Multi-port photovoltaic storage complementary power supply system and control method and control system thereof

Abstract

The present invention provides a multi-port photovoltaic-storage complementary power supply system, which is constructed based on a one-to-many dual-active bridge-type micro-inverter structure, including multiple DC ports, one AC port, multiple DC conversion branches, one AC conversion branch and a multi-winding high-frequency transformer. The DC port can be connected to a DC load, a photovoltaic module or a battery, and the AC port can be connected to a power grid or an AC load. This architecture applies micro-inverters to the application scenario of photovoltaic-storage complementary mobile power supplies, so that the one-to-many micro-inverters have high practical value. The present invention also provides a control method and control system for a multi-port photovoltaic-storage complementary power supply system, which divides the working states of the photovoltaic-storage complementary power supply into grid-connected, independent load and standby working conditions according to the flow of power, and changes the corresponding control strategy according to different working conditions, so that the photovoltaic-storage complementary power supply can still ensure stable operation when facing more complex actual working conditions, thereby improving the reliability of the photovoltaic-storage complementary power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-port photovoltaic-storage complementary power supply control, and in particular to a multi-port photovoltaic-storage complementary power supply system and a control method and control system thereof. Background Art

[0002] The photovoltaic-storage complementary power supply is a portable charger that can be carried around, store electricity, and output AC and DC. It is especially used in situations where there is no external power supply. Its main components include: batteries for energy storage, circuits for stabilizing output voltage, and charger circuits for charging built-in batteries. Multi-port DC-AC converters have the characteristics of bidirectional power transmission, so they can be combined with energy storage to serve as photovoltaic-storage complementary mobile power converters.

[0003] There are many application scenarios for using multi-port DC-AC converters as photovoltaic and energy storage complementary mobile power converters. According to the power flow direction, they can be divided into three categories of application scenarios, namely grid-connected, independent load and standby conditions. However, in each application scenario, corresponding control strategies need to be designed for each condition. However, there are currently no relevant research results, which has become a problem that needs to be urgently solved in this field.

[0004] At present, no description or report of similar technology to the present invention has been found, and similar information at home and abroad has not been collected yet. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a multi-port photovoltaic-storage complementary power supply system and a control method and control system thereof.

[0006] According to one aspect of the present invention, a multi-port photovoltaic-storage complementary power supply system is provided, which is constructed based on a one-to-many dual-active bridge micro-inverter structure, including: multiple DC ports, one AC port, multiple DC conversion branches, one AC conversion branch and a multi-winding high-frequency transformer; wherein:

[0007] Each of the DC conversion branches adopts a full-bridge conversion circuit or a half-bridge conversion circuit;

[0008] The AC conversion branch includes two bidirectional switch tubes and two non-polarized capacitors, the two bidirectional switch tubes are connected in series and then connected in parallel with the two series-connected non-polarized capacitors;

[0009] The primary side of the multi-winding high-frequency transformer is connected to each of the DC conversion branches respectively, and the secondary side of the multi-winding high-frequency transformer is connected to the AC conversion branch;

[0010] The input end of each of the DC conversion branches is respectively connected to a DC port;

[0011] The output end of the AC conversion branch is connected to the AC port.

[0012] Preferably, each of the DC ports is used to connect a DC load, a photovoltaic module or a battery, and the AC port is used to connect a power grid or an AC load; according to the connection status and power flow direction of the DC port and the AC port, the working state of the photovoltaic storage complementary power supply of the system is divided into three application scenarios: standby, grid-connected and independent load; wherein:

[0013] In the standby scenario, multiple DC ports are connected to PV panels and batteries respectively, the AC port does not work, and power flows from the PV DC port to the battery DC port;

[0014] In the grid-connected scenario, it includes any of the following working states:

[0015] - Multiple DC ports are connected to PV panels and batteries respectively, and the AC ports are connected to the grid. The DC ports of the batteries are in a charging state, and power is provided by the DC ports and AC ports of the PV panels.

[0016] - Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The DC port of the PV is not working, and the DC port of the battery is in a charging state. Power flows from the AC port to the DC port of the battery.

[0017] In the independent load scenario, the working status includes any of the following:

[0018] - Multiple DC ports are connected to the photovoltaic modules and batteries respectively, and the AC ports are connected to the loads, and power flows from the multiple DC ports to the AC ports;

[0019] -Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads, so that power flows from the DC ports of PV panels to the DC ports and AC ports of batteries;

[0020] - Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC port of the battery is not working, and the DC port of the PV is in a power generation state. Power flows from the DC port of the PV to the AC port.

[0021] -Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC port of the PV is not working, and the DC port of the battery is in a discharging state. Power flows from the DC port of the battery to the AC port.

[0022] According to another aspect of the present invention, a control method for the above-mentioned multi-port photovoltaic-storage complementary power supply system is provided. According to the situation that the AC port is connected to the power grid or the AC load, a control strategy on the battery side is constructed to control the transmission power of the multi-port photovoltaic-storage complementary power supply system.

[0023] Preferably, when the AC port is connected to the grid, the corresponding control strategy includes:

[0024] Generate the grid-connected current given value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , get N+M grid-connected current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) ; Where N is the number of photovoltaic modules and M is the number of batteries;

[0025] Obtain the grid voltage phase angle θ, and combine the grid voltage phase angle θ and the power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0026] Generate external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0027] Generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0028] By utilizing the obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system and the switching logic of each switch tube of the multi-port photovoltaic-storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system is controlled.

