Direct-hanging energy storage system with high overload capacity and energy storage equipment

Abstract

The invention relates to a direct-hanging energy storage system with high overload capacity and energy storage equipment. The direct-hanging energy storage system comprises a direct-current energy storage circuit and at least two commutation circuits. The direct-current energy storage circuit is used for providing direct-current voltage; the first end of the commutation circuit is connected with the first end of the direct-current energy storage circuit or the second end of the adjacent commutation circuit, and the second end of the commutation circuit is connected with the second end of the direct-current energy storage circuit or the first end of the adjacent commutation circuit; the commutation circuit comprises an energy storage module and a full-bridge module, the energy storage module is connected with the full-bridge module, and the full-bridge module is connected with an external power grid; the energy storage module is used for converting a part of the DC voltage into a half-wave sinusoidal voltage, and the full-bridge module is used for converting the half-wave sinusoidal voltage into an AC voltage. According to the invention, the switching device with high surge current resistance is adopted as the switching device of the full-bridge module, so that the capability of the energy storage system for bearing large current is enhanced, the overload resistance is improved, and the operation safety of the energy storage system is ensured.

Description

Technical Field

[0001] The present disclosure relates to the field of direct current (DC) transmission technology, and in particular to a direct-mounted energy storage system and energy storage equipment with high overload capacity. Background Art

[0002] Energy storage systems in power grids store and release electrical energy, playing a vital role in peak and frequency regulation, renewable energy consumption, and large-scale renewable energy transmission. They are essential components in building new power systems. To ensure safe operation, overload resistance is a key factor. Therefore, developing an energy storage system with high overload resistance has become a pressing technical challenge for those skilled in the art. Summary of the Invention

[0003] The present disclosure provides a direct-mounted energy storage system and energy storage equipment with high overload capacity, so as to improve the overload resistance of the energy storage system and thus ensure the safe operation of the energy storage system.

[0004] The present disclosure provides a direct-mounted energy storage system with high overload capacity, comprising: a DC energy storage circuit and at least two commutation circuits. The DC energy storage circuit is configured to provide a DC voltage; a first end of the commutation circuit is connected to a first end of the DC energy storage circuit or a second end of an adjacent commutation circuit; and a second end of the commutation circuit is connected to a second end of the DC energy storage circuit or a first end of an adjacent commutation circuit. The commutation circuit includes an energy storage module and a full-bridge module. The energy storage module is connected to the full-bridge module, and the output end of the full-bridge module is connected to the external power grid. The energy storage module is used to convert part of the DC voltage into a half-wave sinusoidal voltage, and the full-bridge module is used to convert the half-wave sinusoidal voltage into an AC voltage. Among them, the switching device of the full-bridge module is a switching device with the ability to withstand high surge current.

[0005] Optionally, the DC energy storage circuit includes a plurality of DC energy storage modules; the plurality of DC energy storage modules are connected in series; The DC energy storage module includes a DC energy storage unit and a first half-bridge circuit; The first end of the first half-bridge circuit is connected to the first end of the DC energy storage unit, and the second end of the first half-bridge circuit is connected to the second end of the DC energy storage unit; the control end of the first half-bridge circuit is connected to the external control module; The first half-bridge circuit is used to control the working state of the DC energy storage module according to the control signal of the external control module.

[0006] Optionally, the energy storage module includes a plurality of energy storage units; the plurality of energy storage units are connected in series; The energy storage unit includes an energy storage element and a second half-bridge circuit; The first end of the second half-bridge circuit is connected to the first end of the energy storage element, and the second end of the second half-bridge circuit is connected to the second end of the energy storage element; the control end of the second half-bridge circuit is connected to the external control module; The second half-bridge circuit is used to control the working state of the energy storage unit according to the control signal of the external control module.

[0007] Optionally, when the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls to cut out at least one energy storage unit from the multiple energy storage units; When the voltage provided by the energy storage module is less than the modulation wave voltage, the external control module controls at least one energy storage unit to be put into operation from the multiple energy storage units.

[0008] Optionally, when the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage is at least half of the voltage provided by the energy storage module, the external control module determines the magnitude relationship between the voltage provided by the energy storage module and the modulation wave voltage.

[0009] Optionally, the energy storage unit further includes a battery management chip, which is connected to an external control module and is used to obtain the state of charge of the energy storage element; the external control module is used to sort the multiple energy storage units according to the state of charge of the energy storage element; When the energy storage module is in charging state, The external control module controls the energy storage unit with the highest state of charge from multiple energy storage units. Alternatively, the external control module controls the energy storage unit with the lowest state of charge of the energy storage element from among the multiple energy storage units; When the energy storage module is in the discharge state, The external control module controls the energy storage unit with the lowest state of charge from multiple energy storage units. Alternatively, the external control module controls the energy storage unit with the highest state of charge of the energy storage element from among the multiple energy storage units.

