Fault detection method and system for low-voltage distribution line suitable for charging load access

Abstract

The application discloses a low-voltage distribution line fault detection method and system suitable for charging load access, and aims to solve the problem that the traditional method is easy to misjudge the charging impact current and short-time heavy load as line fault only by the single standard of "current overrun". The method comprises the following steps: firstly, constructing a fault detection starting criterion and a fault occurrence detection criterion; acquiring three-phase voltage and current data of a total meter and a charging pile meter according to a first time interval, substituting the data into the fault detection starting criterion, switching to a second time interval for acquiring data when the starting condition is met, substituting the data into the fault occurrence detection criterion, calculating the duration of the fault condition, and judging the fault when the threshold is reached; the application comprehensively utilizes the characteristics of current surge, voltage reduction and fault duration during the fault, considers the influence of electric vehicle charging load and short-time impact load, avoids the risk of misjudging the electric vehicle charging heavy load and instantaneous disturbance as line fault, and improves the accuracy of distribution line fault detection.

Description

Technical Field

[0001] This invention relates to the field of low-voltage power distribution line protection and control technology, specifically to a fault detection method and system for low-voltage power distribution lines suitable for charging load access. Background Technology

[0002] Power distribution lines are a crucial component of the power system. As the "nerve endings" of the power system, they are directly linked to the safety and convenience of electricity use for countless households. Their safe and stable operation is vital for ensuring power supply and socio-economic development. However, power distribution lines have complex structures and operate in variable environments, making them susceptible to harsh natural conditions. They face numerous challenges during operation, including but not limited to natural environmental factors such as extreme weather, geological changes, equipment aging, human sabotage, and load fluctuations. These factors can all trigger line faults, leading to power outages, disrupting normal social production and daily life, and severely impacting the economic benefits of power supply companies and the overall development of power enterprises. Therefore, efficiently and accurately detecting operational faults in power distribution lines and taking timely repair measures are essential measures to ensure power supply security and enhance grid resilience.

[0003] With the continuous connection of various charging loads, such as home charging piles, community charging stations, and commercial fast charging stations, to low-voltage power distribution lines, traditional fault detection methods that rely on overcurrent and leakage protection functions of air switches are increasingly prone to misjudging the normal startup and operation of three-phase fast charging equipment as line faults. The core issue of this misjudgment problem is that traditional detection methods only use "excessive current" as the single criterion for judging line faults, completely ignoring the unique dynamic electrical characteristics of charging loads: three-phase fast charging equipment generates short-term, periodic inrush currents at the moment of startup. Although the peak value of this current is close to the current level when a short circuit fault occurs in the line, its duration is extremely short, and the line voltage fluctuates slightly during this process, while the power factor remains stable at a high level. This is a typical characteristic of "short-term high current and low voltage disturbance". Traditional air switches typically have fixed overcurrent protection thresholds, making it difficult to effectively distinguish between "fault overcurrent" and "charging start-up inrush current." They often trigger tripping the moment the inrush current occurs, which not only causes sudden interruptions in the user's charging process, affecting the charging experience, but also causes the protection device to start and stop frequently, accelerating the wear and tear on internal components and increasing subsequent maintenance costs.

[0004] Traditional detection methods also struggle to accurately identify short-term high loads, easily misdiagnosing them as line faults. Short-term high loads are common in centralized charging stations, commercial complexes, or town charging pile clusters, often caused by concentrated vehicle charging during specific time periods (such as after peak commuting hours), leading to a cumulative load. The current rises briefly but systematically, stabilizing as charging progresses, fundamentally different from the sudden current surges caused by faults. Such misdiagnosis can lead to frequent power outages at charging stations, impacting user travel and station operations. Simultaneously, repeated activation of protection devices generates operational overvoltages, accelerating line aging and increasing maintenance pressure and safety hazards for power supply companies.

[0005] In conclusion, researching and developing accurate and reliable methods and systems for detecting power distribution line faults, in order to distinguish between high currents caused by charging loads and short-term high loads and line faults, is crucial for ensuring the safety of power distribution networks, optimizing charging services, and promoting high-quality development of the power grid. Summary of the Invention

[0006] In view of this, the present invention aims to solve the problem that traditional methods rely solely on the single criterion of "excessive current" for judgment, which easily leads to misjudging charging inrush current and short-term high load as line faults. It provides a fault detection method and system for low-voltage distribution lines with charging load access. By comprehensively utilizing the characteristics of current surge, voltage drop, and fault persistence during a fault, and also considering the influence of electric vehicle charging load and short-term inrush load, it avoids the risk of misjudging large electric vehicle charging load and instantaneous disturbance as line faults, thereby improving the accuracy of distribution line fault detection.

[0007] To achieve the above objectives, the technical solution adopted is as follows:

[0008] The first aspect of this invention discloses a fault detection method for low-voltage distribution lines suitable for charging load access, comprising the following steps: S1, pre-constructing a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred, wherein the fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line, and the fault occurrence detection criterion is constructed based on the three-phase voltage and current data of both the main meter in the low-voltage distribution line and the sub-meters of the charging pile; S2, acquiring the three-phase voltage data and three-phase current data collected at the main meter and the sub-meters of the charging pile in the low-voltage distribution line in real time based on a first time interval; S3, combining the three-phase voltage data and three-phase current data acquired in step S2... S4. Substitute the streaming data into the fault detection start criterion to determine whether the fault detection start condition is met; S5. If the fault detection start condition is met as determined in step S3, then start acquiring the three-phase voltage data and three-phase current data collected from the main meter and charging pile sub-meters in the low-voltage distribution line in real time based on the second time interval; wherein, the second time interval is less than the first time interval; S6. Substitute the three-phase voltage data and three-phase current data of the main meter and charging pile sub-meters acquired in real time in step S4 into the fault occurrence detection criterion to determine whether the fault condition is met; S7. If the fault condition is met, then continue to repeat step S4, and calculate the duration of meeting the fault condition. If the duration reaches the preset fault judgment time threshold, then determine that a fault has occurred in the low-voltage distribution line.

