Method and system for controlling converter under transient condition

Abstract

The invention provides a method and system for controlling a converter under a transient condition, and the method comprises the following steps: monitoring the voltage of a grid-connected point in real time, transmitting a voltage signal to a system fault detection module, comparing the voltage signal with a preset voltage threshold value, and generating a corresponding fault signal; adjusting the operation mode of the converter according to the fault signal; and when the system breaks down, the initial current instruction of the converter is dynamically adjusted. The adjustment process includes generating a trigger signal, generating a unit step signal, generating a first-order inertial response, and calculating an attenuation factor. By identifying the fault type and severity, the adaptive parameter adjustment module dynamically adjusts the current instruction according to the fault condition, thereby ensuring the accuracy and stability of the current instruction. According to the method, the response speed, the transient supporting capacity and the stability of the converter under the fault condition are remarkably improved, and the stability and the reliability of a power system can be enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of power system control, and particularly to a method and system for controlling a converter under transient conditions. Background Art

[0002] With the rapid development of power electronics technology, converters are increasingly widely used in power systems. Especially in the fields of renewable energy generation, smart grids, and industrial motor control, converters have become key equipment. A converter converts direct current into alternating current, or converts alternating current from one frequency and voltage to another frequency and voltage to achieve efficient energy transmission and control. However, during the operation of a power system, a converter needs to face various transient conditions, such as power grid faults, load mutations, and voltage sags, which pose severe challenges to the control performance of the converter.

[0003] Traditional converter control methods often have problems such as slow response speed, poor adaptability, insufficient transient support ability, and stability when dealing with power grid faults and other transient conditions. Specifically, when a fault occurs in a power system, such as a short circuit, overload, or overheating, the converter needs to respond within an extremely short time to maintain the stability of the system. This requires the converter control system to quickly and accurately detect the type and severity of the fault, and adjust the control strategy in real time according to the situation to ensure the accuracy and stability of the current command.

[0004] Currently, common converter control methods mainly include traditional methods based on proportional-integral (PI) control and advanced control methods based on modern control theory. The PI control method is widely used in engineering practice due to its simple structure and easy implementation. However, when dealing with complex transient conditions, the parameter adjustment of PI control depends on the system model, is sensitive to parameter changes, and is difficult to adapt to the rapid changes in a dynamic environment, resulting in limited control performance of the system.

[0005] Modern control theory introduces advanced control strategies such as predictive control, adaptive control, and robust control. These methods establish a mathematical model of the system and use optimization algorithms to adjust the control parameters online, having better dynamic performance and robustness. However, the implementation complexity of modern control methods is relatively high, and they have high requirements for computing resources and the accuracy of the system model, which limits their practical applications to a certain extent. Summary of the Invention

[0006] To solve the above problems in the prior art, the present invention proposes a method for controlling a converter under transient conditions, including the following steps:

[0007] Real-time monitor the voltage signal at the grid connection point;

[0008] Compare the voltage signal with a preset voltage threshold to generate a corresponding fault signal;

[0009] Adjust the operation mode of the converter according to the fault signal.

[0010] In the system fault operation mode, the initial current command of the converter is as shown in the following formula:

[0011]

[0012] The meanings of the parameters in the formula are as follows:

[0013] i d.ref.gf and i q.ref.gf respectively represent the reference currents of the d-axis and q-axis;

[0014] E q|0 : The no-load electromotive force of the synchronous motor before short circuit, which can be calculated according to the operation characteristics and typical parameters of the synchronous motor and then used in the converter;

[0015] u d|0 、u q|0 : The dq-axis components of the voltage at the front end of the short circuit after Park transformation, which can be calculated according to the operation characteristics and typical parameters of the synchronous motor and then used in the converter;

[0016] T′ d : The time constant of the excitation winding under the condition of stator short circuit, which can be selected with reference to the typical parameters of the synchronous motor and then used in the converter;

[0017] T a : The decay time constant of the DC component and the double-frequency AC component, which can be selected with reference to the typical parameters of the synchronous motor and then used in the converter;

[0018] x d 、x q : The direct-axis and quadrature-axis operational reactances of the stator, which can be selected with reference to the typical parameters of the synchronous motor and then used in the converter;

[0019] x′ d : The direct-axis transient reactance, which can be selected with reference to the typical parameters of the synchronous motor and then used in the converter;

[0020] t: Time.

[0021] The attenuation factors and in the formula are realized by an attenuation link, and the operation of the attenuation link includes the following steps:

[0022] Generate a trigger signal;

[0023] Generate a unit step signal;

[0024] Generate a first-order inertial response;

[0025] Subtract the number 1 from the first-order inertial response to obtain the final decay factor;

[0026] Among them, the time constant of the first-order inertial link for generating the decay factor of the d-axis current command is T′ d and T a , the time constant of the first-order inertial link for generating the decay factor of the q-axis current command is T a .

[0027] Dynamically adjust the initial current command of the converter according to the fault type and severity, which specifically includes the following steps:

[0028] Identify the fault type and severity;

[0029] Dynamically adjust the parameters in the current command expression according to the fault type and severity;

[0030] Dynamically adjust the current command according to the real-time monitored data;

[0031] Real-time monitor the output current and perform parameter optimization.

[0032] The adjusted current command is specifically as follows:

[0033] The adjusted d-axis current command expression:

[0034]

[0035] The adjusted q-axis current command expression:

[0036]

[0037] Among them: i d.ref.gf : the adjusted d-axis current command; i q.ref.gf : the adjusted q-axis current command; x d , x q : stator direct-axis and quadrature-axis operational reactances; x′ d : direct-axis transient reactance; t: time; T′ d : the time constant of the excitation winding under stator short circuit; T a : the decay time constant of the DC component and the double-frequency AC component; E q|0 ·(1 - k1·ɑ): the no-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient α and the adjustment coefficient k1; u q|0 ·(1 - k2·β): the q-axis component of the terminal voltage before short circuit is dynamically adjusted according to the fault type coefficient β and the adjustment coefficient k2; u d|0· (1 - k3·γ): The d-axis component of the short-circuit front-end voltage is dynamically adjusted according to the fault location coefficient γ and the adjustment coefficient k3.

