CN115425864B

CN115425864B - Inverter virtual resistance compensation method, device and equipment integrated with active damper

Info

Publication number: CN115425864B
Application number: CN202211148460.XA
Authority: CN
Inventors: 姜云龙; 史明明; 司鑫尧; 张宸宇; 杨景刚; 袁晓冬; 葛雪峰; 刘瑞煌; 缪惠宇; 肖小龙; 苏伟
Original assignee: Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Current assignee: Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Priority date: 2022-09-21
Filing date: 2022-09-21
Publication date: 2023-06-30
Anticipated expiration: 2042-09-21
Also published as: CN115425864A

Abstract

The invention relates to the field of power electronics, in particular to an inverter virtual resistance compensation method, device and equipment for an integrated active damper, which comprises the following steps: a grid-connected inverter integrating the function of an active damper is connected in parallel at the PCC, and the active damper is a capacitor current feedback strategy; when the power grid is normal, the grid-connected inverter and the power grid are normally connected, and the active damper generates capacitance current and grid-connected current of the grid-connected inverter to be injected into the PCC together; when the grid is weak, the grid-connected inverter obtains grid resonance parameters, virtual resistors are generated inside, virtual resistor resonance currents are generated through the grid resonance parameters and the virtual resistors, the virtual resistor resonance currents, the grid-connected currents and the capacitor currents are injected into the PCC together, and PCC resonance is restrained. According to the invention, the function of integrally inhibiting the resonance of the PCC by upgrading and reforming each inverter connected to the PCC is avoided, the universality is improved, and the cost is greatly reduced.

Description

Inverter virtual resistance compensation method, device and equipment integrated with active damper

Technical Field

The present invention relates to the field of power electronics, and in particular, to a method, an apparatus, and a device for compensating for virtual resistance of an inverter integrated with an active damper.

Background

In recent years, renewable energy power generation technology has been attracting attention, and a grid-connected inverter is used as an interface between a renewable energy power generation unit and a public power grid, and has a main function of injecting stable and high-quality current into the power grid. In some cases, the transmission line between the inverter and the power grid is long, the impedance of the power grid is not negligible, and the system presents weak power grid characteristics. The characteristics are as follows: the power grid has non-negligible impedance, the impedance value can fluctuate, and the PCC (Point of Common Coupling ) voltage is distorted due to the existence of the power grid impedance, so that the control performance of the grid-connected inverter is seriously affected, and even an unstable phenomenon occurs.

In the prior art, a power electronic converter is additionally arranged on a parallel connection part of a grid-connected inverter and PCC to simulate the resistance characteristic as a damping device, and the converter is also called an active damper which can solve the problem of LCL stability of a single inverter.

Under weak current network, the grid-connected inverter has stability problem of harmonic resonance in a wide frequency band, such as distortion of grid-connected current, oscillation of grid-connected power, and even the whole inverter can not stably operate when serious, and the whole inverter is cut off from a power grid by a protection device. Even if the inverter itself is stable, severe resonance between the grid-connected inverter and the grid may still occur when the grid impedance is disturbed. When a plurality of inverters exist in the grid-connected system, the optimization scheme of the control strategy of the grid-connected inverter needs to upgrade, reform or replace each inverter in the grid-connected inverter system, so that the cost is overlarge and the universality is poor.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

The invention provides an inverter virtual resistance compensation method, device and equipment integrating an active damper, and accordingly the problems in the background technology are effectively solved.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: an inverter virtual resistance compensation method integrated with an active damper comprises the following steps:

a grid-connected inverter integrating the function of an active damper is connected in parallel at the PCC, and the active damper is a capacitor current feedback strategy;

when the power grid is normal, the grid-connected inverter and the power grid are normally connected, and the active damper generates capacitance current and grid-connected current of the grid-connected inverter to be injected into PCC together;

and when the grid is in a weak current network, the grid-connected inverter acquires a grid resonance parameter, generates a virtual resistor internally, generates a virtual resistor resonance current through the grid resonance parameter and the virtual resistor, and jointly injects the virtual resistor resonance current, the grid-connected current and the capacitance current into the PCC to inhibit PCC resonance.