[0009] In this invention, three-phase voltage and current data collected in real time from the main meter and charging pile sub-meters in low-voltage power distribution lines are acquired and used as the basis for fault judgment. Compared with the limitation of traditional leakage current protection relying only on the information of a single line, this invention integrates multi-source data from the main meter and charging pile sub-meters, realizing a more comprehensive perception of the line's operating status and significantly improving the accuracy of fault judgment.

[0010] Secondly, the fault judgment logic of this invention does not rely on the traditional single feature threshold of "current over-limit". Instead, it uses fault detection start criteria, fault occurrence detection criteria and fault duration calculation to comprehensively utilize the current characteristics (such as abnormal current changes), voltage characteristics (such as abnormal voltage changes), and fault duration characteristics (such as the duration of fault conditions) during the fault to perform multi-feature fusion judgment. This avoids the limitations of traditional single feature threshold judgment and further improves the accuracy of fault identification.

[0011] Furthermore, for charging load access scenarios, this invention can effectively distinguish between high current and short-term high load caused by charging load and actual line faults by specifically acquiring charging pile sub-meter data and by designing "the duration of the fault condition being met and the pre-set fault judgment time threshold". This avoids misjudging high load and instantaneous disturbance of electric vehicle charging as line faults and ensures the accuracy of fault detection in charging load access scenarios.

[0012] In this invention, the real-time acquisition of three-phase voltage and current data collected from the main meter and charging pile sub-meters in low-voltage power distribution lines refers to the real-time electrical parameters collected by the main meter and charging pile sub-meters that reflect the power supply voltage level and electrical load intensity at their respective locations, used to monitor the operating status of the corresponding low-voltage power distribution lines. Specifically, the first time interval is 15 minutes, meaning data is collected every 15 minutes; the second time interval is 1 minute, meaning data is collected every 1 minute. Furthermore, the data collected from the main meter and charging pile sub-meters must cover phases A, B, and C to comprehensively reflect the three-phase electrical status of the line and avoid monitoring blind spots caused by missing single-phase data.

[0013] In this invention, the master meter is a total metering device that covers all electrical equipment in a certain area (such as a residential area or transformer area) and records the electrical parameters of that area, while the charging pile sub-meter is a branch metering device within the coverage area of ​​the master meter and records the electrical parameters of the corresponding charging pile separately.

[0014] Further, in step S1, the fault detection activation criterion includes at least one of the following: a low voltage criterion, an overcurrent criterion, and a current increase factor criterion; wherein, the low voltage criterion is constructed by setting a total meter voltage change setting value, and if the difference between the voltage value of at least one phase of the three phases of the total meter at the previous sampling time and the voltage value at the current sampling time is greater than or equal to the total meter voltage change setting value, then the fault detection activation condition is determined to be met; the overcurrent criterion is constructed by setting a total meter current setting value, and if the current of any phase of the three phases of the total meter at the current sampling time is greater than or equal to the total meter current setting value, then the fault detection activation condition is determined to be met; the current increase factor criterion is constructed by setting a current change factor setting value as a linear relationship coefficient, and if the current value of at least one phase of the three phases of the total meter at the current sampling time is greater than or equal to the product of the current value at the previous sampling time and the current change factor setting value, then the fault detection activation condition is determined to be met.

[0015] The formula for the low voltage criterion is as follows:

[0016]

[0017] In the formula: This represents the three phases A, B, and C; For the summary table The voltage value of the phase at the current sampling moment; For the summary table The voltage value of the phase at the previous sampling time; ΔU set This is the set value for the voltage change of the main meter.

[0018] The formula for the overcurrent criterion is as follows:

[0019]

[0020] In the formula: This represents the three phases A, B, and C; For the summary table The current value of the phase at the current sampling moment; I set This is the current setting value for the main meter.

[0021] The formula for the current increase factor criterion is as follows:

[0022]

[0023] In the formula: This represents the three phases A, B, and C; For the summary table The current value of the phase at the current sampling moment; For the summary table The current value of the phase at the previous sampling time; k is the current change factor setting value.

[0024] Furthermore, in step S3, if the low voltage criterion, overcurrent criterion, and current increase factor criterion are all satisfied simultaneously, then the fault detection start-up conditions are determined to be met.

[0025] Furthermore, in step S4, based on remote communication instructions, the sampling time interval is shortened so that the three-phase voltage data and three-phase current data collected at the main meter and charging pile sub-meters in the low-voltage distribution line can be obtained in real time based on the second time interval.

[0026] In this invention, the real-time acquisition of three-phase voltage and three-phase current data collected from the main meter and charging pile sub-meters in the low-voltage distribution line based on the second time interval is achieved through remote summoning. Specifically, with the help of remote communication commands (such as commands issued by the remote monitoring platform of the power system), a request to adjust the time interval is actively sent to each main meter and its charging pile sub-meters, requesting them to shorten the data sampling time interval from the first time interval in step S2 (e.g., once every 15 minutes) to the second time interval (e.g., once every 1 minute). After each main meter and charging pile sub-meter responds to the command and adjusts the sampling time interval, they then upload more intensive three-phase voltage and current data in real time according to the shortened second time interval, providing more refined electrical parameter support for subsequent fault detection.

[0027] Further, in step S1, the fault detection criterion is constructed as follows: The main meter voltage setting value and the charging pile sub-meter current setting value are set. Under the condition of sampling based on the second time interval, if the voltage data of at least one phase of the main meter at a corresponding previous sampling time is less than or equal to the main meter voltage setting value, and the corresponding current data at a corresponding previous sampling time is... If the current value of the corresponding phase in the three phases of the charging pile sub-meter under the main meter is greater than or equal to the current setting value of the main meter, and the current value of the corresponding phase in the three phases of the charging pile sub-meter at the current sampling time is less than or equal to the current setting value of the charging pile sub-meter, then the fault condition is determined to be met. Here, "at least one phase" means at least one of the three phases A, B, and C. Of course, in the preferred embodiment, it can be all three phases. The "corresponding phase" refers to the phase of the three phases that corresponds to the aforementioned at least one phase.

[0028] The formula for the fault detection criterion is as follows:

[0029]

[0030] In the formula: This represents the three phases A, B, and C; and For the summary table The voltage and current values ​​of the phase at the current sampling moment; Charging pile sub-meters under the master table The current value of the phase at the current sampling moment; U set This is the main meter voltage setting value; I set This is the current setting value for the main meter; I CPset This is the current setting value for the charging pile sub-meter.