[0010] Optionally, the full-bridge module includes four switching units; wherein the switching devices of the switching units are switching devices with high surge current resistance capability; The four switch units include: a first switch unit, a second switch unit, a third switch unit and a fourth switch unit; The first end of the first switch unit and the first end of the third switch unit are connected to the energy storage module, the second end of the first switch unit is connected to the first end of the second switch unit, the second end of the third switch unit is connected to the first end of the fourth switch unit, and the second end of the second switch unit and the second end of the fourth switch unit are connected to the second end of the energy storage module; the control end of the first switch unit, the control end of the second switch unit, the control end of the third switch unit, and the control end of the fourth switch unit are all connected to the external control module; The first switch unit, the second switch unit, the third switch unit and the fourth switch unit are all used to be turned on or off according to the control signal of the external control module, so that the half-wave sinusoidal signal provided by the energy storage module is converted into an AC signal.

[0011] Optionally, the switch unit includes: a plurality of switch devices and a voltage balancing circuit; the plurality of switch devices are connected in series, and the voltage balancing circuits are provided in a one-to-one correspondence with the switch devices; The voltage balancing circuit includes: a first resistor, a first capacitor, and a first diode; The first end of the first resistor is connected to the first end of the first capacitor, the second end of the first resistor is connected to the second end of the first capacitor, the first end of the first capacitor is also connected to the negative end of the first diode, the positive end of the first diode is connected to the first end of the switching device, and the second end of the first capacitor is also connected to the second end of the switching device.

[0012] Optionally, the switching device includes an IGBT, or, IGCT and a second diode; The positive terminal of the IGCT is connected to the negative terminal of the second diode, and the negative terminal of the IGCT is connected to the positive terminal of the second diode.

[0013] The present disclosure also provides an energy storage device, including any direct-mounted energy storage system with high overload capacity as described above.

[0014] The present disclosure provides a direct-mounted energy storage system and energy storage equipment with high overload capacity. The direct-mounted energy storage system includes: a DC energy storage circuit and at least two commutation circuits. The DC energy storage circuit is used to provide a DC voltage; the first end of the commutation circuit is connected to the first end of the DC energy storage circuit or the second end of the adjacent commutation circuit, and the second end of the commutation circuit is connected to the second end of the DC energy storage circuit or the first end of the adjacent commutation circuit; the commutation circuit includes an energy storage module and a full-bridge module, the energy storage module is connected to the full-bridge module, and the output end of the full-bridge module is connected to the external power grid; the energy storage module is used to convert a part of the DC voltage into a half-wave sinusoidal voltage, and the full-bridge module is used to convert the half-wave sinusoidal voltage into an AC voltage and provide it to the external power grid. Among them, the switching device of the full-bridge module is a switching device with the ability to resist high surge current. The present disclosure arranges the DC energy storage circuit and the energy storage module separately, so that the DC energy storage circuit and the energy storage module can be controlled separately, thereby improving the control flexibility of the energy storage system. In addition, in the present disclosure, the switching devices of the full-bridge module adopt switching devices with high surge current resistance, so that the full-bridge module can withstand larger currents, and the entire energy storage system's ability to withstand large currents is also improved, thereby improving the energy storage system's overload resistance and ensuring the safe operation of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A schematic structural diagram of a direct-mounted energy storage system provided in an embodiment of the present disclosure; Figure 2 A schematic structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure; Figure 3 A schematic structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure; Figure 4 A schematic structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure; Figure 5 A schematic structural diagram of a switch unit provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating the examples of the present application.

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The embodiments will be described in detail below with reference to the accompanying drawings.

[0019] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0020] It should be understood that when describing the structure of a component, when a layer or a region is referred to as being "on" or "over" another layer or region, it may mean that it is directly on the other layer or region, or that other layers or regions are included between it and the other layer or region. Furthermore, if the component is turned over, the layer or region will be "below" or "beneath" the other layer or region.

[0021] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0022] In the embodiments of the present application, the term “electrically connected” may refer to a direct electrical connection between two components, or may refer to an electrical connection between two components via one or more other components.

[0023] In the embodiment of the present application, the first node, the second node and the third node are only defined for the convenience of describing the circuit structure. The first node, the second node and the third node are not actual circuit units.

[0024] It will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from the spirit or scope of this application. Therefore, this application is intended to cover modifications and variations of this application that fall within the scope of the corresponding claims (technical solutions claimed for protection) and their equivalents. It should be noted that the embodiments provided in the examples of this application may be combined with each other unless there is any inconsistency.

[0025] The present disclosure provides a direct-hung energy storage system with high overload capacity. The direct-hung energy storage system includes: a DC energy storage circuit and at least two commutation circuits.

[0026] The DC tank circuit is used to provide a DC voltage.

[0027] Exemplarily, the DC energy storage circuit may include, for example, a supercapacitor, an electrochemical battery, etc. The DC energy storage circuit may be used to store electrical energy, and convert the stored electrical energy into a DC voltage and provide it externally.

[0028] The first end of the commutation circuit is connected to the first end of the DC energy storage circuit or the second end of the adjacent commutation circuit, and the second end of the commutation circuit is connected to the second end of the DC energy storage circuit or the first end of the adjacent commutation circuit.

