Power control method, device and system for photovoltaic and energy storage integrated grid-connected inverter

Abstract

The present invention discloses a power control method, device and system for a photovoltaic-storage integrated grid-connected inverter. The method includes inputting a three-phase grid voltage and a three-phase grid current into an AC-side power controller, and outputting a three-phase initial modulation wave signal after processing; inputting a photovoltaic voltage and a photovoltaic current into a DC-side photovoltaic power controller, and outputting a control parameter after processing; calculating an asymmetric triangular carrier based on the photovoltaic voltage and the energy storage voltage; inputting the three-phase initial modulation wave signal, the control parameter and the asymmetric triangular carrier into an asymmetric carrier pulse width modulator to generate a PWM signal for controlling the switch tube of the inverter bridge in the grid-connected inverter. The present invention uses the DC-side photovoltaic power controller to output a control parameter to correct the three-phase modulation wave output by the AC-side power controller, and the corrected modulation wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, thereby realizing the power control of the photovoltaic-storage integrated grid-connected inverter.

Description

Technical Field

[0001] The present invention belongs to the technical field of control of power electronic converters, and in particular relates to a power control method, device and system for a photovoltaic and energy storage integrated grid-connected inverter. Background Art

[0002] In recent years, with the increasing problems of resource shortage and environmental pollution, renewable energy such as solar energy and wind energy has received extensive attention. Affected by weather and environment, photovoltaic output power is volatile. In order to smooth out the fluctuation of photovoltaic power, corresponding energy storage devices are often configured in photovoltaic power generation systems to form an integrated photovoltaic storage system.

[0003] There are two main types of typical photovoltaic and energy storage integrated system structures. One is that photovoltaic and energy storage are connected to the AC grid through their own DC / AC converters, and the other is that photovoltaic and energy storage are connected to the public DC bus through DC / DC converters, and then connected to the AC grid through a centralized DC / AC converter. These traditional photovoltaic and energy storage integrated systems require multiple power electronic converters, which are costly and inefficient. Summary of the invention

[0004] In view of the above problems, the present invention proposes a power control method, device and system for a photovoltaic and energy storage integrated grid-connected inverter. The control parameters of the DC side photovoltaic power controller are used to correct the three-phase modulation wave output by the AC side power controller. The corrected modulation wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal. The asymmetric triangular carrier in the control method can adapt to the voltage changes of photovoltaics and energy storage. The power controllers on the AC and DC sides realize power control by real-time correction of the modulation wave signal.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a power control method for a photovoltaic-storage integrated grid-connected inverter, comprising:

[0007] Obtain three-phase grid voltage, three-phase grid current, photovoltaic voltage, photovoltaic current and energy storage voltage;

[0008] The three-phase grid voltage and the three-phase grid current are input to the AC side power controller, and after processing, a three-phase initial modulation wave signal is output;

[0009] The photovoltaic voltage and photovoltaic current are input into a DC-side photovoltaic power controller, and control parameters are output after processing;

[0010] An asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage;

[0011] The three-phase initial modulation wave signal, control parameters and asymmetric triangular carrier are input into an asymmetric carrier pulse width modulator to generate a PWM signal, and the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter.

[0012] Optionally, the method further comprises:

[0013] When it is determined that the three-phase grid voltage is over-voltage and / or the three-phase grid current is over-current, all PWM signals are set to low level, so that the grid-connected inverter is shut down.

[0014] Optionally, the control parameter is obtained by the following processing method:

[0015] Calculating photovoltaic power based on the photovoltaic voltage and photovoltaic current;

[0016] After the photovoltaic power is output by the MPPT algorithm, the limiting unit outputs a control parameter k, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller.

[0017] Optionally, the asymmetric carrier pulse width modulator includes a connected modulation wave correction calculation unit and a comparison unit with the asymmetric carrier.

