Inertia introduction-based grid-following type grid-connected inverter control method and system

Abstract

The invention discloses a network following type grid-connected inverter control method and system based on inertia introduction, and the method comprises the steps: obtaining a first parameter of a target grid-connected point, and carrying out the first processing of the first parameter, and obtaining a second parameter; obtaining a difference value between the second parameter and the first given value, and obtaining a first voltage control component according to the difference value in combination with a preset current controller; and calculating a second voltage component according to the first voltage control component, and controlling the grid-connected inverter according to the second voltage component. On the basis of frequency response of a PLL (Phase Locked Loop), integration is carried out in combination with current component change of a control loop, a new voltage feed-forward structure is constructed for control of the GFL grid-connected inverter, inertia is introduced for control of the GFL grid-connected inverter, and broadband oscillation of the GFL grid-connected inverter under a weak power grid can be effectively suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy power generation, and in particular to a control method and system for a grid-connected inverter based on inertia introduction. Background Art

[0002] With the access of a large number of new energy power generation equipment, the proportion of synchronous power generation equipment in the power system has decreased, and the inertia of the system has decreased. In addition, as the transmission lines become longer, the system grid impedance increases and the grid strength weakens. New energy power generation equipment that adopts the grid following (GFL) control strategy lacks inertia and is prone to cause voltage fluctuations at the point of common coupling (PCC) of the grid, causing wideband oscillation problems and endangering the stable operation of the grid.

[0003] Existing research mainly improves the stability of GFL inverters under weak power grids by improving the multi-loop control structures such as the phase locked loop (PLL) and current loop of GFL inverters, but it also increases the complexity of the system control structure, making it difficult to apply in actual projects. Although the virtual synchronous generator (VSG) technology can provide inertia for grid-connected inverters, it cannot operate stably under strong power grids like other grid-connected inverters, and is not suitable for the strong power grid environment commonly found in actual projects.

[0004] Therefore, in order to solve the above problems, it is of great research significance to study a method to improve the partial control structure of the GFL grid-connected inverter, introduce inertia, and improve the adaptability of the GFL grid-connected inverter in a complex power grid environment, so as to suppress the wide-band oscillation of the grid-connected new energy power generation equipment. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a control method and system for a grid-connected inverter based on inertia introduction, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a control method for a grid-connected inverter based on inertia introduction, comprising:

[0010] Acquire a first parameter of a target grid connection point, and perform a first processing on the first parameter to obtain a second parameter;

[0011] Obtaining a difference between the second parameter and the first given value, and obtaining a first voltage control component according to the difference in combination with a preset current controller;

[0012] A second voltage component is calculated according to the first voltage control component, and grid-connected inverter control is performed according to the second voltage component.

[0013] As a preferred solution of the grid-connected inverter control method based on inertia introduction described in the present invention, the grid-connected inverter control according to the second voltage component includes:

[0014] Performing coordinate system transformation according to the second voltage component to obtain a first modulated wave signal;

[0015] Inputting the first modulation wave signal into a first modulation controller to obtain a first modulation waveform;

[0016] The grid-connected inverter is controlled according to the first modulation waveform.

[0017] As a preferred solution of the control method of the grid-connected inverter based on inertia introduction described in the present invention, the current controller includes:

[0018] The current controller is any controller whose input is the difference between the second parameter and the first given value, and whose output is the first voltage control component.

[0019] As a preferred solution of the grid-connected inverter control method based on inertia introduction described in the present invention, wherein: the calculation of the second voltage component according to the first voltage control component includes:

[0020] The second voltage component is calculated according to the first voltage control component in combination with a preset first voltage feedforward output component and a first decoupling component.

[0021] As a preferred solution of the control method of the grid-connected inverter based on inertia introduction described in the present invention, the first voltage feedforward output component includes:

[0022] Obtaining a frequency change of a phase-locked loop and comparing it with a d-axis current difference in the difference through proportional coefficient control;

[0023] The comparison result is integrated to obtain a first voltage feedforward output component.

