Method and system for automatically participating in primary frequency response control by grid-forming grid-connected inverters

Abstract

The present application belongs to the field of distributed power supply control, and particularly relates to a method and system for automatically participating in primary frequency response control of a grid-connected inverter of network construction type. The method mainly comprises a voltage and current inner loop control link, a power synchronization link and a power synchronization compensation link. The voltage and current inner loop control link comprises an inverter voltage and current measurement link, an inverter voltage and current coordinate transformation link, a current inner loop control link and a voltage inner loop control link. The power synchronization link comprises an instantaneous power calculation link, a grid power synchronization link and a voltage, frequency and phase full signal generation link. The power synchronization compensation link design process comprises compensator type selection, real / complex pole compensator parameter selection, power synchronization compensation link embedding in the power synchronization link and verification. The primary frequency response of the control method is a short-term primary frequency response, and is more suitable for distributed power supply inverters with relatively small capacity to realize the primary frequency response function.

Description

Technical Field

[0001] The present invention belongs to the field of distributed power supply control, and in particular relates to a method and system for automatically participating in primary frequency response control of a grid-connected inverter. Background Art

[0002] Distributed power sources, such as distributed photovoltaic devices, typically use a grid-following control scheme. This scheme's advantage lies in its ability to quickly follow the grid's setpoints, effectively implementing maximum power point tracking (MPPT). However, with the increasing number of distributed power sources connected, the grid is losing inertia, and traditional grid-following control is unable to provide primary frequency response for the power system. This leads to greater fluctuations in grid frequency in the event of grid power imbalance, endangering grid stability. Distributed power sources, as typical user-side resources, are currently numerous, but their current level of regulation is low. By improving the control method for distributed power sources from traditional grid-following control to grid-forming control, the distributed power inverters can be given the ability to automatically participate in primary frequency response, thereby providing support for the grid.

[0003] Currently, the typical solution for grid-based control is virtual synchronous generator control, which is well-suited for multi-machine parallel operation scenarios. Its primary frequency response is characterized by a fast response speed and a differential response to output power. For distributed power sources with lower power levels, virtual synchronous generator control means that maximum power point tracking cannot be achieved.

[0004] Patent document CN117639121A proposes a grid-connected control method for photovoltaic inverters. Its key features include the use of virtual synchronous machine control, an active reference current compensation control strategy, and an improved reactive power-voltage control loop to eliminate reactive power distribution deviations caused by line impedance mismatch. However, its disadvantage is that the voltage-source grid-connected inverter cannot automatically return to the differential power tracking mode.

[0005] Patent document CN117060441A proposes a method and system for suppressing active power fluctuations on the AC side of a power synchronous inverter, which can effectively suppress the fluctuations of active power in the power synchronous control of a grid-type inverter. However, it does not solve the problems of long dynamic adjustment time of power following and large adjustment overshoot, and does not address the problem of achieving a primary frequency modulation response function. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for automatically participating in primary frequency response control of a grid-connected inverter to solve the problem in the prior art that virtual synchronous machine control cannot continue to achieve maximum power point tracking for distributed power sources with low power levels.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for automatically participating in primary frequency response control of a grid-connected inverter, comprising:

[0009] Get the instantaneous value u of the three-phase filter capacitor voltage c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Based on the reference phase θ generated by the power synchronization link and the power synchronization compensation link, the instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Perform abc / dq transformation to obtain each dq axis component u c,dq 、i 1,dq ;

[0010] Based on the component u c,dq 、i 1,dq Calculate the instantaneous active power P of the grid-connected inverter o and instantaneous reactive power Q o ;

[0011] The instantaneous active power P o The first error signal is obtained by subtracting the active power reference value; the instantaneous reactive power Q o Subtract the first error signal from the reactive power reference value to obtain a second error signal; send the first error signal to the active power synchronization link to obtain a frequency deviation compensation signal Δω; send the second error signal to the reactive power synchronization link to obtain a voltage deviation compensation signal ΔU;

[0012] Add the frequency deviation compensation signal Δω to the reference frequency ω0 to obtain the full frequency signal ω. Integrate the full frequency signal ω to obtain the reference phase θ as the input of the coordinate transformation link; add ΔU to the reference voltage U0 to obtain the three-phase voltage amplitude full signal u cd * As the voltage inner loop reference input;

