Grid-connected inverter anti-interference capability improvement control method based on passivity theory

Abstract

The invention discloses a grid-connected inverter anti-interference capability improvement control method based on a passivity theory, belongs to the technical field of grid-connected inverter control, solves the problem of how to improve the anti-interference capability of a grid-following type grid-connected inverter under a weak power grid, and sets n inverters to operate in a grid-following type mode, k inverters in the system are changed from running in a network following mode to running in a network constructing mode, the control process is ended, the k inverters in the system run in the network constructing mode, the n-k inverters run in the network following mode, and the anti-interference capability of the n-k inverters is improved. The anti-interference capability of other grid-following type inverters at the same PCC point can be improved only by selecting a part of inverters from the n parallel grid-following type inverters to be changed into the operation mode of the grid-constructing type inverters.

Description

Technical Field

[0001] This invention belongs to the field of grid-connected inverter control technology, and relates to a control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory. Background Technology

[0002] As a key interface for grid-connected renewable energy power generation, the control performance of grid-connected inverters is crucial for multi-inverter power plants. Inverters mainly employ two control methods: grid-following and grid-connected. Grid-following control is widely used due to its fast response speed and ability to operate at the maximum power point of renewable energy sources. With the increasing penetration rate of renewable energy generation, the power grid is gradually shifting from being primarily synchronous generator-based to inverter-driven, resulting in weak grid or even extremely weak grid characteristics.

[0003] On the one hand, these inverters typically employ linear controllers, such as proportional-integral (PI) control, which is designed based on linear theory. However, when nonlinear changes occur in the power grid due to the instability and volatility of renewable energy sources—such as the plug-and-play nature of inverters in multi-inverter power plants, large fluctuations in grid impedance, and random changes in the inverter's operating point—the grid structure and parameters change randomly. In such cases, control schemes based on linear theory may not be able to ensure system stability.

[0004] On the other hand, to maintain the stability of grid-connected inverters in weak grid conditions, it is necessary to reduce the PLL bandwidth or adjust the PLL structure. However, adjusting the PLL bandwidth or structure will significantly reduce the power immunity of the grid-connected inverter, making its output power susceptible to overshoot caused by power fluctuations from other grid-connected inverters connected at the same PCC point, ultimately leading to shutdown. Therefore, improving the power immunity of grid-connected inverters is crucial.

[0005] Previous studies have shown that weak power grids can exhibit problems such as broadband oscillations in the nonlinear frequency domain, posing significant stability challenges to grid-connected inverters. Existing techniques, such as "Research on the Influence of Phase-Locked Loop on the Stability of LCL-type Grid-Connected Inverters under Weak Power Grid Conditions and PLL Parameter Design" (Proceedings of the CSEE, 2014, Vol. 34, No. 30, pp. 5259-5268), reduce the bandwidth of the PLL in grid-connected inverters based on phase margin, thus improving the stability of grid-connected inverters under weak power grid conditions. However, this method requires a significant reduction in PLL bandwidth under extremely weak power grid conditions, which not only reduces the inverter's speed but also its power immunity.

[0006] For example, in the IEEE Transactions on Industrial Electronics, Vol. 70, pp. 12421–12430, 2014, a passive controller was designed for grid-connected inverters, which achieved distributed, coordinated, and stable operation of grid-connected inverter plants and could adapt to changes in nonlinear grid structure parameters. However, the design of a passive controller for grid-connected inverter control still remains a gap.

[0007] For example, the invention patent with application publication number CN118199150A discloses a robust control method for a passive LCL grid-connected inverter. By introducing a nonlinear control delay and adopting the D-segmentation method to design the control parameters of the passive feedback controller, the parameter stability domain that meets the stability index constraints is obtained, which increases the stability margin of the LCL grid-connected inverter based on the phase-locked loop oriented grid-connected mode when the grid impedance fluctuates greatly. However, it is still difficult to guarantee its disturbance rejection capability.

