Inverter architecture allowing bus to be externally connected and control method

Abstract

The invention discloses an inverter architecture allowing a bus to be externally connected and a control method, the inverter architecture comprises a communication module and a circuit architecture of a power generation system, the communication module is preset with a communication interface, and a bus interface is reserved at a direct current bus position of the circuit architecture; the energy storage module is suitable for being respectively connected with the communication interface and the bus interface so as to access the inverter architecture; the communication module is suitable for performing charging and discharging control on the energy storage module through the communication interface; the energy storage module is suitable for charging and discharging through the bus interface. The control method is used for controlling the inverter architecture. The inverter architecture has the beneficial effects that the bus of the circuit architecture is allowed to be externally connected, and the inverter architecture can be used as a power generation system or an energy storage power generation system according to whether the energy storage module is connected or not, so that the whole system structure is very flexible.

Description

Technical Field

[0001] The present application relates to the field of renewable energy power generation, and in particular to an inverter architecture and control method that allows external bus connection. Background Art

[0002] Taking photovoltaic power generation as an example, the existing inverter systems mainly include photovoltaic power generation systems and photovoltaic storage power generation systems. The former directly uses the electric energy generated by photovoltaics as the power supply for the load; the latter is equipped with an energy storage module on the basis of the former, which can store the excess electric energy in the photovoltaic power generation process, so that the stored electric energy can be used to power the load when the photovoltaic components are not working.

[0003] The architecture and control logic used by photovoltaic power generation systems and photovoltaic storage power generation systems in the prior art are different; if users need to store excess electricity after purchasing a photovoltaic power generation system, they often need to repurchase a complete photovoltaic storage power generation system, which will increase the user's purchase cost. That is, the prior art lacks a flexible architecture that can simultaneously match photovoltaic power generation systems and photovoltaic storage power generation systems. Summary of the invention

[0004] One of the objectives of the present application is to provide an inverter architecture that allows external connection of a busbar and can solve at least one of the defects in the above-mentioned background technology.

[0005] Another object of the present application is to provide a control method for an inverter architecture that allows external connection of a busbar and can solve at least one of the defects in the above-mentioned background technology.

[0006] In order to achieve at least one of the above-mentioned purposes, the technical solution adopted in the present application is: an inverter architecture that allows bus external connection, including a communication module and a circuit architecture of a power generation system, the communication module is preset with a communication interface, and the DC bus position of the circuit architecture is reserved with a bus interface; the energy storage module is suitable for being connected to the communication interface and the bus interface respectively to access the inverter architecture; the communication module is suitable for controlling the charging and discharging of the energy storage module through the communication interface; the energy storage module is suitable for charging and discharging through the bus interface.

[0007] Preferably, the bus interface includes a positive bus interface and a negative bus interface respectively connected to the positive and negative busbars; the energy storage module is suitable for being connected to the positive bus interface and the negative bus interface respectively through the connecting end, and a plurality of the energy storage modules are connected in parallel with each other.

[0008] Preferably, the bus interface includes a positive bus interface and a negative bus interface respectively connected to the positive and negative busbars, and a bus midpoint interface connected to the bus midpoint; when the number of the connected energy storage modules is an even number, the energy storage modules are divided into two groups of equal number; the energy storage modules of one group are connected in parallel to the positive bus interface and the bus midpoint interface through a connecting end, and the energy storage modules of the other group are connected in parallel to the bus midpoint interface and the negative bus interface through a connecting end; when the number of the connected energy storage modules is an odd number, one of the energy storage modules is connected to the positive bus interface and the negative bus interface respectively through a connecting end, and the remaining energy storage modules are divided into two groups of equal number to be connected in parallel to the positive bus interface and the bus midpoint interface, and the bus midpoint interface and the negative bus interface respectively.

