Converter phase-locked synchronous stability control method and system based on q-axis voltage feedback

Abstract

The present invention discloses a method and system for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback, comprising the following steps: obtaining the q-axis grid-connected point voltage, the d-axis current, and the q-axis current; obtaining a d-axis current command change value based on the q-axis grid-connected point voltage after feedforward control; obtaining a d-axis current reference value based on the d-axis current command change value and the d-axis current steady-state value; obtaining a d-axis potential based on the d-axis current reference value and the d-axis current through negative feedback regulation; obtaining a q-axis potential based on the q-axis current reference value and the q-axis current through negative feedback regulation; and obtaining a modulation signal for controlling the operation of the grid-connected converter based on the d-axis potential and the q-axis potential after coordinate transformation. By adding a control link for the q-axis grid-connected point filtered voltage and the d-axis current command change value, damping is increased, the acceleration process of the PLL is slowed down, and the phase-locked synchronization stability of the grid-connected converter during fault ride-through is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to a converter phase-locked synchronous stabilization control method and system based on q-axis voltage feedback. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Grid-connected converters primarily employ vector control, using the grid-connection point voltage measured by a phase-locked loop (PLL) for vector orientation, achieving decoupled control of the system's output active and reactive power. During fault ride-through, grid voltage drops can reduce the active power transmission capacity between the grid-connected converter and the grid. This can lead to phase-locked synchronization instability caused by active power exceeding the limit, potentially causing widespread disconnection of the grid-connected converter.

[0004] There are two conditions to ensure phase-locked synchronous stability: first, the grid-connected converter has a stable equilibrium point (SEP) during fault ride-through, that is, the system is statically stable; second, the system operating point can transition to the SEP during the dynamic process of PLL, that is, the system is transiently stable (synchronously stable).

[0005] To address static voltage stability, an appropriate current command value can be set during fault ride-through to ensure SEP. Currently, three control methods for ensuring SEP during a grid-connected converter fault include blocking the PLL during grid voltage drops, adjusting the active current reference based on PLL frequency changes, and adjusting the current command based on the grid's Thevenin equivalent parameter during the fault. These methods effectively address SEP.

[0006] However, current research indicates that the dynamic process of phase-locked synchronization is primarily related to the PLL's dynamics when it comes to transient voltage stability. Current research into improving transient stability focuses on two main areas: first, blocking the PLL's integral phase during the fault ride-through dynamics; and second, optimizing PLL control parameters to reduce the integral phase gain or increase the proportional phase gain.

[0007] However, reducing the integral link gain slows down the PLL phase-locking process, hindering stable system operation. A control strategy that uses a fixed active current command value prevents the grid-connected converter from transitioning to the SEP point during the PLL dynamics, leading to the risk of phase-locked synchronization instability and terminal voltage oscillation. This is fundamentally due to the PLL's acceleration area being larger than its deceleration area. Summary of the Invention

[0008] In order to solve the above problems, the present invention proposes a converter phase-locked synchronous stability control method and system based on q-axis voltage feedback. By adding a control link for the q-axis grid-connected point filter voltage and the d-axis current command change value, damping is increased, the acceleration process of the PLL is slowed down, and the phase-locked synchronization stability of the grid-connected converter during fault ride-through is improved.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback, comprising:

[0011] Obtain the q-axis grid connection point voltage, d-axis current, and q-axis current;

[0012] After feedforward control of the q-axis grid-connected point voltage, a d-axis current command change value is obtained, and a d-axis current reference value is obtained according to the d-axis current command change value and the d-axis current steady-state value;

[0013] According to the d-axis current reference value and the d-axis current, the d-axis potential is obtained through negative feedback regulation, and according to the q-axis current reference value and the q-axis current, the q-axis potential is obtained through negative feedback regulation;

[0014] After coordinate transformation of the d-axis potential and the q-axis potential, a modulation signal for controlling the operation of the grid-connected converter is obtained.