Further, when the power grid resonance parameters are obtained, firstly obtaining the voltage at the PCC;

and filtering fundamental waves and low-order harmonic waves in the voltage through a wave trap to obtain resonant voltage.

Further, the resistance value of the virtual resistor is adaptively adjusted according to the resonance voltage.

Further, the adaptive adjustment of the virtual resistance value includes:

firstly, squaring the resonance voltage;

filtering the pulsating component by a first-order low-pass filter to obtain a square average value;

comparing the square average value with a preset threshold value and sending the square average value and the preset threshold value to a PI regulator;

and obtaining the reciprocal of the virtual resistance value through the limiting link.

Further, after the virtual resistor resonance current is generated, compensation gain is performed on the virtual resistor resonance current, so that the impedance of the virtual resistor is still pure resistance characteristic in a target damping frequency band when the switching frequency of the inverter is low.

Further, when compensating gain is performed on the virtual resistance resonance current, the virtual resistance resonance current is multiplied by

Said->

The method comprises the following steps:

wherein, the liquid crystal display device comprises a liquid crystal display device,

for discretized transfer function, +.>

And->

An inversion side inductor and a network side inductor of the grid-connected inverter respectively, < >>

Is a proportional coefficient->

Is the sampling period.

Further, the said

Transfer function of non-ideal GI->

Transfer function discretized by FOH, < >>

The method comprises the following steps:

；

for cut-off angular frequency +.>

Is the angular frequency at the point of maximum gain.

The invention also comprises an inverter virtual resistance compensation method device integrated with the active damper, which comprises a grid-connected inverter, wherein the grid-connected inverter is connected in parallel with the PCC, the active damper is integrated with the grid-connected inverter, the active damper is a capacitor current feedback strategy, and the PCC harmonic suppression method is used when the grid-connected inverter operates.

The invention also includes a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the method as described above when executing the computer program.

The invention also includes a storage medium having stored thereon a computer program which, when executed by a processor, implements a method as described above.

The beneficial effects of the invention are as follows: according to the invention, the grid-connected inverter integrating the function of the active damper is connected in parallel at the PCC, the active damper is a capacitor current feedback strategy, the grid-connected inverter is connected with the PCC as a common grid-connected inverter when a power grid is normal, the grid-connected inverter is connected with the PCC as active damping integrally when a weak power grid is used, a virtual resistor is generated, and a virtual resistor resonance current is generated, so that virtual resistor impedance is realized on the grid-connected inverter, resonance of the PCC is suppressed, the function of integrally suppressing resonance of the PCC by upgrading and reforming each inverter connected with the PCC is avoided, the universality is improved, and the cost is greatly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.

FIG. 1 is a flow chart of the method of example 1;

FIG. 2 is a topology diagram of an LCL grid-connected inverter system with an integrated active damper connected in parallel at the PCC in embodiment 2;

fig. 3 is a control block diagram of an inverter a in embodiment 2;

FIG. 4 is a control block diagram of a grid-connected inverter with an additional active damper function in embodiment 2;

FIG. 5 is a representative port equivalent circuit diagram of FIG. 2;

FIG. 6 is a current open loop bode plot;

FIG. 7 is a non-ideal GI Bode diagram;

FIG. 8 is a diagram of virtual resistance-to-Bode diagram after considering the delay element;

fig. 9 is a waveform diagram of an experiment of grid-connected current and PCC voltage of the inverter a under a weak grid;

fig. 10 is a waveform diagram of an experiment of grid-connected current and PCC voltage of an inverter B using the compensation method of the present disclosure under a weak grid;

fig. 11 is a schematic structural diagram of a computer device.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.

Example 1:

as shown in fig. 1: an inverter virtual resistance compensation method integrated with an active damper comprises the following steps:

when the power grid is normal, the grid-connected inverter and the power grid are normally connected, and the active damper generates capacitance current and grid-connected current of the grid-connected inverter to be injected into the PCC together;

when the grid is weak, the grid-connected inverter obtains grid resonance parameters, virtual resistors are generated inside, virtual resistor resonance currents are generated through the grid resonance parameters and the virtual resistors, the virtual resistor resonance currents, the grid-connected currents and the capacitor currents are injected into the PCC together, and PCC resonance is restrained.

