Resistance grounding system grounding fault arc simulation method and device

Abstract

The embodiment of the invention discloses a resistance grounding system grounding fault arc simulation method and device. The method comprises the following steps: establishing a simulation model of a resistance grounding system grounding fault arc generation process; simulating an arc generation process based on the simulation model, continuously reducing a simulation resistance value of a neutral point resistor of the resistance grounding system during simulation until a combustion mode of an arc is changed into a steady-state arc mode, and determining the simulation resistance value at the moment as a target resistance value; and setting the actual resistance value of a neutral point resistor of the resistance grounding system as the target resistance value, so that the electric arc burns in a steady-state electric arc mode when a grounding fault occurs. According to the invention, the positioning efficiency of the grounding fault of the resistance grounding system can be improved.

Description

Technical Field

[0001] The invention relates to a resistance grounding system, and in particular to a method and a device for simulating a grounding fault arc in a resistance grounding system. Background Art

[0002] The resistance grounding system refers to the method in which the neutral point of the power system is grounded through a resistor. The neutral point is the common connection point of the windings of three-phase power equipment (such as transformers and generators). When the three phases are operating symmetrically, the neutral point potential is zero. When it is grounded through a resistor, it becomes the reference point for the system grounding. The resistance grounding system is divided into a high resistance grounding system and a low resistance grounding system according to the size of the resistor. The resistors in the high resistance grounding system have a large resistance value, which limits the fault current to several amperes (such as 5-10A), allowing the system to continue to operate for a short period of time during a single-phase grounding fault, thereby improving the continuity of power supply. The resistors in the low resistance grounding system have a small resistance value and a large fault current (such as tens to hundreds of amperes), which is designed to quickly trigger the protection device to cut off the fault, sacrificing some continuity to ensure equipment safety.

[0003] There are two burning states of arc when a ground fault occurs in a resistance grounding system, transient arc mode and steady-state arc mode. Transient arc mode refers to the arc burning state dominated by high-frequency transient current, characterized by violent fluctuations in current amplitude, rapid expansion and contraction of the arc channel, and accompanied by significant electromagnetic transient processes. In this mode, the arc may quickly self-extinguish due to current zero crossing or a sudden drop in the conductivity of the plasma channel (usually lasting from several milliseconds to tens of milliseconds). However, the randomness and short-term nature of the transient arc may cause the grounding protection device to be unable to reliably detect the fault signal and cannot be activated correctly. The steady-state arc mode is a state in which the arc enters a continuous and stable burning state, its current waveform approaches the power frequency sine, and the arc channel parameters (such as temperature, radius, resistance) show periodic quasi-steady-state changes. The current amplitude of the steady-state arc is stable and easy to detect, providing a reliable fault feature quantity for the grounding protection device. The stable current characteristics of the steady-state arc significantly improve the fault current signal-to-noise ratio, enabling the grounding protection device to accurately identify and correctly activate. In addition, the amplitude and phase characteristics of the steady-state current can be used for rapid fault location.

[0004] Based on the characteristics of steady-state arcs, in scenarios where accurate fault location is required, it is possible to consider converting transient arcs into steady-state arcs when a ground fault occurs. However, how to effectively convert the arc of a ground fault from a transient arc to a steady-state arc to quickly locate the ground fault is a problem that the existing technology needs to solve.

[0005] This section is intended to provide a background or context to the embodiments of the invention recited in the claims. No admission is made that the description herein is prior art by inclusion in this section. Summary of the invention

[0006] In order to solve at least one of the technical problems in the above-mentioned background art, the present invention proposes a method and device for simulating a grounding fault arc in a resistance grounding system.

[0007] To achieve the above object, according to one aspect of the present invention, there is provided a method for simulating a grounding fault arc in a resistance grounding system, the method comprising:

[0008] Establishing a simulation model of the grounding fault arc occurrence process in the resistance grounding system;

[0009] Based on the simulation model, simulating the arc occurrence process, and continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system during the simulation until the combustion mode of the arc changes to a steady-state arc mode, and determining the simulated resistance value at this time as the target resistance value;

[0010] Setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value so that the arc burns in a steady-state arc mode when a grounding fault occurs.

[0011] Optionally, the continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system during the simulation until the combustion mode of the arc changes to a steady-state arc mode includes:

[0012] Determining whether the combustion mode of the arc changes to a steady-state arc mode by performing waveform analysis on at least one of the simulated arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal.

[0013] Optionally, the determining whether the combustion mode of the arc changes to a steady-state arc mode by performing waveform analysis on at least one of the simulated arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal includes:

[0014] If the waveforms of the arc current signal, arc voltage signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal exhibit the characteristics of power frequency sine waves in multiple power frequency cycles, and the waveform of the arc resistance signal exhibits periodic changes synchronized with the power frequency in multiple power frequency cycles, it is determined that the combustion mode has changed to a steady-state arc mode.

[0015] Optionally, the establishing a simulation model of the grounding fault arc occurrence process in the resistance grounding system includes:

[0016] Establishing the simulation model based on a cylindrical symmetric convective stable arc model.

