Intermittent arc fault simulation model and device for power distribution network

Abstract

The invention provides a power distribution network intermittent arc fault simulation model and device. The model comprises a single-phase earth fault block; the single-phase grounding fault block comprises a grounding switch and a control subsystem. The grounding switch is connected with the control subsystem and is used for changing the state according to an arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch; and the control subsystem is used for determining the operation of the grounding switch according to the received fault current and terminal voltage and generating an arc fault trigger signal so as to realize arc ignition and extinguishing logic. According to the intermittent arc fault simulation model and device for the power distribution network provided by the invention, the dynamic characteristics of the intermittent arc fault are accurately simulated, and the reliability of a simulation result is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular, to a simulation model and device for intermittent arc faults in a distribution network. Background Art

[0002] The neutral point of a medium voltage (MV) distribution network has various operating forms, including isolation, compensation, low-resistance or high-resistance grounding. Different grounding methods will bring differences to the electrical characteristics of the entire distribution system in a fault state. In this network, when a single-phase ground fault (SPGF) occurs, the current shows capacitive characteristics. This is because the impedance of the fault loop is mostly composed of cable capacitance. Since the cable line length in the MV distribution network usually does not exceed several kilometers, the impedance of the SPGF loop can reach thousands of ohms, so the fault current value is relatively low. Intermittent arc faults often occur in cable lines. When a fault occurs, the arc will ignite and then extinguish itself at irregular time intervals, generating high current spikes within a short time interval, posing a threat to the stable operation of the power system.

[0003] The current intermittent arc simulation technology for grounding faults has defects and cannot vividly present and depict the intermittent characteristics of the arc. This is extremely disadvantageous for researchers to analyze fault conditions and develop corresponding protection strategies, because accurate simulation is an important means to understand the fault mechanism and test the effectiveness of protection schemes. The deficiencies in existing simulation and modeling have hindered the advancement of related research and practical work. Summary of the Invention

[0004] In view of the problems in the prior art, the embodiments of the present application provide a simulation model and device for intermittent arc faults in a distribution network, which can at least partially solve the problems existing in the prior art.

[0005] In a first aspect, the present application provides a simulation model for intermittent arc faults in a distribution network, including: a single-phase ground fault block;

[0006] The single-phase ground fault block includes a grounding switch and a control subsystem;

[0007] The grounding switch is connected to the control subsystem and is used to change its state according to the arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch;

[0008] The control subsystem is used to determine the operation of the grounding switch and generate an arc fault trigger signal according to the received fault current and terminal voltage, so as to implement the arc ignition and extinguishing logic.

[0009] Further, the single-phase ground fault block further includes:

[0010] Configuration module, used to set parameters of the grounding switch, grounding resistance, start time and end time of a fault, and initial voltage phase of the fault;

[0011] Arc parameter module, used to define arc faults and their types;

[0012] Interruption module, used to generate interruption signals according to interruption types to simulate intermittent faults.

[0013] Furthermore, the control subsystem includes:

[0014] Initial phase control module, used to generate an initial phase delay signal according to the initial voltage phase of the fault;

[0015] Arc fault module, used to generate an arc control signal according to the fault current, the terminal voltage, and the arc fault and its type;

[0016] Logical AND module, used to generate the arc fault trigger signal according to the fault signal, the initial phase delay signal, the arc control signal, and the interruption signal.

[0017] Furthermore, the arc fault module includes:

[0018] Waiting time sub-module, used to record the arc ignition time and set the time constant for high-frequency component attenuation;

[0019] Signal filtering sub-module, used to extract the fundamental frequency component of the fault current.

[0020] Furthermore, the arc fault module further includes:

[0021] Zero-crossing sub-module, used to control arc extinction based on the zero-crossing detection signal of the fault current.

[0022] Furthermore, the control subsystem further includes:

[0023] Fault limitation module, used to set the limitation on the number of arc faults and the time delay between two consecutive faults, and stop fault triggering when the set number is exceeded.

[0024] Furthermore, the fault limitation module includes:

[0025] Count limiter sub-module, used to calculate the number of faults that have occurred and disable the arc fault trigger signal when the set number is reached;

[0026] Time delay sub-module, used to delay the arc fault trigger signal according to a preset time delay value.

