A direct-hanging energy storage system with high overload capacity and an energy storage device

Abstract

The present disclosure relates to a direct-hanging energy storage system with high overload capacity and an energy storage device. 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 configured to provide a direct-current voltage; a first end of the commutation circuit is connected to a first end of the direct-current 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 direct-current energy storage circuit or a 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 to the full-bridge module, and the full-bridge module is connected to an external power grid; the energy storage module is configured to convert a part of the direct-current voltage into a half-wave sinusoidal voltage, and the full-bridge module is configured to convert the half-wave sinusoidal voltage into an alternating-current voltage. The present disclosure uses a switching device with high anti-high surge current capacity as the switching device of the full-bridge module, so that the energy storage system has enhanced ability to withstand large current, thereby improving the anti-overload capacity and ensuring the safe operation of the energy storage system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of direct current power transmission, in particular to a direct-hanging energy storage system with high overload capacity and an energy storage device. BACKGROUND

[0002] The energy storage system in the power grid can realize the storage and release of electric energy, and can play an important role in peak regulation and frequency regulation, new energy consumption, large-scale new energy transmission, etc. It is one of the important devices indispensable in the construction of new power systems. In order to ensure the safe operation of the energy storage system, the overload capacity of the energy storage system is an important indicator, so how to provide an energy storage system with high overload capacity has become a technical problem that technicians in the field need to solve. SUMMARY

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

[0004] The present disclosure provides a direct-hanging energy storage system with high overload capacity, comprising: a direct current energy storage circuit and at least two converter circuits. The direct current energy storage circuit is used to provide a direct current voltage; the first end of the converter circuit is connected with the first end of the direct current energy storage circuit or the second end of the adjacent converter circuit, and the second end of the converter circuit is connected with the second end of the direct current energy storage circuit or the first end of the adjacent converter circuit.

[0005] The converter circuit comprises an energy storage module and a full-bridge module, the energy storage module is connected with the full-bridge module, and the output end of the full-bridge module is connected with an external power grid; the energy storage module is used to convert a part of the direct current voltage into a half-wave sinusoidal voltage, and the full-bridge module is used to convert the half-wave sinusoidal voltage into an alternating current voltage.

[0006] The switching device of the full-bridge module is a switching device with high surge current resistance.

[0007] Optionally, the direct current energy storage circuit comprises a plurality of direct current energy storage modules; the plurality of direct current energy storage modules are connected in series.

[0008] The direct current energy storage module comprises a direct current energy storage unit and a first half-bridge circuit.

[0009] The first end of the first half-bridge circuit is connected with the first end of the direct current energy storage unit, and the second end of the first half-bridge circuit is connected with the second end of the direct current energy storage unit; the control end of the first half-bridge circuit is connected with an external control module.

[0010] The first half-bridge circuit is used to control the working state of the direct current energy storage module according to the control signal of the external control module.

[0011] Optionally, the energy storage module comprises a plurality of energy storage units; the plurality of energy storage units are connected in series.

[0012] The energy storage unit comprises an energy storage element and a second half-bridge circuit.

[0013] 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.

[0014] 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.

[0015] Optionally, in the case that the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls at least one energy storage unit to be cut out from the plurality of energy storage units.

[0016] In the case that 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 from the plurality of energy storage units.

[0017] Optionally, in the case that 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 judges the size relationship between the voltage provided by the energy storage module and the modulation wave voltage.

[0018] Optionally, the energy storage unit further comprises a battery management chip, the battery management chip is connected to the external control module, and the battery management chip is used to obtain the state of charge of the energy storage element; the external control module is used to sort the plurality of energy storage units according to the state of charge of the energy storage element.

[0019] In the case that the energy storage module is in a charging state,

[0020] the external control module controls at least one energy storage unit with the highest state of charge of the energy storage element to be cut out from the plurality of energy storage units,

[0021] or, the external control module controls at least one energy storage unit with the lowest state of charge of the energy storage element to be put into from the plurality of energy storage units.

[0022] In the case that the energy storage module is in a discharging state,

[0023] the external control module controls at least one energy storage unit with the lowest state of charge of the energy storage element to be cut out from the plurality of energy storage units,

[0024] or, the external control module controls at least one energy storage unit with the highest state of charge of the energy storage element to be put into from the plurality of energy storage units.

[0025] Optionally, the full-bridge module comprises four switching units; wherein the switching device of the switching unit is a switching device with high surge current resistance.

[0026] The four switch units include a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit.

[0027] The first end of the first switch unit and the first end of the third switch unit are connected with the energy storage module, the second end of the first switch unit is connected with the first end of the second switch unit, the second end of the third switch unit is connected with 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 with 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 connected with the external control module.