[0009] Preferably, the communication module includes a communication bus, a processor and a first control unit; the processor and the first control unit are both connected to the communication bus, so that the processor sends instructions for controlling each power unit in the circuit architecture to the first control unit through the communication bus; when the energy storage module is connected, it is connected to the communication interface through the second control unit, and the processor is suitable for sending charging and discharging instructions to the power unit of the energy storage module through the communication bus according to feedback data of the first control unit.

[0010] Preferably, the power unit of the circuit architecture includes a DC / DC unit and a DC / AC unit, and the first control unit includes a first control chip and a second control chip; the first control chip is suitable for issuing control instructions to the DC / DC unit and receiving the generated power fed back by the DC / DC unit; the second control chip is suitable for issuing control instructions to the DC / AC unit.

[0011] A control method for the inverter architecture that allows bus external connection, comprising the following steps: when the circuit architecture is not connected to an energy storage module, the DC / DC unit of the circuit architecture performs MPPT power control, and the DC / AC unit of the circuit architecture performs bus voltage maintenance control; when the circuit architecture is connected to the energy storage module, the control modes of the DC / DC unit and the DC / AC unit remain unchanged, and the Bi-DC / DC unit of the energy storage module performs charging and discharging control according to the system scheduling requirements and the output power limitation of the power generation unit in the circuit architecture.

[0012] Preferably, the control loops of the DC / DC unit and the DC / AC unit both include a voltage outer loop and a current inner loop; the control of the DC / DC unit includes the following process: the voltage outer loop uses the comparison result of the MPPT tracking result with the output voltage of the power generation unit as the input of the current inner loop, and then the current inner loop generates a control signal for driving the DC / DC unit according to the comparison of the output of the voltage outer loop with the output current of the power generation unit; the control of the DC / AC unit includes the following process: the voltage outer loop uses the comparison result of the bus voltage with the set command value as the input of the current inner loop, and at the same time uses the output current of the DC / AC unit and the output of the grid-side phase-locked loop as the input of the current inner loop, and then modulates the output of the current inner loop after passing through the current inner loop to obtain a control signal for controlling the DC / AC unit.

[0013] Preferably, the charging and discharging control of the Bi-DC / DC unit includes the following process: according to the system scheduling demand P B_ref and the power generation power P of the power generation unit in the circuit architecture PV The charge and discharge power P of the energy storage module is calculated based on the limit B ; According to the obtained charge and discharge power P B Calculate the bus current command I required by the current inner loop B * , and then in the current inner loop through the bus current command I B * and the operating current I of the energy storage module B A control signal for driving the Bi-DC / DC unit is obtained.

[0014] Preferably, the discharge direction of the energy storage module is defined as positive, and the charge and discharge power P of the energy storage module is defined as positive. B The calculation formula is as follows: When the energy storage module is charging, P B =-min(P B_ref , P PV ); When the energy storage module is discharging, P B =min(P B_ref , P max -P PV ); Among them, P max Indicates the maximum power that the DC / AC unit can withstand.

[0015] Preferably, a first switch is provided between the power generation unit of the circuit architecture and the DC / DC unit, a second switch is provided between the DC / AC unit of the circuit architecture and the power grid, and a third switch is provided between the energy storage unit of the energy storage module and the Bi-DC / DC unit; if the energy storage module is not connected, the inverter architecture closes the first switch first and then the second switch when starting; if the energy storage module is connected, the inverter architecture closes the first switch first, then the third switch, and finally the second switch when starting.

[0016] Compared with the prior art, the beneficial effects of this application are: (1) The busbar of the circuit architecture allows external connection. Depending on whether the energy storage module is connected or not, the inverter architecture can be used as a power generation system or an energy storage power generation system, making the entire system structure very flexible.

[0017] (2) During the connection of the energy storage module, the control method of the circuit architecture of the power generation system, which is the basis of the inverter architecture, remains unchanged, thereby effectively reducing the control difficulty of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the architecture of an existing photovoltaic inverter system.

[0019] Figure 2 The figure is a schematic diagram of the architecture of an existing photovoltaic energy storage inverter system.

[0020] Figure 3 This is a schematic diagram of the overall structure of the architecture of this application.