[0013] The three-phase voltage amplitude full signal u cd * and the d-axis voltage component u c,d The difference is sent to the voltage inner loop PI regulator to obtain the d-axis inner loop reference current; based on the d-axis voltage component u c,d Get the d-axis decoupling current;

[0014] The three-phase voltage amplitude full signal u cq * and the q-axis voltage component u c,q The difference is sent to the voltage inner loop PI regulator to obtain the q-axis inner loop reference current; based on the q-axis voltage component u c,q Get the q-axis decoupling current;

[0015] The q-axis decoupling current, the d-axis inner loop reference current, and the d-axis component i of the grid-side inductance current are summed up 2d to obtain a d-axis current inner loop reference value; the d-axis current inner loop reference value is subtracted from the d-axis current component i 1,d to obtain a difference value; the difference value is input into a first proportional regulator to obtain a first proportional regulator output value;

[0016] The q-axis inner loop reference current and the q-axis component i of the grid-side inductance current are summed up 2q to obtain a q-axis current inner loop reference value; the q-axis current inner loop reference value is subtracted from the q-axis current component i 1,q to obtain a difference value; the difference value is input into a second proportional regulator to obtain a second proportional regulator output value;

[0017] The d-axis current component i 1,d is used to obtain a d-axis decoupling voltage; the q-axis current component i 1,q is used to obtain a q-axis decoupling voltage;

[0018] The first proportional regulator output value, the d-axis voltage component u c,d and the q-axis decoupling voltage are summed up to obtain a modulation voltage d-axis component;

[0019] The second proportional regulator output value, the q-axis voltage component u c,q is summed up, and the d-axis decoupling voltage is subtracted to obtain a modulation voltage q-axis component;

[0020] The modulation voltage d-axis component and the modulation voltage q-axis component are subjected to dq / abc conversion to obtain a three-phase modulation voltage.

[0021] Further, the three-phase voltage amplitude full signal u c,abc is used to obtain a machine-side filter inductance instantaneous current value i 1,abc is an electrical parameter collected at an LCL filter of a grid-connected inverter.

[0022] Further, the three-phase voltage amplitude full signal u cq * is set to 0.

[0023] Further, the first error signal is input into an active synchronous link to obtain a frequency deviation compensation signal Δω; wherein:

[0024] The active synchronous link comprises a proportional integral regulator link and a compensator link;

[0025] After the first error signal passes through the proportional integral regulator link, the first error signal enters the compensator link to obtain the frequency deviation compensation signal Δω.

[0026] Further, in the compensator link, a real pole compensator or a complex pole compensator is selected.

[0027] Furthermore, the power output equation of the grid-connected inverter is:

[0028]

[0029] Among them, θ g is the grid phase, U o is the inverter output voltage amplitude, U g is the grid voltage amplitude, X l is the inductive reactance corresponding to the grid-side inductance in the LCL filter; θ is the inverter phase.

[0030] A second aspect of the present invention provides a method for automatically participating in primary frequency response control of a grid-connected inverter, comprising:

[0031] Grid-connected inverter voltage and current inner loop control: A dual closed-loop controller is used to control the dq components of the instantaneous current value of the machine-side filter inductor and the dq components of the instantaneous voltage value of the filter capacitor respectively;

[0032] Power synchronization link of grid-connected inverter: coordinate transformation reference phase and voltage amplitude offset correction are obtained through output power calculation to achieve synchronization between the inverter and the grid;

[0033] Power synchronization compensation link of grid-connected inverter: compensates and improves the signal obtained in the power synchronization link in the frequency domain.

[0034] Furthermore, the method specifically includes:

[0035] Inverter voltage and current measurement link: measure the instantaneous value u of the three-phase filter capacitor voltage on the distributed power inverter LCL filter c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc ;

[0036] Inverter voltage and current coordinate transformation link: The reference phase θ generated by the power synchronization link and the power synchronization compensation link is transformed into the two-phase synchronous rotating coordinate system through the three-phase static-two-phase synchronous rotating coordinate transformation to transform the instantaneous value of the three-phase filter capacitor voltage and the instantaneous current value of the machine-side filter inductor. The corresponding variable is named u c,dq 、i 1,dq ;

[0037] Current inner loop control link: adopt proportional control to achieve i 1,dq Control of instantaneous value, the control output is used as the input of the inverter PWM modulation link;

[0038] Voltage inner loop control link: adopt proportional-integral control to achieve u c,dq Control of instantaneous value, the control output serves as the input of the current inner loop.

