A small signal stability evaluation method, system and electronic equipment of a high-voltage direct-current transmission inverter side receiving end system and a computer readable storage medium

Abstract

The present application relates to a kind of high voltage direct current transmission inverter side receiving end system small signal stability evaluation method, system, electronic equipment and computer readable storage medium, wherein method includes: gathering commutation bus steady-state operating parameter to construct inverter side nonlinear control equation group;Small disturbance response characteristics are extracted at system steady-state operating point, and linear equation group is established;Linear equation group is decoupled in combination with feedback control loop parameter, and aggregated to build transfer function admittance model;Based on the model, time-domain dynamic response curve is obtained, and the small signal stability evaluation index of system is output.The present application avoids complex electromagnetic transient modeling process, can intuitively, accurately reflect the time sequence dynamic characteristics of system under actual power grid fluctuation, greatly improve the efficiency of small signal stability analysis and evaluation of direct current transmission system.

Description

Technical Field

[0001] This invention belongs to the field of power grid stability analysis technology, specifically relating to a method, system, electronic equipment, and computer-readable storage medium for small-disturbance stability assessment of a high-voltage direct current transmission inverter-side receiving-end system. Background Technology

[0002] Long-distance, high-capacity high-voltage direct current (HVDC) transmission technology plays a crucial role in the interconnection and configuration of modern power grids. With the increasing complexity of power grid structures, HVDC transmission systems exhibit numerous control variables and significant nonlinear characteristics. The operating state of the inverter-side receiving-end system has a decisive impact on the safety and stability of the entire AC / DC hybrid power grid. To deeply explore and prevent system oscillations and instability risks, a rigorous small-disturbance stability assessment of the HVDC receiving-end system is essential.

[0003] When conducting small-disturbance stability analysis, constructing a mathematical model that can accurately reflect the dynamic characteristics of the system is a key prerequisite. However, in practical applications, existing high-voltage direct current transmission system modeling methods often face a dilemma.

[0004] On the one hand, the simplified model based on the quasi-steady-state assumption is mainly applicable to static analysis. In essence, it is only a special case of the small disturbance model in the zero frequency band, completely stripping away the dynamic adjustment process of the system controller, which makes it impossible to truly reflect the dynamic evolution characteristics of the system when it is disturbed.

[0005] On the other hand, to compensate for the shortcomings of quasi-steady-state models, existing technologies tend to use electromagnetic transient modeling methods to characterize complex control dynamics. However, due to the high coupling between the physical process of AC / DC power conversion on the inverter side and feedback regulation loops such as phase-locked loops and constant voltage control, the established equation set is extremely complex. This highly coupled mathematical structure necessitates reliance on cumbersome time-domain simulations for analyzing small disturbances. Not only is the electromagnetic transient modeling process exceptionally complex and computationally resource-intensive, but it also makes it difficult to directly and flexibly achieve equivalent integration with the mathematical models of external AC power grids.

[0006] Therefore, there is an urgent need for a solution that can accurately separate control dynamic and steady-state network parameters, eliminate the dependence on complex electromagnetic transient modeling, and thus improve the efficiency of stability analysis of high-voltage direct current transmission systems. Summary of the Invention

[0007] One of the objectives of this invention is to at least solve one or more of the aforementioned problems existing in the prior art. In other words, one of the objectives of this invention is to provide a method, system, electronic device, and computer-readable storage medium for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system that meets one or more of the aforementioned requirements.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system, comprising: Collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system; Based on steady-state operating parameters, a set of nonlinear control equations is constructed to characterize the AC / DC power conversion and coupling relationship on the inverter side; At the steady-state operating point of the system, a small perturbation is applied to the nonlinear control equations, and a linearized equation set characterizing the dynamic mapping relationship between various electrical state variables is established based on the response characteristics of the small perturbation. Obtain the feedback control loop on the inverter side, and combine the parameters of the feedback control loop to decouple the linearized equations into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller. By aggregating the constant matrix and the transfer function matrix, a transfer function admittance model is constructed. Apply a small disturbance signal to the transfer function admittance model and output a small disturbance stability evaluation index for the high voltage direct current transmission system.

[0009] In a preferred embodiment, the inverter-side nonlinear control equations include at least: The phase-locked loop control equation characterizing phase tracking characteristics, the constant DC voltage control equation characterizing voltage regulation characteristics, and the physical commutation equation characterizing AC / DC power conversion.