[0008] For example, the invention patent with publication number CN118826133A discloses a passive grid-connected inverter dual-mode fusion control method. This method aims to enable a single inverter to simultaneously possess the characteristics of both passive grid-connected and grid-connected modes, thereby improving its stability under large fluctuations in the grid short-circuit ratio. However, this method can only improve the ability to resist external grid disturbances, and cannot directly resist the ability to resist power disturbances from other inverters at the same node. When applying the above method to other inverters at the same node on a large scale, it is necessary to shut down all inverters and modify the control algorithm, which is extremely costly. Summary of the Invention

[0009] The technical problem to be solved by this invention is how to improve the anti-interference ability of grid-connected inverters against other grid-connected inverters at the same node of a weak grid.

[0010] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0011] A control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory is applied to a system with multiple grid-connected inverters in parallel, including the following steps:

[0012] Step 1: Set all n inverters to operate in grid-connected mode, and denote the grid connection point as the PCC point; where n is a positive integer and n>1;

[0013] Step 2: Based on the passive theory, establish the passive feedback control law for the following network control mode and the passive feedback control law for the network control mode respectively.

[0014] Step 3: Change the k inverters in the system from grid-connected mode to grid-connected mode, k = 0, 1, 2, ..., n-1; where the choice of k depends on the requirements for the disturbance rejection capability of the grid-connected inverters, the higher the requirement, the larger k will be;

[0015] Step 4: End this control process. There are k inverters in the system operating in grid-connected mode and nk inverters operating in grid-following mode. The anti-interference capability of nk inverters is improved.

[0016] Furthermore, the inverter includes a DC source, a three-phase inverter bridge, and an LC filter connected in series; the LC filter includes an equivalent resistance r connected in series. f Filter inductor L f and filter capacitor C f The equivalent resistance r f The non-series terminal is connected to the output terminal of the three-phase inverter bridge, and multiple filter capacitors C f The non-series terminals are connected together, and the filter inductor L f and filter capacitor C f The common connection point is used as the grid connection point;

[0017] It also includes DC capacitor C dc The DC capacitor C dc The two ends are connected to the positive and negative terminals of a DC source, respectively.

[0018] Furthermore, the control rules for the n inverters mentioned in step 1 are as follows:

[0019] Step 1.1, sample the three-phase grid output grid-connected currents i ga i gb i gc The sampled PCC point voltages are u pcca u pccb u pccc ;

[0020] Step 1.2, take the PCC point voltage u obtained in step 1.1 as an example. pcca u pccb u pccc The phase angle θ of the voltage at point PCC is obtained by phase-locking through a phase-locked loop (PLL). Using the voltage transformation equation, the d-axis component u of the voltage at point PCC is obtained by transforming from a three-phase stationary coordinate system to a two-phase rotating coordinate system. pccd q-axis component u pccq ;

[0021] Step 1.3: Based on the phase angle θ of the PCC point voltage obtained in Step 1.2, use the current transformation equation to transform the output grid-connected current i sampled in Step 1.1. ga igb i gc Transformed into the d-axis component of the output grid-connected current in a two-phase rotating coordinate system gd q-axis component i gq .

[0022] Furthermore, in step 1.2, the voltage phase angle θ at point PCC is represented using the following logic:

[0023]

[0024] Where ω0 is the rated angular frequency of the voltage at point PCC, K p_PLL K is the proportional control coefficient of the phase-locked loop PI controller. i_PLL is the integral control coefficient of the phase-locked loop PI controller, and s is the Laplace operator.

[0025] Furthermore, in step 1.2, the voltage transformation equation is expressed using the following logic:

[0026]

[0027] Furthermore, in step 1.3, the current transformation equation is represented using the following logic:

[0028]

[0029] Furthermore, the passive feedback control law of the following network control mode described in step 2 is specifically as follows:

[0030] Step 2.1.1, under grid-connected mode operation, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation:

[0031]

[0032] Among them, Q ref U is the rated reactive power command value output by the grid-connected inverter, and U is the effective value of the three-phase grid voltage.