[0028] The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are used for being turned on or turned off according to the control signal of the external control module, so as to convert the half-wave sinusoidal signal provided by the energy storage module into an alternating current signal.

[0029] Optionally, the switch unit includes a plurality of switching devices and a voltage balancing circuit; the plurality of switching devices are connected in series, and the voltage balancing circuit is arranged in one-to-one correspondence with the switching devices.

[0030] The voltage balancing circuit includes a first resistor, a first capacitor, and a first diode.

[0031] The first end of the first resistor is connected with the first end of the first capacitor, the second end of the first resistor is connected with the second end of the first capacitor, the first end of the first capacitor is further connected with the negative electrode end of the first diode, the positive electrode end of the first diode is connected with the first end of the switching device, and the second end of the first capacitor is further connected with the second end of the switching device.

[0032] Optionally, the switching device includes an IGBT,

[0033] or,

[0034] an IGCT and a second diode.

[0035] The positive electrode end of the IGCT is connected with the negative electrode end of the second diode, and the negative electrode end of the IGCT is connected with the positive electrode end of the second diode.

[0036] The present disclosure also provides an energy storage device including any high overload capacity direct hanging energy storage system as described above.

[0037] The disclosure provides a direct-hanging energy storage system with high overload capacity and an energy storage device. 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 configured to provide a direct-current voltage; a first end of the commutation circuit is connected to a first end of the direct-current 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 direct-current energy storage circuit or a 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 to the full-bridge module, and an output end of the full-bridge module is connected to an external power grid; the energy storage module is configured to convert a part of the direct-current voltage into a half-wave sinusoidal voltage, and the full-bridge module is configured to convert the half-wave sinusoidal voltage into an alternating-current voltage and provide the alternating-current voltage to the external power grid. The switching device of the full-bridge module is a switching device with high surge current resistance. The disclosure separates the direct-current energy storage circuit and the energy storage module, so that the direct-current energy storage circuit and the energy storage module can be controlled separately, thereby improving the control flexibility of the energy storage system. In the disclosure, the switching device of the full-bridge module is a switching device with high surge current resistance, so that the full-bridge module can withstand greater current, and the entire energy storage system also has improved current resistance, thereby improving the overload resistance of the energy storage system and ensuring the safe operation of the energy storage system. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0039] Figure 1 A structural schematic diagram of a direct-hanging energy storage system provided by the embodiments of the present disclosure is provided.

[0040] Figure 2 A structural schematic diagram of another direct-hanging energy storage system provided by the embodiments of the present disclosure is provided.

[0041] Figure 3 A structural schematic diagram of another direct-hanging energy storage system provided by the embodiments of the present disclosure is provided.

[0042] Figure 4 A structural schematic diagram of another direct-hanging energy storage system provided by the embodiments of the present disclosure is provided.

[0043] Figure 5 A structural schematic diagram of a switching unit provided by the embodiments of the present disclosure is provided. DETAILED DESCRIPTION

[0044] Features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some or all of these specific details. The description of the embodiments is merely intended to provide a better understanding of the present application by showing examples of the present application.

[0045] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The embodiments will be described in detail below with reference to the accompanying drawings.

[0046] It should be noted that, in this document, the terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the elements defined by the statement "include" do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0047] It should be understood that, when describing the structure of a component, when one layer, one region is referred to as being "on" or "above" another layer, another region, it can mean being directly on or above another layer, another region, or containing other layers or regions therebetween. And if the component is turned over, the layer, the region will be "under" or "below" the other layer, the other region.

[0048] It should be understood that the term "and / or" used herein is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this document generally represents an "or" relationship between the front and rear associated objects.

[0049] In the embodiments of the present application, the term "electrically connected" can mean that two components are directly electrically connected, or that two components are electrically connected via one or more other components.

[0050] In the embodiments 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, and the first node, the second node and the third node are not an actual circuit unit.

[0051] Many modifications and variations of this application can be made in the details apparent to those skilled in the art without departing from the spirit and scope of the application. Hence, this application is to cover modifications and variations of this application provided they come within the scope of the following claims and their equivalents. It is intended that the embodiments provided by the application be combined to provide further embodiments of the application.

[0052] The disclosure provides a direct-hanging energy storage system with high overload capacity, the direct-hanging energy storage system comprising: a direct-current energy storage circuit and at least two converter circuits.

[0053] The direct-current energy storage circuit is configured to provide a direct-current voltage.

[0054] For example, the direct-current energy storage circuit can include supercapacitors, electrochemical cells, etc. The direct-current energy storage circuit can be configured to store electrical energy, and convert the stored electrical energy into a direct-current voltage and provide it externally.

