Harmonic immune control method and system for droop control type distributed power supply

Abstract

The invention relates to a droop control type distributed power supply harmonic immune control method, which comprises the following steps of: acquiring a grid-connected point voltage, separating a characteristic sub-harmonic voltage component from the grid-connected point voltage by adopting a harmonic frequency division technology, and generating a harmonic voltage compensation control instruction; active power and reactive power output by the grid-connected inverter are detected, and a fundamental wave voltage control instruction is generated; and synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, and performing voltage and current double-closed-loop control on the composite voltage control instruction to obtain a duty ratio signal of the grid-connected inverter. A traditional droop control type distributed power supply is controlled and improved, and the problem that the output current of the traditional droop control type distributed power supply is seriously distorted when the grid-connected point has the characteristic secondary background harmonic voltage can be effectively solved, so that the quality of the output current of the distributed power supply is improved, and the power generation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of distributed power supply control, and in particular to a droop control type distributed power supply harmonic immunity control method and system. Background Art

[0002] With the gradual penetration of distributed power sources such as rooftop photovoltaics, small photovoltaic power stations, and energy storage in the distribution network, they have become an important carrier for the distribution network to absorb new energy, and their power generation efficiency has also been increasingly valued. As a key interface device between distributed power sources and the power grid, the control strategy of the inverter has a vital impact on improving power generation efficiency. The droop control strategy can meet the seamless switching and operation requirements of distributed power sources in off-grid and grid-connected states, and has therefore been widely used.

[0003] The traditional droop control strategy adjusts the output voltage and frequency of the inverter to achieve stable output of distributed power in different operating states. This control strategy ensures that the distributed power can maintain a stable operating state in both off-grid and grid-connected states, and achieves seamless switching between the two modes.

[0004] However, under the traditional droop control strategy, the inverter exhibits low impedance characteristics in the frequency band above the base frequency, which makes the droop-controlled distributed power supply extremely sensitive to the harmonic voltage at the grid connection point. When a large number of nonlinear loads are connected to the distribution network, the harmonic voltages generated by these loads will cause serious distortion of the output current of the distributed power supply, thereby squeezing out its active power generation capacity at the base frequency and reducing its power generation efficiency. This problem limits the application of the droop control strategy in distribution networks with harsh harmonic environments. Summary of the invention

[0005] In view of this, it is necessary to provide a droop control type distributed power supply harmonic immunity control method and system to solve the above-mentioned defects of the prior art.

[0006] In order to solve the above problems, in a first aspect, an embodiment of the present invention provides a droop control type distributed power source harmonic immunity control method, comprising:

[0007] S1, collects the grid connection point voltage, uses harmonic frequency division technology to separate the characteristic subharmonic voltage components from the grid connection point voltage, and generates harmonic voltage compensation control instructions;

[0008] S2, detects the active power and reactive power output by the grid-connected inverter and generates fundamental voltage control instructions;

[0009] S3, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, performing voltage and current dual closed-loop control on the composite voltage control instruction, and obtaining a duty cycle signal of the grid-connected inverter.

[0010] Preferably, in step S1, generating a harmonic voltage compensation control instruction includes:

[0011] The harmonic voltage compensation control instruction is calculated based on the characteristic subharmonic voltage components separated by the harmonic frequency division technology and the preset harmonic control gain.

[0012] Preferably, the frequency domain principle expression implemented by the harmonic frequency division technology is:

[0013]

[0014] Where HF(s) is the transfer function of the harmonic divider, ω cf is the bandwidth of the harmonic divider, h is the extracted harmonic frequency, ω0 is the fundamental angular frequency, and s is a complex variable.

[0015] Preferably, the calculation formula of the harmonic voltage compensation control instruction is:

[0016] V hf (s) = V PCC (s)·HF(s)·Q

[0017] Where V hf (s) is the harmonic voltage compensation control instruction, V PCC (s) is the voltage signal at the grid-connected point of the distributed generation, and Q is the harmonic control gain.

