Multi-network converter control method based on active disturbance rejection virtual impedance and related device

Abstract

The invention discloses a multi-network-construction-type converter control method based on active disturbance rejection virtual impedance and a related device, and the method comprises the steps: obtaining a grid-connected reactive instruction, and controlling n actual output currents and n actual output voltages corresponding to n network-construction-type converters through n matching control modules, determining n actual reactive power output powers corresponding to the n network construction type converters based on the n actual output currents and the n actual output voltages, and determining n voltage reference signals based on the n actual reactive power output powers and the n preset reactive power output powers through a reactive power control module, n voltage compensation signals are determined based on the n actual output currents through the active disturbance rejection virtual impedance control module, and the n actual output voltages are adjusted through the voltage and current double-loop control module, so that the n actual output voltages are adjusted to be n target output voltages. According to the embodiment of the invention, the operation stability of the new energy grid-connected system can be improved.

Description

Technical Field

[0001] This invention relates to the field of new energy grid connection technology, and in particular to a control method and related device for a multi-grid converter based on self-rejection virtual impedance. Background Technology

[0002] Parallel operation of multiple grid-type converters in new energy grid-connected systems has become the mainstream architecture for large-scale new energy development. This architecture can flexibly adapt to the access requirements of distributed power sources such as photovoltaics and wind power, effectively improving energy utilization efficiency. However, it faces significant technical challenges in practical applications. The inherent differences in line impedance among multiple converters and the difficulty in achieving perfect consistency in device parameters, coupled with fluctuations in new energy output leading to imbalances in converter output characteristics, can easily cause inconsistent output voltages among converters. This can trigger circulating currents between converters, increasing system losses, exacerbating the heating of switching devices, deteriorating power quality, and affecting the stable and reliable operation of the grid-connected system. Therefore, improving the stability of new energy grid-connected systems is an urgent problem to be solved. Summary of the Invention

[0003] This application provides a control method and related device for a multi-grid converter based on self-rejection virtual impedance, which can improve the stability of the operation of the new energy grid-connected system.

[0004] In a first aspect, this application provides a control method for multi-grid converters based on active disturbance rejection virtual impedance. This method is applied to a renewable energy grid-connected system, which includes n grid-connected converters, n matching control modules, a reactive power control module, a voltage-current dual-loop control module, and an active disturbance rejection virtual impedance control module. Each grid-connected converter corresponds to one matching control module, and n is a positive integer. The control method for multi-grid converters based on active disturbance rejection virtual impedance includes: Obtain grid-connected reactive power instructions; the grid-connected reactive power instructions include n preset reactive power outputs corresponding to the n grid-type converters; each grid-type converter corresponds to one preset reactive power output. By controlling the actual output current and actual output voltage of each of the n grid-type converters through the n matching control modules, n actual output currents and n actual output voltages are obtained. The n actual reactive power outputs corresponding to the n grid-type converters are determined based on the n actual output currents and the n actual output voltages. The reactive power control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs. The self-disruption rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; the n target output voltages are all equal, which reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0005] Secondly, this application provides a multi-grid converter control device based on active disturbance rejection virtual impedance. This device is applied to a new energy grid-connected system, which includes n grid-connected converters, n matching control modules, a reactive power control module, a voltage-current dual-loop control module, and an active disturbance rejection virtual impedance control module. Each grid-connected converter corresponds to one matching control module, and n is a positive integer. The multi-grid converter control device based on active disturbance rejection virtual impedance includes an acquisition unit and a processing unit. The acquisition unit is used to acquire grid-connected reactive power instructions; the grid-connected reactive power instructions include n preset reactive power outputs corresponding to the n grid-type converters; each grid-type converter corresponds to one preset reactive power output. The processing unit is used to control the actual output current and actual output voltage of each of the n grid-type converters through the n matching control modules, so as to obtain n actual output currents and n actual output voltages. The n actual reactive power outputs corresponding to the n grid-type converters are determined based on the n actual output currents and the n actual output voltages. The reactive power control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs. The self-disruption rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; the n target output voltages are all equal, which reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0006] Thirdly, embodiments of the present invention provide an electronic device, including: a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor to cause the electronic device to perform the method as described in the first aspect.

[0007] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that is executed by a processor to implement the method as described in the first aspect.

[0008] Fifthly, embodiments of the present invention provide a computer program product including a non-transitory computer-readable storage medium storing a computer program, such that a computer performs the method as described in the first aspect.

[0009] Implementing the embodiments of the present invention has the following beneficial effects: As can be seen, the multi-grid converter control method based on self-rejection virtual impedance described in this embodiment of the invention is applied to a new energy grid-connected system. The new energy grid-connected system includes n grid-connected converters, n matching control modules, a reactive power control module, a voltage-current dual-loop control module, and a self-rejection virtual impedance control module. Each grid-connected converter corresponds to one matching control module, and n is a positive integer. First, the grid-connected reactive power command is obtained, which includes n preset reactive power outputs corresponding to the n grid-connected converters. Each grid-connected converter corresponds to one preset reactive power output. Then, the actual output current and actual output voltage of each of the n grid-connected converters are controlled by the n matching control modules to obtain n actual output currents and n actual output voltages. Next, based on the n actual output currents and n actual output voltages, the n actual reactive power outputs corresponding to the n grid-connected converters are determined. Then, the reactive power control module... Based on the n actual reactive power outputs and the n preset reactive power outputs, n voltage reference signals are determined. Then, the self-interference rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. Finally, the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages, wherein the n target output voltages are all equal. This reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0011] Figure 1 This is a schematic diagram of the structure of a new energy grid-connected system provided in the embodiments of this application; Figure 2 This is a flowchart of a multi-grid converter control method based on self-rejection virtual impedance provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of a self-interference rejection virtual impedance control module provided in an embodiment of this application; Figure 4 This is a block diagram of a self-interference rejection virtual impedance control provided in an embodiment of this application; Figure 5 This is a control block diagram of a grid-connected new energy system with virtual impedance matching control provided in an embodiment of this application; Figure 6 This is a comparison diagram of the circulating current state before and after adjusting the actual output voltage of n grid-type converters, provided by an embodiment of this application. Figure 7 This is a schematic diagram of the structure of a multi-grid converter control device based on self-rejection virtual impedance provided in the embodiments of this application; Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0012] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0013] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0014] In this specification, the term "implementation" means that a specific feature, structure, or characteristic described in connection with an implementation may be included in at least one implementation of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same implementation, nor is it a mutually exclusive, independent, or alternative implementation. Those skilled in the art will understand, explicitly and implicitly, that the implementations described herein can be combined with other implementations.

[0015] Please see Figure 1 , Figure 1 This is a schematic diagram of a new energy grid-connected system provided in this application. The new energy grid-connected system includes n grid-type converters, n matching control modules, a reactive power control module, a voltage and current dual-loop control module, and a self-interference rejection virtual impedance control module. Each grid-type converter corresponds to one matching control module. In this embodiment, firstly, a grid-connected reactive power command is obtained, which includes n preset reactive power outputs corresponding to the n grid-type converters. Each grid-type converter corresponds to one preset reactive power output. Then, the actual output current and actual output voltage of each of the n grid-type converters are controlled by the n matching control modules to obtain n actual output currents and n actual output voltages. Then, based on the n actual output currents and n actual output voltages, the n actual reactive power outputs corresponding to the n grid-type converters are determined. Finally, the reactive power control module... The control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs. Then, the self-interference rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. Finally, the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages, wherein the n target output voltages are all equal, thereby reducing the circulating current value among the n grid-connected converters and improving the stability of the new energy grid-connected system.