[0038] The adjustment coefficient determines the specific values of the adjustment coefficients k1, k2, and k3 according to the fault severity coefficient α, the fault type coefficient β, and the fault location coefficient γ; the calculation formula of the adjustment coefficient is as follows:

[0039] k1 = k 1，0 · (1 - ɑ)

[0040] k2 = k 2，0 · (1 - β)

[0041] k3 = k 3，0 · (1 - γ)

[0042] Where k 1，0 , k 2，0 and k 3，0 are the initial adjustment coefficients.

[0043] Generating the corresponding fault signal further includes that when the voltage signal is higher than the set threshold, the system fault detection module determines that the system has no fault; when the voltage signal is lower than the set threshold, the system fault detection module determines that the system has a fault.

[0044] The fault types include short circuit, overload, or overheating.

[0045] After the system fault detection module determines that the system has a fault, it further includes: when the system has a fault, dynamically adjusting the initial current command of the converter according to the fault type and severity.

[0046] On the other hand, the present application also provides a system for controlling a converter under transient conditions, including:

[0047] A monitoring module for real-time monitoring of the voltage at the grid connection point;

[0048] A transmission module for transmitting the voltage signal to the system fault detection module;

[0049] A fault judgment module for comparing the voltage signal with a preset voltage threshold to generate a corresponding fault signal;

[0050] A mode adjustment module for adjusting the operating mode of the converter according to the fault signal;

[0051] An instruction adjustment module for dynamically adjusting the initial current command of the converter according to the fault type and severity when the system has a fault.

[0052] The initial current command is calculated according to the following formula:

[0053]

[0054] The meanings of the parameters in the formula are as follows:

[0055] i d.ref.gf and i q.ref.gf respectively represent the reference currents of the d-axis and q-axis;

[0056] E q|0 : The no-load electromotive force of the synchronous motor before short circuit;

[0057] u d|0 、u q|0 : The dq-axis components of the terminal voltage before short circuit after Park transformation;

[0058] T′ d : The time constant of the excitation winding under the condition of stator short circuit;

[0059] T a : The decay time constant of the DC component and the double-frequency AC component;

[0060] x d 、x q : The direct-axis and quadrature-axis operational reactances of the stator;

[0061] x′ d : The direct-axis transient reactance;

[0062] t: Time;

[0063] and decay factor.

[0064] It also includes a decay factor operation module for:

[0065] generating a trigger signal;

[0066] generating a unit step signal;

[0067] generating a first-order inertial response;

[0068] subtracting the number 1 from the first-order inertial response to obtain the final decay factor;

[0069] wherein, the time constant of the first-order inertial link of the decay factor for generating the d-axis current command is T′ d and T a and the time constant of the first-order inertial link of the decay factor for generating the q-axis current command is T a .

[0070] The instruction adjustment module is specifically used for:

[0071] identifying the fault type and severity;

[0072] Dynamically adjust the parameters in the current command expression according to the fault type and severity;

[0073] Dynamically adjust the current command according to the real-time monitored data;

[0074] Real-time monitor the output current and optimize the parameters.

[0075] The instruction adjustment module calculates the adjusted current command according to the following formula:

[0076] Adjusted d-axis current command expression:

[0077]

[0078] Adjusted q-axis current command expression:

[0079]

[0080] Where: i d.ref.gf : Adjusted d-axis current command; i q.ref.gf : Adjusted q-axis current command; x d 、x q : Stator direct-axis and quadrature-axis synchronous reactances; x′ d : Direct-axis transient reactance; t: Time; T′ d : Time constant of the field winding under stator short circuit; T a : Decay time constant of the DC component and the double-frequency AC component; E q|0 ·(1 - k1·α): The no-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient α and the adjustment coefficient k1; u q|0 ·(1 - k2·β): The q-axis component of the terminal voltage before short circuit is dynamically adjusted according to the fault type coefficient β and the adjustment coefficient k2; u d|0 ·(1 - k3·γ): The d-axis component of the terminal voltage before short circuit is dynamically adjusted according to the fault location coefficient γ and the adjustment coefficient k3.

[0081] The adjustment coefficients determine the specific values of the adjustment coefficients k1, k2, and k3 according to the fault severity coefficient ɑ, the fault type coefficient β, and the fault location coefficient γ; the calculation formula of the adjustment coefficients is as follows:

[0082] k1 = k 1，0 ·(1 - α)

[0083] k2 = k 2，0 ·(1 - β)

[0084] k3 = k 3，0 ·(1 - γ)

[0085] Where, k 1，0 、k 2，0 and k3，0 is the initial adjustment coefficient.

[0086] It further includes a fault judgment module for:

[0087] When the voltage signal is higher than the set threshold, the system fault detection module determines that the system has no fault; when the voltage signal is lower than the set threshold, the system fault detection module determines that the system has a fault.

[0088] On the other hand, the present application also provides an electronic device, including: at least one processor and a memory; the memory and the processor are connected by a bus;

[0089] The memory is used to store one or more programs;

[0090] When the one or more programs are executed by the at least one processor, a method for controlling a converter under transient conditions as described above is implemented.

[0091] On the other hand, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, a method for controlling a converter under transient conditions as described above is implemented.

