Positioning detection device and detection method for arc discharge electric leakage of multi-stage series system

Abstract

According to the positioning detection device and method for arc discharge electric leakage of the multi-stage series system, the multiple current detection nodes are arranged in the loop, analysis and logic judgment are conducted on the current difference values of the nodes, general electric leakage detection of an alternating current / direct current system is achieved, limitation of a traditional detection method on the direct current system is broken through, and the detection efficiency is improved. Accurate identification of the fault section in the multi-stage series system is realized, and the troubleshooting and repairing efficiency is improved. The device comprises a current loop, current acquisition devices are arranged at the head end and the tail end of the current loop, the current value obtained by the current acquisition device at the head end is compared with the current value obtained by the current acquisition device at the tail end, and if the difference value between the two current values exceeds a preset threshold value, it is judged that an arc discharge or electric leakage fault occurs in the current loop. And the current acquisition device is arranged between the head and the tail of the current loop, so that an arc discharge or electric leakage fault section of the current loop can be judged. The method is applied to the technical field of electrical safety detection.

Description

Technical Field

[0001] The present invention is applied to the technical field of electrical safety detection, and particularly relates to a positioning detection device and method for arc leakage in a multi-stage series system. Background Art

[0002] In AC / DC high and low voltage power distribution systems, such as series-connected photovoltaic modules, energy storage batteries, series-connected capacitors, and resistors, electrical fires caused by leakage and arcing due to cable / equipment aging occur frequently. Currently, there is a lack of timely and effective detection solutions, making it difficult to avoid accidents.

[0003] In the field of electrical safety detection, there are many deficiencies in the existing technologies: 1. Traditional leakage detection usually uses a single residual current transformer (RCD). This method can only detect whether there is a leakage situation in the total circuit and cannot locate the specific section where the fault occurs, making it difficult to quickly troubleshoot and repair the fault; 2. Since the DC system does not have the zero-crossing characteristic, traditional leakage detection methods designed based on AC characteristics completely fail in the DC system, unable to guarantee the electrical safety of the DC system. Currently, high-frequency arc analysis methods are used, with a high false alarm rate and inability to accurately locate; 3. For multi-stage series circuits, such as battery packs, once a local fault occurs, traditional detection means are difficult to achieve accurate fault location, affecting the normal operation and maintenance efficiency of the system; 4. The node positions of existing detection devices are fixed and cannot flexibly and dynamically expand detection points according to the actual complexity of the system, restricting their application in systems of different scales and structures; 5. In long-distance series lines, such as photovoltaic power generation systems, existing detection technologies cannot achieve sectional isolation of faults, and the faults may affect the normal operation of the entire line and even cause safety accidents.

[0004] For example, Chinese Patent No. CN104833893B discloses a leakage detection system and method, and Chinese Patent No. CN208537658U discloses a leakage detection terminal with intelligent alarm. For example, Chinese Patent No. CN115631594A discloses a system and method for arc detection and alarm of a busbar trunking. The former two are both designed for leakage detection in low-voltage areas, and the latter is an arc detection system for photovoltaic power generation. However, they do not report different levels of leakage differently. When multiple devices are tested simultaneously, multiple devices will alarm, and some of the reported data is not what the staff is concerned about, which instead affects the analysis efficiency.

[0005] Therefore, it is necessary to provide a positioning detection device and method for arc-drawing leakage in a multi-stage series system. By setting multiple current detection nodes in the circuit, analyzing the current differences at each node and making logical judgments, general leakage detection for AC / DC systems can be achieved, breaking through the limitations of traditional detection methods for DC systems, accurately identifying the faulty section in the multi-stage series system, and improving the efficiency of fault troubleshooting and repair. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a positioning detection device and method for arc-drawing leakage in a multi-stage series system. By setting multiple current detection nodes in the circuit, analyzing the current differences at each node and making logical judgments, general leakage detection for AC / DC systems can be achieved, breaking through the limitations of traditional detection methods for DC systems, accurately identifying the faulty section in the multi-stage series system, and improving the efficiency of fault troubleshooting and repair.

