Method and system for simulating latent fault of medium-voltage distribution cable

Abstract

The invention discloses a method and system for simulating a latent fault of a medium-voltage distribution cable. The method comprises the following steps: establishing a target cable latent fault model based on an arc model; according to the target cable latent fault model, establishing a first simulation model, and obtaining a first fault simulation waveform; according to the first fault simulation waveform, obtaining a relationship between the target parameter and a fault feature in a target cable latent fault model; and obtaining an optimal target parameter to determine a final target cable latent fault model. By simulating a cable latent fault, the potential problem of the cable can be predicted and identified more accurately, so that a maintenance measure is taken in advance, and occurrence of a sudden fault is avoided. By optimizing the target parameters, it can be ensured that the simulation result is highly consistent with the waveform feature of the actual cable latent fault, and therefore the effectiveness of fault prevention and protection measures is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable fault modeling, and in particular to a method and system for simulating latent faults of medium-voltage distribution cables. Background Art

[0002] As a key equipment for power transmission and distribution, power cables are widely used in the construction of power transmission and distribution networks in cities due to their beautiful appearance, small footprint, and high power supply safety. At the same time, power supply to coastal islands, grid connection between islands or the mainland, offshore oil and gas extraction, offshore work platform construction, and power transmission in wind farms also require the use of cables for power transmission. At present, affected by various factors such as cable design and production, actual operation and maintenance, and operating environment, cable failures often occur, and cables have become one of the safety hazards in the actual operation of the power grid.

[0003] The operating experience of medium-voltage cables shows that before a permanent fault occurs, an instantaneous, self-recovering arc grounding fault may occur at the same location. These faults are short-lived and have low fault energy. Therefore, when a fault occurs, traditional protection devices cannot be activated. Moreover, such faults can disappear in a short time (1 / 4-4 cycles) and generally do not affect the normal power transmission and distribution of the cable. Most of these faults will eventually develop into permanent grounding faults, which have the characteristics of latent faults. Therefore, this self-recovering, low-energy arc fault that occurs at the same location of the cable is called a cable latent fault. When a latent fault occurs in the cable, conventional protection and fault indicators will not be activated. Moreover, the latent fault current waveform is highly consistent with the initial waveforms of other overcurrents (such as motor startup, load transients, permanent grounding faults, etc.), which makes it difficult to prevent, identify and protect against latent faults.

[0004] The study of latent cable faults is conducive to the development of cable line condition maintenance, and is of great significance for preventing permanent cable faults, reducing power outage losses caused by faults, and ensuring the safe operation of power systems. The simulation of latent cable faults is the basis for the identification and detection of latent faults in medium-voltage cables. Constructing a model that can accurately restore latent cable faults is a prerequisite for the smooth development of research such as fault location and preventive protection. Therefore, how to select a suitable model to simulate latent faults in medium-voltage cables is a key issue. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for simulating latent faults of medium-voltage distribution cables, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for simulating a latent fault of a medium voltage distribution cable, comprising:

[0010] Establish a target cable latent fault model based on arc model;

[0011] According to the target cable latent fault model, a first simulation model is established, and a first fault simulation waveform is obtained;

[0012] Acquire the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform;

[0013] Obtain the optimal target parameters to determine the final target cable latent fault model.

[0014] As a preferred solution of the method for simulating latent faults of medium-voltage distribution cables described in the present invention, the fault characteristics in the target cable latent fault model include waveform characteristics of several first fault simulation waveforms.

[0015] As a preferred solution of the method for simulating latent faults of medium-voltage distribution cables according to the present invention, the relationship between the target parameter obtained according to the first fault simulation waveform and the fault characteristics in the target cable latent fault model includes:

[0016] Preset target parameters, wherein the target parameters at least include arc characteristic voltage, arc characteristic resistance and time constant;

[0017] Through the first analysis strategy, a relationship between a target parameter and waveform characteristics of a plurality of first fault simulation waveforms is established.

