A modeling method for characterizing the active-frequency response of typical grid-connected control systems

Abstract

This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical network control systems, belonging to the field of power system automation and control technology. The method includes: Step 1: Obtaining key parameters of the circuit's preset parameter type, and simultaneously obtaining the key parameters of the controller; Step 2: Determining the power angle characteristic coefficient and the angular frequency base value; Step 3: Constructing a transfer function of the preset type based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset type, the power angle characteristic coefficient, and the angular frequency base value; Step 4: Constructing a unified active power-frequency transfer function model in a general form, and simultaneously determining a network type parameter table; Step 5: Determining the key values ​​in the unified active power-frequency transfer function model based on the network type parameter table, and then solving the unified active power-frequency transfer function model. This method intuitively obtains the relationships between various control parameters and can greatly reduce the workload when analyzing dynamic characteristics such as damping and inertia.

Description

Technical Field

[0001] This invention relates to the field of power system automation and control technology, and in particular to a modeling method for characterizing the active-frequency response characteristics of typical grid control systems. Background Technology

[0002] With the increasing complexity of power systems and the growing proportion of renewable energy integration, power system stability and control issues have received increasing attention. Active power-frequency control, as a crucial component of power system stability control, has a significant impact on the overall system performance through its control strategies and response characteristics.

[0003] In existing technologies, network control is typically studied using traditional active-frequency characteristic analysis models (such as those based on simple linearization models or empirical modeling methods). While these methods can describe the active-frequency relationship in certain specific situations, they suffer from the following drawbacks: First, the models have limited applicability and struggle to uniformly characterize the active-frequency response characteristics of different types of network control. Second, traditional modeling methods fail to effectively integrate circuit and controller parameters, resulting in insufficient model accuracy. Third, existing models lack universal optimization strategies for optimizing active-frequency characteristics, limiting their adaptability to complex systems.

[0004] Therefore, this invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. Summary of the Invention

[0005] This invention provides a modeling method for characterizing the active-frequency response of typical grid-connected control systems. It establishes active-frequency transfer functions by analyzing Pf droop control, VSG control, and DC voltage matching control. Based on the characteristics of each transfer function, it summarizes the consistency of several grid-connected control systems in mathematical models and proposes a unified transfer function model. Based on this unified transfer function model, the relationship between various control parameters can be intuitively obtained, and the workload can be greatly reduced when analyzing dynamic characteristics such as damping and inertia.

[0006] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems, comprising:

[0007] Step 1: Obtain the key parameters of the circuit's preset parameter type, and at the same time, obtain the key parameters of the controller;

[0008] Step 2: Determine the power angle characteristic coefficient and the angular frequency base value based on the key parameters of the circuit's preset parameter type and the key parameters of the controller's preset parameter type;

[0009] Step 3: Construct a transfer function of the preset type based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset type, the power angle characteristic coefficient, and the angular frequency base value;

[0010] Step 4: Construct a general form of unified active-frequency transfer function model based on the preset type of transfer function, and at the same time, determine the parameter table of network type.

[0011] Step 5: Determine the key values ​​in the unified active-frequency transfer function model based on the network type parameter table, and then solve the unified active-frequency transfer function model.

[0012] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems, obtaining key parameters of a preset parameter type for the circuit, and simultaneously obtaining key parameters of the controller, including:

[0013] Key parameters of the first preset parameter type of the circuit are obtained based on the preset equipment technical documents;

[0014] The key parameters of the second preset parameter type are determined based on the key parameters of the first preset parameter type of the circuit.

[0015] The type of key parameters corresponding to each controller type is determined based on the preset controller type and the preset type-parameter database;

[0016] Based on a preset parameter type-method database, the acquisition method for each type of key parameter is determined, thereby identifying several key parameters corresponding to each controller type.

[0017] This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical network control systems. The controller types include: Pf droop control, VSG control, and DC voltage matching control.

[0018] This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical network control systems. Based on key parameters of a preset parameter type for the circuit, key parameters of a preset controller type, power angle characteristic coefficients, and angular frequency base values, a transfer function of a preset type is constructed, including:

[0019] The transfer functions for Pf droop control, VSG control, and DC voltage matching control are constructed based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, and the angular frequency base value, respectively.