[0021] Figure 4 A schematic diagram of the structure of an energy storage module connected to the architecture of this application.

[0022] Figure 5 This is a schematic diagram of the structure of the present application connecting two energy storage modules.

[0023] Figure 6 This is a schematic diagram of the control loop of each power unit after connecting the energy storage module for this application. DETAILED DESCRIPTION

[0024] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0025] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present application.

[0026] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0027] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] The terms "including" and "having" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0030] In order to better understand the technical solution of the present application, the structure of the existing photovoltaic system may be briefly described below.

[0031] like Figure 1 The figure shows a schematic diagram of the structure of an existing photovoltaic power generation system; its circuit architecture includes at least one PV unit, at least one DC / DC unit and at least one DC / AC unit. Taking the string photovoltaic power generation system as an example, there are N PV units and DC / DC units, N>1; the number of DC / AC units is one. Each PV unit is connected in series with the corresponding DC / DC unit and then connected in parallel with the DC bus; the DC side of the DC / AC unit is connected to the DC bus, and the AC side of the DC / AC unit is connected to the power grid.

[0032] like Figure 2 As shown, it is a structural schematic diagram of an existing photovoltaic power generation system; its circuit architecture is Figure 1 The circuit architecture corresponding to the photovoltaic power generation system shown also includes an energy storage module. The energy storage module includes batteries and Bi-DC / DC units connected in series, and the energy storage module is connected in parallel to the DC bus through the Bi-DC / DC unit; if there are multiple energy storage modules, then the multiple energy storage modules are connected in parallel.

[0033] It can be understood that for the above-mentioned photovoltaic power generation system, it only needs to consider the difference between the output power of the PV unit and the power required by the load when working. If the output power of the PV unit is greater than or equal to the power required by the load, the PV unit supplies power to the load; if the output power of the PV unit is less than the power required by the load, then the PV unit and the power grid are required to supply power to the load at the same time, or the power grid alone supplies power to the load. For the above-mentioned photovoltaic storage power generation system, it needs to consider the output power of the PV unit, the remaining power of the energy storage module and the power required by the load at the same time when working, and the charging and discharging control of the energy storage module is required based on different working scenarios. Therefore, there are certain differences in the structure and control process of the photovoltaic power generation system and the photovoltaic storage power generation system in the prior art, especially the control process; this leads to the inability of the photovoltaic power generation system and the photovoltaic storage power generation system in the prior art to directly match each other.

[0034] Based on the above analysis process, one aspect of the present application provides an inverter architecture that allows external bus connection, such as Figures 3 to 5 As shown, one preferred embodiment includes a communication module and a circuit architecture of a power generation system, the communication module is preset with a communication interface, and a bus interface is reserved at the DC bus position of the circuit architecture. The energy storage module can be connected to the communication interface and the bus interface respectively to access the inverter architecture; the communication module can control the charging and discharging of the energy storage module through the communication interface; the energy storage module can be charged and discharged through the bus interface.

[0035] It is understandable that when the inverter architecture of the present application is not connected to the energy storage module, it can be regarded as a power generation system under the control of the communication module, which can realize all the functions of the traditional power generation system. After the energy storage module is connected, through the connection of the energy storage module in the circuit architecture and the matching in the communication control, the inverter architecture can be transformed into an energy storage power generation system under the control of the communication module, which can realize all the functions of the traditional energy storage power generation system. That is, the busbar of the circuit architecture of this embodiment allows external connection, and depending on whether the energy storage module is connected or not, the inverter architecture can be used as a power generation system or an energy storage power generation system, making the entire system structure very flexible.

[0036] It should be known that the inverter architecture of the present application can be applied to photovoltaic power generation scenarios, as well as wind power generation and hydropower generation scenarios. For the convenience of subsequent description, the following content will be described in detail using the photovoltaic power generation scenario as an example.

[0037] In this embodiment, there are many specific implementations of the bus interface for connecting the energy storage module. For easy understanding, two specific examples are used for detailed description below.

