A multi-port current source type non-common ground type photovoltaic storage complementary system and control method

Abstract

The present invention provides a multi-port current source non-common ground type photovoltaic-storage complementary system, comprising: multiple DC ports, an AC port, multiple DC-AC conversion branches, an AC-AC conversion branch and a multi-winding high-frequency transformer. The system establishes a hardware-based power decoupling solution by designing the leakage inductance value, the excitation inductance value and the capacitance value of the AC-AC conversion branch of the multi-port high-frequency transformer, realizes power decoupling between multiple DC ports and AC ports, and solves the circulation problem between the ports. The present invention also provides a control method for the above photovoltaic-storage complementary system, which divides the working state of the photovoltaic-storage complementary system into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction, and changes the corresponding control strategy according to different working conditions, so that the photovoltaic-storage complementary system can still ensure stable operation when facing complex actual working conditions, thereby improving the reliability of the photovoltaic-storage complementary system.

Description

Technical Field

[0001] The present invention relates to the field of multi-port current source photovoltaic-storage complementary systems, and in particular to a multi-port current source non-common ground photovoltaic-storage complementary system and a control method. Background Art

[0002] The photovoltaic-storage complementary power supply is a portable charger that can be carried around, store electrical energy, and output AC and DC. It is especially used in situations where there is no external power supply. Its main components include: a battery for energy storage, a circuit for stabilizing the output voltage, and a charger circuit for charging the built-in battery. The multi-port DC-AC converter has the advantages of multiple inputs, multiple outputs, and bidirectional energy flow, so it can be combined with energy storage as a photovoltaic-storage complementary mobile power converter.

[0003] The parameter coupling of different ports of the existing multi-port DC-AC converter is relatively complex. If the coupling relationship between different ports is ignored and only the relationship between the parameters of a single port is controlled, the control outputs of different ports will interact with each other, reducing the dynamic performance of the multi-port conversion system, and reducing the control speed and accuracy of the system. Therefore, it is necessary to study the control scheme suitable for multi-port DC-AC converters. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a multi-port current source photovoltaic storage complementary system and a control method.

[0005] A first aspect of the present invention provides a multi-port current source non-common ground type photovoltaic energy storage complementary system, comprising a plurality of DC ports, an AC port, a plurality of DC-AC conversion branches, an AC-AC conversion branch and a multi-winding high-frequency transformer;

[0006] The multiple DC ports are connected to photovoltaic panel assemblies or batteries, the DC port connected to the photovoltaic panel assembly is a photovoltaic DC port, the DC port connected to the battery is a battery DC port, and the one AC port can be connected to a power grid or a load;

[0007] The AC ports of the multiple DC-AC conversion branches and the high-frequency AC port of one AC-AC conversion branch are respectively connected to multiple ports of the multi-winding high-frequency transformer; each DC-AC conversion branch and the AC-AC conversion branch form a micro-inverter;

[0008] The leakage inductance of each port of the multi-port high-frequency transformer is L ky , the excitation inductance of each port is L my ,subscript y=1,2,...,n+m+1, the turns ratios of each winding are n1:n2:...:n (n+m+1); Where n is the number of PV DC ports, and m is the number of battery DC ports;

[0009] The AC-AC conversion branch includes switch tubes Q1-Q4 and film capacitors C1 and C2;

[0010] The DC-AC conversion branch is connected to the input capacitor C in and an interleaved parallel Buck / Boost circuit; the interleaved parallel Buck / Boost circuit includes an inductor L 1i and L 2i , switch tube S 1i ~S 4i and clamping capacitor C bus1 or C bus2 , where subscript i = 1, 2, ..., n + m, and the clamping capacitor of the DC-AC conversion branch where the photovoltaic DC port is located is C bus1 , the clamping capacitor of the DC-AC conversion branch where the battery DC port is located is C bus2 ;

[0011] In the staggered parallel Buck / Boost circuit, the switch tube S 1i The source and switch tube S 2i The drain is connected to the inductor L 1i One end of the switch tube S 3i The source and switch tube S 4i The drain is connected to the inductor L 2i One end of the switch tube S 1i The drain and switch S 3i The drain of the bus1 or C bus2 The positive electrode of the switch tube S 2i The source and switch tube S 4i The source of the capacitor C bus1 or C bus2 The negative pole is connected;

[0012] In the AC-AC conversion branch, 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, 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, and the negative electrode of the film capacitor C1 is connected to the positive electrode of the film capacitor C2.

[0013] Optionally, the photovoltaic-storage complementary system is divided into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction; wherein:

[0014] - Standby scene conditions:

[0015] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state. The AC port is not working, and power flows from the photovoltaic DC port to the battery DC port.

[0016] -Grid-connected scenarios include any of the following specific conditions:

[0017] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port and the AC port to the battery DC port.

[0018] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port.

[0019] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port.