[0020] This invention provides a modeling method for characterizing the active-frequency response of typical network control systems. It constructs a general-form unified active-frequency transfer function model based on a transfer function of a preset type, including:

[0021] Structural analysis is performed on the transfer functions of Pf droop control, VSG control, and DC voltage matching control. Based on the structural analysis results, the common transfer characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control are determined.

[0022] The common transfer characteristics of the transfer function models based on Pf droop control, VSG control, and DC voltage matching control determine the general form of the unified active-frequency transfer function model.

[0023] This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical grid-connected control systems. Based on key parameters of preset circuit parameter types, key parameters of preset controller types, power characteristic coefficients, and angular frequency base values, transfer functions for Pf droop control, VSG control, and DC voltage matching control are constructed, including:

[0024] Based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset Pf droop characteristic expression, the small-signal model of Pf droop control is determined through a preset analysis method.

[0025] Based on the preset first expression, the small-signal model of Pf droop control is organized to determine the initial function of Pf droop control.

[0026] The initial function of Pf droop control is optimized based on the preset first optimization method, thereby determining the initial transfer function of Pf droop control:

[0027]

[0028] Wherein, ΔP1 e (s) represents the disturbance component of active power corresponding to the Pf droop control, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b ω is the reference frequency, s is the complex frequency variable in the preset analysis method, and ω is the reference frequency. p K is the cutoff frequency corresponding to the preset first optimization method. p The gain is controlled proportionally.

[0029] The small-signal model of VSG control is determined based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset mathematical model of VSG control.

[0030] Based on the preset second expression, the small-signal model of VSG control is organized to determine the initial function of VSG control:

[0031]

[0032] Wherein, ΔP2 e (s) represents the disturbance component of the active power corresponding to VSG control, J is the virtual moment of inertia, and D is the virtual damping coefficient.

[0033] Structural and dual analyses are performed on the converter and synchronous machine, and the corresponding matching relationship between the inverter DC voltage and the synchronous machine speed is determined based on the results of the structural and dual analyses.

[0034] Based on the corresponding matching relationship between inverter DC voltage and synchronous machine speed, the comparative analysis quantity is changed from active power output to DC voltage output, and then the equations of the inverter DC side and AC side are determined by combining the preset circuit relationship.

[0035] The initial function for DC voltage matching control is determined based on a pre-defined analysis method;

[0036] The initial function of the voltage matching control is optimized based on the preset second optimization method, thereby determining the transfer function of the DC voltage matching control:

[0037]

[0038] Among them, ΔP3 e (s) represents the disturbance component of active power corresponding to DC voltage matching control, C dc K is the equivalent capacitance on the DC side. dc For the virtual DC damping control gain, K ω is the damping coefficient.

[0039] 6. This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. The general form of the unified active-frequency transfer function model is as follows: Wherein, ΔP e (s) represents the disturbance component of active power in a unified form, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b is the reference frequency, s is the complex frequency variable in the preset analysis method, A is the inertia coefficient, B is the damping coefficient, C is the constant coefficient, and B′ is the molecular damping coefficient.

[0040] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical grid-connected control systems, determining a unified active-frequency transfer function model, including:

[0041] Obtain and analyze the system's performance requirements, and determine the model optimization objectives based on the analysis results;

[0042] Based on the model optimization objective and the preset objective-parameter data table, several key parameters to be optimized are determined.

[0043] Based on a pre-defined target-method database, the corresponding parameter optimization method is determined, and the key parameters to be optimized are optimized.

[0044] The performance of the optimized unified active-frequency transfer function model is verified based on the preset optimization analysis method, and the performance coefficients of the optimized unified active-frequency transfer function model are determined.

[0045] The optimization process continues until the performance coefficient of the optimized unified active-frequency transfer function model is greater than the preset performance coefficient.

[0046] The optimized unified active-frequency transfer function model is then determined as the final unified active-frequency transfer function model.