[0092] Beneficial effects:

[0093] The present invention identifies the fault type and severity through a fault type identification module, and uses an adaptive parameter adjustment module to dynamically adjust the current command parameters according to these factors. When a fault occurs, the system adjusts according to real-time monitoring data, and the parameter feedback and optimization part optimizes in real time, enabling the system to quickly adapt to various complex fault situations. The accurate calculation of the attenuation factor ensures the accuracy of the current command, improves the response speed, transient support ability and stability of the converter under fault conditions. Through this design, the converter can accurately identify and make adjustments under different fault conditions such as short circuit, overload and over-temperature, significantly improving the reliability and stability of the system. Description of the Drawings

[0094] The drawings described herein are used to provide a further understanding of the present invention, form a part of the present application, but do not constitute an improper limitation of the present invention. In the drawings:

[0095] Figure 1 is the structural block diagram of the controller device of the present invention;

[0096] Figure 2 is the structural block diagram of the adaptive current control module of the present invention;

[0097] Figure 3 is the structural block diagram of the attenuation link of the present invention;

[0098] Figure 4 is the control method of the converter of the present invention;

[0099] Figure 5 is a schematic structural diagram of an electronic device of the present invention. Specific embodiments

[0100] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions are only used to explain the present invention, but not to limit the present invention.

[0101] The present invention provides a converter control device and method applicable to transient conditions. It includes detecting the grid connection point voltage through a detection device to determine whether a system fault occurs. When the grid connection point voltage is higher than the set threshold, the system is considered to be in a fault-free state; when the grid connection point voltage is lower than the set threshold, the system is considered to have a fault. According to the detection result, the operation mode of the converter is adjusted: when the system is fault-free, the converter operates in the normal mode; when the system has a fault, the converter switches to the fault operation mode. And in the fault operation mode, through the adaptive current control module, according to the type and severity of the fault, the parameters in the current command expression are dynamically adjusted, such as the no-load electromotive force before short circuit and the dq-axis components of the voltage at the front end of the short circuit, etc. Through these adjustments, the adaptive current control module can better adapt to the transient conditions in different fault situations, thereby improving the system response speed, transient support ability and stability, ensuring that the converter can effectively support the system voltage in various fault states and maintaining the stable operation of the power system. The specific embodiments are as follows:

[0102] Embodiment 1

[0103] 1. System architecture

[0104] As Figure 1 shown, the present system includes a grid connection point voltage detection device, a system fault detection module, a converter control module and an adaptive current control module.

[0105] 1.1 Grid connection point voltage detection device

[0106] The grid connection point voltage detection device is used to monitor the voltage of the grid connection point in real time and transmit the voltage signal to the system fault detection module. This device ensures the accuracy and real-time nature of the voltage signal through a high-precision sensor and a data acquisition system.

[0107] 1.2 System fault detection module

[0108] The system fault detection module receives the voltage signal from the grid connection point voltage detection device and compares it with a preset voltage threshold. When the voltage signal is higher than the set threshold, the module determines that the system is fault-free; when the voltage signal is lower than the set threshold, the module determines that the system has a fault. According to the judgment result, the module generates a corresponding fault signal.

[0109] 1.3 Converter control module

[0110] The converter control module adjusts the operating mode of the converter according to the fault signal generated by the system fault detection module. When the system is fault-free, the converter operates in the normal mode to ensure the stable transmission and conversion of electrical energy; when a fault occurs in the system, the converter switches to the fault operating mode to cope with system abnormalities, protect the equipment and maintain system stability.

[0111] 1.4 Adaptive current control module

[0112] The adaptive current control module dynamically adjusts the current command of the converter according to the fault type and severity when a fault occurs in the system. The module includes a fault type identification, parameter adjustment, and dynamic control algorithm part. By real-time monitoring and analyzing the system state, the adaptive current control module can flexibly adjust the control parameters, optimize the current output, and improve the stability and response speed of the system under fault conditions.

[0113] System working process

[0114] 1. Voltage monitoring: The grid connection point voltage detection device monitors the grid connection point voltage in real time and transmits the data to the system fault detection module.

[0115] 2. Fault judgment: The system fault detection module determines whether a fault has occurred in the system according to the received voltage signal and generates a corresponding fault signal.

[0116] 3. Mode switching: The converter control module adjusts the operating mode of the converter according to the fault signal. When the system is fault-free, the converter operates in the normal mode; when a fault occurs in the system, the converter switches to the fault operating mode.

[0117] 4. Current adjustment: In the case of a system fault, the adaptive current control module dynamically adjusts the current command according to the fault type and severity, optimizes the output current of the converter, and supports the stable operation of the system.

[0118] Through the above implementation methods, the present invention realizes the fast response and adaptive control of the converter under transient conditions, and improves the stability and reliability of the power system under fault conditions. This method has high practical value and can be widely applied to various converters.

[0119] 2. Fault detection and operation mode switching

[0120] The system fault detection module receives the grid connection point voltage signal and compares it with a preset voltage threshold. When the grid connection point voltage is lower than the set threshold, the module determines that a system fault has occurred and generates a corresponding fault signal. After receiving the fault signal, the converter control module immediately switches the operating mode of the converter from the normal mode to the fault operating mode.

[0121] In the fault operating mode, the converter will output current according to the specified synchronous motor stator current expression. This adjustment aims to simulate the transient behavior of the synchronous motor, thereby improving the converter's support ability for the system in the fault state and enhancing the stability and reliability of the system.

[0122] Specifically, after receiving the grid connection point voltage signal, the system fault detection module quickly and accurately determines the operating state of the system by comparing the signal with a preset voltage threshold. Once the voltage is detected to be lower than the threshold, the system fault detection module immediately generates a fault signal and transmits it to the converter control module. After receiving the fault signal, the converter control module quickly switches the operating mode to adjust the output current in the shortest time to meet the system requirements under fault conditions.