[0031] Furthermore, in step S5, during the process of determining whether the fault conditions are met based on the fault occurrence detection criteria, the voltage and current data of each phase in the three phases of the main meter and the charging pile sub-meters under the main meter can be judged independently. This design not only fits the actual operating scenario in low-voltage power distribution lines where single-phase, two-phase, and three-phase faults may occur, but also comprehensively captures faults of different phases through independent three-phase judgment, effectively avoiding fault omissions caused by the correlation of three-phase judgments; at the same time, each phase can be independently matched with the corresponding charging pile sub-meter data to eliminate interference, further ensuring the accuracy of fault detection.

[0032] It should be noted that the "current sampling time" involved in the fault detection start-up criterion of this invention corresponds to the moment when the main meter collects the three-phase voltage and current data at the first time interval. This data is only used to determine whether the low-voltage distribution line corresponding to the main meter meets the start-up conditions. The "current sampling time" involved in the fault occurrence detection criterion corresponds to the moment when the main meter and the charging pile sub-meters collect the three-phase voltage and current data at the second time interval (less than the first time interval). This data is only used to determine whether the line meets the fault conditions. Furthermore, the activation of the second time interval requires the main meter and the charging pile sub-meters to switch the sampling time interval after the start-up conditions are met, triggered by a remote summoning command. In terms of time relationship, the "current sampling time" involved in the fault occurrence detection criterion lags behind the "current sampling time" involved in the fault detection start-up criterion by a second time interval, in order to intensively capture the changes in electrical parameters after the start-up conditions are triggered, providing data support for fault judgment.

[0033] Further, in step S6, the duration of meeting the fault conditions is calculated. If the duration reaches a preset fault judgment time threshold, the steps for determining that a fault has occurred in the low-voltage distribution line include: S601, starting the timer from the moment the fault conditions are first determined to be met; S602, during the timer, based on step S4, continuously acquiring the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter based on the second time interval, and executing step S5 to determine whether the fault conditions are met based on the fault occurrence detection criterion; S603, if the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter acquired by N consecutive samplings all meet the fault conditions after being judged by the fault occurrence detection criterion, the timer continues to accumulate; if any sampled data does not meet the fault conditions after being judged by the fault occurrence detection criterion, the timer is reset to zero and the timer stops, and the timer is restarted when sampled data that meets the fault conditions is detected again; S604, if the time of continuous accumulation reaches the preset fault judgment time threshold, the low-voltage distribution line is determined to have a fault. Where N≥1, this invention solves the problems of user charging interruption, frequent start-stop of protection devices and equipment wear caused by traditional fault detection methods that do not consider the duration of abnormality and mistakenly regard charging load disturbances as faults. At the same time, by using continuous judgment of dense sampling data, the accuracy of fault duration calculation is improved, providing reliable support for accurate determination of line faults. Ultimately, it not only ensures the operational stability of low-voltage power distribution lines, but also ensures the reliability of power supply after the charging load is connected.

[0034] In this invention, when a fault is detected in a low-voltage power distribution line, relevant maintenance personnel are notified to conduct inspections. Notification methods include SMS, telephone, and push notifications from the power operation and maintenance management system. The notification content includes the specific number of the faulty meter, the time of the fault, the relevant power grid line and transformer information, the faulty phase, and any abnormal electrical parameters. This allows relevant personnel to carry the necessary tools, accurately locate the fault point, and carry out inspection and handling work.

[0035] The second aspect of this invention discloses a system for implementing the fault detection method for low-voltage distribution lines suitable for charging load access disclosed in the first aspect of this invention, comprising: a criterion construction unit, configured to pre-construct a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred, wherein the fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line, and the fault occurrence detection criterion is constructed based on the three-phase voltage and current data of the main meter and the charging pile sub-meters in the low-voltage distribution line; a first data acquisition unit, configured to acquire the three-phase voltage data and three-phase current data collected at the main meter and the charging pile sub-meters in the low-voltage distribution line in real time based on a first time interval; and a fault detection initiation judgment unit, configured to substitute the acquired three-phase voltage data and three-phase current data of the main meter into the fault... The system includes a fault detection initiation criterion to determine whether the fault detection initiation conditions are met; a second data acquisition unit, configured to acquire three-phase voltage and three-phase current data collected from the main meter and charging pile sub-meters in the low-voltage distribution line in real time based on a second time interval, wherein the second time interval is shorter than the first time interval; a fault occurrence detection unit, configured to substitute the three-phase voltage and three-phase current data from the main meter and charging pile sub-meters acquired in real time by the second data acquisition unit into the fault occurrence detection criterion to determine whether the fault conditions are met; if the fault occurrence detection unit determines that the fault conditions are met, the system continues to repeatedly detect whether the fault conditions are met; and a fault occurrence determination unit, configured to calculate the duration of the fault conditions being met, and if the duration reaches a preset fault determination time threshold, then the low-voltage distribution line is determined to have a fault.

[0036] The third aspect of the present invention discloses an electronic device, which includes a memory and a processor. The memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to perform the low-voltage power distribution line fault detection method for charging load access disclosed in the first aspect of the present invention.

[0037] The fourth aspect of the present invention discloses a readable storage medium storing computer program instructions, which, when read and executed by a processor, perform the fault detection method for low-voltage power distribution lines suitable for charging load access disclosed in the first aspect of the present invention.

[0038] The beneficial effects of this invention are as follows:

[0039] (1) This invention obtains voltage and current data of power distribution lines through electricity meters, and uses this data as a basis to judge whether the line may be in a fault state. Compared with traditional leakage current protection which only applies to the information of this line, this invention comprehensively uses the information of the main meter and the sub-meters of each charging pile, and the multi-source information fusion makes the fault judgment more accurate.

[0040] (2) The fault detection start criterion and fault occurrence detection criterion of the present invention not only use the single feature threshold of "current over-limit", but also comprehensively utilize the characteristics of current surge, voltage drop and fault persistence during fault, and the multi-feature fusion judgment of fault is more accurate.