The grid-connected inverter integrating the function of the active damper is connected in parallel at the PCC, the active damper is a capacitor current feedback strategy, the grid-connected inverter is connected with the PCC as a common grid-connected inverter when a power grid is normal, the grid-connected inverter is integrally connected with the PCC as active damping when a weak power grid is used, a virtual resistor is generated, and virtual resistor resonance current is generated, so that virtual resistor impedance is realized on the grid-connected inverter, resonance of the PCC is restrained, the function of integrally restraining the resonance of the PCC by upgrading and reforming each inverter connected with the PCC is avoided, the universality is improved, and the cost is greatly reduced.

In this embodiment, when the grid resonance parameter is obtained, the voltage at the PCC is obtained first;

As the preference of the embodiment, the resistance value of the virtual resistor is adaptively adjusted according to the resonance voltage, and the adaptively adjusted virtual resistor has a good dynamic range and can effectively reduce power consumption.

Wherein, virtual resistance value self-adaptation adjustment includes:

firstly, squaring the resonance voltage;

As a preferable example of the above embodiment, after the virtual resistor resonance current is generated, it is first compensated for gain so that the impedance of the virtual resistor is still a pure resistance characteristic in the target damping frequency band when the switching frequency of the inverter is low.

Multiplying the virtual resistance resonance current by the compensation gain of the virtual resistance resonance current

，

The method comprises the following steps:

discretized transfer function for non-ideal GI (Generalized Integrator ), +.>

And->

Is a proportional coefficient->

Is the sampling period.

Transfer function of non-ideal GI->

Discretized transfer function by FOH (First-Order Hold), first-Order Hold)>

The method comprises the following steps:

；

for cut-off angular frequency +.>

Is the angular frequency at the point of maximum gain.

Because the differential term is difficult to realize in practical application and sensitive to noise, the integral transfer function can be used for equivalently replacing the differential term, the non-ideal GI can well replace the differential term, the influence of noise can be effectively reduced, and the method is characterized in that

To adjust->

The gain at the position can effectively reduce the influence of noise. In order to keep the differential properties of the non-ideal GI within the Nyquist frequency>

Should be equal to->

，/>

Is the sampling frequency.

After the virtual resistor resonance current is compensated, the problem of phase deviation can be well solved, the virtual resistor impedance is always kept near 0 DEG at the phase of the target resonance frequency band, the 100Hz to 2kHz target damping frequency band can completely show the resistance characteristic to the outside, the accuracy of the virtual resistor is greatly improved, and the inverter has good resonance damping effect when the inverter works in a grid-connected mode. The contradiction between the switching frequency and the virtual resistor control precision can be effectively solved, and the accuracy of the grid-connected system is enhanced.

The embodiment also comprises an inverter virtual resistance compensation device integrated with the active damper, wherein the inverter virtual resistance compensation device comprises a grid-connected inverter, the grid-connected inverter is connected in parallel at the PCC, the grid-connected inverter is integrated with the active damper, the active damper is a capacitor current feedback strategy, and the PCC harmonic suppression method is used when the grid-connected inverter operates.

Example 2:

as shown in fig. 2, a three-phase LCL-type inverter a with an active damping function is connected in parallel to the PCC, the inverter B is a conventional LCL-type grid-connected inverter, and the circuit topologies of the two grid-connected inverters are identical, wherein

The inductor, the network side inductor and the filter capacitor are respectively the inversion side inductor, the network side inductor and the filter capacitor of the inverter B>

The power supply is respectively an inversion side inductor, a network side inductor and a filter capacitor of the inverter A. />

For DC side voltage, ">

For mains voltage>

Grid impedance->

And->

The port currents of inverter a and inverter B, respectively.

The mathematical model and control strategy of the inverter a integrated with the active damping function will be given below, and the rest of the conventional inverter B is identical to the inverter a except for the grid-connected function.