[0016] As can be seen, the matching control module first accurately collects the actual output current and voltage of each converter, providing a reliable feedback basis for subsequent control. Then, the reactive power control module generates a voltage reference signal based on the deviation between the actual and preset reactive power output, ensuring that each converter accurately undertakes reactive power according to the grid connection command and meets the reactive power demand of the grid. The active disturbance rejection virtual impedance control module generates a targeted voltage compensation signal based on the actual output current, which can actively offset internal and external disturbances such as line impedance differences and device parameter deviations, effectively suppressing the generation of abnormal circulating current. Finally, the voltage and current dual-loop control module integrates the voltage reference signal and the compensation signal, and uniformly adjusts the actual output voltage of all converters to the same target output voltage, reducing the voltage difference between converters from the root, reducing the circulating current value, and improving the voltage support capability of the system under disturbance or fault conditions. Ultimately, this ensures the safe and reliable operation of the new energy grid-connected system, optimizes current sharing performance, and ensures stable grid connection. By integrating the synergistic effects of matching control, reactive power control, self-disturbance rejection virtual impedance control, and voltage-current dual-loop control, the system achieves precise reactive power distribution, effective circulating current suppression, and improved operational stability in a multi-grid converter parallel system.

[0017] Please see Figure 2 , Figure 2 This is a flowchart of a multi-grid converter control method based on self-rejection virtual impedance provided in this application, including but not limited to the following steps: S201: Obtain grid-connected reactive power command.

[0018] In this embodiment, the grid-connected reactive power command includes n preset reactive power outputs corresponding to the n grid-type converters, with each grid-type converter corresponding to one preset reactive power output.

[0019] Grid-connected reactive power commands can be issued by the power grid dispatch center to regulate the reactive power output of new energy grid-connected systems, so as to meet the grid's requirements for voltage support, power factor, and other indicators. The n preset reactive power outputs corresponding to the n grid-connected converters can be determined according to the rated capacity ratio of each converter, or can be set by operators according to the preset capacity ratio to ensure that the reactive power distribution among multiple converters achieves the expected effect.

[0020] S202: By controlling the actual output current and actual output voltage of each of the n grid-type converters through the n matching control modules, n actual output currents and n actual output voltages are obtained.

[0021] In this embodiment, each matching control module acquires the electrical signals at the output of the corresponding grid-connected converter in real time through integrated voltage and current sensors. The acquired raw electrical signals are filtered, denoised, and their amplitude and phase are calibrated to obtain accurate real-time current and voltage data. Simultaneously, based on the grid's frequency and phase reference, the matching control module can simulate the inertia and damping characteristics of a synchronous generator using a virtual synchronous machine control algorithm to generate corresponding control signals. This adjusts the on / off states of the internal switching devices of the converter, thereby controlling the converter's output amplitude and phase to achieve synchronous operation with the grid. During the control process, the matching control module continuously compares the acquired actual output current and voltage with the target values ​​required for synchronous operation, dynamically correcting the control signals to ensure that the converter's output electrical quantities remain stable within a reasonable range. Finally, through the independent control and data acquisition of each matching control module, the accurate actual output current and voltage for each of the n grid-connected converters are obtained, providing reliable feedback data for subsequent reactive power calculation and closed-loop control.

[0022] In this embodiment, each matching control module can also dynamically adjust the active power output of the corresponding grid-connected converter by simulating the frequency and active power droop characteristics of the synchronous generator and the inertial damping mechanism, combined with grid frequency feedback. Specifically, the matching control module first collects the grid frequency at the grid connection point in real time, compares it with the rated frequency, and calculates the frequency deviation. When the grid frequency is higher than the rated value, it indicates that the system has excess active power, and the module will reduce the active power command of the corresponding converter according to the preset droop coefficient. When the grid frequency is lower than the rated value, it indicates that the system has insufficient active power, and the module will increase the active power command according to the droop coefficient. Through this frequency and active power linkage, grid frequency support is achieved. At the same time, the module simulates the rotational inertia of the synchronous generator through virtual inertial control, slows down the rate of change of active power when the frequency changes abruptly, avoids frequency oscillation caused by power surges, and then suppresses the oscillation trend during frequency fluctuations through the damping control link, accelerating the frequency recovery to steady state. After generating the adjusted active power command, the matching control module transmits it to the converter's internal control unit. By adjusting the pulse width modulation strategy of the converter's switching devices, the conversion efficiency of DC-side energy to AC-side energy in the converter is changed, thereby precisely controlling the converter's active power output. Throughout the adjustment process, the module continuously collects the actual output current and voltage of the converter, calculates the actual active power and compares it with the command value, dynamically corrects the control signal, and ensures that the active power output stably tracks the adjusted command value while maintaining synchronous operation with the grid, thus achieving flexible adjustment of active power and stable control of system frequency.

[0023] S203: Determine the n actual reactive power outputs corresponding to the n grid-type converters based on the n actual output currents and the n actual output voltages.

[0024] In this embodiment, based on the actual output current and actual output voltage of each grid-type converter, the electrical parameters of each converter can be calculated using the reactive power calculation logic of the three-phase AC circuit. Specifically, the calculation can be performed using the effective voltage value, the effective current value, and the phase difference between the two. The actual reactive power of each of the n grid-type converters is calculated sequentially, and finally, n actual reactive power values ​​corresponding to the n grid-type converters are obtained.

[0025] S204: The reactive power control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs.

[0026] In this embodiment, the reactive power control module can calculate the difference between the actual reactive power output power and the corresponding preset reactive power output power for each grid-connected converter, thereby obtaining the reactive power deviation of each converter. Then, utilizing the strong coupling relationship between reactive power and voltage amplitude, the module processes each reactive power deviation through a proportional-integral adjustment algorithm, converting it into a corresponding voltage amplitude correction. At the same time, the reactive voltage droop characteristic is introduced to adapt to the grid operation pattern and avoid voltage oscillations when multiple converters are connected in parallel. Subsequently, each voltage amplitude correction is superimposed on a unified voltage reference, which is usually the rated voltage at the grid connection point, thereby generating a voltage reference signal that corresponds one-to-one with each grid-connected converter.