[0027] Further, the ignition voltage change mode of the arc parameter module supports at least one of a linear mode, a pulse generator mode, a step mode, and a step with ramp mode.

[0028] Further, the interruption module includes;

[0029] A white noise generation sub-module for generating the interruption signal according to random white noise;

[0030] A pulse generator sub-module for generating the interruption signal according to a set period and pulse width;

[0031] A time-dependent pulse sub-module for defining a single-signal switching time sequence for interruption control.

[0032] In a second aspect, the present application provides a simulation device for intermittent arc faults in a distribution network, including the simulation model for intermittent arc faults in a distribution network as described in any of the above embodiments, for simulating intermittent arc faults in the distribution network, so as to perform fault characteristic analysis and fault detection.

[0033] The present application provides a simulation model and device for intermittent arc faults in a distribution network. The model includes: a single-phase grounding fault block; the single-phase grounding fault block includes a grounding switch and a control subsystem; the grounding switch is connected to the control subsystem and is used to change its state according to the arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch; the control subsystem is used to determine the operation of the grounding switch and generate an arc fault trigger signal according to the received fault current and terminal voltage, so as to implement the logic of arc ignition and extinction. The simulation model and device for intermittent arc faults in a distribution network provided by the present application accurately simulate the dynamic characteristics of intermittent arc faults and ensure the reliability of the simulation results. Among them, the control subsystem supports a variety of trigger logics and parameter configurations and can be flexibly adjusted according to different research requirements; by simplifying the modeling of the grounding switch, the computational complexity is significantly reduced and the simulation efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a schematic structural diagram of a simulation model for intermittent arc faults in a distribution network provided by an embodiment of the present application;

[0036] Figure 2It is a schematic structural diagram of a control subsystem provided by an embodiment of the present application;

[0037] Figure 3 It is a partial schematic structural diagram of an arc fault module provided by an embodiment of the present application;

[0038] Figure 4 It is a schematic structural diagram of a zero-crossing sub-module provided by an embodiment of the present application;

[0039] Figure 5 It is a schematic structural diagram of an interruption module provided by an embodiment of the present application;

[0040] Figure 6 It is an external schematic diagram of a single-phase grounding fault block provided by an embodiment of the present application;

[0041] Figure 7 It is a schematic structural diagram of an arc fault module provided by an embodiment of the present application;

[0042] Figure 8 It is a schematic structural diagram of a waiting time sub-module provided by an embodiment of the present application;

[0043] Figure 9 It is a schematic structural diagram of a signal filtering sub-module provided by an embodiment of the present application;

[0044] Figure 10 It is a schematic structural diagram of a distribution network test scheme provided by an embodiment of the present application. Detailed implementation manners

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer and more understandable, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but not to limit the present application. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily.

[0046] Figure 1 It is a schematic structural diagram of a distribution network intermittent arc fault simulation model provided by an embodiment of the present application. As Figure 1 shown, the distribution network intermittent arc fault simulation model provided by the present application includes: a single-phase grounding fault block;

[0047] The single-phase grounding fault block includes a grounding switch and a control subsystem;

[0048] The grounding switch is connected to the control subsystem and is used to change its state according to the arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch;

[0049] The control subsystem is used to determine the operation of the grounding switch based on the received fault current and terminal voltage and generate an arc fault trigger signal to implement the arc ignition and extinction logic.

[0050] Specifically, the single-phase grounding fault block (SPGF) is a core component of the distribution network intermittent arc fault simulation model, which is used to reproduce the occurrence and recovery process of intermittent arc faults, provide a real simulation environment, and simulate the physical characteristics of single-phase grounding faults and their impact on the distribution network. This block includes two key components: a grounding switch and a control subsystem.

[0051] The grounding switch Ideal Switch is modeled based on an ideal switch, has fast response capabilities, high simulation accuracy, does not need to consider the complex non-linear characteristics of actual switches, simplifies the modeling complexity, and improves the simulation efficiency. As a switching element for the fault state, according to the trigger signal of the control subsystem, the grounding switch switches to the on or off state to implement the arc ignition and extinction logic. This switch instantaneously changes its state according to the control signal on port g.