[0047] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. The model optimization objectives include: improving frequency regulation capability, enhancing system damping, improving dynamic response speed, and improving system stability.

[0048] Compared with the prior art, the beneficial effects of this application are as follows:

[0049] By establishing active-frequency transfer functions for Pf droop control, VSG control, and DC voltage matching control, and based on the characteristics of each transfer function, the consistency of several network control types in mathematical models is summarized, and a unified transfer function model is proposed. Based on this unified transfer function model, the relationship between various control parameters can be obtained intuitively, and the workload can be greatly reduced when analyzing dynamic characteristics such as damping and inertia. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0051] Figure 1 This is a flowchart illustrating a modeling method for characterizing the active-frequency response characteristics of typical network control, provided by an embodiment of the present invention.

[0052] Figure 2 This is the control block diagram for the drooping portion of Pf;

[0053] Figure 3 This is the control block diagram of VSG;

[0054] Figure 4 This is the block diagram of the optimized Pf droop control model;

[0055] Figure 5 This is the optimized DC voltage matching control block diagram. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0057] Example 1:

[0058] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems, such as... Figure 1 As shown, it includes:

[0059] Step 1: Obtain the key parameters of the circuit's preset parameter type, and at the same time, obtain the key parameters of the controller;

[0060] Step 2: Determine the power angle characteristic coefficient and the angular frequency base value based on the key parameters of the circuit's preset parameter type and the key parameters of the controller's preset parameter type;

[0061] Step 3: Construct a transfer function of the preset type based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset type, the power angle characteristic coefficient, and the angular frequency base value;

[0062] Step 4: Construct a general form of unified active-frequency transfer function model based on the preset type of transfer function, and at the same time, determine the parameter table of network type.

[0063] Step 5: Determine the key values ​​in the unified active-frequency transfer function model based on the network type parameter table, and then solve the unified active-frequency transfer function model.

[0064] In this embodiment, the key parameters of the preset parameter type include line parameters (such as resistance, inductance, and capacitance) and node parameters (such as bus voltage).

[0065] In this embodiment, the key parameters of the controller include control gain, time constant, and filter cutoff frequency.

[0066] In this embodiment, the key values ​​in the unified active-frequency transfer function model include: inertia coefficient, damping coefficient, constant coefficient, and molecular damping coefficient.

[0067] In this embodiment, the active power-frequency transfer function model is used to describe the relationship between dynamic frequency changes and active power changes in a power system. This model is mainly used to study the dynamic characteristics of power systems, such as frequency regulation, the impact of load fluctuations on frequency, and the design of primary and secondary frequency regulation control strategies.

[0068] In this embodiment, the grid-formation parameter table is a set of key parameters used to distinguish and define different grid-formation (GFM) control strategies. The purpose of this parameter table is to define specific control parameters according to the implementation method of different grid-formation control strategies. The grid-formation parameter table can be as follows:

[0069]

[0070] The beneficial effects of the above technical solution are as follows: By establishing the active power-frequency transfer function for Pf droop control, VSG control, and DC voltage matching control, and based on the characteristics of each transfer function, the consistency of several network control types in mathematical models is summarized, and a unified transfer function model is proposed. Based on this unified transfer function model, the relationship between each control parameter can be obtained intuitively, and the workload can be greatly reduced when analyzing dynamic characteristics such as damping and inertia.

[0071] Example 2:

[0072] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems, obtaining key parameters of a preset parameter type for the circuit, and simultaneously obtaining key parameters of the controller, including:

[0073] Key parameters of the first preset parameter type of the circuit are obtained based on the preset equipment technical documents;

[0074] The key parameters of the second preset parameter type are determined based on the key parameters of the first preset parameter type of the circuit.

[0075] The type of key parameters corresponding to each controller type is determined based on the preset controller type and the preset type-parameter database;

[0076] Based on a preset parameter type-method database, the acquisition method for each type of key parameter is determined, thereby identifying several key parameters corresponding to each controller type.

[0077] In this embodiment, the key parameters of the first preset parameter type include circuit parameters: output voltage and grid connection point voltage;

[0078] In this embodiment, the key parameter of the second preset parameter type is the line impedance.

