Energy storage system and control method

Abstract

Disclosed in the present invention are an energy storage system and a control method. The energy storage system comprises: several series battery banks, an inverter, and several direct-current voltage processing units respectively corresponding to the series battery banks, wherein each direct-current voltage processing unit comprises an inductor, a first switching transistor, and a second switching transistor. The energy storage system further comprises first capacitors, wherein one end of each first capacitor is connected to an output end of the second switching transistor, and the other end thereof is connected to an output end of the first switching transistor. The control method comprises: detecting an operating state of several series battery banks in an energy storage system, and according to the operating state, identifying an abnormal series battery bank among the several series battery banks; and when the abnormal series battery bank has been identified, switching off a switching transistor of a direct-current voltage processing unit connected to the abnormal series battery bank, and disengaging the abnormal series battery bank from the energy storage system, thus improving the safety and redundancy of the energy storage system.

Description

Energy storage system and control method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 25, 2023, with application number 202310758058.1 and entitled “A Energy Storage System and Control Method,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of battery design, and in particular to an energy storage system and a control method. Background Art

[0003] In the prior art, the battery in the energy storage inverter is an indispensable and important component of the energy storage system. The storage capacity of the battery directly determines the economic value that the energy storage inverter creates for the user. The larger the capacity of the series battery group, the more electrical energy the energy storage system can store when the photovoltaic energy is sufficient. When the photovoltaic energy is insufficient, the energy stored in the battery can be released and used by the load for a longer time.

[0004] In the prior art, methods for expanding the battery capacity of the energy storage inverter include replacing the battery of the energy storage inverter with a larger capacity battery, or increasing the number of batteries in the energy storage inverter by connecting the batteries in series. Replacing the battery of the energy storage inverter requires knowing the capacity of the energy storage system in advance, or constantly changing the battery type to meet the capacity requirements of the energy storage system, thereby causing a waste of resources. The method of using battery series connection is easily affected by the battery voltage requirements of the energy storage inverter, and thus the number of batteries cannot be increased arbitrarily, which reduces the expansion effect of the battery of the energy storage inverter.

[0005] At the same time, whether the type of energy storage inverter battery is replaced or the number of batteries is increased by series connection, when the battery is depleted due to excessive discharge or the battery fails, the entire energy storage system battery will be unable to provide energy and will not work.

[0006] Summary of the Invention

[0007] In order to solve the above problems, the present invention discloses an energy storage system and a control method, which improve the convenience of expanding the capacity of series-connected battery packs and perform charge and discharge balance control on the energy storage system, thereby extending the service life of the energy storage system.

[0008] To achieve the above objectives, in a first aspect, the present invention discloses an energy storage system, comprising: a plurality of series-connected battery packs, an inverter, and a plurality of DC voltage processing units corresponding to the series-connected battery packs; the DC voltage processing units include an inductor, a first switching tube, and a second switching tube; wherein,

[0009] One end of the inductor is connected to the positive electrode of the corresponding series battery group, the other end of the inductor is connected to the input end of the first switching tube, the output end of the first switching tube is connected to the negative electrode of the corresponding series battery group, and the negative electrode of the series battery group is also connected to the negative input end of the DC side of the inverter; the input end of the second switching tube is connected to the input end of the first switching tube, and the output end of the second switching tube is connected to the positive input end of the DC side of the inverter;

[0010] The energy storage system further includes a first capacitor, one end of which is connected to the output end of the second switching tube, and the other end of which is connected to the output end of the first switching tube.

[0011] The present invention provides an energy storage system, which includes several series-connected battery groups and several DC voltage processing units corresponding to the series-connected battery groups, respectively. The several DC voltage processing units are all connected to the inverter so that the series-connected battery groups are controlled according to the DC voltage processing units, thereby improving the convenience of expanding the energy storage system. At the same time, each DC voltage processing unit includes an inductor, a first switching tube, and a second switching tube. The inductor is connected to the positive electrode of the series-connected battery group and the input end of the first switching tube. A first capacitor is also provided in the energy storage system. At the same time, the DC voltage processing unit cooperates with the first switching tube and the second switching tube to complete the use or disconnection of the series-connected battery group, so that when an abnormal battery is detected in the energy storage system, the abnormal battery can be disconnected by controlling the switching tube, thereby improving the safety and redundancy of the energy storage system.