[0029] Preferably, the control method further includes any one or more of the following:

[0030] - The grid-connected current given value amplitude I of the dual active bridge type micro-inverter connected to the battery by generating M paths m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ,include:

[0031] Get the battery terminal voltage v bati(i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M), with the battery terminal voltage v bati (i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M) as input, and calculate the grid-connected current given value amplitude I of the dual active bridge micro-inverter connected to the battery with M paths. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ;

[0032] in:

[0033] The battery output current given value I bat,refi (i=0,1,…,M) is obtained based on the battery state of charge, which is negative when the battery is charging and positive when the battery is discharging;

[0034] - generating an external phase angle compensation value ΔD 21b methods, including:

[0035] A master-slave control method is used to perform closed-loop control on the grid-connected current; wherein the master-slave control method includes: in the multi-port photovoltaic storage complementary power supply system, only one micro-inverter is used as the master to perform current closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master compensates for the distortion of the total grid-connected current;

[0036] In the grid-connected condition, the N+1th micro-inverter on the battery side is working, and the N+1th micro-inverter is selected as the host. The sum of the instantaneous current given values ​​i g,ref The external phase angle compensation value ΔD is generated by subtracting the actual grid-connected current 21b .

[0037] Preferably, when the AC port is connected to an independent load, the corresponding control strategy includes:

[0038] Generate the grid-connected current given value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , combined with the grid voltage phase angle reference value θ ref , by I g，refi =I m.refi sinθ ref (i=1,2,…,N+M) to obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0039] Generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the calculated internal and external phase shift angles;

[0040] By judging the AC side voltage and calculating the gain compensation, the input required for closed-loop control is obtained, and the external phase angle compensation value ΔD is generated under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0041] Feedforward calculation is performed according to the no-load startup condition on the AC side, which is used for AC side power control to avoid overvoltage on the AC side; according to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic and energy storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic and energy storage complementary power supply system is controlled.

[0042] Preferably, the control method further includes any one or more of the following:

[0043] -Use the grid-connected current given value amplitude of the dual active bridge microinverter connected to the photovoltaic module on N paths and the AC side load resistance calculated in real time to determine the grid-connected current given value amplitude I of the dual active bridge microinverter connected to the battery on M paths m,refi (i=N+1,N+2,…,N+M) is:

[0044]

[0045] Where: P bat，ref is the battery reference power, P g，ref is the AC side reference power, P pv，ref1 ~P pv，refN is the reference power of N micro-inverters connected to the photovoltaic modules, v d，ref is the AC measurement reference voltage, R L is the equivalent load resistance, I m，ref1 ~I m，refN is the grid-connected current given value amplitude of the dual active bridge microinverter connected to N photovoltaic modules, and M is the number of batteries;

[0046] Among them, the resistance value of the load resistor on the AC side is calculated in real time according to the sampled voltage and sampled current on the AC side;

[0047] -Get the given value of the AC voltage v g,ref And the AC side voltage sampling value v g , generate the external phase angle compensation value ΔD21b .

[0048] According to the third aspect of the present invention, a control system for the above-mentioned multi-port photovoltaic-storage complementary power supply system is provided. According to the situation that the AC port is connected to the power grid or the AC load, a control module on the battery side is constructed to control the transmission power of the multi-port photovoltaic-storage complementary power supply system.

[0049] Preferably, when the AC port is connected to the grid, the corresponding control module includes: an MPPT module, a phase-locked loop module, a battery power setpoint generation module, a feedforward controller, a current loop and a phase shift controller; wherein:

[0050] The MPPT module is used to generate a grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the dual active bridge type micro-inverter connected to the battery M-way m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) The grid-connected current given value amplitudes output by the two modules are combined to obtain N+M grid-connected current given value amplitudes I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) ;

[0051] The phase-locked loop module is used to obtain the grid voltage phase angle θ, and combines the grid voltage phase angle θ and the power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) and respectively calculating the internal and external phase shift angles of the multi-port photovoltaic storage complementary power supply system through a plurality of the feedforward controllers;

[0052] The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0053] The current loop is used to generate an external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0054] The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0055] The obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system are used to control the grid-connected current to reach a given value, and control the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system.

[0056] Preferably, when the AC port is connected to an independent load, the corresponding control module includes: an MPPT module, a battery power set value generation module, a feedforward controller, a feedforward calculation module, a current loop module, a phase shift controller module and a voltage loop module; wherein:

[0057] The MPPT module is used to generate a grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the M-way dual active bridge type micro-inverter connected to the battery according to the grid-connected current given value amplitude of the N-way dual active bridge type micro-inverter connected to the photovoltaic module. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ;

[0058] The feedforward controller is used to set the grid-connected current set value amplitude I of the N dual active bridge micro-inverters connected to the photovoltaic components. m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) Combined with the grid voltage phase angle reference value θ ref , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0059] The phase shift controller module generates the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the calculated internal and external phase shift angles;

[0060] The current loop module obtains the input required for closed-loop control through AC side voltage judgment and gain compensation calculation, which is used to implement closed-loop control;

[0061] The voltage loop module is used to generate an external phase angle compensation value ΔD under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0062] The feedforward calculation module is used to perform feedforward calculation according to the no-load startup condition of the AC side, so as to avoid overvoltage on the AC side;

[0063] According to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic and energy storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic and energy storage complementary power supply system is controlled.

[0064] Due to the adoption of the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0065] The multi-port photovoltaic-storage complementary power supply system provided by the present invention applies the micro-inverter to the application scenario of photovoltaic-storage complementary mobile power supply, so that the one-to-many micro-inverters have higher practical value.