[0039] In a third aspect, the application provides an electronic device comprising a processor and a memory, wherein the processor is configured to execute a computer program stored in the memory to implement the method for automatically participating in primary frequency response control of grid-forming grid-connected inverters as described above.

[0040] In a fourth aspect, the application provides a computer-readable storage medium storing at least one instruction, wherein the at least one instruction is configured to be executed by a processor to implement the method for automatically participating in primary frequency response control of grid-forming grid-connected inverters as described above.

[0041] Compared with the prior art, the application has the following advantages:

[0042] Compared with the prior art, the grid-forming distributed power inverter based on power synchronization provided by the application can automatically recover to the original power difference-free state after the end of the primary frequency response process, and is more suitable for small and medium power distributed power scenarios. The traditional power synchronization control has poor dynamic response, and a power synchronization compensation controller needs to be designed to shorten the power synchronization adjustment time and reduce the power synchronization overshoot.

[0043] In the application, the grid-forming control scheme based on power synchronization is adopted. Since the PI regulator exists in the power loop, the power reference follows without static error during the grid-connected operation of the grid-forming inverter, and the grid-forming inverter is more suitable for distributed power inverters that need to continuously use the MPPT scheme in the preceding sequence.

[0044] In the application, the real pole compensator and the complex pole compensator of the power synchronization link are designed, both of which are second-order lead-lag links. The real pole compensator is characterized by strong robustness to model gain, and the complex pole compensator is characterized by strong robustness to time delay of the control system. Both of them can improve the performance of the power synchronization link, shorten the dynamic adjustment time, and reduce the step response overshoot.

[0045] In the application, the parameter selection principle of the two types of power synchronization compensators is given. The parameters selected according to the principle can simultaneously improve the adjustment dynamics of the power synchronization link and the primary frequency response. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings, which form a part of the present description, illustrate the present application and together with the written description serve to explain the principles of the application. In the drawings:

[0047] Figure 1 FIG. 1 is a schematic diagram of an inverter control system structure in an embodiment of the application;

[0048] Figure 2Schematic diagram of a power synchronous compensation control method for a grid-type distributed power inverter according to an embodiment of the present invention;

[0049] Figure 3 This is a structural diagram of a grid-type distributed power inverter automatically participating in a primary frequency modulation response system in an embodiment of the present invention;

[0050] Figure 4 The figure is a comparison diagram of the output power dynamics of the proposed grid-connected distributed power inverter, the output power dynamics of the traditional grid-following inverter, and the output power dynamics of the virtual synchronous machine method under the condition of grid frequency changes in the embodiment of the present invention.

[0051] Figure 5 This is a structural block diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0053] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise indicated, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0054] Example 1

[0055] The present invention provides a method and system for automatically participating in primary frequency response control of a grid-connected distributed power inverter. The invented control method and system mainly include a voltage and current inner loop control link of the grid-connected inverter, a power synchronization link of the grid-connected inverter, and a power synchronization compensation link of the grid-connected inverter. The voltage and current inner loop control link of the grid-connected inverter includes four main links: an inverter voltage and current measurement link, an inverter voltage and current coordinate transformation link, a current inner loop control link, and a voltage inner loop control link. The power synchronization link of the grid-connected inverter includes three main links: an instantaneous power calculation link, a power grid power synchronization link, and a voltage, frequency, and phase full signal generation link. The design process of the power synchronization compensation link of the grid-connected inverter includes three main steps: compensator type selection, real / complex pole compensator parameter selection, embedding the power synchronization compensation link into the power synchronization loop, and verification. The control method described in the present invention and the virtual synchronous machine control method both have primary frequency response capabilities. The difference is that the primary frequency response of the control method described in the present invention is a short-term primary frequency response, which is more suitable for distributed power inverters with relatively small storage capacity to achieve primary frequency response functions.