[0012] In one implementation, there are multiple first capacitors corresponding to the DC voltage processing units respectively, and each first capacitor is connected between the output end of the second switching tube and the output end of the first switching tube of the corresponding DC voltage processing unit.

[0013] In the present invention, each DC voltage processing unit is provided with a capacitor connected between the output end of the second switching tube and the output end of the first switching tube to complete the flow of electric energy from the series-connected battery group to the inverter.

[0014] In one implementation, the energy storage system further includes a second capacitor connected between the positive electrode and the negative electrode of the corresponding series-connected battery group.

[0015] The present invention provides a second capacitor in the DC voltage processing unit, connected between the positive electrode and the negative electrode of the series-connected battery pack to stabilize the voltage.

[0016] In one implementation, the several battery groups connected in series include a first battery group connected in series and a second battery group connected in series, wherein the batteries constituting the first battery group connected in series and the batteries constituting the second battery group connected in series have different models and / or specifications; or, the batteries constituting the first battery group connected in series and the batteries constituting the second battery group connected in series have the same model and / or specification.

[0017] The present invention provides that the series-connected battery group includes batteries of different models and specifications, so as to meet the specification requirements of the energy storage inverter for the batteries and improve the scalability of the energy storage system.

[0018] In one implementation, the energy storage system further includes a plurality of relays, each corresponding to the series battery pack, and configured to control the on / off connection between the corresponding series battery pack and the DC voltage processing unit.

[0019] The present invention controls the on / off connection of the connection path between the series-connected battery group and the DC voltage processing unit by controlling the relay, thereby facilitating timely connection or disconnection of the series-connected battery group from the energy storage system and improving the redundancy of the energy storage system.

[0020] In one implementation, the second switch tube is further used to control the on / off of a connection path between the series battery group and the inverter.

[0021] The present invention provides a second switch tube in the DC voltage processing unit for timely connecting or disconnecting the series battery pack from the inverter and stopping power supply to the energy storage system to meet the power supply demand of the energy storage system.

[0022] In a second aspect, the present invention discloses a control method for an energy storage system, comprising:

[0023] Detecting the working status of a plurality of series-connected battery groups in the energy storage system, and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status;

[0024] When the abnormal series-connected battery group is identified, the switch tube of the DC voltage processing unit connected to the abnormal series-connected battery group is disconnected to separate the abnormal series-connected battery group from the energy storage system.

[0025] The present invention provides a control method for an energy storage system. The method detects the working status of a series-connected battery pack in the energy storage system to directly determine whether the energy storage system is abnormal. When an abnormal series-connected battery pack in the energy storage system is identified, the abnormal series-connected battery pack can be directly disconnected from the energy storage system by disconnecting the switch tube of a DC voltage processing unit connected to the abnormal series-connected battery pack, thereby improving the safety and service life of the energy storage system.

[0026] In one implementation, after the abnormal series-connected battery pack is identified, the method further includes: controlling a relay connected to the abnormal series-connected battery pack to be disconnected.

[0027] The present invention realizes the separation of the abnormal series battery group by controlling the disconnection of the relay, so that the energy storage system can be separated from the abnormal series battery group in time, thereby improving the redundancy and service life of the energy storage system.

[0028] In one implementation, detecting the working status of a plurality of series-connected battery groups in the energy storage system and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status includes:

[0029] Monitoring the port voltage of the inverter in the energy storage system;

[0030] It is also determined whether the port voltage is within a preset voltage range. If the port voltage is not within the preset voltage range, it is determined that the series battery pack corresponding to the port voltage is an abnormal series battery pack.

[0031] The present invention determines whether an abnormality occurs in the energy storage system by monitoring the port of the energy storage inverter battery, thereby improving the abnormality detection efficiency.

[0032] In one implementation, the detecting the working status of the plurality of series-connected battery groups in the energy storage system and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status further includes:

[0033] The battery BMS monitors the working status of each series-connected battery group in the energy storage system in real time, and identifies an abnormal series-connected battery group that has failed among the multiple series-connected battery groups based on the working status.

[0034] The present invention detects each series battery group in the energy storage system in real time through the battery BMS, so as to determine the abnormal series battery group that has failed according to the working status of each series battery group, thereby improving the accuracy of abnormality detection.

[0035] In one implementation, after the abnormal series-connected battery group is disconnected from the energy storage system, the control method further includes:

[0036] Obtaining the battery capacity of each series-connected battery group in the energy storage system after the abnormal series-connected battery group is disconnected, and calculating a weight coefficient of each series-connected battery group according to the battery capacity;

[0037] Each of the plurality of series-connected battery groups is charged or discharged according to the weight coefficient.