[0066] The control method and control system of the multi-port photovoltaic-storage complementary power supply system provided by the present invention divide the working conditions into grid-connected, independent load and standby according to the power flow direction, and design corresponding control strategies for each working condition, so that the photovoltaic-storage complementary power supply can handle more complex actual working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0068] Figure 1 It is a schematic diagram of the composition structure of a photovoltaic-storage complementary mobile power system based on one-to-many dual-active bridge micro-inverters in a preferred embodiment of the present invention;

[0069] Figure 2 This is an overall control block diagram of a photovoltaic-storage complementary power supply system under grid-connected conditions in a preferred embodiment of the present invention;

[0070] Figure 3 This is an overall control block diagram of a photovoltaic-storage complementary power supply system under independent load conditions in a preferred embodiment of the present invention;

[0071] Figure 4 This is a flow chart of real-time load calculation of a photovoltaic-storage complementary power supply system under independent load conditions in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0072] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several variations and improvements can also be made, which all belong to the protection scope of the present invention. For the parts not described below, reference can be made to the description or prior art in the summary of the invention.

[0073] An embodiment of the present invention provides a multi-port photovoltaic-storage complementary power supply system, which is implemented based on a one-to-many dual-active bridge micro-inverter structure.

[0074] In this embodiment, the multi-port photovoltaic-storage complementary power supply system may include: multiple DC ports, one AC port, multiple DC conversion branches, one AC conversion branch and a multi-winding high-frequency transformer; wherein:

[0075] Each DC conversion branch is a full-bridge conversion circuit or a half-bridge conversion circuit;

[0076] The AC conversion branch may include two bidirectional switch tubes and two non-polarized capacitors, wherein the two bidirectional switch tubes are connected in series and then connected in parallel with the two series-connected non-polarized capacitors;

[0077] The primary side of the multi-winding high-frequency transformer is connected to each DC conversion branch, and the secondary side of the multi-winding high-frequency transformer is connected to the AC conversion branch. In a specific application example, the parameters of the multi-winding high-frequency transformer can be the transformer turns ratio n1:n2:…:n (N+M) , the primary leakage inductance of the multi-winding high-frequency transformer can be L k1 , L k2 ,…,L k(N+M) And the primary excitation inductance of the multi-winding high-frequency transformer can be L m1 , L m2 …、L m(N+M) , where the excitation inductance is large enough, so it will not participate in the resonance process; N is the number of photovoltaic modules, and M is the number of batteries;

[0078] The input end of each DC conversion branch is respectively connected to a DC port;

[0079] The output end of the AC conversion branch is connected to the AC port.

[0080] Specifically, the DC port can be connected to a DC load, a photovoltaic module or a battery, and the AC port can be connected to a power grid or an AC load. According to the connection status of the AC and DC ports and the power flow direction, the working state of the photovoltaic-storage complementary power supply can be divided into three application scenarios: standby, grid-connected and independent load.

[0081] in:

[0082] The standby scenarios include the following specific conditions:

[0083] In the standby scenario, multiple DC ports are connected to PV panels and batteries respectively, the AC port does not work, and power flows from the PV DC port to the battery DC port.

[0084] The grid-connected scenarios include the following specific conditions:

[0085] Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The battery port is in a charging state, and power is provided by the PV DC port and the AC port.

[0086] The AC port is connected to the grid, the PV DC port is not working, the battery DC port is in charging state, and power flows from the AC port to the battery DC port.

[0087] Independent load scenarios include the following specific conditions:

[0088] The multiple DC ports are respectively connected to the photovoltaic modules and the batteries, and the AC ports are connected to the loads, and the power flows from the multiple DC ports to the AC ports;

[0089] Multiple DC ports are connected to photovoltaic modules and batteries respectively, and AC ports are connected to loads, and power flows from the photovoltaic DC ports to the battery DC ports and AC ports;

[0090] The battery DC port is not working, the PV DC port is in power generation state, the AC port is connected to the load, and power flows from the PV DC port to the AC port;

[0091] The PV DC port is not working, the battery DC port is in a discharging state, and power flows from the battery DC port to the AC port.

[0092] One embodiment of the present invention also provides a control method for the multi-port photovoltaic-storage complementary power supply system in the above embodiment. The method can construct a battery-side control strategy according to the situation of the AC port being connected to the power grid or the AC load, and control the transmission power of the multi-port photovoltaic-storage complementary power supply system.

[0093] In a preferred embodiment, when the AC port is connected to the grid, the corresponding control strategy includes:

[0094] Generate the grid-connected current given value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , get N+M grid-connected current given value amplitude I m,ref1 ,Im,ref2 ,…,I m,ref(N+M) ; Where N is the number of photovoltaic modules and M is the number of batteries;

[0095] Get the grid voltage phase angle θ, combined with the grid voltage phase angle θ and power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0096] Generate external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0097] Generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0098] By utilizing the obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system and the switching logic of each switch tube of the multi-port photovoltaic-storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system is controlled.

[0099] In a preferred embodiment, a grid-connected current set value amplitude I of M dual active bridge micro-inverters connected to the battery is generated. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , which may include:

[0100] Get the battery terminal voltage v bati (i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M), with the battery terminal voltage v bati (i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M) as input, and calculate the grid-connected current given value amplitude I of the dual active bridge micro-inverter connected to the battery with M paths. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ;

[0101] in:

[0102] Battery output current given value I bat,refi(i=0,1,…,M) is obtained based on the battery state of charge, which is negative when the battery is charging and positive when the battery is discharging.