[0027] It should be explained that in this embodiment, the reactive power control module can serve as the core of the outer loop of the grid-type control. For each grid-type converter, the deviation between its actual reactive power output and the corresponding preset reactive power output is first calculated. Then, based on the voltage source characteristics of the grid-type control, and utilizing the strong coupling relationship between reactive power and voltage amplitude, a proportional-integral (PI) regulator performs closed-loop adjustment of the reactive power deviation. The proportional loop quickly outputs the adjustment amount according to the magnitude of the deviation, while the integral loop eliminates the steady-state deviation. Finally, the reactive power deviation is converted into a correction amount for the internal potential amplitude. Simultaneously, combined with the voltage support function of the outer loop of the grid-type control, this correction amount is applied to a unified voltage reference, forming a voltage reference signal specific to each converter. This process ensures that the actual reactive power output accurately tracks the preset value through PI regulation and guarantees the stability of the reference voltage based on the voltage source characteristics of the grid-type control, thereby ultimately determining n voltage reference signals corresponding one-to-one with the n grid-type converters. The objective function of the reactive power control module in adjusting the internal potential amplitude and providing voltage reference signals for the inner loop control satisfies the following formula:

[0028] in, It is a proportional-integral regulator for reactive power control loop. The reference reactive power output of the converter. This represents the actual reactive power output of the converter. It is a voltage reference signal. It is the d-axis voltage reference signal. The d-axis voltage reference signal is used in grid-connected converters. The voltage component corresponding to the d-axis mainly controls the amplitude of the converter's output voltage and is also related to the regulation of reactive power. By adjusting the d-axis voltage reference signal, the amplitude of the converter's internal potential can be directly changed, thereby accurately controlling the reactive power output. Usually, the d-axis voltage reference signal is set to 0 to synchronize the phase of the converter's output voltage with the grid, while also achieving decoupled control of active and reactive power to avoid mutual interference during power regulation.

[0029] S205: The self-interference rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents.

[0030] In this embodiment, please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of an active disturbance rejection virtual impedance control module provided in an embodiment of this application. The active disturbance rejection virtual impedance control module includes a tracking differentiator unit, an extended state observer unit, a nonlinear state error feedback unit, and a disturbance estimation compensation unit. In this embodiment, firstly, n capacity ratios corresponding to the n grid-type converters are obtained, and n preset virtual impedance values ​​corresponding to the n grid-type converters are determined based on the n capacity ratios. Then, the tracking differentiator unit determines n current change rate signals based on the n actual output currents. Next, the extended state observer unit determines n disturbance signals based on the n current change rate signals, the n actual output currents, and the n preset virtual impedance values. Then, the nonlinear state error feedback unit determines n voltage compensation amounts based on the n disturbance signals, the n actual output currents, and the n preset output currents. Finally, the disturbance estimation compensation unit determines the n voltage compensation signals based on the n voltage compensation amounts.

[0031] For example, n capacity ratios corresponding to the n grid-type converters are obtained, and n preset virtual impedance values ​​corresponding to the n grid-type converters are determined based on the n capacity ratios. Specifically, the capacity ratios between the n grid-type converters can be calculated by first obtaining their respective rated capacities, or by using preset capacity ratios. The capacity ratios reflect the proportional relationship of the power carrying capacity of each converter in the system. Based on this proportional relationship, preset virtual impedance values ​​are allocated. The core principle is that the larger the converter capacity, the smaller the preset virtual impedance value, and the smaller the capacity, the larger the preset virtual impedance value. This makes the virtual impedance ratio and the capacity ratio inversely matched. This design can ensure that each converter reasonably bears the reactive power of the system according to its capacity ratio and avoid reactive circulating current caused by impedance mismatch.

[0032] For example, the tracking differentiator unit determines n current change rate signals based on the n actual output currents. Specifically, the tracking differentiator unit processes the actual output current collected by each grid-type converter. This unit has signal smoothing and differentiation functions. It can first filter the high-frequency noise in the actual output current to obtain a stable current signal, and then perform time-domain differentiation on the stable current signal to accurately capture the characteristics of the current changing with time. Finally, it outputs a current change rate signal that reflects the dynamic change trend of its current for each converter, forming n current change rate signals corresponding to the n actual output currents.

[0033] For example, the extended state observer unit determines n disturbance signals based on the n current change rate signals, the n actual output currents, and the n preset virtual impedance values. Specifically, the extended state observer unit, through its internal nonlinear observation algorithm, can comprehensively analyze various internal and external disturbances such as line impedance differences, device parameter deviations, new energy output fluctuations, and grid voltage distortions as a total disturbance without relying on a precise mathematical model of the system. It accurately separates and identifies the disturbance factors affecting the operating state of each converter, and finally generates n disturbance signals corresponding one-to-one with the n grid-type converters.

[0034] For example, the nonlinear state error feedback unit determines n voltage compensation amounts based on the n disturbance signals, the n actual output currents, and the n preset output currents. Specifically, the nonlinear state error feedback unit first calculates the difference between the actual output current and the preset output current of each grid-type converter to obtain the current deviation. Then, it combines the corresponding disturbance signal estimated by the extended state observer unit and the preset virtual impedance value, and performs fusion processing on these signals through a nonlinear feedback algorithm. This algorithm can dynamically adjust the feedback strength according to the magnitude of the current deviation. When the deviation is large, the feedback effect is enhanced to quickly correct the deviation, and when the deviation is small, the feedback effect is weakened to avoid system oscillation. At the same time, it fully considers the amplitude and changing trend of the disturbance signal to generate a targeted voltage regulation amount that can both offset the disturbance effect and correct the current deviation, and finally forms n voltage compensation amounts corresponding one-to-one with the n grid-type converters.

[0035] For example, the disturbance estimation and compensation unit determines the n voltage compensation signals based on the n voltage compensation amounts. Specifically, the disturbance estimation and compensation unit, as the output stage of the active disturbance rejection virtual impedance control module, receives the n voltage compensation amounts generated by the nonlinear state error feedback unit. This unit first limits the amplitude of each voltage compensation amount according to the safety constraints of system operation, ensuring that the compensation amount does not exceed the maximum adjustment range of the converter output voltage and the device withstand voltage limit. Simultaneously, it performs phase calibration on the compensation amount to ensure that the phase of the compensation voltage matches the phase of the converter output voltage, avoiding new system oscillations caused by phase deviation. After the above optimization process, the n voltage compensation amounts are finally converted into n voltage compensation signals that can be directly input to the voltage-current dual-loop control module, achieving accurate cancellation of disturbances and effective suppression of circulating current.

[0036] It can be seen that, based on the capacity ratio reverse matching preset virtual impedance value, it can ensure that each converter reasonably allocates reactive power according to its own power carrying capacity, thereby avoiding reactive circulating current caused by impedance mismatch from the root. The tracking differentiator unit smooths and differentiates the actual output current, eliminating high-frequency noise interference and accurately capturing dynamic changes in current, providing reliable data support for disturbance estimation. The extended state observer unit can accurately identify various internal and external disturbances such as line impedance differences and device parameter deviations without relying on a precise system model, solving the problem of poor adaptability to disturbances in traditional control. The nonlinear state error feedback unit can quickly correct current deviations and avoid system oscillations by dynamically adjusting the feedback strength. At the same time, it generates targeted voltage compensation amounts in combination with disturbance signals, achieving synergy between deviation correction and disturbance cancellation. The disturbance estimation compensation unit limits the amplitude and calibrates the phase of the compensation amount, ensuring the safety and matching of voltage compensation and avoiding new system problems caused by improper compensation. The overall process, through the collaborative work of each unit, effectively reduces the circulating current value between converters, improves the system's adaptability to complex disturbances, ensures the voltage stability and operational reliability of the new energy grid-connected system, and achieves precise allocation and dynamic tracking of reactive power.