[0029] The commutation circuit includes an energy storage module and a full-bridge module. The energy storage module is connected to the full-bridge module, and the output of the full-bridge module is connected to the external power grid. The energy storage module is used to convert a portion of the DC voltage into a half-wave sinusoidal voltage, and the full-bridge module is used to convert the half-wave sinusoidal voltage into an AC voltage. The switching devices in the full-bridge module are capable of withstanding high surge currents.

[0030] Exemplarily, the at least two commutation circuits may include two commutation circuits, and the two commutation circuits can achieve single-phase output of voltage.

[0031] The at least two commutation circuits may further include three commutation circuits, and the three commutation circuits can realize three-phase output of voltage. Figure 1 A schematic diagram of the structure of a direct-mounted energy storage system provided in an embodiment of the present disclosure is shown in FIG. Figure 1 As shown, the three commutation circuits include a first commutation circuit 21 , a second commutation circuit 22 and a third commutation circuit 23 .

[0032] The first end of the first converter circuit 21 is connected to the first end of the DC energy storage circuit 10, the second end of the first converter circuit 21 is connected to the first end of the second converter circuit 22, the second end of the second converter circuit 22 is connected to the first end of the third converter circuit 23, and the second end of the third converter circuit 23 is connected to the second end of the DC energy storage circuit 10.

[0033] Each commutation circuit also includes an energy storage module 210 and a full-bridge module 220. The energy storage module 210 is connected to the full-bridge module 220, and the output of the full-bridge module 220 is connected to the external power grid 30. The DC energy storage circuit 10 provides a DC voltage to the first commutation circuit 21, the second commutation circuit 22, and the third commutation circuit 23. This can be considered as the DC energy storage circuit 10 providing a portion of the DC voltage to each of the first commutation circuit 21, the second commutation circuit 22, and the third commutation circuit 23. After receiving the partial DC voltage, the energy storage module 210 in each commutation circuit converts this partial voltage into a half-wave sinusoidal voltage and provides it to the full-bridge module 220. By controlling the on and off of each switching device in the full-bridge module 220, the full-bridge module 220 outputs a complete AC voltage to the external power grid 30.

[0034] During the process of the energy storage system converting the DC voltage provided by the DC energy storage circuit 10 into an AC voltage provided to the external power grid 30, since the DC energy storage circuit 10 and the energy storage module 210 are provided separately, the DC energy storage circuit 10 and the energy storage module 210 can be controlled separately. This allows the magnitude of the DC voltage provided by the DC energy storage circuit 10 to be controlled according to the different power demands of the external power grid 30, such as a strong power grid with a large short-circuit ratio or a weak power grid with a small short-circuit ratio. The amplitude and phase of the half-wave sinusoidal voltage provided by the energy storage module 210 can also be controlled, thereby adjusting the AC voltage output by the full-bridge module 220, thereby improving the control flexibility within the energy storage system.

[0035] In addition, the switching devices used in the full-bridge module 220 have the ability to withstand high surge currents, so that the full-bridge module 220 can withstand larger currents. The high current tolerance capability of the entire energy storage system is enhanced due to the enhanced high current tolerance capability of the full-bridge module 220, so the overload resistance of the energy storage system is improved, ensuring the safe operation of the energy storage system.

[0036] The direct-mounted energy storage system provided by the present disclosure also has the ability to operate in four quadrants, so as to send or absorb active power P and reactive power Q to the external power grid 30. Taking the first commutation circuit 21 as an example, the second commutation circuit 22 and the third commutation circuit 23 have the same principle as the first commutation circuit 21. Assume that the effective value of the phase voltage of the AC voltage is U c , the phase is δ, and the effective value of the phase current of the AC current is I c , the power factor angle is φ, and the bridge arm reactance value is L s , so the output power of the energy storage system in the phase where the first commutation circuit 21 is located is:

[0037]

[0038] The output power can also be estimated using the following formula:

[0039]

[0040] In the three-phase symmetrical operation scenario, the output power of each phase is the same, so the total useful power P of the energy storage system is t Output and total reactive power Q t The output is:

[0041]

[0042] Therefore, by controlling the amplitude and phase of the AC voltage generated by each commutation circuit, the output power of the entire energy storage system can be controlled. In actual operation, there is no need to control the full-bridge module 220 to adjust the AC voltage. Instead, the output current and the voltage at the grid connection point are used as the control targets to adjust the output power of the energy storage system.

[0043] In some embodiments, Figure 2 A structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the DC energy storage circuit 10 includes a plurality of DC energy storage modules 100 ; the plurality of DC energy storage modules 100 are connected in series.

[0044] The DC energy storage module 100 includes a DC energy storage unit 110 and a first half-bridge circuit 120 .

[0045] A first end of the first half-bridge circuit 120 is connected to a first end of the DC energy storage unit 110, and a second end of the first half-bridge circuit 120 is connected to the negative terminal of the DC energy storage unit 110. A control end of the first half-bridge circuit 120 is connected to an external control module (not shown). First half-bridge circuit 120 is configured to control the operating state of the DC energy storage module 100 based on a control signal from the external control module.

