Frequency-voltage coupling quantification method for high-voltage direct-current sending-end power system under large disturbance, storage medium and equipment

Abstract

The frequency-voltage coupling quantification method of high-voltage direct-current sending-end power system under large disturbance, storage medium and equipment belong to the technical field of power system. In order to solve the problem that there is no system-level quantification analysis method for the coupling degree of frequency and voltage under large disturbance condition. The electromagnetic transient simulation of high-voltage direct-current sending-end power system is carried out under disturbance condition, and the time-domain trajectories of system frequency, key node voltage and equipment state variables are obtained. The trajectories are divided to obtain multiple trajectory intervals. In each trajectory interval, the reference variable guided allowable window is used, and the representative snapshot point is selected based on the curvature criterion. Each trajectory interval obtains a snapshot point, and a coupling model is constructed at each snapshot point. By removing the cross coupling term in the Jacobian matrix of the alternating current network, the corresponding decoupling model is derived, and the quantification indexes of the structure level, the modal level and the response level are proposed to realize the quantification of the coupling degree.

Description

Technical Field

[0001] This invention belongs to the field of power system technology, and specifically relates to a frequency-voltage coupling quantization method, storage medium and device for a high voltage DC sending-end power system. Background Technology

[0002] As the scale of high-voltage direct current (HVDC) transmission continues to expand, the proportion of traditional synchronous generators in the sending-end power grid is declining, significantly weakening the system's inertia and voltage support capabilities. Simultaneously, the concentrated transmission of large-scale renewable energy through HVDC transmission channels results in complex characteristics of deep dynamic coupling between frequency and voltage in the sending-end system under large disturbances. To accurately quantify the degree of frequency-voltage coupling in the sending-end power grid under large disturbances and reveal its interaction mechanism, proposing a reasonable and effective frequency-voltage coupling quantification method is currently an important approach to solving the challenges of stability assessment in new power systems.

[0003] Currently, there are various analysis and evaluation schemes for describing the complex characteristics of frequency and voltage dynamics in high-voltage direct current (HVDC) sending-end systems under large disturbances, such as:

[0004] Wang Yunling et al. proposed "A Method for Evaluating the Ultimate DC Capacity of Sending-End Power Grids," Electric Power Construction, 2021, 42(11): 82-89. This article takes DC blocking faults as an example, constructs an analytical expression between transient frequency indicators and DC blocking quantities, and proposes a method for evaluating the ultimate DC feed-out capacity of single-circuit power grids that takes into account frequency stability constraints, effectively quantifying the ultimate DC feed-out capacity of sending-end power grids. However, this method only evaluates the ultimate DC feed-out capacity that the sending-end power grid can bear from a frequency perspective.

[0005] The article "Evaluation Index of Transient Overvoltage in HVDC Sending-End AC System Faults" proposed by Liu Xiaolin et al., Electric Power Construction, 2023, 44 (01): 64-72, analyzes the mechanism of transient overvoltage in AC systems and derives a transient overvoltage calculation method based on reactive power compensation and short-circuit ratio. It defines the transient voltage evaluation index R based on the ratio of the system short-circuit ratio to the compensation capacitor and AC filter parameters. However, this method only focuses on transient overvoltages caused by DC blocking faults.

[0006] The article "Analysis of the Dynamic Coupling Mechanism of Transient Voltage-Frequency in High-Proportion New Energy Sending-End Systems under Commutation Failure" by Gao Shang et al., Electric Power Construction, 2026, 47 (03): 80-92, addresses the new problem of unclear transient voltage and system frequency operation risks faced by high-proportion new energy sending-end systems after commutation failure. It studies the impact of new energy fault ride-through characteristics on the unbalanced power of the sending-end system and reveals the dynamic coupling law of transient voltage-frequency with transient voltage as the conduction path. However, this method only considers the coupling characteristics of the UHVDC transmission system itself and does not rise to the system level.

[0007] In summary, existing methods for analyzing the frequency and voltage characteristics of HVDC sending-end systems under large disturbances often treat frequency and voltage independently, paying little attention to the coupling effect between the two. The few studies that do focus on coupling characteristics are mostly specific to particular equipment, lacking a systematic analytical approach. Therefore, there is an urgent need for an analytical method for the frequency-voltage coupling characteristics of HVDC systems that considers the response characteristics of multiple devices. Summary of the Invention

[0008] This invention aims to address the current lack of a system-level quantitative analysis method for the coupling degree between frequency and voltage under conditions of large disturbances.