[0103] In a preferred embodiment, the external phase angle compensation value ΔD is generated 21b The methods may include:

[0104] The master-slave control method is used to perform closed-loop control on the grid-connected current; the master-slave control method includes: in the multi-port photovoltaic storage complementary power supply system, only one micro-inverter is used as the master to perform current closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master compensates for the distortion of the total grid-connected current;

[0105] In the grid-connected condition, the N+1th micro-inverter on the battery side is working, and the N+1th micro-inverter is selected as the host. The sum of the instantaneous current given values ​​i g,ref The external phase angle compensation value ΔD is generated by subtracting the actual grid-connected current 21b .

[0106] Specifically, the control strategy provided in this preferred embodiment can be implemented by the following functional modules:

[0107] like Figure 2 As shown, when the AC port is connected to the grid, the functional modules corresponding to the control strategy may include: MPPT module, phase-locked loop module, battery power set value generation module, feedforward calculation module (which may include the first micro-inverter feedforward controller and the second micro-inverter feedforward controller), current loop and phase shift controller. The MPPT module generates the grid-connected current set value amplitude I of the N micro-inverters connected to the photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module generates the grid-connected current given value amplitude I of the M micro-inverters connected to the battery. m,ref1 ,I m,ref2 ,…,I m,refM ; In the battery power given value module, v bat is the battery terminal voltage; I bat,ref is the given value of the battery output current, which can be obtained based on the battery charge state. It is negative when the battery is charging and positive when the battery is discharging. The grid voltage phase angle θ can be obtained through the phase-locked loop, and combined with θ and the power factor angle I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) The instantaneous current given value I of multiple micro-inverters can be obtained g,ref1 ,I g,ref2 ,…,I g,ref(N+M), and calculate the internal and external phase shift angles of multiple micro-inverters respectively through multiple feedforward controllers. The grid-connected current closed-loop control adopts the master-slave control mode, that is, only one micro-inverter is used as the master to perform current closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master compensates for the distortion of the total grid-connected current. Since the N+1th micro-inverter on the battery side is working in all grid-connected conditions, the second micro-inverter is selected as the master, and the total grid-connected current given value i g,ref After subtracting the actual grid-connected current, the current controller generates the external phase angle compensation value ΔD 21b , and the calculated value of the external shift phase angle D 21b,cal After adding, the final external shift phase angle D is generated 21b .

[0108] In a preferred embodiment, when the AC port is connected to an independent load, the corresponding control strategy includes:

[0109] Generate the grid-connected current given value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , combined with the grid voltage phase angle reference value θ ref , by I g，refi =I m.refi sinθ ref (i=1,2,…,N+M) to obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0110] The switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system is generated according to the calculated internal and external phase shift angles;

[0111] By judging the AC side voltage and calculating the gain compensation, the input required for closed-loop control is obtained, and the external phase angle compensation value ΔD is generated under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0112] Feedforward calculation is performed according to the no-load startup condition on the AC side, which is used for AC side power control to avoid overvoltage on the AC side. According to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic-storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system is controlled.

[0113] In a preferred embodiment, the grid-connected current given value amplitude of the dual active bridge type micro-inverter connected to the photovoltaic module and the AC side load resistance calculated in real time are used to determine the grid-connected current given value amplitude I of the dual active bridge type micro-inverter connected to the battery. m,refi (i=N+1,N+2,…,N+M) can be:

[0114]

[0115] Where: P bat，ref is the battery reference power, P g，ref is the AC side reference power, P pv，ref1 ~P pv，refN is the reference power of N micro-inverters connected to the photovoltaic modules, v d，ref is the AC measurement reference voltage, R L is the equivalent load resistance, I m，ref1 ~I m，refN is the grid-connected current given value amplitude of the dual active bridge microinverter connected to N photovoltaic modules, and M is the number of batteries;

[0116] The resistance value of the load resistor on the AC side is calculated in real time according to the sampled voltage and current on the AC side.

[0117] In a preferred embodiment, the AC side voltage given value v is obtained. g,ref And the AC side voltage sampling value v g , generate the external phase angle compensation value ΔD 21b .

[0118] Specifically, the control strategy provided in this preferred embodiment can be implemented by the following functional modules:

[0119] like Figure 3 As shown in FIG. 1 , when the AC port is connected to an independent load, the functional modules corresponding to the control strategy may include: an MPPT module, a battery power set value generation module, a feedforward calculation module (which may include a first micro-inverter feedforward calculation module and a second micro-inverter feedforward calculation module), a phase shift controller module, a voltage loop module, a current loop module, and the like. The MPPT module and the battery power set value module respectively generate the grid-connected current set value amplitude I of the multiple micro-inverters. m,ref1 ,I m,ref2 ,…,Im,ref(N+M) ; Combined with the grid voltage phase angle reference value θ ref The instantaneous current given value I of the multi-channel micro-inverter can be obtained g,ref1 ,I g,ref2 ,…,I g,ref(N+M) The input of the voltage loop module is the AC side voltage given value v g,ref And the AC side voltage sampling value v g The voltage controller part of the current loop module includes the control logic switching and gain compensation parts. The battery power set value generation module needs to determine the AC side current amplitude set value I of the M micro-inverters connected to the battery according to the AC side current amplitude set value of the N micro-inverters output by the MPPT module and the load resistance value calculated in real time. m,refi (i=N+1,N+2,…,N+M), the calculation expression is:

[0120]

[0121] Where: P bat，ref is the battery reference power, P g，ref is the AC side reference power, P pv，ref1 ~P pv，refN is the reference power of N micro-inverters connected to the photovoltaic modules, v d，ref is the AC measurement reference voltage, R L is the equivalent load resistance, I m，ref1 ~I m，refN is the reference current of the N micro-inverters connected to the photovoltaic modules, and M is the number of batteries.

