Inductive current feedforward and coupling enhancement-based grid-connected stability improvement method for grid-forming type inverter

Abstract

The invention relates to a method for improving the grid-connected stability of a grid-forming type inverter based on inductive current feedforward and coupling enhancement, and belongs to the technical field of inverter control. The method comprises the following steps: measuring inverter port voltage and filter inductive current, and calculating output active power and reactive power; calculating a port voltage reference value according to the amplitude and phase angle reference of the port voltage generated by the active controller and the reactive controller respectively; and taking the port voltage as a feedback value of the voltage regulator, and subtracting the feedback value from the port voltage reference value to serve as the input of the voltage regulator. And then adding the feedforward inductive current to the output of the voltage regulator to obtain a current reference value, and subtracting the inductive current from the current reference value to serve as the input of the current regulator. And finally, the output of the current regulator is added with the feedforward port voltage and combined with the cross-coupling enhanced voltage to obtain a modulation signal, and the modulation signal is subjected to space vector modulation to generate a driving signal so as to control the inverter. According to the method, on the premise that hardware cost and software complexity are not increased, the stable operation capacity of the grid-forming inverter under the strong power grid working condition is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter control, and in particular to a method for improving the grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement. Background Art

[0002] Currently, there are two main types of grid-connected inverters: grid-following and grid-forming. Grid-following inverters follow the grid voltage phase and control the grid current, offering advantages such as fast power regulation and high renewable energy utilization. However, they generally operate primarily to maximize active power output and cannot maintain grid voltage and frequency stability like traditional synchronous generators. With the increasing penetration of renewable energy generation, the grid is gradually shifting from a strong grid to a weak grid. To enhance the adaptability of grid-connected inverters in complex operating conditions, grid-forming inverters have emerged.

[0003] Grid-type inverters have the potential to simulate the damping and inertia of traditional synchronous generators. While they can provide frequency and voltage support for the grid, they generally use a dual-inner-loop control structure for voltage and current, which poses an oscillation risk in strong grid conditions. Existing oscillation suppression methods primarily rely on virtual impedance methods. However, this method has limited effectiveness in reshaping the inverter's impedance and relies on differential operations, which can introduce high-frequency noise. Therefore, a low-pass filter is required. Improper low-pass filter design can lead to new stability issues for grid-type inverters during standalone operation, making the design of control parameters more difficult.

[0004] Therefore, those skilled in the art are eager to improve the grid-connected stability of the grid-connected inverter without increasing the hardware cost and software complexity. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement, characterized by comprising:

[0008] Step S1: Collect the inverter port voltage v a 、v b 、v c and the filter inductor current i a 、i b 、i c And the d-axis sampling port voltage v is obtained by abc / dq coordinate transformation d, q-axis sampling port voltage v q and d-axis sampling filter inductor current i d , q-axis sampling filter inductor current i q ;

[0009] Step S2: By v d 、v q 、i d 、i q Calculate the inverter output active power and reactive power;

[0010] Step S3: Calculate the phase and amplitude of the port voltage reference according to the active power and reactive power and their reference values, and further obtain the d-axis voltage reference value v dref and q-axis voltage reference value v qref ;

[0011] Step S4: subtracting the dq axis port voltage reference value from the dq axis sampling port voltage, and further calculating the dq axis current error, and adding the dq axis current error to the dq axis feedforward inductor current to obtain the dq axis inductor current reference value;

[0012] Step S5: The difference between the d-axis and q-axis inductor current reference values and the d-axis and q-axis sampled inductor currents is used as the input of the d-axis and q-axis current regulators. The d-axis current regulator output is added with the d-axis feedforward port voltage and subtracted with the d-axis coupling voltage to obtain a d-axis modulated wave. The q-axis current regulator output is added with the q-axis feedforward port voltage and added with the q-axis coupling voltage to obtain a q-axis modulated wave. The q-axis coupling voltage is the product of the d-axis inductor current and the coupling enhancement coefficient, and the d-axis coupling voltage is the product of the q-axis inductor current and the coupling enhancement coefficient.