[0017] Optionally, the neutral resistor of the resistance grounding system is a variable resistor;

[0018] Setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value includes:

[0019] Adjusting the actual resistance value of the variable resistor to the target resistance value.

[0020] Optionally, the method further includes:

[0021] After completing the grounding fault location, setting the actual resistance value of the neutral resistor of the resistance grounding system to a preset high resistance value to extinguish the arc.

[0022] Optionally, the resistance grounding system is a high-resistance grounding system;

[0023] Setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value so that when a grounding fault occurs, the arc burns in a steady-state arc mode includes:

[0024] When a grounding fault occurs, adjusting the resistance value of the neutral resistor of the high-resistance grounding system from the initial resistance value to the target resistance value to change the burning mode of the arc to a steady-state arc mode;

[0025] The method further includes:

[0026] After completing the grounding fault location, restoring the actual resistance value of the neutral resistor of the high-resistance grounding system to the initial resistance value to extinguish the arc.

[0027] To achieve the above object, according to another aspect of the present invention, there is provided an apparatus for simulating an arc in a grounding fault of a resistance grounding system, the apparatus includes:

[0028] A simulation model establishment unit for establishing a simulation model of the occurrence process of an arc in a grounding fault of a resistance grounding system;

[0029] A target resistance value determination unit for simulating the arc occurrence process based on the simulation model, continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system during the simulation until the burning mode of the arc becomes a steady-state arc mode, and determining the simulated resistance value at this time as the target resistance value;

[0030] A resistor resistance value setting unit for setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value so that when a grounding fault occurs, the arc burns in a steady-state arc mode.

[0031] To achieve the above object, according to another aspect of the present invention, there is also provided a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor implements the steps of the above method for simulating an arc in a grounding fault of a resistance grounding system when executing the computer program.

[0032] To achieve the above object, according to another aspect of the present invention, there is also provided a computer-readable storage medium, on which a computer program / instructions are stored, and when the computer program / instructions are executed by a processor, the steps of the above-mentioned grounding fault arc simulation method for a resistance grounding system are implemented.

[0033] The beneficial effects of the present invention are as follows:

[0034] The present invention establishes a simulation model of the grounding fault arc generation process in a resistance grounding system, and then based on the model simulation, determines the target resistance value of the neutral point resistor required to change the combustion mode of the arc into a steady-state arc mode. Furthermore, in practical applications, the resistance value of the neutral point resistor can be set to the target resistance value obtained through the model simulation, thereby converting the arc of the grounding fault into a steady-state arc mode. Then, based on the characteristics of the steady-state arc mode, rapid positioning of the grounding fault can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings:

[0036] Figure 1 is a flowchart of the grounding fault arc simulation method for a resistance grounding system according to an embodiment of the present invention;

[0037] Figure 2 is a flowchart of determining whether the combustion mode of the arc changes to a steady-state arc mode according to an embodiment of the present invention;

[0038] Figure 3 is a structural block diagram of the grounding fault arc simulation device for a resistance grounding system according to an embodiment of the present invention;

[0039] Figure 4 is a structural block diagram of the target resistance value determination unit according to an embodiment of the present invention;

[0040] Figure 5 is a schematic diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0042] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0043] It should be noted that the terms "including" and "having" and any variations thereof in the description and claims of the present invention and the above-mentioned accompanying drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0044] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The following will detail the present invention with reference to the accompanying drawings and in conjunction with the embodiments.

[0045] The present invention studies the results of metal ground faults and arcing ground faults occurring in a 35 kV overhead distribution network with high or low neutral grounding resistance. The present invention uses self-developed software to simulate a cylindrical symmetric channel model for a stable vertical arc (maintained by rising convective airflows). Through the created computer arc model, oscillograms of phase-to-ground fault current and breakdown voltage are obtained, as well as oscillograms of the temperature evolution, impedance, and arc radius of the central channel. Based on the obtained results, the efficiency of the neutral grounding resistance during the ground fault is analyzed. The results show that considering the arc equation can lead to the rapid self-extinction of the arc. In addition, the mathematical model of the arc shows that increasing the active fault current component to a certain value helps to transform the transient arc combustion mode into a steady state mode. The obtained results are applied to prove the actual incidence of arc self-extinction in phase-to-ground faults (including during repeated breakdowns). For steady-state arc phase-to-ground faults, it is necessary to use anti-neutral grounding to quickly locate the fault.

[0046] The research object of the present invention is a 35 kV resistance grounded system. In the substation, two 25 MVA 110 / 35 / 10 kV power transformers are installed. Three ACSR overhead lines with a cross-sectional area of 50 to 120 square millimeters start from the switchgear. The 35 kV line supplies power to five 35 / 10(6) kV substations. In the computer model, the external 110 kV network is represented by an inductor-resistor equivalent electromotive force (calculated based on the known short-circuit current ratio of the 110 kV substation bus). For the line parameters, data on the support structure and the height of the conductor phase suspension are used. It should be noted that in normal operation (without a grounding resistor), the neutral point voltage of the 35 kV network is not zero, so the adopted 35 kV overhead line is a non-transposed structure. The total length of the 35 kV line from the bus section is approximately 75 km. When setting the transformer parameters (short-circuit voltage, short-circuit loss, rated power, and voltage), passport data from the manufacturer are used.