[0055] The first end of the converter circuit is connected to the first end of the direct-current energy storage circuit or the second end of the adjacent converter circuit, and the second end of the converter circuit is connected to the second end of the direct-current energy storage circuit or the first end of the adjacent converter circuit.

[0056] The converter 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 an external power grid; the energy storage module is configured to convert a part of the direct-current voltage into a half-wave sinusoidal voltage, and the full-bridge module is configured to convert the half-wave sinusoidal voltage into an alternating-current voltage. The switching device of the full-bridge module is a switching device with high surge current resistance.

[0057] For example, the at least two converter circuits can include two converter circuits, and the two converter circuits can realize single-phase output of voltage.

[0058] The at least two converter circuits can also include three converter circuits, and the three converter circuits can realize three-phase output of voltage. Figure 1 A structural schematic diagram of a direct-hanging energy storage system provided by the embodiments of the disclosure is shown in Figure 1 As shown in the figure, the three converter circuits include a first converter circuit 21, a second converter circuit 22, and a third converter circuit 23.

[0059] The first end of the first converter circuit 21 is connected to the first end of the direct-current 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 direct-current energy storage circuit 10.

[0060] The energy storage module 210 and the full-bridge module 220 are connected, and the output end of the full-bridge module 220 is connected with the external power grid 30. The direct-current energy storage circuit 10 provides direct-current voltage to the first converter circuit 21, the second converter circuit 22 and the third converter circuit 23, which can be regarded as that the direct-current energy storage circuit 10 provides a part of the direct-current voltage to the first converter circuit 21, the second converter circuit 22 and the third converter circuit 23 respectively. After receiving the part of the direct-current voltage, the energy storage module 210 in each converter circuit converts the part of the direct-current voltage into a half-wave sinusoidal voltage and provides the half-wave sinusoidal voltage to the full-bridge module 220. By controlling the on-off of each switching device in the full-bridge module 220, the full-bridge module 220 outputs complete alternating-current voltage to the external power grid 30.

[0061] In the process that the energy storage system converts the direct-current voltage provided by the direct-current energy storage circuit 10 into alternating-current voltage provided to the external power grid 30, since the direct-current energy storage circuit 10 and the energy storage module 210 are respectively arranged, the control of the direct-current energy storage circuit 10 and the energy storage module 210 can be respectively realized, so that the size of the direct-current voltage provided by the direct-current energy storage circuit 10 can be controlled according to the external power grid 30 with different power demands, such as a strong power grid with a large short-circuit ratio or a weak power grid with a small short-circuit ratio, and the amplitude and phase of the half-wave sinusoidal voltage provided by the energy storage module 210 can also be controlled, so that the adjustment of the alternating-current voltage output by the full-bridge module 220 can be realized, and thus the control flexibility in the energy storage system can be improved.

[0062] In addition, the switching device used in the full-bridge module 220 has the ability to resist high inrush current, so that the full-bridge module 220 can withstand larger current, and the large current tolerance of the entire energy storage system is enhanced due to the enhanced tolerance of the full-bridge module 220 to large current, so that the overload capacity of the energy storage system is improved, and the operation safety of the energy storage system is ensured.

[0063] The direct-hanging energy storage system provided by the present disclosure also has four-quadrant operation capability to emit or absorb active power P and reactive power Q to the external power grid 30. Take the first converter circuit 21 as an example for introduction, and the principles of the second converter circuit 22 and the third converter circuit 23 are the same as that of the first converter circuit 21. Assuming that the phase voltage effective value of the alternating-current voltage is U c , the phase is δ, the phase current effective value of the alternating-current 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 converter circuit 21 is located is:

[0064]

[0065]

[0066] The output power can also be estimated according to the following formula:

[0067]

[0068]

[0069] In a three-phase symmetrical operation scenario, the output power of each phase is the same, and thus the total useful power P of the energy storage system is t The output and total reactive power Q t The output is:

[0070]

[0071]

[0072] Therefore, by controlling the amplitude and phase of the AC voltage generated by each converter circuit, the output power of the entire energy storage system can be controlled. In actual operation, instead of controlling the full-bridge module 220 to adjust the AC voltage, the output current and the voltage at the grid connection point can be used as control targets to adjust the output power of the energy storage system.

[0073] In some embodiments, Figure 2 Another structure diagram of a direct-hanging energy storage system is provided for the embodiments of the present disclosure, as shown in Figure 2 The direct-current energy storage circuit 10 includes a plurality of direct-current energy storage modules 100; the plurality of direct-current energy storage modules 100 are connected in series.

[0074] The direct-current energy storage module 100 includes a direct-current energy storage unit 110 and a first half-bridge circuit 120.

