Battery grid-connected control method and device, energy storage system and storage medium

Abstract

The application discloses a battery grid-connected control method and device, an energy storage system and a storage medium, wherein the battery grid-connected control method comprises the following steps: acquiring a first current collection value and a first voltage collection value of a battery module in grid operation and acquiring a second voltage collection value of a battery module to be grid-connected; obtaining an actual voltage value of the battery module in grid operation according to the first current collection value and the first voltage collection value; and controlling the battery module to be grid-connected to be grid-connected according to the actual voltage value of the battery module in grid operation and the second voltage collection value. The method and device and the energy storage system can improve the capacity utilization rate of the battery grid-connected system and improve safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of grid-connected control technology, in particular to a battery grid-connected control method, a battery grid-connected control device, an energy storage system and a computer readable storage medium. BACKGROUND

[0002] The current battery module parallel technology is: collecting the voltage of each battery module to sort the voltage, and when the voltage difference between the grid-connected battery module and the non-grid-connected battery module meets the pre-set voltage difference range, the corresponding battery module is started, and the battery module that does not meet the voltage difference is not allowed to start.

[0003] However, the above battery module grid-connected technology has some disadvantages, for example, during charging and discharging, the collected voltage value of the grid-connected running battery module deviates from its actual voltage value, such as being too high or too low, which is different from the static voltage of the actual capacity at this time. If part of the battery modules are in grid-connected operation, the voltage collection value of the non-grid-connected battery module and the voltage difference of the grid-connected running battery module meet the set allowed voltage difference value, and the grid connection will be performed. Since the voltage difference is not real, at this time, the impact current exceeding the allowed range will be generated, resulting in failure of the battery module grid-connected control, which has safety hazards and reduces the battery utilization rate. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the first object of the present application is to propose a battery grid-connected control method which can improve the capacity utilization rate of the battery grid-connected system and improve safety.

[0005] The second object of the present application is to propose a battery grid-connected control device.

[0006] The third object of the present application is to propose an energy storage system.

[0007] The fourth object of the present application is to propose a computer readable storage medium.

[0008] In order to achieve the above-mentioned objects, the battery grid-connected control method of the first aspect of the present application obtains the first current collection value and the first voltage collection value of the grid-connected running battery module and obtains the second voltage collection value of the battery module to be grid-connected; the actual voltage value of the grid-connected running battery module is obtained according to the first current collection value and the first voltage collection value; the battery module to be grid-connected is controlled to be grid-connected according to the actual voltage value of the grid-connected running battery module and the second voltage collection value.

[0009] According to the battery grid-connected control method, the actual voltage value of the battery module in grid operation is obtained according to the first current collection value and the first voltage collection value, so that the difference between the voltage collection value and the actual voltage value of the battery module in grid operation caused by the current collection value is reduced, the grid-connected voltage difference is dynamically calculated more accurately, the inaccuracy of the grid-connected voltage difference caused by the false high or low voltage is avoided, the battery module is in the safe range during the allowed grid connection process, and the harm caused by the impact current is reduced. Moreover, the battery module can be dynamically put into grid connection under the condition of voltage imbalance of the battery module, the maximum utilization rate of the battery is realized, and the balance of the battery module is improved.

[0010] In some embodiments, the actual voltage value of the battery module in grid operation is obtained according to the first current collection value and the first voltage collection value, including:

[0011] An estimated voltage value is obtained according to the first current collection value and the first voltage collection value;

[0012] A weight value of the estimated voltage value and the first voltage collection value is obtained according to the first current collection value;

[0013] The actual voltage value is obtained according to the weight value, the estimated voltage value and the first voltage collection value.

[0014] In some embodiments, the estimated voltage value is obtained according to the first current collection value and the first voltage collection value, including: a voltage influence coefficient is obtained according to the first current collection value, wherein the voltage influence coefficient represents the influence of different current collection values on the actual voltage value; and the estimated voltage value is obtained according to the first current collection value, the first voltage collection value and the voltage influence coefficient.

