Current type electric leakage detection device and detection method thereof

Abstract

The invention belongs to the technical field of line electric leakage detection, and discloses a current type electric leakage detection device and a detection method thereof.The current type electric leakage detection device comprises a mobile control terminal and at least two signal acquisition cards, and the mobile control terminal is in networking communication with all the signal acquisition cards; at least one signal acquisition card serves as a pulse sending unit, and the pulse sending unit is connected into the power line through a signal interface and injects current pulses into the power line; at least one signal acquisition card serves as a pulse receiving unit, and the pulse receiving unit is connected to a power line through a signal interface of the pulse receiving unit and directly detects flowing current pulse; according to the invention, the fast transient current pulse at the nanosecond leading edge is used as a detection signal, and the measurement resolution of the line length and the fault point can be improved within 1 meter by measuring the unidirectional propagation time delay of the pulse between two known points with high precision; the precision level can meet the precise fixed-point requirements of short-distance and multi-branch complex lines such as families, offices and the like.

Description

Technical Field

[0001] This invention relates to the field of line leakage detection technology, and in particular to a current-type leakage detection device and its detection method. Background Technology

[0002] With the development of power grids, numerous detection schemes and equipment, such as fault indicators, substation detection schemes, and monitoring terminals, have been widely deployed in power generation, substation, transmission, and distribution, enabling real-time perception and fault location of the main power grid components. However, at the very end of the power grid—the low-voltage user side—especially in the internal wiring of homes and buildings, the application of fault detection and precise location technologies remains very limited. This is mainly due to two factors: firstly, to protect users' property and privacy, it is difficult to uniformly and permanently install monitoring equipment in thousands of households; secondly, the user-side wiring environment is complex, with many branches and short distances, requiring extremely high positioning accuracy, while the cost of deploying traditional fixed monitoring systems is too high. Therefore, mobile fault analysis equipment is the only option for fault analysis of household wiring.

[0003] For example, the invention patent with publication number CN118818204A discloses a method for locating leakage current in low-voltage users. This method relies on voltage signals for carrier communication on power lines. However, the strong power frequency voltage and its harmonics on power lines generate severe coupling interference, forcing the device to adopt avoidance strategies such as voltage zero-crossing triggering, which greatly limits its usability and real-time performance. More importantly, the modulation, demodulation, and propagation of the communication signal by the coupling transformer introduce inherent delays at the microsecond level, resulting in a final calculated cable length resolution on the order of tens of meters, completely failing to meet the precise location requirements of short, few-meter-long lines within a household.

[0004] Most other alternative solutions use leakage current detection kits consisting of an insulation resistance tester, a leakage current clamp meter, and a line tracing instrument. Their location relies on manual experience to check each section one by one, which requires high professional skills from the operators, is inefficient, and is difficult to popularize.

[0005] Furthermore, some advanced positioning technologies applied to power distribution networks, such as multi-sensor data fusion online monitoring systems and step-frequency wave reflection methods, although based on different principles, are all designed for long-distance, online monitoring of high-voltage / medium-voltage transmission lines. These systems are typically complex in structure, costly, require fixed installation and continuous power supply, and their positioning accuracy is only in the range of ten to one hundred meters. They cannot be directly adapted to user-side low-voltage, power outage, short-distance, high-precision on-site rapid maintenance scenarios. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the purpose of this invention is to provide a current-type leakage current detection device to solve the above-mentioned technical problems.

[0007] To achieve this objective, the present invention adopts the following technical solution: On the one hand, the present invention provides a current-type leakage current detection device, including a mobile control terminal and at least two signal acquisition cards, wherein the mobile control terminal communicates with all the signal acquisition cards in a network and coordinates their control. At least one of the signal acquisition cards serves as a pulse transmission unit, which connects to the power line through its signal interface and injects current pulses into the power line. At least one of the signal acquisition cards serves as a pulse receiving unit. The pulse receiving unit is connected to the power line through its signal interface to provide a DC bias to ground for the power line and directly detect the current pulses flowing through it. The mobile control terminal is used to collect the propagation delay of the current pulse from the pulse transmitting unit to the pulse receiving unit and to calculate the location of the leakage fault point.