[0075] The first end of the first half-bridge circuit 120 is connected to the first end of the direct-current energy storage unit 110, and the second end of the first half-bridge circuit 120 is connected to the negative end of the direct-current energy storage unit 110; the control end of the first half-bridge circuit 120 is connected to an external control module (not shown in the figure). The first half-bridge circuit 120 is used to control the working state of the direct-current energy storage module 100 according to the control signal of the external control module.

[0076] For example, the first half-bridge circuit 120 includes a first switch Q1 and a second switch Q2. The first end of the first switch Q1 is connected to the first end of the DC energy storage unit 110, the second end of the first switch Q1 is connected to the first end of the second switch Q2, and the second end of the second switch Q2 is connected to the second end of the DC energy storage unit 110. The second end of the first switch Q1 is connected to the first end of the commutation circuit 20, or the second end of the second switch Q2 of the adjacent first half-bridge circuit 120. The second end of the second switch Q2 is connected to the second end of the commutation circuit 20, or the second end of the first switch Q1 of the adjacent first half-bridge circuit 120.

[0077] According to the control signal of the external control module, the conduction and turn-off of the first switch Q1 and the second switch Q2 are controlled, so as to realize the control of the input or output of the DC energy storage module 100. In the case that 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 series of multiple DC energy storage modules 100, so as to realize the input of the DC energy storage module 100, and at this time, the DC energy storage unit 110 can be charged or discharged according to the working state of the energy storage system. In the case that 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 series of multiple DC energy storage modules 100, so as to realize the output of the DC energy storage module 100, and 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. In the case that the first switch Q1 and the second switch Q2 are both turned off, the DC energy storage module 100 enters the latching state, and at this time, the DC energy storage unit 110 can only realize uncontrolled charging through the diode connected in reverse parallel with the first switch Q1 and the second switch Q2, and 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.

[0078] The DC energy storage module 100 further includes a filter unit 130, which can be a filter device such as a capacitor, an inductor, etc. 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 in the charging and discharging process of the DC energy storage unit 110.

[0079] In addition, the external control module can realize the adjustment of the total voltage of the DC energy storage circuit 10 by controlling the input and output 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 the DC voltage threshold. The external control module also detects the state of charge of each DC energy storage unit 110 and sorts them according to the size relationship.

[0080] In the charging state of the DC energy storage circuit 10, when the total voltage of the DC energy storage circuit 10 is greater than the DC voltage threshold, and the difference between them exceeds half of 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 cut out, 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 them exceeds half of 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 put in, thereby increasing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold.

[0081] In the discharging state of the DC energy storage circuit 10, when the total voltage of the DC energy storage circuit 10 is greater than the DC voltage threshold, and the difference between them exceeds half of 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 cut out, 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 them exceeds half of 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 put in, thereby increasing the total voltage of the DC energy storage circuit 10 and approaching the DC voltage threshold.

[0082] Therefore, the present disclosure can adjust the total voltage of the DC energy storage circuit 10 by putting in or cutting out the DC energy storage module 100 according to the comparison between the total voltage of the DC energy storage circuit 10 and the DC voltage threshold, so that the total voltage of the DC energy storage circuit 10 can change along with the DC voltage threshold, and the average DC voltage of the DC energy storage circuit 10 can be the same as the size of the DC voltage threshold. In addition, the external control module can select the DC energy storage module 100 to be put in or cut out according to the state of charge of each DC energy storage unit 110, so as to balance the state of charge of the entire DC energy storage circuit.

[0083] In some embodiments, Figure 3 Another structure schematic diagram of the direct-hanging energy storage system provided by the embodiments of the present disclosure is shown in FIG. 10. Figure 3 As shown in FIG. 10, the energy storage module 210 includes a plurality of energy storage units 211; the plurality of energy storage units 211 are connected in series.

[0084] The energy storage unit 211 includes an energy storage element 2111 and a second half-bridge circuit 2112.

[0085] The first end of the second half-bridge circuit 2112 is connected with the first end of the energy storage element 2111, and the second end of the second half-bridge circuit 2112 is connected with the second end of the energy storage element 2111; the control end of the second half-bridge circuit 2112 is connected with an external control module (not shown in the figure). The second half-bridge circuit 2112 is used for controlling the working state of the energy storage unit 211 according to the control signal of the external control module.

[0086] For example, the energy storage element 2111 can be, for example, a switched capacitor. The second half-bridge circuit 2112 includes a third switch tube Q3 and a fourth switch tube Q4. The first end of the third switch tube Q3 is connected with the first end of the energy storage element 2111, the second end of the third switch tube Q3 is connected with the first end of the fourth switch tube Q4, and the second end of the fourth switch tube Q4 is connected with the second end of the energy storage element 2111. The second end of the third switch tube Q3 is connected with the second end of the fourth switch tube Q4 of the adjacent second half-bridge circuit 2112. The second end of the fourth switch tube Q4 is connected with the second end of the third switch tube Q3 of the adjacent second half-bridge circuit 2112.