[0018] Preferably, step S3 specifically includes:

[0019] S31, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction;

[0020] S32, collecting the three-phase voltage output by the grid-connected inverter, and converting it into a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase voltage with the composite voltage control instruction to obtain voltage error information, inputting the voltage error information into the voltage regulator, and the voltage regulator generates a current reference signal according to the voltage error information;

[0021] S33, collecting the three-phase current output by the grid-connected inverter, and converting it to a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase current with the current reference signal output by the voltage regulator, and obtaining a current error signal.

[0022] S34, inputting the current error signal into a current regulator, and the current regulator generates a modulation signal of a grid-connected inverter according to the current error signal.

[0023] S35, inputting the modulation signal output by the current regulator into the modulation circuit, and the modulation circuit generates a duty cycle signal for controlling the inverter switch tube according to the modulation signal.

[0024] Preferably, in step S32, the frequency domain expression of the voltage regulator is as follows:

[0025]

[0026] In the formula, G V (s) represents the transfer function of the voltage regulator, K VP is the proportionality factor of the voltage regulator, K VI is the resonance coefficient of the resonant controller in the voltage regulator, ω c is the bandwidth of the resonant controller in the voltage regulator, ω0 is the fundamental angular frequency, k is the frequency of each resonant control in the resonant controller, and s is a complex variable.

[0027] In a second aspect, an embodiment of the present invention provides a droop control type distributed power supply harmonic immune control system, comprising:

[0028] The harmonic immunity control module is used to collect the grid-connected point voltage, separate the characteristic subharmonic voltage components from the grid-connected point voltage using the harmonic frequency division technology, and generate harmonic voltage compensation control instructions;

[0029] A fundamental wave droop control module is used to detect the active power and reactive power output by the grid-connected inverter and generate fundamental wave voltage control instructions;

[0030] The voltage-current dual closed-loop control module is used to synthesize the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, perform voltage-current dual closed-loop control on the composite voltage control instruction, and obtain a duty cycle signal of the grid-connected inverter.

[0031] In a third aspect, the present invention further provides an electronic device, including a memory and a processor, wherein:

[0032] The memory is used to store programs;

[0033] The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the droop control type distributed power supply harmonic immunity control method as described in the embodiment of the first aspect of the present invention.

[0034] In a fourth aspect, the present invention further provides a computer-readable storage medium for storing computer-readable programs or instructions, which, when executed by a processor, can implement the steps in the droop-controlled distributed power supply harmonic immunity control method as described in the embodiment of the first aspect of the present invention.

[0035] Compared with the prior art, the droop control type distributed power source harmonic immunity control method provided by the present invention has the following beneficial effects:

[0036] 1) Compared with the existing full-frequency domain control, the present invention uses the harmonic frequency division extraction method to separate and extract only the characteristic subharmonics of the grid connection point. This method can effectively utilize the inverter control bandwidth, reduce the requirements for switching frequency, and thus reduce switching losses and extend the life of the equipment.

[0037] 2) Compared with the existing harmonic current feedback control method, the present invention adopts the harmonic voltage feedforward control method, which will not affect the stability of the system. At the same time, the fundamental wave and the harmonic domain are independently controlled, and there is no coupling interference between them, which further improves the overall control performance and system stability.

[0038] 3) When there is a characteristic sub-harmonic voltage at the grid connection point of the traditional droop control type distributed power supply, the output current will be seriously distorted. The present invention effectively overcomes this problem by introducing the harmonic immunity control method and significantly improves the output current quality of the distributed power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of the droop control type distributed power source harmonic immunity control method provided by the present invention;

[0040] Figure 2 A control schematic diagram of a three-phase grid-connected inverter for a distributed power source provided by the present invention;

[0041] Figure 3 The current waveform diagram of the distributed power supply output after adopting the harmonic immunity control method of the present invention;

[0042] Figure 4 is the total harmonic distortion of the current output by the distributed power supply after the harmonic immunity control method of the present invention is adopted;

[0043] Figure 5 A structural block diagram of the droop control type distributed power supply harmonic immune control system provided by the present invention;

[0044] Figure 6 This is a structural block diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0046] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0047] At present, the traditional droop control strategy adjusts the output voltage and frequency of the inverter to achieve stable output of distributed power sources under different operating conditions. This control strategy ensures that the distributed power source can maintain a stable operating state both in off-grid and grid-connected states, and achieves seamless switching between the two modes. However, under the traditional droop control strategy, the inverter exhibits a low impedance characteristic in the frequency band above the base frequency, which makes the droop-controlled distributed power source extremely sensitive to the harmonic voltage at the grid connection point. When a large number of nonlinear loads are connected to the distribution network, the harmonic voltages generated by these loads will cause serious distortion of the output current of the distributed power source, thereby affecting its active power generation capacity at the base frequency.