[0038] Example 1: Figure 4As shown, the bus interface includes a positive bus interface Bus+ and a negative bus interface Bus- respectively connected to the positive and negative busbars. The energy storage module can be connected to the interface Bus+ and the interface Bus- respectively through the connection end of the Bi-DC / DC unit. When there are multiple energy storage modules connected, the multiple energy storage modules are connected in parallel.

[0039] Example 2: If Figure 5 As shown, the bus interface includes a positive bus interface Bus+ and a negative bus interface Bus- respectively connected to the positive and negative busbars, and a bus midpoint interface Bus0 connected to the midpoint of the busbar. When the number of connected energy storage modules is an even number, the energy storage modules are divided into two groups of equal number; the energy storage modules of one group are connected in parallel to the interface Bus+ and the interface Bus0 through the connection end of the Bi-DC / DC unit, and the energy storage modules of the other group are connected in parallel to the interface Bus0 and the interface Bus- through the connection end of the Bi-DC / DC unit. When the number of connected energy storage modules is an odd number, one of the energy storage modules is connected to the interface Bus+ and the interface Bus- respectively through the connection end, and the remaining energy storage modules are divided into two groups of equal number to be connected in parallel to the interface Bus+ and the interface Bus0, and the interface Bus0 and the interface Bus- respectively.

[0040] It should be known that both of the above examples can meet the requirements of this application; and when there is only one energy storage module connected, the above two examples are equivalent. For the above two examples, the bus interface can include interfaces Bus+ and Bus- respectively connected to the positive and negative bus, and interface Bus0 connected to the midpoint of the bus, so when implementing the above example 1, interface Bus0 can be idle.

[0041] It can be understood that the voltage between the interface Bus+ and Bus- is the bus voltage V dc , the voltage between the interface Bus+ and the interface Bus0 and the voltage between the interface Bus0 and the interface Bus- are both half bus voltage, that is, V dc / 2. Therefore, the energy storage modules connected to the interfaces Bus+ and Bus- need to have higher voltage resistance, so it is preferred to connect the energy storage modules to the half bus. However, in order to ensure that all the excess power output by the PV unit can be stably stored in the energy storage module, or in other words, the energy storage module needs to ensure the voltage balance between the positive and negative buses when supplying power to the load; the number of energy storage modules connected between the interface Bus+ and the interface Bus0 and the number of energy storage modules connected between the interface Bus0 and the interface Bus- need to be consistent.

[0042] Specifically, the specific connection method for the energy storage module is also related to the number of energy storage modules connected. Figure 4As shown, if there is only one energy storage module connected, then in order to ensure the stable charging and discharging of the energy storage module, the energy storage module must be connected to the positive and negative busbars of the circuit architecture. If there are two energy storage modules connected, in order to ensure the stable charging and discharging of the energy storage module, the two energy storage modules can be connected to the positive and negative busbars of the circuit architecture at the same time. Of course, in order to further reduce the withstand voltage requirements of the energy storage module; as Figure 5 As shown, the two energy storage modules can also be connected to the positive half bus and the negative half bus respectively. If the number of energy storage modules is greater than two, the above example 1 can be used to connect to the circuit architecture directly; of course, in order to further reduce the withstand voltage performance of the energy storage module, the above example 2 can be used to connect to the circuit architecture according to the parity of the number of energy storage modules.

[0043] In this embodiment, Figures 3 to 5 As shown, the communication module includes a communication bus, a processor and a first control unit. The processor and the first control unit are both connected to the communication bus; there are many types of commonly used processors. For ease of understanding, the processor in this embodiment is illustrated by taking ARM as an example. ARM can send instructions to the first control unit through the communication bus to control each power unit in the circuit architecture according to the user's instructions or built-in programs. When the energy storage module is connected, the energy storage module can be connected to the communication interface of the communication bus through the second control unit, so that ARM can send charging and discharging instructions to the power unit of the energy storage module through the communication bus according to the feedback data of the first control unit.