[0052] The control subsystem Control receives the fault current and terminal voltage and generates an arc fault trigger signal for driving the grounding switch. Based on the received fault current and terminal voltage data, it judges the arc trigger conditions, implements the arc ignition and extinction logic, simulates the dynamic changes of intermittent faults, and realizes the precise control of arc faults. The control subsystem periodically triggers the on-off of the grounding switch through a preset logical or random control mechanism to simulate the intermittent characteristics of the arc. This dynamic behavior can be used to test the response ability of the distribution network to intermittent arc faults.

[0053] Using an ideal switch and real-time control logic, the distribution network intermittent arc fault simulation model can accurately simulate the dynamic characteristics of intermittent arc faults and ensure the reliability of simulation results. The control subsystem supports multiple trigger logics and parameter configurations and can be flexibly adjusted according to different research requirements. By simplifying the modeling of the grounding switch, the computational complexity is significantly reduced, and the simulation efficiency is improved.

[0054] In one embodiment, the appearance of the single-phase grounding fault block is as Figure 6 shown, with single-phase and three-phase designs.

[0055] In one embodiment, the single-phase grounding fault block further includes:

[0056] A configuration module for setting parameters of the grounding switch, grounding resistance, start time and end time of the fault, and initial voltage phase of the fault;

[0057] An arc parameter module for defining arc faults and their types;

[0058] An interrupt module, which is used to generate an interrupt signal according to the interrupt type to simulate intermittent faults.

[0059] Specifically, the configuration module, the arc parameter module, and the interrupt module are parameter setting tabs. The configuration module is used to define the basic parameters and operating conditions related to ground faults. Its main functions include allowing users to define the dynamic response characteristics of the grounding switch, including the switch switching time, the on-resistance value, etc.; configuring the value of the grounding resistance to simulate different types of grounding conditions (such as low-resistance grounding or high-resistance grounding); defining the trigger time and extinguishing time of the fault, supporting representation in absolute time (such as seconds) or relative time (such as the number of system cycles); defining the initial voltage phase at the time of fault occurrence, which is used to simulate the phase influence at the time of arc triggering.

[0060] The arc parameter module defines the characteristics and types of arc faults to achieve accurate simulation of intermittent faults. The selection of arc types is divided into a static arc model and a dynamic arc model. The static arc model has fixed arc characteristics and simulates a single fault state; the dynamic arc model adjusts the arc characteristics in real time according to operating conditions (such as voltage and current). The definition of arc parameters includes defining the voltage-current characteristic curve of the arc, such as a linear model, an exponential model, or a piecewise model; simulating the influence of the physical length of the arc on its voltage and current characteristics, supporting fixed length and dynamic length changes; defining the dynamic response speed of the arc, which is used to simulate the time process of arc formation and extinction.

[0061] The interrupt module is used to simulate intermittent faults and controls the state change of the grounding switch by generating an interrupt signal. The selection of interrupt types includes timer interrupt, random interrupt, and conditional trigger interrupt, etc. The methods for generating interrupt signals include white noise, pulse generators, and time-dependent pulses, etc. The output interrupt signal is used to control the on-off of the grounding switch, supporting the simulation of continuous interrupt sequences, which is used to test the response ability of the distribution network in multiple intermittent faults.

[0062] In one embodiment, the selection of the ignition voltage change mode in the arc parameter module includes at least one of a linear mode, a pulse generator mode, a step mode, and a step with ramp mode. The linear mode allows setting a constant value or a vector of two elements. In the case of a vector of two elements, the arc ignition voltage will vary linearly within the fault time specified on the configuration module. The pulse generator mode requires a switching between two voltages and a pulse width (in seconds). The pulse width can be set as a constant value if the duration of the arc ignition voltage intervals is the same, or as a vector of two elements. The step mode allows setting the change of the arc ignition voltage in any pattern and the duration of each interval, which repeats throughout the fault time specified on the configuration module. The step with ramp mode has the same settings as the step mode. Additionally, there is an arc ignition voltage at the end of each defined voltage interval. Thus, the arc ignition voltage can change linearly and abruptly within the fault time.

[0063] In one embodiment, in the arc parameter module, an arc control signal is selected to be generated based on the Petersen theory or the Peters Slepian theory.

[0064] Figure 2 is a schematic structural diagram of a control subsystem provided by an embodiment of the present application, as Figure 2 shown, the control subsystem includes:

[0065] An initial phase control module, configured to generate an initial phase delay signal according to the initial voltage phase of the fault;

[0066] An arc fault module, configured to generate an arc control signal according to the fault current, the terminal voltage, and the arc fault and its type;

[0067] A logical AND module, configured to generate the arc fault trigger signal according to the fault signal, the initial phase delay signal, the arc control signal, and the interrupt signal.