[0015] In some embodiments, the estimated voltage value is obtained according to the first current collection value, the first voltage collection value and the voltage influence coefficient, including:

[0016] The estimated voltage value is obtained according to the first current collection value, the first voltage collection value and the voltage influence coefficient by the following formula:

[0017] UT=Umod+(Imod / Ci);

[0018] UT is the estimated voltage value, Umod is the first voltage collection value, Imod is the first current collection value, Ci is the influence factor, the voltage influence coefficient is negative when the battery module in grid operation is in the charging state, and the voltage influence coefficient is positive when the battery module in grid operation is in the discharging state.

[0019] In some embodiments, the weight value of the estimated voltage value and the first voltage acquisition value is obtained according to the first current acquisition value, comprising:

[0020] determining a target current acquisition value interval in which the first current acquisition value is located;

[0021] obtaining a first weight value of the first voltage acquisition value according to the target current acquisition value interval;

[0022] obtaining a second weight value of the estimated voltage value according to the first weight value, which is (1-first weight value);

[0023] wherein the first weight value is smaller when the first current acquisition value is smaller; and the weight value satisfies: 0<weight value<1.

[0024] In some embodiments, the voltage actual value is obtained according to the weight value, the estimated voltage value and the first voltage acquisition value, comprising:

[0025] the voltage actual value is obtained by the following formula:

[0026] Ucalc=Umod*x+UT*(1-x);

[0027] wherein Ucalc is the voltage actual value, Umod is the first voltage acquisition value, x is the weight value of the first voltage acquisition value, and (1-x) is the weight value of the estimated voltage value.

[0028] In some embodiments, the battery module to be connected to the grid is controlled to be connected to the grid according to the voltage actual value of the battery module connected to the grid and the second voltage acquisition value, comprising: obtaining a voltage difference between the voltage actual value and the second voltage acquisition value; and when the voltage difference reaches a preset grid connection voltage threshold, the battery module to be connected to the grid is controlled to be connected to the grid.

[0029] In order to achieve the above purpose, the battery grid connection control device of the second aspect embodiment of the present application comprises: a grid connection controller; a memory in communication connection with the grid connection controller; the memory stores a computer program, and the computer program is executed by the grid connection controller to realize the battery grid connection control method.

[0030] The battery grid connection control device according to the embodiment of the present application realizes the battery grid connection control method of the above embodiment through the grid connection controller, achieves the purpose of dynamically calculating the grid connection voltage difference, can better reduce the impact current caused by the grid connection process, and maximizes the guarantee of the battery module to enter the load running state to improve the battery utilization rate.

[0031] To achieve the above object, the energy storage system of the third aspect of the present application comprises: a plurality of battery modules; a plurality of battery controllers, the plurality of battery controllers are connected with the plurality of battery modules correspondingly, and are used for collecting current collection values and voltage collection values of the connected battery modules, wherein the current collection values comprise first current collection values of grid-connected battery modules, and the voltage collection values comprise first voltage collection values of the grid-connected battery modules and second voltage collection values of battery modules to be connected to the grid; and a battery grid-connected control device, which is connected with the plurality of battery controllers.

[0032] According to the energy storage system of the embodiment of the present application, by means of the battery grid-connected control device, the battery grid-connected control method of the above embodiment is executed, the purpose of dynamically calculating the grid-connected voltage difference is achieved, the impact current caused by the grid-connected process can be reduced better, and the battery utilization rate is improved by ensuring that all battery modules enter the load running state as much as possible.

[0033] To achieve the above object, the computer readable storage medium of the fourth aspect of the present application has a computer program stored thereon, and the computer program is executed to realize the battery grid-connected control method.

[0034] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0035] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0036] Figure 1 is a flowchart of a battery grid-connected control method according to an embodiment of the present application;

[0037] Figure 2 is a schematic diagram of a voltage change curve of a battery module charging start process according to an embodiment of the present application;

[0038] Figure 3 is a schematic diagram of a voltage change curve of a battery module in a grid-connected process according to an embodiment of the present application;

[0039] Figure 4 is a block diagram of a battery grid-connected control device according to an embodiment of the present application;

[0040] Figure 5 is a block diagram of an energy storage system according to an embodiment of the present application;

[0041] Figure 6 is a flowchart of a battery module grid-connected control process according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] Embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0043] The embodiments of the present application are described below in detail with reference to the accompanying drawings. Figures 1-3 A battery grid-connected control method according to an embodiment of the first aspect of the present application is described below.