[0056] like Figure 1 As shown, a method for automatically participating in primary frequency response control of a grid-connected inverter of a grid-connected type includes:

[0057] Get the instantaneous value u of the three-phase filter capacitor voltage c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Based on the reference phase θ generated by the power synchronization link and the power synchronization compensation link, the instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Perform abc / dq transformation to obtain each dq axis component u c,dq 、i 1,dq ;

[0058] Based on the component u c,dq 、i 1,dq Calculate the instantaneous active power P of the grid-connected inverter o and instantaneous reactive power Q o ;

[0059] The instantaneous active power P o The first error signal is obtained by subtracting the active power reference value; the instantaneous reactive power Q o Subtract the first error signal from the reactive power reference value to obtain a second error signal; send the first error signal to the active power synchronization link to obtain a frequency deviation compensation signal Δω; send the second error signal to the reactive power synchronization link to obtain a voltage deviation compensation signal ΔU;

[0060] Add the frequency deviation compensation signal Δω to the reference frequency ω0 to obtain the full frequency signal ω. Integrate the full frequency signal ω to obtain the reference phase θ as the input of the coordinate transformation link; add ΔU to the reference voltage U0 to obtain the three-phase voltage amplitude full signal u cd * As the voltage inner loop reference input;

[0061] The three-phase voltage amplitude full signal u cd * and the d-axis voltage component u c,d The difference is sent to the voltage inner loop PI regulator to obtain the d-axis inner loop reference current; based on the d-axis voltage component u c,d Get the d-axis decoupling current;

[0062] The three-phase voltage amplitude full signal u cq * and the q-axis voltage component u c,q The difference is sent to the voltage inner loop PI regulator to obtain the q-axis inner loop reference current; based on the q-axis voltage component u c,q Get the q-axis decoupling current;

[0063] The q-axis decoupling current, the d-axis inner loop reference current and the grid-side inductor current d-axis component i 2d Sum the d-axis current inner loop reference value and add the d-axis current inner loop reference value to the d-axis current component i 1,d The difference is sent to the first proportional regulator to obtain the output value of the first proportional regulator;

[0064] The q-axis inner loop reference current and the grid-side inductor current q-axis component i 2q Sum and subtract from the d-axis decoupling current to obtain the q-axis current inner loop reference value; compare the q-axis current inner loop reference value with the q-axis current component i 1,q The difference is sent to the second proportional regulator to obtain the output value of the second proportional regulator;

[0065] Based on the d-axis current component i 1,d Get the d-axis decoupling voltage; based on the q-axis current component i 1,q Get the q-axis decoupling voltage;

[0066] The output value of the first proportional regulator, the d-axis voltage component u c,d The modulation voltage d-axis component is obtained by summing it with the q-axis decoupling voltage;

[0067] The second proportional regulator output value, q-axis voltage component u c,q Sum and subtract from the d-axis decoupling voltage to obtain the q-axis component of the modulation voltage;

[0068] Perform dq / abc transformation on the d-axis component and the q-axis component of the modulation voltage to obtain a three-phase modulation voltage.

[0069] Optionally, the instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc These are the electrical parameters collected at the LCL filter of the grid-connected inverter.

[0070] Optionally, the three-phase voltage amplitude full signal u cq * Set to 0.

[0071] Optionally, the first error signal is sent to the active synchronization link to obtain a frequency deviation compensation signal Δω; wherein:

[0072] The active synchronization link includes the proportional integral regulator link and the compensator link;

[0073] After passing through the proportional-integral regulator link, the first error signal enters the compensator link to obtain the frequency deviation compensation signal Δω.

[0074] Optionally, in the compensator link, a real pole compensator or a complex pole compensator is selected.

[0075] Optionally, the power output equation of the grid-connected inverter is:

[0076]

[0077] Among them, θ g is the grid phase, U o is the inverter output voltage amplitude, U g is the grid voltage amplitude, X l is the inductive reactance corresponding to the grid-side inductance in the LCL filter; θ is the inverter phase.

[0078] In order to further explain and illustrate the present invention, some other embodiments further provide a method for automatically participating in primary frequency response control of a grid-connected inverter, including:

[0079] Grid-connected inverter voltage and current inner loop control: A dual closed-loop controller is used to control the dq components of the instantaneous current value of the machine-side filter inductor and the dq components of the instantaneous voltage value of the filter capacitor respectively;

[0080] Power synchronization link of grid-connected inverter: coordinate transformation reference phase and voltage amplitude offset correction are obtained through output power calculation to achieve synchronization between the inverter and the grid;

[0081] Power synchronization compensation link of grid-connected inverter: compensates and improves the signal obtained in the power synchronization link in the frequency domain.

