Energy storage system

Abstract

The utility model provides an energy storage system which is provided with a battery module used for storing or transmitting electric quantity and a power conversion module used for realizing bidirectional conversion between direct current and alternating current, and the power conversion module and the battery module are connected in parallel. The power conversion module comprises an H-bridge conversion unit and a capacitor array, the H-bridge conversion unit is used for converting alternating current into direct current or converting direct current voltage into PWM waveform voltage, the capacitor array is used for filtering the direct current converted and generated by the H-bridge conversion unit, and the H-bridge conversion unit and the capacitor array are connected in parallel; the H-bridge conversion unit comprises an upper half-bridge conversion unit and a lower half-bridge conversion unit, each of the upper half-bridge conversion unit and the lower half-bridge conversion unit comprises a plurality of insulated gate bipolar transistor elements, and the insulated gate bipolar transistor elements are used for receiving PWM signals to control the on and off of the H-bridge conversion unit, so that the discrete adaptability of battery energy storage is improved; and the charging and discharging efficiency and the stability of the energy storage system are improved.

Description

Technical Field

[0001] The utility model relates to the field of battery energy storage, in particular to an energy storage system. Background Art

[0002] With the widespread application of renewable energy, the stability and reliability of the power grid are facing huge challenges. As an effective solution, energy storage technology has received more and more attention. Among them, battery energy storage is the key to promote renewable energy from alternative energy to main energy. Energy storage technology has received great attention from energy, transportation, electricity, telecommunications and other industries in various countries.

[0003] In the prior art, battery energy storage systems generally adopt a low-voltage battery pack solution. The battery energy storage system is mainly composed of multiple battery clusters connected in parallel. There is a large circulation current inside the battery clusters, which leads to reduced cyclic energy storage efficiency and instability of the entire battery system. Utility Model Content

[0004] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art, and to provide an energy storage system that can improve the discrete adaptability of battery energy storage, thereby improving the charging and discharging efficiency and stability of the energy storage system.

[0005] To achieve the above objectives, a first aspect of an embodiment of the present application provides an energy storage system, comprising:

[0006] A battery module is used to store or transmit electricity. The battery module includes a battery module;

[0007] A power conversion module, which is used to realize bidirectional conversion between direct current and alternating current, and is connected in parallel with the battery module;

[0008] Among them, the battery module includes multiple battery elements, and the multiple battery elements are connected in series. The power conversion module includes an H-bridge conversion unit and a capacitor array, and the H-bridge conversion unit and the capacitor array are connected in parallel. The H-bridge conversion unit is used to convert alternating current into direct current or convert direct current voltage into PWM waveform voltage. The capacitor array is used to filter the direct current generated by the H-bridge conversion unit. The H-bridge conversion unit includes an upper half-bridge conversion unit and a lower half-bridge conversion unit. The upper half-bridge conversion unit and the lower half-bridge conversion unit both include multiple insulated gate bipolar transistor elements. The capacitor array includes multiple capacitor elements, and the multiple capacitor elements are connected in parallel.

[0009] Further, in some embodiments, the upper half-bridge conversion unit and the lower half-bridge conversion unit are connected in parallel, the multiple insulated gate bipolar transistor elements in the upper half-bridge conversion unit are connected in series, and the multiple insulated gate bipolar transistor elements in the lower half-bridge conversion unit are connected in series.

[0010] Furthermore, in some embodiments, the positive electrode of the capacitor array is connected to the positive electrode of the H-bridge conversion unit, and the negative electrode of the capacitor array is connected to the negative electrode of the H-bridge conversion unit.

[0011] Furthermore, in some embodiments, the positive electrode of the battery module is connected to the positive electrode of the capacitor array, and the negative electrode of the battery module is connected to the negative electrode of the capacitor array.

[0012] Furthermore, in some embodiments, the battery element is a lithium iron phosphate battery element, and the rated capacity of the battery element is 280 Ah.

[0013] Furthermore, in some embodiments, the battery module also includes a battery access circuit and a battery management module. The battery access circuit is used to access the direct current transmitted by the power conversion module and / or pre-charge the battery module. The battery access circuit is connected in series with the battery module. The battery management module is used to detect the working status of each battery element in the battery module. The battery management module is connected to the battery module, and the battery management module is connected to the battery access circuit.

