A direct current voltage scale POD configuration method, device, equipment and medium

Abstract

The application belongs to the technical field of power system control, and specifically discloses a DC voltage scale POD configuration method, device, equipment and medium. The application establishes a motion equation model to lay a foundation for quantifying the dynamic influence of equipment. Based on the model, the damping torque method is used to extract the stabilizing torque coefficient for LCC-HVDC, directly evaluate the damping and synchronization contribution of network construction and network following equipment to the oscillation mode, and locate the weak link of stability. Then, the amplitude and phase sensitivity of these coefficients to the core control path of the equipment is calculated, and it is explicitly revealed that the system damping can be effectively enhanced by adjusting the characteristics of the active frequency path. Finally, based on the selected controller input and output positions, and using the sensitivity to guide the parameter design, the damping controller configuration has a targeted and quantitative basis, and the frequency response of the key path is reshaped, so as to compensate for the damping loss caused by the insufficient capacity of the network construction equipment without relying on communication, and improve the dynamic stability of the system.

Description

Technical Field

[0001] This application belongs to the field of power system control technology, specifically relating to a DC voltage scale POD configuration method, device, equipment, and medium. Background Technology

[0002] Currently, a large amount of renewable energy in resource-rich areas needs to be converted into alternating current (AC) via inverters and then transmitted to resource-scarce regions via high-voltage direct current (HVDC) transmission. When grid capacity is insufficient, the transmission system faces the problem of DC voltage time-scale oscillations dominated by HVDC transmission. By designing a DC voltage time-scale power oscillation damping (POD) controller, this oscillation can be suppressed, and the proportion of grid equipment upgrades can be minimized, resulting in economic benefits. Existing equipment damping controller design methods for DC voltage time-scale oscillations can be mainly divided into the following categories: The first category comprises local controller design methods for single-unit or multi-unit infinite power systems. In single-unit infinite power scenarios, this primarily addresses single-unit infinite power grid-connected systems or single-unit infinite power grid-connected systems, focusing on oscillation issues caused by strong or weak power grids. Specific methods include impedance reshaping and damped path analysis. In multi-unit infinite power systems, this mainly targets systems with multiple identical devices connected in parallel, using impedance reshaping to solve the problem of circulating currents between units. However, real-world systems consist of different devices and networks, making it difficult to simply equate them to infinite power systems. Therefore, controller design methods for infinite power systems are often unsuitable for power systems containing various different devices.

[0003] The second category is the design method for wide-area oscillation damping controllers that include multiple devices. This method typically uses the time-domain state-space method to analyze the participation factors of the dominant oscillation mode of the system, and uses the controllability and observability of the state variables to select the input and output positions of the damping controller to perform wide-area damping control of the system. This method relies on communication, which increases costs, and there are risks of communication delays, packet loss, or single points of failure, which reduces the reliability of the system.

[0004] The third category is the local controller design method for multi-machine systems. This method is mainly based on the negative damping path of a specific control loop and uses phase compensation methods to compensate for the phase of the negative damping path. This method cannot analyze the overall frequency response characteristics of the equipment required by the power system from power to internal potential, making it difficult to provide guidance for equipment suppliers.

[0005] Therefore, this paper proposes an effective local damping controller design method to address the time-scale oscillation of DC voltage in the power transmission system caused by insufficient grid coverage. This method is beneficial to the stable operation of the power system, provides design reference for equipment manufacturers, and saves grid operators the cost of upgrading grid equipment. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this application is to provide a DC voltage scale POD configuration method, apparatus, equipment and medium, which aims to solve the technical problem that the current means of suppressing power oscillations caused by insufficient grid equipment capacity are inconsistent with reality and limited by communication, resulting in poor power system stability.

[0007] The first aspect of this application relates to a DC voltage-scale POD configuration method, comprising: step S10, converting the input quantities of various types of equipment in a transmission system including grid-connected control stations into power parameters at internal potentials; and then converting the network port output quantities into port power parameters to establish a motion equation model for the equipment; wherein, the various types of equipment include grid-connected equipment, grid-connected equipment, and LCC-HVDC equipment; step S20, based on the damping torque method, obtaining the stabilizing damping torque coefficient and stabilizing synchronous torque coefficient of the grid-connected equipment and grid-connected equipment for the LCC-HVDC equipment through the motion equation model; step S30, obtaining the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and stabilizing synchronous torque coefficient with respect to the active frequency, active voltage, reactive frequency, and reactive voltage of the grid-connected equipment and grid-connected equipment; step S40, based on the amplitude sensitivity and phase sensitivity, combined with the input variables and output positions of the selected damping controller, obtaining the damping controller parameters to reshape the path frequency response characteristics of the equipment.

[0008] In one embodiment, step S10 includes: based on the principle of equivalent detection of equipment grid state, establishing small-signal offset equations for various types of equipment near the steady-state operating point, wherein the small-signal offset equations map the filter inductor current and terminal voltage of the equipment to the active power and reactive power at the internal potential; based on the principle of network power dynamic response, and combined with the small-signal offset equations as input, using the power solution expression, establishing the active power and reactive power response equations of the network at the port.

[0009] In one embodiment, step S20 includes: constructing a first device matrix representing the input-output relationship of various types of devices and a first network matrix representing the power coupling relationship of network nodes according to the motion equation model; based on the first device matrix and the first network matrix, obtaining a transfer function representing the damping characteristics of the system according to the damping torque method, as a first transfer model; extracting the real part and imaginary part of the first transfer model at the critical stability point of the dominant mode to obtain the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient.

[0010] In one embodiment, step S30 includes: constructing the amplitude partial derivative function and phase partial derivative function of the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient with respect to the device path function; and calculating the amplitude sensitivity and phase sensitivity corresponding to each device path based on the partial derivative function and the mapping relationship between the amplitude and phase of the device path.

[0011] In one embodiment, step S40 includes: step S41, determining the target device path to be reshaped based on the amplitude sensitivity and phase sensitivity of the device path; step S42, establishing a transfer function of the target device path after adding a damping controller, based on the selected input variables and output position, as a second transfer model, the second transfer model consisting of the original path transfer function, the transfer function from the output position to the internal potential control target, and the damping controller transfer function; step S43, establishing a mapping function relationship between the lead-lag phase and gain parameters of the damping controller and the amplitude and phase of the target device path at the dominant oscillation frequency; step S44, combining the adjustment direction indicated by the amplitude sensitivity and phase sensitivity, and based on the constraints on phase and amplitude changes during path reshaping, solving the mapping function relationship to obtain the damping controller parameter range that satisfies the constraints, and selecting parameters from it to reshape the frequency response characteristics of the device path.

[0012] In one embodiment, step S41 includes: determining whether the signs of the damping torque sensitivity and the synchronous torque sensitivity corresponding to the device path are consistent; if they are consistent, then the target device path to be reshaped is determined; if they are inconsistent, then determining whether the absolute value of the damping torque sensitivity is much greater than the synchronous torque sensitivity; if so, then the target device path to be reshaped is determined; otherwise, the next path is selected for judgment.

[0013] In one embodiment, before step S42, the method further includes: selecting input variables and outputs based on the approximate decoupling characteristics of the dq-axis of the current inner loop of the grid-connecting equipment and the generation of the inner loop's internal potential amplitude frequency; the input variable is selected as the active power or reactive power measured at the internal potential of the equipment; the output position is selected at the d-axis or q-axis voltage reference value output by the current inner loop, specifically: when reshaping the active frequency path, the input variable is selected as active power, and the output position is selected as the q-axis voltage reference value; when reshaping the active voltage path, the input variable is selected as active power, and the output position is selected as the d-axis voltage reference value; when reshaping the reactive frequency path, the input variable is selected as reactive power, and the output position is selected as the q-axis voltage reference value; when reshaping the reactive voltage path, the input variable is selected as reactive power, and the output position is selected as the d-axis voltage reference value.