[0038] The present invention obtains the battery capacity of each series-connected battery group in the energy storage system, and then obtains the weight coefficient of each series-connected battery group based on the battery capacity and a preset weight coefficient calculation formula, so as to facilitate subsequent charge and discharge control of the series-connected battery groups in the energy storage system based on the weight coefficient, so that the series-connected battery groups with high residual capacity discharge more and the series-connected battery groups with low residual capacity discharge less, or the series-connected battery groups with low residual capacity charge more and the series-connected battery groups with high residual capacity charge less, thereby balancing the charge and discharge of each series-connected battery group, thereby improving the system redundancy of the energy storage system.

[0039] In one implementation, calculating the weight coefficient of each series-connected battery pack according to the battery capacity includes:

[0040] Obtaining a total battery current target value of the energy storage system, and comparing the total battery current target value with a preset current threshold;

[0041] If the total battery current target value is greater than the current threshold, obtaining the remaining battery capacity of each series-connected battery group in the energy storage system after the abnormal series-connected battery group is disconnected, comparing the remaining battery capacity of each series-connected battery group with a preset first capacity threshold, screening a plurality of first series-connected battery groups whose remaining battery capacity is less than the first capacity threshold, calculating the remaining battery capacity of the plurality of first series-connected battery groups using a preset first weight coefficient calculation formula, and obtaining first weight coefficients corresponding to each of the plurality of first series-connected battery groups;

[0042] If the total battery current target value is less than the current threshold, the remaining battery capacity of each series battery group in the energy storage system after the abnormal series battery group is disconnected is obtained, the remaining battery capacity of each series battery group is compared with a preset second capacity threshold, and several second series battery groups whose remaining battery capacity is greater than the second capacity threshold are screened. The remaining battery capacity of the several second series battery groups is calculated using a preset second weight coefficient calculation formula to obtain second weight coefficients corresponding to the several second series battery groups.

[0043] The present invention obtains a total battery current target value of the energy storage system and the remaining battery capacity of each series battery group in the energy storage system, so as to calculate a first weight coefficient and a second weight coefficient according to first and second weight coefficient calculation formulas, so that according to the first weight coefficient, the series battery group with low remaining capacity is charged more and the series battery group with high remaining capacity is charged less during the charging process, and according to the second weight coefficient, the series battery group with low remaining capacity is discharged less and the series battery group with high remaining capacity is discharged more during the discharging process, thereby achieving balanced charging and discharging of the energy storage system, ensuring that each series battery group has sufficient battery capacity, and improving battery redundancy.

[0044] In one implementation, charging or discharging each of the plurality of battery groups connected in series according to the weight coefficient includes:

[0045] Obtaining a current target value for each series-connected battery group in the energy storage system based on the total battery current target value, the first weight coefficient, and the second weight coefficient; and comparing the current target value corresponding to each series-connected battery group with a preset charging current limit and a preset discharging current limit, respectively, to select a third series-connected battery group and multiple fourth series-connected battery groups in the energy storage system;

[0046] If the current target value is greater than the charge current limit or the current target value is less than the discharge current limit, selecting the series battery group corresponding to the current target value as the third series battery group, and calculating the current limit amount of the third series battery group, so that the current target value minus the current limit amount is subtracted to charge and discharge the third series battery group;

[0047] If the current target value is less than or equal to the charging current limit value or the current target value is greater than or equal to the discharging current limit value, the series battery group corresponding to the current target value is selected as the fourth series battery group, and the current limits corresponding to the several third series battery groups are added together to obtain the sum of the current limits corresponding to the several third series battery groups; according to the weight coefficient corresponding to the fourth series battery group, the sum of the current limits is added to the fourth series battery group respectively, and the fourth series battery group is charged and discharged.

