A Y-type loop fault arc locating system and its working method

Abstract

The invention discloses a Y-type loop fault arc locating system in a low-voltage power distribution network environment, comprising a screen display module, a fault arc locating analysis module, a high-speed signal acquisition module, a transmission signal output module, an isolation module, a fault arc generating module, and a power module. The screen display module is electrically connected to the output end of the fault arc locating analysis module, the output end of the fault arc locating analysis module is electrically connected to the input end of the transmission signal output module, the input end of the fault arc locating analysis module is electrically connected to the output end of the high-speed signal acquisition module, the input end of the high-speed signal acquisition module is electrically connected to the isolation module, the output end of the transmission signal output module is electrically connected to the isolation module, the first port of the fault arc generating module is connected to the power module, and the second port is electrically connected to the first load and the second load of the external user through a cable. The invention can quickly respond to the fault arc locating analysis module instruction to perform instruction parsing and high-speed signal acquisition.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical fire monitoring, and more specifically, relates to a Y-type loop fault arc locating system and a working method thereof. Background Art

[0002] Statistics show that 70% of major fires in the country are electrical fires, and more than 80% of electrical fires are caused by fault arcs. Fault arcs are an important cause of electrical fires. The aging of power transmission lines in some old residential areas or long-term illegal overload of electricity in residential buildings can easily lead to the generation of fault arcs, which in turn cause electrical fires.

[0003] At present, there are many studies on the problem of arc fault location in high and medium voltage power transmission systems, while there are relatively few studies on the problem of arc fault location in Y-type circuits in low voltage distribution systems. The main arc fault location methods currently include: (1) arc fault location method based on the physical characteristics of the arc, which uses sensors to detect arc light, arc sound, etc. to achieve location, and is suitable for fixed equipment; (2) impedance method, which measures current and voltage and constructs an impedance model to locate the fault point; (3) traveling wave method, which uses the signal propagation time difference to calculate the fault distance;

[0004] However, the above methods all have some drawbacks that cannot be ignored:

[0005] First, for the arc fault location method based on the physical characteristics of the arc, the radiation range of the physical characteristics is limited, and the environmental conditions must be considered during the implementation process, which makes it difficult to deploy it in a complex low-voltage distribution network structure for arc fault detection;

[0006] Second, the impedance method has made some progress in solving the problem of multi-circuit fault arc location, but it requires the installation of data acquisition equipment on each branch, which increases the complexity and cost of system implementation;

[0007] Third, although the above-mentioned traveling wave method performs well in single-circuit single-load scenarios in low-voltage distribution network environments and has excellent anti-interference ability and positioning accuracy, it currently only supports such scenarios and cannot be applied to multi-circuit fault arc positioning. Summary of the invention

[0008] In view of the above defects or improvement needs of the prior art, the present invention provides a Y-type loop fault arc locating system. Its purpose is to solve the technical problem that the existing arc fault locating method based on the physical characteristics of the arc must take environmental conditions into consideration during implementation, which makes it difficult to deploy it in a complex low-voltage distribution network structure for arc fault detection, and the technical problem that the existing impedance method needs to install a collection device on each branch, which increases the complexity and cost of the system implementation, and the technical problem that the existing traveling wave method only supports a single-loop single-load scenario in a low-voltage distribution network environment, and cannot be applied to multi-loop arc fault locating.

[0009] To achieve the above object, according to one aspect of the present invention, a Y-type loop fault arc locating system is provided, comprising a screen display module, a fault arc locating and analyzing module, a high-speed signal acquisition module, a transmission signal output module, an isolation module, a fault arc generating module, and a power supply module, wherein the screen display module is electrically connected to the output end of the fault arc locating and analyzing module;

[0010] The output end of the fault arc location analysis module is electrically connected to the input end of the transmission signal output module;

[0011] The input end of the fault arc location analysis module is electrically connected to the output end of the high-speed signal acquisition module;

[0012] The input end of the high-speed signal acquisition module is electrically connected to the isolation module;

[0013] The output end of the transmission signal output module is electrically connected to the isolation module;

[0014] The first port of the fault arc generating module is connected to the power supply module, and the second port is electrically connected to a first load and a second load of an external user through a cable.

[0015] The cable comprises a cable trunk and a first cable branch and a second cable branch connected thereto. The first cable branch is electrically connected to a first load, and the second cable branch is electrically connected to a second load.

[0016] Preferably, the transmission signal output module includes an m-sequence generation module, a direct digital frequency synthesizer DDS module, and a digital-to-analog converter DAC module, wherein the DAC module uses an AD9767 digital-to-analog conversion chip with an output signal bandwidth of 10MHz, the DDS module includes a phase accumulator, a phase controller, and a waveform data table ROM, and the m-sequence generation module uses a 6-level linear shift register LSR.

[0017] The isolation module includes two access terminals (P1) and (P2), a matching resistor (R2), a coupling transformer (L1), a withstand voltage capacitor (C1), and a transient suppression diode (D2);

[0018] One end of a first port in a wiring terminal (P1) in the isolation module is electrically connected to an output end of the transmission signal output module and an input end of the high-speed signal acquisition module 3, and a second port is electrically connected to a matching resistor (R2);

[0019] One input end of the coupling transformer (L1) is electrically connected to the other end of the first port in the wiring terminal (P1), and the other input end of the coupling transformer (L1) is electrically connected to the second port in the wiring terminal (P1) through a matching resistor (R2);

[0020] One end of the output of the coupling transformer (L1) is connected to a first port in the wiring terminal (P2) through a withstand voltage capacitor (C1), and the other end of the output is directly electrically connected to a second port in the wiring terminal (P2);

[0021] Two output ends of the coupling transformer (L1) are connected to a transient suppression diode (D2), and a wiring terminal (P2) is electrically connected to a fault arc generation module.