[0044] The basic idea of the battery grid-connected control method of the embodiments of the present application is to dynamically calculate and update the actual voltage value of the battery module according to the periodically collected current collection value of the battery module and the periodically collected voltage collection value of the battery module, so as to achieve the effect of dynamically calculating the allowed maximum voltage difference for grid connection. The allowed grid connection voltage difference is dynamically calculated so that the grid connection process is always within a safe range, greatly improving the grid connection success rate and reducing the impact of the impact current.

[0045] Figure 1 is a flowchart of the battery grid-connected control method according to an embodiment of the present application, as shown in Figure 1 The battery grid-connected control method of the embodiments of the present application includes steps S1-S3.

[0046] S1, obtaining the first current collection value and the first voltage collection value of the battery module in operation, and obtaining the second voltage collection value of the battery module to be connected to the grid.

[0047] In some embodiments, the battery module includes a plurality of series-parallel connected batteries, and each battery module can be monitored by an independent controller to obtain the current and voltage collection values of each battery module. Each controller can communicate with the grid-connected controller, and the grid-connected controller can perform battery grid-connected control.

[0048] For example, each independent controller sends the monitored voltage collection value of the battery module to the grid-connected controller, including the first current collection value and the first voltage collection value of the battery module in operation and the second voltage collection value of the battery module not connected to the grid. The battery module not connected to the grid does not have a current collection value, i.e., the current collection value of the battery module not connected to the grid is zero.

[0049] S2, adjusting the first voltage collection value according to the first current collection value to obtain the actual voltage value of the battery module in operation.

[0050] Specifically, if the battery module is in the parallel charging operation, the battery voltage will cause the collected voltage value to be too high under the influence of the charging current, which is different from the static voltage of the actual capacity at this time. If the battery module is in the parallel discharging operation, the battery voltage will cause the collected voltage value to be too low under the influence of the discharging current, which is different from the static voltage of the actual capacity at this time. Therefore, in the embodiment of the present application, the voltage of each battery module is dynamically calculated according to the current of the battery module during the charging / discharging parallel operation, so that the voltage value used when calculating the parallel voltage difference is closer to the actual voltage of the battery, the parallel success rate is improved, the impact of the impact current is reduced, and the safety is improved.

[0051] In the embodiment, the influence of different current collection values on the voltage collection value of different types of batteries or different sizes of batteries can be obtained through a large amount of experimental data, and the battery module voltage is dynamically adjusted according to the current collection value to be closer to the actual voltage, thereby improving the parallel success rate.

[0052] S3, controlling the battery module to be connected to the grid according to the actual voltage value of the battery module operating in the grid and the second voltage collection value.

[0053] Specifically, the voltage of the battery to be connected to the grid is compared with the actual voltage value of the battery module operating in the grid, and the battery to be connected to the grid is connected to the grid when the voltage difference meets the threshold value.

[0054] For example, the voltage difference between the actual voltage value of the battery module operating in the grid and the second voltage collection value is obtained, and the corresponding battery module to be connected to the grid is controlled to be connected to the grid when the voltage difference reaches the preset parallel voltage threshold value.

[0055] Therefore, the difference between the voltage collection value and the actual voltage value of the battery module operating in the grid caused by the current collection value can be reduced, the parallel voltage difference is dynamically calculated, the inaccuracy of the parallel voltage difference caused by the false high or low voltage is avoided, the battery module is in a safe range during the allowed parallel operation, the harm caused by the impact current is reduced. And it can dynamically put into parallel operation under the condition of unbalanced battery module voltage, realize the maximization of battery utilization rate, and improve the balance of battery module.

[0056] Further, in the embodiment, when the actual voltage value of the battery module operating in the grid is dynamically calculated, an estimated voltage value is obtained according to the first current collection value and the first voltage collection value; the estimated voltage value is obtained by adjusting the voltage collection value according to the current collection value, but the proportion of the influence of the estimated voltage value and the voltage collection value on the actual voltage value is different in different current collection value range, therefore, the weight value of the estimated voltage value and the first voltage collection value can be further obtained according to the first current collection value; the actual voltage value is obtained according to the weight value, the estimated voltage value and the first voltage collection value.

