CN115603335A - Grid-connected inverter integrating active damping function and control method - Google Patents
Grid-connected inverter integrating active damping function and control method Download PDFInfo
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- H—ELECTRICITY
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract
The invention discloses a grid-connected inverter control method integrated with an active damping function, and aims to solve the problems that grid-connected current contains a large amount of harmonic waves and even is unstable due to mutual coupling of a grid-connected inverter system and grid impedance under the condition of weak grid. The grid-connected inverter integrates the function of the active damper, realizes inversion grid connection, solves the resonance problem under a weak power grid and achieves the purpose of one machine with multiple purposes; a self-adaptive virtual resistance method is provided, and power loss is reduced while harmonic resonance of the grid-connected inverter is effectively inhibited.
Description
Technical Field
The invention relates to a grid-connected inverter integrated with an active damping function and a control method, and belongs to the technical field of power electronics.
Background
Under a weak power grid, the grid-connected inverter has the stability problem of harmonic resonance in a wide frequency band, such as distortion of grid-connected current and oscillation of grid-connected power, and even the whole inverter can not stably operate and is cut off from the power grid by a protection device in a serious condition. The problem is influenced by software and hardware of the inverter, power grid impedance and the number of parallel inverters, and challenges are brought to safe and stable operation of a grid-connected inverter system. When a plurality of inverters exist in a grid-connected system, each inverter in the grid-connected inverter system needs to be upgraded or replaced according to the optimization scheme of the control strategy of the grid-connected inverter, so that the problems of overlarge cost, poor universality and the like are caused. From a system level, the damping may be performed at a Point of Common Coupling (PCC) in parallel with an impedance that may be simulated by a power electronic converter, the corresponding power electronic system being called an active damping device or impedance adapter. The active damper and the grid-connected converter exist as two independent devices, the specific research of integrating the function of the active damper on the grid-connected converter does not exist, and the main problem of integrating the function of the active damper on the grid-connected converter is the difficult problem that the capacity and the control of the two are mutually restricted.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a grid-connected inverter integrating an active damping function and a control method, which are used for solving the resonance problem under a weak power grid while realizing inversion grid connection.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a grid-connected inverter control method integrating an active damping function, which includes:
voltage v of common coupling point pcc Is sent to a wave trap G NA (s) filtering out the PCC voltage v pcc To obtain a resonance voltage v at the point of common coupling pcch ；
According to the resonance voltage v pcch And adaptively adjusting the obtained virtual resistance R v Calculating to obtain a harmonic current reference value i absorbed by the active damper from the power grid h_ref ；
According to the voltage v of the point of common coupling pcc The fundamental component of the active damper calculates a fundamental current reference value i fed back to the power grid by the active damper 1_ref ；
The fundamental current reference value i 1_ref Feeding into harmonic current reference compensation link G cA (s) for the harmonic current reference value i h_ref Performing harmonic current reference compensation;
compensating the harmonic current reference link G cA (s) output current and fundamental current reference value i 1_ref Subtracting the current I from the collected current I at the port of the active damper B Subtracting to obtain a first error signal;
feeding said first error signal into a current regulator G iA (s) coupling said current regulator G iA Subtracting the filter capacitor current feedback signal after the output signal of(s) is inverted to obtain the modulation voltage v MA (ii) a The filter capacitor is connected between an inverter side inductor and a grid side inductor of the grid-connected inverter;
applying the modulation voltage v MA Sending the driving signal into a PWM modulator to generate a driving signal for controlling a switching tube in the grid-connected inverter。
With reference to the first aspect, further, the dummy resistance R v Realizing self-adaptive adjustment based on the RBF network;
the RBF network uses a virtual resistor R v The output of the self-corrector and the resonance voltage v pcch As an input quantity, an ideal tracking value is acquired by the recognizer.
With reference to the first aspect, further, the output radial basis value, the output weight, the basis width vector and the node vector of the RBF network are updated in real time by a gradient descent method to obtain the characteristic resonant voltage v pcch And sending the Jacobian matrix of the sensitivity information input by the RBF network to an active damper for correcting and calculating system parameters.