[0068] Specifically, the control subsystem is the core logic processing unit of the single-phase grounding fault block, and is used to integrate multiple signals to generate an arc fault trigger signal. It combines the initial phase, the fault type, the logical relationship, and the interrupt signal to ensure an accurate simulation of the intermittent arc fault.

[0069] The Initial Phase Control Module InitialPha generates a corresponding initial phase delay signal based on the initial fault voltage phase, which is used to adjust the fault trigger time to be consistent with the operating state of the distribution network system. First, it receives the user-defined initial voltage phase value; then it synchronizes the voltage phase with the distribution network system cycle and calculates the corresponding delay time; finally, it outputs a delay signal to introduce a phase shift before the fault trigger to ensure that the time point of arc trigger conforms to the initial phase setting. The delay methods include fixed delay calculated directly according to the input phase value and dynamic delay that adjusts the phase delay in real time according to the system operating state. When the zero crossing of the voltage is detected, the timer starts, and after a user-defined time delay, the output SR flip-flop is set to 1, and the first trip of the grounding switch is enabled.

[0070] The Arcing Fault Module Arcing generates an arc control signal based on the arc fault and its type, accurately reflecting the dynamic behavior of different arc characteristics. The fault types include static arc with fixed arc characteristics, reflecting a single stable fault state, and dynamic arc with arc characteristics changing with system parameters (such as current and voltage), simulating complex fault dynamics. Based on the fault current, terminal voltage, and arc volt-ampere characteristic curve, it calculates the working state of the arc in real time and generates signals for controlling the arc trigger and extinction in combination with the simulation requirements.

[0071] The Logic AND Module Ctrl generates an arc fault trigger signal based on multiple input signals, including the fault signal, initial phase delay signal, arc control signal, and interrupt signal, to implement the logic of arc ignition and extinction. The fault signal is generated from the start time and end time of the fault, indicating whether a fault has occurred in the distribution network system; the initial phase delay signal is generated by the initial phase control module and is used to adjust the fault trigger time. In the configuration module, the moment of the phase voltage of the fault relative to the first zero crossing can be set, with the unit being radians, degrees, or seconds; the arc control signal is generated by the arc fault module, indicating the current state of the arc; the interrupt signal is generated by the interrupt module and is used to simulate intermittent faults. The Logic AND Module performs a logical AND operation on the input signals. When all input signals meet the conditions simultaneously, it outputs a high-level signal to trigger the arc fault, ensuring that the fault can only be triggered when multiple conditions are met simultaneously, avoiding false triggering or unreasonable fault behaviors. The output arc fault trigger signal is used to drive the state change of the grounding switch to achieve arc ignition or extinction.

[0072] In one embodiment, priorities are set within the Logic AND Module. If the interrupt signal is set to have priority, when the interrupt signal is at a low level, no matter what the other signals are, the arc will not be triggered; if the fault signal is set to have priority, when there is no fault signal input, the other signals are invalid. Generally, the interrupt takes precedence over arc extinction.

[0073] In one embodiment, the structure of the arc fault module is asFigure 7 As shown, the ignition and extinction of the arc are determined by the input of the SR flip-flop Bistable of the arc fault module. When the arc ignition condition is satisfied by measuring the voltage, the S input is set to 1.

[0074] Figure 3 is a partial structural schematic diagram of the arc fault module provided by an embodiment of the present application, as Figure 3 shown, the arc fault module includes:

[0075] A waiting time sub-module, which is used to record the arc ignition time and set the time constant for high-frequency component attenuation;

[0076] A signal filtering sub-module, which is used to extract the fundamental frequency component of the fault current.

[0077] Specifically, the waiting time sub-module and the signal filtering sub-module achieve high-fidelity simulation of complex arc fault behaviors by accurately modeling the arc ignition time and the attenuation process of its high-frequency components, combined with the extraction of the fundamental frequency component of the fault current. These modules improve the accuracy and physical authenticity of the model through the collaborative processing of time and frequency domains.