[0013] Step S6: The dq axis modulation wave is transformed into the abc coordinate system modulation wave through dq / abc coordinate transformation, and a driving signal is generated through space vector modulation.

[0014] In step S1, the abc / dq coordinate system is transformed from a three-phase stationary coordinate system to a two-phase rotating coordinate system.

[0015] The transformation formula for converting the three-phase stationary reference system voltage to the two-phase rotating reference system voltage is:

[0016]

[0017] Where: θ is the phase of the port voltage reference;

[0018] The transformation formula for converting the three-phase stationary coordinate system current to the two-phase rotating coordinate system current is:

[0019]

[0020] The inverter outputs active power and reactive power respectively:

[0021] p=1.5×(v d i d +v q i q )

[0022] q=1.5×(v q i d -v d i q )

[0023] Where: p is the active power output by the inverter, and is the reactive power output by the inverter.

[0024] The step S3 comprises:

[0025] Step S3-1: Calculate the phase of the port voltage reference based on the inverter output active power and its reference value:

[0026]

[0027] Where: θ is the phase of the port voltage reference, P ref is the inverter output active power reference value, ω n is the rated angular frequency of the three-phase power grid, D p is the active damping coefficient, J is the virtual moment of inertia, and s is the Laplace operator;

[0028] Step S3-2: Calculate the amplitude of the port voltage reference based on the inverter output, reactive power, and reference value:

[0029]

[0030] Where: E m is the amplitude of the port voltage reference value, Q ref is the inverter output reactive power reference value, V n is the rated voltage amplitude of the three-phase power grid, v amp is the amplitude of the port voltage, D q is the reactive damping coefficient, K is the reactive inertia coefficient;

[0031] Step S3-3: Calculate the port voltage reference value based on the phase and amplitude of the port voltage reference:

[0032]

[0033] Where: v ref is the port voltage reference value.

[0034] The step S4 comprises:

[0035] Step S4-1: dq axis port voltage reference v dref and v qref Respectively with the dq axis port voltage v d and v q The difference is used as the input of the voltage regulator to obtain the dq axis current error:

[0036] Δi d =H v (s)(v dref -v d )

[0037] Δi q =H v (s)(v qref -v q )

[0038] Where: Δi d is the d-axis current error, Δi q is the q-axis current error, H v (s) is the transfer function of the voltage regulator

[0039] Step S4-2: Add the dq axis current error to the dq axis feedforward inductor current to obtain a dq axis inductor current reference value:

[0040] i dref =Δi d +i d

[0041] i qref =Δi q +i q

[0042] Where: i dref is the d-axis inductor current reference value, i qref is the q-axis inductor current reference value.

[0043] The step S5 comprises:

[0044] Step S5-1: Subtract the dq axis inductor current reference value from the dq axis sampled inductor current and obtain the following through the current regulator:

[0045] Δv d1 =H i (s)(i dref -i d )

[0046] Δv q1 =H i (s)(i qref -i q )

[0047] Where: Δv d1is the first error current of the d-axis, Δv q1 is the first error current of q axis, H i (s) is the transfer function of the current regulator;

[0048] Step S5-2: d-axis inductor current i d Multiply by the coupling enhancement coefficient -ωL dec Get the q-axis coupling voltage Δv d2 , q-axis inductor current i q Multiply by the coupling enhancement coefficient -ωL dec Get the d-axis coupling voltage Δv q2 ;

[0049] Step S5-3: d-axis first error current Δv d1 Add the d-axis feedforward port voltage v d And subtract the d-axis coupling voltage Δv d2 Get the d-axis modulation wave m d ; q-axis first error current Δv q1 Add the q-axis feedforward port voltage v q And add the d-axis coupling voltage Δv q2 Get the q-axis modulation wave m q :

[0050] m d =Δv d1 -Δv d2 +v d

[0051] m q =Δv q1 +Δv q2 +v q

[0052] Δv d2 =-i q ω n L dec

[0053] Δv q2 =-i d ω n L dec

[0054] Where: L dec Increase inductance for coupling.