[0087] According to the control signal of the external control module, the conduction and turn-off of the third switch tube Q3 and the fourth switch tube Q4 are controlled, so as to realize the input or cut-out of the energy storage unit 211. In the case that the third switch tube Q3 is turned on and the fourth switch tube Q4 is turned off, the energy storage element 2111 is connected in the series of the plurality of energy storage units 211, so as to realize 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. In the case that 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 series of the plurality of energy storage units 211, so as to realize the cut-out 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. In the case that the third switch tube Q3 and the fourth switch tube Q4 are both turned off, the energy storage unit 211 enters the lockout state, at this time, the energy storage element 2111 can only realize the uncontrolled charging through the diode reversely connected in parallel with the third switch tube Q3 and the fourth switch tube Q4, and 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.

[0088] The pulse width modulation signal is generated by the carrier phase shift modulation technology, and the on-off of each switch tube in the second half-bridge circuit 2112 is controlled by the pulse width modulation signal, so as to be able to adjust the voltage provided by the energy storage module. N groups of triangular waves with an amplitude of 1 and a frequency of f c are taken as carriers, and the phase difference between each triangular wave is . A half-wave positive sine wave with an amplitude of and a frequency of 100 Hz is taken as a modulating wave, wherein is the peak value of the output alternating phase voltage, The voltage provided by the energy storage module 2111. By using the above-mentioned triangular wave and the modulation wave, the carrier phase-shift modulation technology is adopted to the pulse width modulation signal.

[0089] In some embodiments, when the voltage provided by the energy storage module is greater than the voltage of the modulation wave, the external control module controls at least one energy storage unit to be cut out from the plurality of energy storage units;

[0090] When the voltage provided by the energy storage module is less than the voltage of the modulation wave, the external control module controls at least one energy storage unit to be put into the plurality of energy storage units.

[0091] For example, the external control module can adjust the voltage provided by the energy storage module by controlling the putting-in and cutting-out of the energy storage units. By using the level approximation technology, the external control module stores a modulation wave, compares the voltage provided by the energy storage module with the voltage of the modulation wave, and adjusts the number of series-connected energy storage units according to the comparison result, so as to ensure 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 voltage of the modulation wave, the external control module controls at least one energy storage unit to be cut out from the plurality of energy storage units, so that the voltage of the energy storage module is reduced to approach the voltage of the modulation wave. When the voltage provided by the energy storage module is less than the voltage of the modulation wave, the external control module controls at least one energy storage unit to be put into the plurality of energy storage units, so that the voltage of the energy storage module is increased to approach the voltage of the modulation wave. Thus, 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 putting-in and cutting-out of the energy storage units, so as to generate a half-wave sinusoidal voltage formed by a plurality of level combinations.

[0092] In some embodiments, when the voltage difference between the voltage provided by the energy storage module and the voltage of the modulation wave is at least half of the voltage provided by the energy storage module, the external control module determines the size relationship between the voltage provided by the energy storage module and the voltage of the modulation wave.

[0093] 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, the input or cut-off of the energy storage unit according to the magnitude relationship between the voltage provided by the energy storage module and the modulation wave voltage will make the voltage difference between the voltage provided by the energy storage module and the modulation wave voltage larger, and it cannot be guaranteed that the voltage provided by the energy storage module can change along with the modulation wave voltage. 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 input or cut 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 less than half of the voltage provided by the energy storage module, so as to realize that the voltage provided by the energy storage module approaches the modulation wave voltage in the adjustment process, so that the voltage provided by the energy storage module can change according to the modulation wave, so as to generate a half-wave sinusoidal voltage formed by a plurality of level combinations.

[0094] In some embodiments, the energy storage unit further comprises a battery management chip connected with the external control module, the battery management chip is used to obtain the state of charge of the energy storage element; the external control module is used to sort the plurality of energy storage units according to the state of charge of the energy storage element;

[0095] In the case that the energy storage module is in a charging state,

[0096] The external control module controls to cut off the energy storage unit with the highest state of charge of the energy storage element from the plurality of energy storage units,

[0097] Or, the external control module controls to input the energy storage unit with the lowest state of charge of the energy storage element from the plurality of energy storage units;

[0098] In the case that the energy storage module is in a discharging state,

[0099] The external control module controls to cut off the energy storage unit with the lowest state of charge of the energy storage element from the plurality of energy storage units,

[0100] Or, the external control module controls to input the energy storage unit with the highest state of charge of the energy storage element from the plurality of energy storage units.

