Active filtering function multiplexing control method and device of network-forming inverter

Abstract

The invention discloses a multiplexing control method and device for an active filtering function of a network-forming inverter. The method comprises the following steps: acquiring real-time operation parameters of an inverter; wherein the real-time operation parameters at least comprise grid-side current, grid-connected point voltage and capacitor voltage of a filter capacitor; determining a reference voltage corresponding to the inverter according to the grid-side current, the capacitor voltage and a preset working parameter; respectively extracting harmonic components corresponding to the capacitor voltage and the grid-connected point voltage to obtain a corresponding capacitor voltage harmonic component and a grid-connected point voltage harmonic component; determining a reference voltage harmonic component according to the capacitor voltage harmonic component and the grid-connected point voltage harmonic component; determining a target control parameter according to the capacitor voltage, the reference voltage and the reference voltage harmonic component; and controlling a switching device of the inverter according to the target control parameter. The active filtering function is seamlessly integrated in the topological structure of the existing network-forming inverter, so that the harmonic compensation of a local nonlinear load can be realized, and meanwhile, the application scene is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-connected power generation, and in particular to an active filter function multiplexing control method and device of a grid-connected inverter. Background Art

[0002] As distributed energy sources such as photovoltaics, wind power and energy storage account for an increasing proportion of new power systems, their grid-side inverters have gradually begun to transition from the original grid-following control mode to grid-building control to maintain grid frequency stability.

[0003] In the prior art, the hardware topology of the grid-type inverter and the active filtering device have commonalities, both of which are based on the topology of the three-phase full-bridge inverter. At the same time, under most operating conditions, the active power output of the inverter does not reach its rated value, resulting in a waste of inverter capacity. Therefore, multiplexing inverters for active filtering has high research and practical value.

[0004] Although there were some sporadic ideas about reusing inverters for active filtering in the early days, they were all in the inverter's grid-following mode, that is, in the current source output mode, and the harmonic current resonant control loop was further superimposed on the closed-loop control of the baseband current. However, for grid-forming control, its essence is to perform closed-loop control on the baseband voltage vector, and its control architecture is completely different from that of grid-following control. Therefore, how to reuse the active filtering function on the grid-forming control architecture is a problem that needs to be solved. Summary of the invention

[0005] The present invention provides a method and device for multiplexing control of active filtering functions of a meshed inverter, so as to solve the problem of multiplexing and realizing active filtering functions on a meshed control architecture.

[0006] According to one aspect of the present invention, a method for multiplexing control of active filtering functions of a grid-connected inverter is provided, the method comprising:

[0007] Acquire real-time operating parameters of the inverter; wherein the real-time operating parameters include at least: grid-side current, grid-connection point voltage, and capacitor voltage of the filter capacitor;

[0008] Determine the reference voltage corresponding to the inverter according to the grid-side current, capacitor voltage and preset working parameters;

[0009] Extracting the harmonic components corresponding to the capacitor voltage and the grid-connected point voltage respectively, and obtaining the corresponding capacitor voltage harmonic components and grid-connected point voltage harmonic components;

[0010] Determine the reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component;

[0011] Determine a target control parameter according to the capacitor voltage, the reference voltage and the harmonic component of the reference voltage;

[0012] The switching devices of the inverter are controlled according to the target control parameters.

[0013] According to another aspect of the present invention, there is provided an active filter function multiplexing control device for a grid-type inverter, the device comprising:

[0014] A parameter acquisition module is used to acquire real-time operating parameters of the inverter; wherein the real-time operating parameters include at least: grid-side current, grid-connection point voltage and capacitor voltage of the filter capacitor;

[0015] A reference voltage determination module is used to determine a reference voltage corresponding to the inverter according to the grid-side current, capacitor voltage and preset working parameters;

[0016] A harmonic extraction module is used to extract the harmonic components corresponding to the capacitor voltage and the grid connection point voltage respectively, and obtain the corresponding capacitor voltage harmonic components and grid connection point voltage harmonic components;

[0017] A harmonic compensation module, used to determine the reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component;

[0018] A target control parameter determination module, used to determine the target control parameter according to the capacitor voltage, the reference voltage and the harmonic component of the reference voltage;

[0019] The inverter control module is used to control the switching devices of the inverter according to the target control parameters.

[0020] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0021] at least one processor; and

[0022] a memory communicatively connected to the at least one processor; wherein,

[0023] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the active filtering function multiplexing control method of the grid-type inverter described in any embodiment of the present invention.

[0024] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the active filtering function multiplexing control method of a grid-connected inverter as described in any embodiment of the present invention when executed.

[0025] The technical solution of the embodiment of the present invention respectively extracts the harmonic components corresponding to the capacitor voltage and the grid-connected point voltage of the inverter, and then uses the harmonic components of the two to determine the corresponding reference voltage harmonic components, and then determines the target control parameters according to the capacitor voltage, the reference voltage and the reference voltage harmonic components, and then controls the switching devices of the inverter according to the target control parameters, thereby solving the problem of multiplexing the active filtering function on the meshing control architecture, and realizing the seamless integration of the active filtering function in the existing meshing inverter topology structure, thereby realizing compensation for the harmonic current generated by the local nonlinear load, reducing the harmonic current in the inverter output current, thereby improving the power quality of the power grid, and having a wide range of application scenarios.