[0022] Preferably, the fault arc locating and analyzing module is used to control the transmitting signal output module to generate a first transmitting signal, the first transmitting signal being a transmitting signal generated by the transmitting signal output module when no fault arc occurs in the fault arc generating module;

[0023] The transmission signal output module is used to send the first transmission signal to the isolation module;

[0024] The isolation module is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the first transmission signal generated by the transmission signal output module can pass through the isolation module unimpeded to reach the fault arc generation module;

[0025] The fault arc generation module is used to reflect the first transmission signal from the isolation module to obtain a first reflection signal, and transmit it to the high-speed signal acquisition module. The high-speed signal acquisition module caches the first reflection signal in the RAM, stores all data in the RAM in the synchronous dynamic random access memory SDRAM, and transmits the first reflection signal to the fault arc location analysis module.

[0026] The isolation module is also used to transmit another part of the first transmission signal generated by the transmission signal output module to the high-speed signal acquisition module without hindrance;

[0027] The high-speed signal acquisition module is also used to cache the first transmission signal from the isolation module in the RAM, store all data cached in the RAM in the SDRAM, and transmit the first transmission signal to the fault arc location analysis module;

[0028] The fault arc location analysis module is also used to perform cross-correlation calculation processing on the first transmission signal from the high-speed signal acquisition module and the processed first reflection signal to obtain a first cross-correlation function spectrum.

[0029] Preferably, the fault arc location analysis module is further used to control the transmission signal output module to generate a second transmission signal, the second transmission signal being the transmission signal generated by the transmission signal output module when a fault arc may occur in the fault arc generation module;

[0030] The transmission signal output module is also used to transmit the generated second transmission signal to the isolation module;

[0031] The isolation module is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the second transmission signal generated by the transmission signal output module can pass through the isolation module unimpeded to reach the fault arc generation module;

[0032] The fault arc generation module is also used to perform reflection processing on the second transmission signal from the isolation module to obtain a second reflection signal, and transmit it to the high-speed signal acquisition module;

[0033] The high-speed signal acquisition module is also used to cache the second reflection signal in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the second reflection signal to the fault arc location analysis module.

[0034] The isolation module is also used to transmit another part of the second transmission signal generated by the transmission signal output module to the high-speed signal acquisition module without hindrance;

[0035] The high-speed signal acquisition module is also used to cache the second transmission signal from the isolation module in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the second transmission signal to the fault arc location analysis module;

[0036] The fault arc location analysis module is also used to perform cross-correlation calculation processing on the second transmission signal and the second reflection signal from the high-speed signal acquisition module to obtain a second cross-correlation function spectrum;

[0037] The fault arc location analysis module is also used to obtain the position of the fault arc on the cable according to the first cross-correlation function map and the second cross-correlation function map, control the power supply module to shut down, and notify the screen display module to output the position of the fault arc on the cable.

[0038] In general, compared with the prior art, the system of the present invention can achieve the following beneficial effects through the above technical solutions conceived by the present invention:

[0039] 1. The system of the present invention is designed with a high-speed signal acquisition module, which is implemented based on FPGA and can quickly respond to the instructions of the fault arc location analysis module, perform instruction parsing and high-speed signal acquisition, and transmit the data to the fault arc location analysis module for calculation and processing after caching through SDRAM, effectively avoiding signal transmission congestion;

[0040] 2. The system of the present invention adopts the AD9226 chip as the ADC module, providing 12-bit sampling accuracy and a maximum sampling rate of 65MSPS, ensuring the accuracy of signal acquisition.

[0041] 3. The system of the present invention adopts a transmission signal output module composed of an m-sequence generation module, a DDS module, and a DAC module, and outputs a cosine signal with a frequency of 5 MHz through 2PSK modulation, thereby ensuring the effective injection of the first transmission signal and the first reflection signal and the accuracy of the system;

[0042] 4. The system of the present invention is designed with an isolation module, which realizes electrical isolation through a coupling transformer, and is configured with a transient suppression diode and a high-voltage capacitor, which effectively prevents interference during signal transmission and enhances the safety and stability of the system;

[0043] 5. The system of the present invention adopts a power supply module. When the system determines that a fault arc occurs, the fault arc location analysis module controls the relay switch of the power supply module to quickly disconnect, thereby reducing the subsequent harm caused by the fault arc.

[0044] According to another aspect of the present invention, there is provided a working method of the above-mentioned Y-type loop fault arc locating system, comprising the following steps:

[0045] (1) The arc fault location analysis module controls the transmission signal output module to output a first transmission signal to the isolation module;

[0046] (2) the isolation module isolates the AC power in the external AC signal, so that a part of the first transmission signal is transmitted to the fault arc generation module through the isolation module, and another part of the first transmission signal is transmitted to the high-speed signal acquisition module;

[0047] (3) The high-speed signal acquisition module transmits the first transmission signal from the isolation module to the fault arc location analysis module;

[0048] (4) The fault arc generation module performs reflection processing on the portion of the first transmission signal from the isolation module to obtain a first reflection signal, and transmits it to the high-speed signal acquisition module.

[0049] (5) The high-speed signal acquisition module transmits the first reflected signal from the fault arc generation module to the fault arc location analysis module;

[0050] (6) The fault arc location analysis module uses a cross-correlation algorithm to process the first transmission signal obtained in step (3) and the first reflection signal obtained in step (5) to obtain a first cross-correlation function graph, and uses the first cross-correlation function graph to respectively derive the lengths of the cable trunk line, the first cable branch line, and the second cable branch line to which the fault arc generation module is connected.

[0051] (7) the fault arc location analysis module controls the transmission signal output module again to output a second transmission signal to the isolation module;

[0052] (8) the isolation module isolates the AC power in the external AC signal, so that a part of the second transmission signal is transmitted to the fault arc generation module through the isolation module, and another part of the second transmission signal is transmitted to the high-speed signal acquisition module;

[0053] (9) The high-speed signal acquisition module transmits the part of the second transmission signal from the isolation module to the fault arc location analysis module;

[0054] (10) The fault arc generation module performs reflection processing on the part of the second transmission signal from the isolation module to obtain a second reflection signal, and transmits it to the high-speed signal acquisition module.