[0018] As a preferred solution of the method for simulating latent faults of medium voltage distribution cables according to the present invention, the first analysis strategy includes:

[0019] Using the control variable method, several groups of parameter conditions are set for all target parameters;

[0020] The first fault simulation waveform under different parameter combinations is obtained according to the plurality of groups of parameter conditions.

[0021] As a preferred solution of the method for simulating latent faults of medium voltage distribution cables according to the present invention, the step of establishing a target cable latent fault model based on an arc model comprises:

[0022] The part of the water tree and electric tree channel where arc discharge does not occur is equivalent to a constant resistance;

[0023] Connecting the constant resistor in series with the arc model;

[0024] The whole series is defined as the target cable latent fault model.

[0025] As a preferred solution of the method for simulating latent faults of medium-voltage distribution cables described in the present invention, the method of using control variables to set several groups of parameter conditions for all target parameters includes:

[0026] Select any first target parameter as a variable parameter, and the other target parameters as constant parameters;

[0027] Grouping the first target parameters to set a plurality of groups of first target parameters;

[0028] Each group of first target parameters forms several groups of parameter conditions with the remaining target parameters;

[0029] The first fault simulation waveform under different parameter combinations is obtained according to the plurality of groups of parameter conditions.

[0030] As a preferred solution of the method for simulating latent faults of medium-voltage distribution cables described in the present invention, the arc model is a mathematical model of time constant, arc static equivalent conductance and arc instantaneous conductance.

[0031] In a second aspect, the present invention provides a system for simulating latent faults of medium voltage distribution cables, comprising:

[0032] A model building module, used to build a target cable latent fault model based on an arc model;

[0033] A simulation module, used to establish a first simulation model according to the target cable latent fault model, and obtain a first fault simulation waveform;

[0034] An analysis module, used for obtaining the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform;

[0035] The model determination module is used to obtain the optimal target parameters to determine the final target cable latent fault model.

[0036] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0037] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes a method and system for simulating latent faults of medium-voltage distribution cables, establishes a target cable latent fault model based on an arc model; according to the target cable latent fault model, establishes a first simulation model, and obtains a first fault simulation waveform; according to the first fault simulation waveform, obtains the relationship between the target parameter and the fault characteristics in the target cable latent fault model; obtains the optimal target parameter to determine the final target cable latent fault model. By simulating latent cable faults, potential problems of the cable can be more accurately predicted and identified, so that maintenance measures can be taken in advance to avoid the occurrence of sudden faults. By optimizing the target parameters, the present invention can ensure that the simulation results are highly consistent with the waveform characteristics of the actual cable latent faults, thereby improving the effectiveness of fault prevention and protection measures. The simulation method and system of the present application are not only applicable to medium-voltage distribution cables, but can also be extended to cable systems of other voltage levels, and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0040] Figure 1 A method flow chart of a method and system for simulating latent faults of medium-voltage distribution cables provided by one embodiment of the present invention;

[0041] Figure 2 A schematic diagram of a latent fault waveform of a medium-voltage distribution cable of a method and system for simulating a latent fault of a medium-voltage distribution cable provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of a cable latent fault equivalent model of a method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention;

[0043] Figure 4A method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention is a medium-voltage cable distribution system with a classic low-resistance system established by using a Bergeron cable model in PSCAD electromagnetic simulation software;

[0044] Figure 5 A schematic diagram of the structure of a medium-voltage distribution cable of a method and system for simulating latent faults of a medium-voltage distribution cable provided by an embodiment of the present invention;

[0045] Figure 6 A method and system for simulating latent faults of medium-voltage distribution cables provided in one embodiment of the present invention includes a cable latent fault simulation model built using PSACD / EMTD;

[0046] Figure 7 A schematic diagram of a simulation waveform of a latent fault of a medium-voltage distribution cable obtained by running a simulation model of a method and system for simulating a latent fault of a medium-voltage distribution cable provided by an embodiment of the present invention;

