Control method and device based on inverter, storage medium and electronic equipment

Abstract

The invention discloses a control method and device based on an inverter, a storage medium and electronic equipment. Relates to the technical field of power electronics. The method comprises the steps that voltage data of an inverter side in a grid-connected inverter system are obtained, the grid-connected inverter system at least comprises the inverter side, a filter and a grid-connected side, an inverter is arranged on the inverter side, and the grid-connected side comprises a grid-connected line; the voltage data of the inverter side are input into a state observer, voltage data of a capacitor in a filter are output, and the state observer is used for calculating the voltage data of the capacitor according to a preset calculation formula; and based on the voltage data of the capacitor, current differential of the grid-connected side is calculated to obtain target differential data, and the grid-connected inverter system is controlled based on the target differential data. According to the invention, the technical problem that the control effect is poor when the current differential component is directly calculated through the current to control the inverter in the inverter system in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a control method, device, storage medium and electronic equipment based on an inverter. Background Art

[0002] As an important interface device between renewable energy power generation and the power grid, the stable operation of the converter or inverter is crucial. However, renewable energy is often distributed in remote areas, and power generation equipment often needs to go through 3-4 level transformers before it can be connected to the power grid. Therefore, there is a long electrical distance between the renewable energy power generation equipment and the power grid, which requires long-distance transmission lines. However, long-distance transmission lines have high impedance characteristics, and the power grid is weak. Traditional control methods are difficult to adapt to the situation where the system is unstable.

[0003] In the related art, grid voltage feedforward has been widely used in grid-connected inverter control due to its simple structure and good ability to suppress grid voltage disturbances. However, under large grid impedance, the voltage feedforward method has poor stability. The related art mainly improves the stability of the grid voltage feedforward method under large grid impedance from two aspects.

[0004] On the one hand, the stability of the converter or inverter under large grid impedance is improved through the weighted grid voltage feedforward control strategy. The use of a weighted grid voltage feedforward strategy to reduce the feedforward coefficient can effectively improve system stability and avoid system instability under large grid impedance. The reduction of the feedforward coefficient essentially reduces the impact of voltage feedforward, and voltage feedforward will show a positive feedback effect in a weak grid. Therefore, voltage feedforward should not be used in a weak grid. Whether reducing or completely abandoning voltage feedforward, the burden on the regulator will increase, the response speed will slow down, and the adaptability of the grid-connected converter under small grid impedance will be reduced. The grid-connected converter is susceptible to the background harmonics of the grid voltage.

[0005] On the other hand, virtual impedance is introduced through current differential to reshape the impedance of grid-connected converter. However, the current differential is obtained by directly calculating the differential through current, which cannot avoid the problem of amplifying high-frequency noise. The use of low-pass filter can avoid the amplification of high-frequency noise, but it will introduce phase deviation that cannot be eliminated.

[0006] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0007] The embodiments of the present invention provide a control method, device, storage medium and electronic device based on an inverter to at least solve the technical problem of poor control effect when directly calculating the current differential through the current to control the inverter in the inverter system.

[0008] According to one aspect of an embodiment of the present invention, there is provided an inverter-based control method, comprising: obtaining voltage data of an inverter side in a grid-connected inverter system, wherein the grid-connected inverter system comprises at least: the inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side comprises a grid-connected line; inputting the voltage data of the inverter side into a state observer, and outputting voltage data of a capacitor in the filter, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula; based on the voltage data of the capacitor, calculating the current differential of the grid-connected side to obtain target differential data, and controlling the grid-connected inverter system based on the target differential data.

[0009] Furthermore, based on the voltage data of the capacitor, the current differential of the grid-connected side is calculated to obtain target differential data, including: acquiring the voltage data of the grid-connected side and the inductance data of the grid-connected side; and determining the target differential data based on the voltage data of the capacitor, the voltage data of the grid-connected side and the inductance data of the grid-connected side.

[0010] Further, based on the voltage data of the capacitor, the voltage data of the grid-connected side and the inductance data of the grid-connected side, the target differential data is determined, including: based on the voltage data of the capacitor and the voltage data of the grid side, calculating the difference between the voltage of the capacitor and the voltage of the grid-connected side to obtain a first difference; based on the first difference and the inductance data of the grid-connected side, determining the target differential data.