[0055] (11) The high-speed signal acquisition module transmits the second reflected signal from the fault arc generation module to the fault arc location analysis module;

[0056] (12) The fault arc location analysis module 2 uses a cross-correlation algorithm to process the second transmission signal obtained in step (9) and the second reflection signal obtained in step (11) to obtain a second cross-correlation function spectrum, and compares the second cross-correlation function spectrum with the first cross-correlation function spectrum obtained in step (8), and determines whether a fault arc occurs based on the comparison result. If yes, further determine the position X of the fault arc on the cable, and then proceed to step (13), otherwise return to step (7);

[0057] (13) The fault arc location analysis module determines the search range of the abnormal reflection peak on the second cross-correlation function spectrum according to the position X of the fault arc on the cable determined in step (12).

[0058] (14) The fault arc location analysis module records the horizontal coordinate t corresponding to the first abnormal reflection peak from left to right on the second cross-correlation function spectrum according to the search range of the abnormal reflection peak on the second cross-correlation function spectrum determined in step (13). 测量 ;

[0059] (15) The fault arc location analysis module obtains the final location result of the fault arc according to the distance between the position of the fault arc on the cable obtained in step (14) and the output end of the transmission signal output module and the position X obtained in step (12). If the final location result is on the cable trunk line, it means that the fault arc occurs at position X, which is 500 meters away from the connection point S between the cable trunk line and the fault arc generation module. 测量 If the final positioning result is on the first cable branch or the second cable branch, it means that the fault arc occurs at position X, which is S away from the cable trunk. 测量 -M1 meters.

[0060] (16) The fault arc location analysis module displays the final location result obtained in step (15) on the screen display module, and controls the power supply module to shut down, and the process ends.

[0061] Preferably, step (6) is specifically:

[0062] First, a cross-correlation calculation is performed on the first transmission signal and the first reflection signal to obtain a first cross-correlation function spectrum. Then, three peaks with the highest amplitudes are obtained from left to right in the first cross-correlation function spectrum. Then, the horizontal coordinates t1, t2, and t3 corresponding to the three peaks in the first cross-correlation function spectrum are obtained. Then, the sum S1 of the cable trunk length and the length of the second cable branch, the sum S2 of the cable trunk length and the length of the first cable branch, and the sum S3 of the cable trunk length, the second cable branch length, and the first cable branch are calculated by the following formula:

[0063]

[0064] Where V0 represents the transmission speed of the signal in the cable;

[0065] Then, the length M1 of the cable trunk, the length M2 of the first cable branch, and the length M3 of the second cable branch are calculated according to the following formula:

[0066] M1=S1+S2-S3

[0067] M2=S3-S2

[0068] M3=S3-S1.

[0069] Preferably, in step (12), if the peaks corresponding to the lengths S1, S2, and S3 in the second cross-correlation spectrum and the first cross-correlation spectrum completely coincide with each other, it is determined that there is no fault arc on the cable; otherwise, it indicates that there is a fault arc on the cable;

[0070] When the amplitudes of the peaks corresponding to the sum of the three lengths S1, S2, and S3 on the second cross-correlation function spectrum are lower than the peak values ​​of the corresponding peaks on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the cable trunk line;

[0071] When the amplitudes of the peaks corresponding to the sums of the lengths S2 and S3 on the second cross-correlation function spectrum are respectively lower than the peaks of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S1 on the second cross-correlation function spectrum is the same as the peak of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the first cable branch;

[0072] When the amplitudes of the peaks corresponding to the sum of the lengths S1 and S3 on the second cross-correlation function spectrum are respectively lower than the peak values ​​of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S2 on the second cross-correlation function spectrum is the same as the peak value of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the second cable branch.

[0073] Preferably, in step (13), if the position X where the fault arc is located on the cable is located on the cable trunk, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of 0 to M1 meters; if the position X where the fault arc is located on the cable is located on the second cable branch, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of M1 to M1+M2 meters; if the position X where the fault arc is located on the cable is located on the first cable branch, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of M1 to M1+M3 meters.

[0074] Preferably, step (14) is to calculate the distance S between the position of the fault arc on the cable and the output end of the transmission signal output module by the following formula: 测量 :

[0075]

[0076] In general, compared with the prior art, the working method of the present invention can achieve the following beneficial effects through the above technical solutions conceived by the present invention:

[0077] 1. The present invention adopts steps (1) to (5) and steps (8) to (11), which ensures the stability and reliability of the system in a complex network environment by accurately controlling the emission and collection of signals, and realizes effective detection and positioning of fault arcs without being restricted by environmental conditions. Therefore, it can solve the technical problem that the existing fault arc positioning method based on the physical characteristics of the arc must consider environmental conditions during implementation, which makes it difficult to deploy it in a complex low-voltage distribution network structure for fault arc detection;

[0078] 2. The present invention adopts steps (3) to (5) and steps (8) to (10), and its centralized data acquisition process reduces the need to install acquisition equipment on each branch, thereby solving the technical problem that the existing impedance method needs to install acquisition equipment on each branch, which increases the complexity and cost of system implementation;

[0079] 3. The present invention adopts step (6) and step (12) to step (15), so its algorithm can adapt to multi-circuit environment. The Y-type loop cable studied in the present invention is composed of two branch cables. Other more complex circuit structures can be realized by adding more branches or cascading expansion based on the Y-type topology. Therefore, it can solve the technical problem that the existing traveling wave method only supports a single-circuit single-load scenario in a low-voltage distribution network environment, and cannot be applied to multi-circuit fault arc locating.