[0048] The present invention calculates whether the current target value corresponding to each series battery group exceeds the maximum allowable charge and discharge current limit of the series battery group through the total battery current target value and the weight coefficient. If it exceeds, the portion exceeding the limit is shared by other unrestricted series battery groups to bear, thereby achieving the charging and discharging goals of the energy storage system, ensuring the maximum charging and discharging capacity of the energy storage system, and improving the redundancy of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG1 is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention;

[0050] FIG2 is a schematic structural diagram of another energy storage system provided by an embodiment of the present invention;

[0051] 3 is a schematic flow chart of an energy storage system control method provided by an embodiment of the present invention;

[0052] FIG4 is a flow chart of another energy storage system control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0054] The terms "first," "second," and the like in the specification, claims, and accompanying drawings of this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0055] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0056] Example 1

[0057] An embodiment of the present invention provides an energy storage system. Referring to FIG. 1 , the energy storage system includes a plurality of series-connected battery packs 101 , a plurality of DC voltage processing units 102 , and an inverter 103 .

[0058] In one embodiment, the DC voltage processing unit 102 includes an inductor, a first switching tube, and a second switching tube; wherein, one end of the inductor is connected to the positive electrode of the corresponding series battery group 101, the other end of the inductor is connected to the input end of the first switching tube, the output end of the first switching tube is connected to the negative electrode of the corresponding series battery group 101, and the negative electrode of the series battery group 101 is also connected to the DC side negative input end of the inverter 103; the input end of the second switching tube is connected to the input end of the first switching tube, and the output end of the second switching tube is connected to the DC side positive input end of the inverter 103; the energy storage system also includes a first capacitor, one end of the first capacitor is connected to the output end of the second switching tube, and the other end is connected to the output end of the first switching tube.

[0059] The disconnection of the series battery group in the circuit is controlled by the switch tube S1 and the switch tube S2 provided in the DC voltage processing unit. When the series battery group needs to be disconnected from the energy storage system, the series battery group to be disconnected can be disconnected from the energy storage system by disconnecting the switch tube S1 and the switch tube S2 located in the DC / DC converter.

[0060] In one embodiment, the second switch tube is further used to control the on / off of the connection path between the series battery group 101 and the inverter 103 .

[0061] There are a plurality of first capacitors corresponding to the DC voltage processing units 102 , and each first capacitor is connected between the output end of the second switching tube and the output end of the first switching tube of the corresponding DC voltage processing unit 102 .

[0062] In one embodiment, the energy storage system further includes a second capacitor connected between the positive electrode and the negative electrode of the corresponding series battery group 101.

[0063] In one embodiment, the plurality of series-connected battery groups 101 include a first series-connected battery group and a second series-connected battery group, wherein the batteries constituting the first series-connected battery group and the batteries constituting the second series-connected battery group have different models and / or specifications; or, the batteries constituting the first series-connected battery group and the batteries constituting the second series-connected battery group have the same model and / or specification.

[0064] In one embodiment, the energy storage system further includes a plurality of relays, each corresponding to the series battery pack 101 , and configured to control the on / off state of a connection path between the corresponding series battery pack 101 and the DC voltage processing unit 102 .

[0065] For example, the specific structural composition of the system is shown in FIG2 . The energy storage system includes several series-connected battery packs, several DC voltage processing units respectively connected to the series-connected battery packs, and an inverter. The DC voltage processing units utilize DC / DC converters, and the several DC / DC converters are respectively connected to the inverter. The several series-connected battery packs include BAT1, BAT2, ..., BATn, and the several DC / DC converters include DC / DC converter 1, DC / DC converter 2, ..., DC / DC converter n. Users can configure the number of DC / DC converters based on their battery capacity requirements. The series-connected battery packs connected to the DC / DC converters can be of different models and / or specifications but meet the battery specification requirements of the energy storage inverter. Of course, the series-connected battery packs can also be of the same model and specification. A switch SBAT is provided between each series-connected battery pack and the DC / DC converter. The switch SBAT is a relay component (the contacts of a relay can be understood as switches SBAT). The relay controls the opening and closing of the switch SBAT, thereby opening and closing the connection path between the corresponding series-connected battery pack and the DC / DC converter. The DC / DC converter includes a capacitor C, switches S1 and S2, and an inductor L. The input of switch S1 is connected to switch S2 and, via inductor L, to the positive electrode of the series-connected battery pack. The output of switch S1 is connected to the negative electrode of the series-connected battery pack and the negative battery terminal of the inverter, respectively. The output of switch S2 is connected to the positive battery terminal of the inverter. The capacitor C is connected to the positive and negative electrodes of the series-connected battery packs. Referring to Figure 2, a capacitor CBUS (i.e., a second capacitor) is provided in the circuit connecting the multiple DC / DC converters to the inverter, connected to the input and output of the inverter.