[0046] Exemplarily, the first half-bridge circuit 120 includes a first switch Q1 and a second switch Q2. A first end of the first switch Q1 is connected to a first end of the DC energy storage unit 110, a second end of the first switch Q1 is connected to a first end of the second switch Q2, and a second end of the second switch Q2 is connected to a second end of the DC energy storage unit 110. The second end of the first switch Q1 is connected to a first end of the commutation circuit 20, or to a second end of a second switch Q2 of an adjacent first half-bridge circuit 120. The second end of the second switch Q2 is connected to a second end of the commutation circuit 20, or to a second end of a first switch Q1 of an adjacent first half-bridge circuit 120.

[0047] The first switch Q1 and the second switch Q2 are controlled to be turned on and off according to the control signal of the external control module, thereby controlling the input or output of the DC energy storage module 100. When the first switch Q1 is turned on and the second switch Q2 is turned off, the DC energy storage unit 110 is connected to the multiple DC energy storage modules 100 connected in series, thereby realizing the input of the DC energy storage module 100. At this time, the DC energy storage unit 110 can be charged or discharged according to the operating state of the energy storage system. When the first switch Q1 is turned off and the second switch Q2 is turned on, the DC energy storage unit 110 is disconnected from the multiple DC energy storage modules 100 connected in series, thereby realizing the output of the DC energy storage module 100. At this time, the DC energy storage unit 110 cannot be charged or discharged, and the input and output of the DC energy storage module 100 are both 0. When both the first switch Q1 and the second switch Q2 are turned off, the DC energy storage module 100 enters a locked state. At this time, the DC energy storage unit 110 can only be charged uncontrolled via the diode connected in reverse parallel to the first switch Q1 and the second switch Q2. The voltage of the DC energy storage module 100 is related to the external circuit and will not exceed the voltage of the DC energy storage unit 110.

[0048] The DC energy storage module 100 also includes a filter unit 130, which can be a filter device such as a capacitor or inductor. The first end of the filter unit 130 is connected to the first end of the DC energy storage unit 110, and the second end of the filter unit 130 is connected to the second end of the DC energy storage unit 110. The filter unit 130 is used to filter out interference signals during the charging and discharging process of the DC energy storage unit 110.

[0049] Furthermore, the external control module can regulate the total voltage of the DC energy storage circuit 10 by controlling the activation and deactivation of the DC energy storage module 100. The external control module also collects the total voltage of the DC energy storage circuit 10 and compares it with a DC voltage threshold. The external control module also detects the state of charge of each DC energy storage unit 110 and sorts the collected state of charge based on their magnitude.

[0050] When the DC energy storage circuit 10 is in a charging state, when the total voltage of the DC energy storage circuit 10 is greater than the DC voltage threshold, and the difference between the two exceeds half the voltage value of the DC energy storage unit 110, the external control module controls the DC energy storage module 100 with the highest state of charge of the DC energy storage unit 110 to be switched off, thereby reducing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold. When the total voltage of the DC energy storage circuit 10 is less than the DC voltage threshold, and the difference between the two exceeds half the voltage value of the DC energy storage unit 110, the external control module controls the DC energy storage module 100 with the lowest state of charge of the DC energy storage unit 110 to be switched on, thereby increasing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold.

[0051] When the DC energy storage circuit 10 is in a discharging state, when the total voltage of the DC energy storage circuit 10 is greater than the DC voltage threshold, and the difference between the two exceeds half the voltage value of the DC energy storage unit 110, the external control module controls the DC energy storage module 100 with the lowest state of charge of the DC energy storage unit 110 to be switched off, thereby reducing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold. When the total voltage of the DC energy storage circuit 10 is less than the DC voltage threshold, and the difference between the two exceeds half the voltage value of the DC energy storage unit 110, the external control module controls the DC energy storage module 100 with the highest state of charge of the DC energy storage unit 110 to be switched on, thereby increasing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold.

[0052] As a result, the present disclosure enables the DC energy storage module 100 to be activated or deactivated based on a comparison of the total voltage of the DC energy storage circuit 10 with the DC voltage threshold, thereby adjusting the total voltage of the DC energy storage circuit 10. This allows the total voltage of the DC energy storage circuit 10 to change in accordance with the DC voltage threshold, thereby ensuring that the average DC voltage of the DC energy storage circuit 10 is equal to the DC voltage threshold. Furthermore, the external control module selects which DC energy storage module 100 to activate or deactivate based on the state of charge of each DC energy storage unit 110, thereby ensuring a balanced state of charge across the entire DC energy storage circuit.

[0053] In some embodiments, Figure 3 A structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure is shown in FIG. Figure 3 As shown, the energy storage module 210 includes a plurality of energy storage units 211; the plurality of energy storage units 211 are connected in series; The energy storage unit 211 includes an energy storage element 2111 and a second half-bridge circuit 2112 .