[0014] The second aspect of this application relates to a DC voltage scale POD configuration device, comprising: a model building module, used to convert the input quantities of various types of equipment in a transmission system, including grid-connected control stations, into power parameters at internal potentials, and to convert the network port output quantities into port power parameters, so as to establish a motion equation model of the equipment; wherein, the various types of equipment include grid-connected equipment, grid-connected equipment, and LCC-HVDC equipment; a coefficient calculation module, used to obtain the stabilizing damping torque coefficient and stabilizing synchronous torque coefficient of grid-connected equipment and grid-connected equipment for LCC-HVDC equipment through the motion equation model based on the damping torque method; a sensitivity acquisition module, used to obtain the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and stabilizing synchronous torque coefficient with respect to the active frequency, active voltage, reactive frequency, and reactive voltage of grid-connected equipment and grid-connected equipment; and a reshaping control module, used to obtain damping controller parameters based on the amplitude sensitivity and phase sensitivity, combined with the input variables and output positions of the selected damping controller, to reshape the frequency response characteristics of the equipment path.

[0015] Thirdly, this application provides an electronic device, comprising: at least one memory for storing a program; and at least one processor for executing the program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any possible implementation thereof.

[0016] Fourthly, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0017] Fifthly, this application provides a computer program product that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0018] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0019] Overall, the technical solution proposed in this application effectively solves the problems of difficulty in suppressing power oscillations and poor system stability caused by insufficient network equipment capacity through a series of coherent and logically progressive technical means, and achieves the beneficial effect of enhanced stability that is more practical and independent of communication compared to existing technologies. First, step S10 transforms the input and output quantities of different types of devices into internal potential and power parameters at the ports, and establishes a universal motion equation model accordingly. This method lays the analytical foundation for accurately quantifying the impact of various devices on system dynamics within a unified framework.

[0020] Furthermore, based on this model, step S20 uses the damping torque method to extract the stabilizing torque coefficient for the LCC-HVDC equipment. This enables a direct and quantitative assessment of the damping and synchronization capabilities of the grid-connecting and grid-following equipment for specific oscillation modes, thereby accurately locating weak points in stability.

[0021] Based on this, step S30 further calculates the amplitude and phase sensitivity of these key coefficients relative to the four core control paths of the equipment. This method solves the problem that traditional methods have difficulty in identifying specific influencing paths, thus clearly revealing which path, such as the amplitude or phase of the active frequency path, can most effectively enhance system damping by adjusting which path.

[0022] Finally, step S40 selects the input and output positions of the controller based on the above analysis conclusions and the amplitude-frequency characteristics of the internal potential of the equipment, and uses the obtained sensitivity to guide the parameter design. This method makes the configuration of the damping controller have clear physical targeting and quantitative basis, and can directly reshape the frequency response of the equipment path that is most critical to stability. Thus, without relying on communication, it can locally and purposefully compensate for the damping deficiency caused by insufficient capacity of the grid equipment, and fundamentally improve the dynamic stability of the power system. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the DC voltage scale POD configuration method provided in the embodiments of this application; Figure 2 This is a schematic diagram of the LCC-HVDC transmission system provided in the embodiments of this application; Figure 3 This is a linearized block diagram of the motion equation model provided in the embodiments of this application; Figure 4 This is a flowchart illustrating step S40 provided in an embodiment of this application; Figure 5 This is a schematic diagram of the network equipment control structure and damping controller configuration provided in the embodiments of this application; Figure 6 This is a waveform comparison diagram of the linearized model and the original nonlinear model provided in the embodiments of this application; Figure 7 Here are schematic diagrams of parameter analysis for the damping controller of the network equipment provided in this application embodiment: (a) is a three-dimensional schematic diagram of parameter solution; (b) is a schematic diagram of the feasible region of parameter selection range; Figure 8 This is a schematic diagram of the reshaping of the amplitude-frequency characteristics of the active frequency path of the network-building device provided in the embodiments of this application; Figure 9The following are waveform diagrams before and after the operation of the equipment damping controller provided in the embodiments of this application: (a) is the output power waveform of the grid-connected equipment; (b) is the DC voltage waveform of the grid-connected equipment; (c) is the frequency waveform of the virtual synchro of the grid-connected equipment; (d) is the DC current waveform of the rectifier side of the conventional DC transmission. Figure 10 This is a structural block diagram of the DC voltage scale POD configuration device provided in the embodiments of this application; Figure 11 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0026] In this application, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0027] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0028] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0029] Currently, strategies for suppressing power oscillations caused by insufficient grid capacity are typically based on simplified models or idealized assumptions, leading to dynamic response characteristics that do not match the complex operating conditions of real power grids. Furthermore, many existing methods rely on fast and reliable inter-station communication for coordinated control, resulting in performance degradation during communication delays or interruptions. These shortcomings collectively lead to ineffective suppression measures, insufficient system damping, and poor stability. In addition, existing methods lack the ability to analyze the frequency response characteristics from the device port power to the amplitude and frequency of its internal potential from a system-wide perspective. Therefore, it is difficult to clearly reveal the contribution mechanisms and paths of various devices to system oscillations, and thus cannot provide clear guidance for equipment manufacturers on how to optimize their controller designs to meet system requirements.

[0030] Based on this, this application proposes an embodiment of a DC voltage-scale POD configuration method. Please refer to... Figure 1 , Figure 1 This is a flowchart illustrating the DC voltage scale POD configuration method provided in the embodiments of this application.

[0031] In this embodiment, the method includes steps S10 to S40.

[0032] Step S10: Convert the input quantities of various types of equipment in the power transmission system, including the grid control station, into power parameters at the internal potential; then convert the output quantities of the network port into port power parameters to establish the motion equation model of the equipment.

[0033] It should be noted that the DC voltage time scale mentioned in this article mainly refers to the system dynamic response stage with a frequency of around 10Hz, dominated by dynamic components such as the DC-side capacitor of the converter station and the DC line inductance.

[0034] It's important to note that the core of this step lies in establishing a unified and accurate equation of motion model. Input quantities typically refer to commands or feedback signals applied to the device controller, such as frequency deviations and voltage deviations. Internal potential (EV) is the virtual source point in the internal control loop of the grid-connected / grid-connected equipment that generates the final voltage command. Transformation refers to quantifying the impact of these input quantities on the device's behavior into its effect on power parameters at the internal potential, such as virtual power or directly related electrical quantities, through the device's control block diagram and transfer function. Similarly, the electrical output quantities at the device's connection port to the grid, such as voltage and current, are transformed into port power parameters.

[0035] Understandably, this modeling process ensures that the model accurately reflects the complete dynamics of the equipment from control input to the grid interface, laying the foundation for subsequent analysis. Please refer to [reference needed]. Figure 2 , Figure 2This is a schematic diagram of the grid-following (GFL) power supply system provided in this application embodiment, which transmits power from the grid-forming (GFM) station via LCC-HVDC. The various types of equipment include grid-following (GFL) equipment, grid-forming (GFM) equipment, and the LCC-HVDC equipment on the right side of the diagram.