[0033] Step 2.1.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows:

[0034]

[0035] Among them, u d1 u q1 These are the d-axis and q-axis modulation voltages of the modulation voltage in a grid-type control mode designed based on passive theory, respectively. f r is the equivalent resistance of the inductance on the bridge arm side. L1To inject damping gain into the mesh pattern, L f For the bridge arm side filter inductor, These are the setpoint values ​​for the d-axis components of the output grid-connected current command signal. and the q-axis component setpoint of the output grid-connected current command signal Take the derivative with respect to time t.

[0036] Furthermore, the passive feedback control law of the network-type control mode described in step 2 is specifically as follows:

[0037] Step 2.2.1, under the grid-connected operation mode, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation:

[0038]

[0039] Among them, C f For the filter capacitor, r m1 For the first injection damping gain of the network-type mode, u pccd * u pccq * These are the given values ​​for the d-axis component and q-axis component of the output voltage of the filter capacitor, respectively. These are the d-axis components of the output voltage of the filter capacitor. and the q-axis component of the output grid-connected current command signal Differentiate with respect to time t;

[0040] Step 2.2.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows:

[0041]

[0042] Among them, u d2 u q2 These are the d-axis and q-axis modulation voltages of the modulation voltage in a network-type control mode designed based on passive theory, respectively. m2 For the second injection damping gain in the network-type mode, These are the d-axis component setpoints of the output grid-connected current command signal. and q-axis component given value Take the derivative with respect to time t.

[0043] The advantages of this invention are:

[0044] (1) The passive controller designed based on nonlinear theory in this invention can make the inverter remain stable under complex nonlinear changes in grid state and parameters. Its stability in high-penetration new energy grid is better than that of controllers designed under traditional linear framework. Without large-scale modification of existing equipment, it is only necessary to replace some of the original grid-type inverters at the PCC point with grid-type inverters to improve the power disturbance rejection capability of the remaining grid-type inverters at the PCC point. The system does not need to increase the additional hardware cost and realizes the plug-and-play of inverters.

[0045] (2) This invention does not require reducing the phase-locked loop bandwidth of the grid-connected inverter. It directly adopts the original grid-connected control strategy and can ensure the stable operation of the grid-connected inverter in weak grids or even extremely weak grids without any modifications. This improves the speed and anti-interference capability of the grid-connected inverter under complex grids.

[0046] (3) The passive controller designed based on the passive theory of the present invention only needs to select some inverters among the n parallel grid-connected inverters and change them to the operation mode of grid-connected inverters to improve the anti-interference capability of the other grid-connected inverters at the same PCC point. Compared with the original method of improving the stability of each inverter from the perspective of a single machine, the present invention also realizes the improvement of the anti-interference capability of the inverter from the perspective of multiple machines by the synergy of grid-connected inverters and grid-connected inverters, ensuring that the entire station has good stability and anti-interference performance, and achieving the effect of system stability and anti-interference.

[0047] (3) This patent designs the control of grid-connected and grid-connected inverters based on passive theory, and utilizes the mutual synergy between grid-connected and grid-connected inverters to improve the anti-interference capability of grid-connected inverters. The design protection of this patent is: the synergistic effect of passively designed grid-connected and grid-connected inverters. Attached Figure Description

[0048] Figure 1 This is a topology diagram of a parallel system of multiple grid-connected inverters according to Embodiment 1 of the present invention;

[0049] Figure 2 This is a simulation waveform diagram of the power disturbance experienced by the grid-connected inverter when all inverters are operating in grid-connected mode under weak grid conditions in Embodiment 1 of the present invention.

[0050] Figure 3 This is a simulation waveform diagram of the power disturbance experienced by the remaining grid-connected inverters after the inverters in the weak grid under Embodiment 1 of the present invention change their operating mode. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0053] Example 1

[0054] like Figure 1 Specifically, a control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory is disclosed, which is applied to a system with multiple grid-connected inverters in parallel.