With reference to the first aspect, further, the output of the active damper is:
in the formula: v. of pcch (k) For the resonant voltage v at the kth iteration pcch A value of (d); r v Is a virtual resistance; e.g. of the type c (k) For the k-th iteration error,
for the resonant voltage v at the kth iteration pcch Reference value of v pcch (k-1) is the resonant voltage v at the k-1 th iteration pcch A value of (d); e.g. of the type c And (k-1) is the (k-1) th iteration error.
In combination with the first aspect, further, the wave trap G NA (s) is expressed as:
in the formula: omega 0 ＝2πf 0 Is a radicalWave angular frequency, Q is the quality factor, f 0 Is the grid frequency.
With reference to the first aspect, further, the harmonic current reference compensation element G cA (s) is represented by
In the formula: k pA Is the proportionality coefficient of the current regulator; omega iA Is the resonance term bandwidth; g dA (s) controlling the delay; l is 1B An inverter side inductor of the grid-connected inverter; l is 2B Is a net side inductor.
With reference to the first aspect, further, the current regulator G iA (s) is expressed as:
in the formula, K pA And K rA The proportionality coefficient and the resonance coefficient of the current regulator are respectively; omega iA Is the resonance term bandwidth; omega 0 ＝2πf 0 Is the fundamental angular frequency, f 0 Is the grid frequency.
In combination with the first aspect, further according to the pcc voltage v pcc The fundamental component of the active damper calculates a fundamental current reference value i fed back to the power grid by the active damper 1_ref The method comprises the following steps:
detecting the pcc voltage v using a phase-locked loop pcc The phase of the fundamental component of (a);
the voltage v of the common coupling point pcc Of the phase of the fundamental component and the grid-connected current reference value
Multiplying, namely the product is the fundamental current reference value i 1_ref 。
With reference to the first aspect, further, the filter capacitor current feedback signal is obtained by multiplying the collected filter capacitor current by a filter capacitor current feedback coefficient and then calculating.
In a second aspect, the present invention provides a grid-connected inverter integrated with an active damping function, including:
a wave trap: for filtering out the voltage v of the point of common coupling pcc To obtain a resonant voltage v at the point of common coupling pcch ；
Virtual resistance adaptive regulator: self-adaptive adjustment of virtual resistance R according to stability of grid-connected inverter v And according to the resonance voltage v output by the wave trap pcch Calculating and obtaining a harmonic current reference value i absorbed by the active damper from a power grid h_ref ；
A phase-locked loop: for detecting the voltage v of the point of common coupling pcc To calculate the fundamental current reference value i of the active damper feeding back to the power grid 1_ref ；
And a harmonic current reference compensation step: for reference value i of the harmonic current h_ref Compensation is carried out;
and an error calculation step: the output current of the harmonic current reference compensation link is compared with a fundamental current reference value i 1_ref Subtracting the current I from the collected current I at the port of the active damper B Subtracting to obtain a first error signal;
current regulator: for current regulating the first error signal;
a modulation voltage generation link: is used for subtracting the filter capacitor current feedback signal after inverting the output signal of the current regulator to obtain a modulation voltage v MA (ii) a The filter capacitor is connected between an inverter side inductor and a grid side inductor of the grid-connected inverter;
a PWM modulator: for varying the modulation voltage v MA And generating a driving signal for controlling a switching tube in the grid-connected inverter.
Compared with the prior art, the invention has the following beneficial effects:
the grid-connected inverter is integrated with an active damper function, so that the problem of resonance under a weak power grid is solved while inversion grid connection is realized, and the purpose of one machine with multiple purposes is achieved; the virtual resistance value is self-adaptively adjusted according to the stability of the grid-connected inverter, and the power loss is reduced while the harmonic resonance of the grid-connected inverter is effectively inhibited.