[0015] As an optional implementation, the feedforward control process includes: filtering the q-axis grid-connected point voltage, obtaining the d-axis current command change value based on the obtained q-axis grid-connected point filtered voltage and the droop coefficient; adding the d-axis current command change value and the d-axis current steady-state value to obtain the d-axis current reference value.

[0016] As an optional implementation, the q-axis grid-connected point filter voltage and d-axis current command change values ​​are specifically:

[0017]

[0018] Where U q is the voltage at the grid connection point on the q axis; U q ′ is the q-axis grid-connected point filter voltage; Ts is the time constant; K uq It is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage.

[0019] As an optional implementation, the phase-locked synchronous stabilization control method further includes the following:

[0020]

[0021] Where Δω PLLp and Δω PLLi They are the proportional link and the integral link of the phase-locked loop respectively; K p and K i are the proportional coefficient and integral coefficient of the PI controller of the phase-locked loop respectively; I d is the d-axis current; I d0 is the steady-state value of the d-axis current; ω n is the reference frequency; E is the potential in the AC grid, R and L are the resistance and inductance of the AC grid respectively; is the q-axis grid-connected point voltage U q The first-order filter value of ; T is the time constant; δ is the angle of the dq coordinate system relative to the DQ coordinate system; is the first derivative of the angle; K uq U is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage; q ′ is the q-axis grid-connected point filtering voltage.

[0022] As an optional implementation, based on the phase-locked loop motion equation, δ, Δω PLLi and U q ′ is the state variable, and the state space equation is:

[0023]

[0024]

[0025]

[0026] As an optional implementation, after performing coordinate transformation from the dq coordinate system to the three-phase coordinate system based on the d-axis potential and the q-axis potential, the potential on the three-phase coordinate system is obtained, thereby obtaining a modulation signal for controlling the operation of the grid-connected converter.

[0027] In a second aspect, the present invention provides a converter phase-locked synchronous stability control system based on q-axis voltage feedback, comprising:

[0028] an acquisition module configured to acquire a q-axis grid connection point voltage, a d-axis current, and a q-axis current;

[0029] a feedforward control module configured to obtain a d-axis current command change value based on the q-axis grid connection point voltage after feedforward control, and obtain a d-axis current reference value based on the d-axis current command change value and the d-axis current steady-state value;

[0030] a negative feedback regulation module configured to obtain a d-axis potential through negative feedback regulation based on a d-axis current reference value and the d-axis current, and to obtain a q-axis potential through negative feedback regulation based on a q-axis current reference value and the q-axis current;

[0031] The stability control module is configured to obtain a modulation signal for controlling the operation of the grid-connected converter according to coordinate transformation of the d-axis potential and the q-axis potential.

[0032] In a third aspect, the present invention provides an electronic device comprising a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0033] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions, wherein when the computer instructions are executed by a processor, the method described in the first aspect is performed.

[0034] In a fifth aspect, the present invention provides a computer program product, comprising a computer program, which implements the method described in the first aspect when executed by a processor.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] In response to the problem that SEP exists but cannot transition to the SEP point during the dynamic process of PLL, the present invention provides a new phase-locked synchronous stabilization control method for grid-connected converter fault ride-through. Compared with the control strategy in which the active current command is given as a fixed value, by adding a negative feedback control link for the q-axis grid-connected point filter voltage and the d-axis current command change value, it can transition to the SEP point during the dynamic process, significantly enhancing the transient stability of the PLL. In addition, the additional feedforward control is essentially equivalent to increasing damping, slowing down the acceleration process of the PLL, so that the PLL can transition to the SEP point more quickly after a fault occurs, thereby improving the phase-locked synchronization stability during the fault ride-through process of the grid-connected converter.