[0018] Optionally, the modulation wave correction calculation unit performs the following steps:

[0019] Obtain the minimum and maximum values ​​of the three-phase initial modulation wave signal;

[0020] Calculate the correction amount of the modulation wave in combination with the output parameters;

[0021] The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal.

[0022] Optionally, the minimum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0023] u min =min(u a ,u b ,u c )

[0024]

[0025] The maximum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0026] u max =max(u a ,u b ,u c );

[0027] The correction amount of the modulation wave is calculated by the following formula:

[0028] u0=(u max -u min -2)·k+1-u max

[0029] The modified three-phase modulation wave signal is calculated by the following formula:

[0030]

[0031] Among them, m and θ are the modulation ratio and phase respectively, and k is the control parameter.

[0032] Optionally, the comparison unit with the asymmetric carrier performs the following steps:

[0033] The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 .

[0034] Optionally, the amplitude expression of the carrier is:

[0035]

[0036] Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

[0037] In a second aspect, the present invention provides a power control device for a photovoltaic and energy storage integrated grid-connected inverter, comprising:

[0038] An acquisition module is used to acquire three-phase grid voltage, three-phase grid current, photovoltaic voltage, photovoltaic current and energy storage voltage;

[0039] A first processing module, used for inputting the three-phase grid voltage and the three-phase grid current into the AC side power controller, and outputting a three-phase initial modulation wave signal after processing;

[0040] A second processing module is used to input the photovoltaic voltage and photovoltaic current into a DC-side photovoltaic power controller and output control parameters after processing;

[0041] A calculation module, used for calculating an asymmetric triangular carrier based on a photovoltaic voltage and an energy storage voltage;

[0042] The control module is used to input the three-phase initial modulation wave signal, control parameters and asymmetric triangular carrier into an asymmetric carrier pulse width modulator to generate a PWM signal, and the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter.

[0043] In a third aspect, the present invention provides a power control device for a photovoltaic-storage integrated grid-connected inverter, comprising: an AC-side power controller, a DC-side photovoltaic power controller, and an asymmetric carrier pulse width modulator;

[0044] The AC side power controller receives the three-phase grid voltage and the three-phase grid current, and outputs the three-phase initial modulation wave signal after processing;

[0045] The DC side photovoltaic power controller receives the photovoltaic voltage and photovoltaic current, and outputs the control parameters after processing;

[0046] The asymmetric carrier pulse width modulator generates a PWM signal based on the three-phase initial modulation wave signal and control parameters, and an asymmetric triangular carrier. The PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter. The asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage.

[0047] Optionally, the AC side power controller includes a dq conversion module, an active current loop regulator, and a dq inverse conversion module connected in sequence, and also includes a phase-locked loop, the input end of the phase-locked loop is connected to the three-phase grid voltage, and the output end is connected to the dq conversion module and the dq inverse conversion module respectively; the three-phase grid current i ga ,i gb ,i gc The dq conversion module generates a d-axis current signal i in the dq coordinate system. gd and the q-axis current signal i gq ; d-axis current reference signal i gdref and the d-axis current signal i gd Subtract, and after the active current loop regulator, the d-axis modulation signal u is output d ;q-axis current reference signal i gqref With the q-axis current signal i gq Subtract, and after passing through the reactive current loop regulator, the q-axis modulation signal u is output q ; Modulation signal u in dq coordinate system d and u q After passing through the dq inverse transformation module, a three-phase initial modulation wave signal u is generated. a ,u b ,u c .

[0048] Optionally, the DC side photovoltaic power controller includes an MPPT controller and a limiting unit connected in sequence; the MPPT controller is based on the photovoltaic voltage U PV 、Photovoltaic current I PV , calculate the photovoltaic power, and use the MPPT algorithm to process the photovoltaic power, and then output the control parameter k through the limiting unit, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller to achieve power regulation.