Drawings
Fig. 1 is a schematic block diagram of a grid-connected inverter integrated with an active damping function according to an embodiment of the present invention;
FIG. 2 is a block diagram of the control scheme of the adaptive virtual resistance regulator of FIG. 1;
FIG. 3 is a waveform diagram showing the simulation of the output current of the grid-connected inverter before and after the active damper is incorporated;
FIG. 4 is a simulation waveform diagram of the grid-connected inverter PCC voltage before and after the active damper is incorporated;
FIG. 5 is a simulated waveform diagram of the output current of the active damper after the resonance is effectively suppressed;
FIG. 6 is a waveform diagram of the simulation of the output resonant current of the active damper when the adaptive virtual resistance method is used;
fig. 7 is a waveform diagram of an output resonant current simulation of an active damper using a 10 Ω fixed resistor.
Detailed Description
The technical solutions of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments, and it should be understood that the specific features in the embodiments and examples are described in detail in the technical solutions of the present invention, but not limited to the technical solutions of the present invention, and the technical features in the embodiments and examples may be combined with each other without conflict.
The first embodiment is as follows:
the embodiment of the invention provides a grid-connected inverter control method integrated with an active damping function, which can be applied to a grid-connected inverter. Referring to FIG. 1, in the figure, L 1B ,L 2B ,C B The inverter side inductor, the grid side inductor and the filter capacitor of the grid-connected inverter are integrated with the active damper function respectively. V dc Is a DC side voltage, v g For the mains voltage, Z g As the impedance of the grid, i B Is the active damper port current. Grid-connected inverter and method
For grid-connected current reference value, the current i passes through the port of the active damper B The feedback control strategy realizes the grid-connected function, and in order to inhibit resonance introduced by the LCL filter, the embodiment adopts the capacitance current i C Feedback control strategy, K c Is a feedback coefficient of capacitance current, v MA For modulating the voltage, the current loop using a current regulator G iA (s). The active damper function part comprises a wave trap G NA (s), virtual resistance adaptive regulator and harmonic current reference compensation link G cA (s). The topological structure and the control strategy of the inverter A are the same as those of the grid-connected part of the inverter B.
According to fig. 1, it can be known that the active damper and the grid-connected converter have great similarity in terms of both the topology structure diagram and the manner of connecting the grid system. Both are controlled current sources essentially, current tracking control and phase-locked loop technology are adopted, and an inverter in the system outputs corresponding current according to an instruction signal and is merged into a power grid. Because the basic structures of the active damper and the grid-connected converter are the same as the key technology, unified control can be realized, and the purpose of one machine with multiple functions is achieved. In the invention, the direct-current side capacitor of the active damper is replaced by a direct-current voltage source which is the same as that of the grid-connected inverter. The basic idea behind the proposed active damper is to introduce a variable resonant damping resistance into the grid impedance curve by a power converter with a high control bandwidth to suppress the parallel resonance propagation. Therefore, the active damping function is added on the basis of the grid-connected inverter by designing the filter parameters and the controller parameters of the active damper.
The energy exchange between the active damper and the grid-connected converter and the power grid is the theoretical basis for realizing the unified control of the active damper and the grid-connected converter. By adding the self-adaptive active damping into the current control process, the resonance suppression effect under the weak grid can be realized while the grid-connected converter works normally. The unified control system of the active damper and the grid-connected converter comprises resonance suppression and grid-connected inversion functions under a weak power grid. When the system normally works, the system works in a grid-connected inversion and active damper unified control mode. And the voltage and current detection module detects the PCC to obtain the command values of the active and reactive currents and the harmonic wave quantity of the high-order voltage. The control part superposes the instruction value obtained by the active damper and the grid-connected instruction current, carries out current tracking control, outputs corresponding PWM waves, controls the on-off of a switch tube of the converter module, realizes the unified control of the active damper and the grid-connected converter, eliminates the resonance problem in a weak power grid, and improves the power quality of the power grid. Therefore, the electric energy quality of the power grid is improved while clean energy is utilized to the maximum extent, the utilization rate of equipment is improved, the investment is saved, and the economic benefit is improved.