Fig. 3 is a control block diagram of an inverter a integrated with an active damping function, whose control objective is mainly to realize the active damping function while realizing the grid-connected function, in which

For the reference value of the grid-connected current, the grid-connected current is used for +.>

The feedback control strategy realizes the grid-connected function, and in order to effectively inhibit resonance introduced by the LCL filter, the invention adopts capacitive current +.>

Feedback active damping strategy, < >>

Is a capacitive current feedback coefficient. />

For modulating the voltage, the current loop adopts a PR controller, and the transfer function is that

Wherein the method comprises the steps of

，/>

Proportional and integral coefficients, respectively +.>

For fundamental angular frequency, ++>

Taking the bandwidth of the resonance term required by-3 dB into consideration, in order to ensure that the inverter can work normally when the fundamental wave frequency fluctuates within the range of 49.5Hz to 50.2Hz

rad/s。

Unlike the control method of the traditional inverter, the development target of the inverter A with the active damping function mainly realizes the active damping function while realizing the grid-connected function. The inverter A is added with an active damping function on the basis of grid-connected operation, and virtual damping is constructed by a PCC voltage feedforward method to restrain resonance. As shown in fig. 3, through a wave trap

Filtering fundamental wave and low harmonic wave in PCC voltage to obtain resonance voltage +.>

And the set virtual resistance value +.>

Dividing to obtain virtual resistance resonance current instruction +.>

Wherein the virtual resistance value +.>

An adaptive adjustment method is adopted.

Wherein the method comprises the steps of

Is the harmonic frequency>

Is the figure of merit.

Virtual resistance value

The virtual resistance value of the active damper is adaptively adjusted according to the resonant component of PCC voltage, and the target resonant component is +.>

Squaring by a first order low pass filter +.>

Filtering the pulsation component to obtain square average value +.>

The square mean value and a preset threshold value +.>

Comparison is fed into PI regulator->

Obtaining the reciprocal of the virtual resistance value through a limiting link>

For calculating a harmonic current reference of the active damper. Wherein:

the turning frequency is generally the fundamental frequency, < ->

、/>

The proportional and integral coefficients of the regulator, respectively. The self-adaptive regulated resistor has better dynamic performance and can effectively reduce power loss.

From fig. 2 and 3, a control block diagram of an inverter a is obtained, in which H _iCA Is a capacitive current feedback coefficient, as shown in fig. 4.

1.5 beat delay introduced for digital control,/->

For the sampling period of inverter a, +.>

Is the sampling frequency.

The loop gain of the current loop of the inverter A can be obtained as follows:

according to fig. 4, an inverter a-port current expression can be written as:

is an equivalent fundamental current source->

For the original port impedance of inverter a, +.>

The expressions of the impedance corresponding to the virtual resistance are respectively

（9）

（10）

（11）

An equivalent circuit diagram of the inverter a with the active damping function can be drawn according to the equations (8) to (11), as shown in fig. 5.

In step 3: the resonant frequency between the grid-tied inverter and the grid is typically 1kHz-2kHz. As can be seen from the analysis in step 2, according to equation (11),

is>

Related to the following. In the addition of compensation link->

Before approximately ignoring the trap +.>

To make->

Is required to be->

This is usually only well below the cut-off frequency of the current loop +.>

Is established. At->

Frequency bands near and above due to +.>

Is no longer established, will cause->

No longer exhibits a resistive characteristic, resulting in an inferior damping effect on resonance. As shown in fig. 6, the loop gain of the inverter current loop using the conventional control method +.>

Decreasing with increasing frequency, the loop gain within the target resonant frequency band 1kHz-2kHz has approximated and traversed even 0dB. It can be seen that the tracking performance of the harmonic current in the target frequency band is poor, and the output impedance at the moment has phase deviation and no longer shows pure resistance characteristics. Stability problems under weak grids may even be exacerbated because the equivalent output impedance may exhibit inductive characteristics.