[0011] Furthermore, the grid-connected inverter system is controlled based on the target differential data, including: obtaining a preset current value, wherein the preset current value represents the current value that the grid-connected inverter system needs to reach; collecting the current value of the grid-connected inverter system at the current moment to obtain a target current value; and controlling the grid-connected inverter system based on the preset current value, the target current value and the target differential data.

[0012] Furthermore, the grid-connected inverter system is controlled based on the preset current value, the target current value and the target differential data, including: calculating the difference between the preset current value and the target current value to obtain a second difference; calculating the product of the target differential data and a preset feedback coefficient to obtain a target calculation result; and controlling the grid-connected inverter system based on the second difference and the target calculation result.

[0013] Furthermore, based on the second difference and the target calculation result, the grid-connected inverter system is controlled, including: based on the second difference and the target calculation result, a first feedback signal is generated, and the first feedback signal is input into a target regulator to output a second feedback signal, wherein the type of the target regulator includes: a proportional-integral regulator; based on the second feedback signal and a pulse width modulation strategy, the grid-connected inverter system is controlled.

[0014] Furthermore, the inverter includes: multiple switching devices, and the grid-connected inverter system is controlled based on the second feedback signal and the pulse width modulation strategy, including: based on the second feedback signal, using the pulse width modulation strategy to generate a switching signal; using the switching signal to control the multiple switching devices to control the grid-connected inverter system.

[0015] According to another aspect of an embodiment of the present invention, there is also provided an inverter-based control device, comprising: an acquisition unit, for acquiring voltage data on the inverter side of a grid-connected inverter system, wherein the grid-connected inverter system at least comprises: the inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side comprises a grid-connected line; a first processing unit, for inputting the voltage data on the inverter side into a state observer, and outputting voltage data of a capacitor in the filter, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula; a second processing unit, for calculating the current differential of the grid-connected side based on the voltage data of the capacitor, obtaining target differential data, and controlling the grid-connected inverter system based on the target differential data.

[0016] Furthermore, the second processing unit includes: a first acquisition subunit, used to acquire the voltage data of the grid-connected side and the inductance data of the grid-connected side; a first determination subunit, used to determine the target differential data based on the voltage data of the capacitor, the voltage data of the grid-connected side and the inductance data of the grid-connected side.

[0017] Furthermore, the first determination subunit includes: a first calculation module, used to calculate the difference between the voltage of the capacitor and the voltage of the grid-connected side based on the voltage data of the capacitor and the voltage data of the grid side, to obtain a first difference; a determination module, used to determine the target differential data based on the first difference and the inductance data of the grid-connected side.

[0018] Furthermore, the second processing unit includes: a second acquisition subunit, used to acquire a preset current value, wherein the preset current value represents the current value that the grid-connected inverter system needs to reach; a collection subunit, used to collect the current value of the grid-connected inverter system at the current moment to obtain a target current value; and a control subunit, used to control the grid-connected inverter system based on the preset current value, the target current value and the target differential data.

[0019] Furthermore, the control subunit includes: a second calculation module, used to calculate the difference between the preset current value and the target current value to obtain a second difference; a third calculation module, used to calculate the product of the target differential data and a preset feedback coefficient to obtain a target calculation result; and a control module, used to control the grid-connected inverter system based on the second difference and the target calculation result.

[0020] Furthermore, the control module includes: a processing subunit, used to generate a first feedback signal based on the second difference and the target calculation result, and input the first feedback signal into a target regulator, and output a second feedback signal, wherein the type of the target regulator includes: a proportional-integral regulator; a control submodule, used to control the grid-connected inverter system based on the second feedback signal and a pulse width modulation strategy.

[0021] Furthermore, the inverter includes: multiple switching devices, and the control submodule includes: a generation module 1, which is used to generate a switching signal based on the second feedback signal using a pulse width modulation strategy; a control module 1, which uses the switching signal to control the multiple switching devices to control the grid-connected inverter system.

[0022] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to execute any one of the above inverter-based control methods by executing the executable instructions.

[0023] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided, which stores a computer program, wherein when the computer program runs, the device where the computer-readable storage medium is located is controlled to execute any one of the above-mentioned inverter-based control methods.