In fig. 1:
wherein, ω is 0 ＝2πf 0 Is the fundamental angular frequency, Q is the quality factor, taken in the present invention as 10,K pA And K rA Respectively are the proportionality coefficient and the resonance coefficient of the regulator; omega iA ＝2πf iA Is to consider the bandwidth of the resonance term required by-3 dB, i.e., the resonance term is in h (omega) 0 ±ω iA ) The gain at (b) is 0.707K rA In order to ensure that the active damper can normally work when the fundamental frequency fluctuates within the range of 49.5Hz to 50.2Hz, f is taken iA =0.5Hz, corresponding to ω iA ＝πrad/s，ω iA For the bandwidth of the resonance term, G dA And(s) is control delay. First, pass through a wave trap G NA (s) filtering fundamental component in PCC voltage to obtain resonance voltage v at PCC pcch . In order to derive the virtual resistance value, the harmonic current absorbed by the active damper from the grid should be referenced as:
wherein i h_ref A reference value of harmonic current which needs to be absorbed from a power grid is set for the active damper; i.e. i 1_ref The reference value of the fundamental current fed back to the power grid by the active damper is used; v. of pcch Is the resonant voltage at PCC; r v The virtual resistance value may be adaptively adjusted according to a resonant component of the PCC voltage. Detecting the phase of the fundamental component of the PCC voltage by a phase-locked loop, and calculating the remaining chord quantity cos theta and
the product of (a) is the fundamental current reference i fed back to the power grid by the active damper 1_ref . Active damper port current i B Is usually the reference of i h_ref And i 1_ref Difference, but to more accurately derive the virtual resistance value, the present invention is implemented at i h_ref And i 1_ref Before subtraction, it is fed into a harmonic current reference compensation unit G cA (s)。G cA (s) output signal and i 1_ref After subtraction, the sum is then i B Is subtracted from the sampled signal, the resulting error signal is fed to a current regulator G iA (s) of the reaction mixture. In order to suppress the resonance peak of LCL filter, a capacitance current feedback active damping method is adopted, K c Is the feedback coefficient of the capacitance current. G iA Subtracting the feedback signal of the capacitor current after the output of(s) is inverted to obtain the modulation voltage v MA Finally, obtaining the switching tube Q through single-pole frequency multiplication SPWM modulation B1 ～Q B6 The drive signal of (2).
Adaptive control is added in the active damper, and the virtual resistance adaptive regulator based on the RBF network is selected in the embodiment, so that the regulator can approach any continuous function with any precision, the learning speed is high, and the problem of local minimum is avoided. The introduction of the virtual resistance self-adaptive regulator does not increase the complexity of a control system, and the parameters of the control system can timely regulate the parameters of the self-adaptive regulator according to the change of external conditions.
As shown in fig. 2, the virtual resistance adaptive regulator includes two parts: virtual resistance (R) v ) A self-correcting controller and an RBF network. In the figure: h = [ H ] 1 ,h 2 ,…,h m ] T Is the radial basis vector, h, of the RBF network m Is the mth radial basis; m is the number of hidden layers; w = [ W = 1 ,w 2 ,…,w m ] T As weight vector of RBF network, w m Is the mth weighting coefficient; b = [ B ] 1 ,b 2 ,…,b m ] T As a base width vector of the RBF network, b m Is the mth base width value; c j ＝[c j1 ,c j2 ,…,c ji ,…,c jn ] T As a central vector of the RBF network node, c jn Is the mth central vector; i =1,2, \8230;, n.