[0044] It should be known that the specific structures and working principles of the ARM, the communication bus and the first control unit are well-known technologies to those skilled in the art, so they will not be elaborated in detail here. In order to facilitate the user to control the inverter architecture, the communication module may also include a display unit, which may be connected to the ARM; the user may know the current state of the inverter architecture through the display unit, and may also input control instructions to the ARM through the display unit.

[0045] It can be understood that, from the foregoing content, the power unit of the circuit architecture includes a DC / DC unit and a DC / AC unit, so a single control chip can be used to control all DC / DC units and DC / AC units. However, considering that the control logic of different power units may be different, the number of interfaces of a single control chip may not meet the use requirements; therefore, different control chips can be used to control the DC / DC unit and the DC / AC unit respectively. That is, the first control unit includes a first control chip and a second control chip, which can be marked by DSP_DC / DC and DSP_DC / AC respectively. The control chip DSP_DC / DC can send instructions for control to the DC / DC unit and receive the power generation feedback from the DC / DC unit; the control chip DSP_DC / AC can send instructions for control to the DC / AC unit. Since the power unit of the energy storage module only has a Bi-DC / DC unit, the second control unit only needs to use a single control chip DSP_Bi-DC / DC to control the Bi-DC / DC unit.

[0046] It should be known that the control chip DSP_DC / DC can control all DC / DC units at the same time, and the control chip DSP_Bi-DC / DC can also control multiple Bi-DC / DC units at the same time. The specific structures and working principles of the control chip DSP_DC / DC, the control chip DSP_DC / AC and the control chip DSP_Bi-DC / DC are well-known technologies to those skilled in the art, so they will not be elaborated in detail here.

[0047] It should be known that the program for controlling the charge and discharge of the energy storage module can be stored in the ARM in advance; when the energy storage module is not connected to the circuit architecture and the communication architecture, the program is in an inactive state; and when the energy storage module is connected to the circuit architecture and the communication architecture, the program is activated. When the program is not activated, the control chip DSP_DC / DC only needs to control the DC / DC unit; after the program is activated, the control chip DSP_DC / DC controls the DC / DC unit while also receiving the output power information fed back by the DC / DC unit, so as to facilitate the subsequent control chip DSP_Bi-DC / DC to control the charge and discharge of the energy storage module. For ease of understanding, the specific control process of the inverter architecture will be described in detail below.

[0048] Another aspect of the present application provides a control method for the inverter architecture allowing busbar external connection, such as Figure 6As shown, one preferred embodiment includes the following steps: when the circuit architecture is not connected to the energy storage module, the DC / DC unit of the circuit architecture performs MPPT power control, and the DC / AC unit of the circuit architecture performs bus voltage maintenance control. When the circuit architecture is connected to the energy storage module, the control mode of the DC / DC unit and the DC / AC unit remains unchanged, and the Bi-DC / DC unit of the energy storage module performs charge and discharge control according to the scheduling requirements of the system and the output power limitation of the power generation unit in the circuit architecture.

[0049] It can be understood that when the energy storage module is not connected to the circuit architecture, the inverter architecture is used as a traditional power generation system; then in the power generation system, the bus voltage of the system is maintained by the DC / AC unit side, and the MPPT power of the system is controlled by the DC / DC unit. That is, the control chip DSP_DC / DC controls the DC / DC unit through MPPT tracking to control the MPPT power of the system, and the control chip DSP_DC / AC controls the DC / AC unit according to the bus voltage change to maintain the bus voltage of the system. After the energy storage module is connected to the circuit architecture, the circuit architecture of the power generation system in the inverter architecture still maintains the MPPT power control of the DC / DC unit and the bus voltage maintenance control of the DC / AC unit. At the same time, the control chip DSP_Bi-DC / DC controls the charging and discharging of the Bi-DC / DC unit of the energy storage module according to the scheduling requirements of the system. That is, in the entire control process of the inverter architecture, the control process of the circuit architecture has nothing to do with whether the energy storage module is connected or not. Before and after the energy storage module is connected, the control process of the circuit architecture does not need to be changed, which can effectively reduce the control difficulty of the entire inverter architecture when the energy storage module is connected.