[0036] Understandably, grid-connected equipment refers to power generation or conversion equipment with the ability to independently establish and regulate voltage and frequency, such as virtual synchronous machines; grid-connected equipment refers to equipment whose output depends on the grid voltage and frequency as a synchronization reference, such as phase-locked loop-based converters; and LCC-HVDC equipment refers to traditional DC transmission systems based on thyristor commutation, whose operating characteristics are sensitive to the strength of the AC system.

[0037] Step S20: Based on the damping torque method, obtain the stabilizing damping torque coefficient and stabilizing synchronization torque coefficient of the grid-connecting equipment and the grid-building equipment for the LCC-HVDC equipment through the motion equation model.

[0038] Understandably, the damping torque method is a classic system dynamics analysis theory that decomposes the influence of equipment on system oscillation modes into two parts: damping torque and synchronization torque. This step, using the motion equation model established in step S10, calculates the stabilizing damping torque coefficient and stabilizing synchronization torque coefficient generated by the grid-connected and grid-connecting equipment on the operating state of the LCC-HVDC equipment. These two coefficients quantify the former's contribution to the latter's stability (damping and synchronization capability); a positive damping torque coefficient indicates the provision of positive damping, which is beneficial to system stability.

[0039] Step S30: Obtain the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient for the four paths of active frequency, active voltage, reactive frequency and reactive voltage of the grid-connecting equipment and the grid-connecting equipment.

[0040] Understandably, sensitivity analysis is performed in this step to gain a deeper understanding of and optimize the aforementioned stability contribution. Network-connecting / grid-following devices typically respond to system changes and output power through four independent paths of their controllers: active-frequency path, active-voltage path, reactive-frequency path, and reactive-voltage path. Amplitude sensitivity refers to the rate of change of gain in these four paths with respect to the two coefficients described in step S20, used to identify the control path with the most significant impact. Phase sensitivity refers to the rate of change of phase in these paths with respect to the coefficients, used to determine the critical phase compensation relationship required to provide positive damping. Obtaining these sensitivities forms the basis for subsequent targeted design of damping controllers.

[0041] Step S40: Based on the amplitude sensitivity and phase sensitivity, and combined with the selected input variables and output positions of the damping controller, obtain the damping controller parameters to reshape the device path frequency response characteristics.

[0042] Understandably, this step is the final synthesis stage of controller design. Based on the amplitude and phase sensitivity obtained in step S30, it can be determined which control path(s) should be prioritized for injecting the damping signal, and the phase that needs to be compensated on that path. The input variables of the damping controller selected in conjunction with the actual engineering situation are usually locally measurable signals that reflect the oscillation mode, such as line power, bus frequency, and DC voltage. The output position, i.e., which control path the damping signal is injected into, can be calculated using classical control theory or optimization algorithms. This typically involves specific parameters of the damping controller, such as gain and time constant, from a lead-lag compensation stage with DC blocking. The ultimate effect is to reshape the frequency response characteristics of the equipment path, that is, to adjust the amplitude and phase frequency characteristics of the target control path to provide maximum positive damping near the critical oscillation frequency.

[0043] In this embodiment, by establishing a complete motion equation model from control input to the power grid port and using damping torque analysis, this method can more accurately reflect the dynamic interaction of equipment in the real system, overcome the defects of simplified models not matching reality, and make the stability analysis results more valuable for engineering guidance.

[0044] In this embodiment, by quantitatively analyzing the sensitivity of each control path and the targeted reshaping of the frequency response, the configured DC voltage scale POD can provide precise and effective positive damping for the system, especially for LCC-HVDC equipment, effectively suppressing power oscillations and thus significantly improving the stability of the power system.

[0045] In this embodiment, the POD configuration mainly utilizes local signals, such as active power, as input. Essentially, it is a local control strategy that does not rely on fast inter-station communication, thus solving the problem of communication limitations and improving control reliability.

[0046] In this embodiment, the frequency response characteristics of the overall equipment required by the power system, from power to internal potential, can be systematically analyzed, clearly revealing the contribution and mechanism of each device and control path to system damping. This enables equipment suppliers to optimize the controller design of their products (grid-connecting / connecting equipment) based on this guidance, preset or adjust the characteristics of relevant control paths, so that they can naturally provide better stability support when connected to the system, realizing positive guidance from system requirements to equipment design.

[0047] Furthermore, this application provides feasible decomposition steps for each of the above steps.

[0048] In this embodiment, step S10 includes: based on the principle of equivalent detection of equipment grid state, establishing small-signal offset equations for various types of equipment near the steady-state operating point, the small-signal offset equations mapping the filter inductor current and terminal voltage of the equipment to the active power and reactive power at the internal potential; based on the principle of network power dynamic response, combined with the small-signal offset equations as input, and using the power solution expression, establishing the active power and reactive power response equations of the network at the port.

[0049] Understandably, this section elaborates on the specific implementation of converting input quantities into power parameters at the internal potential and output quantities into port power parameters. Step S10 is the core modeling step that forms the basis of the entire method analysis. Its purpose is to establish a mathematical model that can accurately describe the relationship between the internal dynamics of the device and the dynamics of the external network interface.

[0050] It should be noted that the equipment grid status detection principle described in this article refers to a mathematical equivalent method that replaces the normal input variables of the equipment with the active and reactive power at the internal potential and the active and reactive power at the internal potential, based on the constraint relationship between the active and reactive power at the internal potential and the filter inductor current and terminal voltage.

[0051] The small-signal offset equation is a standard linearization modeling method. It involves performing a Taylor expansion of the device's nonlinear differential equations near a pre-defined steady-state operating point, neglecting higher-order terms, to obtain equations describing the linear relationships between minute changes in various physical quantities. In this step, the specific operation involves establishing a small-signal equation with the filter inductor current offset and terminal voltage offset as inputs, and the active power offset and reactive power offset at the internal potential as outputs. This achieves the transformation from physically measurable grid-side state quantities to power parameters at the internal potential characterizing the device's control core, providing a direct bridge for analyzing the dynamics of the control system.

[0052] Therefore, this application presents small-signal offset equations characterizing the inputs of the three devices.

[0053] For network construction devices, the following formula is included: ; ; ; .

[0054] For network-connected devices, the following formula is included: ; ; ; .

[0055] For LCC-HVDC devices, the following formula is included: ; .

[0056] in, s For the complex frequency variable in the Laplace domain, P Active power Q Reactive power A For AC electrical quantity amplitude, ω For the frequency of alternating electrical quantities, The phase between two electrical quantities; if and t These are the filter inductor current and terminal voltage, respectively. e and I r These are the internal potential and internal current, respectively; GFM, GFL, and LCC are the grid-building equipment, grid-connecting equipment, and LCC-HVDC rectifier side, respectively. This represents the small-signal offset of the variable near its steady-state operating point; the subscript 0 represents the steady-state value of the variable; and L represents the inductance.

[0057] It should be noted that the principle of network power dynamic response refers to the method of linearizing the power calculation expression to re-establish the power response relationship of the network at the potential port within the device.

[0058] Understandably, power calculation expressions are typically based on the power flow equations or impedance models of AC networks, describing the relationship between port power and port voltage and current, or between internal potential and network impedance. This step uses the output of the aforementioned small-signal offset equation—the power change at the internal potential—as a known input. Using the network equations, it solves for the changes in active and reactive power at the ports, thus establishing the network's active and reactive power response equations at the ports. This completes the dynamic link modeling from internal control variables to external electrical interface variables.

[0059] Therefore, based on the principle of dynamic response of network power, the output of the network port is equivalent to the active power and reactive power of the port.