[0014] Furthermore, in some embodiments, the power conversion module includes a bypass unit, which is used to provide a bypass for the energy storage system when a fault occurs. The bypass unit includes a plurality of thyristor elements, and the plurality of thyristor elements are connected in parallel.

[0015] Further, in some embodiments, the effective rated voltage of the thyristor element is 1900V.

[0016] Furthermore, in some embodiments, the energy storage system further includes a control module, the control module is used to control the battery module and / or control the power conversion module, the control module is connected to the battery module, and the control module is connected to the power conversion module.

[0017] Further, in some embodiments, the control module includes a control unit, a driving unit, a communication unit and a sampling unit, the control unit is used to send a PWM signal to the power conversion module, the driving unit is used to amplify the output power of the PWM signal sent by the control unit, the communication unit is used to communicate data with the battery module, and the sampling unit is used to collect the working parameters of the power conversion module.

[0018] An energy storage system according to an embodiment of the utility model has at least the following beneficial effects: by providing a battery module for storing or transmitting electricity and a power conversion module for realizing bidirectional conversion between direct current and alternating current, the power conversion module and the battery module are connected in parallel, so that the energy storage system is easy to maintain and the use cost of the energy storage system is reduced through modular structural design;

[0019] Furthermore, the battery module includes a battery module group, the battery module includes a plurality of battery elements, the plurality of battery elements are connected in series, the power conversion module includes an H-bridge conversion unit for converting alternating current into direct current or converting a direct current voltage into a PWM waveform voltage and a capacitor array for filtering the direct current generated by the H-bridge conversion unit, the H-bridge conversion unit and the capacitor array are connected in parallel, the H-bridge conversion unit includes an upper half-bridge conversion unit and a lower half-bridge conversion unit, the upper half-bridge conversion unit and the lower half-bridge conversion unit both include a plurality of insulated gate bipolar transistor elements, the capacitor array includes a plurality of capacitor elements, the plurality of capacitor elements are connected in parallel, thereby improving the independence and precision of the output power control capability of the energy storage system, reducing the requirements for the consistency of the battery elements, improving the discrete adaptability of the battery energy storage, and thus improving the charging and discharging efficiency and stability of the energy storage system.

[0020] Other features and advantages of the present invention will be described in the following description and will become apparent in part from the description. The purpose and other advantages of the present invention can be realized and obtained through the structures particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the technical solution of the utility model and constitute a part of the specification. Together with the embodiments of the utility model, they are used to explain the technical solution of the utility model and do not constitute a limitation on the technical solution of the utility model.

[0022] The utility model is further described below in conjunction with the accompanying drawings and embodiments;

[0023] Figure 1 It is a structural diagram of an energy storage system provided in an embodiment of the utility model.

[0024] Figure numerals: power conversion module 100, bypass unit 110, thyristor element 111, H-bridge conversion unit 120, upper half-bridge conversion unit 121, lower half-bridge conversion unit 122, capacitor array 130, battery module 200, battery access circuit 210, battery management module 220, battery module 230, battery element 231, control module 300, drive unit 310, communication unit 320, control unit 330, sampling unit 340, insulated gate bipolar transistor element G1, insulated gate bipolar transistor element G2, insulated gate bipolar transistor element G3, insulated gate bipolar transistor element G4. DETAILED DESCRIPTION

[0025] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0026] In the description of the utility model, if there is a description of first and second, it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0028] With the widespread application of renewable energy, the stability and reliability of the power grid are facing huge challenges. As an effective solution, energy storage technology has received more and more attention. Among them, battery energy storage is the key to promote renewable energy from alternative energy to main energy. Energy storage technology has received great attention from energy, transportation, electricity, telecommunications and other industries in various countries.

[0029] In the prior art, battery energy storage systems generally adopt a low-voltage battery pack solution. The battery energy storage system is mainly composed of multiple battery clusters connected in parallel. There is a large circulation current inside the battery clusters, which leads to reduced cyclic energy storage efficiency and instability of the entire battery system.