[0010] As a further preferred embodiment, the phase-locked loop control equation is used to establish a first mapping relationship between the phase-locked loop output phase angle and the q-axis component of the converter bus voltage; The DC voltage control equation is used to establish a second mapping relationship between the firing angle command value and the DC voltage error; The physical commutation equations are used to establish a third mapping relationship between the actual values ​​of the commutation bridge firing angle, commutation angle, and DC voltage, and the d-axis and q-axis components of the AC current.

[0011] As a preferred implementation, at the steady-state operating point of the system, a small perturbation is applied to the nonlinear control equations, the response characteristics of the small perturbation are extracted, and a linearized equation set characterizing the dynamic mapping relationship between various electrical state variables is established, specifically including: Determine the steady-state reference operating point of the current operating condition of the high-voltage direct current transmission system; Derive the local dynamic rate of change of each electrical state variable in the nonlinear control equation set with respect to a small disturbance at the steady-state reference operating point; Based on the local dynamic change rate, establish the linear transfer relationship between the incremental components of each electrical state variable, and integrate them to generate a linearized set of equations.

[0012] As a preferred implementation, the linearized equations are decoupled into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller, specifically including: Static parameters characterizing the inherent physical network on the inverter side in the isolated feedback control loop are used to construct a constant matrix representing the steady-state structure of the system. The dynamic parameters characterizing the regulator response in the feedback control loop are separated to construct the transfer function matrix.

[0013] As a preferred implementation, the transfer function admittance model is integrated into the external power grid system model to output a small-disturbance stability evaluation index for the high-voltage direct current transmission system, specifically including: Apply a small disturbance signal to the transfer function admittance model; Based on the transfer function admittance model, the time-domain dynamic response curves of each electrical state quantity after being subjected to a small disturbance signal are calculated and output. Based on the convergence characteristics of the time-domain dynamic response curve, the dynamic response state of the high-voltage direct current transmission system is evaluated, and a small-disturbance stability evaluation index is generated.

[0014] On the other hand, the present invention also provides a small-disturbance stability assessment system for a high-voltage direct current transmission inverter-side receiving-end system, comprising: The data acquisition module is used to collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system; The equation construction module is used to construct a set of nonlinear control equations characterizing the AC / DC power conversion and coupling relationship on the inverter side based on steady-state operating parameters; The feature extraction module is used to apply a small perturbation to the nonlinear control equations at the steady-state operating point of the system, and to establish a linearized equation set that characterizes the dynamic mapping relationship between various electrical state variables based on the response characteristics of the small perturbation. The matrix decoupling module is used to obtain the feedback control loop on the inverter side. Combining the parameters of the feedback control loop, the linearized equation system is decoupled into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller. The joint evaluation module is used to aggregate the constant matrix and the transfer function matrix to construct the transfer function admittance model; it is also used to apply small disturbance signals to the transfer function admittance model and output the small disturbance stability evaluation index of the high voltage direct current transmission system.

[0015] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the small-disturbance stability assessment method of the high-voltage direct current transmission inverter receiving-end system as described above.

[0016] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements a small-disturbance stability assessment method for a high-voltage direct current transmission inverter-side receiving-end system as described above.

[0017] Compared with existing technologies, the small-disturbance stability assessment method, system, electronic equipment, and computer-readable storage medium of the high-voltage direct current transmission inverter-side receiving-end system provided by this invention have the following advantages: This invention establishes a linearized equation set by extracting the small disturbance response characteristics of the nonlinear control equation set at the system's steady-state operating point. This linearized equation set is then specifically decoupled into a constant matrix representing the system's steady-state structure and a transfer function matrix representing the controller's dynamic response characteristics. This achieves a precise mathematical separation between the inherent static properties of the inverter's physical network and the dynamic control properties of the regulator. This structural separation allows the invention to directly aggregate the constant matrix and the transfer function matrix to construct a transfer function admittance model, effectively avoiding the massive computational load and complex solution process caused by the deep coupling of the physical network and control system in traditional electromagnetic transient modeling. Finally, the evaluation method using this transfer function admittance model can be seamlessly integrated into external power grid system models. While fully preserving the system's dynamic response characteristics, it significantly reduces the model's computational dimensionality, greatly improving the computational efficiency and applicability of small-disturbance stability assessment for high-voltage direct current transmission systems. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to an embodiment of the present invention; Figure 2 This is the feedback control loop of the high-voltage direct current transmission receiving-end system in this embodiment of the invention; Figure 3 This is a system topology diagram of the CIGRE DC standard test system according to an embodiment of the present invention; Figure 4 This is a comparison of the time-domain dynamic response curves of the small-disturbance stability assessment and verification methods of the high-voltage direct current transmission inverter-side receiving-end system according to an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of the invention. Various processes or components may be appropriately omitted, substituted, or added to the various examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0021] Embodiments of the present invention provide a method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps: S100: Collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system.