[0047] The present invention uses the arc equation for modeling and analyzes the efficiency of resistance grounding when a phase-to-ground arc fault occurs. Reactance grounding is usually applied to industrial, urban cable, and rural overhead distribution lines. When an arc grounding fault occurs in such a network, not only capacitive current is generated at the fault point, but also resistive current. This sometimes allows adjusting the selectivity of the relay and limiting the arc overvoltage in the case of possible repeated breakdowns.

[0048] Usually, two types of resistance neutral grounding are used in 6 - 35 kV networks: low resistance and high resistance. Low resistance neutral grounding means that the ground fault current at the fault point is large enough (>10 A) to activate the ground fault protection without delay (or with a negligible delay). That is, using a low-impedance resistor requires disconnecting the network (or an appropriate connection). High resistance neutral grounding is used in cases where uninterrupted operation of the faulty network is required (without disconnecting the power supply). It should be noted that the phase-to-ground arc current at the fault point is usually less than 10 A. In this operating mode, the ground fault protection usually only issues an alarm and is rarely used for selectively disconnecting the faulty feeder. Consider an example of a 35 kV high resistance grounded system. The resistance is R = 275 kΩ, and the ground fault current in the network is approximately I arc = 10 A.

[0049] The present invention simulates the metal ground fault that occurs in the high resistance grounded system. The simulation results show that in the initial stage of the fault, the arc current surges to I arc max = 150 A, and then the steady-state current drops to I arc= 10 A. After the transient phenomena caused by the ground fault have decayed, the neutral-to-ground voltage is consistent with the phase-to-ground voltage. It can be inferred from the simulation that in the presence of a high-resistance neutral point, the decay of the high-frequency fault current and the phase-neutral voltage component is more rapid.

[0050] The present invention simulates the arcing ground fault occurring in a high-resistance grounding system. The simulation reveals that, compared to the case of an isolated neutral point system, the implementation of the arc equation leads to relatively rapid self-extinction. Additionally, it is also found that the arcing overvoltage occurring in a resistance grounding system is smaller than that in an isolated neutral point system. The arcing overvoltage ratio in the resistance grounding system is K = 2.7. In the resistance grounding system, the neutral-to-ground voltage rapidly decreases. This is the main advantage of the considered neutral grounding method because possible heavy strikes must occur when the neutral-to-ground voltage is close to zero. Therefore, the heavy strike overvoltage ratio will be reduced.

[0051] Through the simulation of the high-resistance grounding system, it is found that the high-resistance grounding system can effectively promote the self-extinction of the arc.

[0052] In addition, the present invention also simulates the arcing ground fault occurring in a low-resistance grounding system.

[0053] The fact of the fault occurrence and arc extinction does not allow the detection of weak points in the network. This fact is particularly important when accidents tend to occur frequently. In this case, the steady-state arc can help correctly activate the ground fault protection. By knowing the target resistance value installed on the neutral point (which can ensure the steady-state arc mode), an adjusted resistor (with a short-time reduced resistance) can be installed in the network neutral point to promote the selective operation of the relay protection device. The computer modeling of the arc shows that for this network, when the resistance value R of the neutral point resistor n is less than 0.9 kΩ, a resistance change from the high-resistance to the low-resistance range can be achieved.

[0054] Through the simulation, it is found that by increasing the effective component value of the fault current, it helps to convert the transient arc mode to the steady-state mode. The effective value of the steady-state phase-to-ground fault current is Iarc = 23 A. This value is 3.8 times the effective value of the capacitive current when the neutral point is isolated (this fact is very consistent with the results of the previous experimental studies). In other words, in order to ensure the steady-state arc mode in a network with a reference capacitive current, an effective current at least 4 times the capacitive current must be "added" at the fault point (by introducing a resistance in the neutral point). Through the simulation, it is found that by reducing the resistance value (R n = 0.9 kΩ), the effective component value of the fault current can be increased, which helps to convert the transient arc mode to the steady-state mode.

[0055] For a low-resistance grounded system, the arc overvoltage is lower than that of a high-resistance grounded system. In a low-resistance network, the arc overvoltage does not exceed K ov = 2.5. The slight voltage drop caused by the fault is due to the faster decay of the high-frequency current component.

[0056] The following conclusions can be drawn from the above simulation studies:

[0057] 1. Considering the arc equation leads to the rapid self-extinction of the arc. In addition, the study also shows that by increasing the effective component of the arc current (by reducing the neutral point resistance) to a certain value, it helps to transform the transient arc combustion mode into a steady state mode. This can be used to quickly locate the fault point.