[0080] 4. The present invention adopts step (6) and step (12) to step (15), and can effectively infer the specific location of the fault point by analyzing the changes in signal reflection and attenuation caused by the occurrence of the fault arc, thereby solving the technical problem of poor positioning accuracy of the existing fault arc positioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a system composition block diagram of the Y-type loop fault arc locating device of the present invention;

[0082] Figure 2 It is a specific flow chart of the working method of the Y-type loop fault arc locating device of the present invention;

[0083] Figure 3 is a specific circuit diagram of the isolation module in the device of the present invention;

[0084] Figure 4 It is a schematic diagram of a Y-loop cable to which the device of the present invention is connected. DETAILED DESCRIPTION

[0085] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0086] like Figure 2 As shown, the present invention provides a Y-type loop fault arc locating system, including a screen display module 1, a fault arc locating and analyzing module 2, a high-speed signal acquisition module 3, a transmission signal output module 4, an isolation module 5, a fault arc generating module 6, and a power supply module 7.

[0087] In the present invention, the arc fault location analysis module 2 adopts the EP4CE10F17 field programmable gate array (FPGA) of Altera Corporation.

[0088] The model of the high-speed signal acquisition module 3 is AD9226.

[0089] The transmission signal output module 4 includes an m-sequence generation module, a direct digital frequency synthesizer (Direct Digital Synthesizer, referred to as DDS) module, and a digital-to-analog converter (Digital-to-Analog Converter, referred to as DAC) module, wherein the DAC module uses the AD9767 digital-to-analog conversion chip with an output signal bandwidth of 10MHz, the DDS module includes a phase accumulator, a phase controller, and a waveform data table ROM, and the m-sequence generation module uses a 6-level linear shift register (Linear Shift Register, referred to as LSR).

[0090] The isolation module 5 includes access terminals P1 and P2, a matching resistor R2, a coupling transformer L1, a withstand voltage capacitor C1, and a transient suppression diode D2; in this example, the resistance of the matching resistor R2 is 50 ohms, the withstand voltage capacitor C1 selects a polypropylene (i.e., CBB) capacitor with a capacitance of 10nF and a withstand voltage of 400V, the ratio between the number of turns of the primary coil and the secondary coil of the coupling transformer L1 is 1:1, and the transient suppression diode D2 selects a 1.5ke12ca-e3 / 54 diode.

[0091] The power module 7 uses the ZH8-63 air switch produced by Jialu Zhujiang Company.

[0092] The screen display module 1 is electrically connected to the output end of the fault arc positioning analysis module 2, the output end of the fault arc positioning analysis module 2 is electrically connected to the input end of the transmission signal output module 4, the input end of the fault arc positioning analysis module 2 is electrically connected to the output end of the high-speed signal acquisition module 3, and the input end of the high-speed signal acquisition module 3 is electrically connected to the isolation module 5. The output end of the transmission signal output module 4 is electrically connected to the isolation module 5.

[0093] like Figure 3 As shown, one end of the first port in the wiring terminal P1 in the isolation module 5 is electrically connected to the output end of the transmission signal output module 4 and the input end of the high-speed signal acquisition module 3, and the second port is electrically connected to the matching resistor R2; one input end of the coupling transformer L1 is electrically connected to the other end of the first port in the wiring terminal P1, and the other input end of the coupling transformer L1 is electrically connected to the second port in the wiring terminal P1 through the matching resistor R2; one end of the output of the coupling transformer L1 is connected to the first port in the wiring terminal P2 through the withstand voltage capacitor C1, and the other end of the output is directly electrically connected to the second port in the wiring terminal P2; the two output ends of the coupling transformer L1 are connected to the transient suppression diode D2, and the wiring terminal P2 is connected to one end of the fault arc generation module 6, the first port of the fault arc generation module 6 is connected to the power module 7, and the second port is electrically connected to the first load and the second load of the external user through a cable. The first load can be a household appliance such as a desk lamp, an electric fan, and a water heater, and the second load can be a household appliance such as a desk lamp, an electric fan, and a water heater, and the first load and the second load can be the same household appliance.

[0094] Specifically, if Figure 4 As shown, the cable includes a cable trunk and a first cable branch and a second cable branch connected thereto. The first cable branch is electrically connected to a first load, and the second cable branch is electrically connected to a second load.

[0095] The fault arc locating and analyzing module 2 is used to control the transmitting signal output module 4 to generate a first transmitting signal, and the transmitting signal output module 4 is used to send the first transmitting signal to the isolation module 5. The isolation module 5 is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the first transmitting signal generated by the transmitting signal output module 4 can pass through the isolation module 5 unimpeded to reach the fault arc generating module 6. The fault arc generating module 6 is used to reflect the first transmitting signal from the isolation module 5 to obtain a first reflected signal, and transmit it to the high-speed signal acquisition module 3. The high-speed signal acquisition module 3 caches the first reflected signal in a random access memory (Random-access memory, referred to as RAM), stores all data in the RAM in a synchronous dynamic random access memory (Synchronous dynamic random-access memory, referred to as SDRAM), and transmits the first reflected signal to the fault arc locating and analyzing module 2.

[0096] In addition, the isolation module 5 is also used to transmit another part of the first transmission signal generated by the transmission signal output module 4 to the high-speed signal acquisition module 3 without hindrance. The high-speed signal acquisition module 3 is used to cache the first transmission signal from the isolation module 5 in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the first transmission signal to the fault arc location analysis module 2.

[0097] The arc fault location analysis module 2 is further used to perform cross-correlation calculation processing on the first transmission signal from the high-speed signal acquisition module 3 and the processed first reflection signal to obtain a first cross-correlation function spectrum.

[0098] The fault arc locating and analyzing module 2 is also used to control the transmitting signal output module 4 to generate a second transmitting signal. The transmitting signal output module 4 is also used to transmit the generated second transmitting signal to the isolation module 5. The isolation module 5 is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the second transmitting signal generated by the transmitting signal output module 4 can pass through the isolation module 5 unimpeded to reach the fault arc generating module 6. The fault arc generating module 6 is used to reflect the second transmitting signal from the isolation module 5 to obtain a second reflected signal, and transmit it to the high-speed signal acquisition module 3. The high-speed signal acquisition module 3 is also used to cache the second reflected signal in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the second reflected signal to the fault arc locating and analyzing module 2.