[0079] In this embodiment, the controller type and its parameters are as follows: Pf droop control: droop coefficient, low-pass filter parameters; VSG control: virtual inertia, virtual damping; DC voltage matching control: DC voltage matching coefficient, virtual damping coefficient.

[0080] The beneficial effects of the above technical solution are as follows: By acquiring key parameters of the circuit and controller based on equipment technical documents and a pre-set database, an automated and standardized parameter acquisition process is achieved. Based on the circuit and controller type, key parameters and their acquisition methods are accurately determined, improving modeling efficiency and accuracy, simplifying the parameter collection process, ensuring compatibility with different controller types, providing reliable data support for modeling the active power-frequency response characteristics of network control, and enhancing the flexibility and feasibility of system design and optimization.

[0081] Example 3:

[0082] This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical network control systems. The controller types include: Pf droop control, VSG control, and DC voltage matching control.

[0083] In this embodiment, Pf droop control is a control strategy based on the linear droop relationship of the power-frequency (Pf) characteristic, used to achieve dynamic adjustment of the grid frequency by the power generation equipment. In this control, the frequency deviation is proportional to the output active power, thereby ensuring the rationality of power allocation and the stability of the grid frequency. Grid-type control is achieved by simulating the primary frequency regulation and excitation characteristics of a synchronous generator, and is the simplest and most common grid-type control strategy. The droop characteristic expression is as follows.

[0084]

[0085] Where ω0 is the initial value of the angular frequency, P e For the grid-type converter to output active power, P e These are active power reference values; all parameters above are per-unit values. ω B The angular frequency base value is taken as 100π rad / s, K p P is the droop factor, δ is the output phase of the grid-side converter, and P is the voltage drop factor. ref This is the expected output active power value of the grid-connected converter, such as... Figure 2 This is the control block diagram for the drooping portion of Pf;

[0086] In this embodiment, VSG control simulates the rotor inertial and damping characteristics of a synchronous generator to achieve the inertial response and frequency support functions of power electronic equipment. This control strategy can enhance the dynamic performance and frequency stability of the power grid, and is particularly suitable for high-proportion renewable energy scenarios. VSG control achieves grid-type control by simulating the second-order equations of synchronous generator rotor motion. Compared with droop control, it can more accurately simulate the operating characteristics of synchronous machines. The control block diagram of VSG is shown below. Figure 3 As shown, the mathematical model for VSG control is:

[0087]

[0088] Where J is the virtual inertia and D is the virtual damping;

[0089] In this embodiment, DC voltage matching control is used for power distribution and frequency regulation on the DC side, achieving power sharing among different devices by controlling the DC bus voltage. This method is commonly used in DC microgrids and flexible DC transmission systems.

[0090] The beneficial effects of the above technical solution are as follows: by modeling three typical control types, namely Pf droop control, VSG control and DC voltage matching control, respectively, extracting their dynamic characteristics and achieving unification, it effectively adapts to a variety of control strategies, simplifies the modeling process of active power-frequency response characteristics, improves analysis and design efficiency, and provides theoretical support for optimizing the dynamic performance and stability of the system.

[0091] Example 4:

[0092] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. Based on key parameters of a preset parameter type for the circuit, key parameters of a preset type for the controller, power angle characteristic coefficients, and angular frequency base values, a transfer function of a preset type is constructed, including:

[0093] The transfer functions for Pf droop control, VSG control, and DC voltage matching control are constructed based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, and the angular frequency base value, respectively.

[0094] The beneficial effects of the above technical solution are: by constructing the transfer functions of Pf droop control, VSG control and DC voltage matching control, data support is provided for the subsequent extraction of their common transmission characteristics.

[0095] Example 5:

[0096] This invention provides a modeling method for characterizing the active-frequency response of typical network control systems. It constructs a general-form unified active-frequency transfer function model based on a transfer function of a preset type, including:

[0097] Structural analysis is performed on the transfer functions of Pf droop control, VSG control, and DC voltage matching control. Based on the structural analysis results, the common transfer characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control are determined.