[0026] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of 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 work.

[0028] Figure 1 1 is a schematic diagram of a topological structure of an active filtering function multiplexing control system of a grid-type inverter provided according to Embodiment 1 of the present invention;

[0029] Figure 2 This is a flow chart of an active filtering function multiplexing control method of a grid-type inverter provided according to Embodiment 1 of the present invention;

[0030] Figure 3 1 is a schematic diagram of the topological structure of an active filtering function multiplexing control system of a grid-type inverter provided according to the second embodiment of the present invention;

[0031] Figure 4 is a flow chart of an active filtering function multiplexing control method of a grid-type inverter provided according to a second embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of the structure of a harmonic compensation module provided according to Embodiment 2 of the present invention;

[0033] Figure 6 is a schematic diagram of the structure of a voltage and current closed-loop control module provided according to Embodiment 2 of the present invention;

[0034] Figure 71 is a schematic diagram of the structure of an active filtering function multiplexing control device for a grid-type inverter provided according to a third embodiment of the present invention;

[0035] Figure 8 It is a structural schematic diagram of an electronic device for implementing the active filter function multiplexing control method of a grid-type inverter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] Embodiment 1

[0039] Figure 1 The topological structure diagram of an active filter function multiplexing control system of a grid-type inverter provided in the first embodiment of the present invention is shown in FIG. Figure 1 As shown, the active filtering function multiplexing control system includes: an inverter, a reference voltage calculation module, a voltage harmonic component extraction module, a harmonic compensation module, a voltage and current closed-loop control module, and a PWM modulation module. The structure of the active filtering function multiplexing control system of this embodiment is specifically described below.

[0040] Reference voltage calculation module, used to calculate the voltage based on preset working parameters and the collected grid-side current i2 and capacitor voltage u c And determine the reference voltage u corresponding to the inverter through any kind of network algorithm ref .

[0041] Voltage harmonic component extraction module, used to extract capacitor voltage u cand grid voltage u pcc The corresponding harmonic component is the capacitor voltage harmonic component u c.h And the grid-connected voltage harmonic component u pcc.h .

[0042] The harmonic compensation module is used to compensate the capacitor voltage harmonic component u c.h And the grid-connected voltage harmonic component u pcc.h , determine the reference voltage harmonic component u for compensating the harmonic current generated by the local nonlinear load ref.h , which is the harmonic voltage command of active filtering.

[0043] The voltage and current closed-loop control module is used to control the capacitor voltage u c , reference voltage u ref and the reference voltage harmonic component u ref.h Determine the corresponding target control parameters.

[0044] The PWM modulation module is used to output a corresponding PWM modulation signal according to the target control parameter to control the switching device of the inverter.

[0045] like Figure 1 As shown in Figure 1, the grid-connected inverter and the AC grid intersect at the common coupling point (PCC), and the PCC serves as the access end of the nonlinear load. dc is the DC side voltage of the inverter; L1 is the inductance of the inverter output filter; i1 is the current output by the output end of the inverter; C is the capacitance of the inverter output filter; u c is the capacitor voltage of the inverter filter capacitor, that is, the voltage output by the inverter; Z line is the equivalent impedance of the inverter connected to the grid; u pcc is the voltage at PCC; i g is the grid-side current of the inverter; L g The equivalent inductance of the grid to which the inverter is connected; u g is the grid voltage; i Load is the current corresponding to the local nonlinear load.

[0046] Based on the above active filtering function multiplexing control system, Figure 2This is a flow chart of a method for multiplexing active filter functions of a meshed inverter provided in the first embodiment of the present invention. This embodiment can be applied to seamlessly integrate active filter functions into meshed inverters to realize active filtering of nonlinear loads by multiplexing inverters. This method can be executed by an active filter function multiplexing control device of a meshed inverter. The active filter function multiplexing control device of a meshed inverter can be implemented in the form of hardware and / or software. The active filter function multiplexing control device of a meshed inverter can be configured in an electronic device. Figure 2 As shown, the present embodiment 1 provides a method for controlling active filtering function reuse of a grid-connected inverter, which specifically includes the following steps:

[0047] S110, obtaining real-time operating parameters of the inverter; wherein the real-time operating parameters at least include: grid-side current, grid-connection point voltage, and capacitor voltage of the filter capacitor.

[0048] In the embodiment of the present invention, the real-time operating parameters of the inverter can be obtained through some pre-configured power grid data acquisition devices, wherein the real-time operating parameters can at least include: the grid-side current i2, the grid-connected point voltage u pcc And the capacitance voltage u of the filter capacitor c Specifically, the grid-side current i2 can be collected by a current collection device such as a current transformer, and the grid-connection point voltage u can be collected by a voltage collection device such as a voltage transformer. pcc And the capacitance voltage u of the filter capacitor c It is understandable that, in addition to using the above-mentioned current transformer and voltage transformer, this embodiment can also collect the current and voltage at each point on the grid-connected line through other automatic collection terminals, that is, this embodiment does not specifically limit the way of collecting current and voltage.

