A method for controlling frequency-voltage response of a grid-forming converter

Abstract

The application discloses a network-constructing type converter frequency-voltage response control method, relates to the technical field of power electronics, and comprises the following steps: setting a frequency target value and a voltage target value; collecting operation state data of a power grid and a converter through a sensor, and judging a power grid operation mode according to the operation state data; generating different dynamic target values according to the power grid operation mode; constructing a frequency-voltage prediction model by using support vector regression (SVR), inputting the dynamic target values into the frequency-voltage prediction model to output a prediction value vector; inputting the prediction value vector into a decoupling control model to independently adjust the frequency and the voltage, so as to obtain a control amount; comparing the control amount with the dynamic target values, and calculating a frequency deviation and a voltage deviation; and adjusting the frequency and the voltage of the network-constructing type converter according to the frequency deviation and the voltage deviation.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a frequency voltage response control method for grid-type converters. Background Technology

[0002] As a representative of the new generation of power electronic converter technology, the grid-connected converter (GFM) plays an important role in modern power systems. With the continuous increase in the penetration rate of new energy sources, the traditional power system dominated by synchronous generators (SG) is gradually transforming into a new energy power system with power electronic converters as its core. The grid-connected converter, with its ability to autonomously establish grid voltage and frequency in weak grid or even gridless conditions, has become one of the key technologies for maintaining the stability and reliability of power systems. In practical applications, the grid-connected converter adopts local control to realize frequency and voltage response and regulation, and is gradually replacing the role of synchronous generators in traditional power grids.

[0003] Existing grid-connected converter control technologies mainly rely on fixed-parameter control strategies. First, traditional control methods struggle to adapt to the dynamic changes in different grid operating modes, leading to decreased control accuracy in special scenarios such as weak grids or islanded operation. Second, existing technologies generally lack real-time sensing and prediction capabilities for grid operating status, causing the converter's response to lag behind grid dynamic changes and affecting system stability. Furthermore, for frequency and voltage regulation, traditional methods often employ coupled control strategies, making it difficult to achieve independent frequency and voltage regulation, thus limiting the flexibility of the control system. With the integration of a high proportion of new energy sources into the power system, grid uncertainty has increased significantly, making it increasingly difficult for traditional control methods to meet the current and future grid requirements for highly dynamic and adaptable control strategies. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a frequency and voltage response control method for grid-connected converters to solve the problem that traditional control methods are difficult to adapt to the dynamic changes of different power grid operation modes, resulting in a decrease in control accuracy in special scenarios such as weak power grids or islanded operation.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a frequency voltage response control method for a grid-type converter, comprising,

[0008] Set the target values ​​for frequency and voltage;

[0009] The power grid and converter operating status data are collected by sensors, and the power grid operating mode is determined based on the operating status data.

[0010] Generate different dynamic target values according to the grid operation mode; use Support Vector Regression (SVR) to construct a frequency-voltage prediction model, and input the dynamic target values into the frequency-voltage prediction model to output a prediction value vector;

[0011] Input the prediction value vector into a decoupling control model to perform independent regulation of frequency and voltage, and obtain control quantities;

[0012] Compare the control quantities with the dynamic target values, calculate the frequency deviation and voltage deviation; adjust the frequency and voltage of the grid-forming converter according to the frequency deviation and voltage deviation.

[0013] As a preferred solution of the frequency-voltage response control method for the grid-forming converter described in the present invention, wherein: collecting the operation state data of the grid and the converter through sensors, and judging the grid operation mode according to the operation state data, the specific steps are as follows,

[0014] Collect the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and converter internal temperature through sensors;

[0015] Calculate the deviations between the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and converter internal temperature and the target values;

[0016] Set a comprehensive disturbance index D through the deviation values to quantify the disturbance degree of the grid state, and the expression is:

[0017]

[0018] where, Δf is the grid frequency deviation, ΔV is the grid voltage deviation, ΔP is the grid active power deviation, ΔQ is the grid reactive power deviation, ΔI is the converter current deviation, and ΔT is the converter internal temperature deviation;

[0019] Set a threshold D1 of the comprehensive disturbance index to distinguish the grid operation mode;

[0020] When D < D1, the grid is in the grid-connected mode;

[0021] When D ≥ D1, the grid is in the island mode.