[0123] In this way, the converter can quickly respond and output current suitable for transient conditions when a system fault occurs, enhancing the system's dynamic reactive power support ability and preventing the occurrence of stability problems such as voltage collapse. This design not only improves the safety and reliability of the system but also enhances the adaptability of the converter in various complex power systems.

[0124] 3. Initial Current Command Generation

[0125] In the system fault operating mode, the initial current command of the converter is generated as shown in Formula (1) and Formula (2):

[0126] Formula (1):

[0127]

[0128] Formula (2):

[0129]

[0130] The meanings of the parameters in Formula (1) and Formula (2) are as follows:

[0131] E q|0 : The no-load electromotive force of the synchronous motor before the short circuit, which can be calculated according to the operating characteristics and typical parameters of the synchronous motor and then used in the converter;

[0132] u d|0 、u q|0: The d - axis and q - axis components of the short - circuit front - end voltage after Park transformation can be calculated according to the operating characteristics and typical parameters of the synchronous motor, and then used in the converter;

[0133] T′ d : The time constant of the field winding under stator short - circuit conditions can be selected with reference to the typical parameters of the synchronous motor, and then used in the converter;

[0134] T a : The decay time constant of the DC component and the double - frequency AC component can be selected with reference to the typical parameters of the synchronous motor, and then used in the converter;

[0135] x d 、x q : The direct - axis and quadrature - axis operational reactances of the stator can be selected with reference to the typical parameters of the synchronous motor, and then used in the converter;

[0136] x′ d : The direct - axis transient reactance can be selected with reference to the typical parameters of the synchronous motor, and then used in the converter;

[0137] t: Time

[0138] Through the above formula, the current command required by the converter can be accurately calculated when a fault occurs, ensuring that the converter can output current according to the stator current expression under the transient condition of the synchronous motor, thereby effectively supporting the system voltage.

[0139] Among them, i d.ref.gf and i q.ref.gf represent the reference currents of the d - axis and q - axis respectively. These current commands are based on the no - load electromotive force E q|0 of the synchronous motor before short - circuit, and the d - axis and q - axis components u d|0 、u q|0 obtained after Park transformation of the short - circuit front - end voltage. The time constant T′ d of the field winding under stator short - circuit conditions and the decay time constant T a of the DC component and the double - frequency AC component are then used to adjust the time - dynamic characteristics of the current command.

[0140] By using these parameters, the converter can simulate the behavior of the synchronous motor under transient conditions, provide accurate current output, and ensure that when a fault occurs in the system, it can quickly and accurately adjust the output current to support the stability and reliability of the system. This design not only improves the adaptability, transient support ability, and response speed of the converter, but also enhances its application value in complex power systems.

[0141] 4. Calculation of the attenuation factor

[0142] As shown in the appendix Figure 2As shown, the attenuation factors in Formula (1) and Formula (2) are composed of a system fault detection part, a step signal generator, a first-order inertia link, and an addition and subtraction operation part. The system fault detection part is used to generate a trigger signal to trigger the step signal generator to generate a unit step signal. The unit step signal generated by the step signal generator passes through the first-order inertia link to obtain a first-order inertia response. The addition and subtraction operation part is used to subtract the digital 1 from the first-order inertia response to obtain the final attenuation factor.

[0143] The expression of the converter output current command contains two attenuation factors, namely and In the process of generating the d-axis current command, both of the above two attenuation factors will be used; in the process of generating the q-axis current command, only will be used. For the attenuation factor used to generate the d-axis current command, the time constant of its first-order inertia link is set to T′ d and T a ; for the attenuation factor used to generate the q-axis current command, the time constant of its first-order inertia link is set to T a .

[0144] The specific calculation steps are as follows:

[0145] 1. Fault signal generation: After the system fault detection part detects a fault, it generates a trigger signal.

[0146] 2. Step signal generation: The trigger signal activates the step signal generator to generate a unit step signal.

[0147] 3. Inertia response generation: The unit step signal passes through the first-order inertia link to generate a first-order inertia response. The time constants T′ d and T a are used for the generation of the d-axis and q-axis current commands.

[0148] 4. Attenuation factor calculation: The addition and subtraction operation part subtracts the digital 1 from the first-order inertia response to obtain the final attenuation factor.

[0149] Through these steps, the attenuation factor can accurately reflect the transient response characteristics of the system. In the fault state, using these attenuation factors, the converter can generate accurate current commands to ensure that its output current can simulate the behavior of the synchronous motor under transient conditions, thereby effectively supporting the system voltage.

[0150] This design enhances the adaptability, transient support ability, and response speed of the converter under complex fault conditions through the accurate calculation of the attenuation factor, and improves the stability and reliability of the system.

[0151] Embodiment 2 Adaptive Current Control Module

[0152] As Figure 3 shown, the adaptive current control module includes a fault type identification module, an adaptive parameter adjustment module, a dynamic control algorithm module, and a parameter feedback and optimization section. This module realizes the adaptive adjustment of the converter current command through the following steps:

[0153] 1. Fault type identification

[0154] The fault type identification module identifies the type and severity of the fault by analyzing the fault signal. According to different types of faults, such as short circuit, load mutation, voltage sag, etc., the identification module can accurately judge the characteristics and influence range of the fault. In this way, the system can quickly and accurately respond to various fault situations, ensuring the effectiveness of current control.

[0155] 2. Adaptive parameter adjustment

[0156] According to the fault type and severity, the adaptive parameter adjustment module dynamically adjusts the parameters in the current command expression. The specific parameters to be adjusted include the no-load electromotive force E q|0 before short circuit, the dq-axis components u d|0 and u q|0 of the front-end voltage of the short circuit, etc. By dynamically adjusting these parameters, the converter can better adapt to the current fault conditions, and the response speed and stability of the converter can also be improved. This adjustment ensures that the converter can provide accurate and stable output current under fault conditions.