[0049] S120: Determine a reference voltage corresponding to the inverter according to the grid-side current, capacitor voltage and preset operating parameters.

[0050] The preset working parameters may include at least: preset active power P set and preset reactive power Q set , preset active power P set Indicates the given value of the inverter output active power, that is, the active power rating; preset reactive power Q set Indicates the given value of the inverter output reactive power, that is, the reactive power rating. The reference voltage can refer to a voltage command generated by any grid-forming algorithm based on the grid-side current, capacitor voltage and preset operating parameters.

[0051] like Figure 1 As shown, in the embodiment of the present invention, the preset working parameters and the collected grid-side current i2 and capacitor voltage uc Input to the reference voltage calculation module, and determine the reference voltage u corresponding to the inverter through the reference voltage calculation module ref ; Wherein, the preset working parameters may at least include: preset active power P set and preset reactive power Q set Specifically, the collected grid-side current i2 and capacitor voltage u c Determine the instantaneous active power P output by the inverter out and instantaneous reactive power Q out , and then the instantaneous active power P is controlled by the power controller out and instantaneous reactive power Q out , preset active power P set and preset reactive power Q set Calculate and get the reference voltage u ref Among them, the instantaneous active power, instantaneous reactive power and the specific algorithm of the power controller can refer to the existing technology, and this embodiment will not be repeated here.

[0052] S130, respectively extracting harmonic components corresponding to the capacitor voltage and the grid-connected point voltage to obtain corresponding capacitor voltage harmonic components and grid-connected point voltage harmonic components.

[0053] Among them, the capacitor voltage harmonic component u c.h And the grid-connected voltage harmonic component u pcc.h , can refer to the capacitor voltage u c and grid voltage u pcc The harmonic components obtained after removing the fundamental component.

[0054] like Figure 1 As shown, in the embodiment of the present invention, the collected capacitor voltage u c and grid voltage u pcc After being respectively input into the voltage harmonic component extraction module, the voltage harmonic component extraction module can first extract the fundamental component in the original voltage signal, and then make a difference between the original voltage signal and the corresponding fundamental component to obtain the corresponding voltage harmonic component. Among them, the voltage harmonic component extraction module can use a complex vector filter, such as a first-order complex vector filter, a second-order complex vector filter, etc., which is not specifically limited in this embodiment.

[0055] S140. Determine a reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component.

[0056] The reference voltage harmonic component may refer to the harmonic component of the reference voltage obtained after performing harmonic compensation calculation on the capacitor voltage harmonic component and the grid connection point voltage harmonic component.

[0057] like Figure 1 As shown, in the embodiment of the present invention, the capacitor voltage harmonic component u determined in S130 can be c.h And the grid-connected voltage harmonic component u pcc.h Input into the harmonic compensation module to obtain the corresponding reference voltage harmonic component u for compensating the harmonic current generated by the local nonlinear load ref.h The harmonic compensation module may be in the form of, but not limited to, a harmonic compensation circuit, a harmonic compensation formula, a harmonic compensation model, and the like.

[0058] By determining the harmonic component of the reference voltage for harmonic compensation, the harmonic impedance of the inverter can be equivalently increased, so that the harmonic current generated by the local nonlinear load can be compensated, the harmonic current in the inverter output current is reduced, and the power quality of the grid is improved.

[0059] S150, determining a target control parameter according to the capacitor voltage, the reference voltage, and the harmonic component of the reference voltage.

[0060] like Figure 1 As shown, in the embodiment of the present invention, the capacitor voltage u c , reference voltage u ref and the reference voltage harmonic component u ref.h The input is sent to the voltage and current closed-loop control module, and the corresponding target control parameter is output through the dual control algorithm of the voltage outer loop and the current inner loop; wherein the target control parameter can be understood as a parameter for controlling the duty cycle of the inverter.

[0061] S160: Control the switching devices of the inverter according to the target control parameters.

[0062] Among them, the switching device may refer to a power control switch used to convert direct current into alternating current. Its function is to control the flow direction and size of electric energy in the inverter output circuit. The switching device may be a switching tube, such as an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), etc.

[0063] like Figure 1 As shown, in the embodiment of the present invention, the above-determined target control parameters can be input into the PWM modulation module, so that the PWM modulation module outputs a PWM modulation signal corresponding to the duty cycle, and then the PWM modulation signal is used to control the conduction state of the switching device of the inverter to achieve the capacitor voltage u output by the inverter c The amplitude and phase are the same as the given reference voltage uref Be consistent.

[0064] The technical solution of the embodiment of the present invention respectively extracts the harmonic components corresponding to the capacitor voltage and the grid-connected point voltage of the inverter, and then uses the harmonic components of the two to determine the corresponding reference voltage harmonic components, and then determines the target control parameters according to the capacitor voltage, the reference voltage and the reference voltage harmonic components, and then controls the switching devices of the inverter according to the target control parameters, thereby solving the problem of multiplexing the active filtering function on the meshing control architecture, realizing the seamless integration of the active filtering function in the existing meshing inverter topology structure, equivalently improving the harmonic impedance of the inverter, and then realizing the compensation of the harmonic current generated by the local nonlinear load, reducing the harmonic current in the inverter output current, thereby improving the power quality of the power grid, and having a wide range of application scenarios.