[0099] In addition, the isolation module 5 is also used to transmit another part of the second transmission signal generated by the transmission signal output module 4 to the high-speed signal acquisition module 3 without hindrance. The high-speed signal acquisition module 3 is used to cache the second transmission signal from the isolation module 5 in the RAM, store all data cached in the RAM in the SDRAM, and transmit the second transmission signal to the fault arc location analysis module 2.

[0100] The arc fault location analysis module 2 performs cross-correlation calculation processing on the second transmission signal and the second reflection signal from the high-speed signal acquisition module 3 to obtain a second cross-correlation function spectrum.

[0101] The fault arc location analysis module 2 is also used to obtain the position of the fault arc on the cable according to the first cross-correlation function map and the second cross-correlation function map, while controlling the power supply module 7 to shut down and notifying the screen display module 1 to output the specific position of the fault arc.

[0102] like Figure 2 As shown, the present invention also provides a working method of the above-mentioned Y-type loop fault arc locating system, comprising the following steps:

[0103] (1) the arc fault location analysis module 2 controls the transmission signal output module 4 to output a first transmission signal to the isolation module 5;

[0104] (2) the isolation module 5 isolates the AC power in the external AC signal, so that a part of the first transmission signal is transmitted to the fault arc generation module 6 through the isolation module 5, and another part of the first transmission signal is transmitted to the high-speed signal acquisition module 3;

[0105] The advantage of this step is that the isolation module 5 isolates the alternating current in the external alternating current signal, effectively preventing interference during the transmission of the first transmission signal, and ensuring the signal strength of the first transmission signal.

[0106] (3) The high-speed signal acquisition module 3 transmits the first transmission signal from the isolation module 5 to the fault arc location analysis module 2;

[0107] (4) The arc fault generation module 6 performs reflection processing on the portion of the first transmission signal from the isolation module 5 to obtain a first reflection signal, and transmits it to the high-speed signal acquisition module 3 .

[0108] Specifically, since the impedance of the load of the external user on the cable does not match the cable impedance, the fault arc generating module 6 generates reflection processing on the first transmission signal to obtain a first reflection signal.

[0109] (5) The high-speed signal acquisition module 3 transmits the first reflected signal from the fault arc generation module 6 to the fault arc location analysis module 2;

[0110] (6) The fault arc location analysis module 2 uses a cross-correlation algorithm to process the first transmission signal obtained in step (3) and the first reflection signal obtained in step (5) to obtain a first cross-correlation function graph, and uses the first cross-correlation function graph to respectively derive the lengths of the cable trunk, the first cable branch, and the second cable branch to which the fault arc generation module 6 is connected.

[0111] Specifically, the fault arc generation module 6 is electrically connected to the external user load through a cable, and the lengths of the cable trunk, the first cable branch, and the second cable branch are recorded as M1, M2, and M3, respectively, in meters. In addition, let S1 be the sum of the length of the cable trunk and the length of the second cable branch, S2 be the sum of the length of the cable trunk and the length of the first cable branch, and S3 be the sum of the length of the cable trunk, the length of the second cable branch, and the length of the first cable branch, that is, S1 = M1 + M2, S2 = M1 + M3, and S3 = M1 + M2 + M3;

[0112] Specifically, this step is as follows: first, a cross-correlation calculation is performed on the first transmission signal and the first reflection signal to obtain a first cross-correlation function spectrum. The first cross-correlation function spectrum is represented by a series of "peaks" with different amplitudes, and its horizontal axis represents the delay time t between the first transmission signal being transmitted from the transmission signal output module 4 and the first reflection signal being received by the high-speed signal acquisition module 3. i , the unit is seconds, the ordinate represents the correlation coefficient a i ; Mutual correlation coefficient a i It is a measure of the similarity between two signals under time delay. Then, the three peaks with the highest amplitudes are obtained from the first cross-correlation function spectrum from left to right. Then, the horizontal coordinates t1, t2, and t3 corresponding to these three peaks in the first cross-correlation function spectrum are obtained. Then, the sum S1 of the cable trunk length and the length of the second cable branch, the sum S2 of the cable trunk length and the length of the first cable branch, and the sum S3 of the cable trunk length, the second cable branch length, and the first cable branch are calculated by the following formula:

[0113]

[0114] Where V0 represents the transmission speed of the signal in the cable, preferably, the size is 2.23×10 8 Meters / second.

[0115] Then, the length M1 of the cable trunk, the length M2 of the first cable branch, and the length M3 of the second cable branch are calculated according to the following formula:

[0116] M1=S1+S2-S3

[0117] M2=S3-S2

[0118] M3=S3-S1

[0119] The advantage of this step is that the structural characteristics of the external cable are analyzed, and the transmission principle of the first transmission signal and the first reflection signal on different cables is used to intuitively obtain the length relationship between the cable trunk, the first cable branch, and the second cable branch in the first cross-correlation spectrum, which is convenient for subsequent fault arc positioning.

[0120] (7) the arc fault location analysis module 2 controls the transmission signal output module 4 again to output a second transmission signal to the isolation module 5;

[0121] (8) The isolation module 5 isolates the AC power in the external AC signal, so that a part of the second transmission signal is transmitted to the fault arc generation module 6 through the isolation module 5, and another part of the second transmission signal is transmitted to the high-speed signal acquisition module 3;

[0122] (9) The high-speed signal acquisition module 3 transmits the part of the second transmission signal from the isolation module 5 to the fault arc location analysis module 2;

[0123] (10) The arc fault generation module 6 performs reflection processing on the portion of the second transmission signal from the isolation module 5 to obtain a second reflection signal, and transmits it to the high-speed signal acquisition module 3 .