[0024] In the present invention, the voltage data of the inverter side in the grid-connected inverter system is obtained, wherein the grid-connected inverter system at least includes: an inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side includes a grid-connected line; the voltage data of the inverter side is input into a state observer, and the voltage data of the capacitor in the filter is output, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula; based on the voltage data of the capacitor, the current differential of the grid-connected side is calculated to obtain the target differential data, and the grid-connected inverter system is controlled based on the target differential data. Thus, the technical problem of poor control effect of directly calculating the current differential by current in the related art to control the inverter in the inverter system is solved. In the present invention, the voltage data of the capacitor in the filter is observed by an observer, and then the differential of the grid-connected side current is calculated according to the voltage data, thereby avoiding the situation in the related art that the current differential is directly calculated by overcurrent, which will introduce high-frequency noise, resulting in inaccurate calculation results and affecting the stability of the inverter system, thereby achieving the technical effect of improving the stability of the inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 is a flow chart of an optional inverter-based control method according to an embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of an optional grid-connected inverter system and a conventional voltage feedforward control according to an embodiment of the present invention;

[0028] Figure 3 is an optional current differential observer and d-axis virtual impedance control block diagram according to an embodiment of the present invention;

[0029] Figure 4 It is an optional grid-connected voltage and current simulation waveform diagram under traditional voltage feedforward control in a weak power grid in the related technology;

[0030] Figure 5 is a grid connection point voltage and current waveform under an optional virtual impedance control according to an embodiment of the present invention;

[0031] Figure 6 It is a voltage and current waveform of a grid connection point under virtual impedance control in an optional strong power grid according to an embodiment of the present invention;

[0032] Figure 7This is a comparison diagram of d-axis current under an optional strong power grid using the inverter-based control method proposed by the present invention and a traditional voltage feedforward control;

[0033] Figure 8 is a schematic diagram of an optional inverter-based control device according to an embodiment of the present invention;

[0034] Fig. 9 is a schematic diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] Embodiment 1

[0038] According to an embodiment of the present invention, an optional method embodiment of an inverter-based control method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0039] Figure 1 is a flow chart of an optional inverter-based control method according to an embodiment of the present invention, such as Figure 1 As shown, the method comprises the following steps:

[0040] Step S101, obtaining voltage data of the inverter side in the grid-connected inverter system, wherein the grid-connected inverter system at least includes: an inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side includes a grid-connected line.

[0041] Figure 2 is a schematic diagram of an optional grid-connected inverter system and a traditional voltage feedforward control according to an embodiment of the present invention, such as Figure 2 As shown, the grid-connected inverter system may include: a voltage source converter, a DC line, a DC side voltage stabilizing capacitor, an AC grid, a line equivalent inductance, an LCL filter, and a traditional control structure. The main circuit parameters include the DC side current i d , inverter side current i1, inverter side inductor L1, capacitor C1, grid side (i.e. grid-connected side) inductor L2, U dc is the DC side voltage, C dc is the DC side capacitance, S i (i=1…6) is an IGBT (insulated gate bipolar transistor) fully controlled switching device. invi (i=a,b,c) is the three-phase voltage output by the inverter, u g 、i g is the grid-connected voltage and current value collected by the voltage and current sensors, u c is the voltage on the capacitor, i c is the current on the capacitor, L g is the grid line inductance, r g is the grid line resistance, e i (i=a,b,c) is the ideal voltage of the power grid, i * gd 、i * gq The dq axis current is given when the system is running. The traditional voltage feedforward control part includes: SPWM (sinusoidal pulse width modulation) modulation, abc three-phase, capacitor current feedback coefficient K c , phase θ, PI regulator (proportional-integral regulator), i gd 、i gq It is the dq axis current, PLL (phase locked loop), and PCC (programmable computer controller) when the system is running.

[0042] In this embodiment, the inverter on the inverter side can be connected to the filter, the filter side can be connected to the grid-connected side, the inverter side is provided with an inverter, the filter type can be an LCL filter, and the grid-connected line on the grid-connected side is as follows: Figure 2 The dashed box part of the power grid.

[0043] The voltage data on the inverter side in the grid-connected inverter system may include the voltages of the dq axes on the inverter side.

[0044] Step S102, inputting the voltage data of the inverter side into the state observer, and outputting the voltage data of the capacitor in the filter, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula.