[0022] As a preferred solution of the frequency-voltage response control method for the grid-forming converter described in the present invention, wherein: generating different dynamic target values according to the grid operation mode, the specific steps are as follows,

[0023] In the grid-connected mode, calculate the grid-connected dynamic target value based on the comprehensive disturbance index, and the expression is:

[0024] X = X0 + k·D n+a·sin(b·D);

[0025] Where X is the dynamic target value of the well network, X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, n is the nonlinear adjustment index, a is the sinusoidal amplitude coefficient, b is the sinusoidal frequency coefficient, and sin is the sine function.

[0026] In islanded mode, the dynamic target value for the island is calculated and generated based on the comprehensive disturbance index, and the expression is:

[0027]

[0028] Where Y is the islanded dynamic target value, X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, log(1+D) is the nonlinear adjustment term of the target value as the disturbance increases, and c is the square root adjustment amplitude coefficient.

[0029] As a preferred embodiment of the frequency voltage response control method for a grid-type converter described in this invention, the steps of constructing a frequency voltage prediction model using support vector regression (SVR), inputting the dynamic target value into the frequency voltage prediction model, and outputting a predicted value vector are as follows:

[0030] Set the selected dynamic target value to Z, where Z is one of the dynamic target values ​​of X and Y;

[0031] The feature vector φ is extracted by combining real-time operational status data with dynamic target values, and the expression is:

[0032] φ = [f,V,P,Q,I,T,D,Z];

[0033] Where φ is the input feature vector and Z is the dynamic target value;

[0034] Let the output predicted value vector be S;

[0035] Inputting the feature vector φ into the frequency-voltage prediction model predicts the future frequency and voltage values ​​of the power grid, as expressed in the following expression:

[0036]

[0037] Where S is the output predicted value vector, i represents the index variable, W is the global weight matrix, B is the bias vector, and α i It is the Lagrange multiplier of the support vectors, K(φ,φ i ) is the kernel function, and N is the dimension of the input feature vector.

[0038] As a preferred embodiment of the frequency-voltage response control method for the grid-type converter described in this invention, the specific steps of inputting the predicted value vector into the decoupled control model to independently adjust the frequency and voltage to obtain the control quantity are as follows:

[0039] The predicted value vector is input into the decoupled control model to separate the active power regulation and reactive power regulation.

[0040] Let the basic predicted value vector be S1, and the comprehensive adjustment amount be C;

[0041] The output power of the grid-type converter is updated by a comprehensive adjustment, which serves as the control quantity after frequency and voltage regulation. The expression is as follows:

[0042] M = E × (S - S1) + C

[0043] Where M is the control quantity after rate and voltage regulation, S1 is the target value of the base frequency and the target value of the base voltage, C is the active power regulation quantity and the reactive power regulation quantity, and E is the regulation coefficient matrix.

[0044] In a preferred embodiment of the frequency-voltage response control method for a grid-type converter described in this invention, the step of comparing the control quantity with the dynamic target value and calculating the frequency deviation and voltage deviation specifically includes the following steps:

[0045] Set the control values ​​for the predicted frequency and predicted voltage to M;

[0046] By comparing the control input and the dynamic target value, the difference between the two is calculated as &, which gives the degree of deviation between the control input and the target value;

[0047] By taking the absolute value of N, the deviations in frequency and voltage are calculated separately, and the expressions are as follows:

[0048] ΔM = |&| = |MZ|;

[0049] Where ΔM is the deviation vector, and |&| is the absolute value of the comparison result N.