[0065] Embodiment 2

[0066] Figure 3 The topological structure diagram of an active filter function multiplexing control system of a grid-type inverter provided in the second embodiment of the present invention is shown in FIG. Figure 3 As shown, the active filtering function multiplexing control system of this embodiment is a further optimization based on the above active filtering function multiplexing control system. Specifically, the reference voltage calculation module includes:

[0067] The output power calculation unit is used to calculate the power of the grid according to the collected grid-side current i2 and capacitor voltage u c Determine the instantaneous active power P output by the inverter out and instantaneous reactive power Q out ;

[0068] The power control algorithm unit is used to control the instantaneous active power P according to any network-building algorithm. out and instantaneous reactive power Q out , preset active power P set and preset reactive power Q set Calculate and get the reference voltage u ref The corresponding reference voltage phase θ and reference voltage amplitude E;

[0069] The voltage command setting unit is used to synthesize the voltage according to the reference voltage phase θ and the reference voltage amplitude E to obtain the reference voltage u in the three-phase coordinate system. ref .

[0070] Based on the above active filtering function multiplexing control system, Figure 4 The flowchart of the active filter function multiplexing control method of a grid-type inverter provided in the second embodiment of the present invention is further optimized and expanded based on the above-mentioned implementation mode, and can be combined with various optional technical solutions in the above-mentioned implementation mode. Figure 4As shown, the second embodiment provides a method for controlling active filtering function reuse of a grid-connected inverter, which specifically includes the following steps:

[0071] S210, obtaining real-time operating parameters of the inverter; wherein the real-time operating parameters at least include: grid-side current, grid-connection point voltage, and capacitor voltage of the filter capacitor.

[0072] S220 , performing Clark transformation on the grid-side current and capacitor voltage in the three-phase coordinate system to obtain a target grid-side current and a target capacitor voltage in the two-phase coordinate system.

[0073] Among them, Clark transformation is a commonly used coordinate transformation method in three-phase power systems, which can convert electrical quantities in a three-phase stationary coordinate system (abc coordinate system) into a two-phase stationary coordinate system (αβ coordinate system). The target grid-side current and target capacitor voltage can be understood as the grid-side current and capacitor voltage converted from the three-phase coordinate system to the two-phase coordinate system, respectively.

[0074] like Figure 3 As shown, in the embodiment of the present invention, the collected grid-side current i2 and capacitor voltage u c Input to the output power calculation unit, and use Clark transformation to convert the grid-side current i2 and capacitor voltage u in the three-phase coordinate system c , converted into the target grid-side current and target capacitor voltage in the two-phase coordinate system, where the target grid-side current includes the α component i of the grid-side current i2 2α and β component i 2β ; The target capacitor voltage includes the capacitor voltage u c The α component u cα and the β component u cβ .

[0075] S230 . Perform power calculation based on the target grid-side current and the target capacitor voltage to obtain instantaneous active power and instantaneous reactive power output by the inverter.

[0076] In the embodiment of the present invention, the instantaneous active power P output by the inverter can be determined using the following formula: out and instantaneous reactive power Q out :

[0077] P out =u cα i 2α +u cβ i 2β

[0078] Q out =u cβ i 2α -u cα i 2β

[0079] S240, based on the preset active power and the preset reactive power and through any kind of meshing algorithm, determine the reference voltage phase and the reference voltage amplitude corresponding to the instantaneous active power and the instantaneous reactive power, and synthesize the reference voltage phase and the reference voltage amplitude into a reference voltage.

[0080] The meshing algorithm in this embodiment includes at least one of the following: a droop control algorithm, a matching control algorithm, a virtual synchronous generator simulation algorithm, etc. Exemplarily, the corresponding reference voltage can be determined by simulating the rotor motion and excitation characteristics of the synchronous generator.

[0081] like Figure 3 As shown, in the embodiment of the present invention, the preset active power P set and preset reactive power Q set , and the instantaneous active power P determined above out and instantaneous reactive power Q out The two are input to the power control algorithm unit to determine the corresponding reference voltage phase θ and reference voltage amplitude E. The power control algorithm unit specifically adopts the following model:

[0082]

[0083] In the formula, ω and ω n are the virtual angular frequency and the rated angular frequency respectively; J is the virtual inertia of the power control algorithm unit. By using parameter J, the power control algorithm unit can show the frequency support characteristics of the network; D is the damping coefficient of the power control algorithm unit; T m and T e They are shown as follows:

[0084]

[0085] Where P e That is the instantaneous active power P mentioned above out In order to simulate the active power-frequency droop characteristics, P m It can be expressed by the following formula:

[0086] P m =P set +K f (ω n -ω)

[0087] In the formula, K f is the adjustment coefficient.

[0088] In order to enable the power control algorithm unit to simulate the reactive power-voltage droop characteristics, the reactive power command Q m As shown below:

[0089]

[0090] Where U n is the effective value of the rated phase voltage; U is the effective value of the capacitor phase voltage; K v is the voltage regulation coefficient.