[0020] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port is not working, and the battery DC port is in a charging state. Power flows from the AC port to the battery DC port.

[0021] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic 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;

[0022] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port.

[0023] -Independent load scenarios include any of the following specific conditions:

[0024] Multiple DC ports are connected to photovoltaic modules and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port.

[0025] Multiple DC ports are connected to photovoltaic modules and batteries respectively, and AC ports are connected to independent loads. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port.

[0026] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the independent load. The photovoltaic DC port is not working, the battery DC port is in a discharge state, and the power flows from the battery DC port to the AC port;

[0027] Multiple DC ports are connected to photovoltaic panel components and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port.

[0028] A second aspect of the present invention provides a control method for the multi-port current source type non-common ground type photovoltaic storage complementary system, comprising:

[0029] The battery management system monitors the battery state of charge in real time, sorts the battery state of charge, and performs charge balance control on multiple battery DC ports according to the battery state of charge.

[0030] When the power direction of the battery DC port is flowing into the battery, that is, the battery is in a charging state, the battery with a low state of charge is charged first;

[0031] When the power direction of the battery DC port is to flow out of the battery, that is, when the battery is in a discharging state, the battery with a higher state of charge is discharged first.

[0032] Optionally, the control strategy of the battery side is changed according to whether the AC port is connected to the grid or an independent load, wherein the control strategy is any one of the following:

[0033] -When the AC port is connected to the grid, the control strategy includes:

[0034] The MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter. m,refi , I m,refi Subscript i=1,2,...,n+m;

[0035] In the battery power setpoint module, v batj is the battery terminal voltage; I bat,refj is the given value of the battery output current, obtained based on the battery state of charge, which is negative when the battery is charging and positive when the battery is discharging; subscript j = 1, 2, ..., m;

[0036] The phase-locked loop module is used to obtain the grid voltage phase angle θ, and the power factor angle I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi ,i g,refi Subscript i = 1, 2, ..., n + m, and multiple feedforward controllers are used to calculate the internal phase shift angle D of the multiple micro-inverters respectively. 1i and the outward phase angle D 2i ;

[0037] The AC port 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 AC port current;

[0038] Select the n+1th micro-inverter as the host, and the total AC port current given value i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1),cal After adding, the final external shift phase angle D is generated 2(n+1) ;

[0039] When the AC port is connected to an independent load, the control strategy includes:

[0040] The MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m;

[0041] In the battery power setpoint module, v batj is the battery terminal voltage; α j is the battery output current given value coefficient, obtained based on the battery charge state; subscript j = 1, 2, ..., m;

[0042] The given value of the AC port current phase angle is θ ref , combined with θ ref ,I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi , and calculate the internal phase shift angle D of the multi-channel micro-inverters respectively through multiple feedforward controllers 1i and the outward phase angle D2i ; Subscript i=1,2,...,n+m;

[0043] The AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter is used as the master to perform voltage closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master performs gain compensation on the AC port voltage;

[0044] The battery power setpoint module sets the current amplitude setpoint I of the multi-channel micro-inverter AC port according to the output of the MPPT module. m,refi , the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,ref And the battery output current given value coefficient α j Determine the current amplitude given value I of the AC port of the j-th micro-inverter m,refk , subscript k = n+1, n+2, ..., n+m.

[0045] The third aspect of the present invention provides a control device for the multi-port current source type non-common ground type photovoltaic storage complementary system. When the AC port is connected to the power grid, the control device includes an MPPT module, a voltage loop module, a phase-locked loop module, a battery power set value module, a multi-channel micro-inverter feedforward controller, a current controller and a phase shift controller; wherein,

[0046] The MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m;

[0047] In the battery power given value module, the battery terminal voltage v is obtained based on the battery charge state batj and the battery output current given value I bat,refj , which is negative when the battery is charging and positive when the battery is discharging; subscript j = 1, 2, ..., m;

[0048] The grid voltage phase angle θ can be obtained through the phase-locked loop module, and the power factor angle I m,refi The instantaneous current given value i of the multi-channel micro-inverter can be obtained g,refi and respectively calculate the internal and external phase shift angles of the multiple micro-inverters through the multiple micro-inverter feedforward controller; subscript i=1,2,...,n+m;

[0049] The AC port 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 AC port current;

[0050] Select the n+1th micro-inverter as the host, and the total AC port current given value i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1),cal After adding, the final external shift phase angle D is generated 2(n+1) ;

[0051] Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ; Wherein subscript x=1,2,...,n;

[0052] The phase shift controller is based on the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

[0053] The fourth aspect of the present invention provides a control device for the multi-port current source type non-common ground type photovoltaic storage complementary system. When the AC port is connected to an independent load, the control device includes: an MPPT module, a voltage loop module, a battery power set value module, a multi-channel micro-inverter feedforward calculation module, a voltage controller and a phase shift controller; wherein,

[0054] The MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m;