[0037] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0039] Figure 1 A schematic diagram of a simplified model of a grid-connected converter provided in Example 1 of the present invention;

[0040] Figure 2 A schematic diagram of the positional relationship between the DQ coordinate system and the dq coordinate system provided in Example 1 of the present invention;

[0041] FIG3( a ) is a schematic diagram of a power angle curve in the presence of SEP provided in Example 1 of the present invention;

[0042] FIG3( b ) is a diagram of the fault period u provided in Example 1 of the present invention. q Waveform diagram;

[0043] Figure 4 A block diagram of phase-locked synchronous stabilization control after additional feedforward control provided in Example 1 of the present invention;

[0044] FIG5( a ) is a schematic diagram of the dynamic process after a fault occurs before the additional feedforward control provided by Example 1 of the present invention;

[0045] FIG5( b ) is a schematic diagram of the dynamic process after a fault occurs after the additional feedforward control provided by Example 1 of the present invention;

[0046] Figure 6 A diagram of the simulated power grid topology provided in Example 1 of the present invention;

[0047] FIG7( a ) is a schematic diagram of simulation results of phase-locked synchronization stability before additional feedforward control provided in Example 1 of the present invention;

[0048] FIG7( b ) is a schematic diagram of simulation results of phase-locked synchronization stability after additional feedforward control provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0050] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0051] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "include" and "comprise" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0053] Example 1

[0054] based on Figure 1The figure shows the mechanism of phase-locked synchronization instability. Where U is the voltage vector at the grid connection point, I is the current vector, E is the potential in the AC grid, and R and L are the resistance and inductance of the AC network, respectively.

[0055] Based on the circuit principles:

[0056] U=E+(R+jX)I (1)

[0057] Where X = ω n L,ω n is the system reference frequency.

[0058] To facilitate the analysis of the positional relationship between U and E, a rotating reference coordinate system oriented to E is constructed. The quadrature and direct axes of this rotating coordinate system are represented as the D axis and the Q axis, respectively, where the D axis is always in the same direction as E. The current control of the grid-connected converter is based on the PLL coordinate system, whose quadrature and direct axes are represented as the d axis and the q axis, respectively, and their angles relative to the DQ coordinate system are represented by δ. The positional relationship between the DQ coordinate system and the dq coordinate system is as follows: Figure 2 shown.

[0059] In the dq coordinate system, the current vector of the grid-connected converter is expressed as:

[0060] I=(I d +jI q )e jδ (2)

[0061] Combining formula (1) and formula (2), we can get:

[0062]

[0063] At the equilibrium point of the PLL, U is in the same direction as the d-axis of the PLL, so U q =0, and substituting into formula (3) we can obtain the quasi-steady-state equation for PLL to keep synchronization with the power grid:

[0064] -Esinδ+i d X+i q R=0 (4)

[0065] From formula (4), we can get that the condition for the existence of SEP is |i d X+i q When the influence of AC network resistance is ignored, whether SEP exists is mainly related to the active current, and its active current limit i dmax =E / X. Therefore, setting the current command value of the converter not to exceed the active current limit can ensure the existence of SEP.

[0066] However, in the scenario shown in Figure 3(a), the control strategy of adopting a fixed active current command value will result in the grid-connected converter's system operating point being unable to transition to the SEP point during the PLL dynamic process, which in turn leads to the risk of phase-locked synchronization instability and causes terminal voltage oscillation, as shown in Figure 3(b). The essential reason is that the acceleration area of ​​the PLL is larger than the deceleration area, among which the dominant reason is that the PLL acceleration area is too large.

[0067] Therefore, this embodiment addresses the issue of SEP being present but unable to transition to the SEP point during the PLL dynamic process. By adding a negative feedback control link for the q-axis grid-connected point filter voltage and the d-axis current command change value, damping is increased, slowing the PLL acceleration process and thus improving the phase-locked synchronization stability during the grid-connected converter's fault ride-through process.

[0068] like Figure 4 As shown, specifically including:

[0069] Obtain the q-axis grid connection point voltage, d-axis current, and q-axis current;

[0070] According to the q-axis grid connection point voltage, the d-axis current command change value is obtained after feedforward control;

[0071] According to the d-axis current command change value and the d-axis current steady-state value, a d-axis current reference value is obtained;

[0072] According to the d-axis current reference value and the d-axis current, the d-axis potential is obtained through negative feedback regulation;

[0073] According to the q-axis current reference value and the q-axis current, the q-axis potential is obtained through negative feedback regulation;

[0074] After coordinate transformation of the d-axis potential and the q-axis potential, a modulation signal for controlling the operation of the grid-connected converter is obtained.