[0091] In order to make the reactive power Q output by the power control algorithm unit e , that is, the instantaneous reactive power Q determined above out , according to the reactive power instruction Q m Change, let the reactive power deviation be integrated to obtain the amplitude E of the reference voltage output by the power control algorithm unit, as shown in the following formula:

[0092]

[0093] In summary, the reference voltage phase θ and the reference voltage amplitude E can be determined.

[0094] After that, the reference voltage phase θ and the reference voltage amplitude E are input into the voltage command given unit for voltage synthesis, thereby obtaining the reference voltage u in the three-phase coordinate system. ref ,Right now:

[0095] u refa = Esin(θ)

[0096]

[0097] In the formula, u refa 、u refb and u refc Respectively represent the reference voltage u ref The abc components of .

[0098] S250 , calling a pre-configured first-order complex vector filter to extract the fundamental wave components corresponding to the grid connection point voltage and the capacitor voltage respectively, to obtain the corresponding capacitor voltage fundamental wave component and grid connection point voltage fundamental wave component.

[0099] like Figure 3 As shown, in the embodiment of the present invention, the collected capacitor voltage u c and grid voltage u pcc The voltage harmonic component extraction module is used to extract the capacitor voltage u respectively by using the built-in first-order complex vector filter with a gain of 1 and no phase change at the base frequency f0. c and grid voltage u pcc Perform signal processing to extract the corresponding fundamental component, thereby obtaining the corresponding capacitor voltage fundamental component and the fundamental component of the grid-connected point voltage Among them, the transfer function H(s) of the first-order complex vector filter is expressed as follows:

[0100]

[0101] In the formula, ω c represents the cut-off angular frequency, which can be set equal to 0.707ω0; ω0=2πf0 represents the fundamental positive sequence angular frequency of the grid voltage, and f0 is 50Hz; s represents the Laplace operator; j represents the imaginary unit.

[0102] S260: taking the difference between the capacitor voltage and the fundamental component of the capacitor voltage as the capacitor voltage harmonic component, and taking the difference between the grid connection point voltage and the fundamental component of the grid connection point voltage as the grid connection point voltage harmonic component.

[0103] In the embodiment of the present invention, since the original signal can be represented as the superposition of the corresponding fundamental component and the harmonic component, the capacitor voltage harmonic component can be determined. Harmonic components of grid-connected point voltage

[0104] Further, based on the above-mentioned embodiment of the invention, the transfer function T(s) of the voltage harmonic component extraction module can be expressed as follows:

[0105]

[0106] S270. Determine the product of the harmonic component of the grid connection point voltage and the first preset harmonic compensation control parameter, and record it as the first harmonic compensation amount.

[0107] Figure 5 This is a schematic diagram of the structure of the harmonic compensation module provided in the second embodiment of the present invention. Figure 5 As shown, the harmonic compensation module includes two operational amplifiers whose output signal amplitude is proportional to the input signal amplitude: the first operational amplifier and the second operational amplifier can convert the grid voltage harmonic component u pcc.h Input to the first operational amplifier to obtain the grid voltage harmonic component u pcc.h The product of the first preset harmonic compensation control parameter a is the first harmonic compensation value a·u pcc.h .

[0108] S280: Determine the product of the capacitor voltage harmonic component and the second preset harmonic compensation control parameter, and record it as the second harmonic compensation amount.

[0109] Figure 5 As shown, in the embodiment of the present invention, the capacitor voltage harmonic component u c.h Input to the second operational amplifier to obtain the capacitor voltage harmonic component u c.hThe product of the second preset harmonic compensation control parameter b is the second harmonic compensation amount b·u c.h .

[0110] S290: Taking the difference between the first harmonic compensation amount and the second harmonic compensation amount as a reference voltage harmonic component.

[0111] In the embodiment of the present invention, based on the first harmonic compensation amount a·u pcc.h and the second harmonic compensation b·u c.h , the reference voltage harmonic component u can be determined ref.h as follows:

[0112] u ref.h =a·u pcc.h -b·u c.h

[0113] Further, based on the above-mentioned embodiment of the invention, the second preset harmonic compensation control parameter b can be set to a-1, that is, the reference voltage harmonic component u ref.h =a·u pcc.h -(a-1)·u c.h Within a certain range, the larger the value of a is set, the more obvious the compensation effect on the harmonic current generated by the local nonlinear load is. However, if the value of a is too large, it will cause system instability. Therefore, it is necessary to choose a reasonable value based on the actual situation.

[0114] The harmonic compensation module of this embodiment can equivalently improve the harmonic impedance of the inverter, thereby achieving compensation for the harmonic current generated by the local nonlinear load, reducing the harmonic current in the inverter output current, and thus improving the power quality of the power grid.

[0115] S2100 , perform voltage outer loop control based on capacitor voltage, reference voltage and reference voltage harmonic components to obtain reference current.

