A energy storage converter

Abstract

The present application provides a energy storage converter. Considering the functions of each switching device and the connection relationship of this energy storage converter, it can be known that: when each switching device is turned on, each DC / AC conversion module is connected in parallel with the power grid, so current compensation can be performed on the power grid, thereby suppressing the energy fluctuation of the power grid; since each switching device can be ignored when it is turned off, it can be known from the connection relationship of this energy storage converter that: the primary side of each transformer is connected in series between the corresponding power supply end of the power grid and the corresponding connection end of the load, and each transformer forms a circuit with DC / AC conversion function with the corresponding single-phase DC / AC conversion bridge in two DC / AC conversion modules, so voltage compensation can be performed on the power grid, thereby suppressing the voltage fluctuation of the power grid; since the DC / AC conversion module and the transformer are reused in the above two processes, the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid is reduced.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a energy storage converter. Background Art

[0002] At present, in order to both suppress the energy fluctuation of the power grid and suppress the voltage fluctuation of the power grid, an energy storage converter and a dynamic voltage restorer are usually respectively arranged in the power grid.

[0003] However, the simultaneous arrangement of the energy storage converter and the dynamic voltage restorer results in a relatively high total cost for suppressing the energy fluctuation and voltage fluctuation of the power grid.

[0004] Therefore, how to reduce the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid is a technical problem to be urgently solved. Summary of the Invention

[0005] In view of this, the present invention provides an energy storage converter to reduce the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid.

[0006] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0007] The present application provides an energy storage converter, including: two DC / AC conversion modules, at least two transformers, and at least two switching devices; wherein:

[0008] The DC sides of the two DC / AC conversion modules are connected;

[0009] One end of the primary side of each transformer is connected to: the power supply end corresponding to itself on the power grid, and the other end of the primary side of each transformer is connected to: the connection end corresponding to itself on the load;

[0010] One end of the secondary side of each transformer is connected to: the AC end of the single-phase DC / AC conversion bridge corresponding to itself in one of the DC / AC conversion modules, and the other end of the secondary side of each transformer is connected to: the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the other DC / AC conversion module;

[0011] Each switching device is configured to connect both ends of the primary side and both ends of the secondary side of the transformer corresponding to itself when it is turned on.

[0012] Optionally, each switching device includes: a first switch, a second switch, and a third switch; wherein:

[0013] The first switch is connected in series between both ends of the primary side of the transformer corresponding to each switching device;

[0014] The second switch is connected in series between a pair of corresponding homologous terminals of the transformer corresponding to each of the switch devices;

[0015] The third switch is connected in series between the other pair of corresponding homologous terminals of the transformer corresponding to each of the switch devices.

[0016] Optionally, the first switch, the second switch and the third switch all include: MOS transistors or IGBTs.

[0017] Optionally, it further includes: a first channel switch and a second channel switch; wherein:

[0018] The first channel switch is connected in series between the positive poles of the DC sides of the two DC / AC conversion modules;

[0019] The second channel switch is connected in series between the negative poles of the DC sides of the two DC / AC conversion modules;

[0020] The first channel switch and the second channel switch are both used to conduct when all the switch devices are turned off, and conduct or turn off when all the switch devices are turned on.

[0021] Optionally, it further includes: a first current-limiting resistor branch and / or a second current-limiting resistor branch; wherein:

[0022] The first current-limiting resistor branch is connected in series between the positive poles of the DC sides of the two DC / AC conversion modules;

[0023] The second current-limiting resistor branch is connected in series between the negative poles of the DC sides of the two DC / AC conversion modules.

[0024] Optionally, the first channel switch and the second channel switch both include: electronic switches or mechanical switches.

[0025] Optionally, it further includes: at least four maintenance switches and at least two bypass switches; wherein:

[0026] One end of the primary side of each transformer is connected to the corresponding power supply terminal on the power grid through the maintenance switch corresponding to itself;

[0027] The other end of the primary side of each transformer is connected to the corresponding connection terminal on the load through the maintenance switch corresponding to itself;

[0028] Each bypass switch corresponds to each transformer;

[0029] One end of each bypass switch is connected to the power supply end corresponding to itself on the power grid, and the other end of each bypass switch is connected to the connection end corresponding to itself on the load.

[0030] Optionally, each bypass switch is a mechanical switch or an electronic switch;

[0031] Each maintenance switch is a mechanical switch.

[0032] Optionally, the number of levels of the conversion topology of each DC / AC conversion module is greater than or equal to 2.

[0033] Optionally, it further includes: at least four inductor branches; where:

[0034] One end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through the inductor branch corresponding to itself;

[0035] The other end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through the inductor branch corresponding to itself.