[0037] It should be noted that, in this embodiment, the voltage compensation signal can also be determined based on the active disturbance rejection virtual impedance algorithm. For details, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a block diagram of an active disturbance rejection virtual impedance control provided in an embodiment of this application. Figure 4 In this study, circulating current suppression and voltage support in a grid-connected converter parallel system are achieved through self-rejecting virtual impedance control. Specifically, a current feedback loop is introduced into the voltage control. The virtual impedance is determined based on the converter capacity ratio, and the voltage target value is corrected using the voltage drop across the virtual impedance of the output current. Simultaneously, an Extended State Observer (ESO) is designed to track the current state and estimate the total system disturbance. Combined with a linear state error feedback mechanism, voltage dips are dynamically compensated. Finally, by observing and compensating for voltage drops in real time, the output voltage of each converter is kept consistent. Specifically, when the system is operating normally, the grid output voltage tracks the grid-side voltage in real time. When circulating current occurs due to voltage differences, the external line impedance decreases, causing a significant voltage drop. The voltage change at the grid connection point is as follows:

[0038] in, This represents the change in voltage along the d-axis at the grid connection point. This represents the q-axis voltage change at the grid connection point. The d-axis voltage at the grid connection point when a fault occurs. This represents the q-axis voltage at the grid connection point when a fault occurs. For the target value of the d-axis voltage at the grid connection point, This represents the target q-axis voltage value at the grid connection point.

[0039] Virtual impedance essentially introduces a current feedback loop into voltage control. The voltage drop across the virtual impedance is used to continuously correct the target voltage value, improving the transient voltage. This provides voltage support when system faults occur or abnormal circulating currents arise, ensuring the current-sharing performance and safe, reliable operation of the parallel system. Virtual impedance satisfies the following formula:

[0040] in, For virtual impedance, For virtual resistance, For virtual inductance, is the complex frequency variable in the complex frequency domain.

[0041] In the dq coordinate system, The compensation for the voltage drop is:

[0042] The dq coordinate system includes the d-axis and the q-axis. For the d-axis output current of the converter, The d-axis output current change rate. For the q-axis output current of the converter, This represents the rate of change of the output current along the q-axis.

[0043] The core design of the active disturbance rejection virtual impedance algorithm is the design of the extended state observer. The extended state observer tracks state information and estimates system disturbances based on the system output and the input of the controlled object. This is to achieve the desired output current for the grid-type converter. For real-time tracking and estimation of system disturbances, the extended state observer in this scheme satisfies the following formula:

[0044] in, , and Both are derivatives of the state estimators. , and All are gain coefficients. and All are state estimators. The total disturbance consists of system model error and external disturbance. and All of these are model parameters. and All are parameters of a power function. The length of the linear segment interval, , All are power functions with a linear segment near the origin, which can prevent high-frequency flutter. Power functions with a linear segment near the origin satisfy the following formula:

[0045] in, It is a parameter of a power function, and its value is usually between 0 and 1.

[0046] Nonlinear active disturbance rejection control (ADRC) dynamically compensates for disturbances. It estimates the total system disturbance in real time using its extended state observer and directly feeds this disturbance forward into the control input, thus achieving active disturbance rejection calculation error feedback control. Its control form satisfies the following formula:

[0047] in, Refers to state error, For tracking output State estimator This refers to the initial control quantity of the system.

[0048] The total disturbance term satisfies the following formula:

[0049]

[0050] in, This represents the total disturbance term along the d-axis. This represents the total disturbance term on the q-axis. It can be a nonlinear disturbance. Let d be the desired current value along the d-axis. This represents the d-axis gain coefficient in active disturbance rejection control. This represents the q-axis gain coefficient in active disturbance rejection control. The control voltage for the d-axis. This is the control voltage for the q-axis.

[0051] Taking the d-axis as an example, when the total disturbance is treated as the extended state variable of the system, the system can be restated as follows:

[0052] in, The disturbance term is the d-axis. The output of the system refers to the output quantity. Based on the above formula, taking the d-axis as an example, the extended state observer is designed as follows:

[0053] in, The time derivative of the d-axis current estimate. The time derivative of the total d-axis disturbance estimate. The output variable for the d-axis is the state estimate. This is the estimated total disturbance along the d-axis. and The gain is the output error. and This is a non-linear factor.

[0054] Under most operating conditions, linear state error feedback has good disturbance suppression capability. To simplify the control structure, this implementation adopts a linear state error feedback mechanism, which effectively suppresses the circulating current of the system by dynamically compensating for voltage dips. The linear state error feedback form adopted is as follows:

[0055] in, The state error is the d-axis. This is the current reference value for the d-axis. The current given on the d-axis, The control quantity is the one that has not undergone dynamic compensation by the extended state observer. This is the estimated total d-axis perturbation obtained from the extended state observer. This represents the d-axis gain coefficient of the active disturbance rejection control. An extended state observer is used to estimate and feedforward compensate for the equivalent voltage drop caused by line impedance differences and coupling effects in real time, ensuring consistent output voltage across all converters. By monitoring and compensating for the system's voltage drop in real time, circulating current is suppressed.

[0056] It can be seen that the advantages of doing this are that it can improve the transient voltage support capability by using the current feedback of virtual impedance, and can accurately respond to disturbances such as line impedance differences and device deviations by expanding the state observer. It can actively resist disturbances without relying on the accurate system model. At the same time, the linear state error feedback simplifies the control structure, can effectively suppress abnormal circulating current, and ensure the current sharing performance and safe and reliable operation of the parallel system, thereby improving the stability of the new energy grid-connected system under fault or disturbance conditions.

[0057] S206: The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages.

[0058] In this embodiment, the n target output voltages are all equal, which reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0059] For example, the voltage and current dual-loop control module determines n voltage modulation signals based on the n voltage reference signals and the n voltage compensation signals. Specifically, the voltage reference signals are voltage control benchmarks generated by the reactive power control module, corresponding one-to-one with the n grid-connected converters. They are obtained through proportional-integral regulation and voltage amplitude correction based on the deviation between the grid-connected reactive power command and the actual reactive power output. Their core function is to clarify the target amplitude and phase of the output voltage of each converter, serving as the fundamental guiding signal for converter voltage control, ensuring that the converter output voltage matches the grid operation requirements and supports precise reactive power allocation. The voltage compensation signals are voltage correction signals output by the self-disruption virtual impedance control module, tailored to each converter. They are based on the actual output current, The generation of current change rate and system disturbance estimation can specifically offset internal and external interference such as line impedance differences and device parameter deviations, while suppressing abnormal circulating currents. Its core function is to dynamically correct the voltage reference signal, thereby improving the voltage stability and anti-interference capability of the converter under disturbance or fault conditions. The voltage modulation signal is the control signal ultimately generated by the voltage and current dual-loop control module, which can directly drive the converter's switching devices. By fusing the voltage reference signal and the voltage compensation signal, it transforms the voltage control target into the duty cycle command required for pulse width modulation. Its core function is to control the on and off durations of the switching devices inside the converter, thereby accurately adjusting the actual output voltage of the converter to match the target value. It is a key execution signal connecting the control algorithm and the converter hardware action.