[0116] Figure 6 This is a schematic diagram of the structure of the voltage and current closed-loop control module provided in the second embodiment of the present invention. Figure 6 As shown, the voltage and current closed-loop control module is used to realize the capacitor voltage u output by the inverter c The amplitude and phase are the same as the given reference voltage u ref Keep consistent, specifically including the following three parts: voltage loop controller, voltage resonant controller and current loop controller. pwm is the equivalent transfer function of the inherent delay link of the system; G i is the transfer function of the current loop controller; G u is the transfer function of the voltage loop controller; G Ru is the transfer function of the voltage resonant controller.

[0117] Specifically, the voltage loop controller may adopt a proportional resonant controller for controlling the capacitor voltage u c , reference voltage u ref and the reference voltage harmonic component u ref.h , determine the corresponding reference current i ref The voltage controller is also used to adjust the reference voltage u ref , the capacitor voltage u of the inverter output c Perform voltage outer loop control and track the reference voltage u ref At the same time, a voltage resonant controller connected in parallel with the voltage controller is introduced in the voltage outer loop control to track the reference voltage harmonic component u ref.h , and the transfer function of the voltage resonant controller G Ru It is expressed as follows:

[0118]

[0119] Where h is the resonant frequency; k is ru is the gain coefficient of the voltage resonance controller; ω b is the voltage resonant controller bandwidth.

[0120] In order to ensure that the system is sensitive to the reference voltage harmonic component u ref.h The voltage resonance controller is introduced into the voltage outer loop control to improve the reference voltage harmonic component u by using the high gain characteristic of the voltage resonance controller at the harmonic frequency. ref.h The control performance enables the system to effectively track the reference voltage harmonic component u ref.h , thereby effectively improving the quality of grid-connected current.

[0121] S2110. Perform current inner loop control based on the reference current to obtain target control parameters.

[0122] like Figure 6 As shown, in the embodiment of the present invention, the current loop controller may adopt a proportional controller for adjusting the current loop according to the reference current i ref Perform current inner loop control and track the reference current i ref , and outputs the corresponding target control parameter; wherein the target control parameter can be understood as a parameter for controlling the duty cycle of the inverter.

[0123] S2120, determining a pulse width modulation signal after the target control parameter is modulated by the space vector, and controlling the conduction state of the switching device according to the pulse width modulation signal.

[0124] Among them, space vector modulation (Space Vector Pulse Width Modulation, SVPWM) is a common modulation method in three-phase inverter circuits. It controls the working conduction state of the inverter's switching devices by generating a pulse width modulation signal (PWM modulation signal), thereby controlling the inverter output and a given reference voltage u ref The capacitor voltage u remains consistent in both amplitude and phase c .

[0125] like Figure 3 As shown, in the embodiment of the present invention, the above-determined target control parameters can be input into the PWM modulation module, and the corresponding PWM modulation signals can be generated after space vector modulation, so as to realize the control of the switching devices of the inverter, such as the switch tube. It can be understood that the duty cycle of the PWM modulation signals corresponding to different target control parameters is different, and the switching devices of the inverter are controlled to be turned on or off by the PWM modulation signals with different duty cycles, so as to realize the capacitor voltage u output by the inverter c The amplitude and phase are the same as the given reference voltage u ref Be consistent.

[0126] The technical solution of the embodiment of the present invention, by respectively extracting the harmonic components corresponding to the capacitor voltage and the grid-connected point voltage of the inverter, and then using the harmonic components of the two to determine the corresponding reference voltage harmonic components, the harmonic impedance of the inverter is equivalently improved, thereby realizing compensation for the harmonic current generated by the local nonlinear load; the corresponding target control parameters are determined by dual control of the voltage outer loop and the current inner loop, and then the conduction state of the switching device of the inverter is controlled according to the target control parameters, thereby realizing seamless integration of active filtering function in the existing grid-type inverter topology structure, and realizing on-site absorption of nonlinear load harmonics in distributed distribution network stations and power supply areas, solving the problem of poor harmonic suppression capability in the prior art, reducing the harmonic current in the inverter output current, thereby improving the power quality of the power grid; at the same time, it has a wide range of application scenarios, and can contain active filtering capabilities in each distributed energy power supply area and station, and use distributed inverters to control distributed nonlinear load harmonic problems.

[0127] Embodiment 3

[0128] Figure 7 This is a schematic diagram of the structure of an active filter function multiplexing control device for a grid-type inverter provided in the third embodiment of the present invention. Figure 7 As shown, the device comprises:

[0129] The parameter acquisition module 31 is used to acquire the real-time operating parameters of the inverter; wherein the real-time operating parameters at least include: grid-side current, grid-connection point voltage and capacitor voltage of the filter capacitor;

[0130] A reference voltage determination module 32, used to determine a reference voltage corresponding to the inverter according to the grid-side current, capacitor voltage and preset operating parameters;

[0131] The harmonic extraction module 33 is used to extract the harmonic components corresponding to the capacitor voltage and the grid connection point voltage respectively, and obtain the corresponding capacitor voltage harmonic components and grid connection point voltage harmonic components;

[0132] The harmonic compensation module 34 is used to determine the reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component;

[0133] A target control parameter determination module 35, for determining a target control parameter according to the capacitor voltage, the reference voltage and the harmonic component of the reference voltage;

[0134] The inverter control module 36 is used to control the switching devices of the inverter according to the target control parameters.