[0057] Specifically, there is a difference between the voltage collection value and the actual voltage value under the current holding, and the voltage influence coefficient of the current size on the collected voltage can be obtained through a large number of experiments, for example, set as Ci. Ci can be a constant corresponding to different current collection value ranges. The voltage influence coefficient Ci is a critical value constant obtained through a large number of experimental data, which will change according to the characteristics of the lithium iron phosphate battery, the power line resistance, the environmental temperature and humidity and other influencing factors. The meaning of Ci can be the influence on the actual voltage value under the influence of different charging and discharging currents. For example, taking a 1000V battery module as an example, the charging current is 80A, which will make the collected voltage higher than the actual voltage by about 4V, so Ci can be taken as 20A / V, and the approximate value is not accurate, which is obtained by experience. The value of other types of batteries or different types and sizes of modules will change accordingly.

[0058] In some embodiments, the voltage influence coefficient is obtained according to the first current collection value, and the estimated voltage value is obtained according to the first current collection value, the first voltage collection value and the voltage influence coefficient. In an embodiment, the relationship among the three can form a relationship formula or form a calculation model or form a data mapping relationship table, which can be directly called by the grid-connected controller when performing grid-connected control.

[0059] For example, the estimated voltage value is obtained according to the first current collection value, the first voltage collection value and the voltage influence coefficient by the following formula:

[0060] UT=Umod+(Imod / Ci);

[0061] UT is the estimated voltage value, Umod is the first voltage collection value, Imod is the first current collection value, and Ci is the influence factor. When the battery module is in the charging state, the voltage influence coefficient is negative, and when the battery module is in the discharging state, the voltage influence coefficient is positive.

[0062] In an embodiment, taking charging as an example, the voltage collection value Umod is higher than the actual voltage value, and the current charging value is negative. Therefore, the calculated UT is smaller than the voltage collection value Umod. By changing the current size, the voltage value is affected differently, different partitions can be taken, different coefficients are used to adjust the proportion of the estimated voltage value and the collected voltage in different partitions, and the calculated filtered voltage value is closer to the actual voltage value.

[0063] For example, the target current collection value interval in which the first current collection value is located is determined, the first weight value of the first voltage collection value is obtained according to the target current collection interval, and the second weight value of the estimated voltage value is obtained according to the first weight value x, which is (1-first weight value). The smaller the first current collection value is, the smaller the first weight value is.

[0064] The weight value can be obtained according to the test, and the weight value mainly considers the influence of the current on the battery voltage, and therefore considers the proportion of the first voltage collection value Umod and the estimated voltage value UT.

[0065] The smaller the current collection value is, the smaller the voltage influence is, and therefore the actual voltage value is closer to the estimated voltage value UT, so that the estimated voltage value UT has a large proportion in the case of a low current collection value, and the estimated voltage value UT has a small proportion in the case of a high current collection value, and then the voltage is smoothed.

[0066] In the embodiment, the voltage actual value can be divided into different zones according to the influence of the current collection value, and the first voltage collection value and the estimated voltage value in each zone can have different weight values. The current division can make the voltage more smoothly approach the voltage actual value, and therefore the division can be determined based on the current change threshold in the embodiment, and the division is more uniform.

[0067] In other modules, when the grid is connected, the current will change, and therefore the voltage adjustment will be calculated according to the division to realize voltage optimization, and the stable current collection value will be stable in a certain interval and will not change.

[0068] In some embodiments, the voltage actual value is obtained by the following formula:

[0069] Ucalc=Umod*x+UT*(1-x);

[0070] Wherein, Ucalc is the voltage actual value, Umod is the first voltage collection value, x is the weight value of the first voltage collection value, and (1-x) is the weight value of the estimated voltage value.

[0071] The different sizes of the current collection value have different influences on the voltage value, and different divisions are taken to calculate the proportion of the estimated voltage value and the voltage collection value in different divisions, that is, the value of x is different in different divisions.