[0101] Specifically, in the case that the energy storage module is in a charging state, if one energy storage unit is to be cut off from the plurality of energy storage units, the energy storage unit with the highest state of charge of the energy storage element is selected to be cut off, so that the states of charge of the energy storage elements of the plurality of energy storage units are in a relatively uniform state, and it is avoided that one energy storage unit completes charging first due to the higher state of charge of the energy storage element thereof. If one energy storage unit is to be input from the plurality of energy storage units, the energy storage unit with the lowest state of charge of the energy storage element is selected to be input, so as to avoid that the input energy storage unit completes charging first compared with other energy storage units.

[0102] In the case that the energy storage module is in the discharging state, if one energy storage unit is to be cut out from the plurality of energy storage units, the energy storage unit with the lowest state of charge of the energy storage elements is selected to be cut out, so as to avoid that one of the energy storage units is the first to complete the discharging due to the lower state of charge of the energy storage elements. If one energy storage unit is to be put into from the plurality of energy storage units, the energy storage unit with the highest state of charge of the energy storage elements is selected to be put in, so as to avoid that the put-in energy storage unit is the first to complete the discharging compared with other energy storage units. In this way, it can be achieved that the plurality of energy storage units can complete the charging and discharging at similar times in the charging and discharging processes, so as to achieve the balance of the state of charge of the entire energy storage module.

[0103] In some embodiments, Figure 4 Another structure schematic diagram of the direct-hanging energy storage system provided by the embodiments of the present disclosure is shown in FIG. 6. Figure 4 As shown in FIG. 6, the full-bridge module includes four switching units; wherein the switching devices of the switching units are switching devices with high surge current resistance.

[0104] The four switching units include a first switching unit 221, a second switching unit 222, a third switching unit 223 and a fourth switching unit 224.

[0105] The first end of the first switching unit 221 and the first end of the third switching unit 223 are connected with the energy storage module 210, the second end of the first switching unit 221 is connected with the first end of the second switching unit 222, the second end of the third switching unit 223 is connected with the first end of the fourth switching unit 224, and the second end of the second switching unit 222 and the second end of the fourth switching unit 224 are connected with the second end of the energy storage module 210; the control end of the first switching unit 221, the control end of the second switching unit 222, the control end of the third switching unit 223 and the control end of the fourth switching unit 224 are all connected with an external control module (not shown in the figure).

[0106] The first switching unit 221, the second switching unit 222, the third switching unit 223 and the fourth switching unit 224 are all used to be turned on or turned off according to the control signal of the external control module, so as to convert the half-wave sinusoidal voltage provided by the energy storage module 210 into an alternating voltage.

[0107] For example, the direct-hanging energy storage system includes a direct-current energy storage circuit 10, three energy storage modules 210, and three full-bridge modules. The first end of the energy storage module 210 is connected with the first end of the direct-current energy storage circuit 10 or the second end of the adjacent energy storage module 210. The second end of the energy storage module 210 is connected with the second end of the direct-current energy storage circuit 10 or the first end of the adjacent energy storage module 210. The direct-current energy storage circuit 10 is used to provide partial direct-current voltage to the energy storage module 210 respectively, and the energy storage module 210 converts the partial direct-current voltage to obtain a half-wave sinusoidal voltage.

[0108] In the process that the energy storage module 210 supplies power to the external power grid 30 through the full-bridge module, the full-bridge module first adopts a forward output mode, and the control module controls the first switch unit 221 and the fourth switch unit 224 to be turned on. At this time, the second switch unit 222 and the third switch unit 223 remain off, and the half-wave sinusoidal voltage provided by the energy storage module 210 is directly output to the external power grid 30. Then, when the full-bridge module adopts a reverse output mode, the control module controls the second switch unit 222 and the third switch unit 223 to be turned on, and the first switch unit 221 and the fourth switch unit 224 are turned off. At this time, the half-wave sinusoidal voltage provided by the energy storage module 210 is output to the external power grid 30 after being inverted by the full-bridge module, thereby realizing the conversion of the half-wave sinusoidal voltage provided by the energy storage module 210 to alternating voltage to supply the external power grid 30.

[0109] In addition, 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 switching devices with high surge current resistance. When the energy storage system operates in the rated working condition of active power P = 1 and reactive power Q ≈ 0, the voltage and current at the alternating output end are substantially in phase. The action of switching the full-bridge module from forward output to reverse output, or from reverse output to forward output, occurs at the time when the voltage at the direct-current side is zero. At this time, the alternating voltage is 0, and the alternating current is close to 0. At this time, the switching devices of the full-bridge module are in zero-voltage off working condition, and the off current is very small.