Because the control precision and accuracy of the virtual resistor are greatly reduced due to the lack of the high-frequency-band current loop gain, the virtual resistor cannot play a good harmonic damping role in the target frequency band at the moment, the stability of a system is even reduced, the problem severity is often aggravated due to the limitation of the switching frequency, and the grid-connected function of active damping is also limited. In order to solve the technical problem, a brand-new virtual resistor compensation control is provided, the compensated virtual resistor shows good resistance characteristics in a high frequency band under the condition that the switching frequency of the inverter is not high, and the problems that the resistance characteristics of the virtual impedance are poor and the resonance damping effect is poor due to low switching frequency are solved.

After the inverter is added with the active damping function, the port current

The standard of (2) is usually +.>

And->

In order to more accurately virtualize the resistance, in +.>

And->

Before adding, it is fed into a harmonic current compensation link +.>

. The compensation element of the design has the advantage that the correction can be made independently +.>

Without affecting +.>

And->

Is a characteristic of (a).

The control objective of adding the compensation link is to make the compensation link in the target damping frequency band

Is maintained as pure resistance characteristic, i.e

. Bringing it into (11)

(12)

When the switching frequency is reduced, controlIgnoring bandwidth limited systems

The control effect is not ideal, the influence of 1.5 beat delay on a control loop is considered by adopting digital control, and the delay link is +.>

Can be approximated as +.>

，/>

For the sampling period, an approximated compensation link expression is obtained:

(13)

can verify by adopting the same approximation principle

And the resistance characteristics thereof can be completely restored in the high frequency band.

Since the differential term is difficult to realize in practical application and sensitive to noise, the differential term can be equivalently replaced by an integral transfer function.

The transfer function of the non-ideal GI is shown in equation (14):

（14）

for cut-off angular frequency +.>

For the angular frequency at the maximum gain point, a bode plot of the non-ideal GI is plotted according to equation (14), as shown in fig. 7.

As can be seen from FIG. 7

When in use, the non-ideal GI can well replace the differential term by setting +.>

To adjust->

Should be equal to->

，/>

Is the sampling frequency.

The discrete domain expression of the compensation function after the differential equivalent substitution principle is adopted is as follows:

（15）

wherein the method comprises the steps of

Is->

Transfer function after FOH discretization.

Can be drawn out

The bird's nest graph of (c) is shown in fig. 8.

As can be seen from fig. 8, the loop gain of the current loop decreases with increasing frequency before adding the compensation loop, such that

The phase of (2) is +.>

The frequency band in the vicinity is deviated from 0 degrees by a large margin, the deviation appears from the phase beginning of the 200Hz frequency band, the resistance characteristic is not presented, the situation is more obvious along with the increase of the frequency, the phase deviation is about 40 degrees when the target damping frequency band is 1000Hz, the phase deviation is about 90 degrees when the target damping frequency band is 2000Hz, the inductance characteristic is presented to the outside, the damping can not be provided for the system, and the stability problem under a weak current network can be aggravated.

The virtual resistance compensation method provided by the invention can well solve the problem of phase shift,

the target damping frequency band from 100Hz to 2kHz can completely show resistance characteristics to the outside when the phase of the target resonance frequency band is always kept near 0 degrees. Compared with the compensation method without the compensation function and before improvement, the compensation strategy has the advantages that the effect is obviously improved, the accuracy of the virtual resistor is greatly improved, and the inverter has good resonance damping effect while the inverter is in grid-connected operation.

In summary, the compensation method for the accuracy of the virtual resistor provided by the invention can effectively solve the contradiction between the switching frequency and the control accuracy of the virtual resistor, enhance the stability of a grid-connected system, and enable the grid-connected inverter to integrate the active damping function simultaneously on the premise of grid-connected operation.

Finally, experiments are carried out in an RT-LAB hardware platform, the parameters of the inverter A integrating the active damper function are set as shown in a table 1, and the parameters of the inverter B are set as shown in a table 2. In order to verify the superiority of the method provided by the invention under the condition of weak current network, experiments are carried out on the system under different scenes respectively.