[0007] The technical solution adopted by the present invention is as follows: The present invention includes a current circuit. Current acquisition devices are arranged at both the head end and the tail end of the current circuit. The current value obtained by the current acquisition device at the head end is compared with the current value obtained by the current acquisition device at the tail end. If the difference between the two exceeds a preset threshold, it is determined that an arc-drawing or leakage fault has occurred in the current circuit. By arranging the current acquisition device between the head and the tail of the current circuit, the arc-drawing or leakage fault interval in the current circuit is determined.

[0008] As can be seen from the above solution, the present application has the following advantages: 1. Analysis of current differences at multiple nodes: By setting multiple current detection nodes in the circuit, analyzing the current differences at each node and making logical judgments, general leakage detection for AC / DC systems can be achieved, breaking through the limitations of traditional detection methods for DC systems; 2. Precise positioning of the faulty section: For a multi-stage series system, using the current differences at multiple nodes, the specific section where the fault occurs can be accurately determined, solving the problem that traditional detection cannot locate the faulty section; 3. Dynamic node configuration: Allows flexible setting of detection nodes between any series components / conductor positions. Combining the difference recursion algorithm, the faulty section of systems with different complexities can be located, improving the scalability of the detection system; 4. Adaptive threshold setting: Dynamically adjusts the allowable error range according to parameters such as the detection point spacing, the number of series components in the detection section, the line length, and the system rated current to ensure accurate fault detection under different working conditions.

[0009] In summary, the present application breaks through the limitation of traditional RCD that can only detect the leakage of the total circuit and cannot locate the fault section, realizes the accurate identification of the fault section in the multi-stage series system, improves the efficiency of fault troubleshooting and repair, can be compatible with AC and DC systems, the detection accuracy can be improved to the milliampere level, can detect leakage current of ≥10 mA, and effectively guarantees the safe operation of various electrical systems. Through the multi-node current difference detection scheme, the demand for multi-stage independent detection devices is reduced, and the hardware cost is reduced by about 40%. It supports the segmented detection of the series circuit. Combined with the impedance matching algorithm, the positioning accuracy can reach ±0.5 m, which is suitable for the fault detection and isolation of long-distance lines. The number of detection nodes can be flexibly expanded to meet the detection needs of complex systems such as large-scale energy storage power stations, and can dynamically configure the detection nodes according to the system complexity.

[0010] A preferred solution is that the current loop includes at least two electrically connected components in series, and the current acquisition devices are arranged at the head end of the current loop, the connection points of adjacent electrically connected components, and the end of the current loop, and the current differences of adjacent current detection modules are compared to determine the fault section.

[0011] A preferred solution is that the current loop includes at least three electrically connected components in series, and the current acquisition devices are arranged between or at intervals of adjacent electrically connected components; assuming that the current loop is provided with m current detection nodes (m≥3), the loop is divided into (M - 1) detection segments; the current differences |I_k - I_{k + 1}| of each detection segment are calculated in turn, k = 1, 2,..., m - 1; when the difference of the p-th segment exceeds the corresponding threshold Δ_p, the fault signal of the p-th segment is output; Δ_p is automatically adjusted according to the number of components or the physical length in the detection segment.

[0012] A preferred solution is that the detection method includes the following steps: Step A1: Let the current value obtained by the current acquisition device at the head end be I1, and the current value obtained by the current acquisition device at the end be I2. Step A2: Calculate the absolute value of the difference between I1 and I2, and compare the absolute value with the preset threshold Δ. Step A3: When the absolute value of the difference between I1 and I2 is greater than the preset threshold Δ, that is, |I1 - I2|>Δ, it is determined that an arcing or leakage fault has occurred.