[0050] In this embodiment, Figure 6 As shown, the control loop of the DC / DC unit includes a voltage outer loop and a current inner loop; the control of the DC / DC unit includes the following process: the voltage outer loop uses the comparison result of the MPPT tracking result with the output voltage of the power generation unit as the input of the current inner loop, and then the current inner loop generates a control signal for driving the DC / DC unit according to the comparison of the output of the voltage outer loop with the output current of the power generation unit.

[0051] Specifically, there are many control loop structures that can realize the above control process. For the sake of easy understanding, one of the control loop structures will be described in detail below. Figure 6 As shown, in the voltage outer loop, the output voltage command V of the power generation unit can be obtained according to the result of MPPT tracking. PV * , the voltage command V PV * And the output voltage V of the power generation unit collected PVThe comparison is performed by the comparator, and the comparison result is sent to the PI controller to obtain the output value I of the voltage outer loop. PV * The output value of the voltage outer loop is the input value of the current inner loop, which is also the output current I of the power generation unit. PV The command value is, then the output current I PV and command value I PV * The comparison is made by the comparator, and the comparison result is sent to the PI controller, which can output a duty cycle signal for driving and controlling the DC / DC unit.

[0052] In this embodiment, Figure 6 As shown, the control loop of the DC / AC unit includes a voltage outer loop and a current inner loop; the control of the DC / AC unit includes the following process: the voltage outer loop uses the comparison result between the bus voltage and the set command value as the input of the current inner loop, and at the same time uses the output current of the DC / AC unit and the output of the grid-side phase-locked loop as the input of the current inner loop, and then modulates the output of the current inner loop after passing through the current inner loop to obtain a control signal for controlling the DC / AC unit.

[0053] Specifically, there are many control loop structures that can realize the above control process. For the sake of easy understanding, one of the control loop structures will be described in detail below. Figure 6 As shown, in the voltage outer loop, the collected bus voltage V dc_sum With the set command value V dc_sum * The comparison is performed by the comparator, and the comparison result is sent to the PI controller to obtain the input value I of the current inner loop. d * , the input value of the current inner loop I d * That is, the command value of the d-axis component of the output current of the DC / AC unit on the AC side. In the current inner loop, the output current i of the DC / AC unit on the AC side can be collected. a 、i b and i c The grid current is converted into the corresponding d-axis component i by the phase angle information output by the phase-locked loop. d and the q-axis component i q The obtained d-axis component i d With the command value I d * After comparison by the comparator, it is sent to the PI controller, and the obtained q-axis component i q With the set command value I q *After comparison by the comparator, it is sent to the PI controller; finally, the current inner loop can convert the output results of the two PI controllers and the zero sequence into the coordinates of the abc axis, perform SPWM modulation on the converted results, and obtain the duty cycle signal for driving and controlling the DC / AC unit.

[0054] In this embodiment, Figure 6 As shown, the charging and discharging control of the Bi-DC / DC unit includes the following process: according to the system scheduling demand P B_ref The power generation unit P in the circuit architecture PV The charging and discharging power P of the energy storage module is calculated based on the limitation of B ; According to the obtained charge and discharge power P B Calculate the bus current command I corresponding to the current inner loop B * In the current inner loop, the calculated bus current command I B * And the working current I of the energy storage module B The comparison is performed by a comparator, and the comparison result is sent to a PI controller to obtain a duty cycle control signal for driving the Bi-DC / DC unit.

[0055] It should be known that in the inverter architecture, the reactive power bearing capacity of the DC / AC unit is relatively weak, so the traditional inverter architecture needs to be set up to prevent reverse flow, that is, the grid is not allowed to charge the battery of the energy storage module; this means that when the charging and discharging power P of the energy storage module is B When calculating the charging power of the energy storage module, it is necessary to ensure that the charging power of the energy storage module is less than the output power of the power generation unit. At the same time, in order to ensure the working safety of the DC / AC unit, when the energy storage module and the power generation unit are generating electricity at the same time, the sum of the power generation power of the energy storage module and the output power of the power generation unit should be less than the maximum power P that the DC / AC unit can withstand. max .