[0122] Specifically, the control method under independent load conditions needs to calculate the load resistance of the AC side in real time, and the method is to calculate the load resistance according to the AC side sampled voltage and sampled current. At the same time, the AC side needs to start with no load, and the method is to perform feedforward calculation according to the no-load start situation to avoid overvoltage on the AC side.

[0123] One embodiment of the present invention provides a control system for the multi-port photovoltaic-storage complementary power supply system in the above-mentioned embodiment. The system can construct a battery-side control module according to the situation of the AC port being connected to the power grid or the AC load, and control the transmission power of the multi-port photovoltaic-storage complementary power supply system.

[0124] In a preferred embodiment, when the AC port is connected to the grid, the corresponding control module includes: an MPPT module, a phase-locked loop module, a battery power setpoint generation module, a feedforward controller, a current loop and a phase shift controller; wherein:

[0125] The MPPT module is used to generate the grid-connected current set value amplitude I of N dual active bridge microinverters connected to photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the dual active bridge micro-inverter connected to the battery in M ​​circuits. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) The grid-connected current given value amplitudes output by the two modules are combined to obtain N+M grid-connected current given value amplitudes I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) ;

[0126] The phase-locked loop module is used to obtain the grid voltage phase angle θ, combined with the grid voltage phase angle θ and the power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) and calculate the internal and external phase shift angles of the multi-port photovoltaic-storage complementary power supply system respectively through multiple feedforward controllers;

[0127] The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0128] The current loop is used to generate the external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0129] The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles;

[0130] The obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system are used to control the grid-connected current to reach a given value, and to control the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system.

[0131] In a preferred embodiment, when the AC port is connected to an independent load, the corresponding control module includes: an MPPT module, a battery power set value generation module, a feedforward controller, a feedforward calculation module, a current loop module, a phase shift controller module and a voltage loop module; wherein:

[0132] The MPPT module is used to generate the grid-connected current set value amplitude I of N dual active bridge microinverters connected to photovoltaic modules.m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the M-way dual-active bridge type micro-inverter connected to the battery according to the grid-connected current given value amplitude of the N-way dual-active bridge type micro-inverter connected to the photovoltaic module. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ;

[0133] The feedforward controller is used to set the grid-connected current set value amplitude I of the dual active bridge microinverter connected to N photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) Combined with the grid voltage phase angle reference value θ ref , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively;

[0134] The phase shift controller module generates the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the calculated internal and external phase shift angles;

[0135] The current loop module obtains the input required for closed-loop control through AC side voltage judgment and gain compensation calculation, which is used to implement closed-loop control;

[0136] The voltage loop module is used to generate the external phase angle compensation value ΔD under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle;

[0137] The feedforward calculation module is used to perform feedforward calculation according to the no-load startup condition on the AC side to avoid overvoltage on the AC side;

[0138] According to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic and energy storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic and energy storage complementary power supply system is controlled.

[0139] The technical solution provided by the above embodiment of the present invention is further described below in conjunction with the accompanying drawings and a specific application example.

[0140] Figure 1This is a schematic diagram of a photovoltaic-storage complementary mobile power supply based on a one-to-many dual active bridge micro-inverter. Figure 1 As shown,

[0141] The photovoltaic storage complementary mobile power supply circuit based on one-to-many dual active bridge micro-inverter consists of photovoltaic module components, battery packs, DC bus capacitors, full-bridge circuits, multi-winding transformers, half-bridge circuits, and grid-side low-pass filters. The multiple primary DC side interfaces are connected to N photovoltaic modules and M battery packs respectively, and the N full-bridge circuits connected to the photovoltaic modules are composed of low-voltage switch tubes S 11 ~S 41 , S 12 ~S 42 , …, S 1N ~S 4N The DC port and electrolytic capacitor C bus1 The M-way full-bridge circuit connected to the battery pack consists of a low-voltage switch tube T 11 ~T 41 , T 12 ~T 42 ,…,T 1M ~T 4M The DC port and electrolytic capacitor C bus2 The grid side is a half-bridge circuit including switch tubes Q1~Q4 and film capacitors C1 / C2; due to the difference between the battery pack port voltage and the maximum power point voltage of the photovoltaic module, in order to achieve matching of the primary and secondary voltages, the transformer turns ratio n1:n2:…:n (N+M) In addition, the primary leakage inductance L of the multi-channel transformer can be adjusted. k1 , L k2 ,…,L k(N+M) The size of L is used to adjust the maximum transmission power of the two micro-inverters; the leakage inductance of each port of the transformer is L k1 , L k2 ,…,L k(N+M) , the excitation inductance of the two low-voltage side windings of the transformer are L m1 , L m2 …、L m(N+M) ; After the photovoltaic module is connected in parallel with the DC side bus capacitor, it is connected to the DC port of the input end of the low-voltage side full-bridge circuit, the AC side output end of the low-voltage side full-bridge is connected to the low-voltage side of the multi-winding transformer, the high-voltage side of the multi-winding transformer is connected to the AC port of the high-voltage side half-bridge circuit, the DC port of the high-voltage side half-bridge circuit is connected to the grid-side low-pass filter, and the grid-side low-pass filter is directly connected to the AC power grid; taking the first full-bridge circuit connected to the photovoltaic module as an example, the switch tube S in the full-bridge circuit 11 The source and switch tube S 21The drain of the three-winding transformer is connected to the positive electrode of a low-voltage port, and the switch tube S 31 The source and switch tube S 41 The drain of the three-winding transformer is connected to the negative pole of a low-voltage port, and the switch tube S 11 The drain and switch S 31 The drain of the switch tube S is connected to the positive electrode of the DC bus capacitor. 21 The source and switch tube S 41 The source of the switch Q1 is connected to the negative electrode of the DC bus capacitor; the connection method of the full-bridge circuit connected to the battery pack is the same as that of the full-bridge circuit on the photovoltaic module side, which will not be repeated; in the grid-side half-bridge circuit, the drain of the switch tube Q1 is connected to the positive electrode of the film capacitor C1, the source of the switch tube Q1 is connected to the source of the switch tube Q2, the drain of the switch tube Q2 is connected to the drain of the switch tube Q3, and is connected to the positive electrode of the high-voltage side port of the transformer, the source of the switch tube Q3 is connected to the source of the switch tube Q4, the drain of the switch tube Q4 is connected to the negative electrode of the film capacitor C2, the negative electrode of the film capacitor C1 is connected to the positive electrode of the film capacitor C2, and is connected to the negative electrode of the high-voltage side port of the transformer; for the micro-inverter connected to the photovoltaic module, the DC side capacitor C bus1 It can absorb most of the double frequency pulsating power to reduce the fluctuation of the terminal voltage of the photovoltaic module and achieve a higher MPPT efficiency; however, for the micro-inverter connected to the battery, since the battery itself has a very small impedance, the impedance at the double frequency of 100Hz is much smaller than that of C bus2 The impedance of the branch circuit cannot absorb the double frequency pulsation. bus2 The capacitance value can be configured to be smaller, which plays the role of voltage support and absorbing part of the sub-high frequency current of the switch. Figure 1 In the photovoltaic-storage complementary mobile power supply based on one-to-many dual active bridge micro-inverters shown, the control method in the above embodiment of the present invention can be used.