[0157] 3. Dynamic control algorithm module

[0158] The adaptive current control module adopts dynamic control algorithms to dynamically control the current command according to the real-time monitored data and fault type. These algorithms adjust the control coefficients according to the actual operating conditions of the power grid to ensure the stability and accuracy of the converter output current.

[0159] Specifically, in order to make the converter better adapt to different fault situations, it is necessary to dynamically adjust the parameters in the current command expression according to the fault type and severity. The specific parameters to be adjusted include the no-load electromotive force E q|0 before short circuit, the dq-axis components u d|0 and u q|0 of the front-end voltage of the short circuit, etc.

[0160] The adjustment process is specifically as follows:

[0161] 1. Fault type identification:

[0162] Use the fault type identification module to identify the fault type (such as short circuit, load mutation, voltage sag, etc.) and severity according to the monitored fault signal.

[0163] 2. Adaptive parameter adjustment:

[0164] Adjust the following parameters according to the identified fault type and severity:

[0165] No-load electromotive force E before short circuit q|0 : If the fault is severe, it may be necessary to reduce the electromotive force to reduce the current impact.

[0166] dq-axis components u of the voltage at the front end of the short circuit d|0 , u q|0 : Adjust the dq-axis voltage components according to the fault location and type to better control the current.

[0167] The specific expression of the adjusted current command is as follows:

[0168] Adjusted d-axis current command expression:

[0169]

[0170] Adjusted q-axis current command expression:

[0171]

[0172] The parameter adjustment instructions are as follows:

[0173] E q|0 ·(1 - k1·α): The no-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient α and the adjustment coefficient k1.

[0174] u q|0 ·(1 - k2·β): The q-axis component of the voltage at the front end of the short circuit is dynamically adjusted according to the fault type coefficient β and the adjustment coefficient k2.

[0175] u d|0 ·(1 - k3·γ): The d-axis component of the voltage at the front end of the short circuit is dynamically adjusted according to the fault location coefficient γ and the adjustment coefficient k3.

[0176] In addition, according to the fault type and severity, the calculation process of the specific control coefficient adjustment is as follows:

[0177] 1. Calculation of the fault severity coefficient α:

[0178] Real-time monitor the fluctuations of the system voltage and current, and judge the severity of the fault by calculating the amplitude and frequency of the fluctuations. Assuming the fluctuation amplitudes are △V and △I, the fault severity coefficient α can be expressed as:

[0179]

[0180] Among them, the value range of ɑ is [0, 1], where 0 represents no fault and 1 represents the most serious fault.

[0181] 2. Calculation of the fault type coefficient β and the fault location coefficient γ:

[0182] Based on the fault type and the location where the fault occurs, determine the fault type coefficient β and the fault location coefficient γ. Fault types include short circuit, overload, over-temperature, etc., and different fault types correspond to different coefficients β. Assume that for the short-circuit fault type, β = 0.8; for the overload fault type, β = 0.5; for the over-temperature fault type, β = 0.3. Fault locations include the low-voltage side of the transformer, the high-voltage side of the transformer, etc., and different locations correspond to different γ values. Assume that when the fault occurs on the low-voltage side of the transformer, γ = 0.9; when the fault occurs on the high-voltage side of the transformer, γ = 0.7.

[0183] 3. Calculation of the adjustment coefficients k1, k2, and k3:

[0184] Based on the fault severity coefficient α, the fault type coefficient β, and the fault location coefficient γ, determine the specific values of the adjustment coefficients k1, k2, and k3. The calculation formulas for the adjustment coefficients are as follows:

[0185] k1 = k 1，0 ·(1 - ɑ)

[0186] k2 = k 2.0 ·(1 - β)

[0187] k3 = k 3.0 ·(1 - γ)

[0188] Among them, k 1，0 , k 2，0 and k 3，0 are the initial adjustment coefficients, which are set according to actual experience values. Assume that k 1，0 = 0.9, k 2，0 = 0.8, k 3，0 = 0.7.

[0189] 4. Parameter feedback and optimization

[0190] The adaptive current control module monitors the output current of the converter in real time and compares it with the expected current command. Through parameter feedback and optimization, continuously adjust and optimize the parameters of the adaptive control algorithm to improve the stability and response speed of the converter. The parameter feedback and optimization process includes steps such as real-time data acquisition, error calculation, and parameter adjustment. In this way, the converter can maintain an optimal operating state in a dynamic environment.

[0191] Through the above embodiments, the adaptive current control module can provide fast and accurate current control under various fault conditions, ensuring the stable operation of the converter. This design enhances the adaptability and response speed of the converter, improving the stability and reliability of the power system.

[0192] Embodiment 3 System Fault Handling Process

[0193] When a system fault occurs, the fault detection module 2 generates a fault signal, triggering the converter control module to switch to the fault operation mode. The adaptive current control module dynamically adjusts the current command according to the fault type and severity. The system fault handling process is as Figure 2 shown and includes the following steps:

[0194] 1. The grid connection point voltage detection device continuously monitors the grid connection point voltage:

[0195] Through high-precision sensors, continuously monitor the voltage condition of the grid connection point to ensure the accuracy and timeliness of real-time data.

[0196] 2. The system fault detection module determines whether the voltage is lower than the set threshold:

[0197] The system fault detection module analyzes the collected voltage data and determines whether it is lower than the preset safety threshold.

[0198] 3. Generate a fault signal and switch to the fault operation mode:

[0199] If it is detected that the voltage is lower than the set threshold, the system fault detection module generates a fault signal.

[0200] The fault signal triggers the converter control module to switch to the fault operation mode, preparing to handle the fault situation.

[0201] 4. The adaptive current control module adjusts the current command parameters:

[0202] The adaptive current control module dynamically adjusts the initial current command parameters according to the fault type (such as short circuit, overload, overheating) and severity.