[0055] In the battery power given value module, v batj is the battery terminal voltage; α j is the battery output current given value coefficient, obtained based on the battery charge state; subscript j = 1, 2, ..., m;

[0056] The given value of the AC port current phase angle is θ ref , combined with θ ref ,I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi and respectively calculate the internal and external phase shift angles of the multi-channel micro-inverters through the multi-channel micro-inverter feedforward calculation module; subscript i=1,2,...,n+m;

[0057] The AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter is used as the master to perform voltage closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master performs gain compensation on the AC port voltage;

[0058] The battery power setpoint module sets the current amplitude setpoint I of the multi-channel micro-inverter AC port according to the output of the MPPT module. m,refi , the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,ref And the battery output current given value coefficient α j Determine the current amplitude given value I of the AC port of the i-th micro-inverter m,refk , subscript k = n+1, n+2, ..., n+m;

[0059] Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ; Wherein subscript x=1,2,...,n;

[0060] The phase shift controller is based on the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

[0061] 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:

[0062] The multi-port current source non-common ground type photovoltaic storage complementary system provided by the present invention applies the current source dual active bridge type micro-inverter to the application scenario of the photovoltaic storage complementary system, so that the one-to-many micro-inverter (one AC port, multiple photovoltaic / battery DC ports) has a higher practical value.

[0063] The multi-port current source non-common ground type photovoltaic storage complementary system provided by the present invention realizes power decoupling between multiple DC ports and AC ports, and solves the circulation problem between the ports.

[0064] The control method of the multi-port current source non-common-ground photovoltaic-storage complementary system provided by the present invention divides the working state of the photovoltaic-storage complementary system into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction, and changes the corresponding control strategy according to different working conditions, so that the photovoltaic-storage complementary system can still ensure stable operation when facing complex actual working conditions, thereby improving the reliability of the photovoltaic-storage complementary system. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] 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:

[0066] Figure 1 It is a schematic diagram of a multi-port current source type non-common ground type photovoltaic storage complementary system in a preferred embodiment of the present invention;

[0067] Figure 2 This is an overall control block diagram of a multi-port current source type non-common ground type photovoltaic storage complementary system under grid-connected conditions in a preferred embodiment of the present invention;

[0068] Figure 3 This is an overall control block diagram of a multi-port current source type non-common ground type photovoltaic storage complementary system under independent load conditions in a preferred embodiment of the present invention;

[0069] Figure 4 This is a real-time load calculation flow chart of a multi-port current source non-common-ground photovoltaic-storage complementary system under independent load conditions in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0070] 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.

[0071] The parameter coupling of different ports of the existing multi-port DC-AC converter is relatively complex. If the coupling relationship between different ports is ignored and only the mutual relationship of the parameters of a single port is controlled, the control outputs of different ports will interact with each other, reducing the dynamic performance of the multi-port conversion system, and reducing the control speed and accuracy of the system. To this end, an embodiment of the present invention provides a multi-port current source non-common ground type photovoltaic storage complementary system, which can solve the above problems.

[0072] Figure 1 It is a schematic diagram of a multi-port current source type non-common ground type photovoltaic storage complementary system in a preferred embodiment of the present invention;

[0073] Reference Figure 1 As shown, this embodiment provides a multi-port current source photovoltaic storage complementary system. In this embodiment, the multi-port current source converter system architecture includes multiple DC ports, one AC port, multiple DC-AC conversion branches, one AC-AC conversion branch and a multi-winding high-frequency transformer;

[0074] Multiple DC ports can be connected to photovoltaic panel assemblies or batteries. The DC port connected to the photovoltaic panel assembly is a photovoltaic DC port, the DC port connected to the battery is a battery DC port, and one AC port can be connected to a grid or a load.

[0075] The AC ports of a plurality of DC-AC conversion branches and the high-frequency AC port of an AC-AC conversion branch are respectively connected to a plurality of ports of a multi-winding high-frequency transformer;

[0076] The leakage inductance of each port of the multi-port high-frequency transformer is L ky (y=1,2,...,n+m+1), the excitation inductance of each port is L my (i=1,2,...,n+m+1), the turns ratios of each winding are n1:n2:...:n (n+m+1) ;

[0077] The AC-AC conversion branch includes switch tubes Q1 to Q4 and film capacitors C1 and C2;

[0078] The DC-AC conversion branch is routed by the input capacitor C in And interleaved parallel Buck / Boost circuit;

[0079] The interleaved parallel Buck / Boost circuit includes the inductor L 1i and L 2i (i=1,2,...,n+m), switch tube S 1i ~S 4i (i=1,2,...,n+m) and clamping capacitor C bus1 , C bus2 Each DC-AC conversion branch uses a clamping capacitor. The clamping capacitor of the DC-AC conversion branch where the photovoltaic DC port is located is C bus1 , the clamping capacitor of the DC-AC conversion branch where the battery DC port is located is C bus2 , to reflect the different values ​​of the clamping capacitors of the two DC-AC conversion branches.