[0066] 3 , based on the above energy storage system, the present invention further discloses a method for controlling an energy storage system, including:

[0067] Step 301: Detecting the working status of a plurality of series-connected battery groups in an energy storage system, and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status.

[0068] In one embodiment, this step mainly includes: monitoring the port voltage of the inverter of the energy storage system and determining whether the port voltage is within a preset voltage range. If the port voltage is not within the preset voltage range, determining that the series battery pack corresponding to the port voltage is an abnormal series battery pack. In another embodiment, the battery BMS monitors the operating status of each series battery pack in the energy storage system in real time and identifies the abnormal series battery pack that has a fault among the multiple series battery packs based on the operating status.

[0069] Step 302: When the abnormal series-connected battery group is identified, the switch tube of the DC voltage processing unit connected to the abnormal series-connected battery group is disconnected to separate the abnormal series-connected battery group from the energy storage system.

[0070] For example, based on an energy storage system provided above, referring to FIG2 , when the abnormal series battery group is identified, the switch tube S1 and the switch tube S2 in the DC / DC converter connected to the abnormal series battery group are controlled to be disconnected, so that the circuit where the abnormal battery is located is disconnected, and the abnormal battery is disconnected from the energy storage system.

[0071] In one embodiment, after the abnormal series-connected battery group is identified, a relay connected to the abnormal series-connected battery group may be controlled to be disconnected, so as to disconnect the abnormal series-connected battery group from the energy storage system.

[0072] In one embodiment, after the abnormal series battery group is separated from the energy storage system based on step 302, preferably, the implementation process of the control method further includes steps 401 to 402. Please refer to Figure 4 for the specific implementation process, and the steps mainly include:

[0073] Step 401: Obtain the battery capacity of each series-connected battery group in the energy storage system after the abnormal series-connected battery group is disconnected, and calculate the weight coefficient of each series-connected battery group according to the battery capacity.

[0074] In one embodiment, this step mainly includes: obtaining a total battery current target value of the energy storage system, and comparing the total battery current target value with a preset current threshold; if the total battery current target value is greater than the current threshold, obtaining the remaining battery capacity of each series battery group in the energy storage system after the abnormal series battery group is disconnected, comparing the remaining battery capacity of each series battery group with a preset first capacity threshold, screening several first series battery groups whose remaining battery capacity is less than the first capacity threshold, calculating the remaining battery capacity of the several first series battery groups using a preset first weight coefficient calculation formula, and obtaining first weight coefficients corresponding to the several first series battery groups respectively; if the total battery current target value is less than the current threshold, obtaining the remaining battery capacity of each series battery group in the energy storage system after the abnormal series battery group is disconnected, comparing the remaining battery capacity of each series battery group with a preset second capacity threshold, screening several second series battery groups whose remaining battery capacity is greater than the second capacity threshold, calculating the remaining battery capacity of the several second series battery groups using a preset second weight coefficient calculation formula, and obtaining second weight coefficients corresponding to the several second series battery groups respectively.

[0075] Exemplarily, after obtaining the total battery current target value of the energy storage system, this embodiment compares the total battery current target value with a preset threshold value, and preferably can use this to determine whether the energy storage system needs to be charged or discharged. In one embodiment, it is optionally defined that when the total battery current target value is a positive value, it indicates that the energy storage system is charging, and when the total battery current target value is a negative value, it indicates that the energy storage system is discharging, that is, when the total battery current target value of the energy storage system is greater than zero, it indicates that the energy storage system needs to be charged. In order to achieve a balanced remaining capacity of each series battery group in the energy storage system, the series battery group with low remaining capacity should be charged more, and the series battery group with high remaining capacity should be charged less. At this time, the remaining battery capacity of each series battery group in the energy storage system is obtained, and the remaining capacity is compared with a preset first capacity threshold to determine whether the series battery group needs to be charged. Then, a first weight coefficient of each series battery group that needs to be charged in the energy storage system is obtained by a preset weight coefficient calculation formula. In one embodiment, a weight calculation formula is provided as follows:

[0076] kn=(100%-soc_n) / [(100-soc_1)+(100-soc_2)+…+(100-soc_n)];

[0077] That is, k1=(100%-soc_1) / [(100-soc_1)+(100-soc_2)+…+(100-soc_n)];

[0078] k2=(100%-soc_2) / [(100-soc_1)+(100-soc_2)+…+(100-soc_n)];

[0079] The coefficients k1, k2, and kn are the charging weight coefficients corresponding to the first series battery group, the second series battery group, and the nth series battery group in the energy storage system, and soc_1, soc_2, and soc_n are the remaining battery capacity of the first series battery group, the remaining battery capacity of the second series battery group, and the remaining battery capacity corresponding to the nth series battery group in the energy storage system.