[0078] The waiting time sub-module records the arc ignition time to ensure that the time characteristics of the fault behavior can be accurately traced. The attenuation time constant of the high-frequency component is set to simulate the energy attenuation characteristics of the high-frequency components in the actual arc process. Each time the arc is ignited, the ignition timestamp t is recorded. The attenuation model combines the sampled values of the fault current to dynamically calculate the change of the high-frequency component and adjust the fault characteristics in real time. The attenuation model of the high-frequency component can be expressed as an exponential function:

[0079] A(t) = A 0 e -t / τ (1)

[0080] In the formula, A 0 is the initial amplitude, and τ is the attenuation time constant.

[0081] The signal filtering sub-module Filtering extracts the fundamental frequency component in the fault current, excludes the interference of high-frequency noise and harmonic components, and provides a pure fundamental frequency signal for subsequent arc behavior modeling and simulation. Filtering is achieved through a band-pass filter, a finite impulse response (FIR) or an infinite impulse response (IIR) filter.

[0082] The waiting time sub-module Waiting records the timestamp and triggers the high-frequency component attenuation process each time the arc is ignited, and outputs the ignition time and the dynamic high-frequency attenuation signal. The signal filtering sub-module extracts the fundamental frequency component from the fault current, while removing high-frequency noise and sub-harmonics, and outputs a pure fundamental frequency signal for simulating arc behavior. The high-frequency component attenuation signal is combined with the fundamental frequency component signal for comprehensive behavior modeling of the arc fault module.

[0083] In one embodiment, the structure of the waiting time sub-module is as Figure 8 shown. When the upper input of the switch SW_2 of the arc fault module is activated, the waiting time sub-module inputs and remembers the arc ignition time from the "Arc" block, and outputs a permission signal that allows the arc to extinguish only after the user-defined waiting time constant WaitTime, which can ensure the correct operation of arc extinction in an isolated or resistance grounded neutral network without high-frequency components and the delay introduced by the filter. Setting the waiting time can ensure that the arc extinguishes when the high-frequency components decay and the fundamental frequency component passes through zero. The waiting time constant WaitTime does not exceed 3 / 4 of the period and is not shorter than 3 / 8 of the period because most of the high-frequency components decay rapidly in an isolated or resistance grounded neutral point.

[0084] In one embodiment, the structure of the signal filtering sub-module is as Figure 9 shown. When the upper input of the switch SW_2 of the arc fault module is activated, signal filtering can be enabled to extract the fundamental frequency in the fault current. The user can define the natural frequency and return time constant of the low-pass filter in the parameters. The signal filtering sub-module records the zero-crossing of the fault current of the low-pass filter for the filter return time. Therefore, during the filter return time constant, the original signal is expected to cross zero and then the arc extinguishes.

[0085] Figure 4 is a schematic structural diagram of the zero-crossing sub-module provided by an embodiment of the present application, as Figure 4 shown, and the arc fault module further includes:

[0086] A zero-crossing sub-module for controlling arc extinction based on the zero-crossing detection signal of the fault current.

[0087] Specifically, the zero-crossing sub-module precisely controls the dynamic behavior of the grid ground fault. Its core is to detect the zero-crossing point of the fault current and control the arc extinction process, thereby simulating the natural extinction mechanism of arc faults in actual distribution networks under specific conditions. The application of zero-crossing detection can improve the authenticity of arc simulation and support the further optimization and testing of grid protection algorithms.

[0088] Under specific grounding conditions (such as grounding through an arc suppression coil), the arc usually extinguishes when the fault current passes through zero. The zero-crossing sub-module monitors the waveform of the fault current by sampling it in real time and uses digital signal processing technology to accurately identify its zero-crossing point. Here, the zero-crossing point is the switching point where the current value changes from positive to negative or from negative to positive. When the absolute value of the current is less than a preset zero-crossing threshold (∣I∣<∈), it is recognized as the zero-crossing point to avoid misjudgment caused by signal noise. An arc control signal is generated based on the zero-crossing detection result to control the ignition or extinction of the arc, reflecting the coupling relationship between the arc behavior and the power grid dynamics.

[0089] The zero-crossing sub-module ensures the accuracy of zero-crossing detection through advanced signal processing algorithms, avoiding false triggering caused by noise and high-frequency interference, and collaborating with other modules to form a more complex arc fault simulation logic.