[0098] Based on the common transfer characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control, a general form of unified active-frequency transfer function model is determined. In this embodiment, the common transfer characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control are determined based on the structural analysis results. This involves a comparative analysis of the structures of the three transfer functions, revealing the following commonalities: First-order dynamic characteristics: Both Pf droop control and DC voltage matching control exhibit first-order dynamic characteristics. The structure of the VSG control transfer function includes second-order inertial response characteristics, but in some cases, it can be simplified to first-order characteristics by appropriately adjusting the virtual damping coefficient and inertia. Each controller exhibits a dynamic adjustment relationship between input power and output frequency, and has transfer characteristics dominated by gain and time constant.

[0099] The beneficial effects of the above technical solution are as follows: by constructing the transfer functions of Pf droop control, VSG control and DC voltage matching control, extracting their common transmission characteristics, and forming a unified active power-frequency transfer function model, it is possible to uniformly describe the dynamic characteristics of different control strategies, improve the model's versatility and analysis efficiency, and provide theoretical support for power grid stability optimization.

[0100] Example 6:

[0101] This invention provides a modeling method for characterizing the active power-frequency response characteristics of typical grid control systems. Based on key parameters of a preset circuit parameter type, key parameters of a preset controller type, power characteristic coefficients, and angular frequency base values, transfer functions for Pf droop control, VSG control, and DC voltage matching control are constructed, including:

[0102] Based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset Pf droop characteristic expression, the small-signal model of Pf droop control is determined through a preset analysis method.

[0103] Based on the preset first expression, the small-signal model of Pf droop control is organized to determine the initial function of Pf droop control.

[0104] The initial function of Pf droop control is optimized based on the preset first optimization method, thereby determining the initial transfer function of Pf droop control:

[0105]

[0106] Wherein, ΔP1 e (s) represents the disturbance component of active power corresponding to the Pf droop control, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b ω is the reference frequency, s is the complex frequency variable in the preset analysis method, and ω is the reference frequency. p K is the cutoff frequency corresponding to the preset first optimization method. p The gain is controlled proportionally.

[0107] The small-signal model of VSG control is determined based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset mathematical model of VSG control.

[0108] Based on the preset second expression, the small-signal model of VSG control is organized to determine the initial function of VSG control:

[0109]

[0110] Wherein, ΔP2 e (s) represents the disturbance component of the active power corresponding to VSG control, J is the virtual moment of inertia, and D is the virtual damping coefficient.

[0111] Structural and dual analyses are performed on the converter and synchronous machine, and the corresponding matching relationship between the inverter DC voltage and the synchronous machine speed is determined based on the results of the structural and dual analyses.

[0112] Based on the corresponding matching relationship between inverter DC voltage and synchronous machine speed, the comparative analysis quantity is changed from active power output to DC voltage output, and then the equations of the inverter DC side and AC side are determined by combining the preset circuit relationship.

[0113] The initial function for DC voltage matching control is determined based on a pre-defined analysis method;

[0114] The initial function of the voltage matching control is optimized based on the preset second optimization method, thereby determining the transfer function of the DC voltage matching control:

[0115]

[0116] Among them, ΔP3 e (s) represents the disturbance component of active power corresponding to DC voltage matching control, C dc K is the equivalent capacitance on the DC side. dc This is the virtual DC damping control gain.

[0117] In this embodiment, the preset analysis method is to use Laplace transform and linearization analysis.

[0118] In this embodiment, the first expression is preset to cos(δ0-θ0)≈1;

[0119] In this embodiment, the preset first optimization method is to add a low-pass filter to the front end of the droop coefficient. The block diagram of the optimized Pf droop control model is as follows. Figure 3 ;

[0120] In this embodiment, the second expression is preset to sΔθ(s)=ω B Δω g (s).

[0121] In this embodiment, the preset second optimization method involves adding a virtual damping control to the control structure. The optimized DC voltage matching control block diagram is shown below. Figure 5 ;

[0122] The beneficial effects of the above technical solution are as follows: by establishing small-signal models for Pf droop control, VSG control, and DC voltage matching control, constructing their initial transfer functions respectively, and optimizing the final transfer functions through preset optimization methods, the accuracy and applicability of the models are improved, providing a reliable basis for dynamic performance analysis and control parameter optimization.