[0060] For example, the voltage-current dual-loop control module adjusts the n actual output voltages based on the n voltage modulation signals, thereby adjusting the n actual output voltages to n target output voltages. Specifically, the voltage-current dual-loop control module transmits the generated n voltage modulation signals to the corresponding grid-type converters. Through these signals, the module controls the working state of the pulse width modulation unit inside the converter, dynamically adjusting the on and off durations of the switching devices, thereby changing the amplitude and phase of the converter output voltage. At the same time, the module collects the actual output voltage of each converter in real time, continuously compares it with the preset target output voltage, and dynamically corrects the duty cycle of the voltage modulation signal based on the deviation between the two, forming a closed-loop regulation mechanism. Ultimately, the actual output voltage of each converter is accurately tracked and adjusted to the corresponding target output voltage, ensuring the consistency and stability of the output voltage when multiple converters are connected in parallel.

[0061] As can be seen, the matching control module first accurately collects the actual output current and voltage of each converter, providing a reliable feedback basis for subsequent control. Then, the reactive power control module generates a voltage reference signal based on the deviation between the actual and preset reactive power output, ensuring that each converter accurately undertakes reactive power according to the grid connection command and meets the reactive power demand of the grid. The active disturbance rejection virtual impedance control module generates a targeted voltage compensation signal based on the actual output current, which can actively offset internal and external disturbances such as line impedance differences and device parameter deviations, effectively suppressing the generation of abnormal circulating current. Finally, the voltage and current dual-loop control module integrates the voltage reference signal and the compensation signal, and uniformly adjusts the actual output voltage of all converters to the same target output voltage, reducing the voltage difference between converters from the root, reducing the circulating current value, and improving the voltage support capability of the system under disturbance or fault conditions. Ultimately, this ensures the safe and reliable operation of the new energy grid-connected system, optimizes current sharing performance, and ensures stable grid connection.

[0062] It should be noted that, in this embodiment, a virtual impedance matching control method for grid-connected renewable energy systems is also provided to improve the stability of the renewable energy grid-connected system operation. Please refer to [link to relevant documentation]. Figure 5 , Figure 5 This is a control block diagram of a grid-connected new energy system with virtual impedance matching control provided in an embodiment of this application. Figure 5 The main components include matching control, current decoupling control, voltage feedback control, virtual impedance control, and reactive power control. Photovoltaic panels serve as the DC power source for grid-connected renewable energy systems with virtual impedance matching control. The input power of the photovoltaic panel. The active power input to the grid-side converter. This represents the DC capacitor voltage of the photovoltaic system. The CC is the DC-side capacitor for photovoltaic power generation, and the GCS is the grid-side converter. This refers to the three-phase AC current output by the converter. This refers to the three-phase AC voltage output from the converter. It is the three-phase voltage output by the converter. For filtering inductors, For line resistance, Here, θ represents the line inductance, abc / dq is the three-phase coordinate transformation, θ is the phase of the grid-side converter modulation voltage, and PWM is Pulse Width Modulation (PWM). This is the voltage modulation signal output from the grid-side converter. The modulated wave along the d-axis. The modulated wave along the q-axis It is a current loop proportional-integral controller. It is the cross-coupling compensation term for the dq axis. It is a voltage loop proportional-integral controller. It is a reactive power proportional-integral controller. The rated angular velocity of the power grid. It is the d-axis voltage reference signal. It is the q-axis voltage reference signal. For the d-axis output current of the converter, For the q-axis output current of the converter, This is the current reference value for the d-axis. This is the current reference value for the q-axis. This represents the actual reactive power output. This is a reference value for reactive power. Figure 5 This paper demonstrates the working logic of a grid-connected renewable energy system using virtual impedance matching control. First, the electrical energy output from the photovoltaic unit is regulated by capacitors and then input to the grid-connected converter. The converter uses an angle signal generated by matching control to convert the output current and voltage from a three-phase stationary coordinate system to a dq rotating coordinate system. Then, a dual-loop control system for current and voltage is constructed using a virtual impedance loop. The current loop generates a voltage reference based on the voltage drop characteristics of the virtual impedance, and the voltage loop further corrects this to obtain the dq-axis voltage command. Simultaneously, a reactive power control loop is introduced to adjust the d-axis voltage reference based on reactive power deviation. Finally, the voltage command is converted into a three-phase modulation signal to drive the converter's PWM unit, ensuring that the converter's output voltage matches the grid characteristics. This design achieves the voltage source characteristics of the grid-connected converter through virtual impedance matching, actively supporting the grid voltage and participating in reactive power regulation, while also suppressing grid-connected circulating current, ensuring stable grid connection of the renewable energy system.

[0063] It can be seen that by using the virtual impedance link to simulate the impedance characteristics of the voltage source, the converter can present a stable grid-type voltage source output. This not only enhances the active support capability for grid voltage, but also suppresses grid-connected circulating current through impedance matching, avoiding power distribution imbalance when multiple devices are connected in parallel. At the same time, the dual-loop control of the current loop and voltage loop combined with reactive power regulation can accurately track reactive power commands and quickly correct voltage and current deviations, improving the power quality of new energy grid connection. This not only strengthens the system's anti-interference capability under grid disturbances, but also improves the stability and reliability of new energy grid connection, taking into account both grid-connected power quality and system operation safety.

[0064] It should be noted that, in this embodiment, the circulating current value between the n grid-connected converters before the n actual output voltages are adjusted to n target output voltages by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals, is also determined to obtain a first circulating current value. Furthermore, the circulating current value between the n grid-connected converters after the n actual output voltages are adjusted to n target output voltages by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals, is determined to obtain a second circulating current value. Then, based on the first circulating current value and the second circulating current value, the stability improvement value corresponding to the new energy grid-connected system is determined to obtain the target stability improvement value. Specifically, before the voltage and current dual-loop control module adjusts the actual output voltage of the n grid-connected converters based on n voltage reference signals and n voltage compensation signals, it first detects the magnitude of the circulating current among the n grid-connected converters due to factors such as output voltage differences and line impedance mismatch to obtain the first circulating current value. When the voltage and current dual-loop control module adjusts the actual output voltage of the n grid-connected converters until all actual output voltages are precisely adjusted to the same n target output voltages, it then detects or calculates the magnitude of the circulating current among the n grid-connected converters to obtain the second circulating current value. Then, through a preset quantitative evaluation algorithm, it quantitatively analyzes the stability changes of the new energy grid-connected system before and after voltage adjustment, and finally obtains a target stability improvement value that can intuitively reflect the improvement in system stability.

[0065] In this embodiment, please refer to Figure 6 , Figure 6 This is a comparison diagram of the circulating current state before and after adjusting the actual output voltage of n grid-type converters, provided by an embodiment of this application. The horizontal axis of the circulating current before and after adjusting the actual output voltage of n grid-type converters is time, and the vertical axis is the magnitude of the circulating current. The circulating current before adjusting the actual output voltage of n grid-type converters fluctuates slightly around 0, but the fluctuation range is relatively wide, indicating that there is a certain circulating current between the converters due to factors such as output voltage difference and impedance mismatch. The fluctuation range of the circulating current after adjusting the actual output voltage of n grid-type converters is significantly narrowed and closer to 0, indicating that after adjusting the actual output voltage to the target output voltage through voltage and current dual-loop control, the voltage difference between the converters is greatly reduced, and the circulating current is effectively suppressed.