[0048] In view of this, the present invention provides a droop-controlled distributed power source harmonic immunity control method, which improves the control of the traditional droop-controlled distributed power source and can effectively overcome the problem of severe output current distortion of the traditional droop-controlled distributed power source when there is a characteristic sub-background harmonic voltage at the grid connection point, thereby improving the output current quality of the distributed power source and improving the power generation efficiency. The following will be described and introduced through multiple embodiments.

[0049] Figure 1 The flowchart of the droop control type distributed power source harmonic immunity control method provided by the present invention is as follows. Figure 1 As shown, the droop control type distributed power source harmonic immunity control method includes steps S1 to S3, wherein:

[0050] Step S1, collecting the grid connection point voltage, using the harmonic frequency division technology to separate the characteristic subharmonic voltage components from the grid connection point voltage, and generating the harmonic voltage compensation control instruction.

[0051] Figure 2 The control principle of the three-phase grid-connected inverter of distributed power supply is shown in Figure 2 ,The three-phase grid-connected inverter (referred to as grid-connected inverter in this article) is used to convert the direct current generated by distributed power sources (such as solar panels, wind turbines, etc.) into alternating current with the same frequency and phase as the grid voltage, and feed it into the grid.

[0052] In step S1, first, the grid connection point voltage is collected, and the grid connection point voltage refers to the voltage at the connection point between the distributed power source and the power grid. In the power system, the distributed power source needs to be connected to the power grid through the grid connection point to realize the transmission and exchange of electric energy.

[0053] Then, the characteristic subharmonic voltage components are separated from the grid connection point voltage by harmonic frequency division technology. In this embodiment, the principle of the harmonic frequency divider is based on multiple parallel bandpass filters, which allow signals within a specific frequency range (i.e., characteristic subharmonics) to pass through while attenuating signals of other frequencies. Through the processing of the harmonic frequency divider, the characteristic subharmonic components that have a greater impact on the output current quality of the distributed power supply can be extracted from the complex grid connection point voltage signal, providing key input for subsequent harmonic compensation control.

[0054] Finally, the harmonic voltage compensation control instruction is calculated based on the characteristic subharmonic voltage components separated by the harmonic frequency division technology and the preset harmonic control gain.

[0055] Among them, the principle expression of the harmonic divider in the frequency domain is:

[0056]

[0057] Where HF(s) is the transfer function of the harmonic divider, ω cf is the bandwidth of the harmonic divider, h is the extracted harmonic frequency, ω0 is the fundamental angular frequency, and s is a complex variable.

[0058] The calculation formula of harmonic voltage compensation control instruction is:

[0059] V hf (s) = V PCC (s)·HF(s)·Q

[0060] Where V hf (s) is the harmonic voltage compensation control instruction, V PCC (s) is the voltage signal at the grid-connected point of the distributed generation, and Q is the harmonic control gain.

[0061] In the embodiment of the present invention, only the characteristic subharmonics of the grid connection point are separated and extracted through the harmonic frequency division extraction method, so that the inverter control bandwidth can be effectively utilized, the requirement for the switching frequency is reduced, and the switching loss is further reduced.

[0062] Step S2, detecting the active power and reactive power output by the grid-connected inverter, and generating a fundamental voltage control instruction.

[0063] Specifically, the voltage and current output by the inverter are sampled to calculate the active power and reactive power output by the grid-connected inverter. Then, according to the preset droop characteristic curve or equation, the active power P and reactive power Q are used to calculate the frequency f* and amplitude E* of the output voltage to be adjusted. Based on the frequency and amplitude of the output voltage calculated by the droop equation, a fundamental voltage control instruction is generated. This control instruction will be used to adjust the output voltage at the fundamental frequency of the inverter to achieve automatic distribution of active and reactive power and system stability.