[0072] Further, in the actual data processing process, the current and voltage can be expanded to make the calculation more accurate, and therefore in some embodiments, the voltage actual value can be obtained by the following formula:

[0073] Ucalc=(Umod*x+UT*(1-x)+a)*S / 1*S;

[0074] Wherein, S is the voltage expansion multiple. In the above formula, (+a) is to calculate the rounding after the voltage and current are expanded by a certain multiple. Generally, the value of a is required to be greater than 0.5 to ensure that the rounding after the voltage and current are expanded by a certain multiple is more convenient. Specifically, a can be 0.5, 0.6, etc.

[0075] It should be noted that the above formula is an example of calculating the actual value of the voltage of the present application, and obtaining a transformed formula such as a magnification factor or a constant increase or decrease based on the formula should also fall within the scope of protection of the present application.

[0076] The following is an example of a 10-fold current-voltage magnification. The current collected by the battery module is Imod, which is negative when charging and positive when discharging. The grid-connected controller performs partition filtering calculation according to different current threshold regions. For example, the current collection value threshold is divided into 5 partitions, and of course more partitions or two, three or four partitions are also possible.

[0077] For example, if the absolute value of Imod is less than the threshold TA, the actual value of the voltage is:

[0078] Ucalc=(Umod*x1+UT*(1-x1)+5) / 10;

[0079] If the absolute value of Imod is greater than the threshold TA and less than the threshold TB, the actual value of the voltage is:

[0080] Ucalc=(Umod*x2+UT*(1-x2)+5) / 10; where x2>x1.

[0081] If the absolute value of Imod is greater than the threshold TB and less than the threshold TC, the actual value of the voltage is:

[0082] Ucalc=(Umod*x3+UT*(1-x3)+5) / 10; where x3>x2.

[0083] If the absolute value of Imod is greater than the threshold TC and less than the threshold TD, the actual value of the voltage is:

[0084] Ucalc=(Umod*x4+UT*(1-x4)+5) / 10, where x4>x3

[0085] If the absolute value of Imod is greater than the threshold TD, the actual value of the voltage is:

[0086] Ucalc=(Umod*x5+UT*(1-x5)+5) / 10, where x5>x4.

[0087] The above specific calculation method is periodically executed, so that the battery module collected voltage value is dynamically adjusted by the module collected current value, and then the calculated module voltage value is classified and sorted to achieve the effect of dynamically matching the allowed grid-connected voltage difference to start the corresponding battery module to be connected to the grid.

[0088] For example, Figure 2As shown, the Umod0 curve P1 is the voltage collection value of the battery module requiring grid-connected charging start process, and the U0 (filtering) voltage curve P2 is the voltage value of Umod0 after calculation by the above algorithm, which can reduce the collection error to some extent, so that the voltage value of the battery module used in the parallel controller is closer to the actual capacity voltage value.

[0089] In some embodiments, for example, as Figure 3 As shown, the Umod0 curve is the voltage collection value of the battery module requiring grid connection, U0 (filtering) is the voltage value after calculation by the above algorithm, Umod1 is the voltage collection value of the battery module running in the grid, and U1 (filtering) is the voltage value of Umod1 after calculation by the above algorithm. By comparison, the voltage change during the entire grid connection process can be intuitively obtained. Assuming that the pre-set allowable grid connection voltage difference is 3V, if the module collection voltage value is used, the voltage of Umod0 during the grid connection process will rapidly rise, causing the voltage of Umod0 to rapidly increase after grid connection, and the voltage difference with other modules exceeds the allowable voltage difference, and the module will stop.

[0090] Another case is that the voltage collection value of other modules seems to allow Umod0 to be grid-connected, but the actual capacity voltage has not reached the allowable grid connection voltage, resulting in excessive impact current of Umod0 during grid connection, causing the battery module to stop. Therefore, the calculated voltage can reduce the influence of current on the collected voltage value to some extent, so that the calculated voltage is closer to the actual voltage value, and the voltage value is calculated by continuously updating the collected voltage value and current value, which ensures that the calculated voltage is always dynamically updated, thereby achieving the effect of dynamically calculating the grid connection voltage difference.

[0091] In summary, the battery grid connection control method of the embodiment of the application dynamically calculates and updates the collected module voltage value according to the current loaded by the battery module, achieves the purpose of dynamically calculating the grid connection voltage difference, and can better reduce the impact current caused by the grid connection process and maximize the utilization of the battery module.