[0075] In this embodiment, the feedforward control link includes:

[0076] Filtering the q-axis grid-connected point voltage, and obtaining the d-axis current command change value based on the obtained q-axis grid-connected point filtered voltage and droop coefficient;

[0077] The d-axis current reference value is obtained by adding the d-axis current command change value and the d-axis current steady-state value.

[0078] Specifically expressed as:

[0079]

[0080] Where U q is the voltage at the grid connection point on the q axis; U q ′ is the q-axis grid-connected point filter voltage; Ts is Uq Measuring the time constant of the filter link; K uq is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage; I dref is the d-axis current reference value; I dref0 is the steady-state value of the d-axis current, and is the set value.

[0081] In this embodiment, according to the d-axis current reference value I dref and d-axis current I d After PI negative feedback regulation, the d-axis potential E is obtained d Similarly, according to the q-axis current reference value I qref and q-axis current I q , after PI negative feedback regulation, the q-axis potential E is obtained q Finally, according to the d-axis potential, q-axis potential and angle δ, the coordinate transformation between the dq coordinate system and the three-phase coordinate system is performed to obtain the potential E on the three-phase coordinate system. abc , combined with signal modulation, a PWM modulation signal is obtained to control the operation of the grid-connected converter.

[0082] In addition, when studying the transient stability mechanism of grid-connected systems, the focus is on the control characteristics of the PLL and the external characteristics of the interaction between the system output current and the grid. The regulatory role of the system current inner loop controller is often ignored. Assuming that the actual current can quickly follow its reference value, the following equation is obtained:

[0083]

[0084] In order to analyze the effect of the method of this embodiment on improving the stability of the transient transition process, a PLL-dominated state space equation with additional feedforward control will be established below to analyze its transient stability.

[0085] Combining equations (5)-(6) and the PLL control principle, the complete PLL motion equation after adding the feedforward control link can be obtained:

[0086]

[0087] Where Δω PLLp and Δω PLLi They are the proportional link and the integral link of PLL respectively; K p and K i are the proportional coefficient and integral coefficient of the PI controller of the PLL; I d0 is the steady-state value of the d-axis current; ω n is the system reference frequency; E is the potential in the AC grid, R and L are the resistance and inductance of the AC grid respectively; is the first-order filter of the q-axis grid-connected point voltage; T is the time constant.

[0088] This embodiment method takes into account the first-order filtering of the q-axis grid-connected point voltage, which changes the dimension of the state space equation dominated by PLL. Therefore, this embodiment selects δ, Δω PLLi and U q ′ is used as the state variable, then the state space equation can be obtained as follows:

[0089]

[0090] Where:

[0091]

[0092]

[0093] Based on this state space equation, the dynamic process of the PLL after a fault occurs can be described. By giving different initial states, the dynamic process before and after the additional feedforward control link is compared, and then its transient stability is analyzed, such as Figure 5(a)-Figure 5(b) As shown in Figure 5(a), it can be seen that when a smaller initial value of the PLL output phase angle is given before the additional feedforward control, it cannot transition to the SEP point during the PLL dynamic process, which will cause the risk of phase-locked synchronization instability, as shown in Figure 5(a). After the additional feedforward control is added, the same initial phase angle is given, and it can transition to the SEP point during the dynamic process, significantly enhancing the transient stability of the PLL, as shown in Figure 5(b). In addition, for the initial state that can transition to the SEP point before the additional feedforward control, the additional feedforward control is essentially equivalent to adding damping, which can slow down the acceleration process of the PLL, allowing the PLL to transition to the SEP point more quickly after a fault occurs.

[0094] Compared with the control strategy in which the active current command is given as a fixed value, the active current control method with an additional feedforward control link provided in this embodiment is essentially equivalent to adding damping, which can slow down the acceleration process of the PLL and improve the phase-locked synchronization stability of the grid-connected converter during fault ride-through.