[0060] The active and reactive power responses of the network at the potential ports within the network-building equipment are as follows: ; .

[0061] The active and reactive power responses of the network at the potential ports of the network devices are as follows: ; .

[0062] The active and reactive power responses of the network at the current port on the rectifier side of the LCC-HVDC are as follows: ; .

[0063] in, s For the complex frequency variable in the Laplace domain, P Active power Q Reactive power A For AC electrical quantity amplitude, ω For the frequency of alternating electrical quantities, The phase between two electrical quantities; if and t These are the filter inductor current and terminal voltage, respectively. e and I r These are the internal potential and internal current, respectively; GFM, GFL, and LCC are the grid-building equipment, grid-connecting equipment, and LCC-HVDC rectifier side, respectively. This represents the small-signal offset of the variable near its steady-state operating point; the subscript 0 represents the steady-state value of the variable; and L represents the inductance.

[0064] It should be noted that, based on the parameters described above, all the formulas mentioned earlier have been clearly expressed. For example... This refers to the small-signal offset of the AC electrical quantity amplitude corresponding to the filter inductor current of the network equipment near the steady-state operating point; other details are omitted.

[0065] It should be noted that all the above formulas constitute the system's equation of motion model. By equating the device's input to active and reactive power at the internal potential, the control loop of the converter device and the power network are distinguished, thus forming the equation of motion model for the converter device, which facilitates the subsequent reshaping of the equation of motion model path. This application, by equating the device's input to active and reactive power at the internal potential, distinguishes the control loop of the converter device and the power network, thus forming the equation of motion model for the converter device, which facilitates the subsequent reshaping of the equation of motion model path.

[0066] In this embodiment, step S20 includes: constructing a first device matrix representing the input-output relationship of various types of devices and a first network matrix representing the power coupling relationship of network nodes according to the motion equation model; based on the first device matrix and the first network matrix, obtaining a transfer function representing the damping characteristics of the system according to the damping torque method, as a first transfer model; extracting the real part and imaginary part of the first transfer model at the critical stability point of the dominant mode to obtain the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient.

[0067] It should be noted that constructing the first device matrix and the first network matrix is ​​a standardization and systematization of the mathematical organization of the motion equation model established in step S10. The first device matrix is ​​a mathematical matrix whose elements are composed of coefficients from the small-signal offset equations of various types of devices (networking devices, network construction devices, and LCC-HVDC devices). It represents the input-output relationship of each type of device, that is, it describes the dynamic transmission relationship from the device control input or internal state to its output power.

[0068] Specifically, the expressions representing the LCC-HVDC rectifier side, network-building equipment, and network-connecting equipment, i.e., the first equipment matrix, include: ; ; ; .

[0069] in, is the DC voltage on the rectifier side of the LCC-HVDC; M represents the transfer function between small signals inside the device or the device matrix; dr is the DC quantity on the rectifier side of the LCC-HVDC; Idr is the DC current on the rectifier side of the LCC-HVDC. The frequency of the internal current on the rectifier side of the LCC-HVCD; The amplitude of the internal current on the rectifier side of the LCC-HVDC; for example This is the transfer function from active power to DC voltage in LCC-HVDC; the rest will not be elaborated further.

[0070] In short, for system-level analysis, these differential / algebraic equations need to be transformed into a more compact, standard matrix form. The first device matrix is ​​the product of this process. It treats each device as a dynamic module, summarizing its internal dynamics using a transfer function matrix, or M-matrix. The elements of the M-matrix are entirely derived from the coefficients of the small-signal equations corresponding to step S10.

[0071] It should be noted that the first network matrix is ​​established based on the system's network topology and parameters, such as line impedance, and characterizes the power coupling relationships between network nodes. That is, it describes how a power change injected by one node affects the voltage and frequency of other nodes through the power grid. By combining the two through interface variables, the state-space equations or algebraic equations describing the entire closed-loop system can be obtained.

[0072] Specifically, the expression representing the network, i.e., the first network matrix, is: .

[0073] To determine the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient, the network expression is expanded as follows: ; ; .

[0074] Here, the J matrix is ​​the network matrix. For example... The LCC device inputs the internal current amplitude and frequency, and the GFM device outputs the active and reactive power network matrix; the rest will not be elaborated.

[0075] In short, the first network matrix extends the equations for a single port to the entire interconnected system. It is a block matrix whose dimensions are determined by the number of devices in the system; in the document example, it is 3×3, corresponding to the three-terminal devices: GFM, GFL, and LCC. It quantifies the dynamic interactions between devices through the power grid and serves as the link connecting the various independent device models.

[0076] Ultimately, the conclusion is as follows: Figure 3 The linearized model shown, Figure 3 This is a linearized block diagram of the motion equation model provided in the embodiments of this application.

[0077] Furthermore, based on the aforementioned combined system matrix, and applying the core idea of ​​the damped torque method, a transfer function characterizing the system's damping properties is constructed. Specifically, this transfer function typically takes a key operating variable of the LCC-HVDC device of interest as its output and a disturbance that may cause oscillations as its input. This first transfer model fully characterizes the system's response to oscillations from a frequency domain perspective.

[0078] It should be noted that, in order to analyze the impact of GFL and GFM devices on the stability of LCC-HVDC, it is necessary to eliminate the internal state variables of GFM and GFL from the above simultaneous equations, ultimately obtaining a concise input-output relationship. This relationship describes how the internal disturbances or interactions of the LCC-HVDC device ultimately affect a key operating variable.

[0079] It should be noted that the first transmission model is: .

[0080] in: ; ; ; .

[0081] Understandably, the first transfer model is the result of this derivation. It is a complex number calculated at the angular frequency of the system's dominant oscillation mode. The above expression is obtained through rigorous matrix operations, including inversion and multiplication. The intermediate matrices a11, a12, a21, and a22 in the expression reflect the dynamic interaction paths between GFM and GFL devices, as well as between them and the LCC. For example, a11 and a22 contain the closed-loop effects formed by the GFM and GFL devices through their own control loops and network coupling.

[0082] Ultimately, the critical stability point of the dominant mode refers to the dominant oscillation mode of the system in the complex plane (s-plane), typically the weakest damped mode, located at the stability boundary, i.e., the system operating state or parameter conditions corresponding to the zero real part. At this critical point, the frequency response value of the first transfer model at the oscillation frequency (corresponding to the imaginary part) of this mode is calculated. The real and imaginary parts of this frequency response value are extracted. According to the theoretical definition of the damped torque method, the real part is directly related to the stabilizing synchronous torque coefficient; the imaginary part, or the imaginary part after a specific transformation, is related to the stabilizing damping torque coefficient. These two coefficients are scalars, quantitatively characterizing the synchronous support capability and damping contribution capability of the analyzed equipment (network-connecting / network-building equipment) to the target equipment (LCC-HVDC) in this critical oscillation mode.

[0083] From this, we can derive the expressions for the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient of the network-building and network-following equipment: , .

[0084] In this embodiment, step S30 includes: constructing the amplitude partial derivative function and phase partial derivative function of the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient with respect to the device path function; based on the partial derivative function, calculating the amplitude sensitivity and phase sensitivity corresponding to each device path according to the mapping relationship between the amplitude and phase of the device path.

[0085] It should be noted that the device path function refers to the expression representing a specific control path (such as the active power-frequency Pf path) of a network-connected device in the model established in step S10. A simple example is provided here: Network device path: ; Network device path: .