[0030] In addition, the power conversion modules of the existing battery energy storage system mainly include two types of conversion units, one is a single-phase full-bridge conversion unit, and the other is a three-phase half-bridge conversion unit. The advantage of the single-phase full-bridge conversion module is its simple structure, but its disadvantage is that the output voltage waveform is poor, and it often requires a large-volume filter element for filtering. At the same time, due to the large voltage variation range of the battery pack, a transformer needs to be added to the output end of the battery energy storage system to achieve matching with the power grid or load, which increases the cost and volume of the battery energy storage system and reduces the efficiency of the battery energy storage system. The advantage of the three-phase half-bridge converter is that the output voltage waveform is better and no transformer is required, but its disadvantage is that the structure is complex and requires coordination between multiple switching devices. At the same time, due to the large voltage variation range of the battery pack, a boost circuit needs to be added to the input end of the battery energy storage system to achieve matching with the power grid or load, which will also increase the cost and volume of the battery energy storage system and reduce the efficiency of the battery energy storage system.

[0031] Based on this, the embodiment of the utility model provides an energy storage system, which is provided with a battery module for storing or transmitting electricity and a power conversion module for realizing bidirectional conversion of direct current and alternating current, and the power conversion module and the battery module are connected in parallel, so that the energy storage system is easy to maintain and the use cost of the energy storage system is reduced through modular structure design;

[0032] Furthermore, the battery module includes a battery module, the battery module includes a plurality of battery elements, the plurality of battery elements are connected in series, the power conversion module includes an H-bridge conversion unit for converting AC power into DC power or converting DC voltage into PWM waveform voltage and a capacitor array for filtering the DC power generated by the H-bridge conversion unit, the H-bridge conversion unit and the capacitor array are connected in parallel, the H-bridge conversion unit includes an upper half-bridge conversion unit and a lower half-bridge conversion unit, the upper half-bridge conversion unit and the lower half-bridge conversion unit both include a plurality of insulated gate bipolar transistor elements, the insulated gate bipolar transistor elements are used to receive PWM signals to control the conduction and shutdown of the H-bridge conversion unit, the capacitor array includes a plurality of capacitor elements, and the plurality of capacitor elements are connected in parallel, thereby improving the independence and precision of the output power control capability of the energy storage system, reducing the requirements for the consistency of the battery elements, improving the discrete adaptability of the battery energy storage, and thus improving the charging and discharging efficiency and stability of the energy storage system. Therefore, the following is a further description of the embodiment of the utility model in conjunction with the accompanying drawings.

[0033] Reference Figure 1 As shown, Figure 1 It is a structural diagram of an energy storage system provided by an embodiment of the utility model, the energy storage system includes a power conversion module 100, the power conversion module 100 is used to realize bidirectional conversion of direct current and alternating current, a battery module 200, the battery module 200 is used to store or transmit electricity, the battery module 200 includes a battery module 230, and the power conversion module 100 and the battery module 200 are connected in parallel;

[0034] Among them, the battery module 230 includes a plurality of battery elements 231, and the plurality of battery elements 231 are connected in series. The power conversion module 100 includes an H-bridge conversion unit 120 and a capacitor array 130, and the H-bridge conversion unit 120 and the capacitor array 130 are connected in parallel. The H-bridge conversion unit 120 is used to convert AC power into DC power or convert DC voltage into PWM waveform voltage. The capacitor array 130 is used to filter the DC power generated by the H-bridge conversion unit 120. The H-bridge conversion unit 120 includes an upper half-bridge conversion unit 121 and a lower half-bridge conversion unit 122. The upper half-bridge conversion unit 121 and the lower half-bridge conversion unit 122 both include a plurality of insulated gate bipolar transistor elements (G1, G2, G3, G4), and the insulated gate bipolar transistor elements are used to receive PWM signals to control the conduction and shutdown of the H-bridge conversion unit 120. The capacitor array 130 includes a plurality of capacitor elements (not shown), and the plurality of capacitor elements are connected in parallel, thereby improving the charging and discharging efficiency and stability of the energy storage system.

[0035] Specifically, the upper half-bridge conversion unit 121 is connected in parallel with the lower half-bridge conversion unit 122, a plurality of insulated gate bipolar transistor elements (G1, G2) in the upper half-bridge conversion unit 121 are connected in series, and a plurality of insulated gate bipolar transistor elements (G3, G4) in the lower half-bridge conversion unit 122 are connected in series, thereby being able to improve the trouble-free operation time of the energy storage system through the redundant design of the conversion unit.

[0036] It should be noted that the positive electrode of the capacitor array 130 is connected to the positive electrode of the H-bridge conversion unit 120, and the negative electrode of the capacitor array 130 is connected to the negative electrode of the H-bridge conversion unit 120, thereby improving the waveform quality of the output voltage of the H-bridge conversion unit 120 and reducing the impact of harmonics and noise on the output voltage.