[0050] In a preferred embodiment of the frequency-voltage response control method for the grid-type converter described in this invention, the specific steps for adjusting the frequency and voltage of the grid-type converter based on frequency and voltage deviations are as follows:

[0051] Based on the frequency and voltage deviations, the frequency and voltage outputs of the grid-type converter are adjusted respectively.

[0052] Based on the adjusted frequency and voltage, update the active and reactive power outputs of the grid-type converter.

[0053] The set stability thresholds for frequency and voltage are ∈;

[0054] If ΔM≤∈, then the adjustment ends;

[0055] If ΔM>∈, then continue adjusting.

[0056] In a second aspect, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, wherein when the computer program is executed by the processor, it implements any step of the frequency voltage response control method for a grid-type converter as described in the first aspect of the present invention.

[0057] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the frequency voltage response control method for a grid-type converter as described in the first aspect of the present invention.

[0058] The beneficial effects of this invention are as follows: By setting a basic target value, this invention provides a clear initial benchmark for the operation of grid-connected converters, ensuring that the converter's frequency and voltage output are consistent with the grid standard, thus improving the stability of system startup. Through the quantitative evaluation of the comprehensive disturbance index D and the generation of dynamic target values, it achieves accurate differentiation and adaptive adjustment between grid-connected and islanded modes, significantly improving robustness in complex grid operating environments. By using support vector regression (SVR) to predict future frequency and voltage values, the system has the ability to respond to grid changes in advance, optimizing dynamic response performance. By using a decoupled control model to achieve independent adjustment of frequency and voltage, it avoids the problem of coupling interference in traditional control, ensuring the accuracy and speed of adjustment. Finally, through a closed-loop feedback mechanism, it corrects frequency and voltage deviations in real time, dynamically approximating the target value, further improving the system's response speed and control accuracy to disturbances. Overall, this invention solves the problems of inaccurate dynamic adjustment and lag response in the prior art, improving the adaptability and control performance of grid-connected converters. Attached Figure Description

[0059] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 This is a flowchart of the frequency voltage response control method for the grid-type converter in Example 1.

[0061] Figure 2 This is a schematic diagram of the future frequency and voltage values ​​in Example 1. Detailed Implementation

[0062] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0063] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0064] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0065] Example 1, referring to Figure 1 and Figure 2 This is the first embodiment of the present invention, which provides a frequency voltage response control method for a grid-type converter, comprising the following steps:

[0066] S1 sets the target frequency and voltage values;

[0067] The target value of the fundamental frequency is set to F according to the rated frequency of the power grid standard. ′ ;

[0068] The base voltage target value is set to V based on the rated voltage of the power grid standard. ′ ;

[0069] This invention clarifies the starting point and direction of frequency and voltage regulation by setting basic target values ​​(F' and V'). This concept avoids the drawbacks of vague target values ​​or reliance on real-time calculation in traditional control methods, and can significantly improve the stability and computational efficiency of the control process.

[0070] The process of setting basic target values ​​starts from the power grid standards, ensuring that the converter output is consistent with the power grid specifications. This consistency can provide a guarantee for the safe operation of the power grid, especially in the case of large power grid disturbances or islanding mode.

[0071] S2 collects operating status data of the power grid and converter through sensors, and determines the power grid operating mode based on the operating status data;

[0072] The system collects data on grid frequency, grid voltage, grid active power, grid reactive power, converter current, and converter internal temperature using sensors.

[0073] Calculate the deviations between the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and the internal temperature of the converter and their target values; the expressions are as follows:

[0074] ΔF = F - F ′ ;

[0075] ΔV = V - V ′ ;

[0076] ΔP = P - P ′ ;

[0077] ΔQ = Q - Q ′ ;

[0078] ΔI = I - I ′ ;

[0079] ΔT = T - T ′ ;

[0080] Where, F is the current grid frequency, F ′ is the basic frequency target value, V is the current grid voltage, V ′ is the basic voltage target value, P is the current grid active power, P ′ is the rated grid active power, Q is the current grid reactive power, Q ′ is the rated grid reactive power, I is the current converter current, I ′ is the rated reference current of the converter, T is the current internal temperature of the converter, T ′ is the reference temperature of the converter;