[0086] in, , , and These refer to the active frequency path, active voltage path, reactive frequency path, and reactive voltage path of the network equipment, respectively. , , and These refer to the active frequency path, active voltage path, reactive frequency path, and reactive voltage path of the grid-connected equipment, respectively. A represents the amplitude of the equipment path. This refers to the device path phase.

[0087] At this point, the sensitivity can be calculated by establishing the partial derivative function, as detailed below.

[0088] The stabilizing damping torque coefficient has the following amplitude sensitivity to the equipment path: .

[0089] The phase sensitivity of the stabilizing damping torque coefficient to the equipment path is: .

[0090] The sensitivity of the stabilizing synchronous torque coefficient to the amplitude of the equipment path is: .

[0091] The phase sensitivity of the stabilizing synchronous torque coefficient to the equipment path is: .

[0092] Where S represents sensitivity, m represents the device matrix element, and jk represents the device path. In this paper, the device path refers to the transfer function channel from a certain input signal to a certain output signal in the device control model. We uniformly use equi to replace GFM and GFL; simply replace whichever you are calculating.

[0093] It should be noted that in the past, directly solving for parameter sensitivity only revealed how the system parameters could be modified, but it was impossible to reshape the frequency response characteristics of the system path based on parameter sensitivity. However, by using the formula here to solve for the amplitude and phase sensitivity of the device path, and knowing the path sensitivity, the frequency response characteristics of the device path can be reshaped using lead and lag elements. By solving for the sensitivity of the stabilizing damping to the device path, and combining this with subsequent steps, the path of the device's motion equations can be reshaped, increasing the damping of oscillation modes.

[0094] In this embodiment, please refer to Figure 4 , Figure 4 This is a flowchart illustrating step S40 provided in an embodiment of this application. Step S40 includes: Step S41: Determine the target device path to be reshaped based on the amplitude sensitivity and phase sensitivity of the device path.

[0095] It should be noted that step S41 specifically involves determining whether the signs of the damping torque sensitivity and the synchronous torque sensitivity corresponding to the equipment path are consistent; if they are consistent, the target equipment path to be reshaped is determined; if they are inconsistent, it is determined whether the absolute value of the damping torque sensitivity is much greater than the synchronous torque sensitivity; if so, the target equipment path to be reshaped is determined, otherwise the next path is selected for judgment.

[0096] Understandably, when the signs of the damping torque sensitivity and the synchronizing torque sensitivity are the same, this means that by adjusting the amplitude-frequency or phase-frequency characteristics of this path, it is possible to simultaneously improve the damping torque and synchronizing torque of the system in this mode. This is an ideal situation with the strongest synergistic effect. Therefore, the decision logic is to directly modify this path without any trade-offs; the modification will simultaneously enhance the system's damping capacity and synchronizing support capacity.

[0097] Understandably, the discrepancy in sign implies that modifying the path will improve one metric while weakening another, creating a trade-off. In this case, the decision depends on comparing the absolute values ​​of the two. If the absolute value of the damping torque sensitivity is significantly greater than the synchronous torque sensitivity, it indicates that the positive impact of modifying this path on system damping far outweighs the negative impact on synchronization capability. In this case, the branch can be modified, prioritizing a significant improvement in damping. Otherwise, if the absolute values ​​are not significantly different, the net benefit of the modification is unclear or may have side effects; therefore, it is necessary to select the next suitable path for modification for evaluation.

[0098] It should be noted that "far greater than" here is a relative concept, and can be quantified by setting a threshold to achieve precise decision-making. Specifically, before implementing this method, a threshold ratio K is defined by the system designer or operating procedure (e.g., K=5 or K=10, the specific value needs to be tuned according to system characteristics and stability margin requirements). During decision-making, the ratio R of the absolute value of damping torque sensitivity to the absolute value of synchronous torque sensitivity is calculated. If R>K, it is determined to be "far greater than", meeting the modification conditions; otherwise, it is determined not to meet the conditions. The threshold K can be optimized based on historical simulation data, engineering experience, or stability margin targets. The symbols R and K here are not related to those that may appear in other paragraphs; they are only used for illustrative purposes.

[0099] Step S42: Combining the selected input variables and output positions, establish the transfer function of the target device path after adding the damping controller, as the second transfer model. The second transfer model consists of the original path transfer function, the transfer function from the output position to the internal potential control target, and the damping controller transfer function.

[0100] Before introducing step S42, it is necessary to explain that step S42 also includes: selecting input variables and outputs based on the approximate decoupling characteristics of the current inner loop dq axis and the inner loop generated internal potential amplitude frequency of the network-building equipment and the network-following equipment.

[0101] First, a brief introduction to the damping controller. Power oscillation damping controllers are simple in structure and easy to debug; therefore, a typical bandpass filter and lead-lag modules are used to construct the path characteristic reshaping damping controller used here. Its typical formula is: ; ; ; .

[0102] Where ζ is the damping ratio, ωc is the center angular frequency, α is the attenuation factor, θ is the lead or lag angle, and T is the time constant. Specifically, the input variable is selected as the active or reactive power measured at the potential inside the device; the output position is selected at the d-axis or q-axis voltage reference value output from the inner current loop.

[0103] It should be noted that the input variables were selected for two reasons: first, the equipment has built-in active and reactive power measurement devices at the internal potential, so there is no need to add new measurement devices; second, it is to facilitate the reshaping of the frequency response characteristics of the equipment from power at the internal potential to the internal potential.

[0104] It should be noted that the output position selection has two purposes: first, to directly select the output on the output command value of the current inner loop, so that the controller signal does not need to pass through the current inner loop, which can prevent the damping controller from affecting the inner loop control; second, to facilitate the reshaping of the frequency response characteristics of the equipment from power to internal potential.

[0105] Specifically, in the linearized model, the amplitude and frequency of the internal potential output by the inner loop of the network-connected device can be approximately decoupled. The main reason is that the inner loop of the network-connected device employs dual-loop control: a voltage inner loop and a current inner loop. The voltage inner loop allows the terminal voltage to quickly track the internal potential reference value generated by the VSG outer loop. Simultaneously, due to the small value of the filter inductance in the network-connected device, the phase difference between the internal potential generated by the current inner loop and the internal potential of the terminal voltage is small; that is, the phase difference between the actual internal potential phasor output by the current inner loop and the internal potential reference phasor formed by the VSG outer loop is small.

[0106] Specifically, in the linearized model, the relationship between the magnitude of the internal potential and the internal potential along the dq axis is as follows: The internal potential frequency and the dq-axis internal potential, and The relationship is Therefore, it can be approximated that the potential amplitude within the grid-connected equipment is mainly affected by the d-axis of the current inner loop, and the internal potential frequency is mainly affected by the q-axis of the current inner loop and the VSG frequency.

[0107] Understandably, in the past, the impedance characteristics of the equipment were typically reshaped. However, only by establishing the equipment as a set of equations of motion can the equipment be decoupled from the network. According to the previous method, the output position of the power damping controller needs to be selected at the internal potential amplitude and frequency to reshape the path of the equations of motion. However, due to the inherent dq-axis control structure of the equipment, directly selecting the output position is not convenient. Here, by analyzing the approximate decoupling characteristics of the dq-axis control and internal potential amplitude and frequency of the network-connecting and network-building equipment, the problem of selecting the position of the power damping controller is solved.