[0080] In the interleaved parallel Buck / Boost circuit, the switch tube S 1i The source and switch tube S 2i The drain is connected to the inductor L 1i (i=1,2,...,n+m) is connected to one end, and the switch tube S 3i The source and switch tube S 4i The drain is connected to the inductor L 2i (i=1,2,...,n+m) is connected to one end, and the switch tube S 1i The drain and switch S 3i The drain of the bus1 or C bus2 The positive electrode of the switch tube S 2i The source and switch tube S 4i The source of the capacitor C bus1 or C bus2 The negative pole is connected;

[0081] In the AC-AC conversion branch, 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, 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, and the negative electrode of the film capacitor C1 is connected to the positive electrode of the film capacitor C2.

[0082] In the above embodiment, the current source dual active bridge micro-inverter is applied to the photovoltaic storage complementary system, which can realize power decoupling between multiple DC ports and AC ports, and solve the circulation problem between the ports. Specifically, by designing the leakage inductance value, excitation inductance value and capacitance value of the AC-AC conversion branch of each port of the multi-port high-frequency transformer, a hardware-based power decoupling solution is established to realize power decoupling between multiple DC ports and AC ports.

[0083] Specifically, the excitation inductance of each port of the multi-port high-frequency transformer is much larger than the leakage inductance of the corresponding port, satisfying L mi >10*L ki (i=1,2,...,n+m); leakage inductance L of the transformer port connected to the AC-AC branch k(n+m+1) Should be small enough; the capacitance values ​​C1 and C2 in the AC-AC conversion branch should be large enough. And meet the following requirements:

[0084]

[0085] Among them, ω s is the angular frequency of the switching frequency. j is the sign of the imaginary number.

[0086] Specifically, after power decoupling, the power circulation between the DC ports is resolved, and the control between the DC ports is also decoupled.

[0087] The multi-port current source photovoltaic-storage complementary system in the above embodiment of the present invention can divide the working state of the photovoltaic-storage complementary system into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction.

[0088] The following table shows the application scenarios and specific working conditions of the multi-port current source photovoltaic storage complementary system in a preferred embodiment of the present invention:

[0089]

[0090] According to the above table, various working conditions are described as follows:

[0091] Standby scene conditions:

[0092] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state. The AC port is not working, and power flows from the photovoltaic DC port to the battery DC port.

[0093] The grid-connected scenario includes any of the following specific conditions:

[0094] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port and the AC port to the battery DC port.

[0095] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port.

[0096] Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port.

[0097] Multiple DC ports are respectively connected to the photovoltaic panel assembly and the battery, the AC port is connected to the power grid, the photovoltaic DC port is not working, the battery DC port is in a charging state, and power flows from the AC port to the battery DC port.

[0098] Multiple DC ports are respectively connected to the photovoltaic panel assembly and the battery, and the AC port is connected to the power grid. The photovoltaic 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.

[0099] Multiple DC ports are respectively connected to the photovoltaic panel components and the battery, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port.

[0100] Independent load scenarios include any of the following specific conditions:

[0101] Multiple DC ports are connected to photovoltaic modules and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port.

[0102] Multiple DC ports are connected to photovoltaic modules and batteries respectively, and AC ports are connected to independent loads. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port.

[0103] Multiple DC ports are respectively connected to the photovoltaic panel assembly and the battery, and the AC port is connected to the independent load. The photovoltaic 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.

[0104] Multiple DC ports are connected to photovoltaic panel components and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port.

[0105] In the above embodiments of the present invention, the working state of the photovoltaic-storage complementary system is divided into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction. The corresponding control strategy can be changed according to different working conditions, so that the photovoltaic-storage complementary system can still ensure stable operation when facing complex actual working conditions, thereby improving the reliability of the photovoltaic-storage complementary system.

[0106] Based on the multi-port current source type common ground photovoltaic storage complementary system in the above embodiment, in order to perform control for different application scenarios, another embodiment of the present invention also provides a corresponding control method.

[0107] Specifically, an embodiment of the present invention also provides a control method for a multi-port current source type common ground type photovoltaic storage complementary system, the method comprising: monitoring the battery state of charge in real time through a battery management system, sorting the battery state of charge, and performing charge balance control on multiple battery DC ports according to the level of the battery state of charge. When the power direction of the battery DC port is flowing into the battery, that is, the battery is in a charging state, the battery with a low state of charge is charged first; when the power direction of the battery DC port is flowing out of the battery, that is, the battery is in a discharging state, the battery with a high state of charge is discharged first. This control method is conducive to maintaining the balance of the state of charge of batteries at different battery DC ports.

[0108] Based on the above embodiments, in the control method of the present invention, the control strategy of the battery side can be changed according to the situation that the AC port is connected to the grid or an independent load.