[0022] To establish a mathematical description of the receiving-end system suitable for small-disturbance stability assessment, steady-state operating parameters and physical structure parameters of the converter bus and inverter-side control loops are first collected.

[0023] In this embodiment, the steady-state operating parameters may include at least the actual phase angle θ of the converter bus voltage and the d-axis component of the converter bus voltage. and q-axis components Actual value of DC voltage DC voltage reference value Actual value of DC current d-axis component of the current flowing through the converter bus and q-axis components .

[0024] Meanwhile, the physical structural parameters can at least include the converter transformer turns ratio. commutation reactor Phase voltage amplitude of converter bus Number of cascaded converter bridges The parameters of the phase-locked loop and the constant DC voltage control loop are used as the basis for subsequently constructing the nonlinear control equation set and performing linearization processing.

[0025] It is understandable that the steady-state operating parameters collected in this step are not used in isolation, but are used to determine the steady-state reference operating point corresponding to the current operating condition, so that the subsequent nonlinear control equations, linearized equations and transfer function admittance models are all developed around the same receiving-end system operating state.

[0026] S200. Based on steady-state operating parameters, a set of nonlinear control equations is constructed to characterize the AC / DC power conversion and coupling relationship on the inverter side.

[0027] In one specific embodiment of the present invention, the nonlinear control equation set includes at least a phase-locked loop control equation characterizing phase tracking characteristics, a constant DC voltage control equation characterizing voltage regulation characteristics, and a physical commutation equation characterizing AC / DC power conversion.

[0028] As a feasible example, the phase-locked loop control equations are set as follows: ; in, s For the Laplace operator; PI PLL ( s )= K PLLP + K PLLI / s It is the phase-locked loop transfer function. K PLLP , K PLLI These are the proportional coefficient and integral coefficient of the phase-locked loop, respectively.

[0029] The constant DC voltage control equation is set as follows: ; in, PI CV ( s )= K CVP + K CVI / s It is the transfer function of the constant DC voltage control loop. K CVP , K CVI These are the proportional coefficient and integral coefficient of the constant DC voltage control loop, respectively. f v ( s )= K v / ( T v s +1) is the DC voltage measurement stage. K v , T v These are the measurement link coefficient and the measurement link time constant, respectively.

[0030] The physical commutation equations specifically include: firing angle equation: ; Phase angle equation: ; DC voltage equation: ; Equations for the d-axis and q-axis components of alternating current: ; in, θ , θ pll These represent the actual phase angle of the converter bus voltage and the phase angle of the phase-locked loop output, respectively. α ord Indicates the trigger angle command value; α This is the actual value of the firing angle input to the inverter bridge; U dc,ref This is a reference value for DC voltage. U dc This is the actual value of the DC voltage; I dc This is the actual value of the DC current; U d , U q These are the converter bus voltages. d , q Axial components; I d , I q These are the currents flowing through the converter bus, respectively. d , q Axial components; T i For converter transformer turns ratio; X i For commutation reactance; μ To change the phase angle; U This refers to the phase voltage amplitude at the converter bus. N B =2 represents the number of converter bridges cascaded.

[0031] Considering the numerous control components and highly coupled physical processes on the inverter side of high-voltage direct current transmission, a rigorous mathematical mapping of the phase-locked loop, constant DC control, and converter valve response at the underlying level helps prevent model distortion caused by the omission of a single control feature and improves the source-end reliability of the overall model.

[0032] S300. At the steady-state operating point of the system, a small disturbance is applied to the nonlinear control equation set, and a linearized equation set characterizing the dynamic mapping relationship between various electrical state variables is established based on the response characteristics of the small disturbance.

[0033] Please see Figure 2 , Figure 2 The feedback control loop of the high-voltage direct current transmission receiving-end system of this embodiment is shown.

[0034] In this embodiment, a set of control equations is established for the inverter-side receiver system around the feedback control loop, linearized, and based on this, an admittance model that can be used for small-disturbance stability assessment is obtained.