[0058] 2. In a high-resistance grounded system, the neutral point-to-ground voltage drops rapidly after the arc self-extinguishes. This is the main advantage of this neutral point grounding mode because possible re-strikes will occur when the neutral point-to-ground voltage is close to zero. Therefore, the re-strike overvoltage ratio will be significantly reduced.

[0059] 3. Reducing the high resistance of the system neutral point (i.e., less than 0.9 kΩ) and converting it to the low-resistance range is very beneficial for the selective operation of relay protection and automation devices. In this case, steady-state arc combustion is ensured.

[0060] Based on the simulation results, the present invention proposes that in scenarios where precise fault location is required, the transient arc can be transformed into a steady-state arc when a grounding fault occurs to achieve rapid fault location. However, how to effectively transform the arc of the grounding fault from a transient arc to a steady-state arc to achieve rapid location of the grounding fault is a problem that needs to be solved by the prior art. The present invention proposes a solution to this problem.

[0061] Figure 1 is a flowchart of the method for simulating the grounding fault arc of a resistance grounded system according to an embodiment of the present invention. As Figure 1 shown, in an embodiment of the present invention, the method for simulating the grounding fault arc of the resistance grounded system of the present invention includes steps S1 to S3.

[0062] Step S1, establish a simulation model of the grounding fault arc occurrence process of the resistance grounded system.

[0063] In the present invention, first, a simulation model of the grounding fault arc occurrence process of the resistance grounded system is established. This simulation model is based on the electrical characteristics of the resistance grounded system and combines the mathematical model of the arc to accurately describe the dynamic behavior of the grounding fault arc.

[0064] Specifically, the simulation model of the present invention can adopt a cylindrically symmetric convective stable arc model, which can more accurately simulate the thermodynamics characteristics of the arc, the change of conductivity, and the energy exchange process between the arc and the surrounding environment. At the same time, considering the actual operation of the resistance grounded system, the simulation model includes key factors such as the system neutral grounding resistance, grid parameters, fault current characteristics, and arc equivalent resistance.

[0065] Through this simulation model, the present invention can analyze the formation, development, and combustion mode change process of the grounding fault arc under different working conditions, providing a theoretical basis for the subsequent determination and optimization of the target resistance value.

[0066] Step S2: Based on the simulation model, simulate the arc generation process. During the simulation, continuously reduce the simulated resistance value of the neutral resistor of the resistance grounded system until the combustion mode of the arc changes to the steady-state arc mode, and determine the simulated resistance value at this time as the target resistance value.

[0067] In an embodiment of the present invention, the target resistance value can be a resistance value range, and the present invention determines the resistance value range of the neutral resistor that can maintain the steady-state arc mode through simulation.

[0068] Based on the established simulation model, the present invention uses the model to simulate the grounding fault arc generation process of the resistance grounded system. During the simulation process, gradually reduce the simulated resistance value of the neutral resistor and observe the change of the arc combustion mode.

[0069] In the specific implementation process, during the simulation process, judge whether the arc changes from the random combustion mode to the steady-state arc mode by monitoring the waveform characteristics of simulation signals such as the arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal. When it is monitored that the arc current, voltage, and resistance signals show stable power frequency sine wave characteristics within multiple power frequency cycles, and the waveform of the arc resistance signal changes periodically in synchronization with the power frequency, it can be considered that the arc has entered the steady-state combustion mode.

[0070] At this time, the simulated resistance value of the corresponding neutral resistor is the critical value to achieve the steady-state arc mode, that is, the target resistance value. The target resistance value can be a specific value or a resistance value within a certain range to ensure that the conversion of the arc combustion mode can be stably maintained during the actual operation process.

[0071] Step S3: Set the actual resistance value of the neutral resistor of the resistance grounded system to the target resistance value so that the arc burns in the steady-state arc mode when a grounding fault occurs.

[0072] After determining the target resistance value, the present invention adjusts the actual resistance value of the neutral resistor in the resistance grounding system to the target resistance value to ensure that when a grounding fault occurs, the arc can burn in a steady-state arc mode.

[0073] In the specific implementation process, if the neutral resistor is an adjustable resistor, its resistance value can be adjusted to the target value automatically or manually; if a fixed-resistance resistor is used, its resistance value can be made to match the target resistance value obtained through simulation by reasonable selection and design.

[0074] In addition, to ensure the safety of power grid operation and the recoverability of the system, the present invention also provides a dynamic adjustment strategy. After completing the grounding fault location, the actual resistance value of the neutral resistor can be restored to a preset high resistance value so that the arc can be quickly extinguished, reducing the impact on the system and improving the stability and safety of system operation.

[0075] In summary, the present invention realizes the control of the grounding fault arc mode and the optimization of fault location by establishing a simulation model, simulating the arc combustion process and determining the target resistance value, and dynamically adjusting the resistance value of the neutral resistor, improving the safety of the system and the efficiency of fault handling.

[0076] As Figure 2 shown, in an embodiment of the present invention, in the above step S2, when simulating, continuously reducing the simulated resistance value of the neutral resistor in the resistance grounding system until the combustion mode of the arc becomes a steady-state arc mode includes step S201.