[0049] Optionally, the asymmetric carrier pulse width modulator includes a modulation wave correction calculation unit and a comparison unit with the asymmetric carrier connected thereto; the modulation wave correction calculation unit performs the following steps:

[0050] Obtain the minimum and maximum values ​​of the three-phase initial modulation wave signal;

[0051] Calculate the correction amount of the modulation wave in combination with the output parameters;

[0052] The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal;

[0053] The comparison unit with the asymmetric carrier performs the following steps:

[0054] The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 .

[0055] Optionally, the minimum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0056] u min =min(u a ,u b ,u c )

[0057]

[0058] The maximum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0059] u max =max(u a ,u b ,u c );

[0060] The correction amount of the modulation wave is calculated by the following formula:

[0061] u0=(umax -u min -2)·k+1-u max

[0062] The modified three-phase modulation wave signal is calculated by the following formula:

[0063]

[0064] Among them, m and θ are the modulation ratio and phase respectively, and k is the control parameter.

[0065] Optionally, the amplitude expression of the carrier is:

[0066]

[0067] Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

[0068] In a fourth aspect, the present invention provides a power control system for a photovoltaic-storage integrated grid-connected inverter, comprising a storage medium and a processor;

[0069] The storage medium is used to store instructions;

[0070] The processor is configured to operate according to the instructions to execute the steps of the method according to any one of the first aspects.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] The present invention uses the control parameters of the DC side photovoltaic power controller output to correct the three-phase modulation wave output by the AC side power controller. The corrected modulation wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal. The asymmetric triangular carrier in the control method can adapt to the voltage changes of photovoltaics and energy storage. The power controller on the AC and DC sides realizes power control by real-time correction of the modulation wave signal.

[0073] The present invention can realize smooth power regulation among photovoltaic, energy storage and AC power grid, and the control algorithm is simple and easy to realize. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein:

[0075] Figure 1 This is a typical photovoltaic and energy storage integrated grid-connected inverter topology diagram;

[0076] Figure 2 A flow chart of a control method provided in one embodiment of the present invention;

[0077] Figure 3 A schematic diagram of a control device provided in one embodiment of the present invention;

[0078] Figure 4 The figure is a simulation waveform of a control method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0080] The application principle of the present invention is described in detail below in conjunction with the accompanying drawings.

[0081] Since the photovoltaic and energy storage integrated grid-connected inverter uses an integrated DC / AC converter to simultaneously connect photovoltaic, energy storage and AC power grid, it has the advantages of simple structure, high integration and high efficiency. The photovoltaic and energy storage integrated grid-connected inverter based on the three-level structure is a typical circuit topology, such as Figure 1 As shown. Its DC side is connected to photovoltaic and energy storage, and its AC side is connected to the AC grid. The photovoltaic and energy storage voltages are respectively denoted as U PV and U ESS , the AC grid voltage is recorded as u ga ,u gb ,u gc The main power circuit of the inverter consists of 12 switches (S a1 ~S a4 , S b1 ~S b4 , S c1 ~S c4 ), 6 diodes (D a1 ~D a2 , D b1 ~D b2 , D c1 ~D c2 ) and 3 filter inductors (L a , L b , L c ).

[0082] Example 1

[0083] The present invention provides a method for controlling power of a photovoltaic-storage integrated grid-connected inverter. Figure 2 As shown, the specific steps include:

[0084] Collect three-phase grid voltage u ga ,u gb ,u gc , three-phase grid current iga ,i gb ,i gc , Photovoltaic voltage U PV 、Photovoltaic current I PV and energy storage voltage U ESS ;

[0085] The three-phase grid voltage u ga ,u gb ,u gc and the three-phase grid current i ga ,i gb ,i gc Input to the AC side power controller, the AC side power control is realized through the active and reactive current loops under the dq axis, and then outputs the three-phase initial modulation wave signal u a ,u b ,u c ;

[0086] The photovoltaic voltage U PV 、Photovoltaic current I PV The input is sent to the photovoltaic power controller on the DC side, and after processing, the control parameter k is output, where the range of k is 0≤k≤1;

[0087] An asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage;

[0088] The three-phase initial modulation wave signal u a ,u b ,u c , control parameter k and asymmetric triangular carrier are input to an asymmetric carrier pulse width modulator to generate a PWM signal, and the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter;

[0089] When it is determined that the three-phase grid voltage is overvoltage and / or the three-phase grid current is overcurrent, all PWM signals are set to low level, so that the grid-connected inverter is shut down, otherwise wait for the next cycle signal to return to the initial step and start execution.