[0082] In the above method, the voltage and current inner loop control of the grid-connected inverter specifically includes:

[0083] S10 inverter voltage and current measurement link: measure the instantaneous value u of the three-phase filter capacitor voltage on the distributed power inverter LCL filter c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc .

[0084] S20 inverter voltage and current coordinate transformation link: The reference phase θ generated by the power synchronization link and the power synchronization compensation link is transformed into the two-phase synchronous rotating coordinate system through the three-phase static-two-phase synchronous rotating coordinate transformation (abc / dq transformation) to transform the instantaneous value of the three-phase filter capacitor voltage and the instantaneous current value of the machine-side filter inductor into the two-phase synchronous rotating coordinate system. The corresponding variable is named u c,dq 、i 1,dq .

[0085] S30 current inner loop control link: adopts proportional control to achieve i 1,dq The instantaneous value is controlled, and the control output is used as the input of the inverter PWM modulation link.

[0086] S40 voltage inner loop control link: adopts proportional-integral control to achieve u c,dq Control of instantaneous value, the control output serves as the input of the current inner loop.

[0087] In the above method, the power synchronization link of the grid-connected inverter specifically includes:

[0088] S1 instantaneous power calculation: According to u c,abc with i 1,abc The instantaneous output active power P of the grid-connected inverter is calculated as follows: o and reactive power Q o .

[0089] S2 grid power synchronization link: Based on the output active power and reactive power, the proportional-integral (PI) regulator generates the frequency deviation compensation signal Δω and the voltage deviation compensation signal ΔU

[0090] S3 voltage, frequency and phase full signal generation: Add Δω to the reference frequency ω0 to obtain the frequency full signal ω, integrate the frequency full signal to obtain the reference phase θ as the input of the coordinate transformation link; add ΔU to the reference voltage U0 to obtain the three-phase voltage amplitude full signal u cd * As the voltage inner loop reference input (u cq * Set to 0).

[0091] In the above method, the power synchronous compensation link of the grid-connected inverter includes the following steps:

[0092] S101 compensator type selection: Select either a real-pole compensator or a complex-pole compensator based on the application scenario. Real-pole compensators offer greater gain robustness, while complex-pole compensators offer greater lag robustness.

[0093] S201 real pole compensator parameter selection: In the real pole compensator, T1, T2, T3, K c Four compensator time constant parameters, where T1>T2>T3>0, and T1=0.5T f , T2=0.1T1, T3=0.5T2, selected as half of the inner loop time constant. K c The initial value is 1.0, and the compensator gain K is adjusted c Fine-tuning around 1.0 is used to adjust the dynamic response time. The final compensator transfer function is:

[0094]

[0095] S202 complex pole compensator parameter selection: damping ratio ζ is selected as 0.707, ω dThe selected solution is ω d =5 / T f , T f is the inner loop time constant. T n The selected solution is T n =1 / (5ω z ),ω z Defined as the power synchronous PI regulator integral gain k i With proportional gain k p After selecting the parameters, fine-tune T n With ω d , so that the four intersection points of the optimal gain line and the root locus in the overall transfer function of the compensated power synchronization link are located at the same gain of the root locus, calculate the gain value, and use it as K c The final compensator transfer function is:

[0096]

[0097] S301 The power synchronization compensation link is embedded in the power synchronization loop: After the link designed in step S2 is embedded in the power synchronization link, it is put into the actual system after being verified by frequency domain and simulation.

[0098] By adopting the power synchronization link and the power synchronization compensation link, the grid-type distributed power inverter has the ability to automatically participate in the primary frequency response.

[0099] In an optional embodiment, a grid-type distributed power inverter automatically participates in a primary frequency response control system, comprising:

[0100] Inverter voltage and current measurement module: measures the instantaneous value u of the three-phase filter capacitor voltage on the distributed power inverter LCL filter c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc ;

[0101] Grid-connected distributed power inverter controller: a device used to realize the control functions of the voltage and current inner loop control link of the grid-connected inverter, the power synchronization link of the grid-connected inverter, the power synchronization compensation link of the grid-connected inverter and the inverter PWM modulation link.

[0102] The functional links implemented by the grid-type distributed power inverter controller include:

[0103] Voltage and current inner loop control link: adopts current control scheme to set the initial stable operating state of the inverter.