[0035] In one specific embodiment of this application, step S300 may include the following sub-steps: S301. Determine the steady-state reference operating point corresponding to the current operating condition; S302. Derive the local dynamic change rate of each electrical state variable in the nonlinear control equation set with respect to a small disturbance at the steady-state reference operating point. S303. Establish the linear transmission relationship between the incremental components of each electrical state variable based on the local dynamic change rate, thereby generating a linearized set of equations.

[0036] As a feasible example, the generated linearized system of equations can be represented as: ; ; ; ; ; ; Wherein, the subscript 0 represents the steady-state value of each physical quantity; γ 0= π - α 0- μ 0 represents the steady-state value of the turn-off angle; k 1. k 2. g 1. g 2. g 3. g 4 is an intermediate variable, and its expressions are as follows: ; ; ; ; ; ; Through the above steps, a set of linearized equations characterizing the dynamic mapping relationship of each electrical state variable can be obtained near the steady-state reference operating point. This transforms the nonlinear control process into an incremental relationship suitable for admittance modeling and stability assessment, thereby providing a unified mathematical basis for subsequent matrix decoupling and external power grid coupling analysis.

[0037] S400: Obtain the feedback control loop on the inverter side. Combine the parameters of the feedback control loop to decouple the linearized equations into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller.

[0038] In one specific embodiment of the present invention, decoupling the linearized equation system into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller specifically includes: Static parameters characterizing the inherent physical network on the inverter side in the isolated feedback control loop are used to construct a constant matrix representing the steady-state structure of the system. The dynamic parameters characterizing the regulator response in the feedback control loop are separated to construct the transfer function matrix.

[0039] As a feasible example, combined Figure 1 The feedback control loop shown extracts the static parameters characterizing the inherent physical network of the inverter side into a constant matrix. The parameters characterizing the dynamic response of the regulator are extracted as transfer function matrices. .

[0040] Specifically, constant matrix Represented as: ; The transfer function matrix is ​​represented as: .

[0041] By decoupling the linearized equations into a constant matrix and a transfer function matrix, the inherent physical static characteristics of the system and the frequency domain dynamic characteristics of the controller can be physically separated, thereby accurately characterizing the dynamic admittance characteristics of the AC / DC interface on the inverter side and providing a rigorous analytical model basis for small-disturbance stability analysis.

[0042] In addition, it should be noted that , , The auxiliary intermediate variables introduced for the subsequent construction of the admittance matrix are expressed as follows: ; ; .

[0043] S500. Aggregate the constant matrix and the transfer function matrix to construct the transfer function admittance model.

[0044] Specifically, aggregation can be achieved by superimposing and fusing the constant matrix and the transfer function matrix to establish a transfer function admittance model with the system input fluctuation vector as the excitation and the system output fluctuation vector as the response.

[0045] As an example, the transfer function admittance model can be represented by the following formula: .

[0046] The transfer function admittance model established in the above steps can serve as the model basis for small disturbance stability assessment, providing good data support for the analysis of small disturbance stability mechanism, while avoiding the use of complex electromagnetic transient modeling.

[0047] S600 applies a small disturbance signal to the transfer function admittance model and outputs a small disturbance stability evaluation index for the high voltage direct current transmission system.

[0048] In a specific embodiment of the present invention, step S600 may include the following sub-steps: S601. Apply a small disturbance signal to the transfer function admittance model; S602. Based on the transfer function admittance model, calculate and output the time-domain dynamic response curves of each electrical state quantity after being subjected to a small disturbance signal. S603. Based on the convergence characteristics of the time-domain dynamic response curve, evaluate the dynamic response state of the high-voltage direct current transmission system and generate small-disturbance stability evaluation index.

[0049] By injecting time-domain step disturbances into the transfer function admittance model and tracing the transient recovery trajectory of multidimensional electrical state quantities, it is beneficial to intuitively and accurately reflect the time-series dynamic characteristics of the receiving-end system on the inverter side of high-voltage direct current transmission under actual grid fluctuations, providing grid operation and dispatch personnel with a visualized basis for stability judgment.

[0050] Specifically, the short-circuit ratio parameters of the external power grid system model can be configured, and a step change signal can be applied to the DC voltage control reference value of the inverter side as a small disturbance signal at a preset simulation time node. Then, the overshoot and steady-state recovery time of the time-domain dynamic response curve after fluctuation caused by the small disturbance signal can be extracted.