[0024] As a preferred solution of the control method of the grid-connected inverter based on inertia introduction described in the present invention, wherein: the first parameter of the target grid-connected point is obtained including:

[0025] Collecting a first parameter of the target grid connection point through a preset sampling circuit;

[0026] The first parameters include three-phase current and three-phase voltage at the grid connection point.

[0027] As a preferred solution of the control method of the grid-connected inverter based on inertia introduction described in the present invention, wherein: the obtaining of the difference between the second parameter and the first given value includes:

[0028] The second parameter includes a current component and a voltage component;

[0029] A current component in the second parameter is obtained, and a difference is calculated between the current component in the second parameter and the first given value to obtain a difference between the second parameter and the first given value.

[0030] In a second aspect, the present invention provides a grid-connected inverter control system based on inertia introduction, comprising:

[0031] A parameter acquisition module, used for acquiring a first parameter of a target grid connection point, and performing a first processing on the first parameter to obtain a second parameter;

[0032] A component acquisition module, used to acquire a difference between a second parameter and a first given value, and acquire a first voltage control component according to the difference in combination with a preset current controller;

[0033] A control module is used to calculate a second voltage component according to the first voltage control component, and to control a grid-connected inverter according to the second voltage component.

[0034] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0035] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes a control method and system for a grid-connected inverter based on inertia introduction, obtains a first parameter of a target grid-connected point, performs a first processing on the first parameter, and obtains a second parameter; obtains the difference between the second parameter and the first given value, and obtains a first voltage control component based on the difference combined with a preset current controller; calculates a second voltage component based on the first voltage control component, and performs grid-connected inverter control based on the second voltage component. Based on the frequency response of the PLL, a new voltage feedforward structure is constructed for the control of the GFL grid-connected inverter, and inertia is introduced for the control of the GFL grid-connected inverter, which can effectively suppress the wide-band oscillation of the GFL grid-connected inverter under a weak power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0038] Figure 1 A method flow chart of a method and system for controlling a grid-connected inverter based on inertia introduction provided by an embodiment of the present invention;

[0039] Figure 2 A control block diagram of a grid-connected inverter with inertia provided by a control method and system for a grid-connected inverter based on inertia introduction according to an embodiment of the present invention;

[0040] Figure 3 A comparison diagram of grid connection point voltage simulation of a grid-connected inverter control method and system based on inertia introduction provided by an embodiment of the present invention with changing grid strength, (a) is a single-phase voltage simulation waveform using a traditional GFL grid-connected inverter control method, and (b) is a single-phase voltage simulation waveform using the method of the present invention;

[0041] Figure 4 A simulation comparison diagram of power output size of a grid-connected inverter control method and system based on inertia introduction provided by an embodiment of the present invention, which changes the strength of the power grid, (a) is the output power waveform of the traditional GFL grid-connected inverter control method, and (b) is the output power waveform of the method of the present invention. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0043] Example 1

[0044] Reference Figure 1-Figure 4 , which is the first embodiment of the present invention, and provides a control method and system for a grid-connected inverter based on inertia introduction, including:

[0045] There are some problems in the existing related technologies. For example, in a weak power grid environment, the stability of the GFL grid-connected inverter is insufficient, which easily causes voltage fluctuations and wide-band oscillation problems at the common coupling point.

[0046] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the inertia-based grid-connected inverter control method.

[0047] Figure 1 A method flow chart of a grid-connected inverter control method and system based on inertia introduction is shown, including:

[0048] S101, obtaining a first parameter of a target grid connection point, and performing a first processing on the first parameter to obtain a second parameter;

[0049] In the embodiment of the present application, obtaining the first parameter of the target grid connection point includes:

[0050] Collecting a first parameter of a target grid connection point through a preset sampling circuit;

[0051] The first parameter includes three-phase current and three-phase voltage at the grid connection point.