In the control process, R v The self-correcting controller plays a leading role, and the RBF network plays a regulating role. As can be seen from fig. 2, the RBF network has two inputs: r v The output of the self-correcting controller and the PCC resonant voltage, can be expressed as
x＝[x 1 (k) x 2 (k)] T ＝[R v (k-1) v pcch (k-1)] T (5)
In the formula: x is the input matrix, x 1 (k) Is an input quantity 1, namely R v Value of the kth carry-over iteration, x 2 (k) Is the input quantity 2 i.e. v pcch Substituting the value of the iteration for the kth time; r v (k-1) is R output at the k-1 th iteration v Value of v pcch (k-1) is v outputted at the k-1 th iteration pcch A value of (d); k is the number of iterations; when the external environment suddenly changes to generate larger disturbance, the RBF network obtains an ideal tracking value y through the identifier m (k) I.e. the output of the RBF network
y m (k)＝w 1 h 1 +w 2 h 2 +L+w m h m (6)
y m (k) And v pcch (k) There will be an error e (k) between them, expressed as
e(k)＝y m (k)-v pcch (k) (7)
Defining RBF network weight learning error index as
Outputting radial basic value H to RBF network by gradient descent method j (k) The output weight W j (k) Base width vector B j (k) Node vector C j (k) Updating in real time and iteratively calculating new H j (k)、W j (k)、B j (k)、C j (k) And the tracking performance of the RBF network is ensured, and the subscript j is the moment j. To obtain v pcch (k) Sensitivity information input to the RBF network, namely a Jacobian matrix.
And (4) sending the Jacobian matrix obtained by the RBF network to an active damper for correcting and calculating system parameters. Definition error e c Is composed of
then 1/R V The value can be expressed as
In the formula:
is a momentum factor; eta is the learning rate;
is composed of
The difference term of (a); e.g. of the type c (k) As the error at the k-th iteration
Thus, the output of the active damper is
Equation (13) is used only as a dimensionless value, 1/R if the grid-connected inverter system is inherently stable V It will approach 0 indefinitely, where the virtual resistance approaches infinity. And once the system is unstable, 1/R V Will automatically increase and adaptively provide damping for the resonance between the grid-tied inverter and the grid. Then 1/R V Will eventually be adjusted to a threshold value that will cause the system to just remain at
The critical steady state of the gas phase in the gas phase,
is the resonant voltage reference at PCC.
It should be noted that if a fixed R is given directly V Then R V When the value of (2) is too large, the resonance component in the PCC voltage can exceed an acceptable range, and the stability of the system cannot be ensured; and R is V Is too small, although the resonance component in the PCC voltage can be better damped, the port current of the active damper stillBut may increase and thus increase power consumption. The virtual resistance self-adaptive adjusting method based on the RBF network can compromise the stability of the system and the power loss of the active damper to obtain an optimized virtual resistance value.
The embodiment of the invention is simulated in Matlab/Simulink, the parameter setting of the grid-connected inverter can be shown in a table 1, and the parameter setting of the active damper can be shown in a table 2.
TABLE 1
TABLE 2
In order to verify the superiority of the method provided by the invention under the condition of weak power grid, the embodiment of the invention respectively simulates the system under different scenes.
When the grid inductance is 0.2mH, simulation waveforms of the grid-connected inverter output current and the PCC voltage before and after the active damper is incorporated are respectively shown in fig. 3 and 4, and it can be seen that the grid-connected inverter output current and the PCC voltage are seriously distorted before the active damper is incorporated. After the active damper is incorporated, the resonance is effectively damped, and the grid-connected inverter recovers stable operation. According to simulation results, the active damper designed by the invention can effectively inhibit resonance caused by the inductance change of the power grid under a weak power grid.
Fig. 5 shows a current waveform output by the active damper after the resonance is effectively suppressed, where the output current waveform is good, and illustrates that the active damper designed by the present invention can function as a grid-connected inverter to normally operate and simultaneously play a role in suppressing resonance under a weak grid.
Fig. 6 and 7 are waveforms of resonant current output by the active damper when the adaptive virtual resistance method based on the RBF network according to the present invention is adopted and when a fixed resistor (where the selected resistor is 10 Ω) is adopted, respectively.