[0077] Step S201, determining whether the combustion mode of the arc has become a steady-state arc mode by performing waveform analysis on at least one of the arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal obtained through simulation.

[0078] In the simulation process of the present invention, in order to accurately identify the change in the arc combustion mode, it is necessary to monitor the key electrical signals of the arc in real time and perform waveform analysis. This step determines whether the arc has entered the steady-state combustion mode by analyzing at least one of the arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal obtained through simulation.

[0079] In an embodiment of the present invention, the above step S201 of determining whether the combustion mode of the arc has become a steady-state arc mode by performing waveform analysis on at least one of the arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal obtained through simulation includes:

[0080] If the waveforms of the arc current signal, arc voltage signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal exhibit the characteristics of power-frequency sine waves in multiple power-frequency cycles, and the waveform of the arc resistance signal exhibits periodic changes synchronized with the power frequency in multiple power-frequency cycles, then it is determined that the combustion mode has changed to the steady-state arc mode.

[0081] In addition to the above basic solution, the present invention can also adopt various solutions based on different signal characteristics and analysis methods to determine whether the arc has entered the steady-state combustion mode.

[0082] In an embodiment of the present invention, the present invention can calculate the root mean square (RMS) values of the arc current, arc voltage, and arc resistance signals. If the rate of change of the root mean square in multiple consecutive power-frequency cycles is less than a preset threshold (such as 1%), it indicates that the arc has entered the steady-state combustion mode.

[0083] In an embodiment of the present invention, the present invention can calculate the phase difference between the arc current and the arc voltage. If the phase difference remains stable in multiple cycles (such as the change is less than 2°), it indicates that the arc has entered the steady-state mode.

[0084] In an embodiment of the present invention, the present invention can perform frequency-domain analysis on the arc current and arc voltage using the fast Fourier transform (FFT). If the main frequency component is located at 50 Hz or 60 Hz (corresponding to the power grid power frequency), and the harmonic content (such as the harmonic components of the 3rd order and above) is lower than the set threshold (such as the total harmonic distortion rate THD is less than 10%), it is determined that the arc is in the steady-state combustion mode.

[0085] In an embodiment of the present invention, the present invention can calculate the rate of change of the arc resistance in different power-frequency cycles. If the rate of change is less than the set threshold (such as 5%), and the waveform of the arc resistance exhibits stable periodic fluctuations, it indicates that the arc has entered the steady-state mode.

[0086] The above-mentioned various solutions can be used in different embodiments of the present invention to meet the accurate determination requirements for the steady-state arc mode in different application scenarios. By combining waveform analysis, resistance change trend analysis, spectrum analysis, and other signal processing technologies, the present invention can reliably determine whether the arc has entered the steady-state combustion mode, thereby determining the appropriate target resistance value and improving the safety and stability of the resistance grounding system.

[0087] In an embodiment of the present invention, establishing the simulation model of the grounding fault arc occurrence process of the resistance grounding system in step S1 includes:

[0088] Establishing the simulation model based on the cylindrical symmetric convective steady arc model.

[0089] In the present invention, the adopted cylindrically symmetric convective steady arc model is based on the arc model proposed by V. Gavrikov et al. in the literature "Mathematical modeling of AC open air arc" (Energy, no. 8, pp. 27 - 32, 1984). This model describes the physical characteristics of an open air arc in an AC environment through mathematical methods, and takes into account the thermodynamics characteristics and conductivity variation law of the arc. The present invention establishes a simulation model of the grounding fault arc in a resistance grounded system based on this model to simulate the arc combustion process, and then determines the target resistance value of the neutral point resistor that can adjust the arc combustion mode to the steady arc mode, thereby improving the positioning accuracy and detection reliability of the grounding fault.

[0090] In an embodiment of the present invention, the neutral point resistor of the resistance grounded system is a variable resistor;

[0091] The setting the actual resistance value of the neutral point resistor of the resistance grounded system to the target resistance value in the above step S3 includes:

[0092] Adjusting the actual resistance value of the variable resistor to the target resistance value.

[0093] In an embodiment of the present invention, the method of the present invention further includes:

[0094] After completing the grounding fault location, setting the actual resistance value of the neutral point resistor of the resistance grounded system to a preset high resistance value to extinguish the arc.

[0095] During the occurrence of a fault in the present invention, the system will automatically adjust the neutral point resistance value according to the arc combustion mode to make it reach the target resistance value required for the aforementioned steady arc mode, so as to analyze the arc characteristics and complete the fault location. After the fault location is completed, the system will readjust the neutral point resistance value to restore it to the preset high resistance value, thereby effectively increasing the impedance of the grounding fault loop, reducing the arc current, and extinguishing the arc.