[0055] The step S6 comprises:

[0056] Step S6-1: The obtained dq axis modulated wave is transformed into a three-phase stationary coordinate system through dq / abc coordinate transformation to obtain the abc coordinate system modulated wave:

[0057]

[0058] Step S6-2: The abc coordinate system modulated wave is sent to the PWM module to generate a drive signal to control the inverter; the modulated wave is compared with the three-phase triangular carrier and a drive signal is generated through the space vector modulation method.

[0059] The grid-type inverter includes: a DC side power supply, a three-phase inverter, a three-phase grid impedance and a three-phase grid.

[0060] A device for improving the grid-connected stability of a grid-connected inverter based on inductive current feedforward and coupling enhancement includes a memory, a processor, and a program stored in the memory. When the processor executes the program, the method described above is implemented.

[0061] A storage medium stores a program, which implements the above method when executed.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1. The method of the present invention reshapes the impedance characteristics of the grid-type inverter by combining inductor current feedforward and coupling enhancement control. Compared with the current voltage-current dual closed-loop control grid-type inverter, it can avoid current oscillation under strong grid conditions and achieve stable operation under strong grid conditions.

[0064] 2. Compared with reshaping the impedance characteristics of the inverter through the virtual impedance method, the method of the present invention can avoid introducing differential control to cause new oscillation problems when the inverter is running independently.

[0065] 3. Compared with reshaping the impedance characteristics of the inverter through the virtual impedance method, the method of the present invention can avoid the additional design of a low-pass filter and reduce the difficulty of designing the control parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 A circuit topology diagram of a three-phase grid-connected inverter according to an embodiment of the present invention;

[0067] Figure 2 A schematic diagram of a control link of a grid-type inverter according to an embodiment of the present invention;

[0068] Figure 3 A schematic diagram of a grid-type inverter power controller according to an embodiment of the present invention;

[0069] Figure 4 The waveform diagram of the inverter output voltage and current before the method of the present invention is adopted;

[0070] Figure 5 The figure shows the output voltage and current waveforms of the inverter after adopting the method of the present invention. DETAILED DESCRIPTION

[0071] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0072] In some embodiments of the present invention, a method for improving the grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement is disclosed. The converter topology to which the control method is applied includes: a DC side power supply, a three-phase converter, a three-phase grid impedance, and a three-phase grid; wherein the three-phase converter includes a three-phase full-bridge circuit, a three-phase LC filter, a three-phase voltage sensor, a three-phase current sensor, and a three-phase inverter controller;

[0073] In a three-phase converter: a three-phase full-bridge circuit is connected to a three-phase LC filter. A three-phase voltage sensor and a three-phase current sensor respectively sample the three-phase voltage at the inverter port and the three-phase current at the filter inductor, and transmit the sampled signals to a three-phase converter controller. After calculation, the three-phase converter controller outputs a drive signal to control the three-phase converter circuit.

[0074] A method for improving grid-connected stability of grid-connected inverters based on inductor current feedforward and coupling enhancement, such as Figure 2 Shown, including:

[0075] Step S1: Collect the inverter port voltage v a 、v b 、v c and the filter inductor current i a 、i b 、i c And the d-axis sampling port voltage v is obtained by abc / dq coordinate transformation d , q-axis sampling port voltage v q and d-axis sampling filter inductor current i d , q-axis sampling filter inductor current i q ;

[0076] Among them, the abc / dq coordinate transformation is the transformation from the three-phase stationary coordinate system to the two-phase rotating coordinate system.