[0009] A frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances includes:

[0010] Electromagnetic transient simulations were performed on the high-voltage direct current (HVDC) power system under disturbance conditions to obtain the time-domain trajectories of system frequency, key node voltages, and state variables of each piece of equipment. The trajectories were segmented based on key segmented events to obtain multiple trajectory intervals. Within each trajectory interval, representative snapshot points were selected based on curvature criteria using an allowable window guided by reference variables. A snapshot point was obtained for each trajectory interval, and a locally linearized model considering frequency-voltage coupling, i.e., a coupled model, was constructed at each snapshot point. While maintaining the dynamic consistency of the equipment, the corresponding decoupling model was derived by removing cross-coupling terms from the Jacobian matrix of the AC network.

[0011] Based on coupling and decoupling models, quantitative indicators at the structural level are constructed by the strength of cross-coupling channels, quantitative indicators at the modal level are constructed by the influence of inherent dynamic characteristics, and quantitative indicators at the response level are constructed by the transient response under disturbance. The degree of coupling is quantified based on the quantitative indicators at the structural level and / or the quantitative indicators at the modal level and / or the quantitative indicators at the response level.

[0012] Furthermore, the process of selecting representative snapshot points based on the curvature criterion includes:

[0013] For the start time of two consecutive events and The k-th interval is defined to exclude transient responses near the event boundary to avoid the impact of event-triggered switching and control reinitialization; the allowable time window for snapshot points is defined. Divided into discrete grids, the candidate times for snapshot points are in the discrete grids. Considering the above, where n is the total number of candidate snapshot points within the interval and h is the selected sampling interval; by identifying local windows of multiple consecutive candidate points, the cumulative second time derivative of the reference trajectory is minimized, thus obtaining the snapshot instant. ,Right now:

[0014] ,

[0015] Where t represents time; To determine the n that minimizes the cumulative second time derivative of the reference trajectory; i represents the cumulative variable corresponding to multiple consecutive candidate points within the local window;

[0016] Based on snapshot Determine the snapshot point.

[0017] Furthermore, the allowed time windows for snapshot points are as follows:

[0018] ,

[0019] in, , The start and end times of the allowed time window; α and β are the proportions of the exclusion interval near the instant of the event. and It is the interval obtained by excluding the upper and lower limits of time. It provides a bounded time interval free from instantaneous event interference for snapshot selection; Indicates the duration of the segment.

[0020] Furthermore, within a local window, five consecutive candidate points are selected from multiple consecutive candidate points.

[0021] Furthermore, the process of constructing a locally linearized model considering frequency-voltage coupling at each snapshot point includes:

[0022] Linearizing the AC network power balance equation, we obtain the locally linearized model of frequency-voltage coupling represented by equation (3), with the injection interface being... Including the increase in active power and the increase in reactive power The injection interface is used to implement injection; the injection corresponding to the injection interface is incremental power.

[0023] (3)

[0024] in, It is the increment of the node phase angle. It is the increment of the node voltage. It is the increment of active power injected into the node. It is the increment of reactive power injected into the node; , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage; , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage; and This represents the change in active and reactive power after incremental power injection.

[0025] Furthermore, for synchronous generators, the incremental power injection of the synchronous generator is as follows:

[0026] (4)

[0027] Wherein, the coefficient matrix and Calculated under the conditions of this snapshot point; This represents the increase in the generator's active power. This represents the increase in reactive power of the generator. Synchronous generator voltage phase angle increment; This represents the rotor angular velocity increment. This refers to the internal status of the generator unit. This is the governor status increment; This represents the state increment of the excitation system; This is the state increment of the PSS system.

[0028] Furthermore, the process of deriving the corresponding decoupling model by removing cross-coupling terms from the Jacobian matrix of the communication network includes:

[0029] After obtaining the coupling model in formula (3), the network Jacobian matrix is ​​simplified in a targeted manner to obtain the decoupling model. .