[0081] Based on the deviation values, set the comprehensive disturbance index D to quantify the disturbance degree of the grid state. The expression is as follows:

[0082]

[0083] Where, Δf is the grid frequency deviation, ΔV is the grid voltage deviation, ΔP is the grid active power deviation, ΔQ is the grid reactive power deviation, ΔI is the converter current deviation, and ΔT is the internal temperature deviation of the converter;

[0084] Set the threshold D1 of the comprehensive disturbance index to distinguish the grid operation mode;

[0085] When D < D1, the grid is in the grid-connected mode;

[0086] When D ≥ D1, the grid is in the island mode;

[0087] This invention collects multi-dimensional status data, including frequency, voltage, active power, reactive power, current, and temperature, using sensors to form a comprehensive monitoring system for the operating status of the power grid and converter. This is significantly superior to existing methods that only monitor a single parameter (such as frequency or voltage).

[0088] The multi-parameter acquisition method enables the system to more accurately perceive the disturbance characteristics in complex power grid environments, especially in islanded mode, which can help determine in a timely manner whether the power grid has switched from grid-connected mode to islanded mode.

[0089] S3 generates different dynamic target values ​​based on the power grid operation mode; it uses support vector regression (SVR) to construct a frequency voltage prediction model, inputs the dynamic target values ​​into the frequency voltage prediction model, and outputs a predicted value vector.

[0090] In the well network model, the dynamic target value of the well network is calculated based on the comprehensive disturbance index, and the expression is:

[0091] X = X0 + k·D n +a·sin(b·D);

[0092] Where X is the dynamic target value of the well network (dynamic target value of grid voltage and target value of grid frequency), X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, n is the nonlinear adjustment index, a is the sinusoidal amplitude coefficient, b is the sinusoidal frequency coefficient, and sin is the sinusoidal function.

[0093] In islanded mode, the dynamic target value for the island is calculated and generated based on the comprehensive disturbance index, and the expression is:

[0094]

[0095] Where Y is the island dynamic target value (island voltage dynamic target value and island frequency target value), X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, log(1+D) is the nonlinear adjustment term of the target value as the disturbance increases, and c is the square root adjustment amplitude coefficient.

[0096] Set the selected dynamic target value to Z, where Z is one of the dynamic target values ​​of X and Y;

[0097] The feature vector φ is extracted by combining real-time operational status data with dynamic target values, and the expression is:

[0098] φ = [f,V,P,Q,I,T,D,Z];

[0099] Where φ is the input feature vector, and Z is the dynamic target value (grid-connected mode, select grid-connected dynamic target value X; islanded mode, select islanded dynamic target value Y);

[0100] The setting of the feature vector φ covers the key parameters of power grid operation and can comprehensively reflect the status information of the power grid and converter;

[0101] The Support Vector Regression (SVR) prediction model combines a linear weight matrix W and a nonlinear kernel function to capture the complex relationships between input features, solving the problem that traditional linear models cannot adapt to the nonlinear dynamic changes of the power grid.

[0102] Let the output predicted value vector be S;

[0103] Inputting the feature vector φ into the frequency-voltage prediction model predicts the future frequency and voltage values ​​of the power grid, as expressed in the following expression:

[0104]

[0105] Where S is the output predicted value vector (predicted voltage and predicted frequency values), i represents the index variable, W is the global weight matrix (corresponding to the linear relationship of the eigenvectors), B is the bias vector (used to adjust the offset of the prediction result), and α i It is the Lagrange multiplier of the support vectors, K(φ,φ i ) is the kernel function (used to capture the non-linear relationship between input feature vectors), and N is the dimension of the input feature vectors;

[0106] The introduction of the comprehensive disturbance index enables the quantitative evaluation of multi-dimensional parameters, overcomes the limitations of single parameter adjustment in traditional methods, and enhances the robustness and applicability of the system.