[0077] The transformation formula for converting the three-phase stationary reference system voltage to the two-phase rotating reference system voltage is:

[0078]

[0079] Where: θ is the phase of the port voltage reference;

[0080] The transformation formula for converting the three-phase stationary coordinate system current to the two-phase rotating coordinate system current is:

[0081]

[0082] Step S2: By v d 、v q 、i d 、i q Calculate the inverter output active power and reactive power;

[0083] In this embodiment, the inverter outputs active power and reactive power respectively:

[0084] p=1.5×(v d i d +v q i q )

[0085] q=1.5×(v q i d -v d i q )

[0086] Where: p is the active power output by the inverter, and is the reactive power output by the inverter.

[0087] Step S3: Calculate the phase and amplitude of the port voltage reference according to the active power and reactive power and their reference values, and further obtain the d-axis voltage reference value v dref and q-axis voltage reference value v qref ,include:

[0088] Step S3-1: Calculate the phase of the port voltage reference based on the inverter output active power and its reference value:

[0089]

[0090] Where: θ is the phase of the port voltage reference, P ref is the inverter output active power reference value, ω n is the rated angular frequency of the three-phase power grid, D p is the active damping coefficient, J is the virtual moment of inertia, and s is the Laplace operator;

[0091] Step S3-2: Calculate the amplitude of the port voltage reference based on the inverter output, reactive power, and reference value:

[0092]

[0093] Where: E m is the amplitude of the port voltage reference value, Q ref is the inverter output reactive power reference value, V n is the rated voltage amplitude of the three-phase power grid, v amp is the amplitude of the port voltage, Dq is the reactive damping coefficient, K is the reactive inertia coefficient;

[0094] Step S3-3: Calculate the port voltage reference value based on the phase and amplitude of the port voltage reference:

[0095]

[0096] Where: v ref is the port voltage reference value.

[0097] Step S4: Subtracting the dq axis port voltage reference value from the dq axis sampling port voltage, and further calculating the dq axis current error, and adding the dq axis current error to the dq axis feedforward inductor current to obtain the dq axis inductor current reference value, specifically including:

[0098] Step S4-1: dq axis port voltage reference v dref and v qref Respectively with the dq axis port voltage v d and v q The difference is used as the input of the voltage regulator to obtain the dq axis current error:

[0099] Δi d =H v (s)(v dref -v d )

[0100] Δi q =H v (s)(v qref -v q )

[0101] Where: Δi d is the d-axis current error, Δi q is the q-axis current error, H v (s) is the transfer function of the voltage regulator

[0102] Step S4-2: Add the dq axis current error to the dq axis feedforward inductor current to obtain a dq axis inductor current reference value:

[0103] i dref =Δi d +i d

[0104] i qref =Δi q +i q

[0105] Where: i dref is the d-axis inductor current reference value, i qref is the q-axis inductor current reference value.

[0106] Step S5: The difference between the d-axis and q-axis inductor current reference values and the d-axis and q-axis sampled inductor currents is used as the input of the d-axis and q-axis current regulator. The d-axis current regulator output is added to the d-axis feedforward port voltage and subtracted from the d-axis coupling voltage to obtain a d-axis modulated wave. The q-axis current regulator output is added to the q-axis feedforward port voltage and added to the q-axis coupling voltage to obtain a q-axis modulated wave. The q-axis coupling voltage is the product of the d-axis inductor current and the coupling enhancement coefficient, and the d-axis coupling voltage is the product of the q-axis inductor current and the coupling enhancement coefficient. Specifically, the following steps are performed:

[0107] Step S5-1: Subtract the dq axis inductor current reference value from the dq axis sampled inductor current and obtain the following through the current regulator:

[0108] Δv d1 =H i (s)(i dref -i d )

[0109] Δv q1 =H i (s)(i qref -i q )

[0110] Where: Δv d1 is the first error current of the d-axis, Δv q1 is the first error current of q axis, H i (s) is the transfer function of the current regulator;