[0054] A first end of second half-bridge circuit 2112 is connected to the first end of energy storage element 2111, and a second end of second half-bridge circuit 2112 is connected to the second end of energy storage element 2111. A control end of second half-bridge circuit 2112 is connected to an external control module (not shown). Second half-bridge circuit 2112 is configured to control the operating state of energy storage unit 211 based on a control signal from the external control module.

[0055] Exemplarily, the energy storage element 2111 may be, for example, a switched capacitor. The second half-bridge circuit 2112 includes a third switch Q3 and a fourth switch Q4. The first end of the third switch Q3 is connected to the first end of the energy storage element 2111, the second end of the third switch Q3 is connected to the first end of the fourth switch Q4, and the second end of the fourth switch Q4 is connected to the second end of the energy storage element 2111. The second end of the third switch Q3 is connected to the second end of the fourth switch Q4 of the adjacent second half-bridge circuit 2112. The second end of the fourth switch Q4 is connected to the second end of the third switch Q3 of the adjacent second half-bridge circuit 2112.

[0056] According to the control signal of the external control module, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be turned on and off, thereby controlling the input or output of the energy storage unit 211. When the third switch tube Q3 is turned on and the fourth switch tube Q4 is turned off, the energy storage element 2111 is connected to the multiple energy storage units 211 connected in series, thereby realizing the input of the energy storage unit 211. At this time, the energy storage element 2111 can be charged or discharged according to the working state of the energy storage system. When the third switch tube Q3 is turned off and the fourth switch tube Q4 is turned on, the energy storage element 2111 is disconnected from the multiple energy storage units 211 connected in series, thereby realizing the output of the energy storage unit 211. At this time, the energy storage element 2111 cannot be charged or discharged, and the input and output of the energy storage unit 211 are both 0. When the third switch tube Q3 and the fourth switch tube Q4 are both turned off, the energy storage unit 211 enters a locked state. At this time, the energy storage element 2111 can only be charged uncontrolled through the diode connected in reverse parallel with the third switch tube Q3 and the fourth switch tube Q4. The voltage of the energy storage unit 211 is related to the external circuit and will not exceed the voltage of the energy storage element 2111.

[0057] The pulse width modulation signal is generated by the carrier phase shift modulation technology, and the on and off of each switch tube in the second half bridge circuit 2112 is controlled by the pulse width modulation signal, so as to adjust the voltage provided by the energy storage module. c The triangle wave is used as the carrier, and the phase difference between each triangle wave is . With an amplitude of , a half-wave sine wave with a frequency of 100 Hz is used as the modulation wave, where is the peak value of the output AC phase voltage, is the voltage of the energy storage element 2111. The above-mentioned triangular wave and modulation wave are used to obtain a pulse width modulation signal by adopting the carrier phase shift modulation technology.

[0058] In some embodiments, when the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls to cut out at least one energy storage unit from the plurality of energy storage units; When the voltage provided by the energy storage module is less than the modulation wave voltage, the external control module controls at least one energy storage unit to be put into operation from the multiple energy storage units.

[0059] Exemplarily, the external control module can adjust the voltage provided by the energy storage module by controlling the input and output of the energy storage unit. Using level approximation technology, a modulation wave is stored in the external control module, and the voltage provided by the energy storage module is compared with the voltage of the modulation wave. Then, the number of energy storage units connected in series is adjusted according to the comparison result, thereby ensuring that the voltage provided by the energy storage module can always change according to the voltage of the modulation wave. When the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls the output of at least one energy storage unit from the multiple energy storage units, so that the voltage of the energy storage module is reduced to approach the modulation wave voltage. When the voltage provided by the energy storage module is less than the modulation wave voltage, the external control module controls the input of at least one energy storage unit from the multiple energy storage units, so that the voltage of the energy storage module is increased to approach the modulation wave voltage. Therefore, the present disclosure can change the voltage provided by the energy storage module according to the modulation wave provided by the external control module by controlling the input and output of the energy storage units, thereby generating a half-wave sinusoidal voltage formed by a multi-level combination.

[0060] In some embodiments, when the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage is at least half of the voltage provided by the energy storage module, the external control module determines the magnitude relationship between the voltage provided by the energy storage module and the modulation wave voltage.

[0061] For example, if the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage is less than half of the voltage provided by the energy storage module, switching the energy storage unit on or off based on the magnitude relationship between the voltage provided by the energy storage module and the modulation wave voltage will increase the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage, and it cannot be guaranteed that the voltage provided by the energy storage module can change in accordance with the modulation wave voltage. However, if the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage is at least half of the voltage provided by the energy storage module, when the energy storage unit is switched on or off, the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage is still half of the voltage provided by the energy storage module, or is less than half of the voltage provided by the energy storage module. This allows the voltage provided by the energy storage module to approach the modulation wave voltage during the adjustment process, thereby allowing the voltage provided by the energy storage module to change according to the modulation wave to generate a half-wave sinusoidal voltage formed by a multi-level combination.