[0090] In one embodiment, when the lower input of the switch SW_2 of the arc fault module is activated, the instantaneous fault current is input to the input terminal. Through the zero-crossing detector, a single pulse of a sample time is generated at the output and then input to the R input of the SR flip-flop. The zero-crossing sub-module needs to detect the exact zero-crossing instead of bouncing around the zero value at each sample time without a fault.

[0091] In one embodiment, as Figure 2 shown, the control subsystem further includes:

[0092] A fault limitation module for setting the limit on the number of arc faults and the time delay between two consecutive faults, and stopping fault triggering when the set number is exceeded.

[0093] Specifically, the fault limitation module is responsible for limiting the number of arc fault triggers and stopping the triggering behavior after the number of fault triggers exceeds the set threshold. At the same time, by setting the time delay between consecutive faults, it simulates the dynamic behavior of arc faults in the power grid to ensure that the fault model conforms to the actual power grid characteristics. Set the maximum number of arc fault triggers to avoid overly frequent fault triggering, which may affect the simulation performance or test results. When the number of triggers reaches the set threshold, further fault triggering is automatically stopped. Set the minimum time interval between two consecutive faults to prevent overly dense fault occurrences and simulate the intermittent behavior existing in actual arc faults.

[0094] Users can adjust the number of triggers and the time delay according to actual application requirements to adapt to different simulation scenarios. Prevent overly frequent fault triggering from impacting the power grid simulation environment or test equipment.

[0095] In one embodiment, as Figure 2 shown, the fault limitation module includes:

[0096] A counting limiter sub-module for calculating the number of occurred faults and disabling the arc fault trigger signal when the set number is reached;

[0097] A time delay sub-module for delaying the arc fault trigger signal according to a preset time delay value.

[0098] Specifically, the fault limiting module precisely controls the triggering behavior of the arc fault through the collaborative work of the counting limiter sub-module and the time delay sub-module. It not only limits the frequency of fault triggering but also ensures the physical authenticity and time consistency of the simulation process, and is applicable to various power grid simulation scenarios.

[0099] The counting limiter sub-module is responsible for real-time counting of the number of arc fault triggers. When the number of triggers reaches the preset upper limit, it disables the arc fault trigger signal to prevent excessive triggering. Initialize the fault counter C fault = 0. Each time a fault is triggered, the counter value is incremented C fault = C fault + 1. Preset the upper limit of the number of triggers N max , and the user can configure N according to the simulation requirements max , when the counter value reaches or exceeds N max , an enable signal (Enable = 0) is output to stop further fault triggering. The counting limiter sub-module can prevent excessive arc fault triggers from interfering with the simulation environment, support users to adjust the triggering upper limit according to the scenario, and adapt to different test requirements.

[0100] The time delay sub-module controls the time interval of arc fault triggering to ensure that the preset delay requirements are met between consecutive faults, simulating the intermittent behavior of arc faults in the actual power grid. Record the current timestamp t at each fault trigger last , calculate the time difference between the current trigger request time t current and the previous trigger time t last :

[0101] Δt = t current - t last (2)

[0102] If Δt ≥ T min (preset minimum time delay), allow triggering; otherwise, delay triggering. If Δt < T min , the module will keep the trigger signal disabled until the delay time ends.

[0103] The time delay sub-module simulates the time characteristics of actual arc faults, supports multiple time delay configurations, and adapts to different power grid characteristics.

[0104] In an embodiment, the counting limiter sub-module initializes the counter C fault= 0, the time delay sub-module initializes the time stamp t last = 0. After receiving the trigger request, first, the counting limiter sub-module determines whether the current count value exceeds the upper limit N max . If not exceeding the limit, it is handed over to the time delay sub-module to determine whether the time interval Δt meets T min . If both conditions are met, the arc fault signal is triggered; if any condition is not met, triggering is prohibited and the corresponding status or alarm signal is output. After each trigger, the counting limiter updates the counter value C fault = C fault + 1, and the time delay sub-module updates the time stamp t last .

[0105] Through strict control of counting limit and time delay, the physical authenticity of the simulation behavior is ensured. It supports users to freely adjust the number of triggers and time delay to adapt to various scenarios. It provides an alarm function when the trigger limit is exceeded or the delay is not met, enhancing the safety of the simulation process.

