; and / or Detect whether the PCS of each battery module is in a standby state. If so, prohibit the battery module whose PCS is in the standby state and its opposite battery module from participating in charging and discharging; and / or Check whether the battery cluster of each battery module is abnormal. If so, the battery module with the abnormal battery cluster and its opposite battery module are prohibited from participating in charging and discharging.

8. The method for testing the string PCS system according to claim 1, characterized in that: The method further comprises: When the power level of the battery module in the charging state is higher than the first threshold, adjusting the charging power of the battery module to 20% to 30% of its rated power, and switching to a constant current charging mode; and / or When the electric quantity of the battery module in the discharge state is lower than the second threshold value, the discharge power of the battery module is adjusted to 20% to 30% of its rated power, and the battery module is switched to the constant current discharge mode.

9. The method for testing the string PCS system according to claim 1, characterized in that: The method further comprises: When a battery module in a charging state is fully charged, shutting down the PCS of the battery module and the battery module on the opposite side; and / or When the battery module in the discharge state is emptied, the PCS of the battery module and the battery module on the opposite side are turned off.

10. A PCS pair test system, characterized in that: include: A string-type PCS assembly, comprising a first PCS assembly and a second PCS assembly connected in series to form a charge-discharge loop, wherein the first PCS assembly and the second PCS assembly each comprise a plurality of battery modules, and the battery modules in the first PCS assembly and the second PCS assembly are capable of exchanging energy; A setting module, used for setting a target power so that the first PCS component and the second PCS component can charge and discharge each other; An allocation module is used to dynamically allocate the charging and discharging power of each battery module based on the remaining power of each battery module in the first PCS component and the second PCS component, so that the total charging and discharging power of each battery module is equal to the target power; wherein the charging power of each battery module is inversely proportional to its remaining power, and the discharging power of each battery module is directly proportional to its remaining power.

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