[0036] As can be seen from the above technical solutions, the present invention provides an energy storage converter. Combining the functions of each switching device and the specific connection relationship of this energy storage converter, it can be known that: when each switching device is turned on, each DC / AC conversion module is connected in parallel with the power grid. Therefore, by using the power conversion of each DC / AC conversion module, current compensation can be performed on the power grid, thereby suppressing the energy fluctuation of the power grid; in addition, since each switching device is turned off, it is equivalent to that the switching device does not play any role, that is, it can be ignored. Therefore, from the specific connection relationship of this energy storage converter, it can be known that: the primary side of each transformer is connected in series between the corresponding power supply end of the power grid and the corresponding connection end of the load, and each transformer and the corresponding single-phase DC / AC conversion bridge in two DC / AC conversion modules form a new circuit with DC / AC conversion function again. Therefore, by using the power conversion of the DC / AC conversion module, voltage compensation can be performed on the power grid, thereby suppressing the voltage fluctuation of the power grid; and because the DC / AC conversion module and the transformer are reused during the process of suppressing the voltage fluctuation and energy fluctuation of the power grid, the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid is reduced by this energy storage converter. Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0038] Figure 1 It is a schematic structural diagram of an implementation manner of the energy storage converter provided by the embodiment of the present application;

[0039] Figure 2 It is a schematic structural diagram of the DC / AC conversion module with the number of levels of the conversion topology equal to 2 provided by the embodiment of the present application;

[0040] Figure 3 It is a schematic structural diagram of the DC / AC conversion module with the number of levels of the conversion topology equal to 3 provided by the embodiment of the present application;

[0041] Figures 4 - 7 They are respectively schematic structural diagrams of another four implementation manners of the energy storage converter provided by the embodiment of the present application. Specific implementation manners

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0043] In the present application, relative 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 any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant 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 expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including an..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0044] In order to reduce the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid, the embodiment of the present application provides an energy storage converter, which is applicable to a power grid including three-phase output or single-phase output, in other words, applicable to three-phase loads or single-phase loads.

[0045] For the specific structure of the energy storage converter, please refer to Figure 1 , Figure 1 and only the first transformer T1, the second transformer T2, the third transformer T3, the first switching device 30, the second switching device 40, and the third switching device 50 are taken as examples for display; the energy storage converter specifically includes: two DC / AC conversion modules, at least two transformers, and at least two switching devices; the connection relationships between the components are specifically described as follows:

[0046] If the power grid 60 includes three-phase output, that is, the power grid 60 includes three power supply terminals, then as Figure 1 shown, the number of transformers is equal to 3, and the number of switching devices is equal to 3; if the power grid 60 includes single-phase output, that is, the power grid 60 includes two power supply terminals, then the number of transformers is equal to 2, and the number of switching devices is equal to 2.

[0047] The DC sides of the two DC / AC conversion modules are connected; taking Figure 1 as an example, the DC side of the first DC / AC conversion module 10 is connected to the DC side of the second DC / AC conversion module 20.

[0048] In practical applications, the DC sides of the two DC / AC conversion modules are respectively connected to two batteries; taking Figure 1 as an example, the DC side of the first DC / AC conversion circuit 10 is connected to the first battery B1, and the DC side of the second DC / AC conversion circuit 20 is connected to the second battery B2; alternatively, the DC sides of the two DC / AC conversion modules are connected to the same battery.

[0049] One end of the primary side of each transformer is connected to: the power supply terminal on the power grid corresponding to itself, and the other end of the primary side of each transformer is connected to: the connection terminal on the load corresponding to itself.

[0050] Taking Figure 1 as an example, one end of the primary side of the first transformer T1 is connected to the first power supply terminal AC1 of the power grid 60, that is, the connection terminal of the first phase of the power grid 60, and the other end of the primary side of the first transformer T1 is connected to the first connection terminal AC1′ of the load 70, that is, the connection terminal of the first phase of the load 70; one end of the primary side of the second transformer T2 is connected to the second power supply terminal AC2 of the power grid 60, that is, the connection terminal of the second phase of the power grid 60, and the other end of the primary side of the second transformer T2 is connected to the second connection terminal AC2′ of the load 70, that is, the connection terminal of the second phase of the load 70; one end of the primary side of the third transformer T3 is connected to the third power supply terminal AC3 of the power grid 60, that is, the connection terminal of the third phase of the power grid 60, and the other end of the primary side of the third transformer T3 is connected to the third connection terminal AC3′ of the load 70, that is, the connection terminal of the third phase of the load 70.

[0051] It should be noted that when the output of the power grid 60 is single-phase, that is, when the number of transformers and switching devices are both equal to 2, the connection relationship of the primary sides of the two transformers is the same as that of Figure 1 and can be analogously obtained, which will not be elaborated here.