[0041] (3) The present invention also takes into account the effects of electric vehicle charging load and short-term impact load, avoiding the risk of electric vehicle charging load and instantaneous disturbance being misjudged as line faults, and improving the accuracy of power distribution line fault detection.

[0042] The present invention discloses in detail, with reference to the embodiments shown in the accompanying drawings and the reference numerals, a method and system for detecting faults in low-voltage power distribution lines with charging load access. Attached Figure Description

[0043] Figure 1 This is a flowchart of the steps of the fault detection method for low-voltage power distribution lines applicable to charging load access according to the present invention;

[0044] Figure 2 This is a line graph of the voltage and current data recorded by the meter in Embodiment 1 of the present invention;

[0045] Figure 3 This is a line graph of the voltage and current data recorded by the meter in Embodiment 2 of the present invention;

[0046] Figure 4 This is a line graph of the voltage and current data recorded by the meter in Embodiment 3 of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0048] like Figure 1 As shown, this invention discloses a fault detection method for low-voltage distribution lines suitable for charging load access, comprising the following steps: S1, pre-constructing a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred, wherein the fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line, and the fault occurrence detection criterion is constructed based on the three-phase voltage and current data of the main meter and the charging pile sub-meters in the low-voltage distribution line; S2, acquiring the three-phase voltage data and three-phase current data collected at the main meter and the charging pile sub-meters in the low-voltage distribution line in real time based on a first time interval; S3, combining the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meters acquired in step S2. S4. Substitute the streaming data into the fault detection start criterion to determine whether the fault detection start condition is met; S5. If the fault detection start condition is met as determined in step S3, then start acquiring the three-phase voltage data and three-phase current data collected from the main meter and charging pile sub-meters in the low-voltage distribution line in real time based on the second time interval; wherein, the second time interval is less than the first time interval; S6. Substitute the three-phase voltage data and three-phase current data of the main meter and charging pile sub-meters acquired in real time in step S4 into the fault occurrence detection criterion to determine whether the fault condition is met; S7. If the fault condition is met, then continue to repeat step S4, and calculate the duration of meeting the fault condition. If the duration reaches the preset fault judgment time threshold, then determine that a fault has occurred in the low-voltage distribution line.

[0049] Based on the above-disclosed steps, this invention acquires three-phase voltage and three-phase current data collected in real time from the main meter and sub-meters of the charging pile in the low-voltage distribution line. It fully combines the unique dynamic electrical characteristics of the charging load (such as the short-term inrush current when the three-phase fast charging equipment starts up, and the short-term superposition of large loads in the centralized charging scenario). This effectively solves the problem that the traditional method only uses "current over-limit" as the single standard for judging line faults and does not consider the dynamic characteristics of the charging load, which makes it easy to misjudge the normal start-up and operation of the three-phase fast charging equipment as a line fault.

[0050] Secondly, the data acquisition strategy is based on a first time interval and a second time interval shorter than the first time interval. This avoids unnecessary resource waste caused by high-frequency sampling and ensures the accuracy and timeliness of data acquisition under abnormal conditions. It provides detailed and reliable data support for the calculation of subsequent fault detection criteria and the accurate extraction of fault characteristics, further helping to distinguish between normal fluctuations in charging load and actual line faults.

[0051] Furthermore, the fault detection initiation criterion of this invention uses only the main meter data in the low-voltage power distribution line, which reduces the amount of data and computational complexity in the initial judgment stage, and can quickly screen out suspicious lines, thus improving processing efficiency. The fault detection criterion combines the main meter data and the charging pile sub-meter data, and can accurately distinguish between normal fluctuations in charging load and real line faults through the collaborative judgment of the two, thus eliminating the problem of misjudgment in traditional methods.

[0052] Meanwhile, this invention does not rely solely on the traditional single feature threshold of "current over-limit". Instead, it comprehensively utilizes multiple features such as current surge, voltage drop, and fault duration during a fault by using fault detection initiation criteria, fault occurrence detection criteria, and fault duration calculation. Through the fusion of multiple features, a more rigorous judgment logic is formed, further improving the accuracy of fault detection.

[0053] Furthermore, when the data of the low-voltage distribution line's main meter reaches the fault detection activation criterion, the protection is not triggered instantly. Instead, it repeatedly verifies the fault occurrence detection criterion, accumulates the duration of the fault condition being met, and uses a pre-set threshold as the basis for fault judgment. This design can accurately distinguish between short-term current rises caused by short-term heavy loads and sudden current surges caused by faults, thereby reducing the impact of frequent power outages at charging stations on user travel and station operations. At the same time, it avoids the problem of repeated operation of protection devices generating operational overvoltages that accelerate line aging, increase the maintenance pressure on power supply companies, and create safety hazards.

[0054] In this invention, the real-time acquisition of three-phase voltage data and three-phase current data collected from the main meter and charging pile sub-meters in low-voltage power distribution lines refers to the real-time electrical parameters collected by the main meter and charging pile sub-meters that reflect the power supply voltage level and power load intensity at their respective locations, and are used to monitor the operating status of the corresponding low-voltage power distribution lines.

[0055] Specifically, the first time interval is typically 15 minutes, and the second time interval is typically 1 minute. Furthermore, the data collected from the master meter and the charging pile sub-meters includes three-phase data (A, B, and C), thus comprehensively reflecting the three-phase electrical status of the line and avoiding monitoring blind spots caused by missing data from only single phases.

[0056] In this embodiment of the invention, the master meter is a total metering device covering all electrical equipment in a certain area (such as a residential area or transformer area), which records the electrical parameters of that area, while the charging pile sub-meter is a branch metering device within the coverage area of ​​the master meter, which records the electrical parameters of the corresponding charging pile separately.

[0057] In one specific embodiment, the voltage and current data of the main meter and charging pile sub-meters in a certain area are sampled every 15 minutes within a 24-hour period, as shown in Table 1. A line graph is plotted based on the data as follows. Figure 2 As shown.