[0107] S4 inputs the predicted value vector into the decoupled control model to independently adjust the frequency and voltage, thereby obtaining the control quantity;

[0108] The predicted value vector is input into the decoupled control model to separate the active power regulation and reactive power regulation.

[0109] Let the basic predicted value vector be S1, and the comprehensive adjustment amount be C;

[0110] The output power of the grid-type converter is updated by a comprehensive adjustment, which serves as the control quantity after frequency and voltage regulation. The expression is as follows:

[0111] M = E × (S - S1) + C

[0112] Where M is the control quantity after rate and voltage regulation, S1 is the target value of the base frequency and the target value of the base voltage, C is the active power regulation quantity and the reactive power regulation quantity, and E is the regulation coefficient matrix.

[0113] The predicted value vector is input into the decoupled control model for independent frequency and voltage regulation. This step, through the decoupled control model, separates the active power regulation and reactive power regulation quantities according to the frequency and voltage regulation requirements. Compared to the shortcomings of traditional control methods where frequency and voltage regulation are coupled, this invention achieves independent control of both through decoupling technology, improving regulation accuracy and response speed.

[0114] In traditional power grid control, frequency changes affect voltage, and voltage adjustments may in turn affect frequency, making it difficult for the control system to respond quickly and accurately. This invention separates the regulation quantity by decoupling the control model, which can effectively avoid this coupling problem and significantly enhance the system's adaptability to complex disturbances.

[0115] The output power of the grid-type converter is updated by the comprehensive adjustment quantity C. The introduction of the comprehensive adjustment quantity C enables the output power of the converter to dynamically adapt to the current disturbance conditions. Especially when the grid disturbance is large, C can quickly provide active and reactive power compensation to ensure the rapid recovery of grid frequency and voltage.

[0116] In traditional methods, the adjustment of converter output power is usually based on a single parameter (such as frequency), which is difficult to fully reflect the actual operating state of the power grid. This invention, by combining the comprehensive adjustment amount C with the results of the prediction model, can comprehensively consider the frequency, voltage and power requirements of the power grid, and significantly improve the adaptability and accuracy of the adjustment.

[0117] S5 compares the control input with the dynamic target value and calculates the frequency deviation and voltage deviation; it then adjusts the frequency and voltage of the grid-type converter based on the frequency deviation and voltage deviation.

[0118] Set the control values ​​for the predicted frequency and predicted voltage to M;

[0119] By comparing the control input and the dynamic target value, the difference between the two is calculated as &, which gives the degree of deviation between the control input and the target value;

[0120] By taking the absolute value of N, the deviations in frequency and voltage are calculated separately, and the expressions are as follows:

[0121] ΔM = |&| = |MZ|;

[0122] Where ΔM is the deviation vector (frequency deviation and voltage deviation), and |&| is the absolute value of the comparison result N;

[0123] Based on the frequency and voltage deviations, the frequency and voltage outputs of the grid-type converter are adjusted respectively.

[0124] Based on the adjusted frequency and voltage, update the active and reactive power outputs of the grid-type converter.

[0125] The set stability thresholds for frequency and voltage are ∈;

[0126] By setting a stability threshold ∈, this invention introduces a condition for determining the end of adjustment, avoiding excessive oscillations or repeated adjustments during the adjustment process. The setting of this threshold provides a clear end standard for the adjustment process, thereby improving the stability of system operation.

[0127] In traditional methods, the adjustment process lacks a clear end criterion, which may lead to over-adjustment or under-adjustment, affecting the stability of the system. This invention solves this problem by introducing a threshold ∈, while ensuring that the adjustment accuracy meets actual needs.

[0128] If ΔM≤∈, then the adjustment ends;

[0129] If ΔM>∈, then continue adjusting;

[0130] This invention calculates frequency and voltage deviations by comparing control quantities with dynamic target values, and adjusts the output power of the grid-type converter based on these deviations, offering the following innovations and technical advantages:

[0131] The introduction of dynamic target values ​​enables the adjustment target to adapt to the grid condition in real time; the definition and absolute value calculation of the deviation vector provide a clear basis for the direction and intensity of adjustment; independent adjustment of frequency and voltage avoids the problem of adjustment coupling in traditional methods.