[0037] It should be noted that the positive electrode of the battery module 230 is connected to the positive electrode of the capacitor array 130 , and the negative electrode of the battery module 230 is connected to the negative electrode of the capacitor array 130 .

[0038] In addition, the battery element 231 may be a lithium iron phosphate battery element, thereby improving the safety and service life of the battery module 230 .

[0039] Furthermore, the rated capacity of the battery element 231 may be 280 Ah, which is not specifically limited in the present application.

[0040] Furthermore, the battery module 200 also includes a battery access circuit 210 and a battery management module 220. The battery access circuit 210 is used to access the direct current transmitted by the power conversion module 100 and / or pre-charge the battery module 200. The battery access circuit 210 is connected in series with the battery module 230, thereby being able to provide circuit protection for the battery module 200.

[0041] At the same time, the battery management module 220 is used to detect the working status of each battery element 231 in the battery module 230 and control the connection status between the battery access circuit 210 and the battery module 230. The battery management module 220 is connected to the battery module 230, and the battery management module 220 is connected to the battery access circuit 210.

[0042] Furthermore, the power conversion module 100 includes a bypass unit 110, which is used to provide a bypass for the energy storage system when a fault occurs. The bypass unit 110 includes a plurality of thyristor elements 111, and the plurality of thyristor elements 111 are connected in parallel, so that the energy storage system has an automatic bypass function, thereby improving the reliability of the operation of the energy storage system.

[0043] It should be noted that the effective rated voltage of the thyristor element 111 may be 1900V, which is not specifically limited in the present application.

[0044] Furthermore, the energy storage system also includes a control module 300, which is used to control the battery module 200 and / or control the power conversion module 100. The control module 300 is connected to the battery module 230, and the control module 300 is connected to the power conversion module 100, thereby independently adjusting the output power of the energy storage system, thereby reducing the battery consistency requirements of the energy storage system.

[0045] Specifically, the control module 300 includes a control unit 330, a drive unit 310, a communication unit 320 and a sampling unit 340, which enable the energy storage system to dynamically adjust the combination and control method of the battery module 200 according to external input and output requirements to achieve optimal operation of the energy storage system.

[0046] Among them, the control unit 330 is used to send control instructions to the battery module 230 and send PWM signals to the power conversion module 100, the driving unit 310 is used to amplify the output power of the PWM signal sent by the control unit 330, the communication unit 320 is used to communicate data with the battery module 200, and the sampling unit 340 is used to collect the working parameters of the power conversion module 100, thereby making the power control of the energy storage system more precise and improving the discrete adaptability of the battery module 200.

[0047] Further, the charging principle of the above energy storage system is explained as follows:

[0048] When the energy storage system needs to input electric energy from the outside, the control module 300 starts the system charging control strategy according to the input requirements, controls the H-bridge conversion unit 120 of the power conversion module 100 and the capacitor array 130 to be cascaded, and the alternating current is rectified by the H-bridge conversion unit 120 and converted into pulsating direct current, which is then input into the capacitor array 130. The capacitor array 130 then filters the pulsating direct current to make it a constant direct current; finally, the constant direct current is charged to the battery module 200 and stored in the battery module 230. During the charging process, the H-bridge conversion unit 120 is turned on or off in a certain switching sequence to achieve rectification of the alternating current. At the same time, the battery management module 220 detects and controls the battery module 230 to ensure the safety and balance of the energy storage system.

[0049] Further, the discharge principle of the above energy storage system is explained as follows:

[0050] When the energy storage system needs to output electric energy to the outside world, the control module 300 starts the system discharge control strategy according to the input requirements, and converts the DC power stored in the battery module 230 into a PWM waveform voltage and outputs it (outputting 3 different voltages, namely +U, O and -U) by driving the insulated gate bipolar transistor element of the H-bridge conversion unit 120 to turn on / off. The energy storage system acts as a voltage energy relay pool for PWM output, and the sine wave voltage formed by the series superposition output of multiple battery modules 200 is transmitted to the power grid / load. During the discharge process, the H-bridge conversion unit 120 is turned on or off according to a certain switching sequence, thereby realizing the inversion of the AC power. At the same time, the battery management module 220 detects and controls the battery module 230 to ensure the safety and balance of the energy storage system.