[0052] One end of the secondary side of each transformer is connected to the AC terminal of the single-phase DC / AC conversion bridge corresponding to itself in a DC / AC conversion module, and the other end of the secondary side of each transformer is connected to the AC terminal of the single-phase DC / AC conversion bridge corresponding to itself in another DC / AC conversion module.

[0053] Taking Figure 1 as an example, one end of the secondary side of the first transformer T1 is connected to the AC terminal of the first single-phase DC / AC conversion bridge 11, that is, the connection terminal of the first phase on the AC side of the first DC / AC conversion module 10, and the other end of the secondary side of the first transformer T1 is connected to the AC terminal of the fourth single-phase DC / AC conversion bridge 21, that is, the connection terminal of the first phase on the AC side of the second DC / AC conversion module 20; one end of the secondary side of the second transformer T2 is connected to the AC terminal of the second single-phase DC / AC conversion bridge 12, that is, the connection terminal of the second phase on the AC side of the first DC / AC conversion module 10, and the other end of the secondary side of the second transformer T2 is connected to the AC terminal of the fifth single-phase DC / AC conversion bridge 22, that is, the connection terminal of the second phase on the AC side of the second DC / AC conversion module 20; one end of the secondary side of the third transformer T3 is connected to the AC terminal of the third single-phase DC / AC conversion bridge 13, that is, the connection terminal of the third phase on the AC side of the first DC / AC conversion module 10, and the other end of the secondary side of the third transformer T3 is connected to the AC terminal of the sixth single-phase DC / AC conversion bridge 23, that is, the connection terminal of the third phase on the AC side of the second DC / AC conversion module 20.

[0054] It should be noted that when the output of the power grid 60 is single-phase, that is, when the number of transformers and switching devices are both equal to 2, the connection relationship of the secondary sides of the two transformers is the same as that of Figure 1 and can be analogously obtained, which will not be elaborated here.

[0055] Optionally, the number of levels of the conversion topology of each DC / AC conversion module can all be equal to 2, as shown in Figure 2 ( Figure 2 only taking the three-phase output on the AC side as an example for display), or can all be equal to 3, as shown in Figure 3 ( Figure 3 only taking the three-phase output on the AC side as an example for display). In practical applications, it includes but is not limited to this, and no specific limitation is made here. As long as the number of levels of the conversion topology of each DC / AC conversion module is greater than or equal to 2, it is within the protection scope of this application and can be determined according to specific circumstances.

[0056] Each switching device is configured to connect both ends of the primary side and both ends of the secondary side of the transformer corresponding to itself when it is turned on.

[0057] Take Figure 1 as an example. When the first switching device 30 is turned on, it connects both ends of the primary side and both ends of the secondary side of the first transformer T1, that is, it connects the first power supply terminal AC1 of the power grid 60 to the first connection terminal AC1' of the load 70, and the connection points are respectively connected to the connection terminal of the first phase on the AC side of the first DC / AC conversion module 10 and the connection terminal of the first phase on the AC side of the second DC / AC conversion module 20; when the second switching device 40 is turned on, it connects both ends of the primary side and both ends of the secondary side of the second transformer T2, that is, it connects the second power supply terminal AC2 of the power grid 60 to the second connection terminal AC2' of the load 70, and the connection points are respectively connected to the connection terminal of the second phase on the AC side of the first DC / AC conversion module 10 and the connection terminal of the second phase on the AC side of the second DC / AC conversion module 20; when the third switching device 50 is turned on, it connects both ends of the primary side and both ends of the secondary side of the third transformer T3, that is, it connects the third power supply terminal AC3 of the power grid 60 to the third connection terminal AC3' of the load 70, and the connection points are respectively connected to the connection terminal of the third phase on the AC side of the first DC / AC conversion module 10 and the connection terminal of the third phase on the AC side of the second DC / AC conversion module 20.

[0058] It can be seen from Figure 1 that when all three switching devices are turned on, the AC sides of the first DC / AC conversion module 10 and the second DC / AC conversion module 20 are both connected in parallel with the power grid 60. Therefore, by controlling the power conversion of the first DC / AC conversion module 10 and the second DC / AC conversion module 20, current compensation can be performed on the power grid 60, thereby suppressing the energy fluctuation of the power grid 60.

[0059] It should be noted that the power conversion processes of the first DC / AC conversion module 10 and the second DC / AC conversion module 20 are already very mature in the prior art and will not be elaborated here.

[0060] It can be further deduced from this that when each switching device is turned on, the AC sides of the two DC / AC conversion modules are both connected in parallel with the power grid; therefore, by controlling the power conversion of the two DC / AC conversion modules, the two DC / AC conversion modules can perform current compensation on the power grid 60, thereby suppressing the energy fluctuation of the power grid 60.