[0132] This embodiment also provides a computer device applicable to the frequency voltage response control method for grid-type converters, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the frequency voltage response control method for grid-type converters as proposed in the above embodiment.

[0133] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0134] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the frequency voltage response control method for a grid-type converter as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0135] In summary, this invention provides a clear initial benchmark for the operation of grid-connected converters by setting basic target values, ensuring that the converter's frequency and voltage output are consistent with grid standards, thus improving the stability of system startup. Through quantitative evaluation of the comprehensive disturbance index D and generation of dynamic target values, it achieves accurate differentiation and adaptive adjustment between grid-connected and islanded modes, significantly improving robustness in complex grid operating environments. By using support vector regression (SVR) to predict future frequency and voltage values, the system has the ability to respond to grid changes in advance, optimizing dynamic response performance. Independent adjustment of frequency and voltage is achieved through a decoupled control model, avoiding the coupling interference problem in traditional control and ensuring the accuracy and speed of adjustment. Finally, a closed-loop feedback mechanism is used to correct frequency and voltage deviations in real time, dynamically approximating the target values, further improving the system's response speed and control accuracy to disturbances. Overall, this invention solves the problems of inaccurate dynamic adjustment and lag in existing technologies, improving the adaptability and control performance of grid-connected converters.

[0136] Example 2, referring to Table 1, is the second embodiment of the present invention. To further verify the technical solution of the present invention, experimental simulation data of the frequency voltage response control method of the grid converter are given.

[0137] To verify the effectiveness of the frequency and voltage response control method for grid-connected converters, this experiment compared the regulation performance of existing technologies and the method of this invention under complex grid disturbance conditions. The test setup included: a converter with a rated power of 100kW, a grid simulation device (including grid-connected and islanded mode switching functions), a data acquisition system (sensors collect grid frequency, voltage, active power, reactive power, converter current, and internal temperature), and a control processing system. During the experiment, the grid operating status was simulated by setting frequency disturbances, voltage fluctuations, and load changes to simulate complex operating conditions.

[0138] Specific implementation process:

[0139] According to power grid standards, the target value for the base frequency is set at 50Hz and the target value for the base voltage is set at 380V, which are used as the initial reference target values ​​for grid-connected and islanded modes, respectively.

[0140] Real-time data collection of grid frequency, voltage, active power, reactive power, and converter current is achieved through sensors.

[0141] Record the deviations between each parameter and the target value, including the internal temperature, and use the deviation values ​​to apply the comprehensive disturbance index formula: Calculate the disturbance index D. When the value of D is less than the set threshold D1(), the power grid is in grid-connected mode; when the value of D is greater than D1, the power grid is in islanded mode.

[0142] Depending on the power grid mode, different formulas are used to generate dynamic target values. In grid-connected mode, the dynamic target value is calculated using the formula: X = X0 + k·D n +a·sin(b·D)(k=0.8,n=2,a=0.1,b=1.5); In island mode, the dynamic target value is calculated using the formula: Y=X0+k·log(1+D)+c·√D(k=1.2,c=0.5).

[0143] A frequency-voltage prediction model is constructed using the Support Vector Regression (SVR) method. The input feature vector is: φ = [f, V, P, Q, I, T, D, Z], where Z is the dynamic target value. The output predicted value vector is: The kernel function used is the radial basis function (RBF), which predicts the changes in frequency and voltage within the next second.

[0144] The predicted value vector is input into the decoupled control model to separate the active power regulation and reactive power regulation of frequency and voltage. The control quantity calculation formula is: M=E×(S-S1)+C, where E is the regulation coefficient matrix and S1 is the basic target value vector.