[0108] Similarly, for grid-connected devices, in the linearized model, the amplitude and frequency of the internal potential output by the inner loop of the grid-connected device can be decoupled. The main reason is that the angle between the internal potential generated by the current inner loop of the grid-connected device and the d-axis of the phase-locked loop is actually the angle between the internal potential and the terminal voltage. Because the filter inductance of the grid-connected device is relatively small, the angle between the actual internal potential phasor output by the current inner loop and the phase-locked reference phasor formed by the phase-locked loop is small. In the linearized model, the relationship between the internal potential amplitude and the dq-axis internal potential is: Internal potential frequency and dq-axis internal potential and The relationship is Therefore, it can be approximated that the internal potential amplitude of the grid-connected equipment is mainly affected by the d-axis of the current inner loop, and the internal potential frequency is mainly affected by the q-axis of the current inner loop and the frequency of the phase-locked loop.

[0109] Where p=d / dt is the differentiation operator, vsg represents the virtual synchronization outer loop of the network-building device, pll represents the phase-locked loop of the network-following device, Lf is the filter inductor, and d and q represent the d-axis and q-axis of the rotating coordinate system, respectively.

[0110] At this point, based on the analysis of the device path amplitude and phase sensitivity, the specific selections are as follows: When reshaping the active frequency path, select active power as the input variable and q-axis voltage reference value as the output position; when reshaping the active voltage path, select active power as the input variable and d-axis voltage reference value as the output position; when reshaping the reactive frequency path, select reactive power as the input variable and q-axis voltage reference value as the output position; when reshaping the reactive voltage path, select reactive power as the input variable and d-axis voltage reference value as the output position.

[0111] Understandably, after selecting the input variables and output positions of the damping controller, it is necessary to calculate the damping controller parameters. The original path transfer function is the unmodified equipment control path model established in step S10; the transfer function from the output position to the internal potential control target describes the dynamic process from the damping controller output signal injection point to the key stable observation point of the system's internal potential; the damping controller transfer function is the part to be designed, typically possessing adjustable gain and phase compensation characteristics. Combining these three parts according to the actual connection relationship of the system constitutes the second transfer model, which is used to analyze the impact of the controller parameters on the overall characteristics of the system.

[0112] Therefore, after a damping controller is installed on a certain path of a device, the expression for that path, i.e., the second transfer model, is: ; in, The transfer function of the device equi after a damping controller has been installed on the jk path. This is the transfer function for the path of device equi when no damping controller is installed; The transfer function of the device equi from Ed or Eq to the magnitude or frequency of its internal potential; The transfer function for the damping controller installed on the jk path for device equi.

[0113] For example Figure 5 As shown, Figure 5 This is a schematic diagram of the network equipment control structure and damping controller configuration provided in the embodiments of this application.

[0114] Step S43: Establish the mapping function relationship between the lead-lag phase and gain parameters of the damping controller and the amplitude and phase of the target device path at the dominant oscillation frequency.

[0115] It should be noted that this step establishes a mathematical relationship between the controller's adjustable parameters and the system performance indicators. The lead / lag phase and gain parameters are adjustable variables in the damped controller's transfer function; the amplitude and phase of the target device path at the dominant oscillation frequency are the desired reshaping of the system's frequency response characteristics. Using frequency response analysis in control theory, a mapping function relationship between the two can be established. This function clarifies the controller gain and phase compensation amounts required to adjust the path's amplitude and phase to the desired values ​​at a specific oscillation frequency.

[0116] Specifically, the relationship between the device path phase and amplitude and the lead / lag phase and gain of the device path damping controller is as follows: ; .

[0117] in, The phase of the path at the dominant oscillation frequency. For leading or lagging phases, For the damping controller gain, It is a function that maps the lead-lag phase and gain of the damping controller to the device path phase; It is a function that maps the lead-lag phase and gain of the damping controller to the amplitude of the device path.

[0118] Step S44: Combining the adjustment direction indicated by the amplitude sensitivity and phase sensitivity, and based on the constraints on phase and amplitude changes during path reshaping, solve the mapping function relationship to obtain the damping controller parameter range that satisfies the constraints, and select parameters from it to reshape the device path frequency response characteristics.

[0119] Understandably, this step involves the specific tuning of the parameters. First, by combining the adjustment directions indicated by the amplitude and phase sensitivities, the desired path amplitude / phase adjustment target—whether to increase or decrease—is determined. Second, constraints on phase and amplitude changes during path reshaping are applied, including practical engineering limitations such as ensuring controller stability, avoiding the introduction of new resonances, output limiting, and not affecting the normal control functions of the equipment. Finally, the adjustment target and constraints are substituted into the mapping function relationship established in step S43 for solution. This may be achieved through analytical calculation or numerical optimization, yielding one or more damping controller parameter ranges that satisfy the constraints. Designers can then select a set of robust parameters (such as the median) for final application.

[0120] Specifically, the constraints include: when reshaping the amplitude-frequency characteristics of the device path, the phase angle of the device path remains within ±5° of the phase angle of the corresponding device path without adding a damping controller, that is: When reshaping the phase frequency characteristics of the device path, the amplitude of the device path remains within ±5dB of the amplitude of the corresponding device path without adding a damping controller, i.e. .

[0121] Therefore, by obtaining the transfer function of the corresponding path after adding the power damper, the relationship between the lead-lag phase and gain parameters of the power damper and the corresponding path transfer function can be obtained. Combined with the path sensitivity value, the specific range of the lead-lag controller phase and gain can be solved, and appropriate controller parameters can be selected.

[0122] Understandably, in the past, damper parameter calculations required calculations within the entire system. However, here, after obtaining the path sensitivity value through previous calculations, the damping controller parameters can be designed directly for a single converter device, reducing the calculation difficulty. Network devices with different parameters can be designed separately without having to be repeatedly calculated within the large system.

[0123] Furthermore, this application provides a feasible implementation method to verify the effectiveness of the damping controller design method proposed in this application. A system is built in MATLAB / Simulink as follows: Figure 2 The original mathematical model of the system is shown, and the system parameters are set as follows.

[0124] Table 1. Network Construction Equipment Parameters:

[0125] Table 2. Network-connected equipment parameters:

[0126] Table 3. LCC-HVDC Equipment Parameters:

[0127] The filter parameters for the LCC-HVDC device are referenced from the Thyristor-Based HVDC Transmission System model provided by MATLAB / Simulink. The network parameters are shown in Table 4.

[0128] Table 4. Network Parameters:

[0129] Table 5. Transformer Parameters:

[0130] It should be noted that... Figure 2 In the system shown, the ratio of top net to bottom net decreases to 1.93:8.07. At this point, the system is at a critical stability point. After linearizing the system according to step S10, the following is obtained: Figure 3 The diagram shows a linearized model block diagram. A comparison of the Averaged Model (AVM) and the Detailed Switch Model (DSM) is shown below. Figure 6 As shown, Figure 6 This is a waveform comparison diagram of the linearized model and the original nonlinear model provided in the embodiments of this application. The waveforms of the two are basically consistent, therefore the average value model can replace the detailed switching model.

[0131] The amplitude sensitivity and phase sensitivity of the network-building equipment and the network-following equipment paths are obtained by using step S20, as shown in Tables 6 and 7.

[0132] Table 6. Amplitude and phase sensitivity of the equivalent damping torque coefficient:

[0133] Table 7. Amplitude and phase sensitivity of the equivalent synchronous torque coefficient:

[0134] Understandably, by analyzing the sensitivity of the equivalent damping torque coefficient and the equivalent synchronous torque coefficient of the equipment, it can be found that the amplitude-frequency characteristics of the active frequency branch of the grid-connected equipment need to be reduced first. By reducing the amplitude-frequency characteristics of the active frequency branch, not only can the damping torque coefficient be improved to solve the problem of swaying and oscillation instability, but the synchronous torque coefficient can also be improved to prevent the system from losing synchronization.