[0061] It should be noted that, under normal circumstances, when current fluctuations occur in the power grid 60, all the switching devices are turned on, and the energy storage converter compensates the current of the power grid 60 to suppress the energy fluctuations of the power grid 60.

[0062] Since each switching device being turned off is equivalent to the switching device not playing any role, that is, it can be ignored, the connection relationship between the primary and secondary sides of each transformer remains unchanged.

[0063] Since the connection relationship between the primary and secondary sides of each transformer has been described in detail above by taking Figure 1 as an example, it will not be elaborated here.

[0064] When the first switching device 30 is turned off, taking the first power supply end AC1 of the power grid 60 and the first connection end AC1′ of the load 70 in Figure 1 as an example, assuming that the AC end of the first single-phase DC / AC conversion bridge 11 is in the positive half cycle, the current flow path is as shown in Figure 1 : The flow path on the power grid side is: the first power supply end AC1 of the power grid 60, the primary side of the first transformer T1, the first connection end AC1′ of the load 70; the flow path on the energy storage converter side is: the positive pole of the DC side of the first DC / AC conversion module 10, the first single-phase DC / AC conversion bridge 11, the secondary side of the first transformer T1, the fourth single-phase DC / AC conversion bridge 21, the negative pole of the DC side of the second DC / AC conversion module 20, the positive pole of the DC side of the first DC / AC conversion module 10; thus controlled, the first single-phase DC / AC conversion bridge 11, the first transformer T1, and the fourth single-phase DC / AC conversion bridge 21 re-form a new circuit with DC / AC conversion function.

[0065] Therefore, by controlling the power conversion of the new circuit, the voltage of the secondary side of the first transformer T1 can be controlled, that is, the voltage of the primary side of the first transformer T1 can also be controlled; and since the primary side of the first transformer T1 is connected in series between the power grid 60 and the load 70, the voltage of the first connection end AC1′ of the load 70 is equal to the sum of the output voltage of the first power supply end AC1 of the power grid 60 and the voltage of the primary side of the first transformer T1, so that the power grid 60 can be voltage-compensated, that is, when the output voltage of the first power supply end AC1 of the power grid 60 suddenly changes, the voltage of the first connection end AC1′ of the load 70 can be ensured to be within a reasonable range, and further the voltage fluctuations of the first power supply end AC1 of the power grid 60 can be suppressed, ensuring the power supply quality of the load 70 and achieving the purpose of dynamic voltage compensation.

[0066] It should be noted that the power conversion process of the formed new circuit is the same as that of the first DC / AC conversion module 10, and will not be elaborated here.

[0067] It can be further deduced that: when each switching device is turned off, the primary side of each transformer is connected in series between the corresponding power supply terminal of the power grid 60 and the corresponding connection terminal of the load 70. Moreover, the secondary side of each transformer and the corresponding single-phase DC / AC conversion bridge in the two DC / AC conversion modules re-form a new circuit with DC / AC conversion function. Therefore, by controlling the power conversion of the new circuit, the voltage of the secondary side of the corresponding transformer can be controlled, that is, the voltage of the primary side of the corresponding transformer can be controlled, so as to compensate the voltage of the power grid 60. That is, when the voltage of the power grid 60 suddenly changes, the voltage of the load 70 can be ensured to be within a reasonable range, and then the voltage fluctuation of the power grid 60 can be suppressed, the power supply quality of the load 70 can be ensured, and the purpose of dynamic voltage compensation can be achieved.

[0068] It should be noted that usually, when the current of the power grid 60 fluctuates, all the switching devices are turned off, and the energy storage converter compensates the voltage of the power grid 60 to suppress the voltage fluctuation of the power grid 60.

[0069] As can be seen from the above, when each switching device is turned on, the power conversion of the two DC / AC conversion modules can be used to suppress the energy fluctuation of the power grid 60. When each switching device is turned off, the power conversion of all the newly formed circuits can be used to suppress the voltage fluctuation of the power grid. Since the DC / AC conversion modules and transformers are reused in the process of suppressing the voltage fluctuation and energy fluctuation of the power grid 60, the total cost of suppressing the energy fluctuation and voltage fluctuation of the power grid 60 is reduced for this energy storage converter.

[0070] In addition, this energy storage converter integrates the function of suppressing the energy fluctuation of the power grid 60 and the function of suppressing the voltage fluctuation of the power grid 60 by time-sharing reuse of the corresponding devices, improving the utilization rate of the equipment.