[0104] Power synchronization link of grid-connected inverter: The power synchronization link of grid-connected inverter: The coordinate transformation reference phase and voltage amplitude offset correction are obtained through output power calculation to achieve synchronization between the inverter and the grid;

[0105] Power synchronization compensation link of grid-connected inverter: compensate and improve the signal obtained in the power synchronization link in the frequency domain;

[0106] Inverter PWM modulation link: the link that converts the calculated digital signal into a PWM control signal.

[0107] Specifically, if Figure 1 and Figure 2 As shown, the present invention aims to improve the control loop in the original grid-type inverter to realize the automatic participation of the grid-type distributed power inverter in the primary frequency response control method. Figure 1 、 2 in,i 1,abc 、u c,abc 、i 1,dq 、u c,dq are the instantaneous current value of the machine-side filter inductor and the instantaneous voltage value of the three-phase filter capacitor and the corresponding dq coordinate system variables, θ is the phase required for coordinate transformation, ω is the inverter output voltage frequency, P o 、P ref are the inverter output active power and active power reference, Q o , Q ref are the inverter output reactive power and reactive power reference respectively, L1 and C1 are the LCL filter machine side inductance and filter capacitor respectively, G PI (s) is the voltage inner loop PI regulator transfer function, k pin is the current inner loop proportional gain. In the control mode of the grid-type inverter, the inverter power output equation is:

[0108]

[0109] Among them, θ g is the grid phase, U o is the inverter output voltage amplitude, which is equivalent to the LCL filter capacitor voltage amplitude in the present invention, U g is the grid voltage amplitude, X l is the inductive reactance corresponding to the grid-side inductance in the LCL filter. According to the above inverter power output equation, the output active power of the grid-connected inverter is directly affected by the phase difference θ-θ between the inverter and the grid connection point. g The output reactive power is determined by the voltage amplitude difference U between the inverter output port voltage and the grid connection point. o -U g Therefore, through Figure 2The designed PI regulator link can realize the temporary rise of the output active power when the grid frequency and phase angle change while realizing the active and reactive error following of the inverter output.

[0110] In contrast, the virtual synchronous machine method adopted by the patent 1 in the background art is essentially equivalent to using a P regulator in the power synchronization loop, and the proportional gain is essentially the power droop coefficient. The difference between the two is that due to the droop characteristic of the virtual synchronous machine, the deviation between the output power and the reference value (i.e. P ref -P o ) is proportional to the deviation of the actual grid frequency, and the proportional coefficient is the droop coefficient. This characteristic is more suitable for large virtual synchronous machines with long-term support capability, but for distributed power inverters with generally smaller capacity, limited individual support capability, and relying on cluster control for regulation effect, it is more suitable to use the power synchronization method adopted in this paper, which realizes power error-free tracking and distributed power MPPT control while providing temporary and limited support for the grid.

[0111] The automatic primary frequency response control method of the grid-constructed distributed power inverter, the virtual synchronous machine control method and the grid-following inverter control method described in the present application will be compared below to illustrate the characteristics of the method in this paper. Figure 3 To verify the method described in the simulation system, Figure 4 The primary frequency response simulation results when the grid frequency drops under the three control methods, and the parameters of the inverter under the three control methods are basically the same.

[0112] From Figure 4 It can be seen that when the grid frequency fluctuates, the grid-following control method cannot realize automatic primary frequency response, while the VSG and the power synchronization control method described in the present application can realize automatic frequency response. However, the response modes of the two are different. When the frequency fluctuation occurs, the VSG output power automatically increases, but it will not return to the original power reference value. Under the power synchronization control scheme with real pole compensator, when the grid frequency fluctuates, the output power will automatically increase to provide certain frequency support for the grid, but then the output power will return to the original reference power level. The compensation effect of the complex pole compensator described in the present application is similar, so it is not reflected in the figure. Through simulation comparison, it can be concluded that the control method described in the present application will be more suitable for the control of grid-constructed distributed power with small capacity or almost no independent energy storage system, which can enable the distributed power to provide certain primary frequency response capability for the grid while minimizing the impact on its own maximum power point tracking operation.

[0113] The proposed grid-connected distributed power inverter based on power synchronization automatically returns to its original power-free state after a frequency response process, making it more suitable for small and medium-power distributed power scenarios. Conventional power synchronization control, however, suffers from poor dynamic response and requires the design of a power synchronization compensation controller to shorten power synchronization adjustment time and reduce power synchronization overshoot.