[0111] Step S5-2: d-axis inductor current i d Multiply by the coupling enhancement coefficient -ωL dec Get the q-axis coupling voltage Δv d2 , q-axis inductor current i q Multiply by the coupling enhancement coefficient -ωL dec Get the d-axis coupling voltage Δv q2 ;

[0112] Step S5-3: d-axis first error current Δv d1 Add the d-axis feedforward port voltage v d And subtract the d-axis coupling voltage Δv d2 Get the d-axis modulation wave m d ; q-axis first error current Δv q1 Add the q-axis feedforward port voltage v q And add the d-axis coupling voltage Δv q2 Get the q-axis modulation wave m q :

[0113] m d =Δv d1 -Δv d2 +vd

[0114] m q =Δv q1 +Δv q2 +v q

[0115] Δv d2 =-i q ω n L dec

[0116] Δv q2 =-i d ω n L dec

[0117] Where: L dec Increase inductance for coupling.

[0118] Step S6: The dq axis modulation wave is transformed into the abc coordinate system modulation wave by dq / abc coordinate transformation, and the driving signal is generated by space vector modulation, which specifically includes:

[0119] Step S6-1: The obtained dq axis modulated wave is transformed into a three-phase stationary coordinate system through dq / abc coordinate transformation to obtain the abc coordinate system modulated wave:

[0120]

[0121] Step S6-2: The abc coordinate system modulated wave is sent to the PWM module to generate a drive signal to control the inverter; the modulated wave is compared with the three-phase triangular carrier and a drive signal is generated through the space vector modulation method.

[0122] The following further discloses embodiments of the above-mentioned methods in specific application scenarios. Specifically, the main circuit and inverter control method of a typical grid-connected system is as follows: Figure 1 As shown in Figure 1. The DC side of the main circuit can be regarded as a DC source with a constant voltage. The DC-AC conversion part is realized by a three-phase full-bridge inverter circuit. The current output by the bridge arm is connected to the grid after LC filtering. The sampling part obtains the inverter port voltage and filter inductor current through the sampling device. The inverter control part is shown in Figure 1. Figure 2As shown, the inverter port voltage and filter inductor current undergo an abc / dq coordinate transformation and are input into the power calculation module to obtain the inverter's instantaneous output active power and reactive power. The inverter's instantaneous output active power is then input into the active power control module to obtain the terminal voltage reference phase, and the inverter's instantaneous output reactive power is then input into the reactive power control module to obtain the terminal voltage reference amplitude. The voltage controller's reference value is calculated based on the terminal voltage reference phase and amplitude, and then undergoes an abc / dq coordinate transformation to obtain the dq-axis voltage reference. The difference between the dq-axis voltage reference and the dq-axis sampled voltage serves as the input to the dq-axis voltage regulator, which outputs the dq-axis current error. The dq-axis current error is added to the dq-axis feedforward inductor current to obtain the dq-axis current reference. The difference between the dq-axis current reference and the dq-axis sampled current serves as the input to the dq-axis current regulator. The d-axis inductor current is multiplied by the coupling enhancement coefficient to obtain the q-axis coupled voltage, which in turn is multiplied by the coupling enhancement coefficient to obtain the d-axis coupled voltage. The d-axis modulated wave is generated by adding the d-axis feedforward port voltage to the d-axis current regulator output and subtracting the d-axis coupling voltage. The q-axis modulated wave is generated by adding the q-axis feedforward port voltage to the q-axis current regulator output and adding the q-axis coupling voltage. Finally, the modulated wave undergoes dq / abc coordinate transformation and then undergoes space vector PWM (SVPWM) to generate the drive signal for the three-phase full-bridge circuit. Figure 3 FIG. 4 is a schematic diagram of a power controller according to an embodiment of the present invention.