[0124] Specifically, the fault arc generating module 6 will reflect the second transmission signal to obtain a second reflection signal because the impedance of the position where the fault arc is located on the cable does not match the impedance of the cable.

[0125] (11) The high-speed signal acquisition module 3 transmits the second reflected signal from the fault arc generation module 6 to the fault arc location analysis module 2;

[0126] (12) The fault arc location analysis module 2 uses a cross-correlation algorithm to process the second transmission signal obtained in step (9) and the second reflection signal obtained in step (11) to obtain a second cross-correlation function spectrum, and compares the second cross-correlation function spectrum with the first cross-correlation function spectrum obtained in step (8), and determines whether a fault arc occurs based on the comparison result. If yes, further determine the position X of the fault arc on the cable, and then proceed to step (13), otherwise return to step (7);

[0127] Specifically, it is first determined whether a fault arc occurs. If the peaks corresponding to S1, S2, and S3 in the second cross-correlation spectrum and the first cross-correlation spectrum completely coincide with each other, it is determined that no fault arc occurs on the cable. Return to step (7) to collect a new second transmission signal and a second reflection signal again, and perform cross-correlation calculation at the fault arc location analysis module 6 to obtain a new second cross-correlation function spectrum, which is then compared with the first cross-correlation function spectrum again.

[0128] If the peaks corresponding to S1, S2, and S3 in the second cross-correlation spectrum and the first cross-correlation spectrum change, specifically, the horizontal coordinate values ​​of the sum of the lengths S1, S2, and S3 before and after the fault arc occurs remain unchanged, so the positions of the peaks corresponding to these elements in the second cross-correlation function spectrum will not change. However, due to the different cable positions of the fault arc, the amplitudes of the peaks corresponding to S1, S2, and S3 will change.

[0129] According to the location of the fault arc, there are three situations:

[0130] (a) When the amplitudes of the peaks corresponding to the sum of the three lengths S1, S2, and S3 on the second cross-correlation function spectrum are lower than the peak values ​​of the corresponding peaks on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the cable trunk line;

[0131] (b) when the amplitudes of the peaks corresponding to the sums of the lengths S2 and S3 on the second cross-correlation function spectrum are significantly lower than the peaks of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S1 on the second cross-correlation function spectrum is substantially the same as the peak of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the first cable branch;

[0132] (c) When the amplitudes of the peaks corresponding to the sums of the lengths S1 and S3 on the second cross-correlation function spectrum are significantly lower than the peaks of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S2 on the second cross-correlation function spectrum is substantially the same as the peak of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the second cable branch;

[0133] The advantage of this step is that by comparing the second cross-correlation function spectrum with the first cross-correlation function spectrum, the change of the peak value in the image and whether an abnormal reflection peak appears can intuitively determine whether a fault arc occurs. If a fault arc occurs, the location of the fault arc can be further obtained.

[0134] (13) The fault arc location analysis module 2 determines the search range of the abnormal reflection peak on the second cross-correlation function spectrum according to the position X of the fault arc on the cable determined in step (12).

[0135] Specifically, compared with the first cross-correlation function graph, the second cross-correlation function graph will also have abnormal reflection peaks (which refers to the peaks that appear on the image of the second cross-correlation function but do not appear on the image of the first cross-correlation function. These peaks are due to the occurrence of a fault arc, which causes reflection and transmission of the second transmission signal when it is transmitted in the cable).

[0136] More specifically, if the position X where the fault arc is located on the cable trunk line, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of 0 to M1 meters; if the position X where the fault arc is located on the cable is located on the second cable branch, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of M1 to M1+M2 meters; if the position X where the fault arc is located on the cable is located on the first cable branch, then the second cross-correlation function map is searched for an abnormal reflection peak whose horizontal coordinate corresponds to a range of M1 to M1+M3 meters.

[0137] The advantage of this step is that it uses the judgment of three different situations in which the fault arc appears in the cable trunk, the first cable branch, and the second cable branch to narrow the search range of the abnormal reflection peak, greatly speed up the search speed and the difficulty of data analysis, and improve the positioning accuracy of the system.

[0138] (14) The arc fault location analysis module 2 records the horizontal coordinate t corresponding to the first abnormal reflection peak from left to right on the second cross-correlation function spectrum according to the search range of the abnormal reflection peak on the second cross-correlation function spectrum determined in step (13). 测量 The distance S between the position of the fault arc on the cable and the output end of the transmitting signal output module is calculated by the following formula: 测量 .

[0139]

[0140] (15) The arc fault location analysis module 2 obtains the final location result of the arc fault according to the distance between the position of the arc fault on the cable and the output end of the transmission signal output module obtained in step (14) and the position X obtained in step (12). If the final location result is on the cable trunk line, it means that the arc fault occurs at position X, which is 50 meters away from the connection point S between the cable trunk line and the arc fault module. 测量 If the final positioning result is on the first cable branch or the second cable branch, it means that the fault arc occurs at position X, which is S away from the cable trunk. 测量 -M1 meters.

[0141] (16) The fault arc positioning analysis module 2 displays the final positioning result obtained in step (15) on the screen display module 1, and at the same time controls the air switch of the power module to disconnect, and the process ends.

[0142] The advantage of this step is that the arc fault location analysis module 2 will immediately control the air switch of the power module to disconnect after determining that an arc fault has occurred, thereby reducing the more serious fire hazards that may be caused by the arc fault on the cable.

[0143] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0144] In summary, through the above description of the present invention, the main advantages of the present invention include:

[0145] 1. The system is designed with cost-effectiveness in mind, significantly reducing economic costs and system complexity. At the same time, the system has a user-friendly interface and uses a self-developed graphical user interface to simplify the operating process and improve the practicality and convenience of the system.

[0146] 2. It has strong adaptability and can adapt to different power usage scenarios. The data collection function provides data support for continuous algorithm optimization and system upgrades, ensuring the long-term effectiveness of the system and its ability to adapt to future technological developments.