[0055] On the DC side, the inverter includes a DC source, a three-phase inverter bridge, and an LC filter connected in series; the LC filter includes the equivalent resistance r of the bridge arm inductors connected in series. f Filter inductor L f and filter capacitor C f The equivalent resistance r f The non-series terminal is connected to the output terminal of the three-phase inverter bridge, and multiple filter capacitors C f The non-series terminals are connected together, and the filter inductor L f and filter capacitor C f The common connection point is used as the grid connection point;

[0056] It also includes DC capacitor C dc The DC capacitor C dc The two ends are connected to the positive and negative terminals of a DC source, respectively. Figure 1 China V dc This is the DC side voltage.

[0057] like Figure 1 As shown, a line inductance L is installed on the grid side. g and three-phase power grid e gabc Line inductance L g One end is connected to point PCC, and the line inductance L g The other end is connected to the three-phase power grid. gabc .

[0058] Furthermore, the control method includes the following steps:

[0059] Step 1: Set all n inverters to operate in grid-connected mode, and denote the grid connection point as PCC point; where n is a positive integer and n>1.

[0060] In this embodiment, the control law for the n inverters includes the following steps:

[0061] Step 1.1, sample the three-phase grid output grid-connected currents i ga i gb i gc The sampled PCC point voltages are u pcca u pccb u pccc .

[0062] Specifically, in this embodiment, the grid-connected current output from the three-phase grid in the grid-connected system is collected by a current sensor, and the voltage value at the PCC point is collected by a voltage sensor. The selection of the sampling ratio coefficients of the current sensor and the voltage sensor depends on the requirements for the anti-interference capability of the grid-connected inverter.

[0063] Step 1.2, take the PCC point voltage u obtained in step 1.1 as an example. pcca u pccb u pccc The phase angle θ of the voltage at point PCC is obtained by phase locking through a phase-locked loop (PLL). The following logic is used to represent the phase angle θ of the voltage at point PCC:

[0064]

[0065] Where ω0 is the rated angular frequency of the voltage at point PCC, K p_PLL K is the proportional control coefficient of the phase-locked loop PI controller. i_PLL ω0 is the integral control coefficient of the phase-locked loop PI controller, and s is the Laplace operator. In this embodiment, ω0 and K are... p_PLL and K i_PLL Selected based on the actual needs of the engineering personnel.

[0066] Using the voltage transformation equation, the d-axis component u of the voltage at point PCC is obtained through a transformation from a three-phase stationary coordinate system to a two-phase rotating coordinate system. pccd q-axis component u pccq The voltage transformation equation can be expressed using the following logic:

[0067]

[0068] Step 1.3: Based on the phase angle θ of the PCC point voltage obtained in Step 1.2, use the current transformation equation to transform the output grid-connected current i sampled in Step 1.1. ga i gb i gc Transformed into the d-axis component of the output grid-connected current in a two-phase rotating coordinate system gd q-axis component i gq .

[0069] Step 2: Based on the passive theory, establish the passive feedback control law for the following network control mode and the passive feedback control law for the network control mode respectively.

[0070] In this embodiment, the passive feedback control law of the following network control mode includes the following steps:

[0071] Step 2.1.1, under grid-connected mode operation, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation:

[0072]

[0073] Among them, Q ref U is the rated reactive power command value output by the grid-connected inverter, and U is the effective value of the three-phase grid voltage.

[0074] Step 2.1.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows:

[0075]

[0076] Among them, u d1 u q1 These are the d-axis and q-axis modulation voltages of the modulation voltage in a grid-type control mode designed based on passive theory, respectively. f r is the equivalent resistance of the inductance on the bridge arm side. Lf To inject damping gain into the mesh pattern, L f For the bridge arm side filter inductor, These are the setpoint values ​​for the d-axis components of the output grid-connected current command signal. and the q-axis component setpoint of the output grid-connected current command signal Take the derivative with respect to time t.