[0110] The direct-hanging 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 in the rated working condition of active power P = 1 and reactive power Q ≈ 0, there is a phase difference of 90° between the alternating voltage and the current. When the alternating voltage is zero, the full-bridge module performs output commutation action. At this time, the bridge arm current of the full-bridge module reaches the peak value, and the switching devices are turned off at this time.

[0111] For the above two cases, when the energy storage system operates in a high overload working condition of active power P=3 and reactive power Q≈0, the AC current is 3 times the AC current in the rated working condition, which is much higher than the turn-off current of the switching device. However, since the switching device has the ability to withstand high surge current, the switching device can withstand the current in the high overload working condition, so that the switching device can be reliably turned off during the output commutation process of the full-bridge module in the high overload working condition, thereby enabling the full-bridge module to withstand greater current. The large current tolerance of the entire energy storage system is enhanced due to the enhanced large current tolerance of the full-bridge module, and thus the overload tolerance of the energy storage system is improved, ensuring the safe operation of the energy storage system.

[0112] In some embodiments, Figure 5 A structural diagram of a switching unit provided by the embodiment of the present disclosure is shown in Figure 5 As shown, the switching unit includes a plurality of switching devices 2200 and a voltage balancing circuit; the plurality of switching devices 2200 are connected in series, and the voltage balancing circuit is arranged one-to-one corresponding to the switching devices 2200.

[0113] For example, some fully controlled switching devices and some semi-controlled switching devices can be arranged in the plurality of switching devices 2200. The semi-controlled switching device can only control conduction and cannot control turn-off, and the fully controlled switching device can control both conduction and turn-off. Therefore, the structure of the semi-controlled switching unit is simpler than that of the fully controlled switching device, and the cost of the semi-controlled switching unit is also lower than that of the fully controlled switching device. Thus, the full-bridge module can realize the original function without affecting the performance, reduce the circuit cost, and reduce the control complexity of the full-bridge module since the semi-controlled switching device does not need to control turn-off. In addition, the plurality of switching devices 2200 are connected in series, which can improve the high-voltage resistance of the switching unit, thereby meeting the high-voltage resistance requirement of the energy storage system.

[0114] The voltage balancing circuit includes a first resistor R1, a first capacitor C1, and a first diode D1.

[0115] 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 further connected to the negative electrode end of the first diode D1, the positive electrode 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 further connected to the second end of the switching device 2200.

[0116] Specifically, when the switch device 2200 is 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, the discharge current flows to the external power grid through the full-bridge module, and the first capacitor C1 is prepared for the next off of the switch device 2200. Thus, the voltage equalization circuit provided by the present disclosure can achieve voltage equalization.

[0117] In some embodiments, the switch device comprises an Insulate-Gate Bipolar Transistor (IGBT), or an Integrated Gate-Commutated Thyristor (IGCT), and the second diode.

[0118] 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.

[0119] Specifically, since the IGBT is provided with a body diode, no additional diode is needed when the IGBT is used as the switch device, and thus the complexity of the circuit can be reduced. For the IGCT, the IGCT has stronger voltage resistance effect than the IGBT, and thus the IGCT can be used as the switch device in high-voltage devices. When the external power grid charges the energy storage module through the full-bridge module, and the direct current voltage just drops to 0, the current flows through the second diode in reverse parallel connection with the disconnected IGCT, or the body diode in the IGBT, until the switch unit in the other output loop is turned on, and the current flowing through the second diode or the body diode flows to the energy storage module through the switch unit in the other output loop. In addition, the IGBT and the IGCT both have high surge current resistance, and thus the full-bridge module can withstand larger current, and the large current resistance of the entire energy storage system is enhanced due to the enhanced large current resistance of the full-bridge module, so that the overload resistance of the energy storage system is improved, and the operation safety of the energy storage system is ensured.

[0120] The present disclosure also provides an energy storage device comprising the high-overload-capability direct-hanging energy storage system corresponding to any of the above embodiments.

[0121] It can be understood that the energy storage device provided by the embodiments of the present disclosure can achieve the corresponding beneficial effects of the direct-hanging energy storage system provided by the above embodiments, which will not be described here.

[0122] The foregoing is merely illustrative of the various implementations of the present disclosure and the general principles thereof. Numerous modifications can be made to these illustrations, and equivalents can be substituted therefor, without departing from the scope of the present disclosure. The specific embodiments commensurate with the specific application are intended to be illustrative only and not limiting of the scope of the application as set forth in the following claims.