[0147] 3. The system structure is flexible and scalable, and can easily achieve the expansion of more complex circuit structures based on the Y-type multi-loop circuit topology.

[0148] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A working method of a Y-type loop fault arc locating system, the Y-type loop fault arc locating system comprises a screen display module, a fault arc locating analysis module, a high-speed signal acquisition module, a transmission signal output module, an isolation module, a fault arc generating module, and a power module, the screen display module is electrically connected to the output end of the fault arc locating analysis module; the output end of the fault arc locating analysis module is electrically connected to the input end of the transmission signal output module; the input end of the fault arc locating analysis module is electrically connected to the output end of the high-speed signal acquisition module; the input end of the high-speed signal acquisition module is electrically connected to the isolation module; the output end of the transmission signal output module is electrically connected to the isolation module; the first port of the fault arc generating module is connected to the power module, and the second port is electrically connected to the first load and the second load of the external user through a cable; the cable comprises a section of a cable trunk and a first cable branch and a second cable branch connected thereto, the first cable branch is electrically connected to the first load, and the second cable branch is electrically connected to the second load, characterized in that The working method comprises the following steps: (1) The arc fault location analysis module controls the transmission signal output module to output a first transmission signal to the isolation module; (2) the isolation module isolates the AC power in the external AC signal, so that a part of the first transmission signal is transmitted to the fault arc generation module through the isolation module, and another part of the first transmission signal is transmitted to the high-speed signal acquisition module; (3) The high-speed signal acquisition module transmits the first transmission signal from the isolation module to the fault arc location analysis module; (4) the arc fault generation module performs reflection processing on the portion of the first transmission signal from the isolation module to obtain a first reflection signal, and transmits the first reflection signal to the high-speed signal acquisition module; (5) The high-speed signal acquisition module transmits the first reflected signal from the fault arc generation module to the fault arc location analysis module; (6) The fault arc location analysis module uses a cross-correlation algorithm to process the first transmission signal obtained in step (3) and the first reflection signal obtained in step (5) to obtain a first cross-correlation function spectrum, and obtains the cable trunk length, the first cable branch length, and the second cable branch length to which the fault arc generation module is connected through the first cross-correlation function spectrum; (7) the fault arc location analysis module controls the transmission signal output module again to output a second transmission signal to the isolation module; (8) the isolation module isolates the AC power in the external AC signal, so that a part of the second transmission signal is transmitted to the fault arc generation module through the isolation module, and another part of the second transmission signal is transmitted to the high-speed signal acquisition module; (9) The high-speed signal acquisition module transmits the part of the second transmission signal from the isolation module to the fault arc location analysis module; (10) the arc fault generation module performs reflection processing on the part of the second transmission signal from the isolation module to obtain a second reflection signal, and transmits the second reflection signal to the high-speed signal acquisition module; (11) The high-speed signal acquisition module transmits the second reflected signal from the fault arc generation module to the fault arc location analysis module; (12) The fault arc location analysis module (2) uses a cross-correlation algorithm to process the second transmission signal obtained in step (9) and the second reflection signal obtained in step (11) to obtain a second cross-correlation function spectrum, and compares the second cross-correlation function spectrum with the first cross-correlation function spectrum obtained in step (8), and determines whether a fault arc occurs based on the comparison result. If yes, further determine the position X of the fault arc on the cable, and then proceed to step (13), otherwise return to step (7); (13) The fault arc location analysis module determines the search range of the abnormal reflection peak on the second cross-correlation function spectrum according to the position X of the fault arc on the cable determined in step (12); (14) The fault arc location analysis module records the horizontal coordinate t corresponding to the first abnormal reflection peak from left to right on the second cross-correlation function spectrum according to the search range of the abnormal reflection peak on the second cross-correlation function spectrum determined in step (13). 测量 ; (15) The fault arc positioning analysis module obtains the final positioning result of the fault arc according to the distance between the position of the fault arc on the cable obtained in step (14) and the output end of the transmitting signal output module and the position X obtained in step (12); if the final positioning result is on the cable trunk line, it means that the fault arc occurs at position X, which is 500 meters away from the connection point S between the cable trunk line and the fault arc generation module. 测量 If the final positioning result is on the first cable branch or the second cable branch, it means that the fault arc occurs at position X, which is S away from the cable trunk. 测量 -M1 meters; (16) The fault arc location analysis module displays the final location result obtained in step (15) on the screen display module, and controls the power supply module to shut down, and the process ends.

2. The working method of the Y-type loop fault arc locating system according to claim 1, characterized in that: Step (6) is specifically as follows: First, a cross-correlation calculation is performed on the first transmission signal and the first reflection signal to obtain a first cross-correlation function spectrum, and then the three peaks with the highest amplitudes are obtained from the first cross-correlation function spectrum from left to right, and then the horizontal coordinates t1, t2, and t3 corresponding to the three peaks in the first cross-correlation function spectrum are obtained, and then the sum S1 of the cable trunk length and the second cable branch length, the sum S2 of the cable trunk length and the first cable branch length, and the sum S3 of the cable trunk length, the second cable branch length, and the first cable branch length are calculated by the following formulas: Where V0 represents the transmission speed of the signal in the cable; Then, the cable trunk length M1, the first cable branch length M2, and the second cable branch length M3 are calculated according to the following formula: M1=S1+S2-S3 M2=S3-S1 M3=S3-S2.