[0066] It should be noted that, in this embodiment, for example, if the second circulating current value is greater than the first circulating current value, the target stability improvement value is determined to be 0. Specifically, when the adjusted second circulating current value is greater than the first circulating current value before adjustment, it indicates that the measure of adjusting the output voltage through voltage and current dual-loop control not only fails to reduce the circulating current, but also exacerbates the circulating current. The system stability is not improved and may even decrease. Therefore, the target stability improvement value is determined to be 0, which means that this control measure has no positive improvement effect on system stability.

[0067] For example, if the first circulating current value is greater than the second circulating current value, the circulating current difference between the first circulating current value and the second circulating current value is determined, and the target stability improvement value is determined based on the circulating current difference. Specifically, when the first circulating current value before adjustment is greater than the second circulating current value after adjustment, it indicates that the measure of adjusting the output voltage has effectively reduced the circulating current between the converters. At this time, it is necessary to calculate the numerical difference between the first circulating current value and the second circulating current value, and then determine the degree of circulating current suppression based on this circulating current difference.

[0068] When determining the target stability improvement value based on the circulation difference, for example, the stability improvement value corresponding to the circulation difference is determined to obtain a reference stability improvement value. Specifically, it can be a preset mapping relationship between the circulation difference and the stability improvement value. Based on this mapping relationship, the stability improvement value corresponding to the circulation difference can be determined to obtain a reference stability improvement value.

[0069] For example, the method involves obtaining the new energy output fluctuation rate of the grid-connected new energy system after the n actual output voltages are adjusted to n target output voltages by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals. Specifically, the reference stability improvement value is calculated based on the circulating current difference, reflecting the steady-state improvement effect under ideal operating conditions. However, in reality, the faster the output fluctuation rate, the more severe the power imbalance between converters caused by power surges, which will quickly break the original output voltage equilibrium state, leading to circulating current rebound. At the same time, the disturbance estimation accuracy of the active disturbance rejection control and the dynamic response of the voltage-current dual-loop will decrease because they cannot keep up with the disturbance rhythm, causing the actual effects of the scheme such as circulating current suppression and voltage stability to deviate from the ideal expectation, and the stability improvement is weakened. Therefore, it is necessary to obtain the new energy output fluctuation rate of the grid-connected new energy system after the n actual output voltages are adjusted to n target output voltages by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals.

[0070] For example, an adjustment parameter corresponding to the power output fluctuation rate of the new energy source is determined. Specifically, it can be a preset mapping relationship between the power output fluctuation rate of the new energy source and the adjustment parameter. Based on this mapping relationship, the adjustment parameter corresponding to the power output fluctuation rate of the new energy source can be determined.

[0071] For example, the reference stability improvement value is adjusted based on the adjustment parameters to obtain the target stability improvement value. Specifically, the target stability improvement value is calculated according to the following formula: Target stability improvement value = Reference stability improvement value × (1 + Adjustment parameter); Based on the above formula, the reference stability improvement value can be adjusted according to the adjustment parameters to obtain the target stability improvement value.

[0072] It should be explained that the degree of improvement in the stability of the new energy grid-connected system can also be evaluated based on the grid connection point voltage, grid connection point voltage amplitude, grid connection point current, and grid connection point current amplitude corresponding to each grid-type converter. The degree of improvement in the stability of the new energy grid-connected system can also be verified through simulation models. The specific method for determining the degree of improvement in the stability of the new energy grid-connected system is not limited here.

[0073] As can be seen, by first comparing the circulation values ​​before and after the adjustment, we can intuitively judge whether the control measures are effective in suppressing the circulation, thus avoiding the misjudgment of ineffective control measures as effective. Then, we combine the stability improvement based on the circulation difference quantification to ensure the objectivity of the assessment. Finally, we introduce the adjustment parameter corresponding to the power output fluctuation rate of the new energy source to correct the assessment results. This can take into account the power output fluctuation interference in the actual operation of the system, making the calculation of the stability improvement value more in line with the real working conditions and ensuring the accuracy of the assessment.

[0074] In summary, implementing the embodiments of the present invention has the following beneficial effects: As can be seen, the multi-grid converter control method based on self-rejection virtual impedance described in this embodiment of the invention is applied to a new energy grid-connected system. The new energy grid-connected system includes n grid-connected converters, n matching control modules, a reactive power control module, a voltage-current dual-loop control module, and a self-rejection virtual impedance control module. Each grid-connected converter corresponds to one matching control module, and n is a positive integer. First, the grid-connected reactive power command is obtained, which includes n preset reactive power outputs corresponding to the n grid-connected converters. Each grid-connected converter corresponds to one preset reactive power output. Then, the actual output current and actual output voltage of each of the n grid-connected converters are controlled by the n matching control modules to obtain n actual output currents and n actual output voltages. Next, based on the n actual output currents and n actual output voltages, the n actual reactive power outputs corresponding to the n grid-connected converters are determined. Then, the reactive power control module... Based on the n actual reactive power outputs and the n preset reactive power outputs, n voltage reference signals are determined. Then, the self-interference rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. Finally, the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages, wherein the n target output voltages are all equal. This reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0075] Please see Figure 7 , Figure 7 This is a schematic diagram of a multi-grid converter control device based on active disturbance rejection virtual impedance provided in this application. The multi-grid converter control device 700 based on active disturbance rejection virtual impedance is applied to a new energy grid-connected system. The new energy grid-connected system includes n grid-connected converters, n matching control modules, reactive power control modules, voltage and current dual-loop control modules, and active disturbance rejection virtual impedance control modules. Each grid-connected converter corresponds to one matching control module, where n is a positive integer. The multi-grid converter control device 700 based on active disturbance rejection virtual impedance includes an acquisition unit 701 and a processing unit 702. The acquisition unit 701 is used to acquire grid-connected reactive power instructions; the grid-connected reactive power instructions include n preset reactive power outputs corresponding to the n grid-type converters, and each grid-type converter corresponds to one preset reactive power output. The processing unit 702 is used to control the actual output current and actual output voltage of each of the n grid-type converters through the n matching control modules, so as to obtain n actual output currents and n actual output voltages. The n actual reactive power outputs corresponding to the n grid-type converters are determined based on the n actual output currents and the n actual output voltages. The reactive power control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs. The self-disruption rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; the n target output voltages are all equal, which reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0076] In some possible implementations, the active disturbance rejection virtual impedance control module includes a tracking differentiator unit, an extended state observer unit, a nonlinear state error feedback unit, and a disturbance estimation compensation unit; the processing unit 702, which determines n voltage compensation signals based on the n actual output currents through the active disturbance rejection virtual impedance control module, is specifically used for: Obtain the n capacity ratios corresponding to the n grid-type converters, and determine the n preset virtual impedance values ​​corresponding to the n grid-type converters based on the n capacity ratios; The tracking differentiator unit determines n current change rate signals based on the n actual output currents; The extended state observer unit determines n disturbance signals based on the n current change rate signals, the n actual output currents, and the n preset virtual impedance values. The nonlinear state error feedback unit determines n voltage compensation values ​​based on the n disturbance signals, the n actual output currents, and the n preset output currents. The disturbance estimation and compensation unit determines the n voltage compensation signals based on the n voltage compensation amounts.