[0114] Example 2

[0115] like Figure 5 As shown, the present invention also provides an electronic device 100 for implementing the method for automatically participating in primary frequency response control of a grid-connected inverter in the above-mentioned embodiment 1;

[0116] The electronic device 100 includes a memory 101 , at least one processor 102 , a computer program 103 stored in the memory 101 and executable on the at least one processor 102 , and at least one communication bus 104 .

[0117] The memory 101 can be used to store a computer program 103. The processor 102 implements the steps of a method for automatically participating in a primary frequency response control of a grid-connected inverter in Example 1 by running or executing the computer program stored in the memory 101 and calling data stored in the memory 101.

[0118] The memory 101 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data (such as audio data) created according to the use of the electronic device 100. In addition, the memory 101 may include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device.

[0119] The at least one processor 102 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 may be a microprocessor or any conventional processor. The processor 102 is the control center of the electronic device 100 and connects various parts of the entire electronic device 100 using various interfaces and lines.

[0120] The memory 101 in the electronic device 100 stores a plurality of instructions to implement a method for automatically participating in a primary frequency response control of a grid-connected inverter. The processor 102 can execute the plurality of instructions to implement:

[0121] Get the instantaneous value u of the three-phase filter capacitor voltage c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Based on the reference phase θ generated by the power synchronization link and the power synchronization compensation link, the instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Perform abc / dq transformation to obtain each dq axis component u c,dq 、i 1,dq ;

[0122] Based on the component u c,dq 、i 1,dq Calculate the instantaneous active power P of the grid-connected inverter o and instantaneous reactive power Q o ;

[0123] The instantaneous active power P o The first error signal is obtained by subtracting the active power reference value; the instantaneous reactive power Q o Subtract the first error signal from the reactive power reference value to obtain a second error signal; send the first error signal to the active power synchronization link to obtain a frequency deviation compensation signal Δω; send the second error signal to the reactive power synchronization link to obtain a voltage deviation compensation signal ΔU;

[0124] Add the frequency deviation compensation signal Δω to the reference frequency ω0 to obtain the full frequency signal ω. Integrate the full frequency signal ω to obtain the reference phase θ as the input of the coordinate transformation link; add ΔU to the reference voltage U0 to obtain the three-phase voltage amplitude full signal ucd * As the voltage inner loop reference input;

[0125] The three-phase voltage amplitude full signal u cd * and the d-axis voltage component u c,d The difference is sent to the voltage inner loop PI regulator to obtain the d-axis inner loop reference current; based on the d-axis voltage component u c,d Get the d-axis decoupling current;

[0126] The three-phase voltage amplitude full signal u cq * and the q-axis voltage component u c,q The difference is sent to the voltage inner loop PI regulator to obtain the q-axis inner loop reference current; based on the q-axis voltage component u c,q Get the q-axis decoupling current;

[0127] The q-axis decoupling current, the d-axis inner loop reference current and the grid-side inductor current d-axis component i 2d Sum the d-axis current inner loop reference value and add the d-axis current inner loop reference value to the d-axis current component i 1,d The difference is sent to the first proportional regulator to obtain the output value of the first proportional regulator;

[0128] The q-axis inner loop reference current and the grid-side inductor current q-axis component i 2q Sum and subtract from the d-axis decoupling current to obtain the q-axis current inner loop reference value; compare the q-axis current inner loop reference value with the q-axis current component i 1,q The difference is sent to the second proportional regulator to obtain the output value of the second proportional regulator;

[0129] Based on the d-axis current component i 1,d Get the d-axis decoupling voltage; based on the q-axis current component i 1,q Get the q-axis decoupling voltage;

[0130] The output value of the first proportional regulator, the d-axis voltage component u c,d The modulation voltage d-axis component is obtained by summing it with the q-axis decoupling voltage;

[0131] The second proportional regulator output value, q-axis voltage component u c,q Sum and subtract from the d-axis decoupling voltage to obtain the q-axis component of the modulation voltage;

[0132] Perform dq / abc transformation on the d-axis component and the q-axis component of the modulation voltage to obtain a three-phase modulation voltage.

[0133] Example 4

[0134] If the module / unit integrated in the electronic device 100 is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. Computer-readable media may include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory and read-only memory (ROM, Read-Only Memory).