[0109] Specifically, the present invention provides a control method for the above-mentioned multi-port current source photovoltaic-storage complementary system. According to the connection status of the AC and DC ports and the power flow direction, the method can divide the working state of the photovoltaic-storage complementary system into three application scenarios: standby, grid-connected and independent load.

[0110] Specifically, Figure 2 As shown, in some embodiments, when the AC port is connected to the power grid, the control strategy includes the following steps:

[0111] S11, the MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter m,refi (i=1,2,...,n+m);

[0112] S12, battery power given value module, v batj (j=1,2,...,m) is the battery terminal voltage; I bat,refj (j=1, 2, ..., m) is a given value of the battery output current, which can be obtained based on the battery state of charge, and is negative when the battery is charging and positive when the battery is discharging.

[0113] S13, the grid voltage phase angle θ can be obtained through the phase-locked loop module, combined with θ and the power factor angle I m,refi (i=1,2,...,n+m) can get the instantaneous current given value i of multiple micro-inverters g,refi (i=1,2,...,n+m), and calculate the internal and external phase shift angles of the multi-channel micro-inverters respectively through multiple feedforward controllers.

[0114] S14, the AC port current closed-loop control adopts a master-slave control mode, that is, only one micro-inverter acts as the master to perform current closed-loop control, and the other micro-inverters act as slaves to perform only feedforward control, and the master compensates for the distortion of the total AC port current.

[0115] S15, select the n+1th micro-inverter as the host, and the total AC port current is given as i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1) ,cal are added to generate the final external phase angle D 2(n+1) .

[0116] Reference Figure 2 , where i pvx (x=1,2,…,n) is the output current of the photovoltaic DC port, v pvx (x=1,2,…,n) is the PV DC port voltage, V pv,refx (x=1,2,…,n) is the reference value of the PV DC port voltage, v g is the AC port voltage, i g is the AC port current, u α and u βare the components of the AC port voltage in the orthogonal coordinate system, PLL is the phase-locked loop module, SOGI is the second-order generalized integrator, S 1i ~S 4i , Q1~Q4 (i=1,2,…,n+m) respectively represent the PWM signals of the corresponding switching tubes.

[0117] The control method of the above embodiment can realize the maximum power point tracking of the photovoltaic panel assembly, realize grid-side power control by controlling the grid-side current, realize battery power control, complete the power transmission of the photovoltaic DC port, the battery DC port and the AC port, and compensate for the distortion of the total AC port current through the current controller, thereby optimizing the current waveform.

[0118] Specifically, Figure 3 As shown, in some embodiments, when the AC port is connected to an independent load, the control strategy includes the following steps:

[0119] S21, the MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter m,refi (i=1,2,...,n+m);

[0120] S22, battery power given value module, v batj (j=1,2,...,m) is the battery terminal voltage; α j (j=1, 2, ..., m) is a battery output current given value coefficient, which can be obtained based on the battery state of charge.

[0121] S23, the given value of the AC port current phase angle is θ ref , combined with θ ref ,I m,refi (i=1,2,...,n+m) can get the instantaneous current given value i of multiple micro-inverters g,refi (i=1,2,...,n+m), and calculate the internal and external phase shift angles of the multi-channel micro-inverters respectively through multiple feedforward controllers.

[0122] S24, the AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter acts as the master to perform voltage closed-loop control, and the other micro-inverters act as slaves to perform only feedforward control, and the master performs gain compensation on the AC port voltage.

[0123] S25, the battery power given value module needs to set the current amplitude given value I of the AC port of the multi-channel micro-inverter output by the MPPT module m,refi (i=1,2,...,n+m), the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,refAnd the battery output current given value coefficient α j (j=1,2,...,m) Determine the given value I of the current amplitude of the AC port of the j-th micro-inverter m,refk (i=n+1,n+2,...,n+m), the calculation expression is:

[0124]

[0125] Among them, P g,ref is the AC port power reference value, P pv,ref It is the total power reference value of the PV DC port.

[0126] Among them, the control method under the independent load condition needs to calculate the load resistance value on the AC side in real time, and the method is to calculate the load resistance based on the sampled voltage and sampled current on the AC side.

[0127] Figure 3 in,i pvx (x=1,2,…,n) is the output current of the photovoltaic DC port, v pvx (x=1,2,…,n) is the PV DC port voltage, V pv ,refx(x=1,2,…,n) is the reference value of the PV DC port voltage, v g is the AC port voltage, v g,ref is the AC port voltage reference value, S 1i ~S 4i , Q1~Q4 (i=1,2,…,n+m) respectively represent the PWM signals of the corresponding switching tubes.

[0128] The control method in the above embodiment can realize maximum power point tracking of photovoltaic panel assemblies, realize grid-side power control by controlling grid-side current, realize battery power control, complete power transmission of photovoltaic DC port, battery DC port and AC port, and perform gain compensation on AC port voltage through voltage controller, thereby optimizing voltage waveform.