[0077] In some possible implementations, in adjusting the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals by the voltage-current dual-loop control module, so that the n actual output voltages are adjusted to n target output voltages, the processing unit 702 is specifically used for: The voltage-current dual-loop control module determines n voltage modulation signals based on the n voltage reference signals and the n voltage compensation signals; The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage modulation signals, so that the n actual output voltages are adjusted to n target output voltages.

[0078] In some possible implementations, the processing unit 702 is further specifically used for: The circulating current value among the n grid-type converters is determined by adjusting the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals through the voltage and current dual-loop control module, so that the n actual output voltages are adjusted to the n target output voltages, and the first circulating current value is obtained. The second circulating current value is obtained by determining the circulating current value among the n grid-type converters after the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals so that the n actual output voltages are adjusted to the n target output voltages. Based on the first circulation value and the second circulation value, the stability improvement value corresponding to the new energy grid-connected system is determined, and the target stability improvement value is obtained.

[0079] In some possible implementations, in determining the stability improvement value corresponding to the new energy grid-connected system based on the first circulating current value and the second circulating current value, and obtaining the target stability improvement value, the processing unit 702 is specifically used for: If the second circulation value is greater than the first circulation value, the target stability improvement value is determined to be 0; If the first circulation value is greater than the second circulation value, then the circulation difference between the first circulation value and the second circulation value is determined; The degree of improvement in the target stability is determined based on the circulation difference.

[0080] In some possible implementations, in determining the target stability improvement value based on the circulation difference, the processing unit 702 is specifically used for: Determine the stability improvement value corresponding to the circulation difference to obtain a reference stability improvement value; The new energy output fluctuation rate of the new energy grid-connected system is obtained after the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; Determine the adjustment parameters corresponding to the power output fluctuation rate of the new energy source; The reference stability improvement value is adjusted based on the adjustment parameters to obtain the target stability improvement value.

[0081] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. For example... Figure 8 As shown, the electronic device 800 includes a transceiver 801, a processor 802, and a memory 803. They are connected via a bus 804. The memory 803 stores computer programs and data, and the transceiver 801 can transmit data stored in the memory 803 to the processor 802. The electronic device 800 is applied to a new energy grid-connected system, which includes n grid-connected converters, n matching control modules, a reactive power control module, a voltage and current dual-loop control module, and a self-interference rejection virtual impedance control module; each grid-connected converter corresponds to one matching control module, and n is a positive integer; the program includes instructions for performing the following steps: Obtain grid-connected reactive power instructions; the grid-connected reactive power instructions include n preset reactive power outputs corresponding to the n grid-type converters, and each grid-type converter corresponds to one preset reactive power output; By controlling the actual output current and actual output voltage of each of the n grid-type converters through the n matching control modules, n actual output currents and n actual output voltages are obtained. The n actual reactive power outputs corresponding to the n grid-type converters are determined based on the n actual output currents and the n actual output voltages. The reactive power control module determines n voltage reference signals based on the n actual reactive power outputs and the n preset reactive power outputs. The self-disruption rejection virtual impedance control module determines n voltage compensation signals based on the n actual output currents. The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; the n target output voltages are all equal, which reduces the circulating current value among the n grid-connected converters and improves the stability of the new energy grid-connected system.

[0082] In some possible implementations, the active disturbance rejection virtual impedance control module includes a tracking differentiator unit, an extended state observer unit, a nonlinear state error feedback unit, and a disturbance estimation compensation unit; regarding the determination of n voltage compensation signals based on the n actual output currents by the active disturbance rejection virtual impedance control module, the above procedure includes instructions for performing the following steps: Obtain the n capacity ratios corresponding to the n grid-type converters, and determine the n preset virtual impedance values ​​corresponding to the n grid-type converters based on the n capacity ratios; The tracking differentiator unit determines n current change rate signals based on the n actual output currents; The extended state observer unit determines n disturbance signals based on the n current change rate signals, the n actual output currents, and the n preset virtual impedance values. The nonlinear state error feedback unit determines n voltage compensation values ​​based on the n disturbance signals, the n actual output currents, and the n preset output currents. The disturbance estimation and compensation unit determines the n voltage compensation signals based on the n voltage compensation amounts.

[0083] In some possible implementations, in adjusting the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals by the voltage-current dual-loop control module, so that the n actual output voltages are adjusted to n target output voltages, the above procedure includes instructions for performing the following steps: The voltage-current dual-loop control module determines n voltage modulation signals based on the n voltage reference signals and the n voltage compensation signals; The voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage modulation signals, so that the n actual output voltages are adjusted to n target output voltages.

[0084] In some possible implementations, the above procedure includes instructions for performing the following steps: The circulating current value among the n grid-type converters is determined by adjusting the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals through the voltage and current dual-loop control module, so that the n actual output voltages are adjusted to the n target output voltages, and the first circulating current value is obtained. The second circulating current value is obtained by determining the circulating current value among the n grid-type converters after the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals so that the n actual output voltages are adjusted to the n target output voltages. Based on the first circulation value and the second circulation value, the stability improvement value corresponding to the new energy grid-connected system is determined, and the target stability improvement value is obtained.

[0085] In some possible implementations, in determining the stability improvement value corresponding to the new energy grid-connected system based on the first circulating current value and the second circulating current value, and obtaining the target stability improvement value, the above procedure includes instructions for performing the following steps: If the second circulation value is greater than the first circulation value, the target stability improvement value is determined to be 0; If the first circulation value is greater than the second circulation value, then the circulation difference between the first circulation value and the second circulation value is determined; The degree of improvement in the target stability is determined based on the circulation difference.

[0086] In some possible implementations, the above procedure includes instructions for performing the following steps in determining the target stability improvement value based on the circulation difference: Determine the stability improvement value corresponding to the circulation difference to obtain a reference stability improvement value; The new energy output fluctuation rate of the new energy grid-connected system is obtained after the voltage and current dual-loop control module adjusts the n actual output voltages based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to n target output voltages; Determine the adjustment parameters corresponding to the power output fluctuation rate of the new energy source; The reference stability improvement value is adjusted based on the adjustment parameters to obtain the target stability improvement value.

[0087] It should be understood that the electronic devices mentioned in this application may include smartphones (such as Android phones, iOS phones, Windows Phones, etc.), tablets, PDAs, laptops, mobile internet devices (MIDs) or wearable devices, servers, edge computing nodes, etc. The above-mentioned electronic devices are merely examples and not exhaustive, and include, but are not limited to, the electronic devices described above.

[0088] This application also provides a computer-readable storage medium storing a computer program that is executed by a processor to implement some or all of the steps of any of the methods described in the above method embodiments.