[0064] Step S3, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, performing voltage and current double closed-loop control on the composite voltage control instruction, and obtaining a duty cycle signal of the grid-connected inverter.

[0065] As a preferred implementation, step S3 may specifically include the following steps S31 to S35:

[0066] S31, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction.

[0067] The calculation formula of the composite voltage control command is:

[0068] v αβ_m (t) = v αβ_hf (t)+v αβ_p (t)

[0069] In the formula, v αβ_m (t) = [v α_m (t)v β_m (t)] is the composite voltage control vector, v α_m (t) and v β_m (t) are the components of the composite voltage in the α and β directions in the two-phase stationary coordinate system. αβ_hf (t) = [v α_hf (t)v β_hf (t)] is the harmonic voltage compensation control vector, v α_hf (t) and v β_hf (t) are the components of the harmonic voltage compensation control signal in the α and β directions in the two-phase stationary coordinate system. αβ_p (t) = [v α_p (t)v β_p (t)] is the fundamental voltage control vector, v α_p (t) and v β_p (t) are the components of the fundamental voltage control command in the α and β directions in the two-phase stationary coordinate system.

[0070] In this embodiment, the harmonic voltage compensation control instruction and the fundamental voltage control instruction are combined into a composite voltage control instruction, which ensures that the inverter can consider the influence of the fundamental wave and the harmonic wave at the same time during control, thereby achieving accurate control of the output voltage.

[0071] S32, collecting the three-phase voltage output by the grid-connected inverter, and converting it into a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase voltage with the composite voltage control instruction to obtain voltage error information, and inputting the voltage error information into the voltage regulator, and the voltage regulator generates a current reference signal according to the voltage error information.

[0072] The expression of the voltage regulator is:

[0073]

[0074] In the formula, G V (s) represents the transfer function of the voltage regulator, K VP is the proportionality factor of the voltage regulator, K VI is the resonance coefficient of the resonant controller in the voltage regulator, ω c is the bandwidth of the resonant controller in the voltage regulator, ω0 is the fundamental angular frequency, k is the frequency of each resonant control in the resonant controller, and s is a complex variable.

[0075] S33, collecting the three-phase current output by the grid-connected inverter, and converting it to a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase current with the current reference signal output by the voltage regulator, and obtaining a current error signal.

[0076] S34, input the current error signal to the current regulator, and the current regulator generates a modulation signal of the grid-connected inverter according to the current error signal. The current regulator can be expressed as:

[0077] G C (s) = K CP

[0078] Among them, G C (s) is the current regulator transfer function, K CP is the gain of the current regulator.

[0079] S35, inputting the modulation signal output by the current regulator into the modulation circuit, and the modulation circuit generates a duty cycle signal for controlling the inverter switch tube according to the modulation signal.

[0080] In this embodiment, the voltage-current dual closed-loop control strategy enhances the stability of the system, so that the inverter can maintain a stable output when facing grid voltage fluctuations or load changes.

[0081] Compared with the prior art, the droop control type distributed power source harmonic immunity control method provided by the present invention has the following beneficial effects:

[0082] 1) Compared with the existing full-frequency domain control, the present invention uses the harmonic frequency division extraction method to separate and extract only the characteristic subharmonics of the grid connection point. This method can effectively utilize the inverter control bandwidth, reduce the requirements for switching frequency, and thus reduce switching losses and extend the life of the equipment.

[0083] 2) Compared with the existing harmonic current feedback control method, the present invention adopts the harmonic voltage feedforward control method, which will not affect the stability of the system. At the same time, the fundamental wave and the harmonic domain are independently controlled, and there is no coupling interference between them, which further improves the overall control performance and system stability.

[0084] 3) When there is a characteristic sub-harmonic voltage at the grid connection point of the traditional droop control type distributed power supply, the output current will be seriously distorted. The present invention effectively overcomes this problem by introducing the harmonic immunity control method and significantly improves the output current quality of the distributed power supply.