[0058] Table 1 Voltage and current data for Example 1 (Unit: V, A)

[0059]

[0060]

[0061]

[0062] In a preferred embodiment of the present invention, in step S1, the fault detection activation criterion includes at least one of the following: a low voltage criterion, an overcurrent criterion, and a current increase factor criterion; wherein, the low voltage criterion is constructed by setting a total meter voltage change setting value, and if the difference between the voltage value of at least one phase of the three phases of the total meter at the previous sampling time and the voltage value at the current sampling time is greater than or equal to the total meter voltage change setting value, then it is determined that the fault detection activation condition is met; the overcurrent criterion is constructed by setting a total meter current setting value, and if the current of any phase of the three phases of the total meter at the current sampling time is greater than or equal to the total meter current setting value, then it is determined that the fault detection activation condition is met; the current increase factor criterion is constructed by setting a current change factor setting value as a linear relationship coefficient, and if the current value of at least one phase of the three phases of the total meter at the current sampling time is greater than or equal to the product of the current value at the previous sampling time and the current change factor setting value, then it is determined that the fault detection activation condition is met. In this embodiment, the present invention breaks through the limitation of traditional fault detection relying solely on the single starting condition of "overcurrent". It provides three types of judgment criteria—low voltage criterion, overcurrent criterion, and current increase factor criterion—to address different electrical characteristics of faults such as sudden voltage drop, current over-limit, and current change. These criteria can capture precursor signals at different stages of the fault, avoiding the risk of missing faults due to a single criterion. Simultaneously, it allows for the flexible selection of "one or several combinations" of criteria, adapting to different power distribution scenarios. Furthermore, based on the judgment of three-phase data from the main meter, it can cover various fault triggering conditions of three-phase lines, reducing the problem of missed single-phase faults and improving the scenario adaptability and comprehensiveness of the fault detection initiation stage.

[0063] The formula for the low voltage criterion is as follows:

[0064]

[0065] In the formula: This represents the three phases A, B, and C; For the summary table The voltage value of the phase at the current sampling moment; For the summary table The voltage value of the phase at the previous sampling time; ΔU set This is the set value for the voltage change of the main meter.

[0066] The formula for the overcurrent criterion is as follows:

[0067]

[0068] In the formula: This represents the three phases A, B, and C; For the summary table The current value of the phase at the current sampling moment; I set This is the current setting value for the main meter.

[0069] The formula for the current increase factor criterion is as follows:

[0070]

[0071] In the formula: This represents the three phases A, B, and C; For the summary table The current value of the phase at the current sampling moment; For the summary table The current value of the phase at the previous sampling time; k is the current change factor setting value.

[0072] In a preferred embodiment of the present invention, in step S3, if the low voltage criterion, the overcurrent criterion, and the current increase factor criterion are all satisfied simultaneously, then it is determined that the fault detection start-up condition is met. Furthermore, in this embodiment, ΔU set Take 10V, I set Choose 65A, and k = 4.

[0073] In this embodiment of the invention, in step S3, determining whether the fault detection start-up condition is met means that at least one of the voltage and current data of phases A, B, and C meets the fault detection start-up criterion. In a specific embodiment, it can be at least one of phases A, B, and C. In a more preferred embodiment, it can be all three phases A, B, and C.

[0074] Calculations show that, in this embodiment, Figure 2 The starting time of the shaded area shown meets the startup conditions.

[0075] In a preferred embodiment of the present invention, in step S4, the sampling time interval is shortened based on a remote communication command, so that the three-phase voltage data and three-phase current data collected at the main meter and charging pile sub-meters in the low-voltage distribution line can be acquired in real time based on the second time interval. In this embodiment, the sampling interval between the main meter and the charging pile sub-meters can be quickly triggered by the remote communication command, without manual operation, which is suitable for the scenario of dispersed meters in low-voltage distribution lines and significantly improves the fault response speed; at the same time, it can acquire more dense voltage and current data in a timely manner, providing high-frequency and fine electrical parameter support for subsequent fault detection criteria, avoiding the loss of key data in the early stage of the fault due to excessively long sampling intervals, and further ensuring the accuracy and timeliness of fault judgment.

[0076] In one specific embodiment, with the help of instructions issued by the remote monitoring platform of the power system, a request to adjust the time interval is actively sent to each main meter and its charging pile sub-meters, requesting them to shorten the data sampling time interval from the first time interval (e.g., once every 15 minutes) in step S2 to the second time interval (e.g., once every 1 minute). After each main meter and charging pile sub-meter responds to the instruction and adjusts the sampling time interval, they then upload more intensive three-phase voltage and current data in real time according to the shortened second time interval, providing more refined electrical parameter support for subsequent fault detection.

[0077] In a preferred embodiment of the present invention, in step S1, the fault detection criterion is constructed as follows: A main meter voltage setting value and a charging pile sub-meter current setting value are set. Under the condition of sampling based on a second time interval, if the voltage data of at least one of the three phases of the main meter at the previous sampling time is less than or equal to the main meter voltage setting value, and the current data of the phase corresponding to the aforementioned at least one phase at the current sampling time is... If the current value of the corresponding phase in the three phases of the charging pile sub-meter under the main meter is greater than or equal to the current setting value of the charging pile sub-meter at the current sampling time, then the fault condition is determined to be met.

[0078] The formula for the fault detection criterion is as follows:

[0079]

[0080] In the formula: This represents the three phases A, B, and C; and For the summary table The voltage and current values ​​of the phase at the current sampling moment; Charging pile sub-meters under the master table The current value of the phase at the current sampling moment; U set This is the main meter voltage setting value; I set This is the current setting value for the main meter; I CPsetThis is the current setting value for the charging pile sub-meter.

[0081] In an embodiment of the present invention, U set Take 220V, I set Take 65A, I CPset Take 25.

[0082] It should be noted that the "current sampling time" involved in the fault detection start-up criteria (low voltage criterion, overcurrent criterion, and current increase multiple criterion) of this invention refers to the moment when the main meter collects the three-phase voltage and current data at a first time interval, which is conventionally set to 15 minutes. The data collected at this moment is only used to substitute into the fault detection start-up criteria to determine whether the low-voltage distribution line corresponding to the main meter meets the start-up conditions, and this "current sampling time" is completely synchronized with the time node of the main meter data collection, specifically it can be represented by fixed moments of the first time interval such as t0, t0+15min, t0+30min, etc.