[0123] Example 7:

[0124] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. The general form of the unified active-frequency transfer function model is as follows: Wherein, ΔP e (s) represents the disturbance component of active power in a unified form, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b is the reference frequency, s is the complex frequency variable in the preset analysis method, A is the inertia coefficient, B is the damping coefficient, C is the constant coefficient, and B′ is the molecular damping coefficient.

[0125] In this embodiment, the power angle characteristic coefficient is an important parameter used to describe the relationship between electrical power and power angle (usually the phase angle difference of grid voltage) in the power grid. In the power system, it directly reflects the power transmission capability and dynamic characteristics of equipment such as generators and inverters in the system.

[0126] The beneficial effects of the above technical solution are as follows: by establishing a general form of unified active-frequency transfer function model, key parameters such as inertia coefficient, damping coefficient, and power angle characteristic coefficient are comprehensively considered, and the common dynamic characteristics of Pf droop control, VSG control and DC voltage matching control are fully characterized, which improves the universality and adaptability of the model, provides a theoretical basis for system dynamic performance optimization and stability analysis, and simplifies the design of control strategy.

[0127] Example 8:

[0128] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical grid-connected control systems, determining a unified active-frequency transfer function model, including:

[0129] Obtain and analyze the system's performance requirements, and determine the model optimization objectives based on the analysis results;

[0130] Based on the model optimization objective and the preset objective-parameter data table, several key parameters to be optimized are determined.

[0131] Based on a pre-defined target-method database, the corresponding parameter optimization method is determined, and the key parameters to be optimized are optimized.

[0132] The performance of the optimized unified active-frequency transfer function model is verified based on the preset optimization analysis method, and the performance coefficients of the optimized unified active-frequency transfer function model are determined.

[0133] The optimization process continues until the performance coefficient of the optimized unified active-frequency transfer function model is greater than the preset performance coefficient.

[0134] The optimized unified active-frequency transfer function model is then determined as the final unified active-frequency transfer function model.

[0135] In this embodiment, the preset optimization analysis method includes: based on eigenvalue distribution: adjusting parameters to distribute the closed-loop poles in a suitable position in the left half-plane; based on frequency domain performance: adjusting parameters to make the amplitude frequency response of the transfer function meet the target (e.g., gain and phase margin); and numerical optimization method: using algorithms such as genetic algorithm, particle swarm optimization algorithm or gradient descent to optimize the dynamic performance of the transfer function.

[0136] In this embodiment, the preset performance coefficient is an evaluation criterion or indicator used to assess model performance during the optimization process. It defines the minimum performance requirements that the system must meet. Specifically, the preset performance coefficient is used to measure whether the optimized unified active-frequency transfer function model meets the design goals and system requirements, and is an important basis for determining whether the optimization process should end.

[0137] The beneficial effects of the above technical solution are: by setting optimization objectives and combining the objective-parameter data table and the objective-method database, the key parameters of the unified active-frequency transfer function model are optimized and the model performance is verified. The transfer function model can be iteratively optimized, significantly improving the dynamic performance and stability of the system, meeting the performance requirements of different network control strategies, and having high adaptability and practicality.

[0138] Example 9:

[0139] This invention provides a modeling method for characterizing the active-frequency response characteristics of typical network control systems. The model optimization objectives include: the model optimization objectives are related to frequency regulation capability, system damping, dynamic response speed, and / or system stability.

[0140] In this embodiment, frequency regulation capability refers to the system's ability to maintain grid frequency stability in the face of active power disturbances. By optimizing control parameters (such as droop coefficient or inertia coefficient), the system can quickly restore the frequency to the target value or stabilize it within a reasonable range when the load or generation changes. Optimization methods include: adjusting the active power-frequency droop coefficient to increase frequency response sensitivity; optimizing the power angle characteristic coefficient to enhance power-frequency coupling. For example, if the frequency regulation capability is weak, increasing the damping coefficient of the virtual synchronous generator (VSG) or adopting improved droop control can significantly improve the system's ability to regulate frequency disturbances and avoid large frequency deviations.