[0030] Furthermore, the quantitative indicators at the structural level, modal level, and response level are as follows:

[0031] Quantitative indicators at the structural level , The directional structural coupling index from the V / Q channel to the P / θ channel is given by... ; The directional structural coupling index from the P / θ channel to the V / Q channel is given by... ;

[0032] Quantitative indicators at the modal level , and These represent the state matrices of the coupled and decoupled models at snapshot point k, respectively, with the corresponding eigenvalues ​​being... and ;

[0033] Quantitative indicators at the response level , and This represents the frequency and voltage response of the coupled model. , This indicates the corresponding decoupling response; It is the time-domain norm obtained on the response window T.

[0034] A computer storage medium storing at least one instruction, which is loaded and executed by a processor to implement the frequency-voltage coupling quantization method for a high-voltage DC power transmission system under large disturbances.

[0035] A frequency-voltage coupling quantization device for a high-voltage direct current (HVDC) power system under large disturbances, the device comprising a processor and a memory, wherein the memory stores at least one instruction, the at least one instruction being loaded and executed by the processor to implement the frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances as described in any one of claims 1 to 8.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] To address the significant enhancement of frequency-voltage coupling in modern power systems under large disturbances, this invention proposes a frequency-voltage coupling analysis method based on trajectory linearization and event segmentation modeling, and constructs a multi-level coupling quantification index system. This method, based on electromagnetic transient simulation, segments the response trajectory according to key events to establish a frequency-voltage coupling and decoupling model of the system. Combined with the proposed structural, modal, and response layer quantification indices, it can effectively characterize the degree of coupling at different stages of the system under large disturbances. This method can provide technical support for the analysis and control of modern power systems. Attached Figure Description

[0038] Figure 1 This is an overall flowchart of the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the allowable time window and snapshot point selection for segmenting large disturbance curves according to the present invention.

[0040] Figure 3 This is a schematic diagram of linearization modeling of transient trajectories under large disturbances, taking control switching caused by low voltage ride-through as an example, according to the present invention. Detailed Implementation

[0041] This invention proposes a frequency-voltage coupling quantification method for high-voltage direct current (HVDC) power systems under large disturbances. Based on electromagnetic transient simulation, the method segments the response trajectory according to key events, establishes a frequency-voltage coupling and decoupling model of the system, and combines the proposed structural, modal, and response layer quantification indices to effectively characterize the coupling degree of the system at different stages under large disturbances. This method can provide technical support for the analysis and control of novel power systems.

[0042] The frequency-voltage coupling quantization process of this invention is as follows: S1. Electromagnetic transient simulation is performed on the high-voltage DC power transmission system under typical disturbance conditions to obtain the time-domain trajectories of system frequency, key node voltages, and state variables of each piece of equipment; S2. Key segmented events are detected, and the trajectories are segmented accordingly; within each interval, representative snapshot points are selected based on the curvature criterion using an allowable window guided by reference variables; S3. A locally linearized model considering frequency-voltage coupling is constructed at each snapshot point, and while maintaining the dynamic consistency of the equipment, the corresponding decoupling model is derived by removing cross-coupling terms in the Jacobian matrix of the AC network; S4. Based on the coupling and decoupling models and the proposed three-layer quantization indices of structure, mode, and response, the degree of coupling is quantified; among which, the structural and modal indices characterize the inherent coupling mechanism, and the response layer indices verify the correctness of the former two through actual large disturbance responses. The invention will be described in detail below with reference to specific embodiments.

[0043] Specific implementation method one: Combining Figure 1 This implementation method is described below.

[0044] The frequency-voltage coupling quantization method based on a high-voltage direct current (HVDC) power system under large disturbances described in this embodiment includes:

[0045] S1. Perform electromagnetic transient simulation on the high-voltage DC power transmission system under typical disturbance conditions to obtain the time-domain trajectories of system frequency, key node voltage, and state variables of each piece of equipment.

[0046] Typical disturbance conditions include AC faults, load changes, generator failures and tripping, and DC faults; the state variables of each piece of equipment include at least the active power, reactive power, grid connection point voltage, control nonlinearity flags, and related mechanical dynamic variables of new energy sources, electrochemical energy storage, thermal power, and loads.

