Frequency voltage response control method for network-forming converter

Abstract

The invention discloses a frequency and voltage response control method for a network construction type converter, which relates to the technical field of power electronics and comprises the following steps of: setting a frequency target value and a voltage target value; acquiring operation state data of the power grid and the converter through a sensor, and judging a power grid operation mode according to the operation state data; different dynamic target values are generated according to the power grid operation mode; constructing a frequency voltage prediction model by using support vector regression (SVR), inputting the dynamic target value into the frequency voltage prediction model, and outputting a predicted value vector; inputting the predicted value vector into a decoupling control model, and performing independent adjustment of frequency and voltage to obtain a control quantity; comparing the control quantity with a dynamic target value, and calculating frequency deviation and voltage deviation; according to the frequency deviation and the voltage deviation, the frequency and the voltage of the network-forming converter are adjusted; according to the method, the basic target value is set, so that a clear initial reference is provided for the operation of the network-forming converter.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a frequency and voltage response control method for a grid-connected converter. Background Art

[0002] As a representative of the new generation of power electronic converter technology, the grid-forming converter GFM plays an important role in modern power systems. With the continuous improvement of the penetration rate of new energy, the traditional power system dominated by synchronous generators SG is gradually transforming to a new energy power system with power electronic converters as the core. The grid-forming converter has become one of the key technologies to maintain the stability and reliability of the power system with its ability to independently establish grid voltage and frequency in a weak grid or even without a grid. In practical applications, the grid-forming converter adopts local control to achieve frequency and voltage response and regulation, and gradually replaces the role of synchronous generators in traditional power grids.

[0003] Existing grid-connected converter control technologies mainly rely on control strategies with fixed parameters. First, traditional control methods are difficult to adapt to the dynamic changes of different grid operation modes, resulting in decreased control accuracy in special scenarios such as weak grids or island operations. Second, existing technologies generally lack the ability to perceive and predict the operating status of the grid in real time, causing the converter's response to lag behind the dynamic changes of the grid, affecting system stability. In addition, for frequency and voltage regulation, traditional methods mostly use coupling control strategies, which make it difficult to achieve independent regulation of frequency and voltage, thereby limiting the flexibility of the control system. With the access of a high proportion of new energy to the power system, the uncertainty of the grid has increased significantly, and traditional control methods are increasingly unable to meet the current and future grid's needs for highly dynamic and highly adaptable control strategies. Summary of the invention

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

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

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a frequency and voltage response control method for a grid-connected converter, which comprises:

[0008] Set frequency target value and voltage target value;

[0009] Collect the operating status data of the power grid and the converter through sensors, and determine the power grid operation mode according to 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 the decoupling control model to perform independent regulation of frequency and voltage, and obtain the control quantity;

[0012] Compare the control quantity with the dynamic target value, 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 internal temperature of the converter through sensors;

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

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

[0017]

[0018] wherein, 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;

[0019] Set a threshold D1 for 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. The expression is:

[0024] X = X0 + k·D n+a·sin(b·D);

[0025] Among them, X is the well pattern 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;

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

[0027]

[0028] Among them, Y is the dynamic target value of the island, 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 solution of the frequency and voltage response control method of the grid-connected converter described in the present invention, wherein: the frequency and voltage prediction model is constructed by using support vector regression SVR, and the dynamic target value is input into the frequency and voltage prediction model to output the prediction value vector. The specific steps are as follows:

[0030] Set the selected dynamic target value to Z, where Z is a dynamic target value between X and Y;

[0031] Collect real-time operating status data and combine it with the dynamic target value to extract the characteristic vector φ, which is expressed as:

[0032] φ=[f,V,P,Q,I,T,D,Z];

[0033] Among them, φ is the input feature vector, Z is the dynamic target value;

[0034] Set the output prediction value vector to S;

[0035] The characteristic vector φ is input into the frequency and voltage prediction model to predict the future frequency and voltage values ​​of the power grid. The expression is:

[0036]

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

[0038] As a preferred solution of the frequency and voltage response control method of the grid-connected converter of the present invention, wherein: the predicted value vector is input into the decoupling control model to independently adjust the frequency and voltage to obtain the control quantity, and the specific steps are as follows:

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

[0040] Set the basic prediction value vector to S1 and the comprehensive adjustment amount to C;

[0041] The grid-connected converter output power is updated by comprehensive adjustment as the control quantity after frequency and voltage adjustment. The expression is:

[0042] M=E×(S-S1)+C

[0043] Among them, M is the control amount after rate and voltage adjustment, S1 is the basic frequency value target and the basic voltage target value, C is the active power adjustment amount and the reactive power adjustment amount, and E is the adjustment coefficient matrix.