[0135] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0136] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0137] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0138] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0139] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for automatically participating in primary frequency response control of a grid-connected inverter, characterized in that: include: Get the instantaneous value u of the three-phase filter capacitor voltage c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Based on the reference phase θ generated by the power synchronization link and the power synchronization compensation link, the instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc Perform abc / dq transformation to obtain each dq axis component u c,dq 、i 1,dq ; Based on the component u c,dq 、i 1,dq Calculate the instantaneous active power P of the grid-connected inverter o and instantaneous reactive power Q o ; The instantaneous active power P o The first error signal is obtained by subtracting the active power reference value; the instantaneous reactive power Q o Subtract the first error signal from the reactive power reference value to obtain a second error signal; send the first error signal to the active power synchronization link to obtain a frequency deviation compensation signal Δω; send the second error signal to the reactive power synchronization link to obtain a voltage deviation compensation signal ΔU; Add the frequency deviation compensation signal Δω to the reference frequency ω0 to obtain the full frequency signal ω. Integrate the full frequency signal ω to obtain the reference phase θ as the input of the coordinate transformation link; add ΔU to the reference voltage U0 to obtain the three-phase voltage amplitude full signal u cd * As the voltage inner loop reference input; The three-phase voltage amplitude full signal u cd * and the d-axis voltage component u c,d The difference is sent to the voltage inner loop PI regulator to obtain the d-axis inner loop reference current; based on the d-axis voltage component u c,d Get the d-axis decoupling current; The three-phase voltage amplitude full signal u cq * and the q-axis voltage component u c,q The difference is sent to the voltage inner loop PI regulator to obtain the q-axis inner loop reference current; based on the q-axis voltage component u c,q Get the q-axis decoupling current; The q-axis decoupling current, the d-axis inner loop reference current and the grid-side inductor current d-axis component i 2d Sum and get the inner loop reference value of d-axis current; The d-axis current inner loop reference value and the d-axis current component i 1,d The difference is sent to the first proportional regulator to obtain the output value of the first proportional regulator; The q-axis inner loop reference current and the grid-side inductor current q-axis component i 2q Sum and subtract the current from the d-axis decoupling current to obtain the q-axis current inner loop reference value; The q-axis current inner loop reference value and the q-axis current component i 1,q The difference is sent to the second proportional regulator to obtain the output value of the second proportional regulator; Based on the d-axis current component i 1,d Get the d-axis decoupling voltage; based on the q-axis current component i 1,q Get the q-axis decoupling voltage; The output value of the first proportional regulator, the d-axis voltage component u c,d The modulation voltage d-axis component is obtained by summing it with the q-axis decoupling voltage; The second proportional regulator output value, q-axis voltage component u c,q Sum and subtract from the d-axis decoupling voltage to obtain the q-axis component of the modulation voltage; Perform dq / abc transformation on the d-axis component and the q-axis component of the modulation voltage to obtain a three-phase modulation voltage.

2. The method for automatically participating in primary frequency response control of a grid-connected inverter according to claim 1, characterized in that: The instantaneous value of the three-phase filter capacitor voltage u c,abc and the instantaneous current value i of the filter inductor on the machine side 1,abc These are the electrical parameters collected at the LCL filter of the grid-connected inverter.

3. The method for automatically participating in primary frequency response control of a grid-connected inverter according to claim 1, characterized in that: Three-phase voltage amplitude full signal u cq * Set to 0.

4. The method for automatically participating in primary frequency response control of a grid-connected inverter according to claim 1, characterized in that: The first error signal is sent to the active synchronization link to obtain the frequency deviation compensation signal Δω; where: The active synchronization link includes the proportional integral regulator link and the compensator link; After passing through the proportional-integral regulator link, the first error signal enters the compensator link to obtain the frequency deviation compensation signal Δω.

5. The method for automatically participating in primary frequency response control of a grid-connected inverter according to claim 4, characterized in that: In the compensator link, a real pole compensator or a complex pole compensator is selected.

6. The method for automatically participating in primary frequency response control of a grid-connected inverter according to claim 1, characterized in that: The power output equation of the grid-type inverter is: Among them, θ g is the grid phase, U o is the inverter output voltage amplitude, U g is the grid voltage amplitude, X l is the inductive reactance corresponding to the grid-side inductance in the LCL filter; θ is the inverter phase.

7. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the method for automatically participating in primary frequency response control of a grid-connected inverter according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by the processor, the method for automatically participating in primary frequency response control of a grid-connected inverter according to any one of claims 1 to 6 is implemented.

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