[0047] S2. Detect key segmentation events and segment the trajectory based on the key segmentation events to obtain multiple trajectory intervals; within each trajectory interval, select representative snapshot points based on the curvature criterion using an allowable window guided by reference variables.

[0048] During electromagnetic transient simulation, reference state variables are selected based on key events that cause changes in system structure or control configuration, such as control mode switching, saturation and dead-zone effects, network topology changes, and different fault stages. Based on reference state variables The corresponding trajectory curves can divide the trajectory under typical disturbances into several continuous intervals, as shown in the attached figure. Figure 2 As shown, the system operating configuration remains unchanged within each interval and rapid fluctuations near event boundaries must be avoided to ensure local smoothness of state evolution.

[0049] Different fault phases include entering low-voltage (or high-voltage) ride-through, exiting low-voltage (or high-voltage) ride-through, and returning to steady state, etc. Figure 3 Taking the low-pressure crossing as an example, entering the low-pressure crossing, exiting the low-pressure crossing, and returning to steady state are the key segment events, which divide the trajectory into four stages. (Refer to state variables.) It can be determined according to actual needs, such as the dq-axis current of a new energy generator during high and low voltage ride-through or frequency response operation, or the power when the synchronous generator governor is activated, etc. (e.g.) Figure 3 (As shown).

[0050] For the start time of two consecutive events and The k-th interval is defined to exclude transient responses near the event boundary to avoid the impact of event-triggered switching and control reinitialization. Let... The allowed time window for a snapshot point is defined as the duration of the segment.

[0051] (1)

[0052] in, , To allow for the start and end times of the time window; and α represents the start and end times of the k-th interval, and α and β represent the proportions of the excluded intervals near the instant of the event. and It is the interval obtained by excluding the upper and lower limits of time. It provides a bounded time interval free from instantaneous event interference for snapshot selection.

[0053] Within the allowed time window Internally, based on reference state variables Local smoothness determines the snapshot point time:

[0054] Allow time windows Divided into discrete grids, the candidate times for snapshot points are in the discrete grids. Considering the above, where n is the total number of candidate snapshot points within the interval, and h is the selected sampling interval, the snapshot instant is obtained by identifying local windows of multiple consecutive candidate points to minimize the cumulative second-order time derivative of the reference trajectory. ,Right now:

[0055] (2)

[0056] Where t represents time; To determine the value of n that minimizes the cumulative second-order time derivative of the reference trajectory; where i is the cumulative variable, five consecutive candidate points are selected for calculation in practice, meaning the value of i ranges from -2 to 2. At this point, we have... .

[0057] The selected snapshot point corresponds to the midpoint of the window containing the minimum curvature in the transient trajectory. To improve the robustness of numerical computation and reduce computational overhead, the reference state variable needs to be slightly smoothed before calculating the derivative.

[0058] S3. A snapshot point is obtained for each trajectory interval. A locally linearized model considering frequency-voltage coupling is constructed at each snapshot point. While maintaining the dynamic consistency of the equipment, the corresponding decoupling model is derived by removing the cross-coupling terms in the Jacobian matrix of the AC network. The specific process includes:

[0059] To derive the locally linearized model of frequency-voltage coupling at snapshot points, Figure 3 Taking snapshot point 2 as an example (it should be noted that, in fact...) Figure 2 The processing method for other snapshot points is the same. By extending the steady-state Jacobian formula, the AC network power balance equation is linearized at snapshot point 2, resulting in the local linearized model of frequency-voltage coupling represented by equation (3), with the injection interface being... Including the increase in active power and the increase in reactive power The injection interface is used to inject power into formula (3). The injection interface corresponds to the incremental power of synchronous generators, new energy power generation systems and other equipment.

[0060] The locally linearized model of frequency-voltage coupling, i.e., the coupling model, is as follows:

[0061] (3)

[0062] in, It is the increment of the node phase angle. It is the increment of the node voltage. It is the increment of active power injected into the node. It is the increment of reactive power injected into the node. , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage; , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage. and This represents the change in active and reactive power after incremental power injection.