[0096] In a resistance grounded system, the maintenance of the arc depends on the magnitude of the arc current. When the resistance value of the neutral point resistor is low, the arc current is large, which may cause the arc to burn continuously. By restoring the neutral point resistance value to the preset high resistance value in the present invention, the arc current can be significantly reduced, making it lower than the holding current threshold (i.e., the minimum current required for the arc not to burn continuously), and finally causing the arc to extinguish naturally. This process of the present invention can effectively prevent insulation damage, power grid instability, and potential equipment damage risks caused by long - time arc combustion.

[0097] In an embodiment of the present invention, the preset high resistance value can refer to the resistance value of the resistor in the current high-resistance grounding system. For example, in a 35 kV high-resistance grounding system, the resistance value R of the resistor is 275 kΩ.

[0098] In an embodiment of the present invention, the resistance grounding system is a high-resistance grounding system. The step S3 of setting the actual resistance value of the neutral point resistor of the resistance grounding system to the target resistance value so that the arc burns in a steady-state arc mode during a grounding fault includes:

[0099] During a grounding fault, adjusting the resistance value of the neutral point resistor of the high-resistance grounding system from the initial resistance value to the target resistance value to change the combustion mode of the arc to a steady-state arc mode;

[0100] In an embodiment of the present invention, the method of the present invention further includes:

[0101] After completing the grounding fault location, restoring the actual resistance value of the neutral point resistor of the high-resistance grounding system to the initial resistance value to extinguish the arc.

[0102] In an embodiment of the present invention, in order to optimize the arc control of the high-resistance grounding system during the occurrence and handling of grounding faults, the present invention proposes a method for dynamically adjusting the resistance value of the neutral point resistor. This method adjusts in two stages, that is, adjusting to the target resistance value during the fault period and restoring to the initial resistance value after the fault handling, to ensure the controllable combustion and final extinguishment of the arc, thereby improving the safety and stability of the system.

[0103] In a resistance grounding system (especially a high-resistance grounding system), when a single-phase grounding fault occurs, the initial resistance value of the neutral point resistor is relatively high, resulting in the fault arc may exhibit intermittent combustion or an unstable state, which is not conducive to fault feature extraction and accurate location. In order to ensure that the arc can burn stably for grounding fault analysis and location, the present invention monitors electrical quantities such as the neutral point - ground voltage signal, the fault phase - ground voltage signal, and the arc current signal to determine whether a single-phase grounding fault has occurred in the system. When a fault occurs, the system starts the arc combustion mode control mechanism, and adjusts the resistance value of the neutral point resistor of the high-resistance grounding system from the initial high resistance value to the target resistance value, so that the arc combustion mode changes from the transient arc mode to the steady-state arc mode. The setting of the target resistance value is based on simulation analysis to ensure that the arc current is sufficient to maintain the stable combustion of the arc, but does not overly enhance the arc intensity to avoid equipment damage.

[0104] The adjustment method of the target resistance value can adopt an adjustable resistor array to automatically switch the resistance value according to the arc current characteristics, or also adopt electronic control to adjust the resistance, and dynamically adjust the neutral point resistance value through a real-time feedback system.

[0105] The present invention can determine the fault point and record the fault information through the fault detection and location algorithm of the power system, ensure that the diagnostic data of the ground fault has been stored, and prepare to take arc extinguishing measures. After completing the ground fault location, in order to extinguish the arc as soon as possible and reduce the damage of the arc to the power equipment and insulation system, the present invention adjusts the resistance value of the neutral point resistor back to the initial high resistance value. Since the neutral point resistance value increases, the impedance of the fault circuit increases, resulting in a rapid decrease in the arc current until it is lower than the holding current threshold (i.e., the minimum current at which the arc cannot continue to burn). As the current decreases, the arc extinguishes, avoiding equipment damage, insulation deterioration, or secondary faults caused by continuous burning.

[0106] The method of the present invention can flexibly adjust the target resistance value and the initial resistance value according to the requirements of different power systems, and is applicable to high-resistance grounding systems with voltage levels of 35 kV, 110 kV, 220 kV and above.

[0107] As can be seen from the above embodiments, the method of the present invention has at least achieved the following beneficial effects:

[0108] 1. Optimize the arc combustion mode of the ground fault.

[0109] The present invention determines the target resistance value of the neutral point resistor through simulation analysis, enables the ground fault arc to burn stably, avoids the irregular fluctuations of the transient arc, and improves the detection accuracy.

[0110] 2. Improve the efficiency of ground fault location.

[0111] The present invention adopts the steady-state arc mode, making the arc current and voltage characteristics more stable, facilitating the extraction of fault signals, and achieving fast and accurate fault location.

[0112] 3. Adaptively adjust the neutral point resistance value.

[0113] The present invention adjusts to the target resistance value through the variable resistor during the occurrence of the fault and restores to the initial high resistance value after the fault location, ensuring the safe and stable operation of the system.

[0114] 4. Simulation optimization improves applicability.

[0115] The present invention adopts the cylindrical symmetric convective stable arc model for simulation analysis, making the method applicable to different types of resistance grounding systems and enhancing the generality and adaptability of the scheme.

[0116] 5. Reduce the misjudgment rate.