[0092] The above battery grid connection control strategy has the following technical effects:

[0093] Higher safety: dynamically calculating the grid connection voltage difference ensures that the battery module is within the safe range during the allowable grid connection process, reducing the harm caused by the impact current. Higher battery utilization: the battery module can be dynamically put into grid connection under the condition of voltage imbalance, maximizing the utilization of the battery. Longer battery use cycle: increasing the grid connection rate can avoid long-term overcharging or undercharging of a single battery module, minimize the inconsistency of the battery in the battery module, and on the other hand, reduce the problem of battery degradation, and maximize the ability of the battery module to store electrical energy.

[0094] Figure 4 is a block diagram of a battery grid-connected control device according to an embodiment of the present application, as Figure 4 shown, the battery grid-connected control device 100 of the embodiment of the present application includes a grid-connected controller 101 and a memory 102 connected in communication with the grid-connected controller 101. The memory 102 stores a computer program, which, when executed by the grid-connected controller 101, implements the battery grid-connected control method of the above embodiment.

[0095] The battery grid-connected control device 100 according to the embodiment of the present application, by the grid-connected controller 101 executing the battery grid-connected control method of the above embodiment, achieves the purpose of dynamically calculating the grid-connected voltage difference, can better reduce the impact current brought by the grid-connected process, and maximizes the possibility of ensuring that all battery modules enter the load running state to improve the battery utilization.

[0096] Figure 5 is a block diagram of an energy storage system according to an embodiment of the present application, as Figure 5 shown, the energy storage system 1000 includes a plurality of battery modules 200, a plurality of battery controllers 300, and the battery grid-connected control device 100 of the above embodiment.

[0097] The plurality of battery controllers 300 are connected in correspondence with the plurality of battery modules 200, for collecting current collection values and voltage collection values of the connected battery modules 200, wherein the current collection values include first current collection values of the grid-connected battery modules, and the voltage collection values include first voltage collection values of the grid-connected battery modules and second voltage collection values of the battery modules to be grid-connected. The battery grid-connected control device 100 is connected with the plurality of battery controllers 300.

[0098] In some embodiments, the battery grid-connected control device 100 dynamically calculates and updates the voltage values of the battery modules according to the periodically collected current values and voltage values of the battery modules, to achieve the effect of dynamically calculating the maximum allowable grid-connected voltage difference, which has the greatest effect in that the dynamically calculated allowable grid-connected voltage difference makes the grid-connected process be within a safe range, greatly improves the grid-connected success rate and reduces the impact of the impact current.

[0099] The main application scenarios include: dynamically calculating the voltage of each battery module according to the current of the battery module during the charging / discharging grid-connected process. In the calculation process, amplifying the current and voltage by 10 times can reduce the error.

[0100] Specifically, as Figure 6 shown, specifically includes:

[0101] S11, sampling data processing, obtaining battery module voltage collection value Umod, battery module current collection value absolute value Imod, and obtaining estimated voltage value UT.

[0102] S12, determine whether Imod≤ threshold TA, if yes, go to step S13, otherwise go to step S14.

[0103] S13, Ucalc= (Umod*1+UT*9+5) / 10.

[0104] S14, determine whether Imod> threshold TA and Imod≤ threshold TB, if yes, go to step S15, otherwise go to step S16.

[0105] S15, Ucalc= (Umod*3+UT*7+5) / 10.

[0106] S16, determine whether Imod> threshold TB and Imod≤ threshold TC, if yes, go to step S17, otherwise go to step S18.

[0107] S17, Ucalc= (Umod*5+UT*5+5) / 10.

[0108] S18, determine whether Imod> threshold TC and Imod≤ threshold TD, if yes, go to step S19, otherwise go to step S20.

[0109] S19, Ucalc= (Umod*7+UT*3+5) / 10.

[0110] S20, determine whether Imod> threshold TTD, if yes, go to step S21, otherwise go to step S22.

[0111] S21, Ucalc= (Umod*9+UT*1+5) / 10.

[0112] S22, end.