[0063] Taking a synchronous generator as an example, the incremental power injection is based on formula (3). At a snapshot point, the synchronous generator operates in a fixed control mode during the corresponding stage. The incremental active and reactive power injection of the synchronous generator is linearized based on the transient operating conditions and can be expressed as a linear mapping between the generator state and the network algebraic variables. Specifically, the incremental power injection of the synchronous generator can be simplified as follows:

[0064] (4)

[0065] Wherein, the coefficient matrix and Calculate under the conditions of this snapshot point. This represents the increase in the generator's active power. This represents the increase in reactive power of the generator. Synchronous generator voltage phase angle increment; This represents the rotor angular velocity increment. This refers to the internal state of the unit (such as the excitation system and electromechanical coupling state). This is the governor status increment; This represents the state increment of the excitation system; This is the state increment of the PSS system.

[0066] During injection, the equipment is controlled, for example, by linearizing the swing equations to control the mechanical characteristics of the synchronous generator:

[0067]

[0068] In the formula, M is the inertial constant and D is the damping coefficient.

[0069] Incremental mechanical power Response from the speed controller (by The impact determines the excitation system response. It affects the internal electromotive force of the generator and the injection of reactive power.

[0070] Similarly, the linearization process based on the snapshot point corresponding to formula (3) can be directly extended to other equipment in the sending-end system. For new energy generator sets, the linearization can be achieved by redefining the corresponding injection interface to represent controls such as low voltage ride-through and frequency support. Similarly, high-voltage DC systems, static loads, and induction motor loads can be linearized at the snapshot point.

[0071] After obtaining the coupling model in formula (3), the core operation of constructing the decoupling model lies in the targeted simplification of the network Jacobian matrix, as shown in formula (5), which transforms the original Jacobian matrix into a block diagonal matrix. That is, the two key off-diagonal blocks representing frequency-voltage coupling are explicitly removed or set to zero, and only the diagonal blocks are retained. and The decoupling model (local linearization model) is as follows:

[0072] (5)

[0073] In suppressing the above network cross-coupling terms ( and At the same time, it is necessary to ensure all other network characteristics ( , The dynamic behavior at the equipment level remains unchanged. This means that the differential equations and control loops of generators (including their governors and excitation systems), new energy units, high-voltage direct current transmission systems, and various loads are not modified in any way, thus ensuring that the decoupling model differs from the original coupled model only in whether or not frequency-voltage coupling is considered. After eliminating algebraic variables, the two models ultimately form an ideal comparison benchmark based on exactly the same snapshot operating conditions and system configuration, providing a basis for subsequent quantification of the frequency-voltage coupling strength under large disturbances.

[0074] S4. Based on the coupling model of formula (3) and the decoupling model of formula (5), three-layer quantification indicators of structure, mode and response are proposed to realize the quantification of coupling degree; among them, the structure and mode indicators represent the internal coupling mechanism, and the response layer indicators verify the correctness of the former two through actual large disturbance response.

[0075] Because coupling effects manifest at multiple levels, such as structural coupling of the system matrix, changes in intrinsic dynamic characteristics, and influences at the transient response level, a multi-level coupling quantization framework is adopted to comprehensively characterize these different levels of coupling properties. This framework encompasses quantification metrics at three levels: structural, modal, and response.

[0076] A. At the structural level, frequency-voltage coupling is quantified by the strength of the cross-coupling channels. To represent the directional structural coupling between the P / θ and V / Q channels, the equivalent sensitivity is obtained through Schur cancellation. The effective active power angular sensitivity is obtained by eliminating ΔQ and ΔP respectively. and reactive power voltage sensitivity :

[0077] (6)

[0078] Based on the above effective sensitivity, the directional structural coupling index from the V / Q channel to the P / θ channel is defined. Directional structural coupling index from P / θ channel to V / Q channel for:

[0079] (7)

[0080] Combining the two types of coupling channels, the overall structural layer quantitative index is defined as follows: .