[0047] Figure 8 A method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention maintains arc characteristic resistance of 0.005Ω and arc time constant of 0.20ms, and changes characteristic voltage between 0.30-4kV to obtain simulated fault waveform schematic diagrams of ten groups of fault parameters, a). half-cycle latent fault, b). one-cycle latent fault, c). multi-cycle latent fault;

[0048] Fig. 9 A method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention maintains an arc characteristic voltage of 2kV and an arc time characteristic constant of 0.20ms, and changes the arc characteristic resistance between 0.005Ω-0.015Ω to obtain simulated fault waveform schematic diagrams of ten groups of fault parameters, a). half-cycle latent fault, b). one-cycle latent fault, c). multi-cycle latent fault;

[0049] Fig.10 A method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention maintains the arc characteristic voltage at 2kV and the arc characteristic resistance at 0.005Ω, and changes the arc time characteristic constant τ between 0.20ms-0.40ms to obtain simulated fault waveform schematic diagrams of ten groups of fault parameters, a). half-cycle latent fault, b). one-cycle latent fault, c). multi-cycle latent fault;

[0050] Fig.11An internal structural diagram of a computer device of a method and system for simulating latent faults of medium-voltage distribution cables provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0052] Example 1

[0053] Reference Figure 1-Figure 11 , which is the first embodiment of the present invention, provides a method and system for simulating latent faults of medium-voltage distribution cables, including:

[0054] There are some limitations in the existing technology, such as the inability to accurately simulate the potential faults that cables may encounter in actual operation, and the inability to effectively predict and identify these potential problems. These problems may cause the cable to suddenly fail during operation, affecting the stability and reliability of the power system.

[0055] The present application provides a method that can effectively solve the above-mentioned problems. Next, a method for simulating latent faults of medium-voltage distribution cables will be described in detail in combination with multiple embodiments.

[0056] Figure 1 A method flow chart of a method and system for simulating latent faults of medium voltage distribution cables is shown, comprising:

[0057] S101, establishing a target cable latent fault model based on an arc model;

[0058] In an optional embodiment, there are many types of arc models that can establish the target cable latent fault model, such as the Kizilcay arc model, the Koch model, the Lee model, etc. These models have their own characteristics and can simulate arc behaviors under different conditions. For example, the Kizilcay arc model can simulate the dynamic characteristics of the arc, while the Lee model focuses on the thermodynamic characteristics of the arc. Selecting a suitable arc model is crucial for accurately simulating cable latent faults.

[0059] In an optional embodiment, the Koch model is relatively complex, requires a large amount of calculation, and requires high-performance computing resources. Ensure that the computing platform can support such high computing requirements. The model requires many parameters, and some parameters are difficult to measure directly through experiments, requiring complex calculations and fitting. Ensure that these parameters can be obtained or estimated. The initial condition setting of the model is relatively complex and requires precise parameter input, otherwise it may affect the accuracy of the simulation results.

[0060] In an optional embodiment: The Lee model is based on some simplifying assumptions and may not be accurate enough in some cases. Make sure these assumptions are reasonable in the application scenario. The model is very sensitive to the choice of parameters and needs careful calibration. Make sure these parameters can be obtained or estimated. The Lee model is mainly used for arcs in gases and may not be accurate enough for arcs in solid media.

[0061] In the embodiment of the present application, since the dynamic characteristics of the reaction arc are very accurate and comprehensive accurate calculations are performed, the computing resource cost is not considered. The Kizilcay model is based on a detailed physical mechanism and can better reflect the dynamic characteristics of the arc, which helps to deeply understand the physical process of the arc. The parameters required for the model can be obtained by experimental measurement, which is convenient for practical application and reduces the complexity of parameter estimation. The Kizilcay model performs well in the simulation of latent faults of medium-voltage distribution cables and can better describe the dynamic behavior of the arc. Compared with the Koch model, the Kizilcay model has a lower computational complexity and can be run on most computing platforms, which is suitable for practical engineering applications. Therefore, it is selected to establish a target cable latent fault model based on the Kizilcay arc model.