[0044] As a preferred solution of the frequency and voltage response control method of the grid-type converter of the present invention, wherein: the control amount is compared with the dynamic target value, and the frequency deviation and voltage deviation are calculated. The specific steps are:

[0045] Set the control amount of the predicted frequency value and the predicted voltage value to M;

[0046] Compare the control amount and the dynamic target value, calculate the difference between the two as &, and get the degree of deviation between the control amount and the target value;

[0047] By taking the absolute value of N, the frequency and voltage deviations are calculated respectively, and the expressions are:

[0048] ΔM=|&|=|MZ|;

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

[0050] As a preferred solution of the frequency and voltage response control method of the grid-type converter of the present invention, wherein: the frequency and voltage of the grid-type converter are adjusted according to the frequency deviation and the voltage deviation, and the specific steps are:

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

[0052] According to the adjusted frequency and voltage, the active power and reactive power output of the grid-connected converter are updated.

[0053] The stable thresholds of frequency and voltage are set to ∈;

[0054] When ΔM≤∈, the adjustment ends;

[0055] When ΔM>∈, continue to adjust.

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

[0057] In a third aspect, 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, any step of the frequency and voltage response control method of a grid-type converter as described in the first aspect of the present invention is implemented.

[0058] The beneficial effects of the present invention are as follows: by setting a basic target value, the present invention provides a clear initial benchmark for the operation of a grid-connected converter, ensures that the converter frequency and voltage outputs are consistent with the grid standard, and improves the stability of system startup. By quantitatively evaluating the comprehensive disturbance index D and generating a dynamic target value, the present invention realizes accurate distinction and adaptive adjustment between the grid-connected mode and the island mode, significantly improving the robustness in a complex grid operation environment. Support vector regression (SVR) is used to predict future frequency and voltage values, so that the system has the ability to respond to grid changes in advance, optimizes the dynamic response performance, and realizes independent adjustment of frequency and voltage through a decoupling control model, avoiding the problem of coupling interference in traditional control and ensuring the accuracy and rapidity of adjustment. Finally, the frequency and voltage deviations are corrected in real time through a closed-loop feedback mechanism, dynamically approaching the target value, and further improving the system's response speed and control accuracy to disturbances. On the whole, the present invention solves the problems of inaccurate dynamic adjustment and delayed response in the prior art, and improves the adaptability and control performance of the grid-connected converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0060] Figure 1 This is a flow chart of the frequency and voltage response control method of the grid-connected converter in Example 1.

[0061] Figure 2 This is a schematic diagram of future frequency values ​​and voltages in Example 1. DETAILED DESCRIPTION

[0062] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0063] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present 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 term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

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

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

[0067] According to the rated frequency of the power grid standard, the basic frequency target value is set to F ′ ;

[0068] According to the rated voltage of the power grid standard, the basic voltage target value is set to V ′ ;

[0069] The present 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 fuzzy target values ​​or reliance on real-time calculation in traditional control methods, and can significantly improve the stability and calculation efficiency of the control process.

[0070] The process of setting the basic target value starts from the grid standard, ensuring the consistency of the converter output with the grid specification. Especially when the grid disturbance is large or in island mode, this consistency can provide guarantee for the safe operation of the grid.

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

[0072] The grid frequency, grid voltage, grid active power, grid reactive power, converter current and converter internal temperature are collected through sensors;

[0073] Calculate the deviations between the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and converter internal temperature 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 base frequency target value, V is the current grid voltage, V ′ is the base 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 converter internal temperature deviation;

[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] The present invention collects multi-dimensional status data including frequency, voltage, active power, reactive power, current and temperature through sensors to form a full range of monitoring of the operating status of the power grid and converter, which is significantly better than the method of only monitoring a single parameter (such as frequency or voltage) in the prior art.

[0088] The multi-parameter collection method enables the system to more accurately perceive the disturbance characteristics in a complex power grid environment, especially in island mode, which can help to promptly determine whether the power grid switches from grid-connected mode to island mode.