[0113] The following is an example, the grid-connected voltage difference is set to 5V, the voltage collection values of the battery module 1 and the battery module 2 are Umod1 (1000V) and Umod2 (1010V) respectively, and the current collection values are Imod1 (0A) and Imod2 (0A). The voltage collection values of the battery module 3 and the battery module 4 are Umod3 (995V) and Umod4 (995V) respectively, and the current collection values are Imod3 (-80A) and Imod4 (-80A).

[0114] Taking the charging condition as an example, the discharging is the opposite:

[0115] If the above grid-connected control method of the embodiment of the present application is not implemented, if the voltage value collected by the battery module 3 and 4 is allowed to differ from the voltage value of the battery module 1 by 5V, the battery module 1 is controlled to be grid-connected, but due to the influence of the charging current, the voltage value of the battery module 3 and 4 is actually smaller than Umod3 and Umod4, and the voltage difference is more than 5V, so the grid-connected battery module 1 will cause the impact current to be too large, resulting in grid connection failure.

[0116] If the above grid-connected control method of the embodiment of the present application is implemented, according to the influence of the current on the voltage in the actual project battery string, for example, it can be divided into 5 sub-zones, and different weight values are used in each sub-zone. According to the formula Ucalc=(Umod*x+UT*(1-x)+5) / 1, the filtered voltage value, i.e. the actual voltage value Ucalc, is closer to the true voltage value. During the calculation process, the current voltage is amplified by 10 times to reduce the error.

[0117] If the absolute value of the battery module 1 and the battery module 2 is lower than the threshold value 20A, the actual voltage value is:

[0118] Ucalc1=(10000V*1+1000V*9+5) / 10.

[0119] Ucalc2=(10000V*1+1000V*9+5) / 10.

[0120] If the absolute value of Imod is greater than the threshold value 20A and lower than the threshold value 40A, the actual voltage value is:

[0121] Ucalc=(Umod*3+UT*7+5) / 10.

[0122] If the absolute value of Imod is greater than the threshold value 40A and lower than the threshold value 60A, the actual voltage value is:

[0123] Ucalc=(Umod*5+UT*5+5) / 10.

[0124] If the absolute value of Imod is greater than the threshold value 60A and lower than the threshold value 80A, the actual voltage value is:

[0125] Ucalc3=(10000V*7+(10000V-800A / 24)*3+5) / 10.

[0126] Ucalc4=(10000V*7+(10000V-800A / 24)*3+5) / 10.

[0127] If the absolute value of Imod is greater than the threshold value 80A, the actual voltage value is:

[0128] Ucalc=(Umod*9x+UT*1x+5) / 10x.

[0129] The above specific calculation method is executed periodically, so that the battery module voltage acquisition value is dynamically adjusted by the module acquisition current value, making Ucalc closer to the actual voltage value. Then, the calculated module voltage values ​​are classified, sorted and arranged to achieve the effect of dynamically matching the allowable grid voltage difference to start the corresponding module.

[0130] For example Figure 2 As shown, the above algorithm can reduce the acquisition error to a certain extent, making the voltage value of the module used in the parallel controller closer to the voltage value of the actual capacity.

[0131] For example Figure 3 As shown, assuming the preset allowable grid-connected voltage difference is 3V, observe the attached... Figure 3 The curves for Umod0 and Umod1 show that when using module-based voltage acquisition, Umod0's own voltage rises rapidly during grid connection. This causes Umod0's voltage to increase rapidly after grid connection, and once the voltage difference with other modules exceeds the allowable differential voltage, the module stops. Another scenario is that the voltage acquisition values ​​from other modules may seem sufficient for Umod0 to connect to the grid, but the actual capacity voltage has not yet reached the allowable grid connection voltage, leading to an excessive inrush current and causing the battery module to stop. Therefore, using the calculated voltage can reduce the influence of current on the acquired voltage value to some extent, making the calculated voltage closer to the actual voltage value. Furthermore, this voltage value is calculated by continuously updating the acquired voltage and current values, ensuring that the calculated voltage is constantly updated dynamically, thus achieving the effect of dynamically calculating the grid connection voltage difference.

[0132] Based on the battery grid-connected control method of the above embodiments, a fourth aspect of the present invention also proposes a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed, implements the battery grid-connected control method of the above embodiments.