[0062] In the embodiment of the present application, the arc model is a mathematical model about the time constant, the arc static equivalent conductance and the arc instantaneous conductance.

[0063] In the embodiment of the present application, the mathematical expression of the Kizilcay arc model is as follows:

[0064]

[0065] Among them, τ is the time constant; G is the static equivalent conductance of the arc; g is the instantaneous conductance of the arc, and it satisfies the following quantitative relationship with the instantaneous resistance of the arc:

[0066]

[0067] The static equivalent conductance of the arc is the arc current i f and static arc voltage u st The relevant function of (t):

[0068]

[0069] u st (t) = u 0 +r 0 |i f (t)|

[0070] Among them, u 0 is the characteristic voltage of the arc; r 0 is the characteristic resistance of the arc.

[0071] Combining the above formulas, we can get the complete formula of Kizilcay dynamic arc model:

[0072]

[0073] In an embodiment of the present application, establishing a target cable latent fault model based on an arc model includes:

[0074] The part of the water tree and electric tree channel where arc discharge does not occur is equivalent to a constant resistance;

[0075] Connect a constant resistor in series with the arc model;

[0076] The whole series is defined as the target cable latent fault model.

[0077] In an optional embodiment, since most of the latent faults of cables are caused by insulation such as water trees and electrical trees, the arc model alone cannot accurately simulate the latent faults. Therefore, the part of the water tree and electrical tree channel where arc discharge does not occur is equivalent to a constant resistor, which is connected in series with the arc model to better describe the latent fault. The target cable latent fault equivalent model is as follows: Figure 3 shown.

[0078] In the embodiment of the present application, the equivalent model of the latent fault of the medium voltage cable is regarded as the arc resistance R arc and defect channel equivalent resistance R 0 The model of latent fault of target cable can be expressed as:

[0079] u f (t) = i f (t)(R 0 +R arc (t))

[0080] Among them, u f is the voltage with latent fault, i f The current of latent fault.

[0081] It should be noted that the establishment of the latent fault model of the target cable not only considers the arc model, but also combines the characteristics of the cable insulation material. By simulating the formation process of water tree and electric tree channels, the latent faults that may occur in the actual operation of the cable can be predicted more accurately. The formation of water tree and electric tree channels is closely related to the chemical structure and physical state of the cable insulation material, as well as the voltage and temperature in the cable operation environment. Therefore, when establishing the latent fault model of the target cable, it is necessary to conduct an in-depth analysis of the characteristics of the cable insulation material. The chemical structure and physical state of the insulation material determine its response to the electric field, thereby affecting the formation of water tree and electric tree channels. For example, polyethylene (PE) and cross-linked polyethylene (XLPE) are commonly used insulation materials in medium voltage cables. They will be affected by the electric field, temperature and mechanical stress during long-term operation, resulting in material aging and defects.

[0082] It should be noted that the establishment of the target cable latent fault model can provide a scientific basis for cable maintenance and fault prevention. Through simulation analysis, potential fault points can be discovered in advance, so that corresponding maintenance measures can be taken to reduce the occurrence of sudden faults.

[0083] S102, establishing a first simulation model according to a target cable latent fault model, and obtaining a first fault simulation waveform;

[0084] In an optional embodiment, according to the target cable latent fault model, the first simulation model can be established by using the Bergeron cable model in the PSCAD electromagnetic simulation software to establish a low-resistance system medium-voltage cable distribution system, connecting n cable feeders at the end, and performing fault simulation in the distribution system model built on the PSCAD / EMTDC platform to observe the latent fault equivalent waveform (i.e., the first fault simulation waveform);

[0085] In an optional embodiment, according to the target cable latent fault model, the first simulation model can also be established by using the Simscape Electrical toolbox in MATLAB / Simulink to establish a cable model and an arc model. Simulation parameters such as simulation time, step size, etc. are configured to ensure the accuracy and stability of the simulation results. A latent fault is injected into the cable model to observe the fault waveform (i.e., the first fault simulation waveform).