[0045] The calculation process of the dq-axis state space model of the AC side of the VSC converter and the establishment process of the current differential observer are given below.

[0046] First, we can list the AC side model (or LCL inverter model). To simplify the model, the following assumptions are made: (1) Ignore the dead zone delay of the switching device; (2) The grid voltage is an ideal voltage source; (3) Ignore the inverter output delay; (4) Ignore the parasitic resistance parameters and coupling phases of the filter inductor and capacitor. According to Kirchhoff's voltage and current law, the AC side differential equation can be obtained. The differential equation in the three-phase coordinate system is park transformed to obtain the state equation of the LCL type converter AC side dq axis (corresponding to the preset calculation formula).

[0047]

[0048] Among them, x' represents the observation value of the state observer (that is, the result of the state observer output), y represents the inverter side current, dq axis system matrix A, input matrix B, state variable x, output matrix C:

[0049]

[0050] Among them, u invd Indicates the d-axis voltage on the inverter side, u invq represents the q-axis voltage on the inverter side, and Indicates the inverter measurement of dq axis current, Indicates the grid-connected current, Indicates the grid-connected capacitor voltage.

[0051] Figure 3 is an optional current differential observer and d-axis virtual impedance control block diagram according to an embodiment of the present invention, such as Figure 3 As shown, the LCL inverter model is listed. Through the state observer, the dq axis capacitor voltage is directly observed, where: Figure 3 middle u imd Indicates the d-axis voltage on the inverter side, u imq represents the q-axis voltage on the inverter side, u gdq Indicates the dq axis voltage on the grid side, i gdq Indicates the dq axis current on the grid side, Represents the dq-axis capacitor current output by the state observer, represents the dq-axis capacitor current output by the state observer, L represents the inductance, z1' and z2' represent the d-axis current differential and q-axis current differential on the grid-connected side, respectively, i gd * Indicates a given current value, H i Indicates the current loop coefficient, K f Represents the voltage feed-forward coefficient, K d Indicates the preset feedback coefficient (differential feedback coefficient), G i (s) represents PI regulator (proportional-integral regulator), Kc represents capacitor current feedback coefficient, s represents Laplace operator, e d Represents the ideal grid voltage.

[0052] Step S103, based on the voltage data of the capacitor, the current differential of the grid-connected side is calculated to obtain the target differential data, and the grid-connected inverter system is controlled based on the target differential data.

[0053] In this embodiment, after obtaining the dq-axis capacitor voltage (corresponding to the capacitor voltage data) axis, the dq-axis capacitor voltage is subtracted from the grid-connected point voltage to obtain the grid-side inductor voltage. The relationship between the voltage and current on the grid-side inductor is used to obtain the equivalent grid-connected current differential (corresponding to the current differential on the grid-connected side). The grid-connected current differential is superimposed and fed back with the grid-connected current. The virtual inductance value is adjusted using the differential feedback coefficient (i.e., the grid-connected inverter system is controlled) to increase the electrical distance between the filter and the grid-connected point, thereby improving the stability of the grid-connected system under a weak power grid and reducing the system overshoot.

[0054] Through the above steps, in this embodiment, the voltage data of the capacitor in the filter is observed by the observer, and then the differential of the grid-connected current is calculated according to the voltage data, thereby avoiding the situation in the related art where the current differential is directly calculated by overcurrent, which will introduce high-frequency noise, lead to inaccurate calculation results, and affect the stability of the inverter system, thereby achieving the technical effect of improving the stability of the inverter system. Furthermore, the technical problem of poor control effect in the related art where the current differential is directly calculated by current to control the inverter in the inverter system is solved.

[0055] Optionally, based on the voltage data of the capacitor, the current differential on the grid-connected side is calculated to obtain target differential data, including: obtaining the voltage data on the grid-connected side and the inductance data on the grid-connected side; based on the voltage data of the capacitor, the voltage data on the grid-connected side and the inductance data on the grid-connected side, determining the target differential data.

[0056] For example, the current differential equation on the grid-side inductor of the grid-connected inverter can be obtained, the inductor current differential can be equivalent to the product of the inductor voltage and the inverse of the inductance, the inductor voltage can be determined by the capacitor voltage data and the grid-connected side voltage data, and then the target differential data is determined based on the product of the inductor voltage and the inverse of the inductance.