[0135] The technical solution of the embodiment of the present invention respectively extracts the harmonic components corresponding to the capacitor voltage and the grid-connected point voltage of the inverter, and then uses the harmonic components of the two to determine the corresponding reference voltage harmonic components, and then determines the target control parameters according to the capacitor voltage, the reference voltage and the reference voltage harmonic components, and then controls the switching devices of the inverter according to the target control parameters, thereby solving the problem of multiplexing the active filtering function on the meshing control architecture, realizing the seamless integration of the active filtering function in the existing meshing inverter topology structure, equivalently improving the harmonic impedance of the inverter, and then realizing the compensation of the harmonic current generated by the local nonlinear load, reducing the harmonic current in the inverter output current, thereby improving the power quality of the power grid, and having a wide range of application scenarios.

[0136] Further, based on the above-mentioned embodiment of the invention, the reference voltage determination module 32 includes:

[0137] A coordinate conversion unit, used for performing Clark transformation on the grid-side current and capacitor voltage in the three-phase coordinate system to obtain a target grid-side current and target capacitor voltage in the two-phase coordinate system;

[0138] A power calculation unit, used to perform power calculation based on a target grid-side current and a target capacitor voltage to obtain instantaneous active power and instantaneous reactive power output by the inverter;

[0139] The reference voltage determination unit is used to determine the reference voltage phase and reference voltage amplitude corresponding to the instantaneous active power and instantaneous reactive power based on the preset active power and preset reactive power and through any meshing algorithm, and synthesize the reference voltage phase and the reference voltage amplitude into a reference voltage.

[0140] Further, based on the above-mentioned embodiment of the invention, the harmonic extraction module 33 includes:

[0141] A fundamental component extraction unit is used to call a pre-configured first-order complex vector filter to extract the fundamental components corresponding to the grid connection point voltage and the capacitor voltage, respectively, to obtain the corresponding capacitor voltage fundamental component and grid connection point voltage fundamental component;

[0142] The harmonic component determination unit is used to take the difference between the capacitor voltage and the capacitor voltage fundamental component as the capacitor voltage harmonic component, and to take the difference between the grid connection point voltage and the grid connection point voltage fundamental component as the grid connection point voltage harmonic component.

[0143] Further, based on the above-mentioned embodiment of the invention, the harmonic compensation module 34 includes:

[0144] A first data processing unit is used to determine the product of the harmonic component of the grid connection point voltage and the first preset harmonic compensation control parameter, which is recorded as the first harmonic compensation amount;

[0145] A second data processing unit is used to determine the product of the capacitor voltage harmonic component and the second preset harmonic compensation control parameter, which is recorded as the second harmonic compensation amount;

[0146] The reference voltage harmonic component determination unit is used to use the difference between the first harmonic compensation amount and the second harmonic compensation amount as the reference voltage harmonic component.

[0147] Further, based on the above-mentioned embodiment of the invention, the target control parameter determination module 35 includes:

[0148] A reference current determination unit, used for performing voltage outer loop control based on the capacitor voltage, the reference voltage and the reference voltage harmonic component to obtain a reference current;

[0149] The target control parameter determination unit is used to perform current inner loop control based on the reference current to obtain the target control parameter.

[0150] Further, based on the above-mentioned embodiment of the invention, the inverter control module 36 includes:

[0151] The inverter control unit is used to determine the pulse width modulation signal after the target control parameter is modulated by the space vector, and control the conduction state of the switching device according to the pulse width modulation signal.

[0152] Further, based on the above-mentioned embodiment of the invention, the transfer function of the first-order complex vector filter is expressed as:

[0153]

[0154] Among them, ω crepresents the cut-off angular frequency; ω0 represents the fundamental positive sequence angular frequency of the grid voltage; s represents the Laplace operator; j represents the imaginary unit.

[0155] The active filter function multiplexing control device of the grid-type inverter provided in the embodiment of the present invention can execute the active filter function multiplexing control method of the grid-type inverter provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0156] Embodiment 4

[0157] Figure 8 A schematic diagram of the structure of an electronic device 40 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0158] like Figure 8 As shown, the electronic device 40 includes at least one processor 41, and a memory connected to the at least one processor 41, such as a read-only memory (ROM) 42, a random access memory (RAM) 43, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 41 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 42 or the computer program loaded from the storage unit 48 to the random access memory (RAM) 43. In the RAM 43, various programs and data required for the operation of the electronic device 50 can also be stored. The processor 41, the ROM 42, and the RAM 43 are connected to each other through a bus 44. An input / output (I / O) interface 45 is also connected to the bus 44.

[0159] A number of components in the electronic device 40 are connected to the I / O interface 45, including: an input unit 46, such as a keyboard, a mouse, etc.; an output unit 47, such as various types of displays, speakers, etc.; a storage unit 48, such as a disk, an optical disk, etc.; and a communication unit 49, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 49 allows the electronic device 40 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0160] The processor 41 may be a variety of general and / or dedicated processing components with processing and computing capabilities. Some examples of the processor 41 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The processor 41 executes the various methods and processes described above, such as the active filter function multiplexing control method of the grid-type inverter.