[0062] In some embodiments, the energy storage unit further includes a battery management chip, which is connected to an external control module and is used to obtain the state of charge of the energy storage element; the external control module is used to sort the multiple energy storage units according to the state of charge of the energy storage element; When the energy storage module is in charging state, The external control module controls the energy storage unit with the highest state of charge from multiple energy storage units. Alternatively, the external control module controls the energy storage unit with the lowest state of charge of the energy storage element from among the multiple energy storage units; When the energy storage module is in the discharge state, The external control module controls the energy storage unit with the lowest state of charge from multiple energy storage units. Alternatively, the external control module controls the energy storage unit with the highest state of charge of the energy storage element from among the multiple energy storage units.

[0063] Specifically, when the energy storage module is in a charging state, if you want to switch out one energy storage unit from multiple energy storage units, you need to select the energy storage unit with the highest state of charge of the energy storage element. This will ensure that the state of charge of the energy storage elements of the multiple energy storage units is relatively uniform, preventing one energy storage unit from completing charging first due to its higher state of charge. If you want to switch in one energy storage unit from multiple energy storage units, you need to select the energy storage unit with the lowest state of charge of the energy storage element to ensure that the switched-in energy storage unit does not complete charging before the others.

[0064] When the energy storage module is in a discharging state, if you want to cut out an energy storage unit from multiple energy storage units, you need to choose to cut out the energy storage unit with the lowest state of charge of the energy storage element, so as to avoid one of the energy storage units completing discharge first due to the lower state of charge of its energy storage element. If you want to put one energy storage unit into the energy storage module from multiple energy storage units, you need to choose to put in the energy storage unit with the highest state of charge of the energy storage element, so as to avoid the put-in energy storage unit completing discharge first compared with the other energy storage units. In this way, during the charging and discharging process, multiple energy storage units can complete charging and discharging at similar times, thereby ensuring the balance of the charge state of the entire energy storage module.

[0065] In some embodiments, Figure 4 A structural diagram of another direct-mounted energy storage system provided in an embodiment of the present disclosure is shown in FIG. Figure 4 As shown, the full-bridge module includes four switch units; wherein the switch devices of the switch units are switch devices with high surge current resistance capabilities.

[0066] The four switch units include a first switch unit 221 , a second switch unit 222 , a third switch unit 223 and a fourth switch unit 224 .

[0067] The first end of the first switch unit 221 and the first end of the third switch unit 223 are connected to the energy storage module 210, the second end of the first switch unit 221 is connected to the first end of the second switch unit 222, the second end of the third switch unit 223 is connected to the first end of the fourth switch unit 224, and the second end of the second switch unit 222 and the second end of the fourth switch unit 224 are connected to the second end of the energy storage module 210; the control end of the first switch unit 221, the control end of the second switch unit 222, the control end of the third switch unit 223, and the control end of the fourth switch unit 224 are all connected to an external control module (not shown in the figure).

[0068] The first switch unit 221 , the second switch unit 222 , the third switch unit 223 and the fourth switch unit 224 are all used to be turned on or off according to a control signal of an external control module, so as to convert the half-wave sinusoidal voltage provided by the energy storage module 210 into an AC voltage.

[0069] Exemplarily, the direct-mounted energy storage system includes a DC energy storage circuit 10, three energy storage modules 210, and three full-bridge modules. The first end of each energy storage module 210 is connected to the first end of the DC energy storage circuit 10, or to the second end of an adjacent energy storage module 210. The second end of each energy storage module 210 is connected to the second end of the DC energy storage circuit 10, or to the first end of an adjacent energy storage module 210. The DC energy storage circuit 10 is configured to provide a portion of the DC voltage to each energy storage module 210. The energy storage modules 210 then convert the received partial DC voltage into a half-wave sinusoidal voltage.

[0070] When the energy storage module 210 supplies power to the external grid 30 via the full-bridge module, the full-bridge module first uses a forward output mode. The control module controls the first switch unit 221 and the fourth switch unit 224 to conduct, while the second switch unit 222 and the third switch unit 223 remain off. The half-wave sinusoidal voltage provided by the energy storage module 210 is directly output to the external grid 30. Subsequently, when the full-bridge module uses a reverse output mode, the control module controls the second switch unit 222 and the third switch unit 223 to conduct, while the first switch unit 221 and the fourth switch unit 224 are off. At this time, the half-wave sinusoidal voltage provided by the energy storage module 210 is inverted by the full-bridge module and output to the external grid 30. This converts the half-wave sinusoidal voltage provided by the energy storage module 210 into an AC voltage that is provided to the external grid 30.

[0071] Furthermore, the switching devices of the first switch unit 221, the second switch unit 222, the third switch unit 223, and the fourth switch unit 224 are capable of withstanding high surge currents. When the energy storage system operates under rated conditions (active power P = 1, reactive power Q ≈ 0), the voltage and current at the AC output are substantially in phase. The full-bridge module switches from forward output to reverse output, or vice versa, when the DC voltage returns to zero. At this point, the AC voltage is zero and the AC current is also close to zero. At this point, the switching devices of the full-bridge module are in a zero-voltage shutdown state, and the shutdown current is very low.