[0142] Figure 2 This is the overall control block diagram of the photovoltaic and energy storage complementary power supply under grid-connected conditions. Figure 3 This is an overall control block diagram of a photovoltaic-storage complementary power supply under independent load conditions, which has been specifically described in the control method provided in this embodiment and will not be repeated here.

[0143] Figure 4This is a flowchart of real-time load calculation of the photovoltaic-storage complementary power supply under independent load conditions. Under independent load conditions, since the resistance of the AC side load is not known in advance, the transmission power of the microinverter is an unknown quantity. Feedforward control needs to calculate the power transfer ratio based on the given value of the transmission power to calculate the internal and external phase shift angles, which brings difficulties to the application of feedforward control. On the other hand, since the transmission power of the microinverter is very sensitive to the external phase shift angle, if the feedforward control is removed and only voltage closed-loop control is used, the regulation effect is poor. Therefore, it is necessary to calculate the load resistance in real time to obtain the given value of the AC side power. Figure 4 As shown, the basic idea of ​​real-time calculation of load resistance is to calculate the load resistance based on the AC side sampling voltage and sampling current, and use the calculated load resistance value for feedforward calculation. However, since the AC side voltage is not established when starting the machine, the real-time calculation of the load resistance cannot be performed. At this time, it is necessary to perform feedforward calculation according to the no-load start-up situation, so that the machine is under heavy load conditions when starting to avoid overvoltage on the AC side. Specifically: If the machine is not started, the no-load start designation is executed. Before the real-time calculation of the AC side load, it is assumed that the load current starts to rise slowly from 0, so the AC side power set value also starts to rise slowly from 0. The calculated AC side power set value is feedforward calculated, and after the AC side voltage is established, it is converted into the real-time sampled AC side voltage v ac and current i ac Perform feedforward calculation; if the machine has started, directly sample the AC side voltage v ac and current i ac , calculate the AC side load R according to the current and voltage values L , combined with the AC side reference voltage v d,ref Calculate the AC side power setpoint to participate in the feedforward control calculation.

[0144] Of course, the specific circuits in the above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. In other embodiments, other circuit forms may be used to achieve the same function.

[0145] The multi-port photovoltaic-storage complementary power supply system and control method provided by the above-mentioned embodiment of the present invention can be applied to the photovoltaic-storage complementary mobile power supply scenario based on the characteristic that power can flow in both directions of the one-to-many dual-active bridge type micro-inverter, and can be divided into grid-connected, independent load and standby working conditions according to the power flow direction. Corresponding control strategies are designed for each working condition, so that the one-to-many dual-active bridge type micro-inverter has a higher practical value.