[0141] In this embodiment, system damping is used to suppress frequency oscillations and prevent the system from experiencing continuous oscillations or instability after a disturbance. Optimizing the damping coefficient can improve the system's oscillation attenuation capability. Optimization methods include increasing the virtual damping coefficient and optimizing the DC-side damping parameters in DC voltage matching control. For example, in an islanded microgrid, due to the small system inertia, low-frequency oscillations are prone to occur after a frequency disturbance. By optimizing the damping coefficient of the VSG, increasing B from 0.05 to 0.1 (relative value), the oscillation frequency amplitude is reduced by 50%, significantly improving system stability.

[0142] In this embodiment, dynamic response speed is improved by increasing the response speed, enabling the system to recover to steady state faster and enhancing dynamic performance. Optimization methods include: reducing the inertia coefficient (virtual inertia parameter) to increase frequency response speed; optimizing the droop coefficient to make the frequency-power coupling relationship more sensitive; and adjusting the controller bandwidth to improve control response speed. For example, in a grid with large-scale renewable energy integration, the frequency response speed is relatively slow. By optimizing the virtual inertia parameter, the inertia coefficient A is reduced from 0.1 to 0.05 (relative value), reducing the frequency recovery time from 5 seconds to 3 seconds without sacrificing stability.

[0143] In this embodiment, improving system stability ensures rapid recovery under both large and small-signal disturbances and prevents the system from entering an unstable state. Optimization methods include: increasing the inertia coefficient A to enhance the system's resistance to large disturbances; optimizing the power angle characteristic coefficient to ensure a reasonable power-frequency relationship; and increasing the damping coefficient to avoid low-frequency oscillations. For example, in weak grid scenarios, the system is prone to instability due to the low short-circuit ratio. By optimizing the inertia coefficients of droop control and the VSG, increasing A from 0.02 to 0.1, and improving the damping coefficient B, stable operation in weak grid environments is ultimately achieved.

[0144] The beneficial effects of the above technical solution are as follows: by clarifying the model optimization objectives, including improving frequency regulation capability, enhancing system damping, improving dynamic response speed, and improving system stability, key parameters are optimized in a targeted manner, which significantly improves the dynamic performance and anti-disturbance capability of the model. This method is applicable to different control strategies, enhances the adaptability of the model and the stability of power grid operation, and provides theoretical support for the optimization design of complex power grids.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modeling method for characterizing the active-frequency response characteristics of typical network control systems, characterized in that, include: Step 1: Obtain the key parameters of the circuit's preset parameter type, and at the same time, obtain the key parameters of the controller; Step 2: Determine the power angle characteristic coefficient and the angular frequency base value based on the key parameters of the circuit's preset parameter type and the key parameters of the controller's preset parameter type; Step 3: Construct transfer functions for preset types based on key parameters of the preset parameter type of the circuit, key parameters of the preset type of the controller, power angle characteristic coefficients, and angular frequency base values. This includes constructing transfer functions for Pf droop control, VSG control, and DC voltage matching control based on key parameters of the preset parameter type of the circuit, key parameters of the preset type of the controller, power characteristic coefficients, and angular frequency base values, respectively. Step 4: Construct a general form of unified active-frequency transfer function model based on the preset type of transfer function, and at the same time, determine the parameter table of network type. The construction of a general form of unified active-frequency transfer function model based on a preset type of transfer function includes: performing structural analysis on the transfer functions of Pf droop control, VSG control, and DC voltage matching control, and then determining the common transmission characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control based on the structural analysis results; and determining a general form of unified active-frequency transfer function model based on the common transmission characteristics of the transfer function models of Pf droop control, VSG control, and DC voltage matching control. The general form of the unified active-frequency transfer function model is as follows: Where, ΔP e (s) represents the disturbance component of active power in a unified form, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b is the reference frequency, s is the complex frequency variable in the preset analysis method, A is the inertia coefficient, B is the damping coefficient, C is the constant coefficient, and B′ is the molecular damping coefficient. Step 5: Determine the key values ​​in the unified active-frequency transfer function model based on the network type parameter table, and then solve the unified active-frequency transfer function model; the determination of the unified active-frequency transfer function model includes: Obtain and analyze the system's performance requirements, and determine the model optimization objectives based on the analysis results; Based on the model optimization objective and the preset objective-parameter data table, several key parameters to be optimized are determined. Based on a pre-defined target-method database, the corresponding parameter optimization method is determined, and the key parameters to be optimized are optimized. The performance of the optimized unified active-frequency transfer function model is verified based on the preset optimization analysis method, and the performance coefficients of the optimized unified active-frequency transfer function model are determined. The optimization process continues until the performance coefficient of the optimized unified active-frequency transfer function model is greater than the preset performance coefficient. The optimized unified active-frequency transfer function model is then determined as the final unified active-frequency transfer function model. The optimization objectives of the model are related to frequency regulation capability, system damping, dynamic response speed and / or system stability.