[0117] The present invention analyzes the signal waveforms such as current, voltage, and arc resistance, judges the arc mode in multiple dimensions, avoids misjudgment caused by a single signal, and improves the reliability of fault recognition.

[0118] 6. Enhance the safety of the high-resistance grounding system.

[0119] After the fault location is completed, the present invention restores the high resistance value, promotes the rapid extinction of the arc, ensures the normal operation of the system, and avoids potential power grid safety hazards that may be brought by continuous arcing.

[0120] 7. Applicable to different resistance grounding systems.

[0121] The method of the present invention can be applied to a high-resistance grounding system, and a suitable resistance adjustment strategy is determined through simulation to meet the requirements of different systems.

[0122] Through simulation optimization, resistance adaptive adjustment, and signal feature analysis, the present invention realizes more efficient and accurate grounding fault detection and location, while ensuring the system safety and applicability.

[0123] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0124] Based on the same inventive concept, the embodiment of the present invention also provides a grounding fault arc simulation device for a resistance grounding system, which can be used to implement the grounding fault arc simulation method for the resistance grounding system described in the above embodiment, as described in the following embodiment. Since the principle of solving problems by the grounding fault arc simulation device for the resistance grounding system is similar to that of the grounding fault arc simulation method for the resistance grounding system, the embodiment of the grounding fault arc simulation device for the resistance grounding system can refer to the embodiment of the grounding fault arc simulation method for the resistance grounding system, and the repeated parts will not be described again. As used below, the term "unit" or "module" can be a combination of software and / or hardware that can implement a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0125] Figure 3 is the structural block diagram of the grounding fault arc simulation device for the resistance grounding system in the embodiment of the present invention, as Figure 3 shown, in an embodiment of the present invention, the grounding fault arc simulation device for the resistance grounding system of the present invention includes:

[0126] A simulation model establishment unit 1, configured to establish a simulation model of the grounding fault arc occurrence process of the resistance grounding system;

[0127] A target resistance value determination unit 2, configured to simulate the arc occurrence process based on the simulation model, continuously reduce the simulated resistance value of the neutral point resistor of the resistance grounding system during the simulation until the combustion mode of the arc becomes a steady-state arc mode, and determine the simulated resistance value at this time as the target resistance value;

[0128] A resistor value setting unit 3 is configured to set the actual resistance value of the neutral point resistor of the resistor grounding system to the target resistance value, so that when a grounding fault occurs, the arc burns in a steady-state arc mode.

[0129] As Figure 4 shown, in an embodiment of the present invention, the target resistance value determination unit 2 includes:

[0130] A waveform analysis module 201 is configured to determine whether the combustion mode of the arc changes to a steady-state arc mode by performing waveform analysis on at least one of the simulated arc current signal, arc voltage signal, arc resistance signal, neutral point-to-ground voltage signal, and phase-to-ground voltage signal.

[0131] In an embodiment of the present invention, the waveform analysis module 201 is specifically configured to determine that the combustion mode changes to a steady-state arc mode if the waveforms of the arc current signal, arc voltage signal, neutral point-to-ground voltage signal, and phase-to-ground voltage signal exhibit the characteristics of a power frequency sine wave in multiple power frequency cycles, and the waveform of the arc resistance signal exhibits a periodic change synchronized with the power frequency in multiple power frequency cycles.

[0132] In an embodiment of the present invention, the simulation model establishment unit 1 is specifically configured to establish the simulation model based on a cylindrical symmetric convective steady arc model.

[0133] In an embodiment of the present invention, the neutral point resistor of the resistor grounding system is a variable resistor.

[0134] In an embodiment of the present invention, the resistor value setting unit 3 includes:

[0135] A variable resistor adjustment module is configured to adjust the actual resistance value of the variable resistor to the target resistance value.

[0136] In an embodiment of the present invention, the resistor grounding system grounding fault arc simulation device of the present invention further includes:

[0137] A high resistance value setting unit is configured to set the actual resistance value of the neutral point resistor of the resistor grounding system to a preset high resistance value after the grounding fault is located, so as to extinguish the arc.

[0138] In an embodiment of the present invention, the resistor grounding system is a high-resistance grounding system. In an embodiment of the present invention, the resistor value setting unit 3 includes:

[0139] A high-resistance grounding system resistance value setting module is configured to adjust the resistance value of the neutral point resistor of the high-resistance grounding system from an initial resistance value to the target resistance value when a grounding fault occurs, so as to change the combustion mode of the arc to a steady-state arc mode.

[0140] In one embodiment of the present invention, the grounding fault arc simulation device of the resistance grounding system of the present invention further includes:

[0141] An initial resistance value recovery unit, configured to restore the actual resistance value of the neutral point resistor of the high-resistance grounding system to the initial resistance value after the grounding fault is located, so as to extinguish the arc.

[0142] To achieve the above object, according to another aspect of the present application, a computer device is further provided. As Figure 5 shown, the computer device includes a memory, a processor, a communication interface, and a communication bus. A computer program that can run on the processor is stored on the memory. When the processor executes the computer program, the steps in the method of the above embodiment are implemented.