[0057] Optionally, based on the voltage data of the capacitor, the voltage data of the grid-connected side, and the inductance data of the grid-connected side, the target differential data is determined, including: based on the voltage data of the capacitor and the voltage data of the grid side, calculating the difference between the voltage of the capacitor and the voltage of the grid-connected side to obtain a first difference; based on the first difference and the inductance data of the grid-connected side, determining the target differential data.

[0058] According to the current differential equation of the grid-side inductor of the grid-connected inverter, the differential of the inductor current can be equivalent to the product of the inductor voltage and the inverse of the inductance, and the expression is:

[0059]

[0060] Among them, u cd represents the capacitor voltage on the d-axis, u cq The q-axis capacitor voltage, u gd Indicates the voltage of the d-axis on the grid-connected side, u gq represents the voltage of the q axis on the grid-connected side, L2 represents the inductance on the grid-connected side, represents the current differential of the d-axis, Indicates the current differential of the q-axis.

[0061] In order to eliminate the noise interference of capacitor voltage sampling and the use of redundant sensors, the state observer output capacitor voltage state variable is used instead, and the equivalent current differential expression can be further expressed as:

[0062]

[0063] in, and Corresponding to the first difference (i.e., the inductor voltage), represents the capacitance voltage of the d-axis obtained by the state observer, represents the capacitor voltage on the q-axis obtained by the state observer.

[0064] Optionally, the grid-connected inverter system is controlled based on the target differential data, including: obtaining a preset current value, wherein the preset current value represents the current value that the grid-connected inverter system needs to reach; collecting the current value of the grid-connected inverter system at the current moment to obtain the target current value; and controlling the grid-connected inverter system based on the preset current value, the target current value and the target differential data.

[0065] In this embodiment, during the control of the virtual impedance of the inverter of the grid-connected inverter system, the grid-connected current differential (corresponding to the target differential data) multiplied by the feedback coefficient (differential feedback coefficient, corresponding to the preset feedback coefficient) can be superimposed with the grid-connected current and fed back to the input and the reference input for difference. For example, the current value at the current moment (i.e., the target current value) is differentiated from the given current value (corresponding to the preset current value) as feedback, and then superimposed with the product of the target differential data and the preset feedback coefficient. According to the superposition result, it is used as feedback of the grid-connected inverter system to increase the electrical distance by equivalent virtual impedance, thereby improving the stability of the grid-connected inverter system under weak power grid.

[0066] Optionally, the grid-connected inverter system is controlled based on a preset current value, a target current value and a target differential data, including: calculating the difference between the preset current value and the target current value to obtain a second difference; calculating the product of the target differential data and a preset feedback coefficient to obtain a target calculation result; and controlling the grid-connected inverter system based on the second difference and the target calculation result.

[0067] like Figure 3 As shown, in this embodiment, the current value at the current moment (i.e., the target current value, corresponding to Figure 3 i gd ) and a given current value (corresponding to a preset current value, corresponding to Figure 3 i gd * ) is subtracted, the target differential data (corresponding to Figure 3 z1') and the preset feedback coefficient (corresponding to Figure 3 k d (differential feedback coefficient)) are multiplied, and then the grid-connected inverter system can be controlled based on the second difference and the target calculation result.

[0068] Optionally, based on the second difference and the target calculation result, the grid-connected inverter system is controlled, including: based on the second difference and the target calculation result, a first feedback signal is generated, and the first feedback signal is input into a target regulator to output a second feedback signal, wherein the type of the target regulator includes: a proportional-integral regulator; based on the second feedback signal and a pulse width modulation strategy, the grid-connected inverter system is controlled.

[0069] In this embodiment, the second difference (ie, the difference between the preset current value and the target current value) is i (current loop coefficient) is superimposed (for example, the product is calculated), and then superimposed with the target calculation result to obtain a first feedback signal, which is then input into the target regulator (corresponding to Figure 3 G i (s)) outputs a second feedback signal, and then based on the second feedback signal, pulse width modulation (corresponding to Figure 3K PWM ) method to control the grid-connected inverter system.

[0070] Optionally, the inverter includes: multiple switching devices, which control the grid-connected inverter system based on the second feedback signal and the pulse width modulation strategy, including: generating a switching signal based on the second feedback signal using the pulse width modulation strategy; and controlling the multiple switching devices using the switching signal to control the grid-connected inverter system.