2. The modeling method for characterizing the active-frequency response characteristics of typical network control according to claim 1, characterized in that, Obtain key parameters of the circuit's preset parameter type, and simultaneously obtain key parameters of the controller, including: Key parameters of the first preset parameter type of the circuit are obtained based on the preset equipment technical documents; The key parameters of the second preset parameter type are determined based on the key parameters of the first preset parameter type of the circuit. The type of key parameters corresponding to each controller type is determined based on the preset controller type and the preset type-parameter database; Based on a preset parameter type-method database, the acquisition method for each type of key parameter is determined, thereby identifying several key parameters corresponding to each controller type.

3. The modeling method for characterizing the active-frequency response characteristics of typical network control according to claim 2, characterized in that, Controller types include: Pf droop control, VSG control, and DC voltage matching control.

4. The modeling method for characterizing the active-frequency response characteristics of typical network control according to claim 3, characterized in that, Based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, and the angular frequency base value, transfer functions for Pf droop control, VSG control, and DC voltage matching control are constructed, including: Based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset Pf droop characteristic expression, the small-signal model of Pf droop control is determined through a preset analysis method. Based on the preset first expression, the small-signal model of Pf droop control is organized to determine the initial function of Pf droop control. The initial function of Pf droop control is optimized based on the preset first optimization method, thereby determining the initial transfer function of Pf droop control: Wherein, ΔP1 e (s) represents the disturbance component of active power corresponding to the Pf droop control, Δω g (s) represents the disturbance component of the power grid frequency, k s ω is the characteristic coefficient of the work angle. b ω is the reference frequency, s is the complex frequency variable in the preset analysis method, and ω is the reference frequency. p K is the cutoff frequency corresponding to the preset first optimization method. p The gain is controlled proportionally. The small-signal model of VSG control is determined based on the key parameters of the circuit's preset parameter type, the key parameters of the controller's preset parameter type, the power characteristic coefficient, the angular frequency base value, and the preset mathematical model of VSG control. Based on the preset second expression, the small-signal model of VSG control is organized to determine the initial function of VSG control: Wherein, ΔP2 e (s) represents the disturbance component of the active power corresponding to VSG control, J is the virtual moment of inertia, and D is the virtual damping coefficient. Structural and dual analyses are performed on the converter and synchronous machine, and the corresponding matching relationship between the inverter DC voltage and the synchronous machine speed is determined based on the results of the structural and dual analyses. Based on the corresponding matching relationship between inverter DC voltage and synchronous machine speed, the comparative analysis quantity is changed from active power output to DC voltage output, and then the equations of the inverter DC side and AC side are determined by combining the preset circuit relationship. The initial function for DC voltage matching control is determined based on a pre-defined analysis method; The initial function of the voltage matching control is optimized based on the preset second optimization method, thereby determining the transfer function of the DC voltage matching control: Among them, ΔP3 e (s) represents the disturbance component of active power corresponding to DC voltage matching control, C dc K is the equivalent capacitance on the DC side. dc Kω represents the virtual DC damping control gain, and Kω is the damping coefficient.

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