[0203] According to the fault severity coefficient α, fault type coefficient β, and location coefficient γ, determine the specific values of the adjustment coefficients k1, k2, and k3.

[0204] Furthermore, adjust the following parameters:

[0205] E q|0 ·(1 - k1·α): The no-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient α and the adjustment coefficient k1.

[0206] u q|0· (1 - k2·β): The q-axis component of the short-circuit front-end voltage is dynamically adjusted according to the fault type coefficient β and the adjustment coefficient k2.

[0207] u d|0 · (1 - k3·γ): The d-axis component of the short-circuit front-end voltage is dynamically adjusted according to the fault location coefficient γ and the adjustment coefficient k3.

[0208] 5. The converter outputs current according to the adjusted current command:

[0209] The converter outputs current according to the dynamically adjusted current command to support the grid connection point voltage and improve the stability of the system under fault conditions.

[0210] 6. Resume the normal operation mode after the fault is removed:

[0211] When the fault detection module confirms that the fault is removed, the converter control module will switch back to the normal operation mode to restore the normal working state of the system.

[0212] Method for controlling a converter under transient conditions in Embodiment 4

[0213] As shown in the Figure 4 accompanying drawings, the converter control method in the present invention includes the following specific steps and operating conditions:

[0214] Step 1: Real-time monitor the voltage of the grid connection point

[0215] 1. The voltage of the grid connection point is real-time monitored through a grid connection point voltage detection device.

[0216] 2. The monitored voltage signal is transmitted to the system fault detection module.

[0217] Step 2: Generate a fault signal

[0218] 1. The system fault detection module receives the voltage signal and compares it with a preset voltage threshold.

[0219] 2. When the voltage signal is higher than the set threshold, the system fault detection module determines that the system is fault-free.

[0220] 3. When the voltage signal is lower than the set threshold, the system fault detection module determines that the system has a fault and generates a corresponding fault signal.

[0221] Step 3: Adjust the converter operation mode

[0222] 1. The converter control module adjusts the operation mode of the converter according to the fault signal generated by the system fault detection module:

[0223] When the system is fault-free, the converter operates in the normal mode.

[0224] When a system failure occurs, the converter enters the fault operation mode.

[0225] Step Four: Dynamically adjust the initial current command of the converter

[0226] 1. When a system failure occurs, the adaptive current control module dynamically adjusts the initial current command of the converter according to the fault type and severity.

[0227] 2. In the system fault operation mode, the initial current command of the converter is as shown in Formula (1) and Formula (2):

[0228] Formula (1):

[0229]

[0230] Formula (2):

[0231]

[0232] Step Five: Calculate the attenuation factor

[0233] 1. Generate a trigger signal.

[0234] 2. Trigger the step signal generator to generate a unit step signal.

[0235] 3. The unit step signal passes through a first-order inertia link to generate a first-order inertia response.

[0236] 4. Subtract the number 1 from the first-order inertia response to obtain the final attenuation factor.

[0237] The time constant of the first-order inertia link for the attenuation factor used to generate the d-axis current command is T′ d and T a .

[0238] The time constant of the first-order inertia link for the attenuation factor used to generate the q-axis current command is T a .

[0239] Step Six: Dynamically adjust the initial current command according to the fault type and severity

[0240] 1. Identify the fault type and severity

[0241] The fault type identification module identifies the fault type (such as short circuit, overload or overheating) and severity by analyzing the fault signal.

[0242] 2. Dynamically adjust the parameters in the current command expression

[0243] According to the identified fault type and severity, the adaptive parameter adjustment module dynamically adjusts the parameters in the current command expression.

[0244] Adjusted d-axis current command expression:

[0245]

[0246] Adjusted q-axis current command expression:

[0247]

[0248] 3. Dynamically adjust the current command according to the real-time monitored data

[0249] The dynamic control algorithm dynamically adjusts the current command according to the real-time monitored data to ensure the accuracy and stability of the current command.

[0250] 4. Real-time monitor the output current and optimize the parameters

[0251] The parameter feedback and optimization part real-time monitors the output current of the converter and compares it with the expected current command.

[0252] According to the comparison result, continuously adjust and optimize the parameters of the adaptive control algorithm to improve the stability and response speed of the system.

[0253] Through the above implementation manners, the present invention realizes the fast response and adaptive control of the converter under transient conditions. By introducing real-time monitoring, dynamic adjustment and adaptive control mechanisms, the stability and reliability of the system under fault conditions are significantly improved. This method enables the converter to quickly respond under different fault conditions, provide reliable transient support, and avoid system instability caused by faults.

[0254] Embodiment 2

[0255] On the other hand, the present application also provides a system for controlling a converter under transient conditions, including:

[0256] A monitoring module for real-time monitoring the voltage of the grid connection point;

[0257] A fault judgment module for comparing the voltage signal with a preset voltage threshold to generate a corresponding fault signal;

[0258] A mode adjustment module for adjusting the operation mode of the converter according to the fault signal;

[0259] An instruction adjustment module for dynamically adjusting the initial current command of the converter according to the fault type and severity when a system fault occurs.

[0260] It further includes a transmission module for transmitting the voltage signal to the system fault detection module.

[0261] The initial current command is calculated according to the following formula:

[0262] Formula (1):

[0263]

[0264] Formula (2):

[0265]

[0266] The meanings of the parameters in Formula (1) and Formula (2) are as follows:

[0267] i d.ref.gf and i q.ref.gf respectively represent the reference currents of the d-axis and q-axis;

[0268] E q|0 : No-load electromotive force of the synchronous motor before short circuit;

[0269] u d|0 、u q|0 : dq-axis components of the terminal voltage before short circuit after Park transformation;

[0270] T′ d : Time constant of the excitation winding under the condition of stator short circuit;

[0271] T a : Decay time constant of the DC component and the double-frequency AC component;

[0272] x d 、x q : Stator direct-axis and quadrature-axis operational reactances;

[0273] x′ d : Direct-axis transient reactance;

[0274] t: Time;

[0275] and Decay factor.