[0071] In practical applications, when the energy storage converter compensates the current of the power grid 60, there are two control modes for each DC / AC conversion module, one is the active power control mode, and the other is the reactive power control mode.

[0072] Using the following formula, the abc / dq transformation is performed on the three-phase voltages Ua, Ub, and Uc of the power grid to obtain the components Ud and Uq in the dq rotating coordinate system.

[0073]

[0074] Using the following formula, the abc / dq transformation is performed on the three-phase currents Ia, Ib, and Ic on the AC side of the DC / AC conversion module to obtain the components Id and Iq in the dq rotating coordinate system.

[0075]

[0076] The power equation can be obtained as follows:

[0077] P = U d * I d + U q * I q

[0078] Q = U q * I d - U d * I q

[0079] In the formula, P is the active power, Q is the reactive power, and ω is the system angular frequency; if the rotation angle of ωt is consistent with the phase angle of the three-phase voltage of the power grid, then Uq is zero.

[0080] It can be seen from this that the active control and reactive control of the DC / AC conversion module are realized by separately controlling the magnitudes of Id and Iq.

[0081] It should be noted that the active control mode and reactive control mode of the DC / AC conversion module are already very mature in the prior art, and will not be described in detail here.

[0082] Another embodiment of the present application provides an implementation manner of the switching device, which can be applied to each switching device; the specific structure of this implementation manner is as Figure 1 shown, and specifically includes: a first switch S1, a second switch S2, and a third switch S3; the connection relationships between the components are specifically as described below:

[0083] The first switch S1 is connected in series between the two ends of the primary side of the transformer corresponding to each switching device; taking Figure 1 the first switching device 30 in

[0084] as an example, the first switch S1 is connected in series between the two ends of the primary side of the first transformer T1. Figure 1 The second switch S2 is connected in series between a pair of homologous ends of the transformer corresponding to each switching device; taking

[0085] the first switching device 30 in Figure 1Taking the first switching device 30 in [the text] as an example, the third switch S3 is connected in series between another pair of corresponding ends of the first transformer T1. Assuming that the second end of the primary side and the second end of the secondary side of the first transformer T1 are another pair of corresponding ends, then the third switch S3 is connected in series between the second end of the primary side and the second end of the secondary side of the first transformer T1.

[0086] When the first switch S1, the second switch S2, and the third switch S3 are all turned off, the corresponding switching device is turned off. When the first switch S1, the second switch S2, and the third switch S3 are all turned on, the corresponding switching device is turned on.

[0087] Optionally, the first switch S1, the second switch S2, and the third switch S3 can all include MOS transistors, or they can all include IGBTs. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0088] The above is only a specific implementation manner of the switching device. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0089] Another embodiment of this application provides another implementation manner of the energy storage converter. Its specific structure can be referred to Figure 4 , Figure 4 only shown on the basis of Figure 1 . This implementation manner of the energy storage converter, on the basis of the above implementation manner, further includes: a first channel switch St1 and a second channel switch St2; the connection relationship between this device and other devices is specifically described as follows:

[0090] The first channel switch St1 is connected in series between the positive poles of the DC sides of two DC / AC conversion modules; the second channel switch St2 is connected in series between the negative poles of the DC sides of two DC / AC conversion modules; taking Figure 4 as an example, the first channel switch St1 is connected in series between the positive pole of the DC side of the first DC / AC conversion module 10 and the positive pole of the DC side of the second DC / AC conversion module 20, and the second channel switch St2 is connected in series between the negative pole of the DC side of the first DC / AC conversion module 10 and the negative pole of the DC side of the second DC / AC conversion module 20.

[0091] Both the first channel switch St1 and the second channel switch St2 are used to conduct when all the switching devices are turned off, so that the DC sides of the two DC / AC conversion modules are connected in parallel; both the first channel switch St1 and the second channel switch St2 are also used to conduct or turn off when all the switching devices are turned on.

[0092] When all the switching devices are turned on, that is, when the energy storage converter compensates the current of the power grid 60, if both the first-channel switch St1 and the second-channel switch St2 are turned on, the two DC / AC conversion modules operate in parallel. If both the first-channel switch St1 and the second-channel switch St2 are turned off, the two DC / AC conversion modules operate independently.

[0093] Optionally, both the first-channel switch St1 and the second-channel switch St2 can be mechanical switches or electronic switches. There is no specific limitation here and it can be determined according to the specific situation, and both are within the protection scope of this application.

[0094] Optionally, if both the first-channel switch St1 and the second-channel switch St2 are electronic switches, both the first-channel switch St1 and the second-channel switch St2 can be MOS transistors or IGBTs. In practical applications, including but not limited to this, there is no specific limitation here and it can be determined according to the specific situation, and both are within the protection scope of this application.