[0106] Figure 5 is the structural schematic diagram of the interrupt module provided by an embodiment of the present application. As Figure 5 shown, the interrupt module includes;

[0107] White noise generation sub-module 501, which is used to generate the interrupt signal according to random white noise;

[0108] Pulse generator sub-module 502, which is used to generate the interrupt signal according to the set period and pulse width;

[0109] Time-dependent pulse sub-module 503, which is used to define a single-signal switching time sequence for interrupt control.

[0110] Specifically, the interrupt module is used to generate an interrupt signal to simulate the dynamic behavior of intermittent faults in the actual power grid. By combining the functions of the white noise generation sub-module, the pulse generator sub-module, and the time-dependent pulse sub-module, complex and variable interrupt signal control can be realized, providing diverse signal inputs for the simulation of arc faults.

[0111] The white noise generation sub-module generates an interrupt signal based on random white noise to simulate the intermittent fault behavior with strong randomness in a complex power grid. A random number generation algorithm is used to generate a white noise signal with zero mean and constant power spectral density. The generated white noise signal is processed by a threshold comparator: when the noise signal intensity A noise exceeds the set threshold A threshold , a high-level signal is output; otherwise, a low-level signal is output. The white noise generation sub-module can simulate the arc fault behavior with strong randomness to test the response performance of the distribution network under random signal interference.

[0112] The pulse generator sub-module generates an interrupt signal with a regular period by setting the period and pulse width, simulating a periodic intermittent fault. According to the period T and pulse width W set by the user, a periodic pulse signal is generated: the high-level duration is W, and the low-level duration is T-W, forming a square wave signal with a duty cycle of Duty . The user can adjust W and T to achieve different duty cycles and control the duration and frequency of the interrupt signal. The pulse generator sub-module can simulate regular fault behaviors to test the stability and response speed of the distribution network under periodic interrupt signals.

[0113] The time-dependent pulse sub-module defines the switching time sequence of a single signal, which is used to generate an irregular interrupt signal to implement complex interrupt control logic. Select or generate a set of time sequences {t 1 , t 2 , …, t n}, representing the switching time points of the interrupt signal. According to the time sequence, the signal is controlled to switch between the high level (on) and the low level (off). The time-dependent pulse sub-module can simulate non-periodic and complex intermittent faults to test the response performance of the distribution network under complex interrupt signal control.

[0114] Each time an interrupt signal is generated, one of the white noise generation sub-module, the pulse generator sub-module, and the time-dependent pulse sub-module is selected to support the generation of random, periodic, and irregular signals, meeting the requirements of different simulation scenarios. The parameters of each sub-module can be flexibly adjusted to adapt to different fault types and experimental requirements.

[0115] In one embodiment, as Figure 10 shown, a test scheme for a 10kV distribution network with two feeders is designed. The scheme includes an ideal three-phase 10kV voltage source located above the system impedance, and a single-phase ground fault block connected to the bus. For the solver of the test scheme, the simulation step size is fixed, and the sampling time value has a significant impact on the high-frequency components in the fault current. The arc fault simulations are performed respectively according to the Petersen arc theory and the Peters-Slepian arc theory to analyze the current and voltage waveforms.

[0116] The present application provides a simulation model for intermittent arc faults in a distribution network. The model includes: a single-phase grounding fault block; the single-phase grounding fault block includes a grounding switch and a control subsystem; the grounding switch is connected to the control subsystem and is used to change its state according to the arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch; the control subsystem is used to determine the operation of the grounding switch and generate an arc fault trigger signal according to the received fault current and terminal voltage, so as to implement the arc ignition and extinction logic. The simulation model for intermittent arc faults in the distribution network provided by the present application realizes the accurate simulation of the dynamic characteristics of intermittent arc faults and ensures the reliability of the simulation results. Among them, the control subsystem supports multiple trigger logics and parameter configurations and can be flexibly adjusted according to different research requirements; by simplifying the modeling of the grounding switch, the computational complexity is significantly reduced and the simulation efficiency is improved.

[0117] In addition, the present application also provides a simulation device for intermittent arc faults in a distribution network, including the simulation model for intermittent arc faults in a distribution network as described in any of the above embodiments, which is used to simulate intermittent arc faults in the distribution network, so as to perform fault characteristic analysis and fault detection.