[0146] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A control method for a multi-port photovoltaic-storage complementary power supply system, characterized in that: The multi-port photovoltaic-storage complementary power supply system is constructed based on a one-to-many dual-active bridge micro-inverter structure, including: multiple DC ports, one AC port, multiple DC conversion branches, one AC conversion branch and a multi-winding high-frequency transformer; wherein: Each of the DC conversion branches adopts a full-bridge conversion circuit or a half-bridge conversion circuit; The AC conversion branch includes two bidirectional switch tubes and two non-polar capacitors, the two bidirectional switch tubes are connected in series and then connected in parallel with the two series-connected non-polar capacitors; The primary side of the multi-winding high-frequency transformer is connected to each of the DC conversion branches respectively, and the secondary side of the multi-winding high-frequency transformer is connected to the AC conversion branch; The input end of each of the DC conversion branches is respectively connected to a DC port; The output end of the AC conversion branch is connected to the AC port; Each of the DC ports is used to connect a DC load, a photovoltaic module or a battery, and the AC port is used to connect a power grid or an AC load; according to the connection status and power flow direction of the DC port and the AC port, the working state of the photovoltaic storage complementary power supply of the system is divided into three application scenarios: standby, grid-connected and independent load; wherein: In the standby scenario, multiple DC ports are connected to PV panels and batteries respectively, the AC port does not work, and power flows from the PV DC port to the battery DC port; In the grid-connected scenario, it includes any of the following working states: - Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The DC port of the battery is in a charging state, and power is provided by the DC port and AC port of the PV; - Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The DC port of the PV is not working, and the DC port of the battery is in a charging state. Power flows from the AC port to the DC port of the battery. In the independent load scenario, the working status includes any of the following: - Multiple DC ports are connected to the photovoltaic modules and batteries respectively, and the AC ports are connected to the loads, and power flows from the multiple DC ports to the AC ports; -Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads, so that power flows from the DC ports of PV panels to the DC ports and AC ports of batteries; - Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC port of the battery is not working, and the DC port of the PV is in a power generation state. Power flows from the DC port of the PV to the AC port. - Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC ports of PV panels are not working, and the DC ports of batteries are in a discharging state. Power flows from the DC ports of batteries to the AC ports. The control method of the multi-port photovoltaic-storage complementary power supply system constructs a control strategy on the battery side according to the situation that the AC port is connected to the power grid or the AC load, and controls the transmission power of the multi-port photovoltaic-storage complementary power supply system; When the AC port is connected to the grid, the corresponding control strategies include: Generate the grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , get N+M grid-connected current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) ; Wherein, N is the number of photovoltaic modules, and M is the number of batteries; Obtain the grid voltage phase angle θ, and combine the grid voltage phase angle θ and the power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively; Generate external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle; Generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles; By utilizing the obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system and the switching logic of each switch tube of the multi-port photovoltaic-storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system is controlled.

2. The control method according to claim 1, characterized in that: The grid-connected current given value amplitude I of the dual active bridge type micro-inverter connected to the battery by generating M paths m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ,include: Get the battery terminal voltage v bati (i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M), with the battery terminal voltage v bati (i=0,1,…,M) and the battery output current given value I bat,refi (i=0,1,…,M) as input, and calculate the grid-connected current given value amplitude I of the dual active bridge micro-inverter connected to the battery with M paths. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ; in: The battery output current given value I bat,refi (i=0,1,…,M) is obtained based on the battery state of charge, which is negative when the battery is charging and positive when the battery is discharging.

3. The control method according to claim 1 or 2, characterized in that: The external phase angle compensation value ΔD is generated 21b methods, including: A master-slave control method is used to perform closed-loop control on the grid-connected current; wherein the master-slave control method includes: in the multi-port photovoltaic storage complementary power supply system, only one micro-inverter is used as the master to perform current closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master compensates for the distortion of the total grid-connected current; In the grid-connected condition, the N+1th micro-inverter on the battery side is working, and the N+1th micro-inverter is selected as the host. The sum of the instantaneous current given values ​​i g,ref The external phase angle compensation value ΔD is generated by subtracting the actual grid-connected current 21b .

4. The control method according to claim 1, characterized in that: When the AC port is connected to an independent load, the corresponding control strategies include: Generate the grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules respectively m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) , combined with the grid voltage phase angle reference value θ ref , by I g,refi =I m,refi sinθ ref (i=1,2,…,N+M) to obtain the instantaneous current given value I of the multi-port photovoltaic-storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively; Generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the calculated internal and external phase shift angles; By judging the AC side voltage and calculating the gain compensation, the input required for closed-loop control is obtained, and the external phase angle compensation value ΔD is generated under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle; Feedforward calculation is performed according to the no-load startup condition on the AC side, which is used for AC side power control to avoid overvoltage on the AC side; according to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic and energy storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic and energy storage complementary power supply system is controlled.

5. The control method according to claim 4, characterized in that: Also includes: The grid-connected current given value amplitude of the dual active bridge microinverter connected to the photovoltaic module on N paths and the AC side load resistance calculated in real time are used to determine the grid-connected current given value amplitude I of the dual active bridge microinverter connected to the battery on M paths. m,refi (i=N+1,N+2,…,N+M) is: Where: P bat,ref is the battery reference power, P g,ref is the AC side reference power, P pv,ref1 ~P pv,refN is the reference power of N micro-inverters connected to the photovoltaic modules, v d,ref is the AC measurement reference voltage, R L is the equivalent load resistance, I m,ref1 ~I m,rerN is the grid-connected current given value amplitude of N dual active bridge microinverters connected to PV modules, M is the number of batteries; The resistance value of the load resistor on the AC side is calculated in real time according to the sampled voltage and current on the AC side.

6. The control method according to claim 4 or 5, characterized in that: Also includes: Get the AC side voltage given value v g,ref And the AC side voltage sampling value v g , generate the external phase angle compensation value ΔD 21b .