[0083] The "current sampling time" involved in the fault detection criterion refers to the moment when the main meter and charging pile sub-meters collect three-phase voltage and current data at the second time interval, and the second time interval is shorter than the first time interval, typically taken as 1 minute. The data collected at this moment is only used to substitute into the fault detection criterion to determine whether the line meets the fault conditions, and this "current sampling time" must be achieved through remote activation. That is, only when the activation conditions are met will the system, through remote communication commands, request the main meter and charging pile sub-meters to switch the sampling time interval from the first time interval to the second time interval. The moment when data is subsequently collected at the second time interval is the "current sampling time" of the fault detection criterion.

[0084] In terms of time sequence, the "current sampling time" of the fault occurrence detection criterion lags behind the "current sampling time" of the fault detection initiation criterion, and the lag time is strictly one second time interval. Specifically, if the first time interval is 15 minutes, the "current sampling time" of the fault detection initiation criterion is t0+15 minutes, that is, the moment when the main meter in step S2 collects data at t0+15 minutes. If the initiation condition is met by step S3, the system will immediately trigger step S4, which switches the sampling time interval of the main meter and the charging pile sub-meters to 1 minute (i.e., the second time interval) through a remote summoning command. Then, the first "current sampling time" of the fault occurrence detection criterion is t0+15 minutes + 1 minute = t0+16 minutes, which is one second time interval later than the "current sampling time" of the fault detection initiation criterion. The "current sampling time" of subsequent steps S4 will be t0+17 minutes, t0+18 minutes, etc., all continuing according to the second time interval, so as to densely capture the changes in electrical parameters after the initiation condition is triggered, providing accurate data support for fault judgment.

[0085] In this invention, in step S5, determining whether the fault condition is met means when... If the phase voltage and current data meet the fault detection criteria, then it is determined that a fault has occurred in the low-voltage distribution line under that main meter. Phase fault. It should be noted that the fault conditions are determined independently for phases A, B, and C. That is, the fault conditions of phases A, B, and C are not mutually exclusive, and all three can exist simultaneously.

[0086] Specifically, in the process of determining whether fault conditions are met based on fault occurrence detection criteria, the voltage and current data of each phase in the three phases of the main meter and the charging pile sub-meters under the main meter can be judged independently. This design not only fits the actual operating scenario in low-voltage power distribution lines where single-phase, two-phase, and three-phase faults can all occur, but also comprehensively captures faults of different phases through independent three-phase judgment, effectively avoiding missed faults caused by the correlation of three-phase judgments; at the same time, each phase can be independently matched with the corresponding charging pile sub-meter data to eliminate interference, further ensuring the accuracy of fault detection.

[0087] In the existing low-voltage power distribution line fault detection technology system, those skilled in the art are prone to fall into the technical trap of "single-line independent protection". Specifically, in traditional power distribution networks, protection devices such as air switches and leakage current protection are installed independently on their respective lines, and faults are judged only by single signals such as current and leakage current of the line. This "single-line, single-parameter" protection mode has long been the industry consensus. Those skilled in the art generally assume that fault detection only needs to rely on the local electrical information of a single line, without the need for cross-line and cross-equipment collaborative data.

[0088] The proposed method in this application is to upload the current data of each line measured by each main meter and charging pile sub-meter to the network, and then perform distribution network fault detection based on the multi-source data from each main meter and charging pile sub-meter. This breaks the traditional thinking of distribution network protection methods, that is, it overcomes the limitations of the technical formula of single-line independent protection and realizes the fusion of multi-line and multi-device multi-source data.

[0089] Meanwhile, in traditional scenarios, the master meter is typically defined as a regional overall electricity metering tool, used to statistically analyze the total voltage and current of a specific area (such as a residential community or transformer substation). Charging pile sub-meters, on the other hand, serve as branch metering devices, recording the electricity consumption parameters of individual charging piles. The functional boundaries between the two are strictly separated, and technicians often believe that both types of meters are only used for measurement, failing to recognize the synergistic value of combining their electrical parameters with the dynamic characteristics of the charging load (such as short-term inrush currents and concentrated charging load superposition) to form a fault diagnosis system. This leads to a fixed bias in technicians' understanding of the functions of the master meter and charging pile sub-meters, making it difficult for conventional thinking to apply the proposed solution in this application—"integrating multi-source information from the master meter and charging pile sub-meters for fault detection." More importantly, to achieve effective integration of information from the main meter and the charging pile sub-meters, it is necessary to overcome core challenges not addressed by traditional technologies: First, the time synchronization of the two types of meter data needs to be resolved (such as the switching and adaptation between the first and second time intervals in this invention, ensuring accurate time matching between the main meter's voltage drop and current over-limit data and the charging pile sub-meter's normal current fluctuation data); second, a composite criterion based on multi-source data needs to be constructed (breaking through the traditional single standard of "current over-limit," simultaneously linking the main meter's voltage change and current change multiple with the charging pile sub-meter's current threshold to distinguish between charging disturbances and actual faults). Traditional technologies lack both practical experience in such multi-source data collaborative analysis and a criterion design approach tailored to charging load characteristics. This application creatively designs a fault criterion that integrates main meter data and charging pile sub-meter data from multiple sources, thereby solving the aforementioned technical problems.

[0090] In a preferred embodiment of the present invention, in step S6, the duration of meeting the fault conditions is calculated. If the duration reaches a preset fault judgment time threshold, the step of judging that a fault has occurred in the low-voltage distribution line includes: S601, starting the timer from the moment the fault conditions are first judged to be met; S602, during the timer, based on step S4, continuously acquiring the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter based on the second time interval, and executing step S5 to judge whether the fault conditions are met based on the fault occurrence detection criterion; S603, if the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter acquired by N consecutive samplings all meet the fault conditions after being judged by the fault occurrence detection criterion, the timer continues to accumulate; if any sampled data does not meet the fault conditions after being judged by the fault occurrence detection criterion, the timer is reset to zero and the timer stops, and the timer is restarted when sampled data that meets the fault conditions is detected again; S604, if the time of continuous accumulation of the timer reaches the preset fault judgment time threshold, the low-voltage distribution line is judged to have a fault. In this embodiment, N≥1, and the preset fault judgment time threshold is 30 minutes. In this embodiment, the present invention solves the problems of user charging interruptions, frequent start-stop of protection devices, and equipment wear caused by traditional fault detection methods that fail to consider the duration of abnormalities and mistakenly treat charging load disturbances as faults. Simultaneously, by continuously judging through dense sampling data, the accuracy of fault duration calculation is improved, providing reliable support for accurately determining line faults. Ultimately, this ensures both the operational stability of low-voltage distribution lines and the reliability of power supply after charging load access.