[0086] In an optional embodiment, according to the target cable latent fault model, the first simulation model can also be established in COMSOL Multiphysics to establish a cable model and an arc model. Simulation parameters such as simulation time, step size, etc. are configured to ensure the accuracy and stability of the simulation results. A latent fault is injected into the cable model to observe the fault waveform (i.e., the first fault simulation waveform).

[0087] In an optional embodiment, OpenDSS (Open Distribution System Simulator), ATP-EMTP (Alternative Transients Program-Electromagnetic Transients Program) and other methods may also be selected for simulation, which is not limited here.

[0088] In the embodiment of the present application, a medium-voltage cable distribution system in a small resistance system is established using the Bergeron cable model in the PSCAD electromagnetic simulation software, and n cable feeders are connected to the ends. A fault simulation is performed in the distribution system model built on the PSCAD / EMTDC platform to observe the equivalent waveform of the latent fault (i.e., the first fault simulation waveform);

[0089] In the embodiment of the present application, a PSCAD / EMTDC simulation model is built according to the actual fault distribution network cable line parameters on site. The present application takes the power supply voltage of 110kV, which is reduced to 10kV by a step-down transformer and connected to n cable feeders as an example. The cable parameters are shown in Table 1, and the simulation model and cable structure schematic diagram are shown in Table 1. Figure 4 — Figure 6 As shown;

[0090] Table 1 Cable parameters

[0091]

[0092] In the embodiment of the present application, the selection of cable parameters is based on actual cable line data to ensure the reality and reliability of the simulation results. The cable parameters listed in Table 1 include conductor radius, insulation radius, armor radius, shell radius, conductor resistivity, relative permeability and relative dielectric constant, etc. These parameters are crucial for the electrical performance and fault simulation of the cable. By accurately setting these parameters, the behavior of the cable under different conditions, including normal operation and fault conditions, can be more accurately simulated.

[0093] It should be noted that in the distribution system model built on the PSCAD / EMTDC platform, by setting appropriate simulation time, step size and other parameters, the stability of the simulation process and the accuracy of the results can be ensured. The establishment of the simulation model and the conduction of fault simulation make it possible to observe the equivalent waveform of the latent fault, that is, the first fault simulation waveform. This waveform is crucial for analyzing and understanding the characteristics of the cable latent fault, because it can reveal the voltage and current changes when the fault occurs.

[0094] It should be noted that by injecting latent faults into the simulation model, the fault waveform can be further observed and analyzed, thus providing a scientific basis for cable maintenance and fault prevention. In this way, potential fault points can be discovered in advance and corresponding maintenance measures can be taken to reduce the occurrence of sudden faults and improve the reliability and safety of the cable system.

[0095] S103, acquiring a relationship between a target parameter and a fault feature in a target cable latent fault model according to the first fault simulation waveform;

[0096] In the embodiments of the present application, Figure 2 A schematic diagram of a latent fault waveform of a medium-voltage distribution cable of a method and system for simulating latent faults of a medium-voltage distribution cable is provided in an embodiment, wherein the upper part is a current fault waveform and the lower part is a voltage fault waveform. Both the current fault waveform and the voltage fault waveform show waveforms at 1 / 4 cycle, 1 / 2 cycle or multiple cycle latent faults.

[0097] In the embodiment of the present application, the relationship between the target parameter and the fault characteristics in the target cable latent fault model is obtained according to the first fault simulation waveform, including:

[0098] Preset target parameters, the target parameters at least include arc characteristic voltage, arc characteristic resistance and time constant;

[0099] Through the first analysis strategy, a relationship between a target parameter and waveform characteristics of a plurality of first fault simulation waveforms is established.