TABLE 1

TABLE 2

FIG. 9,10 gives the case of weak current network

And the current of the inverter B under weak current network and the inverter A integrating the active damper function and the phase voltage waveform of the PCC point a are obtained. As can be seen from fig. 9, under the weak grid condition, the voltage at the PCC of the grid impedance of the originally stable system is distorted to a certain extent, FFT analysis is performed on points a, B and e, when the active damper function is not started by the inverter a integrated with the active damper function, the output current THD values of the inverter B, the grid-connected point and the inverter a with the active damper function are respectively 10.62%, 27.17% and 9.14%, and the harmonic wave is concentrated around 1kHz, so that the system stability is insufficient.

After compensation is carried out on the virtual resistor by adopting the compensation strategy, as shown in fig. 10, the current waveforms of the two inverters and the voltage of the parallel point are obviously improved, FFT analysis is carried out on points c, d and f, when the inverter A with the active damper function starts the active damper function, the THD values of the output current of the inverter B, the parallel point and the inverter A with the active damper function are respectively 3.19%, 3.38% and 3.20%, and the harmonic current content of the target damping frequency band is obviously reduced, so that the virtual resistor compensation strategy has good damping effect on the target resonance frequency band, and the stability of the system is improved. The validity of the method is verified through front-back comparison.

Please refer to fig. 11, which illustrates a schematic structural diagram of a computer device provided in an embodiment of the present application. The embodiment of the present application provides a computer device 400, including: a processor 410 and a memory 420, the memory 420 storing a computer program executable by the processor 410, which when executed by the processor 410 performs the method as described above.

The present embodiment also provides a storage medium 430, on which storage medium 430 a computer program is stored which, when executed by the processor 410, performs a method as above.

The storage medium 430 may be implemented by any type or combination of volatile or nonvolatile Memory devices, such as static random access Memory (Static Random Access Memory, SRAM), electrically erasable Programmable Read-Only Memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), erasable Programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), programmable Read-Only Memory (PROM), read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic disk, or optical disk.

In the description of the present invention, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. The meaning of "a plurality of" is two or more, unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily for the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.

It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.

Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.

The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. The virtual resistance compensation method of the inverter integrated with the active damper is characterized by comprising the following steps of:

the method comprises the steps that a grid-connected inverter integrated with an active damper is connected in parallel at a PCC (power control system), wherein the active damper is a capacitor current feedback strategy;

when a weak current network is used, the grid-connected inverter acquires a power grid resonance parameter, generates a virtual resistor internally, generates a virtual resistor resonance current through the power grid resonance parameter and the virtual resistor, and jointly injects the virtual resistor resonance current, the grid-connected current and the capacitance current into PCC to inhibit PCC resonance;

after the virtual resistor resonance current is generated, compensating gain is firstly carried out on the virtual resistor resonance current, so that the impedance of the virtual resistor is still of pure resistance characteristic in a target damping frequency band when the switching frequency of the inverter is low;

when the power grid resonance parameters are acquired, firstly acquiring voltage at the PCC;

filtering fundamental waves and low-order harmonic waves in the voltage through a wave trap to obtain resonant voltage;

the resistance value of the virtual resistor is adaptively adjusted according to the resonance voltage;

the self-adaptive adjustment of the virtual resistance value comprises the following steps:

firstly, squaring the resonance voltage;

obtaining the reciprocal of the virtual resistance value through a limiting link;

multiplying the virtual resistance resonance current by a compensation gain of the virtual resistance resonance current

Said->

The method comprises the following steps:

；

is a transfer function discretized by non-ideal GI, < >>

And->

Is a proportional coefficient->

Is the sampling period;

the said

Transfer function of non-ideal GI->

Transfer function discretized by FOH, < >>

The method comprises the following steps:

；

for cut-off angular frequency +.>

Is the angular frequency at the point of maximum gain.

2. An inverter virtual resistance compensation device integrated with an active damper, which is characterized by comprising a grid-connected inverter, wherein the grid-connected inverter is connected in parallel at a PCC, the grid-connected inverter is integrated with the active damper, the active damper is a capacitive current feedback strategy, and the grid-connected inverter is operated by using the inverter virtual resistance compensation method integrated with the active damper according to claim 1.

3. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of claim 1 when executing the computer program.