7. A control system for a multi-port photovoltaic-storage complementary power supply system, characterized in that: The multi-port photovoltaic-storage complementary power supply system is constructed based on a one-to-many dual-active bridge micro-inverter structure, including: multiple DC ports, one AC port, multiple DC conversion branches, one AC conversion branch and a multi-winding high-frequency transformer; wherein: Each of the DC conversion branches adopts a full-bridge conversion circuit or a half-bridge conversion circuit; The AC conversion branch includes two bidirectional switch tubes and two non-polar capacitors, the two bidirectional switch tubes are connected in series and then connected in parallel with the two series-connected non-polar capacitors; The primary side of the multi-winding high-frequency transformer is connected to each of the DC conversion branches respectively, and the secondary side of the multi-winding high-frequency transformer is connected to the AC conversion branch; The input end of each of the DC conversion branches is respectively connected to a DC port; The output end of the AC conversion branch is connected to the AC port; Each of the DC ports is used to connect a DC load, a photovoltaic module or a battery, and the AC port is used to connect a power grid or an AC load; according to the connection status and power flow direction of the DC port and the AC port, the working state of the photovoltaic storage complementary power supply of the system is divided into three application scenarios: standby, grid-connected and independent load; wherein: In the standby scenario, multiple DC ports are connected to PV panels and batteries respectively, the AC port does not work, and power flows from the PV DC port to the battery DC port; In the grid-connected scenario, it includes any of the following working states: - Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The DC port of the battery is in a charging state, and power is provided by the DC port and AC port of the PV; - Multiple DC ports are connected to PV panels and batteries respectively, and the AC port is connected to the grid. The DC port of the PV is not working, and the DC port of the battery is in a charging state. Power flows from the AC port to the DC port of the battery. In the independent load scenario, the working status includes any of the following: - Multiple DC ports are connected to the photovoltaic modules and batteries respectively, and the AC ports are connected to the loads, and power flows from the multiple DC ports to the AC ports; -Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads, so that power flows from the DC ports of PV panels to the DC ports and AC ports of batteries; - Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC port of the battery is not working, and the DC port of the PV is in a power generation state. Power flows from the DC port of the PV to the AC port. - Multiple DC ports are connected to PV panels and batteries respectively, and AC ports are connected to loads. The DC ports of PV panels are not working, and the DC ports of batteries are in a discharging state. Power flows from the DC ports of batteries to the AC ports. The control system of the multi-port photovoltaic-storage complementary power supply system constructs a control module on the battery side according to the situation that the AC port is connected to the power grid or the AC load, and controls the transmission power of the multi-port photovoltaic-storage complementary power supply system; when the AC port is connected to the power grid, the corresponding control module includes: an MPPT module, a phase-locked loop module, a battery power set value generation module, a feedforward controller, a current loop and a phase shift controller; wherein: The MPPT module is used to generate a grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the dual active bridge type micro-inverter connected to the battery M-way m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) The grid-connected current given value amplitudes output by the two modules are combined to obtain N+M grid-connected current given value amplitudes I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) ; The phase-locked loop module is used to obtain the grid voltage phase angle θ, and combines the grid voltage phase angle θ and the power factor angle And the grid current given value amplitude I m,ref1 ,I m,ref2 ,…,I m,ref(N+M) , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) and respectively calculating the internal and external phase shift angles of the multi-port photovoltaic storage complementary power supply system through a plurality of the feedforward controllers; The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles; The current loop is used to generate an external phase angle compensation value ΔD 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle; The phase shift controller is used to generate the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the obtained internal and external phase shift angles; The obtained inner phase shift angle and final outer phase shift angle of the multi-port photovoltaic-storage complementary power supply system are used to control the grid-connected current to reach a given value, and control the transmission power between the DC port and the AC port of the multi-port photovoltaic-storage complementary power supply system.

8. The control system according to claim 7, characterized in that: When the AC port is connected to an independent load, the corresponding control module includes: an MPPT module, a battery power set value generation module, a feedforward controller, a feedforward calculation module, a current loop module, a phase shift controller module and a voltage loop module; wherein: The MPPT module is used to generate a grid-connected current set value amplitude I of N dual active bridge micro-inverters connected to photovoltaic modules. m,ref1 ,I m,ref2 ,…,I m,refN The battery power given value generation module is used to generate the grid-connected current given value amplitude I of the M-way dual active bridge type micro-inverter connected to the battery according to the grid-connected current given value amplitude of the N-way dual active bridge type micro-inverter connected to the photovoltaic module. m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) ; The feedforward controller is used to set the grid-connected current set value amplitude I of the N dual active bridge micro-inverters connected to the photovoltaic components. m,ref1 ,I m,ref2 ,…,I m,refN The grid-connected current set value amplitude I of the dual active bridge micro-inverter connected to the battery with M circuits m,ref(N+1) ,I m,ref(N+2) ,…,I m,ref(N+M) Combined with the grid voltage phase angle reference value θ ref , and obtain the instantaneous current given value I of the multi-port photovoltaic storage complementary power supply system g,ref1 ,I g,ref2 ,…,I g,ref(N+M) , and calculate the internal and external phase shift angles of the multi-port photovoltaic storage complementary power system respectively; The phase shift controller module generates the switching logic of each switch tube of the multi-port photovoltaic storage complementary power supply system according to the calculated internal and external phase shift angles; The current loop module obtains the input required for closed-loop control through AC side voltage judgment and gain compensation calculation, which is used to implement closed-loop control; The voltage loop module is used to generate an external phase angle compensation value ΔD under closed-loop control. 21b , and the external phase angle compensation value ΔD 21b Added with the external shift phase angle to generate the final external shift phase angle; The feedforward calculation module is used to perform feedforward calculation according to the no-load startup condition of the AC side, so as to avoid overvoltage on the AC side; According to the obtained inner phase shift angle and the final outer phase shift angle, based on the switching logic of each switch tube of the multi-port photovoltaic and energy storage complementary power supply system, the grid-connected current is controlled to reach a given value, and the transmission power between the DC port and the AC port of the multi-port photovoltaic and energy storage complementary power supply system is controlled.

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