[0100] In the embodiment of the present application, the fault characteristics in the target cable latent fault model include waveform characteristics of several first fault simulation waveforms.

[0101] In an optional embodiment, the waveform characteristics of the first fault simulation waveform may include key characteristics such as crests, troughs, wave widths, rising edges and falling edges. By analyzing these characteristics, latent faults in the cable can be more accurately identified and located. For example, the appearance of crests and troughs may indicate the location of arc discharge, while changes in wave width may reflect the severity of the fault. Changes in the slopes of the rising and falling edges can be used to determine the dynamic characteristics of the fault. Through the comprehensive analysis of these waveform characteristics, more detailed and accurate information can be provided for cable maintenance and fault diagnosis.

[0102] In the embodiment of the present application, the waveform characteristics of the first fault simulation waveform are not restricted, and relevant technical personnel can select waveform characteristics according to actual needs. For example, in the present application, peaks, troughs, wave widths, rising and falling edges, and waveform trends are selected as waveform characteristics for analysis.

[0103] In an optional embodiment, the target parameters may include arc characteristic voltage, arc characteristic resistance, time constant, fault duration, fault occurrence frequency, etc.

[0104] In the embodiment of the present application, the target parameters are selected as arc characteristic voltage, arc characteristic resistance and time constant for analysis, and the arc characteristic voltage u is obtained by comparing and analyzing the fault phase current waveform obtained by simulating and analyzing different fault parameters. 0 , characteristic resistance r of the arc 0 And the influence of three parameters of time constant τ on fault characteristics:

[0105] In an optional embodiment, the first analysis strategy can be implemented by multiple regression analysis, time series analysis, neural network model, control variable method and other methods. These analysis strategies can help extract key information from complex simulation data and establish a mathematical model between target parameters and fault characteristics. Through such a model, it is possible to predict potential faults that may occur in cables under different conditions and evaluate the possibility of fault occurrence.

[0106] In the embodiment of the present application, the first analysis strategy includes:

[0107] Using the control variable method, several groups of parameter conditions are set for all target parameters;

[0108] The first fault simulation waveform under different parameter combinations is obtained according to several groups of parameter conditions.

[0109] In the embodiment of the present application, the control variable method is adopted to set several groups of parameter conditions for all target parameters respectively, including:

[0110] Select any first target parameter as a variable parameter, and the other target parameters as constant parameters;

[0111] Grouping the first target parameters and setting a plurality of groups of the first target parameters;

[0112] Each group of first target parameters forms several groups of parameter conditions with the remaining target parameters;

[0113] The first fault simulation waveform under different parameter combinations is obtained according to several groups of parameter conditions.

[0114] In the embodiments of the present application, Figure 7 The following is a schematic diagram of the cable latent fault simulation waveform, based on Figure 7 It can analyze the potential cable faults and conduct follow-up research such as feature extraction and fault identification;

[0115] In the embodiment of the present application, the single variable principle in the control variable method is adopted to set ten groups of parameter conditions for the three parameters respectively, and the fault waveforms under different parameter combinations are obtained, such as Figure 8 — Fig.10 As shown;

[0116] In the embodiment of the present application, the arc characteristic voltage u 0 Impact on latent fault characteristics, maintaining arc characteristic resistance r 0 The characteristic voltage u is changed to 0.005Ω and the arc time constant τ is 0.20ms. 0 Ten groups of fault parameters varying between 0.30-4kV are simulated under these ten groups of parameters to obtain fault waveforms under different parameters. Analysis of the fault waveform shows that: 0 As the voltage increases between 0.30 and 4 kV, the peak value of the arc current waveform decreases gradually. Therefore, it is considered that the characteristic voltage u 0 It is negatively correlated with the arc size.