[0052] In an optional embodiment, the target grid-connected point is the grid-connected point of the grid-connected inverter, and the first parameter of the target grid-connected point is to achieve the final control of the grid-connected inverter, so the first parameter may include the three-phase current and the three-phase voltage at the grid-connected point. These parameters are the basis for controlling the grid-connected inverter, because they are directly related to whether the current and voltage output by the grid-connected inverter can be synchronized with the grid, and whether they can meet the stability and quality requirements of the grid.

[0053] In an optional embodiment, relevant technicians can select other first parameters to control the grid-connected inverter according to actual needs. The first parameter can also be other parameters related to grid synchronization, such as frequency, phase angle, etc.

[0054] In an optional embodiment, the first parameter may also be a parameter at other grid-connected points, such as current harmonic content, voltage harmonic content, etc. These parameters are equally important for evaluating the performance of the grid-connected inverter and the power quality of the power grid, and the grid-connected inverter can also be controlled based on these parameters.

[0055] In the embodiment of the present application, the sampling circuit collects the three-phase current i of the PCC. a 、i b 、i c And the three-phase voltage u a 、u b 、u c and the DC dq voltage components u are obtained through Park transformation. d 、u q and d q Current component i d 、i q ;

[0056] Specifically, the process of Park transformation is as follows: a 、i b 、i c And the three-phase voltage u a 、u b 、u c The DC dq voltage component u is calculated by the Park transformation matrix T(θ) d 、u q and the current component i d 、i q .

[0057] The Park transformation matrix T(θ) is expressed as:

[0058]

[0059] In the embodiment of the present application, the DC dq voltage component u d 、u q and the current component i d 、i q The calculation process is:

[0060]

[0061] It should be noted that obtaining the first parameter of the target grid connection point and performing the first processing on the first parameter to obtain the second parameter can more accurately reflect the real-time state of the grid connection point and provide more accurate input data for the subsequent control strategy. The dq voltage component and current component obtained by Park transformation can more conveniently implement the control algorithm because they are based on a synchronous rotating coordinate system, which helps to simplify the control model and improve the response speed and accuracy of the control.

[0062] S102, obtaining a difference between a second parameter and a first given value, and obtaining a first voltage control component according to the difference in combination with a preset current controller;

[0063] In the embodiment of the present application, obtaining the difference between the second parameter and the first given value includes:

[0064] The second parameter includes a current component and a voltage component;

[0065] The current component in the second parameter is obtained, and the difference between the current component in the second parameter and the first given value is calculated to obtain the difference between the second parameter and the first given value.

[0066] In an embodiment of the present application, the current controller includes:

[0067] The current controller is any controller whose input is the difference between the second parameter and the first given value, and whose output is the first voltage control component.

[0068] In an optional embodiment, the current controller is designed based on a control strategy, and the underlying control strategy of the current controller is to process the difference between the second parameter and the first given value to obtain the first voltage control component. The control strategy can be designed in a variety of ways, and the current controller is designed based on these control strategies;

[0069] In an optional embodiment, the control strategy can be designed using a variety of methods, for example, a proportional-integral (PI) control strategy, a proportional-differential (PD) control strategy, or a proportional-integral-differential (PID) control strategy, etc. These control strategies can dynamically adjust the output according to the difference between the second parameter and the first given value, so as to achieve the purpose of quickly responding to the control demand of the grid-connected inverter.

[0070] In an optional embodiment, the control strategy may also use a neural network, and by training the neural network model, it can learn and predict the dynamic changes of the current component and the voltage component, thereby achieving more precise control. The neural network controller may receive the difference between the second parameter and the first given value as input, and output a corresponding voltage control component to adapt to the rapid changes in grid conditions.

[0071] In an optional embodiment, the control strategy may also use a fuzzy logic control strategy. By defining fuzzy rules and membership functions, the fuzzy logic controller can handle uncertainty and nonlinear factors, thereby effectively controlling the difference between the second parameter and the first given value. The fuzzy controller outputs a corresponding voltage control component according to the input difference through fuzzification, reasoning and defuzzification processes to adapt to the rapid changes in grid conditions.