[0008] As a preferred embodiment of a current-type leakage current detection device, the signal acquisition card includes a system-on-a-chip, a wireless communication module, an analog-to-digital converter, a digital-to-analog converter, and a transmitting / receiving circuit. The system-on-a-chip is connected to the wireless communication module, the analog-to-digital converter, and the digital-to-analog converter, respectively. The transmitting / receiving circuit is connected between the output terminal of the digital-to-analog converter and the input terminal of the analog-to-digital converter, and is provided with a signal interface for accessing the line.

[0009] As a preferred embodiment of a current-type leakage current detection device, the transmitting / receiving circuit includes an operational amplifier U1, a transistor Q1, a current sensing resistor R1, a current sensing resistor R2, a switch S1, and a current sensing amplifier U2. The non-inverting input of the operational amplifier U1 is connected to the output of the digital-to-analog converter, and the output of the operational amplifier U1 is connected to the base of the transistor Q1. The emitter of the transistor Q1 is connected to the first terminal of the current sensing resistor R1, the second terminal of the current sensing resistor R1 is grounded, and the inverting input terminal of the operational amplifier U1 is connected to the emitter of the transistor Q1 to form negative feedback for voltage-to-current conversion. The collector of transistor Q1, the inverting input of current-sensing amplifier U2, and one end of switch S1 are all connected to the first end of current-sensing resistor R2; the second end of current-sensing resistor R2 is connected to the power line interface and the non-inverting input of current-sensing amplifier U2; the output of current-sensing amplifier U2 is connected to the input of analog-to-digital converter. The other end of the switch S1 is connected to the power supply voltage.

[0010] As a preferred embodiment of a current-type leakage current detection device, the transmitting / receiving circuit has two operating modes: transmitting and receiving. The system-on-a-chip controls the switching of the transmitting mode and the receiving mode by controlling the on / off state of the switch S1 and the output of the digital-to-analog converter. When the transmitting / receiving circuit switches to transmitting mode, the switch S1 is opened, and the system-on-a-chip controls the digital-to-analog converter to output a specific voltage waveform. Through the negative feedback loop formed by the operational amplifier U1 and the transistor Q1, the voltage signal is converted into a current pulse proportional to the voltage waveform. The current pulse flows out from the collector of the transistor Q1 and is injected into the power line through the current sensing resistor R2. When the transmitting / receiving circuit switches to receiving mode, the switch S1 is closed, the digital-to-analog converter outputs a low level to turn off the transistor Q1, and the power line interface is clamped to a potential close to the power supply voltage through the current sensing resistor R2 and the switch S1 to provide DC bias; the current pulse flowing through the power line generates a voltage drop across the current sensing resistor R2, which is amplified by the current sensing amplifier U2 and output to the analog-to-digital converter.

[0011] As a preferred embodiment of a current-type leakage current detection device, the mobile control terminal communicates and synchronizes commands with each of the signal acquisition cards via a wireless local area network hotspot.

[0012] As a preferred embodiment of a current-type leakage current detection device, the wireless communication module is one of WIFI, Zigbee, or Bluetooth.

[0013] As a preferred embodiment of the current-type leakage current detection device, both the mobile control terminal and the signal acquisition card are equipped with built-in batteries, which power them.