[0135] The schematic diagram of the damping controller configuration location for the active frequency branch of the network equipment is shown below. Figure 5 As shown, the specific expression for the damper is: ; ; ; .

[0136] Where ζ is the damping ratio, ωc is the center angular frequency, α is the attenuation factor, θ is the lead or lag angle, T is the time constant, and LL represents the lead-lag module (Lead-Lag).

[0137] With the addition of a damping controller, the transfer function of the active frequency branch of the grid-connected equipment can be expressed as follows. The phase relationship between the active frequency branch phase of the grid-connected equipment and the amplitude-phase relationship of the damping controller for the active frequency branch of the grid-connected equipment is as follows: .

[0138] The phase relationship between the amplitude of the active frequency branch of the grid-connecting equipment and the amplitude of the damping controller of the active frequency branch of the grid-connecting equipment is as follows: .

[0139] Meanwhile, the phase angle is within ±5° of the reference value of the amplitude-frequency branch transfer function without the addition of a damping controller, that is: .

[0140] The above formula can be used to plot a three-dimensional graph of the system amplitude as a function of the lead-lag phase angle and gain. (Refer to...) Figure 7 .exist Figure 7 middle, The phase of the lead-lag module in the active frequency branch of the network equipment. This refers to the gain of the active frequency branch damping controller for network equipment. For example... Figure 7 As shown in (a), the gray plane represents the amplitude of the active frequency branch of the grid controller without a damped controller; as Figure 7 As shown in (b), the intersection of the gray plane and the colored surface is projected onto the bottom surface as a gray curve. Controller parameters within the gray curve can decrease the amplitude, while parameters outside the gray curve can increase the amplitude. The opaque colored surface on the transparent colored surface represents the parameter range that satisfies the phase condition, and its projection onto the bottom surface is a black curve. Therefore, the lead-lag angle of the active frequency branch controller of the network equipment is selected as 15°, and the damping gain is 0.4.

[0141] By plotting the amplitude-frequency and phase-frequency characteristics of the active frequency branch of the network equipment before and after adding the damping controller, as shown in the figure... Figure 8 As shown, Figure 8 This is a schematic diagram illustrating the reshaping of the amplitude-frequency characteristics of the active frequency path of the network-building equipment provided in this application embodiment. Figure 8 middle, It is the transfer function of the active frequency branch when the grid equipment does not have a damping controller. This is the transfer function of the active frequency branch of the network equipment after adding a damping controller. As can be seen from the amplitude-frequency response, the system amplitude decreases at the oscillation frequency, while the phase change at the oscillation frequency is minimal, thus achieving a reshaping of the amplitude-frequency characteristics of the active frequency branch of the network equipment.

[0142] It should be noted that the physical meaning of the damping controller in the active frequency branch of the grid-connected equipment is as follows: From the amplitude-frequency characteristics of the active frequency branch of the grid-connected equipment, it can be seen that although the grid-connected equipment has a high equivalent active inertia in the electromechanical time scale, its equivalent active inertia gradually decreases with increasing frequency. The ability of the grid-connected equipment to resist unbalanced active power oscillations at the internal potential becomes increasingly weak. This is one of the important reasons for the decrease in the interactive damping of the DC voltage time scale between the grid-connected equipment and the connected equipment when the capacity of the grid-connected equipment decreases. By adding a damping controller to this branch, the equivalent active inertia in the DC voltage time scale is increased, which can effectively increase the ability of the grid-connected equipment to resist DC voltage time scale oscillations. Furthermore, to verify the function of the active frequency branch controller of the network equipment in the time domain, time-domain simulation verification was performed in MATLAB / Simulink, such as... Figure 9As shown. In the first 0-2 seconds, the ratio of the capacity of the network-connecting equipment to that of the network-following equipment was 8:2. From the 2nd to the 3rd second, the ratio of the network-connecting equipment capacity to that of the network-following equipment was adjusted linearly from 8:2 to 8.1:1.9, and the system exhibited oscillation and divergence. At the 12th second, the damping controller of the active frequency branch of the network-connecting equipment was put into operation, and it was observed that the oscillation was suppressed, verifying the effectiveness of the damping controller.

[0143] In addition, please refer to Figure 10 , Figure 10 This is a structural block diagram of a DC voltage scale POD configuration device provided in an embodiment of this application. A second aspect of this application relates to a DC voltage scale POD configuration device, comprising: The model building module is used to convert the input quantities of various types of equipment in the power transmission system, including the grid-connected control station, into power parameters at the internal potential, and to convert the output quantities of the network port into port power parameters, so as to establish the motion equation model of the equipment; among them, the various types of equipment include grid-connected equipment, grid-connected equipment, and LCC-HVDC equipment.

[0144] It should be noted that this module is the data processing and basic modeling unit for the device. Its function is to convert input quantities into power parameters at the internal potential and network port output quantities into port power parameters, essentially performing unified dynamic power modeling for both the device and network ends. Specifically, based on the principle of equivalent detection of device grid state, it maps the electrical quantities of the device (such as current and voltage) into power variables characterizing its internal dynamics; simultaneously, based on the principle of dynamic power response of the network, it converts the electrical quantities of the network port into power absorbed or emitted by the network. By establishing the relationship between these two sets of power variables, a motion equation model describing the dynamic interaction between the device and the network is ultimately formed. This model is the foundation for all subsequent analyses.

[0145] The coefficient calculation module is used to obtain the stabilizing damping torque coefficient and stabilizing synchronization torque coefficient of the grid-connecting equipment and the grid-building equipment for the LCC-HVDC equipment based on the damping torque method and the motion equation model.

[0146] It should be noted that this module is the stability quantification and evaluation unit of the device. Its function is based on the damping torque method, obtaining the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient through a motion equation model. Specifically, the process is as follows: First, based on the motion equation model, a first device matrix representing the device's dynamics and a first network matrix representing network connections are constructed. Then, based on the damping torque method theory, a first transfer model representing the system's stability characteristics under specific oscillation modes is derived. Finally, by analyzing the characteristics of this transfer function near the critical point of the dominant oscillation mode, the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient are extracted analytically or numerically. These two coefficients quantify the system's damping capability against oscillations and its ability to maintain synchronization, respectively.

[0147] The sensitivity acquisition module is used to acquire the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient with respect to the four paths of active frequency, active voltage, reactive frequency and reactive voltage of the grid-connecting equipment and the grid-connecting equipment.

[0148] It should be noted that this module is the path influence analysis unit of the device. Its function is to obtain the amplitude and phase sensitivities of the four paths. Specifically, for the two stability coefficients calculated in step S20, first-order partial derivative models (i.e., sensitivity functions) of their amplitude and phase relative to the transfer functions of the four control paths (active power-frequency, active power-voltage, reactive power-frequency, and reactive power-voltage) of the grid-connecting / connecting equipment are established. Subsequently, at the current system operating point or the frequency of interest, the specific values ​​of these sensitivity functions are calculated, thus obtaining the amplitude and phase sensitivities of each path. These values ​​reveal the degree and direction of the influence of the dynamic characteristics of each equipment control path on the overall stability of the system.

[0149] The reshaping control module is used to obtain damping controller parameters based on amplitude sensitivity and phase sensitivity, combined with the input variables and output position of the selected damping controller, in order to reshape the device path frequency response characteristics.