[0072] In the embodiment of the present application, the control strategy is designed using a proportional-integral (PI) control strategy, and a current controller based on the control strategy is established to achieve the acquisition of the first voltage control component;

[0073] In the embodiment of the present application, the current given value i dref 、i qref Compare with the sampled DC dq current component to obtain the control loop current deviation value Δi d , Δi q ; Input the control loop current deviation value into the current controller output to obtain the DC voltage control component v d 、v q .

[0074] Specifically, the current given value is the current given value when the DC side of the new energy three-phase grid-connected inverter is stable. When the active power output value of the grid-connected inverter is set to P ref , the reactive power output power is Q ref When the current given value i dref 、i qref It is expressed as:

[0075]

[0076] In the formula, u d The value of * is the effective value V1 of the grid voltage amplitude.

[0077] Furthermore, the current controller is a PI controller and its transfer function is expressed as G PI (s) = K p +K i / s, where K p is the proportionality coefficient, K i is the integral coefficient, the DC voltage control component v d 、v q It can be expressed as:

[0078]

[0079] It should be noted that obtaining the difference between the second parameter and the first given value, and obtaining the first voltage control component based on the difference combined with the preset current controller can quickly respond to the control requirements of the grid-connected inverter and adjust the output voltage in time to adapt to the real-time changes of the power grid. Through the dynamic adjustment of the current controller, the fluctuation of the grid connection point voltage can be effectively reduced and the stability of the grid-connected inverter can be improved. In addition, the use of the PI control strategy can simplify the controller design while ensuring the accuracy and speed of the control, which is crucial to maintaining the stable operation of the grid-connected inverter in a weak power grid environment.

[0080] S103, calculating a second voltage component according to the first voltage control component, and controlling the grid-connected inverter according to the second voltage component.

[0081] In the embodiment of the present application, calculating the second voltage component according to the first voltage control component includes:

[0082] The second voltage component is calculated according to the first voltage control component in combination with a preset first voltage feedforward output component and a first decoupling component.

[0083] In an optional embodiment, the calculation of the second voltage component according to the first voltage control component can be implemented by using a variety of control algorithms, for example, a proportional-integral (PI) control algorithm, a proportional-differential (PD) control algorithm, or a proportional-integral-differential (PID) control algorithm, etc. These algorithms can dynamically adjust the output according to the size of the first voltage control component to achieve the purpose of quickly responding to the control requirements of the grid-connected inverter.

[0084] In an optional embodiment, the control algorithm can also be designed using a neural network or machine learning, and by training the neural network model, it can learn and predict the dynamic changes of the voltage control component, thereby achieving more accurate control. The neural network controller can receive a first voltage control component as input and output a corresponding second voltage component to adapt to rapid changes in grid conditions.

[0085] In an optional embodiment, the control algorithm may also use a fuzzy logic control algorithm. By defining fuzzy rules and membership functions, the fuzzy logic controller can handle uncertainty and nonlinear factors, thereby effectively controlling the first voltage control component. The fuzzy controller outputs a corresponding second voltage component based on the input first voltage control component through fuzzification, reasoning and defuzzification processes to adapt to the rapid changes in grid conditions.

[0086] In the embodiment of the present application, a proportional-integral (PI) control algorithm is used for design;

[0087] In the embodiment of the present application, the first voltage feedforward output component includes:

[0088] Obtain the frequency change of the phase-locked loop and compare it with the d-axis current difference in the difference through proportional coefficient control;

[0089] The comparison result is integrated to obtain a first voltage feedforward output component.

[0090] In an optional embodiment, the first decoupling component includes: calculating a compensation amount required for decoupling according to an output current and a voltage of the grid-connected inverter to eliminate a cross-coupling effect in a current control loop.