[0095] In this embodiment, by adding two channel switches, when the energy storage converter compensates the current of the power grid 60, the two DC / AC conversion modules can operate independently or in parallel, thus increasing various options and being applicable to more application scenarios.

[0096] Another embodiment of this application also provides another implementation manner of the energy storage converter. For its specific structure, reference can be made to Figure 5 , Figure 5 Only taking Figure 4 as an example including the first current-limiting resistor branch 80 and the second current-limiting resistor branch 90 for display. On the basis of the previous embodiment, this implementation manner of the energy storage converter further includes: the first current-limiting resistor branch 80, and / or, the second current-limiting resistor branch 90; the connection relationship between this device and other devices is specifically described as follows:

[0097] The first current-limiting resistor branch 80 is connected in series between the positive poles of the DC sides of the two DC / AC conversion modules; the second current-limiting resistor branch 90 is connected in series between the negative poles of the DC sides of the two DC / AC conversion modules; taking Figure 4 as an example, the first current-limiting resistor branch 80 is connected in series between the positive pole of the DC side of the first DC / AC conversion module 10 and the positive pole of the DC side of the second DC / AC conversion module 20, and the second current-limiting resistor branch 90 is connected in series between the negative pole of the DC side of the first DC / AC conversion module 10 and the negative pole of the DC side of the second DC / AC conversion module 20 through St2.

[0098] Among them, the first current-limiting resistor branch 80 includes at least one resistor. If the number of resistors is greater than 1, all the resistors are connected in series and parallel, and the two ends of the formed branch are respectively used as the two ends of the first current-limiting resistor branch 80. If the number of resistors is equal to 1, the two ends of the resistor are respectively used as the two ends of the first current-limiting resistor branch 80. For example, as Figure 5 shown by the resistor R1 in

[0099] The second current-limiting resistor branch 90 includes at least one resistor. If the number of resistors is greater than 1, all the resistors are connected in series and parallel, and the two ends of the formed branch are respectively used as the two ends of the second current-limiting resistor branch 90. If the number of resistors is equal to 1, the two ends of the resistor are respectively used as the two ends of the second current-limiting resistor branch 90. For example, as Figure 5 shown by the resistor R2 in

[0100] In this embodiment of the energy storage converter, by adding the first current-limiting resistor branch and / or the second current-limiting resistor branch, the current between the DC sides of the two DC / AC conversion modules is limited, so that damage to the energy storage converter can be avoided.

[0101] Another embodiment of the present application provides another implementation manner of the energy storage converter. For its specific structure, reference can be made to Figure 6 , Figure 6 Only on the basis of Figure 5 , taking the example of including the first maintenance switch Sj1, the second maintenance switch Sj2, the third maintenance switch Sj3, the fourth maintenance switch Sj4, the fifth maintenance switch Sj5, the sixth maintenance switch Sj6, the first bypass switch Sp1, the second bypass switch Sp2, and the third bypass switch Sp3, this implementation manner of the energy storage converter further includes, on the basis of the above implementation manner: at least four maintenance switches and at least two bypass switches; the connection relationships between the components are specifically described as follows:

[0102] One end of the primary side of each transformer is connected to the corresponding power supply end on the power grid 60 through the maintenance switch corresponding to itself; the other end of the primary side of each transformer is connected to the corresponding connection end on the load 70 through the maintenance switch corresponding to itself.

[0103] Taking Figure 6For example, one end of the primary side of the first transformer T1 is connected to the first power supply terminal AC1 of the power grid 60 through the first maintenance switch Sj1, and the other end of the primary side of the first transformer T1 is connected to the first connection terminal AC1' of the load 70 through the second maintenance switch Sj2; one end of the primary side of the second transformer T1 is connected to the second power supply terminal AC2 of the power grid 60 through the third maintenance switch Sj3, and the other end of the primary side of the second transformer T2 is connected to the second connection terminal AC2' of the load 70 through the fourth maintenance switch Sj4; one end of the primary side of the third transformer T3 is connected to the third power supply terminal AC3 of the power grid 60 through the fifth maintenance switch Sj5, and the other end of the primary side of the third transformer T3 is connected to the third connection terminal AC3' on the load 70 through the sixth maintenance switch Sj6.

[0104] It should be noted that when the output of the power grid 60 is single-phase, that is, when the number of transformers and switch devices is both equal to 2, the connection relationship between the primary sides of the two transformers and the corresponding maintenance switches is the same as that of Figure 6 which can be analogously obtained and will not be elaborated here.

[0105] Among them, each maintenance switch is a mechanical switch so that the staff can observe the switch state of the maintenance switch.