[0123] The main parameter values of this embodiment are as follows: main circuit parameters, DC side voltage V dc =350V, inverter side filter inductor L f =2mH, filter inductor branch resistance R f =0.2Ω, filter capacitor C f =5uF, damping resistor R d =5Ω, AC bus line voltage effective value v rms 110V, AC bus voltage frequency f0 = 50Hz, line resistance is R g =0.4Ω, line inductance is L g =6mH, inverter rated power P N =2kW, inverter switching frequency is 10kHz. Controller parameters, active power given P ref =2kW, reactive power given by Q ref =0kVar, virtual moment of inertia J = 0.0012, reactive inertia coefficient K = 2.0442, active damping coefficient D p =1.0132, reactive damping coefficient D q =128.5649, voltage controller proportional coefficient K pv =0.6, voltage controller integral coefficient K iv =10, current controller proportional coefficient K pi=2, current controller integral coefficient K ii =0, coupling enhancement inductance L dec =2mH.

[0124] In order to verify the effectiveness of the method of the present invention, a method for improving the grid-connected stability of a grid-connected converter based on inductor current feedforward and coupling enhancement, a 2kW experimental platform was built to verify the effectiveness of the control method.

[0125] Figure 4 The following diagram shows the inverter output voltage and current waveforms before this method was applied. As can be seen from the figure, when the voltage controller proportional coefficient kpv changes from 0.6 to 0.27, the inverter output current exhibits divergent oscillations, triggering protection and causing the inverter to stop operating. Figure 5 The following figure shows the inverter output voltage and current waveforms after adopting this method. As can be seen from the figure, after adopting this method, under the same working conditions, the inverter output current does not oscillate and can be connected to the grid and operate stably.

[0126] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0127] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

[0128] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

Claims

1. A method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement, characterized in that: include: Step S1: Collect the inverter port voltage v a 、v b 、v c and the filter inductor current i a 、i b 、i c And the d-axis sampling port voltage v is obtained by abc / dq coordinate transformation d , q-axis sampling port voltage v q and d-axis sampling filter inductor current i d , q-axis sampling filter inductor current i q ; Step S2: By v d 、v q 、i d 、i q Calculate the inverter output active power and reactive power; Step S3: Calculate the phase and amplitude of the port voltage reference according to the active power and reactive power and their reference values, and further obtain the d-axis voltage reference value v dref and q-axis voltage reference value v qref ; Step S4: subtracting the dq axis port voltage reference value from the dq axis sampling port voltage, and further calculating the dq axis current error, and adding the dq axis current error to the dq axis feedforward inductor current to obtain the dq axis inductor current reference value; Step S5: The difference between the d-axis and q-axis inductor current reference values and the d-axis and q-axis sampled inductor currents is used as the input of the d-axis and q-axis current regulators. The d-axis current regulator output is added with the d-axis feedforward port voltage and subtracted with the d-axis coupling voltage to obtain a d-axis modulated wave. The q-axis current regulator output is added with the q-axis feedforward port voltage and added with the q-axis coupling voltage to obtain a q-axis modulated wave. The q-axis coupling voltage is the product of the d-axis inductor current and the coupling enhancement coefficient, and the d-axis coupling voltage is the product of the q-axis inductor current and the coupling enhancement coefficient. Step S6: The dq axis modulation wave is transformed into the abc coordinate system modulation wave through dq / abc coordinate transformation, and a driving signal is generated through space vector modulation.

2. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 1, characterized in that: In step S1, the abc / dq coordinate system is transformed from a three-phase stationary coordinate system to a two-phase rotating coordinate system. The transformation formula for converting the three-phase stationary reference system voltage to the two-phase rotating reference system voltage is: Where: θ is the phase of the port voltage reference; The transformation formula for converting the three-phase stationary coordinate system current to the two-phase rotating coordinate system current is:

3. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 1, characterized in that: The inverter outputs active power and reactive power respectively: p=1.5×(v d i d +v q i q ) q=1.5×(v q i d -v d i q ) Where: p is the active power output by the inverter, and is the reactive power output by the inverter.

4. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 3, characterized in that: The step S3 comprises: Step S3-1: Calculate the phase of the port voltage reference based on the inverter output active power and its reference value: Where: θ is the phase of the port voltage reference, P ref is the inverter output active power reference value, ω n is the rated angular frequency of the three-phase power grid, D p is the active damping coefficient, J is the virtual moment of inertia, and s is the Laplace operator; Step S3-2: Calculate the amplitude of the port voltage reference based on the inverter output, reactive power, and reference value: Where: E m is the amplitude of the port voltage reference value, Q ref is the inverter output reactive power reference value, V n is the rated voltage amplitude of the three-phase power grid, v amp is the amplitude of the port voltage, D q is the reactive damping coefficient, K is the reactive inertia coefficient; Step S3-3: Calculate the port voltage reference value based on the phase and amplitude of the port voltage reference: Where: v ref is the port voltage reference value.

5. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 3, characterized in that: The step S4 comprises: Step S4-1: dq axis port voltage reference v dref and v qref Respectively with the dq axis port voltage v d and v q The difference is used as the input of the voltage regulator to obtain the dq axis current error: Δi d =H v (s)(v dref -v d ) Δi q =H v (s)(v qref -v q ) Where: Δi d is the d-axis current error, Δi q is the q-axis current error, H v (s) is the transfer function of the voltage regulator Step S4-2: Add the dq axis current error to the dq axis feedforward inductor current to obtain a dq axis inductor current reference value: i dref =Δi d +i d i qref =Δi q +i q Where: i dref is the d-axis inductor current reference value, i qref is the q-axis inductor current reference value.

6. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 5, characterized in that: The step S5 comprises: Step S5-1: Subtract the dq axis inductor current reference value from the dq axis sampled inductor current and obtain the following through the current regulator: Δv d1 =H i (s)(i dref -i d ) Δv q1 =H i (s)(i qref -i q ) Where: Δv d1 is the first error current of the d-axis, Δv q1 is the first error current of q axis, H i (s) is the transfer function of the current regulator; Step S5-2: d-axis inductor current i d Multiply by the coupling enhancement coefficient -ωL dec Get the q-axis coupling voltage Δv d2 , q-axis inductor current i q Multiply by the coupling enhancement coefficient -ωL dec Get the d-axis coupling voltage Δv q2 ; Step S5-3: d-axis first error current Δv d1 Add the d-axis feedforward port voltage v d And subtract the d-axis coupling voltage Δv d2 Get the d-axis modulation wave m d ; q-axis first error current Δv q1 Add the q-axis feedforward port voltage v q And add the d-axis coupling voltage Δv q2 Get the q-axis modulation wave m q : m d =Δv d1 -Δv d2 +v d m q =Δv q1 +Δv q2 +v q Δv d2 =-i q oh n L dec Δv q2 =-i d oh n L dec Where: L dec Increase inductance for coupling.

7. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 6, characterized in that: The step S6 comprises: Step S6-1: The obtained dq axis modulated wave is transformed into a three-phase stationary coordinate system through dq / abc coordinate transformation to obtain the abc coordinate system modulated wave: Step S6-2: The abc coordinate system modulated wave is sent to the PWM module to generate a drive signal to control the inverter; the modulated wave is compared with the three-phase triangular carrier and a drive signal is generated through the space vector modulation method.

8. The method for improving grid-connected stability of a grid-connected inverter based on inductor current feedforward and coupling enhancement according to claim 1, characterized in that: The grid-type inverter includes: a DC side power supply, a three-phase inverter, a three-phase grid impedance and a three-phase grid.

9. A device for improving grid-connected stability of a grid-connected inverter based on inductive current feedforward and coupling enhancement, comprising a memory, a processor, and a program stored in the memory, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A storage medium having a program stored thereon, characterized in that: When the program is executed, the method according to any one of claims 1 to 8 is implemented.

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