[0081] B. At the modal level, frequency-voltage coupling is quantified by its impact on the inherent dynamic characteristics of the system, reflected in the modal characteristics of a snapshot-point-based locally linear model. This layer focuses on how coupling alters the dominant modes of control system dynamics, rather than the coupling path itself. At snapshot point k, let... and These represent the state matrices of the coupled and decoupled models, respectively; their corresponding eigenvalues ​​are... and The modal-level coupling quantization index is defined as follows:

[0082] (8)

[0083] Indicator η m Measure the relative deviation of the system modal characteristics caused by frequency-voltage coupling at a given snapshot point. A larger η m The value indicates that coupling significantly alters the original dynamic characteristics, such as modal frequencies or damping characteristics, while a smaller η value... m The value implies that the coupling has a limited impact on the underlying modal structure. This is achieved by calculating η between snapshots. m It can systematically characterize the evolution of coupling degree on large disturbance trajectories.

[0084] It should be noted that when performing frequency-voltage coupling quantization analysis on mode i of interest, the eigenvalues ​​corresponding to mode i of interest are used. and Quantitative indicators can be calculated.

[0085] C. At the response level, frequency-voltage coupling is quantified by its impact on the transient response under large disturbances. Unlike structural and modal level indices characterizing coupling channels and inherent dynamic properties, response level indices directly reflect how coupling affects the actual evolution of system frequency and voltage during disturbances. The coupled response corresponds to the complete electromagnetic transient simulation trajectory, while the decoupled response is obtained based on an equivalent model that ignores frequency-voltage cross-feedback. Let... and This represents the frequency and voltage response of the coupled model. , This represents the corresponding decoupling response. The response layer coupling index is defined as:

[0086] (9)

[0087] in, It is the time-domain norm obtained over a specific response window T. The index η rThe relative deviation between the coupling and decoupling transient responses caused by frequency-voltage coupling is measured. η r A larger value indicates that coupling has a significant impact on the system behavior under the corresponding perturbation, while η r The smaller the value, the less sensitive the transient response is to coupling effects.

[0088] The above three indicators are three levels of quantitative indicators used to characterize different aspects of capabilities. They are generally used together for frequency-voltage coupling quantitative analysis. However, it should be noted that one of the indicators can also be selected for frequency-voltage coupling quantitative analysis according to actual needs. Specific Implementation Method Two:

[0090] This embodiment is a computer storage medium that stores at least one instruction. The at least one instruction is loaded and executed by a processor to implement the frequency-voltage coupling quantization method for a high-voltage DC power transmission system under large disturbances.

[0091] It should be understood that the instructions include computer program products, software, or computerized methods corresponding to any method described in this invention; the instructions can be used to program computer systems or other electronic devices. Computer storage media may include readable media on which instructions are stored, and may include, but are not limited to, magnetic storage media, optical storage media; magneto-optical storage media include read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), and flash memory layers, or other types of media suitable for storing electronic instructions. Specific implementation method three:

[0093] This embodiment is a frequency-voltage coupling quantization device for a high-voltage direct current power system under large disturbances. The device includes a processor and a memory. It should be understood that it includes any device including a processor and a memory as described in this invention. The device may also include other units and modules that perform display, interaction, processing, control and other functions through signals or instructions.

[0094] The memory stores at least one instruction, which is loaded and executed by the processor to implement the frequency-voltage coupling quantization method for a high-voltage DC power system under large disturbances.

[0095] Those skilled in the art will understand that at least one stored instruction constitutes a computer program product corresponding to a method or system. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0096] This application is described with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of this application, and can also be used with corresponding devices. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0100] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0101] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances, characterized in that, include: Electromagnetic transient simulation of the high-voltage DC power transmission system under disturbance conditions is performed to obtain the time-domain trajectories of system frequency, key node voltage, and state variables of each piece of equipment. The trajectory is segmented based on key segmentation events to obtain multiple trajectory intervals; Within each trajectory interval, a representative snapshot point is selected based on the curvature criterion using an allowable window guided by a reference variable. A snapshot point is obtained for each trajectory interval, and a locally linearized model considering frequency-voltage coupling, i.e., a coupling model, is constructed at each snapshot point. While maintaining the dynamic consistency of the equipment, the corresponding decoupling model is derived by removing the cross-coupling terms in the Jacobian matrix of the AC network. Based on coupling and decoupling models, quantitative indicators at the structural level are constructed by the strength of cross-coupling channels, quantitative indicators at the modal level are constructed by the influence of inherent dynamic characteristics, and quantitative indicators at the response level are constructed by the transient response under disturbance. The degree of coupling is quantified based on the quantitative indicators at the structural level and / or the quantitative indicators at the modal level and / or the quantitative indicators at the response level.

2. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 1, characterized in that, The process of selecting representative snapshot points based on the curvature criterion includes: For the start time of two consecutive events and The k-th interval is defined to exclude transient responses near the event boundary to avoid the impact of event-triggered switching and control reinitialization; the allowable time window for snapshot points is defined. Divided into discrete grids, the candidate times for snapshot points are in the discrete grids. Considering the above, where n is the total number of candidate snapshot points within the interval and h is the selected sampling interval; by identifying local windows of multiple consecutive candidate points, the cumulative second time derivative of the reference trajectory is minimized, thus obtaining the snapshot instant. ,Right now: ， Where t represents time; To determine the n that minimizes the cumulative second time derivative of the reference trajectory; i represents the cumulative variable corresponding to multiple consecutive candidate points within the local window; Based on snapshot Determine the snapshot point.

3. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 1, characterized in that, The allowed time windows for snapshot points are as follows: ， in, , The start and end times of the allowed time window; α and β are the proportions of the exclusion interval near the instant of the event. and It is the interval obtained by excluding the upper and lower limits of time. It provides a bounded time interval free from instantaneous event interference for snapshot selection; Indicates the duration of the segment.

4. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 1, characterized in that, Select 5 consecutive candidate points within a local window.

5. A frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to any one of claims 1 to 4, characterized in that, The process of constructing a locally linearized model that takes into account frequency-voltage coupling at each snapshot point includes: Linearizing the AC network power balance equation, we obtain the locally linearized model of frequency-voltage coupling represented by equation (3), with the injection interface being... Including the increase in active power and the increase in reactive power The injection interface is used to implement injection; the injection corresponding to the injection interface is incremental power. （3） in, It is the increment of the node phase angle. It is the increment of the node voltage. It is the increment of active power injected into the node. It is the increment of reactive power injected into the node; , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage; , It is a Jacobian matrix, representing the partial derivatives of active and reactive power with respect to node voltage; and This represents the change in active and reactive power after incremental power injection.

6. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 5, characterized in that, For synchronous generators, the incremental power injection is as follows: （4） Wherein, the coefficient matrix and Calculated under the conditions of this snapshot point; This represents the increase in the generator's active power. This represents the increase in reactive power of the generator. Synchronous generator voltage phase angle increment; This represents the rotor angular velocity increment. This refers to the internal status of the generator unit. This is the governor status increment; This represents the state increment of the excitation system; This is the state increment of the PSS system.

7. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 5, characterized in that, The process of deriving the corresponding decoupling model by removing cross-coupling terms from the Jacobian matrix of the communication network includes: After obtaining the coupling model in formula (3), the network Jacobian matrix is ​​simplified in a targeted manner to obtain the decoupling model. .

8. The frequency-voltage coupling quantization method for a high-voltage direct current (HVDC) power system under large disturbances according to claim 7, characterized in that, The quantitative indicators at the structural level, modal level, and response level are as follows: Quantitative indicators at the structural level , The directional structural coupling index from the V / Q channel to the P / θ channel is denoted as , where ; The directional structural coupling index from the P / θ channel to the V / Q channel is given by... ; Quantitative indicators at the modal level , and These represent the state matrices of the coupled and decoupled models at snapshot point k, respectively, with the corresponding eigenvalues ​​being... and ; Quantitative indicators at the response level , and This represents the frequency and voltage response of the coupled model. , This represents the corresponding decoupling response; It is the time-domain norm obtained on the response window T.

9. A computer storage medium, characterized in that, The storage medium stores at least one instruction, which is loaded and executed by a processor to implement the frequency-voltage coupling quantization method for a high-voltage DC power transmission system under large disturbances as described in any one of claims 1 to 8.

10. A frequency-voltage coupling quantization device for a high-voltage direct current (HVDC) power system under large disturbances, characterized in that, The device includes a processor and a memory, the memory storing at least one instruction, which is loaded and executed by the processor to implement the frequency-voltage coupling quantization method for a high-voltage DC power transmission system under large disturbances as described in any one of claims 1 to 8.

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