[0106] Optionally, if each maintenance switch is an electronic switch, each maintenance switch can be an MOS transistor or an IGBT. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific circumstances, all within the protection scope of this application.

[0107] Each bypass switch corresponds to each transformer one by one; one end of each bypass switch is connected to the power supply terminal on the power grid 60 corresponding to itself, and the other end of each bypass switch is connected to the connection terminal on the load 70 corresponding to itself.

[0108] Take Figure 6 as an example. One end of the first bypass switch Sp1 is connected to the first power supply terminal AC1 of the power grid 60, and the other end of the first bypass switch Sp1 is connected to the first connection terminal AC1' of the load 70; one end of the second bypass switch Sp2 is connected to the second power supply terminal AC2 of the power grid 60, and the other end of the second bypass switch Sp2 is connected to the second connection terminal AC2' of the load 70; one end of the third bypass switch Sp3 is connected to the third power supply terminal AC3 of the power grid 60, and the other end of the third bypass switch Sp3 is connected to the third connection terminal AC3' of the load 70.

[0109] It should be noted that when the output of the power grid 60 is single-phase, that is, when the number of bypass switches is equal to 2, the connection relationship between the two bypass switches is the same as that of Figure 6 which can be analogously obtained and will not be elaborated here.

[0110] Optionally, each bypass switch can be a mechanical switch or all can be electronic switches. There is no specific limitation here and it can be determined according to the specific situation, and all are within the protection scope of this application.

[0111] Optionally, if each bypass switch is an electronic switch, then each bypass switch can be all MOS transistors or all IGBTs. In practical applications, including but not limited to this, there is no specific limitation here and it can be determined according to the specific situation, and all are within the protection scope of this application.

[0112] Each maintenance switch is used to turn off when the energy storage converter fails or needs to be maintained, and turn on when the energy storage converter does not fail or does not need to be maintained; each bypass switch is used to turn on when the energy storage converter fails or needs to be maintained, and turn off when the energy storage converter does not fail or does not need to be maintained.

[0113] It should be noted that the failure of the energy storage converter can refer to: the first switch in the switching device has a short-circuit fault.

[0114] Take Figure 6 as an example. When the energy storage converter fails or needs to be maintained, the first maintenance switch Sj1, the second maintenance switch Sj2, the third maintenance switch Sj3, the fourth maintenance switch Sj4, the fifth maintenance switch Sj5, and the sixth maintenance switch Sj6 are all turned off, and the first bypass switch Sp1, the second bypass switch Sp2, and the third bypass switch Sp3 are all turned on.

[0115] In this embodiment, since when the energy storage converter fails or needs to be maintained, each maintenance switch is turned off and each bypass switch is turned on, the power grid is connected to the load through each bypass switch, and the energy storage converter is no longer connected to the power grid 60 and the load 70, so that the load 70 can be ensured not to lose power, that is, the load 70 can continue to work normally, or, on the premise of ensuring that the load 70 does not lose power, the energy storage converter can be repaired or replaced.

[0116] Another embodiment of this application provides another implementation manner of the energy storage converter. For its specific structure, reference can be made to Figure 7 , Figure 7 Only on the basis of Figure 6 only the first inductance branch 01, the second inductance branch 02, the third inductance branch 03, the fourth inductance branch 04, the fifth inductance branch 05, and the sixth inductance branch 06 are shown. This implementation manner of the energy storage converter further includes: at least four inductance branches on the basis of the above implementation manner; the connection relationships between the components are specifically described as follows:

[0117] One end of the secondary side of each transformer is connected to the AC terminal of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through an inductance branch corresponding to itself; the other end of the secondary side of each transformer is connected to the AC terminal of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through an inductance branch corresponding to itself.

[0118] Take Figure 7 as an example. One end of the secondary side of the first transformer T1 is connected to the connection end of the first phase on the AC side of the first DC / AC conversion module 10 through the first inductance branch 01, and the other end of the secondary side of the first transformer T1 is connected to the connection end of the first phase on the AC side of the second DC / AC conversion module 20 through the second inductance branch 02; one end of the secondary side of the second transformer T2 is connected to the connection end of the second phase on the AC side of the first DC / AC conversion module 10 through the third inductance branch 03, and the other end of the secondary side of the second transformer T2 is connected to the connection end of the second phase on the AC side of the second DC / AC conversion module 20 through the fourth inductance branch 04; one end of the secondary side of the third transformer T3 is connected to the connection end of the third phase on the AC side of the first DC / AC conversion module 10 through the fifth inductance branch 05, and the other end of the secondary side of the third transformer T3 is connected to the connection end of the third phase on the AC side of the second DC / AC conversion module 20 through the sixth inductance branch 06.