[0090] In a specific implementation of the embodiment of the present invention, the control parameter is obtained by the following processing method:

[0091] Based on the photovoltaic voltage U PV 、Photovoltaic current I PV , calculate the photovoltaic power;

[0092] After the photovoltaic power is output by the MPPT algorithm, the limiting unit outputs a control parameter k, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller.

[0093] In a specific implementation of the embodiment of the present invention, the asymmetric carrier pulse width modulator includes a modulation wave correction calculation unit and a comparison unit with an asymmetric carrier connected to each other.

[0094] Wherein, the modulation wave correction calculation unit performs the following steps:

[0095] The minimum and maximum values ​​of the three-phase initial modulation wave signal are obtained; the minimum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0096] u min =min(u a ,u b ,u c )

[0097]

[0098] The maximum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0099] u max =max(u a ,u b ,u c );

[0100] Combined with the output parameters, the correction amount of the modulated wave is calculated; the correction amount of the modulated wave is calculated by the following formula:

[0101] u0=(u max -u min -2)·k+1-u max

[0102] The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal; the corrected three-phase modulation wave signal is calculated by the following formula:

[0103]

[0104] Among them, m and θ are the modulation ratio and phase respectively, and k is the control parameter.

[0105] In a specific implementation of the embodiment of the present invention, the comparison unit with the asymmetric carrier performs the following steps:

[0106] The modified three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase, but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 .

[0107] Wherein, the amplitude expression of the carrier is:

[0108]

[0109] Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

[0110] In order to verify the effectiveness of the power control method of the present invention, the present invention provides a specific example, and its main parameters are as follows:

[0111] Photovoltaic voltage U PV =800V;

[0112] Energy storage voltage U ESS =360V;

[0113] AC grid line voltage effective value U AC(RMS) =380V;

[0114] AC side rated power P AC =30kW;

[0115] Switching frequency f s =10kHz;

[0116] Filter inductor L a =L b =L c =3mH;

[0117] use Figure 2 The simulation waveform of the control method provided by the present invention is shown as follows Figure 4 As shown in the figure, when the rated power of the AC side is 30kW and the photovoltaic MPPT power is 17kW, the energy storage provides the remaining required power of 13kW, realizing the power regulation between photovoltaic, energy storage and AC power grid, verifying the effectiveness of the control method of the present invention.

[0118] Example 2

[0119] Based on the same inventive concept as that of Example 1, an embodiment of the present invention provides a power control device applicable to a photovoltaic-storage integrated grid-connected inverter, comprising:

[0120] An acquisition module is used to acquire three-phase grid voltage, three-phase grid current, photovoltaic voltage and photovoltaic current;

[0121] A first processing module, used for inputting the three-phase grid voltage and the three-phase grid current into the AC side power controller, and outputting a three-phase initial modulation wave signal after processing;

[0122] A second processing module is used to input the photovoltaic voltage and photovoltaic current into a DC-side photovoltaic power controller and output control parameters after processing;

[0123] A calculation module, used for calculating an asymmetric triangular carrier based on a photovoltaic voltage and an energy storage voltage;

[0124] The control module is used to input the three-phase initial modulation wave signal, control parameters and asymmetric triangular carrier into an asymmetric carrier pulse width modulator to generate a PWM signal, and the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter.