[0013] A preferred solution is that when the current loop is a DC battery pack system, the series structure of the DC battery pack system is positive electrode → battery pack (3 sections) → load → negative electrode; Three groups of the current acquisition devices are respectively arranged at the positive output terminal of the battery pack, the positive electrode of the second battery, and the negative output terminal of the battery pack. The detected value of the positive electrode of the battery pack is I1, the detected value of the positive electrode of the second battery is I2, and the detected value of the negative output terminal of the battery pack is I3; When the second battery has a case leakage, the difference between I1 and I2 exceeds the threshold, and the system locks the fault between the positive output terminal of the battery pack and the positive electrode of the second battery accordingly.

[0014] A preferred solution is that when the current loop is a photovoltaic power generation system, the series structure of the photovoltaic system is photovoltaic string (N components) → input busbar box; The current acquisition device is arranged at the positive electrode of the input busbar box, the positive electrode of the 3rd component, the positive electrode of the 6th component, and the negative electrode of the input busbar box. The detected value of the positive electrode I1 of the input busbar box and the output terminal of the 3rd component is I2, the detected value of the output terminal of the 6th component is I3, and the detected value of the negative electrode of the input busbar box is I4; The normal difference between I1 and I1+n indicates that there is no leakage or arcing in this section. When the difference between I1 and I1+n exceeds the threshold, the system locks the fault in the section between I1 and I1+N accordingly. When the difference between In and In+1 exceeds the threshold within this section, it can be determined that there is leakage or arcing in the section between In and In+1, and further trigger the drone to inspect the line in this section. Description of the Drawings

[0015] Figure 1 [[ID=]15]is the structure diagram of the DC battery pack system; Figure 2 is the structure diagram of the photovoltaic power generation system. Detailed Embodiment

[0016] As Figures 1 to 2 shown, in this embodiment, the present invention includes a current loop. Current acquisition devices are arranged at both the head end and the tail end of the current loop. The current value obtained by the current acquisition device at the head end is compared with the current value obtained by the current acquisition device at the tail end. If the difference between the two exceeds the preset threshold, it is determined that there is an arcing or leakage fault in the current loop. By arranging the current acquisition device between the head and the tail of the current loop, the arcing or leakage fault interval in the current loop is determined. The current difference can be calculated / compared for the acquired signals by using a differential amplifier circuit, or the time stamp can be added to the transmitted data in a wired / wireless manner, and the results are obtained by comparing the data with the same time stamp.

[0017] The current acquisition device includes all types of current acquisition devices that use current transformers, Rogowski coils, Hall sensors, shunt resistors, fluxgate sensors, etc. that can detect current. The current acquisition device can be an independent device / component or can be embedded in the cable during cable production, which is beneficial to improving the applicability of the detection solution.

[0018] As Figures 1 to 2 shown, in this embodiment, the current loop includes at least two serially connected electrical components, devices, or apparatuses. The current acquisition device is provided at the head end of the current loop, at the connection of adjacent electrical components, and at the end of the current loop. By comparing the current differences of adjacent current detection modules, the faulty section can be determined.

[0019] As Figures 1 to 2 shown, in this embodiment, the current loop includes at least three serially connected electrical components, and the current acquisition device is provided between adjacent electrical components or at intervals. Suppose the current loop has m current detection nodes (m≥3), and the loop is divided into (M - 1) detection sections; calculate the current differences |I_k - I_{k + 1}| of each detection section in turn, k = 1,2,...,m - 1; when the difference of the p-th section exceeds the corresponding threshold Δ_p, output the fault signal of the p-th section; Δ_p is automatically adjusted according to the number of components or the physical length in the detection section.

[0020] As Figures 1 to 2 shown, in this embodiment, the detection method includes the following steps: <S Step A1: Let the current value obtained by the current acquisition device at the head end be I1, and the current value obtained by the current acquisition device at the end be I2. Step A2: Calculate the absolute value of the difference between I1 and I2, and compare the absolute value with the preset threshold Δ. Step A3: When the absolute value of the difference between I1 and I2 is greater than the preset threshold Δ, that is, |I1 - I2|>Δ, it is determined that an arcing or leakage fault has occurred.