[0071] Based on the second feedback signal and the preset rule, a switching signal is generated using a pulse width modulation strategy, for example, Figure 3 As shown, based on the second feedback signal ( Figure 3 G i (s)) outputs a second feedback signal), a capacitor current feedback coefficient and a voltage pre-feedback coefficient, uses a pulse width modulation strategy to generate a switching signal, feeds the switching signal back to multiple switching devices of the inverter in the grid-connected inverter system, controls the switching devices in the inverter, and thus realizes control of the inverter in the grid-connected inverter system.

[0072] Figure 4 It is an optional grid-connected voltage and current simulation waveform diagram under traditional voltage feedforward control under weak power grid in related technology, such as Figure 4 As shown in the simulation waveform, it can be seen that the traditional voltage feedforward control is unstable under weak power grid, the voltage and current oscillate, and the system cannot operate stably.

[0073] Figure 5 is a grid connection point voltage and current waveform under an optional virtual impedance control according to an embodiment of the present invention. By comparing Figure 4 , Figure 5 When the current is given in a weak power grid, this embodiment can maintain the stable operation of the grid-connected inverter, and the voltage and current harmonic content is less than 5% to meet the grid-connected requirements.

[0074] Figure 6 is a voltage and current waveform of the grid connection point under virtual impedance control in an optional strong power grid according to an embodiment of the present invention, from Figure 6 It can be seen from the figure that this embodiment still has strong applicability under a strong power grid, where: Figure 5 and Figure 6 The THD in it stands for total harmonic distortion.

[0075] Figure 7 is a comparison diagram of the d-axis current under the inverter-based control method proposed by the present invention and the traditional voltage feedforward control under an optional strong power grid according to an embodiment of the present invention, from Figure 7It can be seen that, in this embodiment, when the current is given a step, the d-axis current overshoot can be effectively reduced, and the system output can be guaranteed to have no steady-state error, thereby ensuring stable operation of the system.

[0076] The inverter-based control method provided in this embodiment can be applied to a grid-connected inverter system under a weak power grid. The grid-connected inverter system may include: a voltage source converter VSC, a DC line and a DC side stabilizing capacitor, an AC line, an AC side LCL filter, an AC side line equivalent inductance, and a control strategy. The control strategy includes: writing an LCL inverter model, obtaining an equivalent grid-connected current differential through a state observer, and introducing the equivalent grid-connected current differential for control; subtracting the equivalent current differential (corresponding to the target differential data), the current measurement value (corresponding to the target current value) from the current given amount (corresponding to the preset current value), adding a proportional integral link, and correcting the reference input.

[0077] The state observer is designed according to the LCL inverter model. The state observer is used to observe the capacitor voltage state (corresponding to the capacitor voltage data) and measure the grid-connected point voltage, and then the grid-connected current differential is equivalent to the ratio of the grid-side inductance. The grid-connected current differential is multiplied by the feedback coefficient and superimposed with the grid-connected current feedback to form virtual impedance control.

[0078] It should be noted that, in this embodiment, the state observer poles can be configured at positions three times farther away from the system zero poles.

[0079] In this embodiment, direct calculation and the use of low-pass filters are avoided by observing the current differential component, so there is no problem of amplifying high-frequency noise and phase lag. The feedback control of the current differential component increases the system damping, which can effectively reduce the overshoot on the AC side, and can also improve the stability of the grid-connected inverter under a weak power grid, and does not change the inhibitory effect of the traditional voltage feedforward on the voltage background harmonics. Through this embodiment, when the current is given in a weak power grid, the grid-connected inverter can be maintained to operate stably, and the voltage and current harmonic content is less than 5%, which meets the grid connection requirements and solves the problems in the related technology that the voltage feedforward control is unstable under a weak power grid, the voltage and current oscillate, the system cannot operate stably, and the grid-connected voltage and current harmonic content is small under a strong power grid. Therefore, through this embodiment, the d-axis current overshoot can be effectively reduced, and the system output can be guaranteed to have no steady-state error, thereby ensuring the stable operation of the system.

[0080] Embodiment 2

[0081] Embodiment 2 of the present invention provides an optional inverter-based control device, in which each implementation unit in the inverter-based control device corresponds to each implementation step in Embodiment 1.