[0117] In the embodiment of the present application, the arc characteristic resistance r 0 The influence of latent fault characteristics, keeping the arc characteristic voltage at 2kV and the arc time characteristic constant τ at 0.20ms unchanged, changing the arc characteristic resistance r 0 Ten groups of fault parameters varying between 0.005Ω and 0.015Ω. Under these ten groups of parameters, simulations were performed to obtain fault waveforms under different parameters. Analysis of the fault waveforms shows that: 0 The arc waveform remains basically unchanged, so it is considered that the characteristic resistance r 0 The impact on the arc model is not significant.

[0118] In the embodiment of the present application, the influence of the time constant τ on the latent fault characteristics keeps the arc characteristic voltage at 2kV and the arc characteristic resistance at 0.005Ω unchanged, and changes the arc time characteristic constant τ between 0.20ms-0.40ms to ten sets of fault parameters. Simulations were performed under these ten sets of parameter conditions to obtain fault waveforms under different parameter conditions. Analysis of the fault waveform shows that: as the time characteristic constant τ increases from 0.20ms to 0.40ms, the peak value of the arc current waveform will gradually decrease in the first half cycle of the arc fault, and the arc waveform will remain basically unchanged thereafter. Therefore, it is believed that the time characteristic constant τ is only negatively correlated with the development trend of the first half cycle of the arc.

[0119] In an optional embodiment, relevant technicians can set more groups of parameter conditions to further refine the relationship between the fault characteristics and the target parameters.

[0120] In the embodiment of the present application, by analyzing the waveforms under different parameter conditions, the influence of arc characteristic voltage, characteristic resistance and time constant on the latent fault characteristics of the cable can be obtained: as the arc characteristic voltage continues to increase between 0.30-4kV, the peak value of the arc current waveform will gradually decrease, so it is believed that the characteristic voltage and the arc size are negatively correlated; as the time characteristic constant increases between 0.20ms-0.40ms, in the first half of the cycle of the arc fault, the peak value of the arc current waveform will gradually decrease, and the arc waveform will remain basically unchanged thereafter, so it is believed that the time characteristic constant is only negatively correlated with the development trend of the first half of the arc cycle; and by changing the value of the arc characteristic resistance, the arc waveform remains basically unchanged, so it is believed that the characteristic resistance r0 has little effect on the arc model.

[0121] In an optional embodiment, relevant technical personnel may adopt the multi-variable design in the control variable method, but the idea overlaps with the present application, and therefore, both should be within the actual protection scope of the present application.

[0122] It should be noted that the relationship between the target parameter and the fault characteristics in the target cable latent fault model obtained according to the first fault simulation waveform can provide a more accurate basis for the prediction and diagnosis of cable faults. By simulating the waveform changes under different fault parameters, we can have a deeper understanding of the latent fault modes that may occur in the actual operation of the cable. In addition, through the control variable method, the influence of each parameter on the fault characteristics can be effectively isolated, thereby providing scientific decision-making support for cable maintenance and fault prevention. In practical applications, this method helps to improve the reliability and safety of the cable system, reduce power outages caused by faults, and thus reduce economic losses and improve social and economic benefits.

[0123] S104, obtaining optimal target parameters to determine a final target cable latent fault model.

[0124] In the embodiment of the present application, through the continuous combination of multiple fault characteristic results, the present application finally sets the arc characteristic voltage to 2kV, the time characteristic constant to 0.2ms, and the fault characteristic resistance to 0.005Ω. The latent fault equivalent model proposed in the present application can better simulate the latent fault of the medium voltage distribution cable.

[0125] In summary, the present invention proposes a method for simulating latent faults of medium-voltage distribution cables, establishing a target cable latent fault model based on an arc model; establishing a first simulation model according to the target cable latent fault model, and obtaining a first fault simulation waveform; obtaining the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform; obtaining the optimal target parameter to determine the final target cable latent fault model. By simulating latent faults of cables, potential problems of cables can be more accurately predicted and identified, so that maintenance measures can be taken in advance to avoid the occurrence of sudden faults. By optimizing the target parameters, the present invention can ensure that the simulation results are highly consistent with the waveform characteristics of the actual cable latent faults, thereby improving the effectiveness of fault prevention and protection measures. The simulation method and system of the present application are not only applicable to medium-voltage distribution cables, but can also be extended to cable systems of other voltage levels, and have broad application prospects.