[0021] As Figure 1 shown, in this embodiment, when the current loop is a DC battery pack system, the series structure of the DC battery pack system is positive electrode → battery pack (3 sections) → load → negative electrode; The current acquisition device is provided at the positive output terminal of the battery pack, the negative electrode of the second battery, and the negative output terminal of the battery pack. The detection value at the positive output terminal of the battery pack is I1, the detection value at the negative electrode of the second battery is I2, and the detection value at the negative output terminal of the battery pack is I3; When the second battery has a leakage in its housing, the difference between I1 and I2 exceeds the threshold, and there is no significant difference between the current values of I2 and I3. Based on this, the system locks the fault between the positive output terminal of the battery pack and the positive electrode of the second battery.

[0022] As Figure 2 shown, in this embodiment, when the current loop is a photovoltaic power generation system, the series structure of the photovoltaic energy storage system is photovoltaic string (N components) → input busbar box; The current acquisition device is arranged at the positive electrode of the input busbar box, the positive electrode of the 3rd component, the positive electrode of the 6th component, and the negative electrode of the input busbar box. The detection value of the positive electrode I1 of the input busbar box and the output terminal of the 3rd component is I2, the detection value of the output terminal of the 6th component is I3, and the detection value of the negative electrode of the input busbar box is I4; If the difference between I1 and I1 + n is normal, it indicates that there is no leakage or arcing in this section; when the difference between I1 and I1 + n exceeds the threshold, the system locks the fault in the section between I1 and I1 + N accordingly. When the difference between In and In + 1 exceeds the threshold within this section, it can be determined that there is leakage or arcing in the section between In and In + 1, and further trigger the drone to inspect the line in this section.

[0023] In this embodiment, for the AC or DC series circuit detected by the current acquisition device, three groups of current acquisition devices are arranged at the head end (I1), the middle node (I2), and the tail end (I3) of the circuit.

[0024] If |I1 - I2| > IΔ → the fault is located between the head end and the middle node; otherwise, the fault is located between the middle node and the tail end.

[0025] The threshold Δ can be dynamically adjusted according to the rated current of the system, and the adjustment range is, for example, 5% - 20%, to adapt to the operation requirements of different systems. The system integrates an alarm output module, which can trigger an audible and visual alarm or control the circuit breaker to act when a fault is detected, timely reminding the staff and cutting off the faulty circuit.

[0026] In this embodiment, in the AC or DC series system, n current detection nodes are set according to actual needs, and the system is divided into (n - 1) detection sections.

[0027] The following positioning logic is adopted: i = 1 - n - 1, if |I_i - I_{i + 1}| > IΔ, it is determined that the i-th section has a fault, and then the detection loop is terminated.

[0028] In this embodiment, the threshold dynamic adjustment algorithm includes, but is not limited to, implementation methods such as formula calculation, look-up table method, AI prediction, etc. The recursive positioning logic of a multi-level system (≥3 detection nodes) defines the fault location methods for different numbers of nodes. The spacing between detection nodes is dynamically configured according to the system topology, for example, by triggering the addition or subtraction of detection points through the battery management system BMS. The fault section location result is transmitted to the upper-level controller through communication methods such as CAN bus, RS485, wireless, etc., and triggers the action of the corresponding branch circuit breaker. It includes a fault history database, and a machine learning model for optimizing the threshold Δ_p, which is beneficial to improving the detection accuracy.

[0029] In this embodiment, the present application is applicable to the detection and fault location of arcing and leakage in AC / DC circuits, especially the fault location scenarios of multi-level AC or DC series systems such as battery packs, photovoltaic arrays, various energy storage systems, etc.