[0082] Figure 8 is a schematic diagram of an optional inverter-based control device according to an embodiment of the present invention, such as Figure 8 As shown, it includes: an acquisition unit 81, a first processing unit 82 and a second processing unit 83.

[0083] An acquisition unit 81 is used to acquire voltage data of an inverter side in a grid-connected inverter system, wherein the grid-connected inverter system at least includes: an inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side includes a grid-connected line;

[0084] A first processing unit 82 is used to input the voltage data of the inverter side into the state observer, and output the voltage data of the capacitor in the filter, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula;

[0085] The second processing unit 83 is used to calculate the current differential on the grid-connected side based on the voltage data of the capacitor, obtain target differential data, and control the grid-connected inverter system based on the target differential data.

[0086] In the inverter-based control device provided in the second embodiment of the present invention, the voltage data of the inverter side in the grid-connected inverter system can be obtained by the acquisition unit 81, wherein the grid-connected inverter system at least includes: an inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, the grid-connected side includes a grid-connected line, the voltage data of the inverter side is input into the state observer through the first processing unit 82, and the voltage data of the capacitor in the filter is output, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula, and the current differential of the grid-connected side is calculated based on the voltage data of the capacitor through the second processing unit 83 to obtain the target differential data, and the grid-connected inverter system is controlled based on the target differential data. Thus, the technical problem of poor control effect in the related art of directly calculating the current differential through the current to control the inverter in the inverter system is solved. In this embodiment, the voltage data of the capacitor in the filter is observed by an observer, and then the differential of the grid-connected current is calculated based on the voltage data, thereby avoiding the situation in the related art where the overcurrent directly calculates the current differential, which introduces high-frequency noise, causes inaccurate calculation results, and affects the stability of the inverter system, thereby achieving the technical effect of improving the stability of the inverter system.

[0087] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the second processing unit includes: a first acquisition subunit, used to acquire voltage data on the grid-connected side and inductance data on the grid-connected side; a first determination subunit, used to determine target differential data based on the voltage data of the capacitor, the voltage data on the grid-connected side and the inductance data on the grid-connected side.

[0088] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the first determination subunit includes: a first calculation module, used to calculate the difference between the voltage of the capacitor and the voltage on the grid side based on the voltage data of the capacitor and the voltage data on the grid side, to obtain a first difference; a determination module, used to determine the target differential data based on the first difference and the inductance data on the grid side.

[0089] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the second processing unit includes: a second acquisition subunit, used to acquire a preset current value, wherein the preset current value represents the current value required to be reached by the grid-connected inverter system; a collection subunit, used to collect the current value of the grid-connected inverter system at the current moment to obtain a target current value; and a control subunit, used to control the grid-connected inverter system based on the preset current value, the target current value and the target differential data.

[0090] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the control subunit includes: a second calculation module, used to calculate the difference between the preset current value and the target current value to obtain a second difference; a third calculation module, used to calculate the product of the target differential data and the preset feedback coefficient to obtain a target calculation result; and a control module, used to control the grid-connected inverter system based on the second difference and the target calculation result.

[0091] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the control module includes: a processing subunit, used to generate a first feedback signal based on the second difference and the target calculation result, and input the first feedback signal into a target regulator, and output a second feedback signal, wherein the types of target regulators include: a proportional-integral regulator; a control submodule, used to control the grid-connected inverter system based on the second feedback signal and a pulse width modulation strategy.

[0092] Optionally, in the inverter-based control device provided in Embodiment 2 of the present invention, the inverter includes: multiple switching devices, and the control submodule includes: a generation module one, which is used to generate a switching signal based on the second feedback signal and using a pulse width modulation strategy; a control module one, which uses the switching signal to control the multiple switching devices to control the grid-connected inverter system.

[0093] The inverter-based control device may further include a processor and a memory. The acquisition unit 81, the first processing unit 82 and the second processing unit 83 are all stored in the memory as program units, and the processor executes the program units stored in the memory to implement corresponding functions.

[0094] The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the voltage data of the capacitor in the filter is observed by the observer through the kernel parameters, and then the differential of the grid-connected current is calculated according to the voltage data, thereby avoiding the situation in the related art where the current differential is directly calculated due to overcurrent, which will introduce high-frequency noise, resulting in inaccurate calculation results and affecting the stability of the inverter system, thereby achieving the technical effect of improving the stability of the inverter system. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one storage chip.