[0085] In a preferred embodiment of the present invention, in order to test the effectiveness of the harmonic immunity control method proposed in the present invention, a nonlinear load is added at the grid connection point. In the embodiment, the distributed power inverter only operates in the traditional droop control mode in the initial stage of the simulation. The simulation is performed until t=0.3s, and the harmonic immunity control method provided by the present invention is added to the inverter control. Figure 3 The current waveform diagram of the distributed power supply output after adopting the harmonic immunity control method of the present invention is shown in FIG. Figure 4 It is the total harmonic distortion of the current output by the distributed power supply after adopting the harmonic immunity control method of the present invention. Figure 3 and Figure 4 It can be seen that before the harmonic immunity control method provided by the present invention is adopted, the harmonic distortion of the output current of the droop control type distributed power supply is serious, up to 30.2%. After the harmonic immunity control method provided by the present invention is adopted, the harmonic distortion rate is reduced to 3.29%.

[0086] Figure 5 The structural block diagram of the droop control type distributed power supply harmonic immune control system provided by the present invention is shown in FIG. Figure 5 The droop control type distributed power source harmonic immunity control system 500 includes:

[0087] The harmonic immunity control module 501 is used to collect the grid connection point voltage, separate the characteristic subharmonic voltage components from the grid connection point voltage by using the harmonic frequency division technology, and generate the harmonic voltage compensation control instruction;

[0088] The fundamental wave droop control module 502 is used to detect the active power and reactive power output by the grid-connected inverter and generate a fundamental wave voltage control instruction;

[0089] The voltage-current dual closed-loop control module 503 is used to synthesize the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, perform voltage-current dual closed-loop control on the composite voltage control instruction, and obtain a duty cycle signal of the grid-connected inverter.

[0090] The droop control type distributed power supply harmonic immune control system provided by the present invention executes the droop control type distributed power supply harmonic immune control method provided by the above-mentioned embodiments through the above-mentioned modules. The droop control type distributed power supply harmonic immune control method has been described in detail in the above-mentioned embodiments, and this embodiment will not be repeated here.

[0091] Figure 6 The structural block diagram of the electronic device provided by the present invention is as follows: Figure 6 As shown, the present invention also provides an electronic device, and the electronic device 600 can be a computing device such as a mobile terminal, a desktop computer, a notebook, a palm computer, and a server. The electronic device 600 includes a processor 601 and a memory 602, wherein the memory 602 stores a droop control type distributed power source harmonic immunity program 606.

[0092] In some embodiments, the memory 602 may be an internal storage unit of a computer device, such as a hard disk or memory of the computer device. In other embodiments, the memory 602 may also be an external storage device of the computer device, such as a plug-in hard disk equipped on the computer device, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Furthermore, the memory 602 may also include both an internal storage unit of the computer device and an external storage device. The memory 602 is used to store application software and various types of data installed on the computer device, such as program codes for installing the computer device. The memory 602 can also be used to temporarily store data that has been output or is to be output. In one embodiment, when the droop-controlled distributed power supply harmonic immunity program 606 is executed by the processor 601, the following steps are implemented:

[0093] S1, collects the grid connection point voltage, uses harmonic frequency division technology to separate the characteristic subharmonic voltage components from the grid connection point voltage, and generates harmonic voltage compensation control instructions;

[0094] S2, detects the active power and reactive power output by the grid-connected inverter and generates fundamental voltage control instructions;

[0095] S3, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, performing voltage and current dual closed-loop control on the composite voltage control instruction, and obtaining a duty cycle signal of the grid-connected inverter.

[0096] In some embodiments, the processor 601 may be a central processing unit (CPU), a microprocessor or other data processing chip, used to run program codes or process data stored in the memory 602, such as executing a droop-controlled distributed power supply harmonic immunity program.

[0097] This embodiment further provides a computer-readable storage medium, on which a droop-controlled distributed power source harmonic immunity program is stored. When the droop-controlled distributed power source harmonic immunity program is executed by a processor, the following steps are implemented:

[0098] S1, collects the grid connection point voltage, uses harmonic frequency division technology to separate the characteristic subharmonic voltage components from the grid connection point voltage, and generates harmonic voltage compensation control instructions;

[0099] S2, detects the active power and reactive power output by the grid-connected inverter and generates fundamental voltage control instructions;

[0100] S3, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, performing voltage and current dual closed-loop control on the composite voltage control instruction, and obtaining a duty cycle signal of the grid-connected inverter.