[0125] Example 3

[0126] Based on the same inventive concept as in Example 1, Figure 3 As shown, an embodiment of the present invention provides a power control device suitable for a photovoltaic storage integrated grid-connected inverter, including: an AC side power controller, a DC side photovoltaic power controller and an asymmetric carrier pulse width modulator;

[0127] The AC side power controller receives the three-phase grid voltage u ga ,u gb ,u gc and the three-phase grid current i ga ,i gb ,i gc After processing, the three-phase initial modulation wave signal u is output a ,u b ,u c ;

[0128] The DC side photovoltaic power controller receives the photovoltaic voltage U PV and photovoltaic current I PV , after processing, the control parameter k is output;

[0129] The asymmetric carrier pulse width modulator is based on the received three-phase initial modulation wave signal u a ,u b ,u c , control parameter k,, and an asymmetric triangular carrier to generate a PWM signal, wherein the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter; the asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage.

[0130] In a specific implementation of the embodiment of the present invention, the AC side power controller includes a dq conversion module, an active current loop regulator, and a dq inverse conversion module connected in sequence, and also includes a phase-locked loop, the input end of the phase-locked loop is connected to the three-phase grid voltage, and the output end is connected to the dq conversion module and the dq inverse conversion module respectively. ga ,i gb ,igc The dq conversion module generates a d-axis current signal i in the dq coordinate system. gd and the q-axis current signal i gq . d-axis current reference signal i gdref and the d-axis current signal i gd Subtract, and after the active current loop regulator, the d-axis modulation signal u is output d ;q-axis current reference signal i gqref With the q-axis current signal i gq Subtract, and after passing through the reactive current loop regulator, the q-axis modulation signal u is output q The modulation signal u in the dq coordinate system d and u q After passing through the dq inverse transformation module, a three-phase initial modulation wave signal u is generated. a ,u b ,u c .

[0131] In a specific implementation of the embodiment of the present invention, the DC side photovoltaic power controller includes an MPPT controller and a limiter unit connected in sequence; the MPPT controller is based on the photovoltaic voltage U PV 、Photovoltaic current I PV , calculate the photovoltaic power, and use the MPPT algorithm to process the photovoltaic power, and then output the control parameter k through the limiting unit, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller to achieve power regulation.

[0132] In a specific implementation of the embodiment of the present invention, the asymmetric carrier pulse width modulator includes a modulation wave correction calculation unit and a comparison unit with an asymmetric carrier connected to each other.

[0133] Wherein, the modulation wave correction calculation unit performs the following steps:

[0134] The minimum and maximum values ​​of the three-phase initial modulation wave signal are obtained; the minimum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0135] u min =min(u a ,u b ,u c )

[0136]

[0137] The maximum value of the three-phase initial modulation wave signal is calculated by the following formula:

[0138] u max =max(u a ,ub ,u c );

[0139] Combined with the output parameters, the correction amount of the modulated wave is calculated; the correction amount of the modulated wave is calculated by the following formula:

[0140] u0=(u max -u min -2)·k+1-u max

[0141] The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal; the corrected three-phase modulation wave signal is calculated by the following formula:

[0142]

[0143] Among them, m and θ are the modulation ratio and phase respectively, and k is the control parameter.

[0144] In a specific implementation of the embodiment of the present invention, the comparison unit with the asymmetric carrier performs the following steps:

[0145] The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, wherein the asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage. The triangular carrier has the same frequency and phase, but different amplitudes, and is stacked in the interval of the vertical coordinate from -1 to 1. From top to bottom, it is the first and second carriers, recorded as u tri1 、u tri2 .

[0146] Wherein, the amplitude expression of the carrier is:

[0147]

[0148] Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

[0149] Example 4

[0150] An embodiment of the present invention provides a power control system applicable to a photovoltaic-storage integrated grid-connected inverter, including a storage medium and a processor;

[0151] The storage medium is used to store instructions;

[0152] The processor is used to operate according to the instructions to execute the steps of the method according to any one of Embodiment 1.