[0095] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to execute any one of the above inverter-based control methods by executing the executable instructions.

[0096] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided, which stores a computer program, wherein when the computer program runs, the device where the computer-readable storage medium is located is controlled to execute any one of the above-mentioned inverter-based control methods.

[0097] Fig. 9 is a schematic diagram of an electronic device according to an embodiment of the present invention, such as Fig. 9 As shown, an embodiment of the present invention provides an electronic device 90, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, any one of the above inverter-based control methods is implemented.

[0098] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0099] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0100] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0101] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0102] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0103] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, 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, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0104] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A control method based on an inverter, characterized in that: include: Acquire voltage data of an inverter side in a grid-connected inverter system, wherein the grid-connected inverter system at least includes: the inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side includes a grid-connected line; Inputting the voltage data of the inverter side into a state observer, and outputting the voltage data of the capacitor in the filter, wherein the state observer is used to calculate the voltage data of the capacitor according to a preset calculation formula; Based on the voltage data of the capacitor, the current differential of the grid-connected side is calculated to obtain target differential data, and the grid-connected inverter system is controlled based on the target differential data.

2. The control method according to claim 1, characterized in that: Based on the voltage data of the capacitor, the current differential of the grid-connected side is calculated to obtain target differential data, including: Acquiring voltage data of the grid-connected side and inductance data of the grid-connected side; The target differential data is determined based on the voltage data of the capacitor, the voltage data of the grid-connected side, and the inductance data of the grid-connected side.

3. The control method according to claim 2, characterized in that: Determining the target differential data based on the voltage data of the capacitor, the voltage data of the grid-connected side, and the inductance data of the grid-connected side includes: Based on the voltage data of the capacitor and the voltage data of the grid side, calculating the difference between the voltage of the capacitor and the voltage of the grid side to obtain a first difference; The target differential data is determined based on the first difference and the inductance data of the grid-connected side.

4. The control method according to claim 1, characterized in that: Controlling the grid-connected inverter system based on the target differential data includes: Obtaining a preset current value, wherein the preset current value represents the current value that the grid-connected inverter system needs to reach; Collecting the current value of the grid-connected inverter system at the current moment to obtain a target current value; The grid-connected inverter system is controlled based on the preset current value, the target current value and the target differential data.

5. The control method according to claim 4, characterized in that: Controlling the grid-connected inverter system based on the preset current value, the target current value and the target differential data includes: Calculating a difference between the preset current value and the target current value to obtain a second difference; Calculating the product of the target differential data and a preset feedback coefficient to obtain a target calculation result; Based on the second difference and the target calculation result, the grid-connected inverter system is controlled.

6. The control method according to claim 5, characterized in that: Based on the second difference and the target calculation result, controlling the grid-connected inverter system includes: Based on the second difference and the target calculation result, a first feedback signal is generated, and the first feedback signal is input into a target regulator, and a second feedback signal is output, wherein the type of the target regulator includes: a proportional-integral regulator; Based on the second feedback signal and the pulse width modulation strategy, the grid-connected inverter system is controlled.

7. The control method according to claim 6, characterized in that: The inverter includes: a plurality of switch devices, and based on the second feedback signal and the pulse width modulation strategy, controls the grid-connected inverter system, including: Based on the second feedback signal, a switching signal is generated by using a pulse width modulation strategy; The switching signal is used to control the plurality of switching devices to control the grid-connected inverter system.

8. A control device based on an inverter, characterized in that: include: An acquisition unit, used for acquiring voltage data of an inverter side in a grid-connected inverter system, wherein the grid-connected inverter system at least comprises: the inverter side, a filter and a grid-connected side, the inverter side is provided with an inverter, and the grid-connected side comprises a grid-connected line; A first processing unit, configured to input the voltage data of the inverter side into a state observer, and output the voltage data of the capacitor in the filter, wherein the state observer is configured to calculate the voltage data of the capacitor according to a preset calculation formula; The second processing unit is used to calculate the current differential of the grid-connected side based on the voltage data of the capacitor, obtain target differential data, and control the grid-connected inverter system based on the target differential data.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the inverter-based control method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: It includes one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the inverter-based control method described in any one of claims 1 to 7.

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