[0091] In an optional embodiment, the calculation of the decoupling component can be implemented based on the mathematical model of the inverter through an appropriate algorithm. For example, a feedforward decoupling control strategy can be adopted, which can calculate a compensation amount based on the output current and voltage of the inverter, thereby offsetting the influence of cross-coupling during the control process.

[0092] In an embodiment of the present application, controlling the grid-connected inverter according to the second voltage component includes:

[0093] Perform coordinate system transformation according to the second voltage component to obtain a first modulated wave signal;

[0094] Inputting the first modulation wave signal into the first modulation controller to obtain a first modulation waveform;

[0095] The grid-connected inverter is controlled according to the first modulation waveform.

[0096] In the embodiment of the present application, the voltage control component v d 、v q The DC voltage component v of the modulation wave is obtained by comparing it with the voltage feedforward output component and the dq decoupling component based on the PLL frequency response. dref 、v qref ; Perform an inverse Park transform on the DC voltage component of the modulation wave to obtain the modulation wave signal m a , m b , m c (ie, the first modulation wave signal), and outputs a PWM waveform (ie, the first modulation waveform) through a PWM controller, thereby realizing control of the three-phase half-bridge inverter.

[0097] In an optional embodiment, relevant technicians may select other coordinate system transformation methods for processing, for example, Clarke transformation may be used instead of Park transformation, or other transformation methods may be selected according to actual application requirements to adapt to different control scenarios.

[0098] In an alternative embodiment, the voltage feed-forward output component based on the PLL frequency response is Figure 2 As shown in the dotted box, the frequency change of the PLL is collected Δω = vq G PLL_PI (s), and the d-axis current deviation Δi is controlled by the proportional coefficient d By comparison, and through the integration link, the voltage feedforward output component v is obtained d_axi .

[0099]

[0100] Where, T1 is the inertia coefficient of the present invention, Δω=vqG PI_PLL (s), where G PLL_PI (s) = K p_PLL +K i_PLL / s,K p_PLL , K i_PLL They are the proportional coefficient and integral coefficient of the PI controller in the PLL respectively.

[0101] In an optional embodiment, the dq decoupling process is as follows Figure 2 As shown, they are respectively represented as -i q L f ω and i d L f ω, then the DC voltage component v of the modulation wave dref 、v qref It can be expressed as:

[0102]

[0103] In the formula, K f =1 / (K pwm *V dc ) is the voltage feedforward proportional coefficient, K pwm is the PWM coefficient, V dc is the DC side voltage of the three-phase grid-connected inverter.

[0104] In an optional embodiment, a modulated wave signal m is generated. a , m b , m c The process can be expressed as:

[0105]

[0106] In an optional embodiment, the control process of the three-phase half-bridge inverter is implemented as follows: the duty cycle of the PWM signal is continuously adjusted according to the obtained modulation wave signal; the PWM signal changes the on-off time of the switch tube to adjust the inverter output voltage.

[0107] In the embodiment of the present application, the present application uses the size of the SCR to measure the strength of the power grid. The smaller the SCR, the weaker the power grid. A power grid with SCR<3 is considered a weak power grid.

[0108] In an optional embodiment, the strength of the power grid can be measured in other ways, for example, by measuring the short-circuit capacity of the power grid to evaluate the strength of the power grid. The larger the short-circuit capacity, the higher the strength of the power grid, and vice versa. In addition, the strength of the power grid can also be comprehensively evaluated by parameters such as the voltage stability and frequency stability of the power grid.

[0109] In an optional embodiment, when the strength of the power grid is weak, an enhanced control strategy may be used to ensure stable operation of the grid-connected inverter.

[0110] In an optional embodiment, the enhanced control strategy includes but is not limited to: adding a voltage feedforward control link to improve the response speed to grid voltage fluctuations; introducing virtual impedance control to reduce the impact of grid faults on the inverter; and adopting improved control algorithms, such as adaptive control or sliding mode control, to improve the robustness of the inverter under complex grid conditions.