Example two:
the embodiment of the invention provides a grid-connected inverter integrated with an active damping function, which can be used for realizing the method of the first embodiment, and comprises the following steps:
a wave trap: for filtering out the voltage v of the point of common coupling pcc To obtain a resonance voltage v at the point of common coupling pcch ；
Virtual resistance adaptive regulator: self-adaptive adjustment of virtual resistor R according to stability of grid-connected inverter v And according to the resonance voltage v output by the wave trap pcch Calculating and obtaining a harmonic current reference value i absorbed by the active damper from a power grid h_ref ；
A phase-locked loop: for detecting the voltage v of the point of common coupling pcc To calculate the fundamental current reference value i of the active damper feeding back to the power grid 1_ref ；
And a harmonic current reference compensation step: for reference value i of the harmonic current h_ref Compensation is carried out;
and an error calculation step: the output current of the harmonic current reference compensation link is compared with a fundamental current reference value i 1_ref Subtracting the current I from the collected current I at the port of the active damper B Subtracting to obtain a first error signal;
current regulator: for current regulating the first error signal;
a modulation voltage generation link: is used for subtracting the filter capacitor current feedback signal after inverting the output signal of the current regulator to obtain a modulation voltage v MA (ii) a The filter capacitor is connected between an inverter side inductor and a grid side inductor of the grid-connected inverter;
a PWM modulator: for varying the modulation voltage v MA And generating a driving signal for controlling a switching tube in the grid-connected inverter.
The grid-connected inverter integrating the active damping function, provided by the embodiment of the invention, solves the problems that grid-connected inverter systems and grid impedance are mutually coupled under the condition of weak grid, so that grid-connected current contains a large amount of harmonic waves and even is unstable.
In some embodiments, the trap, the adaptive virtual resistance adjuster, the harmonic current reference compensation element, and the current adjuster may be general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs), single-chip processors, ARM (Acorn RISC machines), or any combinations thereof. The wave trap, the virtual resistance adaptive regulator, the harmonic current reference compensation link, and the current regulator can also be any conventional processor, control device, micro-control device or state machine. The traps, virtual resistance adaptive regulators, harmonic current reference compensation elements, current regulators may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP, and/or any other such configuration.
Example three:
the embodiment of the invention also provides an electronic terminal, which comprises a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method of embodiment one.
Example four:
embodiments of the present invention further provide a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the method of an embodiment.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A grid-connected inverter control method integrating an active damping function is characterized by comprising the following steps:
voltage v of point of common coupling pcc Is sent into a wave trap G NA (s) filtering out the PCC voltage v pcc To obtain a resonant voltage v at the point of common coupling pcch ；
According to the resonance voltage v pcch And adaptively adjusting the obtained virtual resistance R v Calculating to obtain a harmonic current reference value i absorbed by the active damper from the power grid h_ref ；
According to the voltage v of the point of common coupling pcc The fundamental component of the active damper calculates a fundamental current reference value i fed back to the power grid by the active damper 1_ref ；
The fundamental current reference value i 1_ref Fed into harmonic current reference compensation link G cA (s) for the harmonic current reference value i h_ref Performing harmonic current reference compensation;
compensating the harmonic current reference link G cA (s) output current and fundamental current reference value i 1_ref Subtracting the current I from the collected current I at the port of the active damper B Subtracting to obtain a first error signal;
feeding said first error signal into a current regulator G iA (s) passing said current regulator G iA Subtracting the filter capacitor current feedback signal after the output signal of(s) is inverted to obtain the modulation voltage v MA (ii) a The filter capacitor is connected between an inverter side inductor and a grid side inductor of the grid-connected inverter;
applying the modulation voltage v MA And sending the signal to a PWM modulator to generate a driving signal for controlling a switching tube in the grid-connected inverter.
2. The grid-connected inverter control method integrated with active damping function according to claim 1,the virtual resistor R v Realizing self-adaptive adjustment based on the RBF network;
the RBF network uses a virtual resistor R v Output of self-corrector and said resonance voltage v pcch As an input quantity, an ideal tracking value is acquired by the identifier.
3. The control method of the grid-connected inverter with the integrated active damping function according to claim 2, wherein the output radial fundamental value, the output weight, the fundamental width vector and the node vector of the RBF network are updated in real time by a gradient descent method to obtain a characteristic resonant voltage v pcch And (3) sending the Jacobian matrix of the sensitivity information input by the RBF network to an active damper for correcting and calculating system parameters.