[0080] By analogy, note that when calculating the weight coefficient kn of the last series battery group, in order to eliminate the influence of floating point precision when calculating each weight coefficient, it is guaranteed that k1+k2+…+kn=1 always holds, and kn=1–(k1+k2+…+kn-1).

[0081] When the total battery current target value of the energy storage system is less than zero, it indicates that the energy storage system needs to be discharged. In order to achieve balanced remaining capacity of each series battery group of the energy storage system, the series battery group with low remaining capacity should be discharged less, and the series battery group with high remaining capacity should be discharged more. At this time, the remaining battery capacity of each series battery group in the energy storage system is obtained, and the remaining capacity is compared with a preset second capacity threshold to determine whether the series battery group can be discharged. Then, a second weight coefficient of each series battery group that can be discharged in the energy storage system is obtained by a preset weight coefficient calculation formula. In one embodiment, a weight calculation formula is provided as follows:

[0082] kn=soc_n / (soc_1+soc_2+…+soc_n),

[0083] That is, k1=soc_1 / (soc_1+soc_2+…+soc_n),

[0084] k2=soc_2 / (soc_1+soc_2+…+soc_n),

[0085] The coefficients k1, k2, and kn are the discharge weight coefficients corresponding to the first series battery group, the second series battery group, and the nth series battery group in the energy storage system, and soc_1, soc_2, and soc_n are the remaining battery capacity of the first series battery group, the remaining battery capacity of the second series battery group, and the remaining battery capacity corresponding to the nth series battery group in the energy storage system.

[0086] By analogy, note that when calculating the weight coefficient kn of the last series battery group, in order to eliminate the influence of floating point precision when calculating each weight coefficient, it is guaranteed that k1+k2+…+kn=1 always holds, and kn=1–(k1+k2+…+kn-1).

[0087] Step 402: charging or discharging each of the plurality of series-connected battery groups according to the weight coefficient.

[0088] In one embodiment, the step mainly includes: obtaining the current target value of each series battery group in the energy storage system according to the total battery current target value, the first weight coefficient and the second weight coefficient; respectively comparing the current target value corresponding to each series battery group with the preset charging current limit and the discharge current limit, and screening a plurality of third series battery groups and a plurality of fourth series battery groups in the energy storage system; if the current target value is greater than the charging current limit or the current target value is less than the discharge current limit, screening the series battery group corresponding to the current target value as the third series battery group, and calculating the current of the third series battery group limited amount, so that the current target value is subtracted from the current limited amount to charge and discharge the third series battery group; if the current target value is less than or equal to the charging current limit or the current target value is greater than or equal to the discharging current limit, the series battery group corresponding to the current target value is screened as the fourth series battery group, and the current limited amounts corresponding to the several third series battery groups are added together to obtain the sum of the current limited amounts corresponding to the several third series battery groups; according to the weight coefficient corresponding to the fourth series battery group, the sum of the current limited amounts is added to the fourth series battery group respectively, and the fourth series battery group is charged and discharged.

[0089] Exemplarily, this embodiment calculates the target current value for charging or discharging each series battery group in the energy storage system based on the total battery current target value of the energy storage system and the first or second weight coefficient corresponding to each series battery group, and compares the target current value required to charge or discharge each series battery group with the charging current limit and the discharging current limit corresponding to the series battery group. In one embodiment, the charging current limit of each series battery group is optionally set to Ichargelimit, and the discharging current limit is Idischglimit, where Idischglimit is defined as a negative value. The charging and discharging current limits are jointly determined by the system specification, the energy storage inverter temperature, the battery BMS, etc. If the current target value is greater than Ichargelimit or less than Idischglimit, it indicates that the current target value If the current target limit flag of the current series battery group is limited, the current target limit flag of the current series battery group is set to 1, and the excess limit amount Iover of the current target current value is calculated. When the current target value is greater than Ichargelimit, it indicates that the charging current is limited, Iover = current target value - Ichargelimit; when the current target value is less than Idischglimit, it indicates that the discharge current is limited, Iover = current target value - Idischglimit; the current target limit of each series battery group in the energy storage system is determined separately, and the excess limit amount Iover is calculated. The Iover of each series battery group with limited current targets is added, and then the excess limit amount Iover is added to the series battery group with unrestricted current targets according to the weight coefficient of the series battery group with unrestricted current targets, so as to maintain the maximum charge and discharge capacity of the entire system. In addition, when the current targets of all series battery groups in the system are limited, it means that the charge and discharge capacity of the entire system is limited, and the current state is maintained.