[0014] On the other hand, the present invention also provides a current-type leakage current detection method, comprising the following steps: S1. The mobile control terminal establishes a wireless communication connection with at least two signal acquisition cards; S2. Connect at least two of the signal acquisition cards to different points on the power line, and configure one of the signal acquisition cards as a pulse transmitting unit and the other signal acquisition card as a pulse receiving unit through the mobile control terminal. S3. The mobile control terminal controls the pulse transmitting unit to inject current pulses into the power line; S4. The mobile control terminal controls the pulse receiving unit to provide a DC bias to ground for the power line and simultaneously detects the current pulses flowing through it. S5. The mobile control terminal calculates and determines the location of the leakage fault point based on the propagation delay of the current pulse from the pulse transmitting unit to the pulse receiving unit.

[0015] As a preferred embodiment of the current-type leakage current detection method, step S3 specifically includes: The mobile control terminal controls the switch S1 of the pulse transmitting unit to open and controls its digital-to-analog converter to output a specific voltage waveform. Through the negative feedback loop formed by the operational amplifier U1 and the transistor Q1, a current pulse proportional to the voltage waveform is generated. This current pulse is injected into the power line from the collector of the transistor Q1 through the current sensing resistor R2.

[0016] As a preferred embodiment of the current-type leakage current detection method, step S4 specifically includes: The mobile control terminal controls the switch S1 of the pulse receiving unit to close, and simultaneously controls its digital-to-analog converter to output a low level to turn off the transistor Q1. The power line interface is clamped to a potential close to the power supply voltage through the current sensing resistor R2 and the switch S1 to provide DC bias. The current pulse flowing through the power line generates a voltage drop across the current sensing resistor R2, which is amplified by the current sensing amplifier U2, sampled by the analog-to-digital converter, and sent to the system-on-a-chip for processing.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention abandons the carrier communication scheme and creatively adopts the nanosecond-level leading fast transient current pulse as the detection signal. By measuring the one-way propagation delay of the pulse between two known points with high precision, and combining the known wave speed of the signal in the power line, the measurement resolution of the line length and the fault point can be improved to within 1 meter. This level of precision can meet the precise positioning requirements of short-distance, multi-branch complex lines such as homes and offices.

[0018] (2) The present invention uses current pulse as a feature signal for transmission and detection. Current pulse can effectively avoid the influence of power frequency voltage coupling and various voltage-type electromagnetic noise that are common on power lines. At the same time, the receiving end provides DC bias through a unique circuit design, which can quickly discharge the residual coupling voltage on the line. This makes the detection waveform clear and distortion-free even in complex power environments, effectively preventing false triggering and improving the accuracy of leakage detection.

[0019] (3) The transmitting / receiving circuit of the present invention is ingeniously designed. Through a single switch control, the same circuit can function as a high-precision programmable current source in transmitting mode and as a high-sensitivity current detector in receiving mode. This hardware multiplexing design greatly simplifies the circuit structure and reduces equipment costs.

[0020] (4) All devices of the present invention are powered by batteries, and the circuit under test is required to be completely de-energized during testing. This fundamentally eliminates the risk of electric shock that may be caused by online testing, which is particularly suitable for maintenance scenarios after a circuit breaker trips due to a leakage fault in a household. At the same time, the de-energized environment also avoids strong electrical interference, reduces the stringent requirements on the insulation level of the equipment, and makes the device design simpler and the cost lower. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a network diagram of the mobile control terminal and signal acquisition card described in this invention.

[0023] Figure 2 This is a schematic diagram of the signal acquisition card module described in this invention.

[0024] Figure 3 This is a circuit diagram of the transmitting / receiving circuit described in this invention.

[0025] Figure 4 This is a circuit diagram of the pulse transmitting unit and the pulse receiving unit described in this invention.

[0026] Figure 5 This is a circuit diagram of the analog-to-digital converter described in this invention.

[0027] Figure 6 This is a circuit diagram of the digital-to-analog converter described in this invention.

[0028] Figure 7 This is a schematic diagram of the structure of the signal acquisition card of the present invention connected to the power line.

[0029] Figure 8 This is a noise diagram of the voltage-mode detection method used in existing technologies.

[0030] Figure 9 This is a noise diagram of the current-mode detection method used in this invention.