[0126] This embodiment also provides a system for simulating latent faults of medium voltage distribution cables, including:

[0127] A model building module, used to build a target cable latent fault model based on an arc model;

[0128] A simulation module, used to establish a first simulation model according to a latent fault model of a target cable, and obtain a first fault simulation waveform;

[0129] An analysis module, used for obtaining the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform;

[0130] The model determination module is used to obtain the optimal target parameters to determine the final target cable latent fault model.

[0131] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0132] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Fig.11As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for simulating latent faults of medium-voltage distribution cables is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0133] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0134] Establish a target cable latent fault model based on arc model;

[0135] According to the latent fault model of the target cable, a first simulation model is established, and a first fault simulation waveform is obtained;

[0136] Acquire the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform;

[0137] Obtain the optimal target parameters to determine the final target cable latent fault model.

[0138] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0139] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0140] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0141] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0142] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0143] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0144] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for simulating latent faults of medium voltage distribution cables, characterized in that: include: Establish a target cable latent fault model based on arc model; According to the target cable latent fault model, a first simulation model is established, and a first fault simulation waveform is obtained; Acquire the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform; Obtain the optimal target parameters to determine the final target cable latent fault model.

2. The method for simulating latent fault of medium voltage distribution cable according to claim 1, characterized in that: The fault characteristics in the target cable latent fault model include waveform characteristics of a plurality of first fault simulation waveforms.

3. The method for simulating latent fault of medium voltage distribution cable according to claim 2, characterized in that: The relationship between the target parameter obtained according to the first fault simulation waveform and the fault characteristics in the target cable latent fault model includes: Preset target parameters, wherein the target parameters at least include arc characteristic voltage, arc characteristic resistance and time constant; Through the first analysis strategy, a relationship between a target parameter and waveform characteristics of a plurality of first fault simulation waveforms is established.

4. The method for simulating latent fault of medium voltage distribution cable according to claim 3, characterized in that: The first analysis strategy includes: Using the control variable method, several groups of parameter conditions are set for all target parameters; The first fault simulation waveform under different parameter combinations is obtained according to the plurality of groups of parameter conditions.

5. The method for simulating latent fault of medium voltage distribution cable according to claim 4, characterized in that: The establishment of a target cable latent fault model based on an arc model comprises: The part of the water tree and electric tree channel where arc discharge does not occur is equivalent to a constant resistance; Connecting the constant resistor in series with the arc model; The whole series is defined as the target cable latent fault model.

6. The method for simulating latent fault of medium voltage distribution cable according to claim 5, characterized in that: The control variable method is used to set several groups of parameter conditions for all target parameters, including: Select any first target parameter as a variable parameter, and the other target parameters as constant parameters; Grouping the first target parameters to set a plurality of groups of first target parameters; Each group of first target parameters forms several groups of parameter conditions with the remaining target parameters; The first fault simulation waveform under different parameter combinations is obtained according to the plurality of groups of parameter conditions.

7. The method for simulating latent fault of medium voltage distribution cable according to claim 6, characterized in that: The arc model is a mathematical model about time constant, arc static equivalent conductance and arc instantaneous conductance.

8. A system for simulating latent faults of medium voltage distribution cables, characterized in that: include: A model building module, used to build a target cable latent fault model based on an arc model; A simulation module, used to establish a first simulation model according to the target cable latent fault model, and obtain a first fault simulation waveform; An analysis module, used for obtaining the relationship between the target parameter and the fault characteristics in the target cable latent fault model according to the first fault simulation waveform; The model determination module is used to obtain the optimal target parameters to determine the final target cable latent fault model.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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

Images