4. The method for controlling the grid-connected inverter integrating the active damping function according to claim 3, wherein the output of the active damper is as follows:
in the formula: v. of pcch (k) For the resonant voltage v at the kth iteration pcch A value of (d); r v Is a virtual resistance; e.g. of a cylinder c (k) For the k-th iteration error the error is,
for the resonant voltage v at the kth iteration pcch Reference value of v pcch (k-1) is the resonance voltage v at the k-1 iteration pcch A value of (d); e.g. of a cylinder c And (k-1) is the (k-1) th iteration error.
5. The grid-connected inverter control method integrated with active damping function according to claim 1, wherein the control method is characterized in thatSaid wave trap G NA (s) is expressed as:
in the formula: omega 0 ＝2πf 0 Is the fundamental angular frequency, Q is the quality factor, f 0 Is the grid frequency.
6. The method as claimed in claim 1, wherein the harmonic current reference compensation step G is performed in the step of controlling the grid-connected inverter with integrated active damping function cA (s) is represented by
In the formula: k pA Is the proportionality coefficient of the current regulator; omega iA Is the resonance term bandwidth; g dA (s) controlling the delay; l is a radical of an alcohol 1B An inverter side inductor of the grid-connected inverter; l is a radical of an alcohol 2B Is a net side inductor.
7. The active damping function integrated grid-connected inverter control method according to claim 1, wherein the current regulator G is connected to the grid-connected inverter through a connection line iA (s) is expressed as:
in the formula, K pA And K rA The proportionality coefficient and the resonance coefficient of the current regulator are respectively; omega iA Is the resonance term bandwidth; omega 0 ＝2πf 0 Is the fundamental angular frequency, f 0 Is the grid frequency.
8. The active damping function integrated grid-connected inverter control method according to claim 1, wherein the common coupling point voltage v is obtained according to pcc The fundamental component of the active damper calculates a fundamental current reference value i fed back to the power grid by the active damper 1_ref The method comprises the following steps:
detecting the pcc voltage v using a phase-locked loop pcc The phase of the fundamental component of (a);
the voltage v of the common coupling point pcc The cosine quantity of the phase of the fundamental component of (a) and the grid-connected current reference value
Multiplying, namely the product is the fundamental current reference value i 1_ref 。
9. The control method of the grid-connected inverter integrating the active damping function according to claim 1, wherein the filter capacitor current feedback signal is obtained by calculating after multiplying the collected filter capacitor current by a filter capacitor current feedback coefficient.
10. A grid-connected inverter integrating an active damping function is characterized by comprising:
a wave trap: for filtering out the voltage v of the point of common coupling pcc To obtain a resonance voltage v at the point of common coupling pcch ；
The virtual resistance self-adaptive regulator: self-adaptive adjustment of virtual resistance R according to stability of grid-connected inverter v And according to the resonance voltage v output by the wave trap pcch Calculating and obtaining a harmonic current reference value i absorbed by the active damper from a power grid h_ref ；
A phase-locked loop: for detecting the voltage v of the point of common coupling pcc To calculate the fundamental current reference value i of the active damper feeding back to the power grid 1_ref ；
And a harmonic current reference compensation step: for reference value i of the harmonic current h_ref Performing compensation;
and an error calculation step: the output current of the harmonic current reference compensation link is compared with a fundamental current reference value i 1_ref The difference is taken from the first and the second,then the current i is compared with the collected current i of the port of the active damper B Subtracting to obtain a first error signal;
current regulator: for current regulating the first error signal;
a modulation voltage generation link: is used for subtracting the filter capacitor current feedback signal after inverting the output signal of the current regulator to obtain a modulation voltage v MA (ii) a The filter capacitor is connected between an inverter side inductor and a grid side inductor of the grid-connected inverter;
a PWM modulator: for varying the modulation voltage v MA And generating a driving signal for controlling a switching tube in the grid-connected inverter.
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