[0051] It should be noted that during the operation of the energy storage system, the control module 300 also detects and manages the battery elements 231 of each battery module 230 through the battery management module 220 to ensure the safety and balance of the battery module 230. At the same time, according to the working status of the battery module 230 and the status of the battery element 231, the control mode of the battery module 230 is dynamically adjusted to achieve the optimal operation of the energy storage system.

[0052] At the same time, the energy storage system can also implement different control charging and discharging strategies according to the state of the battery module 200 and the needs of the power grid or load, and its control charging and discharging strategies include constant power charging and discharging, constant voltage charging and discharging, constant current charging and discharging, etc. For example, if the energy storage system requires constant power charging, the control module 300 calculates the input power corresponding to the power grid or load according to the voltage and current of the power grid or load sampled by the sampling unit 340, and then dynamically adjusts the switching frequency and duty cycle of the H-bridge conversion unit 120 according to the voltage of the energy storage system, so as to keep the input power corresponding to the power grid or load constant.

[0053] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. An energy storage system, characterized in that ,include: A battery module, the battery module is used to store or transmit electricity, and the battery module includes a battery module; A power conversion module, the power conversion module is used to realize bidirectional conversion between direct current and alternating current, and the power conversion module is connected in parallel with the battery module; Among them, the battery module includes multiple battery elements, and the multiple battery elements are connected in series. The power conversion module includes an H-bridge conversion unit and a capacitor array, and the H-bridge conversion unit and the capacitor array are connected in parallel. The H-bridge conversion unit is used to convert alternating current into direct current or convert a direct current voltage into a PWM waveform voltage. The capacitor array is used to filter the direct current generated by the H-bridge conversion unit. The H-bridge conversion unit includes an upper half-bridge conversion unit and a lower half-bridge conversion unit. The upper half-bridge conversion unit and the lower half-bridge conversion unit both include multiple insulated gate bipolar transistor elements. The capacitor array includes multiple capacitor elements, and the multiple capacitor elements are connected in parallel.

2. The energy storage system according to claim 1, characterized in that: The upper half-bridge conversion unit and the lower half-bridge conversion unit are connected in parallel, the multiple insulated gate bipolar transistor elements in the upper half-bridge conversion unit are connected in series, and the multiple insulated gate bipolar transistor elements in the lower half-bridge conversion unit are connected in series.

3. The energy storage system according to claim 1, characterized in that: The positive electrode of the capacitor array is connected to the positive electrode of the H-bridge conversion unit, and the negative electrode of the capacitor array is connected to the negative electrode of the H-bridge conversion unit.

4. The energy storage system according to claim 1, characterized in that: The positive electrode of the battery module is connected to the positive electrode of the capacitor array, and the negative electrode of the battery module is connected to the negative electrode of the capacitor array.

5. The energy storage system according to claim 1, characterized in that: The battery element is a lithium iron phosphate battery element, and the rated capacity of the battery element is 280Ah.

6. The energy storage system according to claim 1, characterized in that: The battery module also includes a battery access circuit and a battery management module. The battery access circuit is used to access the direct current transmitted by the power conversion module and / or pre-charge the battery module. The battery access circuit is connected in series with the battery module. The battery management module is used to detect the working status of each battery element in the battery module. The battery management module is connected to the battery module, and the battery management module is connected to the battery access circuit.

7. The energy storage system according to claim 1, characterized in that: The power conversion module includes a bypass unit, which is used to provide a bypass for the energy storage system when a fault occurs. The bypass unit includes a plurality of thyristor elements, and the plurality of thyristor elements are connected in parallel.

8. The energy storage system according to claim 7, characterized in that: The effective rated voltage of the thyristor element is 1900V.

9. The energy storage system according to claim 1, characterized in that: The energy storage system further includes a control module, which is used to control the battery module and / or the power conversion module. The control module is connected to the battery module, and the control module is connected to the power conversion module.

10. The energy storage system according to claim 9, characterized in that: The control module includes a control unit, a driving unit, a communication unit and a sampling unit. The control unit is used to send a PWM signal to the power conversion module, the driving unit is used to amplify the output power of the PWM signal sent by the control unit, the communication unit is used to communicate data with the battery module, and the sampling unit is used to collect the working parameters of the power conversion module.

Images