[0051] As a feasible example, please refer to Figure 3 , Figure 3 A system topology diagram of a CIGRE DC standard test system is shown. Based on this system, the short-circuit ratio for small disturbances can be set to 5.613, and the constant DC voltage control reference value can be set at 3 seconds. It decreased from 1.0 pu to 0.95 pu, and then recovered to 1.0 pu at 3.5 seconds.

[0052] The final output time-domain dynamic response curve is as follows: Figure 4 As shown in the SSM section.

[0053] To verify the effectiveness of the above-mentioned small-disturbance stability assessment method, a verification example of this invention also employs a method based on... Figure 3 The CIGRE DC standard test system shown was used for simulation verification.

[0054] Specifically, in the construction and... Figure 3 The electromagnetic transient model corresponding to the CIGRE DC standard test system shown is injected with the same simulation disturbance, i.e., the short-circuit ratio is set to 5.613, and the constant DC voltage control reference value is changed at the 3s. It decreased from 1.0 pu to 0.95 pu, and then recovered to 1.0 pu at 3.5 seconds.

[0055] During this disturbance, the time-domain variation curve of the electromagnetic transient model is as follows: Figure 4 The EMT section is shown below. Depend on Figure 4 A comparison of the EMT and SSM sections shows that the method of this invention maintains good consistency with the comparative method in the dynamic response of the aforementioned variables. This indicates that the evaluation based on the transfer function admittance model of this invention can better reflect the dynamic response process of the receiving-end system on the inverter side of HVDC transmission. Furthermore, the method of this invention outputs corresponding small-disturbance stability evaluation indices, which can be used to improve the efficiency of stability analysis of HVDC transmission systems.

[0056] Another embodiment of the present invention provides a small-disturbance stability assessment system for a high-voltage direct current transmission inverter-side receiving-end system, which may specifically include: The data acquisition module is used to collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system; The equation construction module is used to construct a set of nonlinear control equations characterizing the AC / DC power conversion and coupling relationship on the inverter side based on steady-state operating parameters; The feature extraction module is used to apply a small perturbation to the nonlinear control equations at the steady-state operating point of the system, and to establish a linearized equation set that characterizes the dynamic mapping relationship between various electrical state variables based on the response characteristics of the small perturbation. The matrix decoupling module is used to obtain the feedback control loop on the inverter side. Combining the parameters of the feedback control loop, the linearized equation system is decoupled into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller. The joint evaluation module is used to aggregate the constant matrix and the transfer function matrix to construct the transfer function admittance model; it is also used to apply small disturbance signals to the transfer function admittance model and output the small disturbance stability evaluation index of the high voltage direct current transmission system.

[0057] In this system, the modules perform actions using the steps in the small-disturbance stability assessment method for the high-voltage direct current transmission inverter-side receiving-end system as described in the above embodiment.

[0058] This invention also provides an electronic device, which may include, but is not limited to, a processor 101, a memory 102, and optional communication interfaces 103 and input / output interfaces 104.

[0059] The processor can be a central processing unit (CPU), a digital signal processor (DSP), a programmable logic device (FPGA), an application-specific integrated circuit (ASIC), or other processing core capable of executing instructions. In this embodiment, the processor 101 is the control center of the electronic device, responsible for running the computer program stored in the memory 102 to execute one or more steps in the small-disturbance stability assessment method for a high-voltage direct current transmission inverter-side receiving-end system according to the above embodiment.

[0060] Memory can be any type of volatile or non-volatile storage medium, such as random access memory (RAM), read-only memory (ROM), flash memory, hard disk drive (HDD), solid-state drive (SSD), etc. Memory is used to store operating systems, various data, and computer programs.

[0061] A computer program stored in memory, whose instructions are executed by a processor, causes an electronic device to perform a small-disturbance stability assessment method for a high-voltage direct current transmission inverter-side receiving-end system according to the above embodiments.

[0062] This invention also provides a computer-readable storage medium on which a computer program is stored.

[0063] The computer program contains a series of instructions that, when loaded and executed by the processor of an electronic device, enable the electronic device to implement a small-disturbance stability assessment method for a high-voltage direct current transmission inverter-side receiving-end system as described in the above embodiments.