[0153] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A power control method for a photovoltaic and energy storage integrated grid-connected inverter, characterized in that: include: Obtain three-phase grid voltage, three-phase grid current, photovoltaic voltage, photovoltaic current and energy storage voltage; The three-phase grid voltage and the three-phase grid current are input to the AC side power controller, and after processing, a three-phase initial modulation wave signal is output; The photovoltaic voltage and photovoltaic current are input into a DC-side photovoltaic power controller, and control parameters are output after processing; An asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage; Inputting the three-phase initial modulation wave signal, control parameters and asymmetric triangular carrier into an asymmetric carrier pulse width modulator to generate a PWM signal, wherein the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter; The asymmetric carrier pulse width modulator comprises a connected modulation wave correction calculation unit and a comparison unit with the asymmetric carrier; The modulation wave correction calculation unit performs the following steps: Obtain the minimum and maximum values ​​of the three-phase initial modulation wave signal; Calculate the correction amount of the modulation wave in combination with the output control parameter; The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal; The minimum value of the three-phase initial modulation wave signal is calculated by the following formula: u min =min(u a ,u b ,u c ) The maximum value of the three-phase initial modulation wave signal is calculated by the following formula: u max =max(u a ,u b ,u c ); The correction amount of the modulation wave is calculated by the following formula: u0=(u max -u min -2)·k+1-u max The modified three-phase modulation wave signal is calculated by the following formula: Among them, m and θ are modulation ratio and phase respectively, and k is the control parameter; The comparison unit with the asymmetric carrier performs the following steps: The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 ; The amplitude expression of the carrier is: Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

2. The power control method of a photovoltaic-storage integrated grid-connected inverter according to claim 1, characterized in that: The method further comprises: When it is determined that the three-phase grid voltage is over-voltage and / or the three-phase grid current is over-current, all PWM signals are set to low level, so that the grid-connected inverter is shut down.

3. The power control method of a photovoltaic-storage integrated grid-connected inverter according to claim 1, characterized in that: The control parameters are obtained by the following processing method: Calculating photovoltaic power based on the photovoltaic voltage and photovoltaic current; After the photovoltaic power is output by the MPPT algorithm, the limiting unit outputs a control parameter k, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller.

4. A power control device for a photovoltaic and energy storage integrated grid-connected inverter, characterized in that: include: An acquisition module is used to acquire three-phase grid voltage, three-phase grid current, photovoltaic voltage, photovoltaic current and energy storage voltage; A first processing module, used for inputting the three-phase grid voltage and the three-phase grid current into the AC side power controller, and outputting a three-phase initial modulation wave signal after processing; A second processing module is used to input the photovoltaic voltage and photovoltaic current into a DC-side photovoltaic power controller and output control parameters after processing; A calculation module, used for calculating an asymmetric triangular carrier based on a photovoltaic voltage and an energy storage voltage; A control module, used for inputting the three-phase initial modulation wave signal, control parameters and asymmetric triangular carrier into an asymmetric carrier pulse width modulator to generate a PWM signal, wherein the PWM signal is used for controlling the switch tube of the inverter bridge in the grid-connected inverter; The asymmetric carrier pulse width modulator comprises a connected modulation wave correction calculation unit and a comparison unit with the asymmetric carrier; The modulation wave correction calculation unit performs the following steps: Obtain the minimum and maximum values ​​of the three-phase initial modulation wave signal; Calculate the correction amount of the modulation wave in combination with the output control parameter; The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal; The minimum value of the three-phase initial modulation wave signal is calculated by the following formula: u min =min(u a ,u b ,u c ) The maximum value of the three-phase initial modulation wave signal is calculated by the following formula: u max =max(u a ,u b ,u c ); The correction amount of the modulation wave is calculated by the following formula: u0=(u max -u min -2)·k+1-u max The modified three-phase modulation wave signal is calculated by the following formula: Among them, m and θ are modulation ratio and phase respectively, and k is the control parameter; The comparison unit with the asymmetric carrier performs the following steps: The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 ; The amplitude expression of the carrier is: Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