[0091] like Figure 2 As shown, in this embodiment, the gray shaded area represents the duration of the fault detection criterion, which is 60 minutes. Since the duration of the gray shaded area reaches the preset 30-minute threshold, the judgment result is: a fault has occurred in the power distribution line within the gray shaded area. Subsequent inspection by the power distribution network maintenance personnel confirmed that the fault was caused by wind blowing, resulting in a short circuit between the bamboo and the twisted wire of the line, and the change in electrical quantity corresponding to the shaded area was consistent with the judgment result of the fault detection activation criterion in step S3.

[0092] In this embodiment of the invention, when a fault is detected in a low-voltage power distribution line, relevant maintenance personnel are notified to conduct inspections. Notification methods include SMS, telephone, and push notifications from the power operation and maintenance management system. The notification content includes the specific number of the faulty meter, the time of the fault, the relevant power grid line and transformer information, the faulty phase, and abnormal electrical parameters. This allows relevant personnel to carry the necessary tools, accurately locate the fault point, and carry out inspection and handling work.

[0093] In one specific embodiment, the edited text message is as follows:

[0094] [XX Power] [Low-voltage Line Fault Alert] XX Power Supply Business Office: [Meter Number: XXXX] At XX:XX on XX month XX year, a fault is suspected to have occurred on phase XX of the power grid line XX (current XXA, a surge of XX times; voltage XXV, a drop of XXV compared to the previous moment). Relevant personnel are requested to pay attention and conduct inspections!

[0095] After subsequent line inspections, the power distribution maintenance personnel discovered that the short circuit in the stranded wire was caused by wind blowing bamboo, which was consistent with the test results.

[0096] In another specific embodiment, the voltage and current data of the main meter and the charging pile sub-meters are sampled every 15 minutes within a 24-hour period, as shown in Table 2. A line graph is plotted based on the data as follows. Figure 3 As shown.

[0097] Table 2 Voltage and current data for Example 2 (Unit: V, A)

[0098]

[0099]

[0100]

[0101] from Figure 3 As can be seen from this embodiment, the charging pile current does not meet the fault detection criterion of less than 25A, the fault duration timer terminates, and the preset threshold is not reached, so it is determined that no fault has occurred in the line. After subsequent on-site inspection, it was found that the current surge was caused by the user charging the electric vehicle under the meter, not by a fault in the power distribution line. The change in electrical quantity in the shaded area is consistent with the judgment result of the fault detection start criterion in step S3.

[0102] In another specific embodiment, the voltage and current data of the main meter and the charging pile sub-meters are sampled every 15 minutes within a 24-hour period, as shown in Table 3. A line graph is plotted based on the data as follows. Figure 4 As shown.

[0103] Table 3 Voltage and current data for Example 3 (Units: V, A)

[0104]

[0105]

[0106]

[0107] from Figure 4As can be seen from this embodiment, the gray shaded area represents the duration of the fault detection criterion, which is 15 minutes. Since the duration of the gray shaded area did not reach the preset 30-minute threshold, the judgment result is: no fault occurred in the power distribution line within the gray shaded area. After subsequent on-site inspection and confirmation, the surge in current of the main meter was caused by a short-term high load. At the same time, the "current surge and voltage drop" characteristics exhibited by the shaded area meet the "overcurrent criterion" and "undervoltage criterion" respectively, satisfying the fault detection start condition of step S3. Therefore, the change in electrical quantity in the shaded area is completely consistent with the judgment result of step S3.

[0108] This invention also discloses a system for implementing the fault detection method for low-voltage distribution lines suitable for charging load access disclosed in this invention, comprising: a criterion construction unit, configured to pre-construct a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred, wherein the fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line, and the fault occurrence detection criterion is constructed based on the three-phase voltage and current data of both the main meter and the charging pile sub-meters in the low-voltage distribution line; a first data acquisition unit, configured to acquire the three-phase voltage data and three-phase current data collected at the main meter and the charging pile sub-meters in the low-voltage distribution line in real time based on a first time interval; and a fault detection initiation judgment unit, configured to substitute the acquired three-phase voltage data and three-phase current data of the main meter into the fault detection initiation... The system comprises the following components: a first data acquisition unit and a second data acquisition unit. The first data acquisition unit is configured to acquire, in real time, three-phase voltage and three-phase current data collected from the main meter and charging pile sub-meters in the low-voltage distribution line based on a second time interval, provided that the fault detection start conditions are met. The second time interval is shorter than the first time interval. The second data acquisition unit is configured to substitute the three-phase voltage and three-phase current data acquired in real time by the second data acquisition unit into the fault occurrence detection criteria to determine whether the fault conditions are met. If the fault occurrence detection unit determines that the fault conditions are met, it continues to repeatedly detect whether the fault conditions are met. The third data acquisition unit is configured to calculate the duration of the fault conditions being met. If the duration reaches a preset fault judgment time threshold, it determines that a fault has occurred in the low-voltage distribution line. It should be noted that the first data acquisition unit and the second data acquisition unit can be implemented in the same unit, or they can be set as two independent units or have independent functions but are integrated into one unit.

[0109] The present invention also discloses an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor runs the computer program to enable the electronic device to perform the fault detection method for low-voltage power distribution lines suitable for charging load access disclosed in the present invention.

[0110] The present invention also discloses a readable storage medium storing computer program instructions, which are read and executed by a processor to perform the fault detection method for low-voltage power distribution lines suitable for charging load access disclosed in the present invention.

[0111] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., may be used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0112] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and combinations thereof.