[0056] Based on the above analysis results, in order to ensure the safety of the inverter architecture during operation, after the energy storage module is connected to the circuit architecture, the DC side of the circuit architecture needs to increase the output power P of the power generation unit. PV The communication bus is transmitted to the control chip DSP_Bi-DC / DC corresponding to the energy storage module, so that the Bi-DC / DC unit can be dispatched according to the system's scheduling requirements P B_ref And the power generation P PV The limit of the energy storage module charging and discharging power P is obtained. B The specific calculation rules are: When the energy storage module needs to be charged, the power generation P PV and the system scheduling requirement P B_refThe smaller value of B , so that the charging power of the energy storage module can be guaranteed to be less than or equal to the output power of the power generation unit, and there will be no scenario where the power grid provides power to the energy storage module. The discharge direction of the energy storage module can be defined as positive, so when charging, the charging power P B Add a minus sign in front of , then the charging power P B The calculation method can be equivalent to: P B =-min(P B_ref , P PV ).

[0057] When the energy storage module needs to discharge, the maximum power P that the DC / AC unit can withstand can be max Subtract the output power P of the power generation unit PV The value of and the system scheduling requirement P B_ref The smaller value of B This ensures that the sum of the discharge power of the energy storage module and the output power of the power generation unit is less than or equal to the maximum power that the DC / AC unit can withstand. B The calculation method can be equivalent to: P B =min(P B_ref , P max -P PV ).

[0058] In this embodiment, Figure 3 and Figure 4 As shown, a first switch S is provided between the power generation unit and the DC / DC unit of the circuit architecture. PV A second switch S is provided between the DC / AC unit of the circuit architecture and the power grid. ac A third switch S is provided between the energy storage unit of the energy storage module and the Bi-DC / DC unit. B There are different plug-in and unplug start methods for the inverter architecture before and after the energy storage module is connected; if the energy storage module is not connected, the inverter architecture closes the first switch S when starting. PV , then close the second switch S ac ; If the energy storage module is connected, the inverter architecture will close the first switch S when starting. PV , then close the third switch S B , and finally close the second switch S ac .

[0059] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. An inverter architecture that allows external bus connection, characterized in that: include: A circuit architecture of a communication module and a power generation system, wherein the communication module is preset with a communication interface, and a bus interface is reserved at a DC bus position of the circuit architecture; The energy storage module is suitable for being connected to the communication interface and the bus interface respectively to access the inverter architecture; The communication module is suitable for controlling the charging and discharging of the energy storage module through the communication interface; the energy storage module is suitable for charging and discharging through the bus interface.

2. The inverter architecture allowing busbar external connection according to claim 1, characterized in that: The bus interface comprises a positive bus interface and a negative bus interface connected to the positive and negative busbars respectively; The energy storage module is suitable for being connected to the positive bus interface and the negative bus interface respectively through the connection ends, and a plurality of the energy storage modules are connected in parallel.

3. The inverter architecture allowing busbar external connection according to claim 1, characterized in that: The busbar interface includes a positive busbar interface and a negative busbar interface connected to the positive and negative busbars respectively, and a busbar midpoint interface connected to the busbar midpoint; When the number of the connected energy storage modules is an even number, the energy storage modules are divided into two groups of equal number; the energy storage modules in one group are connected in parallel to the positive bus interface and the bus midpoint interface through a connecting end, and the energy storage modules in the other group are connected in parallel to the bus midpoint interface and the negative bus interface through a connecting end; When the number of the connected energy storage modules is an odd number, one of the energy storage modules is connected to the positive bus interface and the negative bus interface through the connecting end, and the remaining energy storage modules are divided into two groups of equal number to be connected in parallel with the positive bus interface and the bus midpoint interface, and the bus midpoint interface and the negative bus interface, respectively.