[0129] Based on Figure 2 The same technical concept as the embodiment shown, when the AC port is connected to the power grid, an embodiment of the present invention also provides a control device for the above-mentioned photovoltaic storage complementary system, including an MPPT module, a voltage loop module, a phase-locked loop module, a battery power set value module, a multi-channel micro-inverter feedforward controller, a current controller and a phase shift controller. The MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter m,refi (i=1,2,...,n+m); in the battery power given value module, v batj (j=1,2,...,m) is the battery terminal voltage; I bat,refj(j=1,2,...,m) 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 module. Combining θ and the power factor angle I m,refi (i=1,2,...,n+m) can get the instantaneous current given value i of multiple micro-inverters g,refi (i=1,2,...,n+m), and calculate the internal and external phase shift angles of multiple micro-inverters respectively through multiple feedforward controllers. The AC port 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 AC port current. The n+1th micro-inverter is selected as the master, and the total AC port current given value i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1),cal After adding, the final external shift phase angle D is generated 2(n+1) . Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ; Phase shift controller, according to the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

[0130] Based on Figure 3 The same technical concept as the embodiment shown, when the AC port is connected to an independent load, an embodiment of the present invention also provides a control device for the above-mentioned photovoltaic storage complementary system, including: an MPPT module, a voltage loop module, a battery power set value module, a multi-channel micro-inverter feedforward calculation module, a voltage controller and a phase shift controller. The MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter m,refi (i=1,2,...,n+m); in the battery power given value module, v batj (j=1,2,...,m) is the battery terminal voltage; α j (j=1,2,...,m) is the battery output current given value coefficient, which can be obtained based on the battery charge state. The AC port current phase angle given value is θ ref , combined with θ ref ,I m,refi (i=1,2,...,n+m) can get the instantaneous current given value i of multiple micro-inverters g,refi(i=1,2,...,n+m), and calculate the internal and external phase shift angles of multiple micro-inverters respectively through multiple feedforward controllers. The AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter is used as the host to perform voltage closed-loop control, and the other micro-inverters are used as slaves to perform feedforward control only, and the host performs gain compensation on the AC port voltage. The battery power setpoint module needs to set the AC port current amplitude setpoint I of the multiple micro-inverters output by the MPPT module. m,refi (i=1,2,...,n+m), the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,ref And the battery output current given value coefficient α j (j=1,2,...,m) Determine the given value I of the AC port current amplitude of the i-th micro-inverter m,refk (k=n+1,n+2,...,n+m). Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ; Phase shift controller, according to the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

[0131] Specifically, in the above embodiment, the current amplitude of the AC port of the k-th micro-inverter is given by I m,refk (k=n+1,n+2,...,n+m), its calculation expression is:

[0132]

[0133] Among them, the control method under the independent load condition needs to calculate the load resistance value on the AC side in real time, and the method is to calculate the load resistance based on the sampled voltage and sampled current on the AC side.

[0134] Figure 4 This is a real-time load calculation flow chart for a multi-port current source non-common ground photovoltaic storage complementary system 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 4As shown in the figure, the basic idea of ​​real-time calculation of load resistance is to calculate the load resistance according to the AC side sampling voltage and sampling current, and use the calculated load resistance value for feedforward calculation. At startup, since the AC side voltage is not established, 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 startup situation, so that the machine is in a heavy load condition at startup to avoid overvoltage on the AC side.

[0135] In the above embodiments of the present invention, the photovoltaic-storage complementary system has multiple application scenarios. According to the power flow direction, it can be divided into three categories of application scenarios, namely standby, grid-connected and independent load conditions, and corresponding control methods and control devices are designed for each condition, so that the photovoltaic-storage complementary system can still ensure stable operation when facing complex actual conditions, thereby improving the reliability of the photovoltaic-storage complementary system.

[0136] 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 can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred technical features can be used in any combination without conflicting with each other.