[0276] It also includes a decay factor operation module for:

[0277] a. Generating a trigger signal;

[0278] b. Generating a unit step signal;

[0279] c. Generating a first-order inertia response;

[0280] d. Subtracting the number 1 from the first-order inertia response to obtain the final decay factor;

[0281] Among them, the time constants of the first-order inertia links of the decay factors used to generate the d-axis current command are T′ d and T a, the time constant of the first-order inertia link of the attenuation factor for generating the q-axis current command is T a .

[0282] The instruction adjustment module is specifically used for:

[0283] a. Identify the fault type and severity;

[0284] b. Dynamically adjust the parameters in the current command expression according to the fault type and severity;

[0285] c. Dynamically adjust the current command according to the real-time monitored data;

[0286] d. Real-time monitor the output current and optimize the parameters.

[0287] The instruction adjustment module calculates the adjusted current command according to the following formula:

[0288] Expression of the adjusted d-axis current command:

[0289]

[0290] Expression of the adjusted q-axis current command:

[0291]

[0292] Where:

[0293] E q|0 ·(1 - k1·α): The no-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient α and the adjustment coefficient k1;

[0294] u q|0 ·(1 - k2·β): The q-axis component of the terminal voltage before short circuit is dynamically adjusted according to the fault type coefficient β and the adjustment coefficient k2;

[0295] u d|0 ·(1 - k3·γ): The d-axis component of the terminal voltage before short circuit is dynamically adjusted according to the fault location coefficient γ and the adjustment coefficient k3.

[0296] The adjustment coefficient determines the specific values of the adjustment coefficients k1, k2, and k3 according to the fault severity coefficient ɑ, the fault type coefficient β, and the fault location coefficient γ; the calculation formula of the adjustment coefficient is as follows:

[0297] k1 = k 1，0 ·(1 - ɑ)

[0298] k2 = k 2.0 ·(1 - β)

[0299] k3 = k 3.0 ·(1 - γ)

[0300] Among them, k 1,0 , k 2，0 and k 3,0 are initial adjustment coefficients.

[0301] It further includes a fault judgment module for:

[0302] When the voltage signal is higher than the set threshold, the system fault detection module determines that the system has no fault; when the voltage signal is lower than the set threshold, the system fault detection module determines that the system has a fault.

[0303] As Figure 5 shown, the present invention further provides an electronic device, which may be a computer device, a single-chip microcomputer device, a smart mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor and the transceiver component are connected through a bus; the memory can be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, and the data can be called and / or modified when the instructions are executed.

[0304] The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor is the computing core and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a method for controlling a converter under transient conditions in the above embodiment.

[0305] Embodiment 4

[0306] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device-readable storage medium (Memory). The electronic device-readable storage medium is a memory device in an electronic device and is used to store programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and, of course, the extended storage medium supported by the electronic device. The storage medium provides a storage space, and this storage space stores the operating system of the terminal. Moreover, in this storage space, one or more instructions suitable for being loaded and executed by the processor are also stored. These instructions can be one or more executable programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. By the processor loading and executing one or more instructions stored in the storage medium, the steps of a method for controlling a converter under transient conditions in the above embodiments can be implemented.

[0307] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0308] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0309] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0310] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide for implementing the process Figure 1 one process or multiple processes and / or blocks Figure 1 steps of the functions specified in one block or multiple blocks.

[0311] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

[0312] The above is only a preferred embodiment of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics, and principles described in the scope of the present invention patent application are included within the scope of the present invention patent application.

Claims

1. A method for controlling a converter under transient conditions, comprising the following steps: Real-time monitor the voltage signal at the grid connection point; Compare the voltage signal with a preset voltage threshold to generate a corresponding fault signal; Adjust the operating mode of the converter according to the fault signal.

2. The method for controlling a converter under transient conditions according to claim 1, wherein: Under the system fault operating mode, the initial current command of the converter is as follows: The meanings of the parameters in the formula are as follows: i d.ref.gf and i q.ref.gf Let them represent the reference currents on the d-axis and q-axis respectively; E q|0 : Synchronous motor no-load electromotive force before short circuit; u d|0 and u q|0 : The d-axis and q-axis components of the short-circuit front-end voltage after Park transformation; T′ d : Time constant of the field winding in the case of stator short circuit; T a : Decay time constant of DC component and double-frequency AC component; x d and x q : direct-axis and quadrature-axis synchronous reactances of the stator; x′ d : Direct-axis transient reactance; t: time.

3. A method for controlling a converter under transient conditions according to claim 2, characterized in that: Attenuation factor in the formula and are implemented by an attenuation link, and the operation of the attenuation link includes the following steps: Generate a trigger signal; Generate a unit step signal; Generate a first-order inertial response; Subtract the number 1 from the first-order inertial response to obtain the final attenuation factor; Among them, the time constant of the first-order inertia link of the decay factor for generating the d-axis current command is T′ d and T a , and the time constant of the first-order inertia link of the decay factor for generating the q-axis current command is T a .

4. A method for controlling a converter under transient conditions as claimed in claim 1, characterized in that: Dynamically adjust the initial current command of the converter according to the fault type and severity, specifically including the following steps: Identify the fault type and severity; Dynamically adjust the parameters in the current command expression according to the fault type and severity; Dynamically adjust the current command according to the real-time monitored data; Real-time monitor the output current and perform parameter optimization.