[0145] Compare the control quantity with the dynamic target value and calculate the frequency and voltage deviation: ΔM = |&| = |MZ|. If the deviation ΔM exceeds the set threshold ∈ (0.02), continue to adjust until the deviation meets the requirements. Under different disturbance conditions, record the frequency deviation, voltage deviation, dynamic response time and steady-state control accuracy of the existing technology and the method of this invention to evaluate the performance of the two methods.

[0146] The details are shown in Table 1 below:

[0147] Table 1 Experimental Record Sheet

[0148]

[0149] As can be seen from the data comparison in Table 1, the method of the present invention is significantly superior to the prior art in terms of frequency and voltage regulation capability, as detailed below:

[0150] In grid-connected mode, the maximum frequency deviation of the method of the present invention is 0.03Hz and the steady-state deviation is 0.01Hz, which is significantly lower than the 0.15Hz and 0.08Hz of the prior art. In islanded mode, the maximum frequency deviation and steady-state deviation of the present invention are 0.05Hz and 0.02Hz, respectively, which are also much lower than the 0.25Hz and 0.12Hz of the prior art. This shows that the present invention significantly improves the accuracy and response capability of frequency regulation by generating dynamic target values ​​and introducing SVR prediction models.

[0151] The method of this invention exhibits significant advantages in voltage deviation control. In grid-connected mode, the maximum and steady-state voltage deviations are 2.1V and 0.8V, respectively, while the corresponding values ​​in the prior art are 7.5V and 4.2V. In islanded mode, the maximum and steady-state voltage deviations of the method of this invention are 3.5V and 1.2V, respectively, which are much lower than the 12.4V and 6.8V of the prior art. This indicates that by decoupling the control model, this invention effectively reduces the coupling effect between frequency and voltage, thereby improving control accuracy.

[0152] The dynamic response time of the method of the present invention is 45ms in grid-connected mode and 55ms in islanded mode, which is significantly reduced compared with the prior art (120ms and 160ms respectively); the steady-state recovery time is also reduced from 280ms and 350ms in the prior art to 120ms and 150ms. This shows that the present invention significantly improves the response speed and dynamic performance of the control system by introducing an SVR prediction model and dynamic target value generation.

[0153] The variation range of the comprehensive disturbance index D is an important indicator for measuring the system's ability to resist disturbances. The variation range of D in the grid-connected and islanded modes of the present invention is 0.5 and 0.7, respectively, which is much smaller than the 1.2 and 1.8 of the prior art. This shows that the present invention can more effectively suppress disturbances and improve the stability of power grid operation.