[0030] Although the embodiments of the present invention are described with actual solutions, they do not constitute a limitation on the meaning of the present invention. For those skilled in the art, the modifications of its implementation solutions according to this specification and the combinations with other solutions are obvious.

Claims

1. A positioning and detection device for arcing and leakage in a multi-stage series system, comprising a current loop, characterized in that: Current acquisition devices are provided at both the head end and the tail end of the current loop. The current value obtained by the current acquisition device at the head end is compared with the current value obtained by the current acquisition device at the tail end. If the difference between the two exceeds a preset threshold, it is determined that an arcing or leakage fault has occurred in the current loop; a current acquisition device is provided between the head and the tail of the current loop to determine the section where the arcing or leakage fault in the current loop occurs.

2. The positioning and detection device for arcing and leakage of the multi-stage series system according to claim 1, wherein: The current loop includes at least two electrically connected components in series. Current acquisition devices are provided at the head end of the current loop, at the connection of adjacent electrically connected components, and at the tail end of the current loop. The current differences between adjacent current detection modules are compared to determine the fault section.

3. The positioning and detection device for arcing leakage of the multi-stage series system according to claim 2, wherein: The current loop includes at least three electrically connected components in series. Current acquisition devices are provided between adjacent electrically connected components or at intervals; assume that the current loop has m current detection nodes (m≥3), and the loop is divided into (M - 1) detection sections; calculate the current differences |I_k - I_{k + 1}| of each detection section in turn, k = 1, 2,..., m - 1; when the difference in the p-th section exceeds the corresponding threshold Δ_p, output a fault signal for the p-th section; Δ_p is automatically adjusted according to the number of components or the physical length in the detection section.

4. A detection method for the positioning detection device of the multi-stage series system arc leakage as claimed in claim 3, characterized in that: The detection method includes the following steps: Step A1: Let the current value obtained by the current acquisition device at the head end be I1, and the current value obtained by the current acquisition device at the tail end be I2. Step A2: Calculate the absolute value of the difference between I1 and I2, and compare the absolute value with the preset threshold IΔ. Step A3: When the absolute value of the difference between I1 and I2 is greater than the preset threshold IΔ, that is, |I1 - I2|>IΔ, it is determined that an arcing or leakage fault has occurred.

5. The detection method according to claim 4, wherein: When the current loop is a DC battery pack system, the series structure of the DC battery pack system is positive electrode → battery pack (3 sections) → load → negative electrode; Three groups of current acquisition devices are respectively provided at the positive output terminal of the battery pack, the negative electrode of the second battery, and the negative output terminal of the battery pack. The detected value at the positive output terminal of the battery pack is I1, the detected value at the negative electrode of the second battery is I2, and the detected value at the negative output terminal of the battery pack is I3; When the second battery has a case leakage, the difference between I1 and I2 exceeds the threshold, and there is no obvious difference in the current values of I2 and I3. Based on this, the system locks the fault between the positive output terminal of the battery pack and the positive electrode of the second battery.

6. The detection method according to claim 5, wherein: When the current loop is a photovoltaic power generation system, the series structure of the photovoltaic energy storage system is photovoltaic string (N components) → input busbar box; The current acquisition device is provided at the positive electrode of the input busbar box, the positive electrode of the 3rd component, the positive electrode of the 6th component, and the negative electrode of the input busbar box. The positive electrode of the input busbar box is I1, the detected value at the output terminal of the 3rd component is I2, the detected value at the output terminal of the 6th component is I3, and the detected value at the negative electrode of the input busbar box is I4; If the difference between I1 and I1+n is normal, it indicates that there is no leakage or arcing in this section; when the difference between I1 and I1+n exceeds the threshold, the system locks the fault in the section between I1 and I1+N accordingly. When the difference between In and In+1 exceeds the threshold within this section, it can be determined that there is leakage or arcing in the section between In and In+1, and further trigger the drone to inspect the line in this section.

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