3. The working method of the Y-type loop fault arc locating system according to claim 2, characterized in that: In step (12), if the peaks corresponding to the lengths S1, S2, and S3 in the second cross-correlation function spectrum and the first cross-correlation function spectrum completely coincide with each other, it is determined that there is no fault arc on the cable; otherwise, it is determined that there is a fault arc on the cable; When the amplitudes of the peaks corresponding to the sum of the three lengths S1, S2, and S3 on the second cross-correlation function spectrum are lower than the peak values ​​of the corresponding peaks on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the cable trunk line; When the amplitudes of the peaks corresponding to the sums of the lengths S2 and S3 on the second cross-correlation function spectrum are respectively lower than the peaks of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S1 on the second cross-correlation function spectrum is the same as the peak of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the first cable branch; When the amplitudes of the peaks corresponding to the sum of the lengths S1 and S3 on the second cross-correlation function spectrum are respectively lower than the peak values ​​of the corresponding peaks on the first cross-correlation function spectrum, and the amplitude of the peak corresponding to the sum of the lengths S2 on the second cross-correlation function spectrum is the same as the peak value of the corresponding peak on the first cross-correlation function spectrum, it is determined that the position X of the fault arc on the cable is located on the second cable branch.

4. The working method of the Y-type loop fault arc locating system according to claim 3 is characterized in that: In step (13), if the position X where the fault arc is located on the cable is on the cable trunk, then search for an abnormal reflection peak whose horizontal coordinate corresponds to a range of 0 to M1 meters on the second cross-correlation function spectrum; If the position X where the fault arc is located on the cable is located on the second cable branch, then the second cross-correlation function spectrum is searched for an abnormal reflection peak whose horizontal coordinate corresponds to the range of M1 to M1+M2 meters; if the position X where the fault arc is located on the cable is located on the first cable branch, then the second cross-correlation function spectrum is searched for an abnormal reflection peak whose horizontal coordinate corresponds to the range of M1 to M1+M3 meters.

5. The working method of the Y-type loop fault arc locating system according to claim 4, characterized in that: Step (14) is to calculate the distance S between the position of the fault arc on the cable and the output end of the transmitting signal output module by the following formula: 测量 :

6. The working method of the Y-type loop fault arc locating system according to claim 1, characterized in that: The transmission signal output module includes an m-sequence generation module, a direct digital frequency synthesizer DDS module, and a digital-to-analog converter DAC module, wherein the DAC module uses an AD9767 digital-to-analog conversion chip with an output signal bandwidth of 10MHz, the DDS module includes a phase accumulator, a phase controller, and a waveform data table ROM, and the m-sequence generation module uses a 6-level linear shift register LSR; The isolation module includes two wiring terminals (P1) and (P2), a matching resistor (R2), a coupling transformer (L1), a withstand voltage capacitor (C1), and a transient suppression diode (D2); One end of a first port in a wiring terminal (P1) in the isolation module is electrically connected to an output end of a transmission signal output module and an input end of a high-speed signal acquisition module (3), and a second port is electrically connected to a matching resistor (R2); One input end of the coupling transformer (L1) is electrically connected to the other end of the first port in the wiring terminal (P1), and the other input end of the coupling transformer (L1) is electrically connected to the second port in the wiring terminal (P1) through a matching resistor (R2); One end of the output of the coupling transformer (L1) is connected to a first port in the wiring terminal (P2) through a withstand voltage capacitor (C1), and the other end of the output is directly electrically connected to a second port in the wiring terminal (P2); Two output ends of the coupling transformer (L1) are connected to a transient suppression diode (D2), and a wiring terminal (P2) is electrically connected to a fault arc generation module.

7. The working method of the Y-type loop fault arc locating system according to claim 6, characterized in that: The fault arc location analysis module is used to control the transmission signal output module to generate a first transmission signal; The transmission signal output module is used to send the first transmission signal to the isolation module; The isolation module is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the first transmission signal generated by the transmission signal output module can pass through the isolation module unimpeded to reach the fault arc generation module; The fault arc generation module is used for performing reflection processing on the first transmission signal from the isolation module to obtain a first reflection signal, and transmit it to the high-speed signal acquisition module, the high-speed signal acquisition module caches the first reflection signal in the RAM, stores all data in the RAM in the synchronous dynamic random access memory SDRAM, and transmits the first reflection signal to the fault arc location analysis module; The isolation module is also used to transmit another part of the first transmission signal generated by the transmission signal output module to the high-speed signal acquisition module without hindrance; The high-speed signal acquisition module is also used to cache the first transmission signal from the isolation module in the RAM, store all data cached in the RAM in the SDRAM, and transmit the first transmission signal to the fault arc location analysis module; The fault arc location analysis module is also used to perform cross-correlation calculation processing on the first transmission signal from the high-speed signal acquisition module and the processed first reflection signal to obtain a first cross-correlation function spectrum.

8. The working method of the Y-type loop fault arc locating system according to claim 7, characterized in that: The fault arc location analysis module is also used to control the transmission signal output module to generate a second transmission signal; The transmission signal output module is also used to transmit the generated second transmission signal to the isolation module; The isolation module is connected to an external AC signal of 220V, 50HZ, and is used to isolate the AC in the external AC signal, so that a part of the second transmission signal generated by the transmission signal output module can pass through the isolation module unimpeded to reach the fault arc generation module; The fault arc generation module is also used to perform reflection processing on the second transmission signal from the isolation module to obtain a second reflection signal, and transmit it to the high-speed signal acquisition module; The high-speed signal acquisition module is also used to cache the second reflected signal in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the second reflected signal to the fault arc location analysis module; The isolation module is also used to transmit another part of the second transmission signal generated by the transmission signal output module to the high-speed signal acquisition module without hindrance; The high-speed signal acquisition module is also used to cache the second transmission signal from the isolation module in the RAM, store all the data cached in the RAM in the SDRAM, and transmit the second transmission signal to the fault arc location analysis module; The fault arc location analysis module is also used to perform cross-correlation calculation processing on the second transmission signal and the second reflection signal from the high-speed signal acquisition module to obtain a second cross-correlation function spectrum; The fault arc location analysis module is also used to obtain the position of the fault arc on the cable according to the first cross-correlation function map and the second cross-correlation function map, control the power supply module to shut down, and notify the screen display module to output the position of the fault arc on the cable.

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