[0154] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling frequency-voltage response of a meshed network converter, characterized in that: Comprising, set the frequency target value and voltage target value; Collecting the operating state data of the power grid and the converter through the sensor, judging the power grid operating mode according to the operating state data, the specific steps are, Collecting the power grid frequency, power grid voltage, power grid active power, power grid reactive power, converter current and converter internal temperature through the sensor; Calculate the deviation between the power grid frequency F, power grid voltage V, power grid active power P, power grid reactive power Q, converter current I and converter internal temperature T and the target value; Set the comprehensive disturbance index D through the deviation value, quantify the disturbance degree of the power grid state, the expression is: Wherein, ΔF is the power grid frequency deviation, ΔV is the power grid voltage deviation, ΔP is the power grid active power deviation, ΔQ is the power grid reactive power deviation, ΔI is the converter current deviation, and ΔT is the converter internal temperature deviation; Set the threshold value D1 of the comprehensive disturbance index to distinguish the power grid operating mode; When D < D1, the power grid is in grid-connected mode; When D ≥ D1, the power grid is in island mode; Generating different dynamic target values according to the power grid operating mode, the specific steps are, In the grid-connected mode, the grid-connected dynamic target value is calculated based on the comprehensive disturbance index, the expression is: X = X0+ k - D n + a - sin(b - D); Wherein, X is the grid-connected dynamic target value, X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, n is the nonlinear adjustment index, a is the sine amplitude coefficient, b is the sine frequency coefficient, and sin is the sine function; In the island mode, the island dynamic target value is calculated based on the comprehensive disturbance index, the expression is: Wherein, Y is the island dynamic target value, X0 is the basic target value, D is the comprehensive disturbance index, k is the adjustment coefficient, log(1+D) is the nonlinear adjustment term of the target value with the disturbance increasing, and c is the square root adjustment amplitude coefficient; The frequency voltage prediction model is constructed by using support vector regression SVR, the dynamic target value is input into the frequency voltage prediction model to output the prediction value vector, and the specific steps are, Set the selected dynamic target value as Z, wherein Z is one of X and Y; Collecting real-time operating state data combined with dynamic target value to extract the feature vector φ, the expression is: φ = [F, V, P, Q, I, T, D, Z]; Wherein, φ is the input feature vector, and Z is the dynamic target value; Set the output prediction value vector as S; Input the input feature vector φ into the frequency voltage prediction model to predict the future frequency value and voltage value of the power grid, the expression is: where S is the output predicted value vector, i denotes the index variable, W is the global weight matrix, B is the bias vector, a i is the Lagrange multiplier of support vector, K(φ,φ i ) is the kernel function, N is the dimension of input feature vector, and φ represents the input feature vector; Input the prediction value vector into the decoupling control model to independently adjust the frequency and voltage, and obtain the control amount; Compare the control amount with the dynamic target value to calculate the frequency deviation and voltage deviation; Adjust the frequency and voltage of the grid type converter according to the frequency deviation and voltage deviation.

2. The network configuration type converter frequency-voltage response control method according to claim 1, characterized by: The specific steps of setting the frequency target value and voltage target value are, The base frequency target value is set to F according to the rated frequency of the power grid ′ The base voltage target value is set to V according to the rated voltage of the power grid ′ .

3. The networked converter frequency-voltage response control method of claim 1, wherein: The specific steps of inputting the prediction value vector into the decoupling control model to independently adjust the frequency and voltage, and obtaining the control amount are, Input the prediction value vector into the decoupling control model to separate the active power regulation amount and the reactive power regulation amount; Set the basic prediction value vector as S1, and the comprehensive regulation amount as C; The output power of the grid-forming converter is updated by comprehensively adjusting the amount, which is a control amount after frequency and voltage adjustment, and the expression is: M=E×(S-S1)+C Wherein, M is the control amount after frequency and voltage adjustment, S1 is the basic frequency value target or the basic voltage target value, C is the active power adjustment amount or the reactive power adjustment amount, and E is the adjustment coefficient matrix.

4. The network-configured converter frequency-voltage response control method of claim 1, wherein: The control amount is compared with the dynamic target value, and the frequency deviation and the voltage deviation are calculated, and the specific steps are: The control amount of the predicted frequency value or the predicted voltage value is set as M; The control amount and the dynamic target value are compared, and the difference between the two is calculated as N, to obtain the deviation degree between the control amount and the target value; The absolute value of N is taken to calculate the frequency deviation and the voltage deviation, and the expression is: ΔM=|N|=|M-Z|; Wherein, ΔM is the deviation vector, and |N| is the absolute value of the comparison result N.

5. The networked converter frequency-voltage response control method of claim 1, wherein: The frequency and the voltage of the grid-forming converter are adjusted according to the frequency deviation and the voltage deviation, and the specific steps are: Based on the frequency and voltage deviation, the frequency and voltage output of the grid-forming converter are adjusted respectively, According to the adjusted frequency and voltage, the active power and the reactive power output of the grid-forming converter are updated, The stable threshold of the frequency or the voltage is set as ∈; When ΔM≤∈, the adjustment is ended; When ΔM>∈, the adjustment is continued. 6.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is characterized in that: The processor executes the computer program to realize the steps of the grid-forming converter frequency voltage response control method in any one of claims 1-5.

7. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program is executed by the processor to realize the steps of the grid-forming converter frequency voltage response control method in any one of claims 1-5.

Images