Claims

1. A multi-port current source type non-co-ground type photovoltaic storage complementary system, characterized by: It includes a plurality of DC ports, an AC port, a plurality of DC-AC conversion branches, an AC-AC conversion branch and a multi-winding high-frequency transformer; The multiple DC ports are connected to photovoltaic panel assemblies or batteries, the DC port connected to the photovoltaic panel assembly is a photovoltaic DC port, the DC port connected to the battery is a battery DC port, and the one AC port can be connected to a power grid or a load; The AC ports of the multiple DC-AC conversion branches and the high-frequency AC port of one AC-AC conversion branch are respectively connected to multiple ports of the multi-winding high-frequency transformer; each DC-AC conversion branch and the AC-AC conversion branch form a micro-inverter; The leakage inductance of each port of the multi-port high-frequency transformer is L ky , the excitation inductance of each port is L my ,subscript y=1,2,...,n+m+1, the turns ratios of each winding are n1:n2:...:n (n+m+1) ; Where n is the number of PV DC ports, and m is the number of battery DC ports; The AC-AC conversion branch includes switch tubes Q1-Q4 and film capacitors C1 and C2; The DC-AC conversion branch is connected to the input capacitor C in and an interleaved parallel Buck / Boost circuit; the interleaved parallel Buck / Boost circuit includes an inductor L 1i and L 2i , switch tube S 1i ~S 4i and clamping capacitor C bus1 or C bus2 , where subscript i = 1, 2, ..., n + m, and the clamping capacitor of the DC-AC conversion branch where the photovoltaic DC port is located is C bus1 , the clamping capacitor of the DC-AC conversion branch where the battery DC port is located is C bus2 ; In the staggered parallel Buck / Boost circuit, the switch tube S 1i The source and switch tube S 2i The drain is connected to the inductor L 1i One end of the switch tube S 3i The source and switch tube S 4i The drain is connected to the inductor L 2i One end of the switch tube S 1i The drain and switch S 3i The drain of the bus1 or C bus2 The positive electrode of the switch tube S 2i The source and switch tube S 4i The source of the capacitor C bus1 or C bus2 The negative pole is connected; In the AC-AC conversion branch, 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, 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, and the negative electrode of the film capacitor C1 is connected to the positive electrode of the film capacitor C2; The power decoupling between the multiple DC ports and the AC ports adopts hardware-based power decoupling, and the hardware-based power decoupling is established according to the leakage inductance value, the excitation inductance value and the capacitance value of the AC-AC conversion branch of each port of the multi-port high-frequency transformer; The excitation inductance of each port of the multi-port high-frequency transformer is greater than the leakage inductance of the corresponding port, satisfying L mi >10*L ki , i=1,2,...,n+m; leakage inductance L of the transformer port connected to the AC-AC branch k(n+m+1) Small enough; the capacitance values ​​C1 and C2 in the AC-AC conversion branch are large enough. Specifically, the above parameters satisfy the following formula: Among them, ω s is the angular frequency of the switching frequency, and j is the sign of the imaginary number.

2. The multi-port current source non-co-ground type photovoltaic storage complementary system according to claim 1 is characterized in that: After power decoupling, there is no power circulation between the DC ports, and the control between the DC ports is decoupled.

3. The multi-port current source non-common ground type photovoltaic storage complementary system according to claim 1, characterized in that: The photovoltaic storage complementary system is divided into three application scenarios: standby, grid-connected and independent load according to the connection status of the AC and DC ports and the power flow direction; wherein: - Standby scene conditions: Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state. The AC port is not working, and power flows from the photovoltaic DC port to the battery DC port. -Grid-connected scenarios include any of the following specific conditions: Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port is operated at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port and the AC port to the battery DC port. Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port. Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port. Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port is not working, and the battery DC port is in a charging state. Power flows from the AC port to the battery DC port. Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic 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; Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the power grid. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port. -Independent load scenarios include any of the following specific conditions: Multiple DC ports are connected to photovoltaic modules and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a discharging state, and power flows from the photovoltaic DC port and the battery DC port to the AC port. Multiple DC ports are connected to photovoltaic modules and batteries respectively, and AC ports are connected to independent loads. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharging state. The battery DC port is in a charging state, and power flows from the photovoltaic DC port to the battery DC port and the AC port. Multiple DC ports are connected to the photovoltaic panel assembly and the battery respectively, and the AC port is connected to the independent load. The photovoltaic DC port is not working, the battery DC port is in a discharge state, and the power flows from the battery DC port to the AC port; Multiple DC ports are connected to photovoltaic panel components and batteries respectively, and the AC port is connected to an independent load. The photovoltaic DC port operates at the maximum power point through maximum power point tracking control and is in a discharge state. The battery DC port does not work, and power flows from the photovoltaic DC port to the AC port.

4. A control method for the multi-port current source non-co-grounded photovoltaic storage complementary system according to claim 3, characterized in that: include: The battery management system monitors the battery state of charge in real time, sorts the battery state of charge, and performs charge balance control on multiple battery DC ports according to the battery state of charge. When the power direction of the battery DC port is flowing into the battery, that is, the battery is in a charging state, the battery with a low state of charge is charged first; When the power direction of the battery DC port is to flow out of the battery, that is, when the battery is in a discharging state, the battery with a higher state of charge is discharged first.