[0095] In order to verify the effectiveness of the proposed control strategy, a simulation model was built in DIgSILENT PowerFactory for simulation verification. Figure 6 As shown in the figure, two transformers boost the 0.69 kV voltage at the grid-connected converter output to 110 kV. This voltage is then connected to the external grid via a long transmission line. When the external grid experiences a voltage amplitude jump, the simulation verifies the synchronization stability between the grid-connected converter and the external grid. The simulation assumes a constant DC bus voltage.

[0096] When the external grid experiences a voltage amplitude jump of 0.3 pu at 0.5 s, the grid-connected converter is made to adopt the traditional control strategy with a fixed active current command value and the active current control strategy with an additional feedforward control link proposed in this embodiment. The simulation results are as follows: Figure 7(a)-Figure 7(b) As shown in the simulation results, it can be seen that when the traditional control strategy is adopted, the speed of the PLL is always greater than 1, which means that the angle difference between the PLL and the external power grid is getting larger and larger, resulting in phase-locked synchronization instability and causing terminal voltage oscillation, as shown in Figure 7(a). When the control strategy proposed in this embodiment is adopted, due to the negative feedback effect of the q-axis voltage and the active current output, the PLL can quickly track the grid phase when the terminal voltage amplitude jumps. Therefore, phase-locked synchronization instability will not occur between the grid-connected converter and the external power grid, and the PLL speed and terminal voltage can remain stable, as shown in Figure 7(b).

[0097] Example 2

[0098] This embodiment provides a converter phase-locked synchronous stability control system based on q-axis voltage feedback, including:

[0099] an acquisition module configured to acquire a q-axis grid connection point voltage, a d-axis current, and a q-axis current;

[0100] a feedforward control module configured to obtain a d-axis current command change value based on the q-axis grid connection point voltage after feedforward control, and obtain a d-axis current reference value based on the d-axis current command change value and the d-axis current steady-state value;

[0101] a negative feedback regulation module configured to obtain a d-axis potential through negative feedback regulation based on a d-axis current reference value and the d-axis current, and to obtain a q-axis potential through negative feedback regulation based on a q-axis current reference value and the q-axis current;

[0102] The stability control module is configured to obtain a modulation signal for controlling the operation of the grid-connected converter according to coordinate transformation of the d-axis potential and the q-axis potential.

[0103] It should be noted that the above modules correspond to the steps described in Example 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the contents disclosed in the above Example 1. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0104] In further embodiments, there is also provided:

[0105] An electronic device includes a memory and a processor, and computer instructions stored in the memory and executed by the processor, wherein when the computer instructions are executed by the processor, the method described in Example 1 is performed. For the sake of brevity, no further details are given here.

[0106] It should be understood that in this embodiment, the processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), off-the-shelf field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0107] The memory may include a read-only memory and a random access memory, and provides instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0108] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the method described in Example 1 is performed.

[0109] The method in Example 1 can be directly implemented as a hardware processor, or can be implemented using a combination of hardware and software modules in the processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, it will not be described in detail here.

[0110] A computer program product includes a computer program, which implements the method described in embodiment 1 when executed by a processor.

[0111] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained in program modules, which are executed in a device on a real or virtual processor of a target to perform the process / method described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided between program modules as needed. The machine-executable instructions for the program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0112] The computer program code for implementing the method of the present invention can be written in one or more programming languages. These computer program codes can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that when the program code is executed by the computer or other programmable data processing device, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on a computer, partially on a computer, as an independent software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0113] In the context of the present invention, computer program code or related data can be carried by any appropriate carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals include electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, and the like.