[0064] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0065] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of other embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This invention is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system, characterized in that, include: Collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system; Based on the aforementioned steady-state operating parameters, a set of nonlinear control equations characterizing the AC / DC power conversion and coupling relationship on the inverter side is constructed. At the steady-state operating point of the system, a small perturbation is applied to the nonlinear control equation set, and a linearized equation set characterizing the dynamic mapping relationship between various electrical state quantities is established based on the response characteristics of the small perturbation. Obtain the feedback control loop on the inverter side, and decouple the linearized equations into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller, based on the parameters of the feedback control loop. The constant matrix and the transfer function matrix are aggregated to construct a transfer function admittance model; A small disturbance signal is applied to the transfer function admittance model to output a small disturbance stability evaluation index for the high voltage direct current transmission system.

2. The method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to claim 1, characterized in that, The inverter-side nonlinear control equations include at least: The phase-locked loop control equation characterizing phase tracking characteristics, the constant DC voltage control equation characterizing voltage regulation characteristics, and the physical commutation equation characterizing AC / DC power conversion.

3. The method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to claim 2, characterized in that, The phase-locked loop control equations are used to establish the first mapping relationship between the phase-locked loop output phase angle and the q-axis component of the converter bus voltage; The constant DC voltage control equation is used to establish a second mapping relationship between the firing angle command value and the DC voltage error; The physical commutation equations are used to establish a third mapping relationship between the actual values ​​of the commutation bridge firing angle, commutation angle, and DC voltage, and the d-axis and q-axis components of the AC current.

4. The method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to claim 1, characterized in that, At the steady-state operating point of the system, a small perturbation is applied to the nonlinear control equations, the response characteristics of the small perturbation are extracted, and a linearized equation set characterizing the dynamic mapping relationship between various electrical state variables is established, specifically including: Determine the steady-state reference operating point of the current operating condition of the high-voltage direct current transmission system; The local dynamic rate of change of each electrical state variable in the nonlinear control equation set with respect to a small disturbance at the steady-state reference operating point is derived. Based on the local dynamic change rate, establish the linear transfer relationship between the incremental components of each electrical state variable, and integrate them to generate the linearized equation set.

5. The method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to claim 1, characterized in that, The linearized equations are decoupled into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller, specifically including: The static parameters characterizing the inherent physical network on the inverter side in the feedback control loop are separated to construct a constant matrix representing the steady-state structure of the system; The dynamic parameters characterizing the regulator response in the feedback control loop are separated to construct the transfer function matrix.

6. The method for evaluating the small-disturbance stability of a high-voltage direct current transmission inverter-side receiving-end system according to claim 1, characterized in that, By integrating the transfer function admittance model into an external power grid system model, the small-disturbance stability evaluation index of the high-voltage direct current transmission system is output, specifically including: A small disturbance signal is applied to the transfer function admittance model; Based on the transfer function admittance model, the time-domain dynamic response curves of each electrical state quantity after being subjected to the small disturbance signal are calculated and output. Based on the convergence characteristics of the time-domain dynamic response curve, the dynamic response state of the high-voltage direct current transmission system is evaluated, and the small-disturbance stability evaluation index is generated.

7. A small-disturbance stability assessment system for a high-voltage direct current transmission inverter-side receiving-end system, characterized in that, include: The data acquisition module is used to collect steady-state operating parameters of the converter bus in the high-voltage direct current transmission system; The equation construction module is used to construct a set of nonlinear control equations characterizing the AC / DC power conversion and coupling relationship on the inverter side based on the steady-state operating parameters. The feature extraction module is used to apply a small perturbation to the nonlinear control equation set at the steady-state operating point of the system, and establish a linearized equation set that characterizes the dynamic mapping relationship between various electrical state variables based on the response characteristics of the small perturbation. The matrix decoupling module is used to obtain the feedback control loop on the inverter side, and, in combination with the parameters of the feedback control loop, decouple the linearized equations into a constant matrix representing the steady-state structure of the system and a transfer function matrix representing the dynamic response characteristics of the controller. The joint evaluation module is used to aggregate the constant matrix and the transfer function matrix to construct a transfer function admittance model; it is also used to apply a small disturbance signal to the transfer function admittance model and output a small disturbance stability evaluation index of the high voltage direct current transmission system.

8. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the small-disturbance stability assessment method for the high-voltage direct current transmission inverter-side receiving-end system as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the small-disturbance stability assessment method for the high-voltage direct current transmission inverter-side receiving-end system as described in any one of claims 1 to 6.

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