[0101] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A droop control type distributed power source harmonic immunity control method, characterized in that: include: S1, collects the grid connection point voltage, uses harmonic frequency division technology to separate the characteristic subharmonic voltage components from the grid connection point voltage, and generates harmonic voltage compensation control instructions; S2, detects the active power and reactive power output by the grid-connected inverter and generates fundamental voltage control instructions; S3, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, performing voltage and current dual closed-loop control on the composite voltage control instruction, and obtaining a duty cycle signal of the grid-connected inverter.

2. The droop control type distributed power source harmonic immunity control method according to claim 1, characterized in that: In step S1, generating a harmonic voltage compensation control instruction includes: The harmonic voltage compensation control instruction is calculated based on the characteristic subharmonic voltage components separated by the harmonic frequency division technology and the preset harmonic control gain.

3. The droop control type distributed power source harmonic immunity control method according to claim 2 is characterized in that: The harmonic frequency division technology is implemented by a harmonic frequency divider, which includes a plurality of bandpass filters connected in parallel. The frequency domain expression of the harmonic frequency divider is: Where HF(s) is the frequency domain expression of the harmonic divider, ω cf is the bandwidth of the harmonic divider, h is the harmonic frequency, ω0 is the fundamental angular frequency, and s is a complex variable.

4. The droop control type distributed power source harmonic immunity control method according to claim 1, characterized in that: The calculation formula of the harmonic voltage compensation control instruction is: V hf (s)=V PCC (s)·HF(s)·Q Where V hf (s) is the harmonic voltage compensation control instruction, V PCC (s) is the voltage signal at the grid-connected point of the distributed generation, HF(s) is the frequency domain expression of the harmonic divider, and Q is the harmonic control gain.

5. The droop control type distributed power source harmonic immunity control method according to claim 1, characterized in that: Step S3 specifically includes: S31, synthesizing the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction; S32, collecting the three-phase voltage output by the grid-connected inverter, and converting it into a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase voltage with the composite voltage control instruction to obtain voltage error information, inputting the voltage error information into the voltage regulator, and the voltage regulator generates a current reference signal according to the voltage error information; S33, collecting the three-phase current output by the grid-connected inverter, and converting it into a two-phase stationary coordinate system through coordinate transformation, comparing the converted two-phase current with the current reference signal output by the voltage regulator, and obtaining a current error signal; S34, inputting the current error signal into a current regulator, and the current regulator generates a modulation signal of a grid-connected inverter according to the current error signal; S35, inputting the modulation signal output by the current regulator into the modulation circuit, and the modulation circuit generates a duty cycle signal for controlling the inverter switch tube according to the modulation signal.

6. The droop control type distributed power source harmonic immunity control method according to claim 5, characterized in that: In step S32, the voltage regulator adopts a multi-resonance controller, and the transfer function of the voltage regulator is: In the formula, G V (s) represents the transfer function of the voltage regulator, K VP is the proportionality factor of the voltage regulator, K VI is the resonance coefficient of the resonant controller in the voltage regulator, ω c is the bandwidth of the resonant controller in the voltage regulator, ω0 is the fundamental angular frequency, k is the frequency of each resonant control in the resonant controller, and s is a complex variable.

7. A droop control type distributed power supply harmonic immune control system, characterized in that: include: The harmonic immunity control module is used to collect the grid-connected point voltage, separate the characteristic subharmonic voltage components from the grid-connected point voltage using the harmonic frequency division technology, and generate harmonic voltage compensation control instructions; A fundamental wave droop control module is used to detect the active power and reactive power output by the grid-connected inverter and generate fundamental wave voltage control instructions; The voltage-current dual closed-loop control module is used to synthesize the harmonic voltage compensation control instruction and the fundamental voltage control instruction to obtain a composite voltage control instruction, perform voltage-current dual closed-loop control on the composite voltage control instruction, and obtain a duty cycle signal of the grid-connected inverter.

8. An electronic device, It is characterized in that comprising a memory and a processor, wherein: The memory is used to store programs; The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the droop control type distributed power supply harmonic immunity control method described in any one of claims 1 to 6 above.

9. A computer-readable storage medium, characterized in that: Used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps in the droop-controlled distributed power supply harmonic immunity control method described in any one of claims 1 to 6 above.

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