[0150] It should be noted that this module is the controller design unit for the device. Its function is based on sensitivity analysis to obtain damping controller parameters. The specific process includes: First, selecting the most effective target device path based on sensitivity analysis results (such as sign consistency and absolute value comparison). Next, combining the selected damping controller input signal and output injection location, establishing a closed-loop second transfer model including the controller, the original device path, and the rest of the system. Then, establishing a mathematical mapping function relationship between the controller's adjustable parameters (gain, lead / lag time constant) and the amplitude and phase of the target path at key frequency points. Finally, based on the adjustment direction indicated by the sensitivity and engineering constraints, solving this mapping relationship yields one or more sets of feasible damping controller parameters, thereby completing the purposeful reshaping of the device path's frequency response characteristics.

[0151] Compared with the prior art, the beneficial effects of the DC voltage scale POD configuration device provided in this application are the same as those of the DC voltage scale POD configuration method provided in the above embodiments, and will not be repeated here.

[0152] Based on the methods in the above embodiments, please refer to Figure 11This application provides an electronic device that may include a processor, a communications interface, a memory, and a communication bus. The processor, communications interface, and memory communicate with each other via the communication bus. The processor can invoke logical instructions stored in the memory to execute the methods described in the above embodiments.

[0153] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0154] Based on the methods in the above embodiments, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0155] Based on the methods in the above embodiments, this application provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0156] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0157] The method steps in this application embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an ASIC.

[0158] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0159] It is understood that the various numerical designations used in the embodiments of this application are merely for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0160] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A DC voltage scale POD configuration method, characterized in that, include: Step S10: Convert the input quantities of various types of equipment in the power transmission system, including the grid control station, into power parameters at the internal potential. The network port output is then converted into port power parameters to establish a motion equation model for the device; wherein, the various types of devices include network-connecting devices, network-building devices, and LCC-HVDC devices; Step S20: Based on the damping torque method, obtain the stabilizing damping torque coefficient and stabilizing synchronization torque coefficient of the grid-connecting equipment and the grid-building equipment for the LCC-HVDC equipment through the motion equation model; Step S30: Obtain the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient with respect to the four paths of active frequency, active voltage, reactive frequency and reactive voltage of the grid-connecting equipment and the grid-connecting equipment. Step S40: Based on the amplitude sensitivity and phase sensitivity, and combined with the selected input variables and output positions of the damping controller, obtain the damping controller parameters to reshape the device path frequency response characteristics.

2. The DC voltage scale POD configuration method as described in claim 1, characterized in that, Step S10 includes: Based on the principle of equivalent detection of equipment grid status, small-signal offset equations are established for various types of equipment near the steady-state operating point. The small-signal offset equations map the filter inductor current and terminal voltage of the equipment to the active power and reactive power at the internal potential. Based on the principle of network power dynamic response, and using the small-signal offset equation as input, the active and reactive power response equations of the network at the port are established by utilizing the power solution expression.

3. The DC voltage scale POD configuration method as described in claim 1, characterized in that, Step S20 includes: Based on the motion equation model, a first device matrix representing the input-output relationship of each type of device and a first network matrix representing the power coupling relationship of network nodes are constructed. Based on the first device matrix and the first network matrix, a transfer function characterizing the system's damping characteristics is obtained according to the damping torque method, which serves as the first transfer model. Extract the real and imaginary parts of the first transmission model at the critical stability point of the dominant mode to obtain the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient.

4. The DC voltage scale POD configuration method as described in claim 1, characterized in that, Step S30 includes: For the stabilizing damping torque coefficient and the stabilizing synchronous torque coefficient, construct the magnitude partial derivative function and the phase partial derivative function with respect to the equipment path function; Based on the partial derivative function, the amplitude sensitivity and phase sensitivity corresponding to each device path are calculated according to the mapping relationship between the amplitude and phase of the device path.

5. The DC voltage scale POD configuration method as described in claim 1, characterized in that, Step S40 includes: Step S41: Determine the target device path to be reshaped based on the amplitude sensitivity and phase sensitivity of the device path; Step S42: Combining the selected input variables and output positions, establish the transfer function of the target device path after adding the damping controller, as the second transfer model. The second transfer model consists of the original path transfer function, the transfer function from the output position to the internal potential control target, and the damping controller transfer function. Step S43: Establish the mapping function relationship between the lead-lag phase and gain parameters of the damping controller and the amplitude and phase of the target device path at the dominant oscillation frequency; Step S44: Combining the adjustment direction indicated by the amplitude sensitivity and phase sensitivity, and based on the constraints on phase and amplitude changes during path reshaping, solve the mapping function relationship to obtain the damping controller parameter range that satisfies the constraints, and select parameters from it to reshape the device path frequency response characteristics.

6. The DC voltage scale POD configuration method as described in claim 5, characterized in that, Step S41 includes: Determine whether the signs of the damping torque sensitivity and the synchronous torque sensitivity corresponding to the equipment path are consistent. If they are consistent, determine the target equipment path to be reshaped. If they are inconsistent, determine whether the absolute value of the damping torque sensitivity is much greater than the synchronous torque sensitivity. If so, determine the target equipment path to be reshaped; otherwise, select the next path for judgment.

7. The DC voltage scale POD configuration method as described in claim 1, characterized in that, Step S42 includes the following: The selection of input and output variables is based on the approximate decoupling characteristics of the dq-axis of the current inner loop and the amplitude and frequency of the generated internal potential of the grid-connected and grid-connected equipment. The input variable is selected as the active or reactive power measured at the internal potential of the equipment. The output position is selected at the d-axis or q-axis voltage reference value output by the current inner loop. Specifically: when reshaping the active frequency path, the input variable is active power and the output position is the q-axis voltage reference value; when reshaping the active voltage path, the input variable is active power and the output position is the d-axis voltage reference value; when reshaping the reactive frequency path, the input variable is reactive power and the output position is the q-axis voltage reference value; when reshaping the reactive voltage path, the input variable is reactive power and the output position is the d-axis voltage reference value.

8. A DC voltage scale POD configuration device, characterized in that, include: The model building module is used to convert the input quantities of various types of equipment in the power transmission system, including the grid-connected control station, into power parameters at the internal potential, and to convert the output quantities of the network port into port power parameters, so as to establish the motion equation model of the equipment; wherein, the various types of equipment include grid-connected equipment, grid-connected equipment, and LCC-HVDC equipment; The coefficient calculation module is used to obtain the stabilizing damping torque coefficient and stabilizing synchronization torque coefficient of the grid-connecting equipment and the grid-building equipment for the LCC-HVDC equipment based on the damping torque method and the motion equation model. The sensitivity acquisition module is used to acquire the amplitude sensitivity and phase sensitivity of the stabilizing damping torque coefficient and the stabilizing synchronization torque coefficient with respect to the four paths of active frequency, active voltage, reactive frequency and reactive voltage of the grid-connecting equipment and the grid-connecting equipment. The reshaping control module is used to obtain damping controller parameters based on the amplitude sensitivity and phase sensitivity, combined with the input variables and output position of the selected damping controller, in order to reshape the path frequency response characteristics of the device.

9. An electronic device, characterized in that, include: Memory, one or more processors; The memory is coupled to the one or more processors, and the memory is used to store computer program code, the computer program code including computer instructions; The one or more processors invoke the computer instructions to cause the electronic device to perform the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium comprising instructions, characterized in that, When the instructions are executed on an electronic device, the electronic device causes the electronic device to perform the method as described in any one of claims 1 to 7.

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