[0111] In the embodiment of the present application, the calculation formula of SCR is:

[0112]

[0113] In the formula, S ac is the short-circuit capacity of the power system; P N is the capacity of new energy equipment connected to the power grid, in MVA; U N is the rated voltage of the grid-connected busbar; Z is the total impedance of the access system, which can be expressed as Z l To estimate; Z pu is the per unit impedance value.

[0114] In an alternative embodiment, the design is as follows Figure 2 The structure shown, wherein the grid-connected inverter includes a DC side energy storage capacitor, a three-phase half-bridge inverter circuit, an LC filter circuit, a sampling circuit, a phase-locked loop controller, a control loop, and a PWM generator. The DC side energy storage capacitor enables the DC side voltage of the three-phase half-bridge inverter circuit to be outputted constantly, the AC output side of the three-phase half-bridge inverter is connected to the LC filter circuit, the filter circuit and the grid connection end are PCC, a sampling circuit is set in the PCC, and the sampling results are output to each link in the control loop respectively, the control loop combines the phase-locked loop output result to output the grid-connected modulation voltage to the PWM generator, and the PWM generator outputs the PWM wave to the three-phase half-bridge inverter to realize grid-connected control; the inertia link is to collect the frequency change of the PLL, set the inertia coefficient, integrate it in combination with the control loop current component deviation, replace the voltage feedforward link in the control loop, and realize the introduction of inertia.

[0115] In summary, the present invention proposes a control method for a grid-connected inverter based on inertia introduction, obtaining a first parameter of a target grid-connected point, and performing a first processing on the first parameter to obtain a second parameter; obtaining a difference between the second parameter and a first given value, and obtaining a first voltage control component based on the difference combined with a preset current controller; calculating a second voltage component based on the first voltage control component, and controlling the grid-connected inverter based on the second voltage component. Based on the frequency response of the PLL, a new voltage feedforward structure is constructed for the control of the GFL grid-connected inverter, and inertia is introduced for the control of the GFL grid-connected inverter, which can effectively suppress the wide-band oscillation of the GFL grid-connected inverter under a weak power grid.

[0116] Example 2

[0117] This embodiment also provides a grid-connected inverter control system based on inertia introduction, including:

[0118] A parameter acquisition module, used for acquiring a first parameter of a target grid connection point, and performing a first processing on the first parameter to obtain a second parameter;

[0119] A component acquisition module, used to acquire a difference between the second parameter and the first given value, and acquire a first voltage control component according to the difference in combination with a preset current controller;

[0120] The control module is used to calculate the second voltage component according to the first voltage control component, and perform grid-connected inverter control according to the second voltage component.

[0121] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0122] This embodiment also provides a computer device, which can be a terminal. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a control method for a grid-connected inverter based on inertia introduction is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the housing of the computer device, or an external keyboard, touchpad or mouse.

[0123] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0124] Acquire a first parameter of a target grid connection point, and perform a first processing on the first parameter to obtain a second parameter;

[0125] Obtaining a difference between the second parameter and the first given value, and obtaining a first voltage control component according to the difference in combination with a preset current controller;

[0126] The second voltage component is calculated according to the first voltage control component, and the grid-connected inverter is controlled according to the second voltage component.

[0127] Example 3

[0128] Reference Figure 3-Figure 4 , which is an embodiment of the present invention, provides a grid-connected inverter control method and system based on inertia introduction. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0129] In order to verify the effectiveness of the method of the present invention, MATLAB / SIMULINK is used to build a simulation model of a traditional GFL grid-connected inverter and a simulation model of a grid-connected inverter control method based on inertia introduction of the present invention.