[0143] The processor may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. chips, or a combination of the above various types of chips.

[0144] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and units, such as the corresponding program units in the above method embodiments of the present invention. The processor executes various functional applications and data processing of the work by running the non-transitory software programs, instructions, and modules stored in the memory, that is, the method in the above method embodiments is implemented.

[0145] The memory may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created by the processor, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely set relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0146] The one or more units are stored in the memory and, when executed by the processor, perform the method in the above embodiments.

[0147] Specific details of the above computer device can be understood by referring to the corresponding relevant descriptions and effects in the above embodiments, and will not be elaborated here.

[0148] To achieve the above object, according to another aspect of the present application, there is also provided a computer-readable storage medium storing a computer program, which when executed in a computer processor, implements the steps in the above method for simulating ground fault arcs in a resistance grounded system. Those skilled in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.

[0149] To achieve the above object, according to another aspect of the present application, there is also provided a computer program product including a computer program / instructions, which when executed by a processor, implements the steps of the above method for simulating ground fault arcs in a resistance grounded system.

[0150] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. Optionally, they can be implemented by program code executable by the computing device, so that they can be stored in a storage device and executed by the computing device, or they can be separately made into individual integrated circuit modules, or multiple modules or steps among them can be made into a single integrated circuit module to implement. In this way, the present invention is not limited to any specific combination of hardware and software.

[0151] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for simulating an arc fault in a resistance grounded system, characterized in that Comprising: Establishing a simulation model for the grounding fault arc occurrence process of a resistance grounding system; Based on the simulation model, simulating the arc occurrence process. During the simulation, continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system until the combustion mode of the arc changes to a steady-state arc mode, and determining the simulated resistance value at this time as the target resistance value; Setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value so that the arc burns in a steady-state arc mode when a grounding fault occurs.

2. The method for simulating an earth fault arc in a resistance grounding system according to claim 1, wherein The continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system during the simulation until the combustion mode of the arc changes to a steady-state arc mode includes: Determining whether the combustion mode of the arc changes to a steady-state arc mode by performing waveform analysis on at least one of the simulated arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal.

3. The method for simulating an earth fault arc in a resistance grounded system according to claim 2, wherein The determining whether the combustion mode of the arc changes to a steady-state arc mode by performing waveform analysis on at least one of the simulated arc current signal, arc voltage signal, arc resistance signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal includes: If the waveforms of the arc current signal, arc voltage signal, neutral-to-ground voltage signal, and phase-to-ground voltage signal exhibit the characteristics of power frequency sine waves in multiple power frequency cycles, and the waveform of the arc resistance signal exhibits periodic changes synchronized with the power frequency in multiple power frequency cycles, then determining that the combustion mode changes to a steady-state arc mode.

4. The method for simulating a ground fault arc in a resistance grounding system according to claim 1, wherein The establishing a simulation model for the grounding fault arc occurrence process of a resistance grounding system includes: Establishing the simulation model based on the cylindrical symmetric convective steady arc model.

5. The method for simulating a ground fault arc in a resistance grounded system according to claim 1, wherein, The neutral resistor of the resistance grounding system is a variable resistor; The setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value includes: Adjusting the actual resistance value of the variable resistor to the target resistance value.

6. The method for simulating an earth fault arc in a resistance grounding system according to claim 1, characterized in that, The method further includes: After completing the grounding fault location, setting the actual resistance value of the neutral resistor of the resistance grounding system to a preset high resistance value to extinguish the arc.

7. The method for simulating an earth fault arc in a resistance grounding system according to claim 1, wherein The resistance grounding system is a high-resistance grounding system; The setting the actual resistance value of the neutral resistor of the resistance grounding system to the target resistance value so that the arc burns in a steady-state arc mode when a grounding fault occurs includes: When a grounding fault occurs, adjusting the resistance value of the neutral resistor of the high-resistance grounding system from the initial resistance value to the target resistance value to change the combustion mode of the arc to a steady-state arc mode; The method further includes: After completing the grounding fault location, restoring the actual resistance value of the neutral resistor of the high-resistance grounding system to the initial resistance value to extinguish the arc.

8. An arc simulation device for grounding faults in a resistor grounding system, characterized in that, Comprising: A simulation model establishing unit for establishing a simulation model for the grounding fault arc occurrence process of a resistance grounding system; A target resistance value determining unit for simulating the arc occurrence process based on the simulation model. During the simulation, continuously reducing the simulated resistance value of the neutral resistor of the resistance grounding system until the combustion mode of the arc changes to a steady-state arc mode, and determining the simulated resistance value at this time as the target resistance value; A resistor value setting unit is configured to set the actual resistance value of the neutral point resistor of the resistor grounding system to the target resistance value, so that when a grounding fault occurs, the arc burns in a steady-state arc mode.

9. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, 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 / instruction stored thereon, characterized in that, When the computer program / instructions are executed by the processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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