[0161] In some embodiments, the active filter function multiplexing control method of the grid-type inverter can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 48. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 40 via the ROM 42 and / or the communication unit 49. When the computer program is loaded into the RAM 43 and executed by the processor 41, one or more steps of the active filter function multiplexing control method of the grid-type inverter described above can be performed. Alternatively, in other embodiments, the processor 41 can be configured to execute the active filter function multiplexing control method of the grid-type inverter by any other appropriate means (for example, by means of firmware).

[0162] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0163] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0164] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0165] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0166] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0167] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0168] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0169] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for multiplexing active filter functions of a grid-connected inverter, characterized in that: The method comprises: Acquire real-time operating parameters of the inverter; wherein the real-time operating parameters include at least: grid-side current, grid-connection point voltage, and capacitor voltage of the filter capacitor; Determining a reference voltage corresponding to the inverter according to the grid-side current, the capacitor voltage and preset operating parameters; Extracting the harmonic components corresponding to the capacitor voltage and the grid-connection point voltage respectively, and obtaining the corresponding capacitor voltage harmonic components and grid-connection point voltage harmonic components; Determine a reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component; determining a target control parameter according to the capacitor voltage, the reference voltage and the reference voltage harmonic component; The switching device of the inverter is controlled according to the target control parameter.

2. The method according to claim 1, characterized in that The determining, according to the grid-side current, the capacitor voltage and preset operating parameters, a reference voltage corresponding to the inverter includes: Performing Clark transformation on the grid-side current and the capacitor voltage in the three-phase coordinate system to obtain a target grid-side current and a target capacitor voltage in the two-phase coordinate system; Performing power calculation based on the target grid-side current and the target capacitor voltage to obtain instantaneous active power and instantaneous reactive power output by the inverter; Based on the preset active power and the preset reactive power and through any meshing algorithm, the reference voltage phase and the reference voltage amplitude corresponding to the instantaneous active power and the instantaneous reactive power are determined, and the reference voltage phase and the reference voltage amplitude are synthesized into the reference voltage.

3. The method according to claim 1, characterized in that The extracting the harmonic components corresponding to the capacitor voltage and the grid connection point voltage respectively to obtain the corresponding capacitor voltage harmonic components and grid connection point voltage harmonic components includes: Calling a pre-configured first-order complex vector filter to respectively extract the fundamental wave components corresponding to the grid connection point voltage and the capacitor voltage, and obtaining the corresponding capacitor voltage fundamental wave component and grid connection point voltage fundamental wave component; The difference between the capacitor voltage and the capacitor voltage fundamental component is used as the capacitor voltage harmonic component, and the difference between the grid point voltage and the grid point voltage fundamental component is used as the grid point voltage harmonic component.

4. The method according to claim 1, characterized in that: The determining of the reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component comprises: Determine the product of the harmonic component of the grid connection point voltage and a first preset harmonic compensation control parameter, recorded as a first harmonic compensation amount; Determine the product of the capacitor voltage harmonic component and a second preset harmonic compensation control parameter, recorded as a second harmonic compensation amount; The difference between the first harmonic compensation amount and the second harmonic compensation amount is used as the reference voltage harmonic component.

5. The method according to claim 1, characterized in that: The determining of the target control parameter according to the capacitor voltage, the reference voltage and the reference voltage harmonic component comprises: Perform voltage outer loop control based on the capacitor voltage, the reference voltage and the reference voltage harmonic component to obtain a reference current; A current inner loop control is performed based on the reference current to obtain the target control parameter.

6. The method according to claim 1, characterized in that The controlling the switching device of the inverter according to the target control parameter includes: A pulse width modulation signal after space vector modulation of the target control parameter is determined, and the conduction state of the switching device is controlled according to the pulse width modulation signal.

7. The method according to claim 3, characterized in that The transfer function of the first-order complex vector filter is expressed as: Among them, ω c represents the cut-off angular frequency; ω0 represents the fundamental positive sequence angular frequency of the grid voltage; s represents the Laplace operator; j represents the imaginary unit.

8. An active filter function multiplexing control device for a grid-type inverter, characterized in that: The device comprises: A parameter acquisition module, used to acquire real-time operating parameters of the inverter; wherein the real-time operating parameters at least include: grid-side current, grid-connection point voltage and capacitor voltage of the filter capacitor; A reference voltage determination module, used to determine a reference voltage corresponding to the inverter according to the grid-side current, the capacitor voltage and preset operating parameters; A harmonic extraction module, used to extract the harmonic components corresponding to the capacitor voltage and the grid connection point voltage respectively, to obtain the corresponding capacitor voltage harmonic components and grid connection point voltage harmonic components; A harmonic compensation module, used to determine a reference voltage harmonic component according to the capacitor voltage harmonic component and the grid connection point voltage harmonic component; a target control parameter determination module, configured to determine a target control parameter according to the capacitor voltage, the reference voltage and the reference voltage harmonic component; An inverter control module is used to control the switching device of the inverter according to the target control parameter.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the active filter function multiplexing control method of the grid-connected inverter described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the active filter function multiplexing control method of a grid-connected inverter according to any one of claims 1 to 7 when executed.

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