[0118] The present application provides a simulation model and device for intermittent arc faults in a distribution network. The model includes: a single-phase grounding fault block; the single-phase grounding fault block includes a grounding switch and a control subsystem; the grounding switch is connected to the control subsystem and is used to change its state according to the arc fault trigger signal generated by the control subsystem; the grounding switch is constructed based on an ideal switch; the control subsystem is used to determine the operation of the grounding switch and generate an arc fault trigger signal according to the received fault current and terminal voltage, so as to implement the arc ignition and extinction logic. The simulation model and device for intermittent arc faults in the distribution network provided by the present application realizes the accurate simulation of the dynamic characteristics of intermittent arc faults and ensures the reliability of the simulation results. Among them, the control subsystem supports multiple trigger logics and parameter configurations and can be flexibly adjusted according to different research requirements; by simplifying the modeling of the grounding switch, the computational complexity is significantly reduced and the simulation efficiency is improved.

[0119] In the description of this specification, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to this application. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0120] The descriptions with reference to terms such as "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. The order of steps involved in each embodiment is used to schematically illustrate the implementation of this application, and the order of steps is not limited and can be adjusted appropriately as needed.

[0121] In the description of this application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0122] The above-described specific embodiments have further elaborated on the purpose, technical solutions, and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not used to limit the protection scope of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A simulation model for intermittent arc faults in a distribution network, characterized in that: include: Single-phase to ground fault block; The single-phase grounding fault block includes a grounding switch and a control subsystem; The grounding switch is connected to the control subsystem and is used to change the state according to the arc fault trigger signal generated by the control subsystem; The grounding switch is constructed based on an ideal switch; The control subsystem is used to determine the operation of the grounding switch according to the received fault current and terminal voltage and generate an arc fault trigger signal to implement arc ignition and extinguishing logic.

2. The intermittent arc fault simulation model of the distribution network according to claim 1, characterized in that: The single-phase ground fault block also includes: A configuration module, used to set the parameters of the grounding switch, the grounding resistance, the start time and end time of the fault, and the initial voltage phase of the fault; Arc parameter module, used to define arc faults and their types; An interrupt module is used to generate interrupt signals according to the interrupt type to simulate intermittent faults.

3. The intermittent arc fault simulation model of the distribution network according to claim 1, characterized in that: The control subsystem comprises: An initial phase control module, used for generating an initial phase delay signal according to an initial voltage phase of a fault; An arc fault module, configured to generate an arc control signal according to the fault current, the terminal voltage and the arc fault and its type; A logic and module is used to generate the arc fault trigger signal according to the fault signal, the initial phase delay signal, the arc control signal and the interrupt signal.

4. The intermittent arc fault simulation model of the distribution network according to claim 3, characterized in that: The arc fault module comprises: Waiting time submodule, used to record the arc ignition time and set the time constant of high-frequency component attenuation; The signal filtering submodule is used to extract the fundamental frequency component of the fault current.

5. The intermittent arc fault simulation model of the distribution network according to claim 3, characterized in that: The arc fault module also includes: The zero-crossing submodule is used to control arc extinction based on the zero-crossing detection signal of the fault current.

6. The intermittent arc fault simulation model of the distribution network according to claim 1, characterized in that: The control subsystem also includes: The fault limit module is used to set the arc fault number limit and the time delay between two consecutive faults, and stop the fault triggering when the set number is exceeded.

7. The intermittent arc fault simulation model of the distribution network according to claim 6, characterized in that: The fault limiting module comprises: a counter limiter submodule, for counting the number of faults that have occurred and disabling the arc fault trigger signal when a set number of faults has been reached; The time delay submodule is used to delay the arc fault trigger signal according to a preset time delay value.

8. The intermittent arc fault simulation model of the distribution network according to claim 2, characterized in that: The ignition voltage variation mode of the arc parameter module supports at least one of a linear mode, a pulse generator mode, a step mode, and a step-with-ramp mode.

9. The intermittent arc fault simulation model of the distribution network according to claim 2, characterized in that: The interrupt module includes: A white noise generation submodule, used for generating the interrupt signal according to random white noise; A pulse generator submodule, used for generating the interrupt signal according to a set period and pulse width; The time-dependent pulse submodule is used to define the single signal switching time sequence for interrupt control.

10. A distribution network intermittent arc fault simulation device, characterized in that: It comprises a distribution network intermittent arc fault simulation model as described in any one of claims 1 to 9, which is used to simulate intermittent arc faults in the distribution network, so as to perform fault characteristic analysis and fault detection.

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