[0072] The direct-mounted energy storage system provided by the present disclosure also has four-quadrant operation capability. In the four-quadrant power regulation system, when the energy storage system operates under the rated operating conditions of active power P=1 and reactive power Q≈0, there is a 90° phase difference between the AC voltage and current. When the AC voltage returns to zero, the full-bridge module performs output commutation action. At this time, the bridge arm current of the full-bridge module reaches its peak, and the switching device is turned off at this time.

[0073] For the above two situations, when the energy storage system operates under a high overload condition with active power P=3 and reactive power Q≈0, the AC current is three times the AC current under rated conditions, which is much higher than the switchable current of the switching device. However, since the switching device has the ability to withstand high surge currents, the switching device can withstand the current under high overload conditions. When the full-bridge module is in a high overload condition, the switching device can be reliably shut down during the output commutation of the full-bridge module, thereby enabling the full-bridge module to withstand a larger current. The high current tolerance capability of the entire energy storage system is enhanced due to the enhanced high current tolerance capability of the full-bridge module. Therefore, the overload resistance of the energy storage system is improved, ensuring the safe operation of the energy storage system.

[0074] In some embodiments, Figure 5 A schematic diagram of the structure of a switch unit provided in an embodiment of the present disclosure is shown in FIG. Figure 5 As shown, the switch unit includes: a plurality of switch devices 2200 and a voltage balancing circuit; the plurality of switch devices 2200 are connected in series, and the voltage balancing circuit is arranged in a one-to-one correspondence with the switch devices 2200.

[0075] For example, the multiple switch devices 2200 may include some fully controlled switch devices and some half-controlled switch devices. Half-controlled switch devices can only control conduction but not shutdown, while fully controlled switch devices can control both conduction and shutdown. Therefore, the structural design of half-controlled switch units is simpler than that of fully controlled switch devices, which results in a lower cost than that of fully controlled switch devices. This allows the full-bridge module to achieve its original functions without compromising performance while reducing circuit costs. Furthermore, since half-controlled switch devices do not need to control shutdown, the control complexity of the full-bridge module can be reduced. Furthermore, connecting multiple switch devices 2200 in series can improve the high-voltage resistance of the switch units, thereby meeting the high-voltage resistance requirements of the energy storage system.

[0076] The voltage balancing circuit includes a first resistor R1 , a first capacitor C1 , and a first diode D1 .

[0077] The first end of the first resistor R1 is connected to the first end of the first capacitor C1, the second end of the first resistor R1 is connected to the second end of the first capacitor C1, the first end of the first capacitor C1 is also connected to the negative end of the first diode D1, the positive end of the first diode D1 is connected to the first end of the switching device 2200, and the second end of the first capacitor C1 is also connected to the second end of the switching device 2200.

[0078] Specifically, when the switch device 2200 is turned off, the voltage across the switch device 2200 rises rapidly. When the voltage across the switch device 2200 is greater than the voltage of the first capacitor C1, the first diode D1 is turned on, the bridge arm current of the full-bridge module charges the first capacitor C1, and the voltage across the switch device 2200 is clamped by the first capacitor C1. When the voltage across the switch device 2200 is less than the voltage of the first capacitor C1, the first diode D1 is turned off, the first capacitor C1 is discharged through the first resistor R1, and the discharge current flows through the full-bridge module to the external power grid, allowing the first capacitor C1 to prepare for the next shutdown of the switch device 2200. As a result, the voltage balancing circuit provided by the present disclosure can achieve voltage balancing.

[0079] In some embodiments, the switching device includes an insulated-gate bipolar transistor (IGBT) or an integrated gate-commutated thyristor (IGCT) and a second diode; The positive terminal of the IGCT is connected to the negative terminal of the second diode, and the negative terminal of the IGCT is connected to the positive terminal of the second diode.

[0080] Specifically, because the IGBT has a body diode, no additional diode is required when using it as a switching device, thus reducing circuit complexity. IGCTs, on the other hand, have a stronger voltage resistance than IGBTs and can therefore be used as switching devices in high-voltage devices. When the external grid charges the energy storage module through the full-bridge module and the DC voltage just drops to 0, the current will continue to flow through a second diode connected in antiparallel with the disconnected IGCT, or through the body diode within the IGBT, until the switch unit in the other output circuit turns on. The current flowing through the second diode or body diode then flows to the energy storage module through the turned-on switch unit in the other output circuit. Furthermore, both IGBTs and IGCTs have high surge current resistance, so the full-bridge module can withstand even greater currents. This enhanced high-current tolerance of the full-bridge module also enhances the energy storage system's overload resistance, improving its operational safety.

[0081] The present disclosure also provides an energy storage device, including a direct-mounted energy storage system with high overload capacity corresponding to any of the above embodiments.

[0082] It is understandable that the energy storage device provided in the embodiment of the present application can achieve the corresponding beneficial effects of the direct-mounted energy storage system provided in the above-mentioned embodiment, which will not be described in detail here.