[0089] S3 generates different dynamic target values ​​according to the grid operation mode; uses support vector regression SVR to build a frequency and voltage prediction model, inputs the dynamic target value into the frequency and voltage prediction model to output a prediction value vector;

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

[0091] X=X0+k·D n +a·sin(b·D);

[0092] Among them, X is the well network dynamic target value (dynamic target value of grid voltage and grid frequency 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;

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

[0094]

[0095] Among them, 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 a dynamic target value between X and Y;

[0097] Collect real-time operating status data and combine it with the dynamic target value to extract the characteristic vector φ, which is expressed as:

[0098] φ=[f,V,P,Q,I,T,D,Z];

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

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

[0101] The support vector regression (SVR) prediction model combines the linear weight matrix W and the nonlinear kernel function to capture the complex relationship between input features, solving the problem that traditional linear models cannot adapt to the nonlinear dynamic changes of the power grid;

[0102] Set the output prediction value vector to S;

[0103] The characteristic vector φ is input into the frequency and voltage prediction model to predict the future frequency and voltage values ​​of the power grid. The expression is:

[0104]

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

[0106] The introduction of the comprehensive perturbation index realizes the quantitative evaluation of multi-dimensional parameters, solves the limitation 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 decoupling control model to independently adjust the frequency and voltage to obtain the control quantity;

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

[0109] Set the basic prediction value vector to S1 and the comprehensive adjustment amount to C;

[0110] The grid-connected converter output power is updated by comprehensive adjustment as the control quantity after frequency and voltage adjustment. The expression is:

[0111] M=E×(S-S1)+C

[0112] Among them, M is the control amount after rate and voltage adjustment, S1 is the basic frequency value target and basic voltage target value, C is the active power adjustment amount and reactive power adjustment amount, and E is the adjustment coefficient matrix;

[0113] The predicted value vector is input into the decoupling control model to independently adjust the frequency and voltage. This step uses the decoupling control model to separate the active power adjustment amount and the reactive power adjustment amount according to the frequency and voltage adjustment requirements. Compared with the defect of the mutual coupling of frequency and voltage regulation in the traditional control method, the present invention realizes the independent control of the two through the decoupling technology, and improves the adjustment 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. The present invention can effectively avoid this coupling problem by separating the adjustment amount through a decoupling control model, and significantly enhance the system's adaptability to complex disturbances.

[0115] The output power of the grid-connected converter is updated through the comprehensive adjustment amount C. The introduction of the comprehensive adjustment amount 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 compensation for active power and reactive power to ensure the rapid recovery of grid frequency and voltage.

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

[0117] S5 compares the control quantity with the dynamic target value, calculates the frequency deviation and the voltage deviation; adjusts the frequency and voltage of the grid-type converter according to the frequency deviation and the voltage deviation;

[0118] Set the control amount of the predicted frequency value and the predicted voltage value to M;

[0119] Compare the control amount and the dynamic target value, calculate the difference between the two as &, and get the degree of deviation between the control amount and the target value;

[0120] By taking the absolute value of N, the frequency and voltage deviations are calculated respectively, and the expressions are:

[0121] ΔM=|&|=|MZ|;

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

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

[0124] According to the adjusted frequency and voltage, the active power and reactive power output of the grid-connected converter are updated.

[0125] The stable thresholds of frequency and voltage are set to ∈;

[0126] By setting a stable threshold ∈, the present invention introduces a judgment condition for the end of regulation, avoiding excessive oscillation or repeated adjustment in the regulation process. The setting of the threshold makes the regulation process have a clear end standard, which improves the stability of system operation.

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

[0128] When ΔM≤∈, the adjustment ends;

[0129] When ΔM>∈, continue to adjust;

[0130] The present invention compares the control quantity with the dynamic target value, calculates the frequency and voltage deviations, and adjusts the output power of the grid-type converter based on the deviations, and has the following innovations and technical advantages:

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

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

[0133] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0134] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the frequency and voltage response control method of the grid-type converter proposed in the above embodiment is implemented; 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 (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read Only Memory, referred to as EPROM), programmable read-only memory (Programmable Red-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0135] In summary, the present invention provides a clear initial benchmark for the operation of the grid-connected converter by setting a basic target value, ensures that the converter frequency and voltage output are consistent with the grid standard, and improves the stability of the system startup; through the quantitative evaluation of the comprehensive disturbance index D and the generation of dynamic target values, it realizes the accurate distinction and adaptive adjustment of the grid-connected mode and the island mode, and significantly improves the robustness in a complex grid operation environment; uses support vector regression (SVR) to predict future frequency and voltage values, so that the system has the ability to respond to grid changes in advance, optimizes the dynamic response performance, and realizes independent adjustment of frequency and voltage through a decoupling control model, avoiding the problem of coupling interference in traditional control, and ensuring the accuracy and rapidity of the adjustment; finally, through a closed-loop feedback mechanism, the frequency and voltage deviations are corrected in real time, and the target value is dynamically approached, which further improves the system's response speed and control accuracy to disturbances. On the whole, the present invention solves the problems of inaccurate dynamic adjustment and delayed response in the prior art, and improves the adaptability and control performance of the grid-connected converter.

[0136] Example 2, referring to Table 1, is the second example 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-connected converter are provided.

[0137] In order to verify the effectiveness of the frequency and voltage response control method of the grid-connected converter, this experiment compared the regulation performance of the existing technology and the method of the present invention under complex grid disturbance conditions. The test device includes: a converter with a rated power of 100kW, simulated grid equipment (including grid-connected and island 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 operation state simulates complex working conditions by setting frequency disturbances, voltage fluctuations and load changes.

[0138] Specific implementation process:

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

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

[0141] and internal temperature, record the deviation between each parameter and the target value, and use the deviation value to pass the comprehensive disturbance index formula: The disturbance index D is calculated. When the D value is less than the set threshold D1(), the power grid is in grid-connected mode; when the D value is greater than D1, the power grid is in island mode.

[0142] Different formulas are used to generate dynamic target values ​​according to the grid mode. In the grid-connected mode, the dynamic target value is calculated according to 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 according to the formula: Y=X0+k·log(1+D)+c·√D(k=1.2,c=0.5).

[0143] The frequency and 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]; Z is the dynamic target value; the output prediction value vector is: The kernel function uses the radial basis kernel function (RBF) to predict the change value of frequency and voltage within the next 1 second.

[0144] The predicted value vector is input into the decoupling 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] The controlled quantity is compared with the dynamic target value, and the frequency and voltage deviations are calculated: 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, the frequency deviation, voltage deviation, dynamic response time, steady-state control accuracy and other data of the prior art and the method of the present invention are recorded respectively to evaluate the performance of the two methods.

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

[0147] Table 1 Test record

[0148]

[0149] From the data comparison in Table 1, it can be seen that the method of the present invention is significantly superior to the prior art in terms of frequency and voltage regulation capability. The specific analysis is as follows:

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

[0151] The method of the present invention shows obvious advantages in voltage deviation control. In the grid-connected mode, the maximum value and steady-state value of the voltage deviation are 2.1V and 0.8V respectively, while the corresponding values ​​of the prior art are 7.5V and 4.2V; in the island mode, the maximum value and steady-state value of the voltage deviation of the method of the present invention are 3.5V and 1.2V respectively, which are much lower than 12.4V and 6.8V of the prior art. This shows that through the decoupling control model, the present invention effectively reduces the coupling effect between frequency and voltage and improves the control accuracy.

[0152] The dynamic response time of the method of the present invention is 45ms in grid-connected mode and 55ms in island mode, which is significantly shortened compared with the prior art (120ms and 160ms, respectively); the steady-state recovery time is also shortened from 280ms and 350ms in the prior art to 120ms and 150ms, which shows that the present invention significantly improves the response speed and dynamic performance of the control system by introducing the 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 anti-disturbance capability. The variation ranges of D in the grid-connected mode and the island mode are 0.5 and 0.7, respectively, which are much smaller than 1.2 and 1.8 in the prior art. This indicates that the present invention can more effectively suppress disturbances and improve the stability of grid operation.

[0154] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A frequency and voltage response control method for a grid-connected converter, characterized in that: Including, Setting the frequency target value and the voltage target value; Collecting the operation status data of the power grid and the converter through sensors, and judging the operation mode of the power grid according to the operation status data; Generating different dynamic target values according to the operation mode of the power grid; Using Support Vector Regression (SVR) to construct a frequency-voltage prediction model, and 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 voltage to obtain a control quantity; Comparing the control quantity with the dynamic target value, calculating the frequency deviation and the voltage deviation; Adjusting the frequency and voltage of the grid-forming converter according to the frequency deviation and the voltage deviation.

2. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The specific steps for setting the frequency target value and the voltage target value are as follows. According to the rated frequency of the power grid standard, the basic frequency target value is set to F ′ ; According to the rated voltage of the power grid standard, the basic voltage target value is set to V ′ .

3. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The specific steps for collecting the operation status data of the power grid and the converter through sensors and judging the operation mode of the power grid according to the operation status data are as follows. Collecting the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and internal temperature of the converter through sensors; Calculating the deviations between the grid frequency, grid voltage, grid active power, grid reactive power, converter current, and internal temperature of the converter and the target values; Setting a comprehensive disturbance index D through the deviation values to quantify the disturbance degree of the power grid state, and the expression is: 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; Setting a threshold D1 of the comprehensive disturbance index to distinguish the operation mode of the power grid; When D < D1, the power grid is in the grid-connected mode; When D ≥ D1, the power grid is in the island mode.

4. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that The specific steps for generating different dynamic target values according to the operation mode of the power grid are as follows. In the grid-connected mode, calculating the grid-connected dynamic target value based on the comprehensive disturbance index, and the expression is: X=X0+k·D n +a·sin(b·D); where, 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 non-linear adjustment index, a is the sine amplitude coefficient, b is the sine frequency coefficient, and sin is the sine function; In the island mode, calculating and generating the island dynamic target value based on the comprehensive disturbance index, and the expression is: where, 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 non-linear adjustment term of the target value as the disturbance increases, and c is the square root adjustment amplitude coefficient.

5. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The specific steps for using Support Vector Regression (SVR) to construct a frequency-voltage prediction model and inputting the dynamic target values into the frequency-voltage prediction model to output a prediction value vector are as follows. Setting the selected dynamic target value as Z, where Z is one of the dynamic target values X and Y; Collecting the real-time operation status data and extracting the feature vector φ in combination with the dynamic target value, and the expression is: φ = [f, V, P, Q, I, T, D, Z]; where, φ is the input feature vector and Z is the dynamic target value; Setting the output prediction value vector as S; Inputting the feature vector φ into the frequency-voltage prediction model to predict the future frequency value and voltage value of the power grid, and the expression is: Among them, S is the output prediction value vector, i represents the index variable, W is the global weight matrix, B is the bias vector, α i is the Lagrange multiplier of the support vector, K(φ,φ i ) is the kernel function and N is the dimension of the input feature vector.

6. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The predicted value vector is input into the decoupling control model to independently adjust the frequency and voltage to obtain the control quantity. The specific steps are: The predicted value vector is input into the decoupling control model to separate the active power regulation amount and the reactive power regulation amount; Set the basic prediction value vector to S1 and the comprehensive adjustment amount to C; The grid-connected converter output power is updated by comprehensive adjustment as the control quantity after frequency and voltage adjustment. The expression is: M=E×(S-S1)+C Among them, M is the control amount after rate and voltage adjustment, S1 is the basic frequency value target and the basic voltage target value, C is the active power adjustment amount and the reactive power adjustment amount, and E is the adjustment coefficient matrix.

7. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The control amount is compared with the dynamic target value to calculate the frequency deviation and voltage deviation. The specific steps are: Set the control amount of the predicted frequency value and the predicted voltage value to M; Compare the control amount and the dynamic target value, calculate the difference between the two as &, and get the degree of deviation between the control amount and the target value; By taking the absolute value of N, the frequency and voltage deviations are calculated respectively, and the expressions are: ΔM=|&|=|MZ|; Among them, ΔM is the deviation vector, and |&| is the absolute value of the comparison result N.

8. The frequency and voltage response control method of a grid-connected converter according to claim 1, characterized in that: The frequency and voltage of the grid-type converter are adjusted according to the frequency deviation and the voltage deviation, and the specific steps are: Based on the frequency and voltage deviations, the frequency and voltage output of the grid-connected converter are adjusted respectively. According to the adjusted frequency and voltage, the active power and reactive power output of the grid-connected converter are updated. The stable thresholds of frequency and voltage are set to ∈; When ΔM≤∈, the adjustment ends; When ΔM>∈, continue to adjust.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the frequency and voltage response control method of the grid-connected converter according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the frequency and voltage response control method of a grid-connected converter according to any one of claims 1 to 7 are implemented.

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