Claims

1. A direct-hang energy storage system with high overload capability, characterized in that, The direct-current energy storage circuit is used for providing a direct-current voltage. At least two converter circuits, a first end of the converter circuit is connected with a first end of the direct-current energy storage circuit or a second end of the adjacent converter circuit, a second end of the converter circuit is connected with a second end of the direct-current energy storage circuit or a first end of the adjacent converter circuit. The converter circuit comprises an energy storage module and a full-bridge module, the energy storage module is connected with the full-bridge module, and an output end of the full-bridge module is connected with an external power grid; the energy storage module is used for converting a part of the direct-current voltage into a half-wave sinusoidal voltage, and the full-bridge module is used for converting the half-wave sinusoidal voltage into an alternating-current voltage. The switching device of the full-bridge module is a switching device with high surge current resistance. The energy storage module comprises a plurality of energy storage units; the plurality of energy storage units are connected in series. The energy storage unit comprises an energy storage element and a second half-bridge circuit. A first end of the second half-bridge circuit is connected with a first end of the energy storage element, a second end of the second half-bridge circuit is connected with a second end of the energy storage element; and a control end of the second half-bridge circuit is connected with an external control module. The second half-bridge circuit is used for controlling the working state of the energy storage unit according to a control signal of the external control module. The direct-current energy storage circuit comprises a plurality of direct-current energy storage modules; the plurality of direct-current energy storage modules are connected in series.

2. The direct-hang energy storage system of claim 1, wherein, The direct-current energy storage module comprises a direct-current energy storage unit and a first half-bridge circuit. A first end of the first half-bridge circuit is connected with a first end of the direct-current energy storage unit, a second end of the first half-bridge circuit is connected with a second end of the direct-current energy storage unit; and a control end of the first half-bridge circuit is connected with an external control module. The first half-bridge circuit is used for controlling the working state of the direct-current energy storage module according to a control signal of the external control module.

3. The direct-hanging energy storage system according to claim 1, wherein in a case where the voltage provided by the energy storage module is greater than the modulation wave voltage, the external control module controls at least one energy storage unit to be cut out 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 energy storage unit to be put into the plurality of energy storage units.

4. The direct-hanging energy storage system according to claim 3, wherein in a case where a 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 size relationship between the voltage provided by the energy storage module and the modulation wave voltage. The energy storage unit further comprises a battery management chip, the battery management chip is connected with the external control module, the battery management chip is used for acquiring a state of charge of the energy storage element; and the external control module is used for sorting the plurality of energy storage units according to the state of charge of the energy storage element.

5. The direct-hang energy storage system of claim 3, wherein, in a case where the energy storage module is in a charging state, the external control module controls the energy storage unit with the highest state of charge of the energy storage element to be cut out from the plurality of energy storage units, ​ Or, the external control module controls the energy storage element from the plurality of the energy storage unit, the lowest state of charge of the energy storage unit into the energy storage element; In the case of the energy storage module in the discharge state, The external control module controls the energy storage element from the plurality of the energy storage unit, the lowest state of charge of the energy storage unit, Or, the external control module controls the energy storage element from the plurality of the energy storage unit, the highest state of charge of the energy storage unit into the energy storage element.

6. A direct-hang energy storage system according to any one of claims 1-5, wherein, The full bridge module includes four switching units; wherein the switching device of the switching unit is a switching device with high surge current resistance; The four switching units include: a first switching unit, a second switching unit, a third switching unit and a fourth switching unit; The first end of the first switching unit and the first end of the third switching unit are connected with the energy storage module, the second end of the first switching unit is connected with the first end of the second switching unit, the second end of the third switching unit is connected with the first end of the fourth switching unit, the second end of the second switching unit and the second end of the fourth switching unit are connected with the second end of the energy storage module; the control end of the first switching unit, the control end of the second switching unit, the control end of the third switching unit and the control end of the fourth switching unit are connected with the external control module; The first switching unit, the second switching unit, the third switching unit and the fourth switching unit are used to turn on or turn 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 alternating voltage.

7. The direct-hang energy storage system of claim 6, wherein, The switching unit includes: a plurality of switching devices and a voltage balancing circuit; a plurality of the switching devices are connected in series, and the voltage balancing circuit is arranged one by one corresponding to the switching device; The voltage balancing circuit includes: a first resistor, a first capacitor and a first diode; The first end of the first resistor is connected with the first end of the first capacitor, the second end of the first resistor is connected with the second end of the first capacitor, the first end of the first capacitor is also connected with the negative electrode end of the first diode, the positive electrode end of the first diode is connected with the first end of the switching device, and the second end of the first capacitor is also connected with the second end of the switching device.

8. The direct-hanging energy storage system according to claim 7, wherein The switching device includes IGBT, Or, IGCT and the second diode; The positive electrode end of the IGCT is connected with the negative electrode end of the second diode, and the negative electrode end of the IGCT is connected with the positive electrode end of the second diode.

9. An energy storage device, characterized by, The direct-hanging energy storage system with high overload capacity includes the energy storage system according to any one of claims 1-8.

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