[0090] In addition to the above energy storage system and control method, an embodiment of the present invention further provides a computer storage medium having a computer program stored thereon. When the program is executed by a processor, the control method of the energy storage system described in the embodiment of the present invention is implemented.

[0091] The embodiment of the present invention discloses an energy storage system and a control method, wherein the energy storage system includes a plurality of battery groups connected in series and a plurality of DC voltage processing units, and the plurality of DC voltage processing units are respectively connected to the corresponding battery groups connected in series, and the plurality of DC voltage processing units are all connected to the inverter, so that the battery groups connected in series are controlled according to the DC voltage processing units, thereby improving the convenience of expanding the energy storage system. At the same time, each DC voltage processing unit includes at least one switch tube, so that when an abnormal battery group in series is detected in the energy storage system, the abnormal battery group in series is disconnected by controlling the switch tube, thereby improving the safety and service life of the energy storage system. At the same time, by detecting the working status of the battery group in series in the energy storage system, it is directly judged whether the energy storage system is abnormal. When the abnormal battery group in series is identified in the energy storage system, the switch tube is disconnected. After the abnormal series battery group is connected, the abnormal series battery group can be directly disconnected from the energy storage system by disconnecting the switch tube of the DC voltage processing unit connected to the abnormal series battery group, thereby improving the safety and service life of the energy storage system. After the abnormal series battery group is disconnected from the energy storage system, the battery capacity of each series battery group in the energy storage system is obtained, and then the weight coefficient of each series battery group is obtained according to the battery capacity and a preset weight coefficient calculation formula, so that the series battery groups in the energy storage system can be subsequently charged and discharged according to the weight coefficient, so that the series battery groups with high remaining capacity are discharged more, and the series battery groups with low remaining capacity are discharged less, or the series battery groups with low remaining capacity are charged more, and the series battery groups with high remaining capacity are charged less, so that the charge and discharge of each series battery group are balanced, thereby improving the system redundancy of the energy storage system.

[0092] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. An energy storage system, characterized in that: include: A plurality of series-connected battery groups, an inverter, and a plurality of DC voltage processing units corresponding to the series-connected battery groups; the DC voltage processing unit comprises an inductor, a first switch tube, and a second switch tube; wherein, One end of the inductor is connected to the positive electrode of the corresponding series battery group, the other end of the inductor is connected to the input end of the first switch tube, the output end of the first switch tube is connected to the negative electrode of the corresponding series battery group, and the negative electrode of the series battery group is also connected to the negative electrode input end of the DC side of the inverter; the input end of the second switch tube is connected to the input end of the first switch tube, and the output end of the second switch tube is connected to the positive electrode input end of the DC side of the inverter; The energy storage system further includes a first capacitor, one end of which is connected to the output end of the second switch tube, and the other end of which is connected to the output end of the first switch tube.

2. The energy storage system according to claim 1, characterized in that: There are a plurality of first capacitors corresponding to the DC voltage processing units respectively, and each of the first capacitors is connected between the output end of the second switch tube of the corresponding DC voltage processing unit and the output end of the first switch tube respectively.

3. The energy storage system according to claim 1, characterized in that: The energy storage system further includes a second capacitor connected between the positive electrode and the negative electrode of the corresponding series-connected battery group.

4. The energy storage system according to claim 1, characterized in that: The plurality of battery groups connected in series include a first battery group connected in series and a second battery group connected in series, wherein the batteries constituting the first battery group connected in series and the batteries constituting the second battery group connected in series have different models and / or specifications; or, the batteries constituting the first battery group connected in series and the batteries constituting the second battery group connected in series have the same model and / or specification.

5. The energy storage system according to claim 1, characterized in that: The energy storage system further includes a plurality of relays, each of which corresponds to the series-connected battery packs, and is used to control the on / off of a connection path between the corresponding series-connected battery packs and the DC voltage processing unit.