[0113] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fault detection method for low-voltage distribution lines suitable for charging load access, characterized in that, Includes the following steps: S1, a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred are pre-constructed. The fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line. The fault occurrence detection criterion is constructed based on the three-phase voltage and current data of the main meter and the charging pile sub-meter in the low-voltage distribution line. S2, based on the first time interval, acquire in real time the three-phase voltage data and three-phase current data collected at the main meter and the sub-meter of the charging pile in the low-voltage power distribution line; S3, Substitute the three-phase voltage data and three-phase current data of the total meter obtained in step S2 into the fault detection start criterion to determine whether the fault detection start condition is met. S4. If the fault detection start condition is met in step S3, then the three-phase voltage data and three-phase current data collected from the main meter and the charging pile sub-meter in the low-voltage distribution line are acquired in real time based on the second time interval; wherein, the second time interval is shorter than the first time interval. S5, substitute the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter obtained in real time in step S4 into the fault occurrence detection criteria to determine whether the fault conditions are met. S6. If the fault condition is met, continue to repeat step S4 and calculate the duration of the fault condition. If the duration reaches the preset fault judgment time threshold, the low-voltage power distribution line is judged to have a fault.

2. The method according to claim 1, characterized in that, In step S1, the fault detection activation criterion includes at least one of the following: low voltage criterion, overcurrent criterion, and current increase factor criterion; The low voltage criterion is constructed as follows: a set value for the voltage change of the main meter is set. If the difference between the voltage value of at least one phase of the main meter at the previous sampling time and the voltage value at the current sampling time is greater than or equal to the set value for the voltage change of the main meter, then the fault detection start condition is met. The overcurrent criterion is constructed as follows: set the current setting value of the main meter. If the current of any one of the three phases of the main meter is greater than or equal to the current setting value of the main meter at the current sampling time, it is determined that the fault detection start condition is met. The current increase factor criterion is constructed as follows: the current change factor setting value is set as a linear relationship coefficient. If the current value of at least one phase of the three phases of the main meter at the current sampling time is greater than or equal to the product of the current value at the previous sampling time and the current change factor setting value, then the fault detection start condition is met.

3. The method according to claim 1, characterized in that, In step S3, if the low voltage criterion, overcurrent criterion, and current increase factor criterion are all satisfied simultaneously, then the fault detection start-up conditions are determined to be met.

4. The method according to claim 2 or 3, characterized in that, In step S4, based on remote communication instructions, the sampling time interval is shortened so that the three-phase voltage data and three-phase current data collected at the main meter and charging pile sub-meters in the low-voltage distribution line can be obtained in real time based on the second time interval.

5. The method according to claim 2 or 3, characterized in that, In step S1, the fault detection criterion is constructed as follows: a main meter voltage setting value and a charging pile sub-meter current setting value are set. Under the condition of sampling based on the second time interval, if the voltage data of at least one phase of the main meter at the previous sampling time is less than or equal to the main meter voltage setting value, and the current data of the corresponding phase at the current sampling time is greater than or equal to the main meter current setting value, and the current value of the corresponding phase of the charging pile sub-meter at the current sampling time is less than or equal to the charging pile sub-meter current setting value, then the fault condition is determined to be met.

6. The method according to claim 5, characterized in that, In step S5, during the process of determining whether the fault conditions are met based on the fault occurrence detection criteria, the voltage and current data of each phase in the three phases of the main meter and the charging pile sub-meters under the main meter can be judged independently.

7. The method according to claim 5, characterized in that, In step S6, the duration for which the fault conditions are met is calculated. If the duration reaches a preset fault judgment time threshold, the steps for determining that a fault has occurred in the low-voltage distribution line include: S601, the timer starts from the moment the fault condition is first determined to be met; S602, during the timing process, based on step S4, continuously acquire the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter based on the second time interval, and execute step S5 to determine whether the fault conditions are met based on the fault occurrence detection criteria. S603: If the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter obtained by N consecutive samplings all meet the fault conditions after being judged by the fault occurrence detection criteria, the timer will continue to accumulate; if any sampling data does not meet the fault conditions after being judged by the fault occurrence detection criteria, the timer will be cleared and stopped, and the timer will be restarted when sampling data that meets the fault conditions is detected again. S604 If the cumulative timing reaches the preset fault judgment time threshold, then a fault is judged to have occurred in the low-voltage power distribution line.

8. A system for implementing the fault detection method for low-voltage distribution lines suitable for charging load access according to any one of claims 1-7, characterized in that, include: The criterion construction unit is constructed by pre-constructing a fault detection initiation criterion for determining whether fault detection should be initiated and a fault occurrence detection criterion for determining whether a fault has occurred. The fault detection initiation criterion is constructed based on the three-phase voltage data and three-phase current data of the main meter in the low-voltage distribution line, and the fault occurrence detection criterion is constructed based on the three-phase voltage and current data of the main meter and the charging pile sub-meter in the low-voltage distribution line. The first data acquisition unit is configured to acquire, in real time, three-phase voltage data and three-phase current data collected from the main meter and the sub-meter of the charging pile in the low-voltage power distribution line based on a first time interval. The fault detection start-up judgment unit is constructed by substituting the three-phase voltage data and three-phase current data of the acquired main meter into the fault detection start-up criterion to determine whether the fault detection start-up conditions are met. The second data acquisition unit is configured such that, if the fault detection start condition is met, it begins to acquire three-phase voltage data and three-phase current data collected from the main meter and the sub-meter of the charging pile in the low-voltage distribution line in real time based on the second time interval; wherein, the second time interval is shorter than the first time interval. The fault detection unit is constructed by substituting the three-phase voltage data and three-phase current data of the main meter and the charging pile sub-meter, which are obtained in real time by the second data acquisition unit, into the fault detection criteria to determine whether the fault conditions are met. If the fault detection unit determines that the fault conditions are met, the fault detection unit continues to repeatedly detect whether the fault conditions are met. The fault occurrence determination unit is constructed by calculating the duration for which the fault conditions are met. If the duration reaches a preset fault judgment time threshold, then the low-voltage power distribution line is judged to have a fault.

9. An electronic device, characterized in that, The electronic device includes a memory and a processor, the memory storing a computer program, and the processor running the computer program to cause the electronic device to perform the low-voltage power distribution line fault detection method applicable to charging load access as described in any one of claims 1-7.

10. A readable storage medium, characterized in that, The readable storage medium stores computer program instructions, which, when read and executed by a processor, perform the low-voltage power distribution line fault detection method applicable to charging load access as described in any one of claims 1-7.

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