4. The inverter architecture allowing busbar external connection according to any one of claims 1 to 3, characterized in that: The communication module includes a communication bus, a processor and a first control unit; The processor and the first control unit are both connected to the communication bus, so that the processor sends instructions for controlling each power unit in the circuit architecture to the first control unit through the communication bus; When connected, the energy storage module is connected to the communication interface through the second control unit, and the processor is suitable for sending charging and discharging instructions to the power unit of the energy storage module through the communication bus according to the feedback data of the first control unit.

5. The inverter architecture allowing external bus connection according to claim 4, characterized in that: The power unit of the circuit architecture includes a DC / DC unit and a DC / AC unit, and the first control unit includes a first control chip and a second control chip; The first control chip is adapted to issue control instructions to the DC / DC unit and receive the generated power fed back by the DC / DC unit; The second control chip is suitable for sending control instructions to the DC / AC unit.

6. A control method for an inverter architecture that allows external bus connection according to any one of claims 1 to 5, characterized in that: The steps include: When the circuit architecture is not connected to the energy storage module, the DC / DC unit of the circuit architecture performs MPPT power control, and the DC / AC unit of the circuit architecture performs maintenance control of the bus voltage; When the circuit architecture is connected to the energy storage module, the control methods of the DC / DC unit and the DC / AC unit remain unchanged, and the Bi-DC / DC unit of the energy storage module performs charging and discharging control according to the scheduling requirements of the system and the output power limitation of the power generation unit in the circuit architecture.

7. The control method of the inverter architecture allowing busbar external connection according to claim 6, characterized in that: The control loops of the DC / DC unit and the DC / AC unit each include a voltage outer loop and a current inner loop; The control of the DC / DC unit includes the following process: the voltage outer loop uses the comparison result of the MPPT tracking result with the output voltage of the power generation unit as the input of the current inner loop, and then the current inner loop generates a control signal for driving the DC / DC unit according to the comparison of the output of the voltage outer loop with the output current of the power generation unit; The control of the DC / AC unit includes the following process: the voltage outer loop uses the comparison result between the bus voltage and the set command value as the input of the current inner loop, and at the same time uses the output current of the DC / AC unit and the output of the grid-side phase-locked loop as the input of the current inner loop, and then modulates the output of the current inner loop after passing through the current inner loop to obtain a control signal for controlling the DC / AC unit.

8. The control method of the inverter architecture allowing external bus connection according to claim 6, characterized in that: The charge and discharge control of the Bi-DC / DC unit includes the following process: According to the system scheduling requirements P B_ref and the power generation power P of the power generation unit in the circuit architecture PV The charging and discharging power P of the energy storage module is calculated based on the limitation of B ; According to the obtained charge and discharge power P B Calculate the bus current command I required by the current inner loop B * , and then in the current inner loop through the bus current command I B * and the operating current I of the energy storage module B A control signal for driving the Bi-DC / DC unit is obtained.

9. The control method of the inverter architecture allowing busbar external connection according to claim 8, characterized in that: The discharge direction of the energy storage module is defined as positive, and the charge and discharge power P of the energy storage module is defined as positive. B The calculation formula is as follows: When the energy storage module is charging, P B =-min(P B_ref , P PV ); When the energy storage module is discharging, P B =min(P B_ref , P max -P PV ); Among them, P max Indicates the maximum power that the DC / AC unit can withstand.

10. The control method of the inverter architecture allowing busbar external connection according to claim 6, characterized in that: A first switch is provided between the power generation unit of the circuit architecture and the DC / DC unit, a second switch is provided between the DC / AC unit of the circuit architecture and the power grid, and a third switch is provided between the energy storage unit of the energy storage module and the Bi-DC / DC unit; If the energy storage module is not connected, the inverter architecture closes the first switch first and then the second switch when starting; If the energy storage module is connected, the inverter architecture first closes the first switch, then the third switch, and finally the second switch when starting.

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