5. A power control device for a photovoltaic and energy storage integrated grid-connected inverter, comprising: AC side power controller, DC side photovoltaic power controller and asymmetric carrier pulse width modulator; The AC side power controller receives the three-phase grid voltage and the three-phase grid current, and outputs the three-phase initial modulation wave signal after processing; The DC side photovoltaic power controller receives the photovoltaic voltage and photovoltaic current, and outputs the control parameters after processing; The asymmetric carrier pulse width modulator generates a PWM signal based on the three-phase initial modulation wave signal and control parameters, and an asymmetric triangular carrier, wherein the PWM signal is used to control the switch tube of the inverter bridge in the grid-connected inverter, and the asymmetric triangular carrier is calculated based on the photovoltaic voltage and the energy storage voltage; The asymmetric carrier pulse width modulator comprises a connected modulation wave correction calculation unit and a comparison unit with the asymmetric carrier; The modulation wave correction calculation unit performs the following steps: Obtain the minimum and maximum values ​​of the three-phase initial modulation wave signal; Calculate the correction amount of the modulation wave in combination with the output control parameter; The correction amount is added to the three-phase initial modulation wave signal to calculate the corrected three-phase modulation wave signal; The minimum value of the three-phase initial modulation wave signal is calculated by the following formula: u min =min(u a ,u b ,u c ) The maximum value of the three-phase initial modulation wave signal is calculated by the following formula: u max =max(u a ,u b ,u c ); The correction amount of the modulation wave is calculated by the following formula: u0=(u max -u min -2)·k+1-u max The modified three-phase modulation wave signal is calculated by the following formula: Among them, m and θ are modulation ratio and phase respectively, and k is the control parameter; The comparison unit with the asymmetric carrier performs the following steps: The corrected three-phase modulated wave signal is compared with the asymmetric triangular carrier to generate a PWM drive signal, in which the triangular carrier has the same frequency and phase but different amplitudes, and is stacked in the interval from -1 to 1 on the vertical axis. From top to bottom, they are the first and second carriers, denoted as u tri1 、u tri2 ; The amplitude expression of the carrier is: Among them: U PV is the photovoltaic voltage, U ESS is the energy storage voltage.

6. The power control device of the photovoltaic and energy storage integrated grid-connected inverter according to claim 5, characterized in that: The AC side power controller includes a dq conversion module, an active current loop regulator, and a dq inverse conversion module connected in sequence, and also includes a phase-locked loop, the input end of the phase-locked loop is connected to the three-phase grid voltage, and the output end is connected to the dq conversion module and the dq inverse conversion module respectively; the three-phase grid current i ga ,i gb ,i gc The dq conversion module generates a d-axis current signal i in the dq coordinate system. gd and the q-axis current signal i gq ; d-axis current reference signal i gdref and the d-axis current signal i gd Subtract, and after the active current loop regulator, the d-axis modulation signal u is output d ;q-axis current reference signal i gqref With the q-axis current signal i gq Subtract, and after passing through the reactive current loop regulator, the q-axis modulation signal u is output q ; Modulation signal u in dq coordinate system d and u q After passing through the dq inverse transformation module, a three-phase initial modulation wave signal u is generated. a ,u b ,u c .

7. The power control device of a photovoltaic-storage integrated grid-connected inverter according to claim 5, characterized in that: The DC side photovoltaic power controller includes an MPPT controller and a limiting unit connected in sequence; the MPPT controller is based on the photovoltaic voltage U PV 、Photovoltaic current I PV , calculate the photovoltaic power, and use the MPPT algorithm to process the photovoltaic power, and then output the control parameter k through the limiting unit, where the range of k is 0≤k≤1. The control parameter is used to correct the initial modulation wave output by the AC side power controller to achieve power regulation.

8. A power control system for a photovoltaic and energy storage integrated grid-connected inverter, characterized in that: including storage media and processors; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 4.

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