[0119] Among them, each inductance branch includes at least one inductor. If the number of inductors is greater than 1, all inductors are connected in series and parallel, and the two ends of the formed branch are respectively used as the two ends of the corresponding inductance branch; if the number of inductors is equal to 1, the two ends of the inductor are respectively used as the two ends of the connected inductance branch. For example, as shown by the inductor L in Figure 7 .

[0120] Regarding the above description of the disclosed embodiments, the features described in each embodiment in this specification can be replaced or combined with each other, enabling those skilled in the art to implement or use this application. The above is only a preferred embodiment of the present invention and does not impose any formal limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the protection of the technical solution of the present invention.

Claims

1. A energy storage converter, characterized in that, The structure of the energy storage converter includes: two DC / AC conversion modules, at least two transformers, and at least two switching devices; where: The DC sides of the two DC / AC conversion modules are connected. One end of the primary side of each transformer is connected to the power supply end corresponding to itself on the power grid, and the other end of the primary side of each transformer is connected to the connection end corresponding to itself on the load. One end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in one of the DC / AC conversion modules, and the other end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the other DC / AC conversion module. Each switching device is used to connect the two ends of the primary side and the two ends of the secondary side of the transformer corresponding to itself when it is turned on. Each switching device includes: a first switch, a second switch, and a third switch; where: the first switch is connected in series between the two ends of the primary side of the transformer corresponding to each switching device; the second switch is connected in series between a pair of corresponding same-named ends of the transformer corresponding to each switching device; the third switch is connected in series between the other pair of corresponding same-named ends of the transformer corresponding to each switching device. When each switching device is turned on, the AC sides of the two DC / AC conversion modules are connected in parallel with the power grid; by controlling the power conversion of the two DC / AC conversion modules, the two DC / AC conversion modules perform current compensation on the power grid to suppress the energy fluctuation of the power grid. When each switching device is turned off, the primary side of each transformer is connected in series between the corresponding power supply end of the power grid and the corresponding connection end of the load, and the secondary side of each transformer and the corresponding single-phase DC / AC conversion bridge in the two DC / AC conversion modules re-form a new circuit with DC / AC conversion function. By controlling the power conversion of the new circuit, the voltage of the secondary side of the corresponding transformer is controlled, and the voltage of the primary side of the corresponding transformer is controlled to perform voltage compensation on the power grid to ensure that the voltage of the load is within a reasonable range and suppress the voltage fluctuation of the power grid when the voltage of the power grid suddenly changes.

2. The energy storage converter according to claim 1, wherein The first switch, the second switch, and the third switch all include: MOS transistors or IGBTs.

3. The energy storage converter according to any one of claims 1 to 2, characterized in that It also includes: A first channel switch and a second channel switch; where: The first channel switch is connected in series between the positive poles of the DC sides of the two DC / AC conversion modules. The second channel switch is connected in series between the negative poles of the DC sides of the two DC / AC conversion modules. The first channel switch and the second channel switch are both used to turn on when all the switching devices are turned off, and can be turned on or off when all the switching devices are turned on.

4. The energy storage converter according to claim 3, wherein It also includes: A first current-limiting resistor branch and / or a second current-limiting resistor branch; where: The first current-limiting resistor branch is connected in series between the positive poles of the DC sides of the two DC / AC conversion modules. The second current-limiting resistor branch is connected in series between the negative poles of the DC sides of the two DC / AC conversion modules.

5. The energy storage converter according to claim 3, characterized in that Both the first channel switch and the second channel switch include: an electronic switch or a mechanical switch.

6. The energy storage converter according to any one of claims 1 to 2, characterized in that, It further includes: At least four maintenance switches and at least two bypass switches; where: One end of the primary side of each transformer is connected to the corresponding power supply end on the power grid through the maintenance switch corresponding to itself; The other end of the primary side of each transformer is connected to the corresponding connection end on the load through the maintenance switch corresponding to itself; Each bypass switch corresponds to each transformer; One end of each bypass switch is connected to the corresponding power supply end on the power grid, and the other end of each bypass switch is connected to the corresponding connection end on the load.

7. The energy storage converter according to claim 6, wherein Each bypass switch is a mechanical switch or an electronic switch; Each maintenance switch is a mechanical switch.

8. The energy storage converter according to any one of claims 1 to 2, characterized in that, The level number of the conversion topology of each DC / AC conversion module is greater than or equal to 2.

9. The energy storage converter according to any one of claims 1 to 2, characterized in that, It further includes: At least four inductor branches; where: One end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through the inductor branch corresponding to itself; The other end of the secondary side of each transformer is connected to the AC end of the single-phase DC / AC conversion bridge corresponding to itself in the corresponding DC / AC conversion module through the inductor branch corresponding to itself.

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