[0089] This application also provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program operable to cause a computer to perform some or all of the steps of any of the methods described in the above method embodiments.

[0090] It should be noted that, for the sake of simplicity, the aforementioned methods are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are optional, and the actions and modules involved are not necessarily essential to this application.

[0091] In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0092] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0093] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0094] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software program module.

[0095] If the integrated unit is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0096] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage device, which may include: flash drive, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0097] The embodiments of this application have been described in detail above. Specific examples have been used in this embodiment to illustrate the principles and implementation methods of this application. The description of the embodiments above is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A multi-construct network type converter control method based on a virtual impedance of a disturbance rejection, characterized in that, The multi-constructive network type converter control method based on the active disturbance rejection virtual impedance is applied to a new energy grid-connected system, and the new energy grid-connected system comprises n constructive network type converters, n matching control modules, a reactive power control module, a voltage and current double-loop control module and an active disturbance rejection virtual impedance control module. Each constructive network type converter corresponds to a matching control module, and n is a positive integer; the multi-constructive network type converter control method based on the active disturbance rejection virtual impedance comprises the following steps: An active disturbance rejection virtual impedance control module is obtained, and n capacity ratios corresponding to the n constructive network type converters are obtained; n current change rate signals are determined based on the n actual output currents by using the tracking differentiator unit; n disturbance signals are determined based on the n current change rate signals, the n actual output currents and n preset virtual impedance values by using the extended state observer unit; n voltage compensation amounts are determined based on the n disturbance signals, the n actual output currents and n preset output currents by using the nonlinear state error feedback unit; and the n voltage compensation signals are determined based on the n voltage compensation amounts by using the disturbance estimation compensation unit. The n actual output currents and the n actual output voltages are obtained by controlling the actual output current and the actual output voltage corresponding to each of the n constructive network type converters through the n matching control modules. The n actual reactive output powers corresponding to the n constructive network type converters are determined based on the n actual output currents and the n actual output voltages. The n voltage reference signals are determined based on the n actual reactive output powers and the n preset reactive output powers by using the reactive power control module. The n voltage compensation signals are determined based on the n actual output currents by using the active disturbance rejection virtual impedance control module. The n actual output voltages are adjusted to n target output voltages based on the n voltage reference signals and the n voltage compensation signals by using the voltage and current double-loop control module; the n target output voltages are all equal, so that the loop current value between the n constructive network type converters is reduced, and the stability of the new energy grid-connected system is improved.

2. The method of claim 1, wherein, The active disturbance rejection virtual impedance control module comprises a tracking differentiator unit, an extended state observer unit, a nonlinear state error feedback unit and a disturbance estimation compensation unit. The n voltage compensation signals are determined based on the n actual output currents by using the active disturbance rejection virtual impedance control module, and the method comprises the following steps: The n capacity ratios corresponding to the n constructive network type converters are obtained, and the n preset virtual impedance values corresponding to the n constructive network type converters are determined based on the n capacity ratios. The n current change rate signals are determined based on the n actual output currents by using the tracking differentiator unit. The n disturbance signals are determined based on the n current change rate signals, the n actual output currents and the n preset virtual impedance values by using the extended state observer unit. The n voltage compensation amounts are determined based on the n disturbance signals, the n actual output currents and n preset output currents by using the nonlinear state error feedback unit. The n voltage compensation signals are determined based on the n voltage compensation amounts by using the disturbance estimation compensation unit.

3. The method of claim 2, wherein, The n actual output voltages are adjusted to n target output voltages based on the n voltage reference signals and the n voltage compensation signals by using the voltage and current double-loop control module, and the method comprises the following steps: determining, by the voltage-current dual-loop control module, n voltage modulation signals based on the n voltage reference signals and the n voltage compensation signals; adjusting, by the voltage-current dual-loop control module, the n actual output voltages based on the n voltage modulation signals, so that the n actual output voltages are adjusted to be n target output voltages.

4. The method according to any one of claims 1 to 3, characterized in that, The method further comprises: determining a first circulating current value between the n grid-connected type converters before the n actual output voltages are adjusted by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to be n target output voltages; determining a second circulating current value between the n grid-connected type converters after the n actual output voltages are adjusted by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to be n target output voltages; determining a target stability improvement degree value corresponding to the new energy grid-connected system based on the first circulating current value and the second circulating current value.

5. The method of claim 4, wherein, The determination of the target stability improvement degree value corresponding to the new energy grid-connected system based on the first circulating current value and the second circulating current value comprises: if the second circulating current value is greater than the first circulating current value, determining that the target stability improvement degree value is 0; if the first circulating current value is greater than the second circulating current value, determining a circulating current difference value between the first circulating current value and the second circulating current value; determining the target stability improvement degree value based on the circulating current difference value.

6. The method of claim 5, wherein, The determination of the target stability improvement degree value based on the circulating current difference value comprises: determining a reference stability improvement degree value corresponding to the circulating current difference value; obtaining a new energy output fluctuation rate corresponding to the new energy grid-connected system after the n actual output voltages are adjusted by the voltage-current dual-loop control module based on the n voltage reference signals and the n voltage compensation signals, so that the n actual output voltages are adjusted to be n target output voltages; determining an adjustment parameter corresponding to the new energy output fluctuation rate; adjusting the reference stability improvement degree value based on the adjustment parameter to obtain the target stability improvement degree value.

7. A multi-construct network type converter control device based on a virtual impedance of a disturbance rejection, characterized by, The self-disturbance rejection virtual impedance-based multi-grid-connected type converter control device is applied to a new energy grid-connected system, and the new energy grid-connected system comprises n grid-connected type converters, n matching control modules, a reactive power control module, a voltage-current dual-loop control module, and a self-disturbance rejection virtual impedance control module. Each grid-connected type converter corresponds to one matching control module, and n is a positive integer. The self-disturbance rejection virtual impedance-based multi-grid-connected type converter control device comprises an acquisition unit and a processing unit. The acquisition unit is configured to acquire a grid-connected reactive power instruction. The grid-connected reactive power instruction comprises n preset reactive output powers corresponding to the n grid-connected type converters, and each grid-connected type converter corresponds to one preset reactive output power. The processing unit is configured to control actual output currents and actual output voltages of each of the n grid-forming converters through the n matching control modules, to obtain n actual output currents and n actual output voltages. The n actual output currents and the n actual output voltages are used to determine n actual reactive output powers of the n grid-forming converters. The n actual reactive output powers and the n preset reactive output powers are used by the reactive power control module to determine n voltage reference signals. The n actual output currents are used by the active disturbance rejection virtual impedance control module to determine n voltage compensation signals. The n voltage reference signals and the n voltage compensation signals are used by the voltage and current double-loop control module to adjust the n actual output voltages, so that the n actual output voltages are adjusted to be n target output voltages; the n target output voltages are equal, so that a circulating current value between the n grid-forming converters is reduced, and stability of the new energy grid-connected system is improved.

8. An electronic device, comprising: A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method of any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, When the computer program product is run on the computer, the computer is caused to execute the method of any one of claims 1-6.

10. A computer program product, characterised in that, When the computer program product is run on the computer, the computer is caused to execute the method of any one of claims 1-6.

Images