5. The control method according to claim 4, characterized in that: According to the situation that the AC port is connected to the grid or an independent load, the control strategy of the battery side is changed, wherein the control strategy is any one of the following: -When the AC port is connected to the grid, the control strategy includes: The MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter. m,refi , I m,refi Subscript i=1,2,...,n+m; In the battery power setpoint module, v batj is the battery terminal voltage; I bat,refj is the given value of the battery output current, obtained based on the battery state of charge, which is negative when the battery is charging and positive when the battery is discharging; subscript j = 1, 2, ..., m; The phase-locked loop module is used to obtain the grid voltage phase angle θ, and the power factor angle I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi ,i g,refi Subscript i = 1, 2, ..., n + m, and multiple feedforward controllers are used to calculate the internal phase shift angle D of the multiple micro-inverters respectively. 1i and the outward phase angle D 2i ; The AC port 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 AC port current; Select the n+1th micro-inverter as the host, and the total AC port current given value i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1),cal After adding, the final external shift phase angle D is generated 2(n+1) ; When the AC port is connected to an independent load, the control strategy includes: The MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m; In the battery power setpoint module, v batj is the battery terminal voltage; α j is the battery output current given value coefficient, obtained based on the battery charge state; subscript j = 1, 2, ..., m; The given value of the AC port current phase angle is θ ref , combined with θ ref ,I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi , and calculate the internal phase shift angle D of the multi-channel micro-inverters respectively through multiple feedforward controllers 1i and the outward phase angle D 2i ; Subscript i=1,2,...,n+m; The AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter is used as the master to perform voltage closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master performs gain compensation on the AC port voltage; The battery power setpoint module sets the current amplitude setpoint I of the multi-channel micro-inverter AC port according to the output of the MPPT module. m,refi , the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,ref And the battery output current given value coefficient α j Determine the current amplitude given value I of the AC port of the j-th micro-inverter m,refk， Subscript k = n+1, n+2, ..., n+m.

6. The control method according to claim 5, characterized in that: Under independent load conditions, the AC side load resistance is calculated in real time, and the method is to calculate the load resistance according to the AC port sampling voltage and sampling current.

7. A control device for a multi-port current source non-common ground photovoltaic storage complementary system as claimed in claim 3, characterized in that: When the AC port is connected to the power grid, the control device includes an MPPT module, a voltage loop module, a phase-locked loop module, a battery power setpoint module, a multi-channel micro-inverter feedforward controller, a current controller and a phase shift controller; wherein, The MPPT module and the battery power set value module respectively generate the AC port current set value amplitude I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m; In the battery power given value module, the battery terminal voltage v is obtained based on the battery charge state batj and the battery output current given value I bat,refj , which is negative when the battery is charging and positive when the battery is discharging; subscript j = 1, 2, ..., m; The grid voltage phase angle θ can be obtained through the phase-locked loop module, and the power factor angle I m,refi The instantaneous current given value i of the multi-channel micro-inverter can be obtained g,refi and respectively calculate the internal and external phase shift angles of the multiple micro-inverters through the multiple micro-inverter feedforward controller; subscript i=1,2,...,n+m; The AC port 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 AC port current; Select the n+1th micro-inverter as the host, and the total AC port current given value i g,ref and the actual AC port current i g After the difference is made, the external phase angle compensation value ΔD is generated by the current controller 2(n+1) , and the calculated value of the external shift phase angle D 2(n+1),cal After adding, the final external shift phase angle D is generated 2(n+1) ; Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ; Subscript x = 1, 2, ..., n; The phase shift controller is based on the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

8. A control device for a multi-port current source non-common ground photovoltaic storage complementary system as claimed in claim 3, characterized in that: When the AC port is connected to an independent load, the control device includes: an MPPT module, a voltage loop module, a battery power set value module, a multi-channel micro-inverter feedforward calculation module, a voltage controller and a phase shift controller; wherein, The MPPT module and the battery power set value module respectively generate the AC port current amplitude set value I of the multi-channel micro-inverter. m,refi , subscript i=1,2,...,n+m; In the battery power given value module, v batj is the battery terminal voltage; α j is the battery output current given value coefficient, obtained based on the battery charge state; subscript j = 1, 2, ..., m; The given value of the AC port current phase angle is θ ref , combined with θ ref ,I m,refi Get the instantaneous current given value i of multiple micro-inverters g,refi and respectively calculate the internal and external phase shift angles of the multi-channel micro-inverters through the multi-channel micro-inverter feedforward calculation module; subscript i=1,2,...,n+m; The AC port voltage control adopts the master-slave control mode, that is, only one micro-inverter is used as the master to perform voltage closed-loop control, and the other micro-inverters are used as slaves to perform only feedforward control, and the master performs gain compensation on the AC port voltage; The battery power setpoint module sets the current amplitude setpoint I of the multi-channel micro-inverter AC port according to the output of the MPPT module. m,refi , the load resistance value R calculated in real time L 、AC port voltage d-axis component given value v d,ref And the battery output current given value coefficient α j Determine the current amplitude given value I of the AC port of the i-th micro-inverter m,refk , subscript k = n+1, n+2, ..., n+m; Voltage loop module, for photovoltaic panel voltage v pvx Perform closed-loop control to make it close to the photovoltaic panel voltage reference value V output by the MPPT module pv,refx ;;Subscript x=1,2,...,n; The phase shift controller is based on the internal phase shift angle D of the multi-channel micro-inverter 1i and the outward phase angle D 2i Generate PWM control signals for each switch tube.

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