[0077] In this embodiment, the passive feedback control law of the network-type control mode includes the following steps:

[0078] Step 2.2.1, under the grid-connected operation mode, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation:

[0079]

[0080] Among them, C f For the filter capacitor, r m1 For the first injection damping gain of the network-type mode, u pccd * u pccq* These are the given values ​​for the d-axis component and q-axis component of the output voltage of the filter capacitor, respectively. These are the d-axis components of the output voltage of the filter capacitor. and the q-axis component of the output grid-connected current command signal Differentiate with respect to time t;

[0081] Step 2.2.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows:

[0082]

[0083] Among them, u d2 u q2 These are the d-axis and q-axis modulation voltages of the modulation voltage in a network-type control mode designed based on passive theory, respectively. m2 For the second injection damping gain in the network-type mode, These are the d-axis component setpoints of the output grid-connected current command signal. and q-axis component given value Take the derivative with respect to time t.

[0084] In this embodiment, r Lf r m1 r m2 The larger the value of , the better the damping of the system.

[0085] Step 3: Change the k inverters in the system from grid-connected mode to grid-connected mode, k = 0, 1, 2, ..., n-1; where the choice of k depends on the requirements for the disturbance rejection capability of the grid-connected inverters, the higher the requirement, the larger k is.

[0086] Step 4: End this control process. There are k inverters in the system operating in grid-connected mode and nk inverters operating in grid-following mode. The anti-interference capability of nk inverters is improved.

[0087] Based on this, the present invention provides the following set of embodiment data to illustrate the grid-connected inverter disturbance rejection capability improvement control method based on passive theory provided by the present invention:

[0088] In this embodiment, n=3, and the weak grid includes three inverters, denoted as Inverter 1, Inverter 2, and Inverter 3. These three inverters are initially operated in grid-connected mode. With k=1, inverter 3 is selected to change from grid-connected mode to grid-connected mode. The DC-side voltage V of each inverter... dc =770V, filter inductor L f =0.9mH, filter capacitor C f=11.6μF, equivalent resistance r of bridge arm side inductance f = 2.18Ω, line inductance L g = 3.85mH, the rated output line voltage of the inverter is 380V / 50Hz, and the rated power of a single inverter is 20kW. To demonstrate the technical effectiveness of this embodiment in achieving the anti-interference capability of the grid-connected inverter, the sampling ratio coefficient of the current sensor in step 1.1 is 10, and the sampling ratio coefficient of the voltage sensor is 120; in step 1.2, ω0 is 314rad / s, K p_PLL K is 0.28. i_PLL The value is 12; based on the above data, MATLAB / Simulink simulation was performed to obtain... Figures 2-3 .

[0089] In this example, to demonstrate the effectiveness of the invention, a MATLAB / Simulink simulation was performed.

[0090] like Figure 2 As shown, the three inverters initially operate in grid-connected mode. Inverter 1 and inverter 3 maintain a rated output power of 20kW. When the output power command of inverter 2 jumps from 10kW to 20kW, inverter 1 and inverter 3 do not execute steps 2 to 4. The power of inverter 1 fluctuates significantly, with an instantaneous peak value close to 28kW.

[0091] like Figure 3 As shown, when inverter 1 and inverter 3 maintain a rated output power of 20kW, and the output power command of inverter 2 jumps from 10kW to 20kW, inverter 3 is changed from grid-following mode to grid-connected mode. The power disturbance of inverter 1 is significantly reduced, the instantaneous peak value is less than 25kW, and the recovery time after the power disturbance is also significantly shortened.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory, applied to a parallel system of multiple grid-connected inverters, characterized in that, Includes the following steps: Step 1: Set all n inverters to operate in grid-connected mode, and denote the grid connection point as the PCC point; where n is a positive integer and n>1; Step 2: Based on the passive theory, establish the passive feedback control law for the following network control mode and the passive feedback control law for the network control mode respectively. Step 3: Change the k inverters in the system from grid-connected mode to grid-connected mode, k = 0, 1, 2, ..., n-1; where the choice of k depends on the requirements for the disturbance rejection capability of the grid-connected inverters, the higher the requirement, the larger k will be; Step 4: End this control process. There are k inverters in the system operating in grid-connected mode and nk inverters operating in grid-following mode. The anti-interference capability of nk inverters is improved.

2. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 1, characterized in that, The inverter includes a DC source, a three-phase inverter bridge, and an LC filter connected in series; the LC filter includes an equivalent resistance r connected in series. f Filter inductor L f and filter capacitor C f The equivalent resistance r f The non-series terminal is connected to the output terminal of the three-phase inverter bridge, and multiple filter capacitors C f The non-series terminals are connected together, and the filter inductor L f and filter capacitor C f The common connection point is used as the grid connection point; It also includes DC capacitor C dc The DC capacitor C dc The two ends are connected to the positive and negative terminals of the DC source, respectively.

3. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 1, wherein the control law for the n inverters in step 1 is specifically as follows: Step 1.1, sample the three-phase grid output grid-connected currents i ga i gb i gc The sampled PCC point voltages are u pcca u pccb u pccc ; Step 1.2, take the PCC point voltage u obtained in step 1.1 as an example. pcca u pccb u pccc The phase angle θ of the voltage at point PCC is obtained by phase-locking through a phase-locked loop (PLL). Using the voltage transformation equation, the d-axis component u of the voltage at point PCC is obtained by transforming from a three-phase stationary coordinate system to a two-phase rotating coordinate system. pccd q-axis component u pccq ; Step 1.3: Based on the phase angle θ of the PCC point voltage obtained in Step 1.2, use the current transformation equation to transform the output grid-connected current i sampled in Step 1.

1. ga i gb i gc Transformed into the d-axis component of the output grid-connected current in a two-phase rotating coordinate system gd q-axis component i gq .

4. In the control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 3, the voltage phase angle θ at the PCC point is represented by the following logic in step 1.2: in, ω0 is the rated angular frequency of the voltage at point PCC, K p_PLL K is the proportional control coefficient of the phase-locked loop PI controller. i_PLL is the integral control coefficient of the phase-locked loop PI controller, and s is the Laplace operator.

5. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 3, wherein the voltage transformation equation in step 1.2 is expressed using the following logic:

6. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 3, wherein the current transformation equation in step 1.3 is expressed using the following logic:

7. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 1, wherein the passive feedback control law of the grid-connected control mode in step 2 is specifically as follows: Step 2.1.1, under grid-connected mode operation, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation: in, Q ref U is the rated reactive power command value output by the grid-connected inverter, and U is the effective value of the three-phase grid voltage. Step 2.1.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows: Among them, u d1 u q1 These are the d-axis and q-axis modulation voltages of the modulation voltage in a grid-type control mode designed based on passive theory, respectively. f r is the equivalent resistance of the inductance on the bridge arm side. L1 To inject damping gain into the mesh pattern, L f For the bridge arm side filter inductor, These are the setpoint values ​​for the d-axis components of the output grid-connected current command signal. and the q-axis component setpoint of the output grid-connected current command signal Take the derivative with respect to time t.

8. The control method for improving the disturbance rejection capability of grid-connected inverters based on passive theory according to claim 3, wherein the passive feedback control law of the grid-type control mode in step 2 is specifically as follows: Step 2.2.1, under the grid-connected operation mode, record the d-axis component setpoint and q-axis component setpoint of the grid-connected current command signal output by the dq axis as follows: Using the following logical representation: in, C f For the filter capacitor, r m1 For the first injection damping gain of the network-type mode, u pccd * u pccq * These are the given values ​​for the d-axis component and q-axis component of the output voltage of the filter capacitor, respectively. These are the d-axis components of the output voltage of the filter capacitor. and the q-axis component of the output grid-connected current command signal Differentiate with respect to time t; Step 2.2.2, based on the interconnection and damping distribution passive control method, the expression of the network-type passive feedback control law is obtained as follows: Among them, u d2 u q2 These are the d-axis and q-axis modulation voltages of the modulation voltage in a network-type control mode designed based on passive theory, respectively. m2 For the second injection damping gain in the network-type mode, These are the d-axis component setpoints of the output grid-connected current command signal. and q-axis component given value Take the derivative with respect to time t.

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