[0083] The above are merely specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to these embodiments, but is to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A direct-mounted energy storage system with high overload capacity, characterized in that: include: A DC tank circuit for providing a DC voltage; At least two commutation circuits, wherein a first end of the commutation circuit is connected to a first end of the DC energy storage circuit or a second end of an adjacent commutation circuit, and a second end of the commutation circuit is connected to a second end of the DC energy storage circuit or a first end of an adjacent commutation circuit; The commutation circuit includes an energy storage module and a full-bridge module, wherein the energy storage module is connected to the full-bridge module, and the output end of the full-bridge module is connected to the external power grid; the energy storage module is used to convert a portion of the DC voltage into a half-wave sinusoidal voltage, and the full-bridge module is used to convert the half-wave sinusoidal voltage into an AC voltage; Wherein, the switching device of the full-bridge module is a switching device with the ability to resist high surge current.

2. The direct-mounted energy storage system according to claim 1, characterized in that: The DC energy storage circuit includes a plurality of DC energy storage modules; the plurality of DC energy storage modules are connected in series; The DC energy storage module includes a DC energy storage unit and a first half-bridge circuit; The first end of the first half-bridge circuit is connected to the first end of the DC energy storage unit, and the second end of the first half-bridge circuit is connected to the second end of the DC energy storage unit; the control end of the first half-bridge circuit is connected to the external control module; The first half-bridge circuit is used to control the working state of the DC energy storage module according to the control signal of the external control module.

3. The direct-mounted energy storage system according to claim 1, characterized in that: The energy storage module includes a plurality of energy storage units; the plurality of energy storage units are connected in series; The energy storage unit includes an energy storage element and a second half-bridge circuit; The first end of the second half-bridge circuit is connected to the first end of the energy storage element, and the second end of the second half-bridge circuit is connected to the second end of the energy storage element; the control end of the second half-bridge circuit is connected to the external control module; The second half-bridge circuit is used to control the working state of the energy storage unit according to the control signal of the external control module.

4. The direct-mounted energy storage system according to claim 3, characterized in that: When the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls to cut out at least one energy storage unit from the plurality of energy storage units; In a case where the voltage provided by the energy storage module is less than the modulation wave voltage, the external control module controls at least one of the multiple energy storage units to be put into operation.

5. The direct-mounted energy storage system according to claim 4, characterized in that: When the voltage difference between the voltage provided by the energy storage module and the modulated wave voltage is at least half of the voltage provided by the energy storage module, the external control module determines the magnitude relationship between the voltage provided by the energy storage module and the modulated wave voltage.

6. The direct-mounted energy storage system according to claim 4, characterized in that: The energy storage unit further includes a battery management chip, which is connected to the external control module and is used to obtain the state of charge of the energy storage element; the external control module is used to sort the multiple energy storage units according to the state of charge of the energy storage element; When the energy storage module is in a charging state, The external control module controls to cut out the energy storage unit with the highest state of charge of the energy storage element from the multiple energy storage units, Alternatively, the external control module controls the energy storage unit with the lowest state of charge of the energy storage element from among the multiple energy storage units; When the energy storage module is in a discharging state, The external control module controls to cut out the energy storage unit with the lowest state of charge of the energy storage element from the plurality of energy storage units, Alternatively, the external control module controls the energy storage unit having the highest state of charge of the energy storage element to be put into use from among the multiple energy storage units.

7. The direct-mounted energy storage system according to any one of claims 1 to 6, characterized in that: The full-bridge module includes four switch units; wherein the switch devices of the switch units are switch devices with high surge current resistance capability; The four switch units include: a first switch unit, a second switch unit, a third switch unit and a fourth switch unit; The first end of the first switch unit and the first end of the third switch unit are connected to the energy storage module, the second end of the first switch unit is connected to the first end of the second switch unit, the second end of the third switch unit is connected to the first end of the fourth switch unit, and the second end of the second switch unit and the second end of the fourth switch unit are connected to the second end of the energy storage module; the control end of the first switch unit, the control end of the second switch unit, the control end of the third switch unit, and the control end of the fourth switch unit are all connected to an external control module; The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are all used to be turned on or off according to the control signal of the external control module, so that the half-wave sinusoidal voltage provided by the energy storage module is converted into the AC voltage.

8. The direct-mounted energy storage system according to claim 7, characterized in that: The switch unit includes: a plurality of switch devices and a voltage balancing circuit; the plurality of switch devices are connected in series, and the voltage balancing circuit is provided in a one-to-one correspondence with the switch devices; The voltage balancing circuit includes: a first resistor, a first capacitor and a first diode; The first end of the first resistor is connected to the first end of the first capacitor, the second end of the first resistor is connected to the second end of the first capacitor, the first end of the first capacitor is also connected to the negative end of the first diode, the positive end of the first diode is connected to the first end of the switching device, and the second end of the first capacitor is also connected to the second end of the switching device.

9. The direct-mounted energy storage system according to claim 8, characterized in that: The switching device includes an IGBT, or, IGCT and a second diode; The positive terminal of the IGCT is connected to the negative terminal of the second diode, and the negative terminal of the IGCT is connected to the positive terminal of the second diode.

10. An energy storage device, characterized in that: It comprises a direct-mounted energy storage system with high overload capacity as described in any one of claims 1 to 9.

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