5. A method for controlling a converter under transient conditions according to claim 4, characterized in that: The adjusted current command is specifically as follows: Adjusted d-axis current command expression: Adjusted q-axis current command expression: Where: i d.ref.gf : Adjusted d-axis current command; iq.ref.gf: Adjusted q-axis current command; x d 、x q : Stator direct-axis and quadrature-axis operational reactances; x′ d : Direct-axis transient reactance; t: Time; T′ d : Time constant of the field winding under stator short circuit; T a : Decay time constant of the DC component and double-frequency AC component; E q|0 ·(1 - k1·ɑ): No-load electromotive force before short circuit is dynamically adjusted according to the fault severity coefficient ɑ and the adjustment coefficient k1; u q|0 ·(1 - k2·β): q-axis component of the terminal voltage before short circuit; u d|0 ·(1 - k3·γ): d-axis component of the terminal voltage before short circuit.

6. A method for controlling a converter under transient conditions as claimed in claim 5, characterized in that: The adjustment coefficient determines the specific values of adjustment coefficients k1, k2, and k3 according to the fault severity coefficient α, fault type coefficient β, and fault location coefficient γ; the calculation formula of the adjustment coefficient is as follows: k1 = k 1,0 ·(1 - α) k2 = k 2.0 ·(1 - β) k3 = k 3.0 ·(1 - γ) where k 1，0 , k 2，0 and k 3,0 are initial adjustment coefficients.

7. A method for controlling a converter under transient conditions according to claim 1, characterized in that: Generate a corresponding fault signal, which further includes that when the voltage signal is higher than the set threshold, the system fault detection module determines that the system has no fault; when the voltage signal is lower than the set threshold, the system fault detection module determines that the system has a fault.

8. A method for controlling a converter under transient conditions according to claim 7, characterized in that: After the system fault detection module determines that the system has a fault, it further includes: when a fault occurs in the system, dynamically adjust the initial current command of the converter according to the fault type and severity.

9. A method for controlling a converter under transient conditions as claimed in claim 4, characterized in that: The fault type includes short circuit, overload, or overheating.

10. A system for controlling a converter under transient conditions, characterized in that, Includes: A monitoring module for real-time monitoring the voltage at the grid connection point; A fault judgment module for comparing the voltage signal with a preset voltage threshold to generate a corresponding fault signal; A mode adjustment module for adjusting the operating mode of the converter according to the fault signal; An instruction adjustment module for dynamically adjusting the initial current command of the converter according to the fault type and severity when a fault occurs in the system.

11. The system according to claim 10, wherein The initial current command is calculated according to the following formula: The meanings of the parameters in the formula are as follows: i d.ref.gf and i q.ref.gf represent the reference currents of the d-axis and q-axis, respectively; E q|0 : No-load electromotive force of synchronous motor before short circuit; u d|0 and u q|0 : The dq-axis components of the short-circuit front-end voltage after Park transformation; T′ d : Time constant of the field winding under the condition of stator short circuit; T a : Decay time constant of DC component and double-frequency AC component; x d and x q : direct-axis and quadrature-axis synchronous reactances of the stator; x′ d : Direct-axis transient reactance; t: time; and attenuation factor 12. The system according to claim 11, wherein It further includes an attenuation factor operation module for: Generate a trigger signal; Generate a unit step signal; Generate a first-order inertial response; Subtract the number 1 from the first-order inertial response to obtain the final attenuation factor; Among them, the time constant of the first-order inertia link of the decay factor for generating the d-axis current command is T′ d and T a , and the time constant of the first-order inertia link of the decay factor for generating the q-axis current command is T a .

13. The system according to claim 10, wherein The instruction adjustment module is specifically used for: Identify the fault type and severity; Dynamically adjust the parameters in the current command expression according to the fault type and severity; Dynamically adjust the current command according to the real-time monitored data; Real-time monitor the output current and perform parameter optimization.

14. The system according to claim 10, wherein The instruction adjustment module calculates the adjusted current command according to the following formula: Adjusted d-axis current command expression: Adjusted q-axis current command expression: Where: i d.ref.gf : Adjusted d-axis current command; i q.ref.gf : Adjusted q-axis current command; x d 、x q : Stator direct-axis and quadrature-axis synchronous reactances; x′ d : Direct-axis transient reactance; t: Time; T′ d : Time constant of the field winding under stator short circuit; T a : Decay time constant of the DC component and double-frequency AC component; E q|0 ·(1 - k1·α): No-load electromotive force before short circuit is dynamically adjusted according to the fault severity factor α and the adjustment factor k1; u q|0 ·(1 - k2·β): q-axis component of the terminal voltage before short circuit; u d|0 ·(1 - k3·γ): d-axis component of the terminal voltage before short circuit.

15. The system according to claim 14, wherein The adjustment coefficient determines the specific values of adjustment coefficients k1, k2, and k3 according to the fault severity coefficient ɑ, fault type coefficient β, and fault location coefficient γ; the calculation formula of the adjustment coefficient is as follows: k1 = k 1，0 ·(1 - ɑ) k2 = k 2，0 ·(1 - β) k3 = k 3，0 ·(1 - γ) where k 1，0 , k 2，0 and k 3，0 are initial adjustment coefficients.

16. The system according to claim 10, wherein It further includes a fault judgment module for: When the voltage signal is higher than the set threshold value, the system fault detection module determines that the system is fault-free; when the voltage signal is lower than the set threshold value, the system fault detection module determines that the system has a fault.

17. An electronic device, characterized in that, Comprising: At least one processor and a memory; The memory and the processor are connected by a bus; The memory is used for storing one or more programs; When the one or more programs are executed by the at least one processor, a method for controlling a converter under transient conditions as described in any one of claims 1 to 9 is implemented.

18. A readable storage medium, characterized in that, There is an execution program stored thereon, and when the execution program is executed, a method for controlling a converter under transient conditions as described in any one of claims 1 to 9 is implemented.

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