[0130] Set the system to SCR=10 at time t=0~1s, SCR=5 at time t=1~2s, SCR=2 at time t=2~3s, and SCR=1.1 at time t=3~4s, that is, at t=2s, the new energy grid-connected inverter switches from connecting to a strong grid to a weak grid, and at t=3s, the new energy grid-connected inverter switches from connecting to a weak grid to a very weak grid. The single-phase voltage simulation waveform using the traditional GFL grid-connected inverter control method is as follows: Figure 3 a) is shown, the output power waveform is as follows Figure 4 As shown in (a), the system operates stably under a strong power grid, and starts to oscillate after being connected to a weak power grid. After being connected to an extremely weak power grid, the grid-connected voltage becomes unstable and the output power fluctuates. When a grid-connected inverter control method based on inertia introduction provided by an example of the present invention is adopted, the single-phase voltage simulation waveform is as follows: Figure 3 (b) shows the output power waveform. Figure 4 As shown in (b), the system can operate stably in strong power grids, weak power grids, and even extremely weak power grids, achieving stable grid voltage and stable output power. The above analysis verifies the effectiveness of this solution.

[0131] In summary, by adopting the inertia-based grid-connected inverter control method proposed in an embodiment of the present invention, inertia and damping are introduced into the GFL grid-connected inverter control, which can effectively suppress the grid-connected voltage oscillation of the GFL grid-connected inverter under weak power grid.

[0132] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0133] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0134] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0135] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0136] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0137] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0138] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A control method for a grid-connected inverter based on inertia introduction, characterized in that: include: Acquire a first parameter of a target grid connection point, and perform a first processing on the first parameter to obtain a second parameter; Obtaining a difference between the second parameter and the first given value, and obtaining a first voltage control component according to the difference in combination with a preset current controller; A second voltage component is calculated according to the first voltage control component, and grid-connected inverter control is performed according to the second voltage component.

2. The control method of the grid-connected inverter based on inertia introduction according to claim 1, characterized in that: The controlling of the grid-connected inverter according to the second voltage component comprises: Performing coordinate system transformation according to the second voltage component to obtain a first modulated wave signal; Inputting the first modulation wave signal into a first modulation controller to obtain a first modulation waveform; The grid-connected inverter is controlled according to the first modulation waveform.

3. The control method of the grid-connected inverter based on inertia introduction according to claim 2 is characterized in that: The current controller comprises: The current controller is any controller whose input is the difference between the second parameter and the first given value, and whose output is the first voltage control component.

4. The control method of the grid-connected inverter based on inertia introduction according to claim 3 is characterized in that: The calculating the second voltage component according to the first voltage control component comprises: The second voltage component is calculated according to the first voltage control component in combination with a preset first voltage feedforward output component and a first decoupling component.

5. The control method of the grid-connected inverter based on inertia introduction according to claim 4 is characterized in that: The first voltage feedforward output component comprises: Obtaining a frequency change of a phase-locked loop and comparing it with a d-axis current difference in the difference through proportional coefficient control; The comparison result is integrated to obtain a first voltage feedforward output component.

6. The control method of the grid-connected inverter based on inertia introduction according to claim 5, characterized in that: The step of obtaining the first parameter of the target network connection point includes: Collecting a first parameter of a target grid connection point through a preset sampling circuit; The first parameters include three-phase current and three-phase voltage at the grid connection point.

7. The control method of the grid-connected inverter based on inertia introduction according to claim 6, characterized in that: The obtaining of the difference between the second parameter and the first given value comprises: The second parameter includes a current component and a voltage component; A current component in the second parameter is obtained, and a difference is calculated between the current component in the second parameter and the first given value to obtain a difference between the second parameter and the first given value.

8. A grid-connected inverter control system based on inertia introduction, characterized in that: include: A parameter acquisition module, used for acquiring a first parameter of a target grid connection point, and performing a first processing on the first parameter to obtain a second parameter; A component acquisition module, used to acquire a difference between a second parameter and a first given value, and acquire a first voltage control component according to the difference in combination with a preset current controller; A control module is used to calculate a second voltage component according to the first voltage control component, and to control a grid-connected inverter according to the second voltage component.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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