6. The energy storage system according to any one of claims 1 to 5, characterized in that: The second switch tube is also used for: Controlling the on / off of the connection path between the series-connected battery group and the inverter.

7. A control method for an energy storage system, characterized in that: include: Detecting the working status of a plurality of series-connected battery groups in the energy storage system, and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status; When the abnormal series-connected battery group is identified, the switch tube of the DC voltage processing unit connected to the abnormal series-connected battery group is disconnected to separate the abnormal series-connected battery group from the energy storage system.

8. A control method for an energy storage system according to claim 7, characterized in that: After identifying the abnormal series-connected battery group, the method further includes: controlling a relay connected to the abnormal series-connected battery group to be disconnected.

9. A control method for an energy storage system according to claim 7, characterized in that: The detecting the working status of a plurality of series-connected battery groups in the energy storage system and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status includes: Monitoring the port voltage of the inverter in the energy storage system; It is determined whether the port voltage is within a preset voltage range. If the port voltage is not within the preset voltage range, it is determined that the series-connected battery group corresponding to the port voltage is an abnormal series-connected battery group.

10. A control method for an energy storage system according to claim 7, characterized in that: The detecting the working status of a plurality of series-connected battery groups in the energy storage system and identifying an abnormal series-connected battery group among the plurality of series-connected battery groups according to the working status includes: The battery BMS monitors the working status of each series-connected battery group in the energy storage system in real time, and identifies an abnormal series-connected battery group that has a fault among the several series-connected battery groups based on the working status.

11. A control method for an energy storage system according to claim 7, characterized in that: After the abnormal series battery group is separated from the energy storage system, the control method further includes: Obtaining the battery capacity of each series-connected battery group in the energy storage system after the abnormal series-connected battery group is disconnected, and calculating the weight coefficient of each series-connected battery group according to the battery capacity; Each of the plurality of series-connected battery groups is charged or discharged according to the weight coefficient.

12. A control method for an energy storage system according to claim 11, characterized in that: The calculating the weight coefficient of each series-connected battery group according to the battery capacity includes: Obtaining a total battery current target value of the energy storage system, and comparing the total battery current target value with a preset current threshold; If the total battery current target value is greater than the current threshold, the remaining battery capacity of each series battery group in the energy storage system after the abnormal series battery group is disconnected is obtained, the remaining battery capacity of each series battery group is compared with a preset first capacity threshold, and a plurality of first series battery groups whose remaining battery capacity is less than the first capacity threshold are screened, and the remaining battery capacity of the plurality of first series battery groups is calculated by a preset first weight coefficient calculation formula to obtain first weight coefficients corresponding to the plurality of first series battery groups respectively; If the total battery current target value is less than the current threshold, the remaining battery capacity of each series battery group in the energy storage system after the abnormal series battery group is disconnected is obtained, the remaining battery capacity of each series battery group is compared with a preset second capacity threshold, and a number of second series battery groups whose remaining battery capacity is greater than the second capacity threshold are screened, and the remaining battery capacity of the number of second series battery groups is calculated by a preset second weight coefficient calculation formula to obtain the second weight coefficients corresponding to the number of second series battery groups.

13. The control method of an energy storage system according to claim 11, characterized in that: The charging or discharging each of the plurality of series-connected battery groups according to the weight coefficient comprises: According to the total battery current target value, the first weight coefficient and the second weight coefficient, a current target value of each series-connected battery group in the energy storage system is obtained; the current target value corresponding to each series-connected battery group is compared with the preset charging current limit value and the discharging current limit value, respectively, and a plurality of third series-connected battery groups and a plurality of fourth series-connected battery groups in the energy storage system are screened; If the current target value is greater than the charging current limit value or the current target value is less than the discharging current limit value, then Selecting the series-connected battery group corresponding to the current target value as the third series-connected battery group, and calculating the current limit amount of the third series-connected battery group, so that the third series-connected battery group is charged and discharged by subtracting the current limit amount from the current target value; If the current target value is less than or equal to the charging current limit value or the current target value is greater than or equal to the discharging current limit value, the series battery group corresponding to the current target value is selected as the fourth series battery group, and the current limiting amounts corresponding to the several third series battery groups are added together to obtain the sum of the current limiting amounts corresponding to the several third series battery groups, and according to the weight coefficient corresponding to the fourth series battery group, the sum of the current limiting amounts is respectively superimposed on the fourth series battery group, and the fourth series battery group is charged and discharged.

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