[0133] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0134] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery grid-connected control method, characterized in that, include: Acquire the first current and first voltage acquisition values ​​of the battery module operating in the grid, and acquire the second voltage acquisition value of the battery module to be connected to the grid; The actual voltage value of the battery module in operation on the grid is obtained based on the first current acquisition value and the first voltage acquisition value; The system controls the grid-connected battery module to connect to the grid based on the actual voltage value of the battery module already in operation and the second voltage acquisition value. The method of obtaining the actual voltage value of the battery module operating on the grid based on the first current acquisition value and the first voltage acquisition value includes: The estimated voltage value is obtained based on the first current acquisition value and the first voltage acquisition value; The estimated voltage value and the weight value of the first voltage acquisition value are obtained based on the first current acquisition value. The actual voltage value is obtained based on the weight value, the estimated voltage value, and the first voltage acquisition value.

2. The battery grid-connected control method according to claim 1, characterized in that, The estimated voltage value is obtained based on the first current acquisition value and the first voltage acquisition value, including: The voltage influence coefficient is obtained based on the first current acquisition value, wherein the voltage influence coefficient is expressed as the influence of different current acquisition values ​​on the actual voltage value; The estimated voltage value is obtained based on the first current acquisition value, the first voltage acquisition value, and the voltage influence coefficient.

3. The battery grid-connected control method according to claim 2, characterized in that, The estimated voltage value is obtained based on the first current acquisition value, the first voltage acquisition value, and the voltage influence coefficient, including: The estimated voltage value is obtained using the following formula based on the first current acquisition value, the first voltage acquisition value, and the voltage influence coefficient: UT = Umod + (Imod / Ci); Wherein, UT is the estimated voltage value, Umod is the first voltage acquisition value, Imod is the first current acquisition value, and Ci is the voltage influence coefficient. When the on-grid battery module is in the charging state, the voltage influence coefficient is negative, and when the on-grid battery module is in the discharging state, the voltage influence coefficient is positive.

4. The battery grid-connected control method according to claim 3, characterized in that, Obtaining the estimated voltage value and the weighted value of the first voltage acquisition value based on the first current acquisition value includes: Determine the target current acquisition value range in which the first current acquisition value is located; A first weight value for the first voltage acquisition value is obtained based on the target current acquisition value range; The second weight value of the estimated voltage value is (1 - first weight value) obtained based on the first weight value. Wherein, the smaller the first current acquisition value, the smaller the first weight value; The weight values ​​satisfy the following condition: 0 < weight value < 1.

5. The battery grid-connected control method according to claim 4, characterized in that, The actual voltage value is obtained based on the weight value, the estimated voltage value, and the first voltage acquisition value, including: The actual voltage value is obtained using the following formula: Ucalc =Umod * x + UT * (1-x); Wherein, Ucalc is the actual voltage value, Umod is the first voltage acquisition value, UT is the estimated voltage value, x is the weight value of the first voltage acquisition value, and (1-x) is the weight value of the estimated voltage value.

6. The battery grid-connected control method according to any one of claims 1-5, characterized in that, Controlling the grid-connected battery module to connect to the grid based on the actual voltage value of the battery module already in operation and the second voltage acquisition value includes: Obtain the voltage difference between the actual voltage value and the second voltage acquisition value; If the voltage difference reaches the preset grid connection voltage threshold, the battery module to be connected to the grid will be controlled to connect to the grid.

7. A battery grid-connection control device, characterized in that, include: Grid-connected controller; The memory is communicatively connected to the grid-connected controller; The memory stores a computer program, which, when executed by the grid-connected controller, implements the battery grid-connected control method according to any one of claims 1-6.

8. An energy storage system, characterized in that, include: Multiple battery modules; Multiple battery controllers are connected to multiple battery modules respectively, and are used to collect current and voltage data of the connected battery modules. The current data includes a first current data of the battery module operating on the grid, and the voltage data includes a first voltage data of the battery module operating on the grid and a second voltage data of the battery module to be connected to the grid. The battery grid connection control device according to claim 7, wherein the battery grid connection control device is connected to a plurality of the battery controllers.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the battery grid-connected control method according to any one of claims 1-6.

Images