[0114] Those skilled in the art will appreciate that the units and algorithm steps of the various examples described in conjunction with this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0115] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback, characterized in that: include: Obtain the q-axis grid connection point voltage, d-axis current, and q-axis current; After feedforward control of the q-axis grid-connected point voltage, a d-axis current command change value is obtained, and a d-axis current reference value is obtained according to the d-axis current command change value and the d-axis current steady-state value; According to the d-axis current reference value and the d-axis current, the d-axis potential is obtained through negative feedback regulation, and according to the q-axis current reference value and the q-axis current, the q-axis potential is obtained through negative feedback regulation; After coordinate transformation of the d-axis potential and the q-axis potential, a modulation signal for controlling the operation of the grid-connected converter is obtained; The phase-locked synchronous stabilization control method further includes the following: Where Δω PLLp is the proportional link of the phase-locked loop; Δω PLLi is the integral link of the phase-locked loop; K p and K i are the proportional coefficient and integral coefficient of the PI controller of the phase-locked loop respectively; I d is the d-axis current; I d0 is the steady-state value of the d-axis current; ω n is the reference frequency; E is the potential in the AC grid, R and L are the resistance and inductance of the AC grid respectively; is the q-axis grid-connected point voltage U q The first-order filter value of ; T is the time constant; δ is the angle of the dq coordinate system relative to the DQ coordinate system; is the first derivative of the angle; K uq U is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage; q ′ is the q-axis grid-connected point filtering voltage.

2. The method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback according to claim 1, wherein: The feedforward control process includes: filtering the q-axis grid-connected point voltage, obtaining a d-axis current command change value based on the obtained q-axis grid-connected point filtered voltage and a droop coefficient; and adding the d-axis current command change value and the d-axis current steady-state value to obtain a d-axis current reference value.

3. The method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback according to claim 2, wherein: The specific change values ​​of the q-axis grid-connected point filter voltage and the d-axis current command are: Where U q is the voltage at the grid connection point on the q axis; U q ′ is the q-axis grid-connected point filter voltage; Ts is the time constant; K uq It is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage.

4. The method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback according to claim 1, wherein: Based on the phase-locked loop motion equation, δ, Δω PLLi and U q ′ is the state variable, and the state space equation is:

5. The method for phase-locked synchronous stabilization control of a converter based on q-axis voltage feedback according to claim 1, wherein: According to the d-axis potential and the q-axis potential, after coordinate transformation between the dq coordinate system and the three-phase coordinate system, the potential on the three-phase coordinate system is obtained, thereby obtaining a modulation signal for controlling the operation of the grid-connected converter.

6. A converter phase-locked synchronous stability control system based on q-axis voltage feedback, characterized in that: include: an acquisition module configured to acquire a q-axis grid connection point voltage, a d-axis current, and a q-axis current; The feedforward control module is configured to obtain a d-axis current command change value based on the q-axis grid-connected point voltage after feedforward control, and obtain a d-axis current reference value based on the d-axis current command change value and the d-axis current steady-state value. The motion equation of the grid-connected converter phase-locked loop after feedforward control is: Where Δω PLLp is the proportional link of the phase-locked loop; Δω PLLi is the integral link of the phase-locked loop; K p and K i are the proportional coefficient and integral coefficient of the PI controller of the phase-locked loop respectively; I d is the d-axis current; I d0 is the steady-state value of the d-axis current; ω n is the reference frequency; E is the potential in the AC grid, R and L are the resistance and inductance of the AC grid respectively; is the q-axis grid-connected point voltage U q The first-order filter value of ; T is the time constant; δ is the angle of the dq coordinate system relative to the DQ coordinate system; is the first derivative of the angle; K uq U′ is the droop coefficient between the d-axis current command change value and the q-axis grid-connected point filter voltage; q is the q-axis grid-connected point filtered voltage; a negative feedback regulation module configured to obtain a d-axis potential through negative feedback regulation based on a d-axis current reference value and the d-axis current, and to obtain a q-axis potential through negative feedback regulation based on a q-axis current reference value and the q-axis current; The stability control module is configured to obtain a modulation signal for controlling the operation of the grid-connected converter according to coordinate transformation of the d-axis potential and the q-axis potential.

7. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method according to any one of claims 1 to 5 is completed.

8. A computer-readable storage medium, characterized in that Used to store computer instructions, which, when executed by a processor, complete the method according to any one of claims 1 to 5.

9. A computer program product, characterized in that The invention comprises a computer program, which is used to implement the method according to any one of claims 1 to 5 when the computer program is executed by a processor.

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