[0031] Explanation of reference numerals in the attached figures: 1. Mobile control terminal; 2. Signal acquisition card; 21. System-on-a-chip; 22. Wireless communication module; 23. Analog-to-digital converter; 24. Digital-to-analog converter; 25. Transmitting / receiving circuit. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Example 1: like Figure 1 As shown, this embodiment provides a current-type leakage current detection device, which can be used to accurately locate leakage current faults in low-voltage user circuits under power outage conditions. The device includes a mobile control terminal 1 and two signal acquisition cards 2. Each signal acquisition card 2 is connected to the power line through a signal interface, and the mobile control terminal 1 communicates with all the signal acquisition cards 2 in a network.

[0037] In this embodiment, the mobile control terminal 1 is preferably a mobile computer with control and analysis host computer software, which has a built-in wireless network card and creates a WIFI hotspot. After each signal acquisition card 2 is powered on, it automatically searches for and connects to the hotspot, realizing data interaction and command synchronization with the mobile control terminal 1.

[0038] It is understood that the mobile control terminal 1 is not limited to a mobile computer, but may also be other terminals capable of running relevant analysis and control host computer software. The wireless communication method of the mobile control terminal 1 is not limited to WIFI, but may also be other wireless local area network technologies such as ZigBee and Bluetooth.

[0039] In this embodiment, both the mobile control terminal 1 and the signal acquisition card 2 are portable devices powered by built-in batteries. The entire detection process can be carried out in a safe environment with the line completely powered off. This fundamentally eliminates the risk of electric shock that may be caused by online detection, which is particularly suitable for maintenance scenarios after a circuit breaker trips due to a household leakage fault. At the same time, the power-off environment also avoids strong electrical interference, reduces the stringent requirements on the insulation level of the equipment, and simplifies the device design and reduces costs.

[0040] The core function of the mobile control terminal 1 is coordination and control. It provides a graphical user interface through host computer software. Users can view all online signal acquisition cards 2 on the interface and designate any two of them as pulse transmitting unit and pulse receiving unit, respectively. The mobile control terminal 1 can issue working mode commands to the designated signal acquisition card 2. The signal acquisition card 2 acting as the pulse transmitting unit injects current pulses into the power line, and the signal acquisition card 2 acting as the pulse receiving unit provides DC bias to ground for the power line and directly detects the current pulses flowing through it. The mobile control terminal 1 collects the propagation delay of the current pulse from the pulse transmitting unit to the pulse receiving unit, calculates the location of the leakage fault point, and finally displays the results intuitively to the user.

[0041] like Figure 2 As shown, the signal acquisition card 2 in this embodiment specifically includes a system-on-a-chip 21, a wireless communication module 22, an analog-to-digital converter 23, a digital-to-analog converter 24, and a transmitting / receiving circuit 25; The system-on-a-chip 21 is the control core of the signal acquisition card 2. It can be an embedded chip that integrates a processor, memory and peripheral interface, such as the XC7Z020 chip. The system-on-a-chip 21 is connected to the wireless communication module 22, the analog-to-digital converter 23 and the digital-to-analog converter 24 respectively. It is responsible for communicating with the mobile control terminal 1 through the wireless communication module 22, receiving and executing instructions.

[0042] like Figure 5 As shown, the analog-to-digital converter 23 preferably uses the AD9643 chip, which has a sampling rate of up to 250Msps, providing a hardware foundation for achieving nanosecond-level time resolution.

[0043] like Figure 6 As shown, the digital-to-analog converter 24 preferably uses the AD9122 chip, which can output a high-resolution differential current signal for generating precisely timed pulse waveforms.

[0044] The transmitting / receiving circuit 25 is the key hardware for realizing the core function of the present invention. The transmitting / receiving circuit 25 is connected between the output terminal of the digital-to-analog converter 24 and the input terminal of the analog-to-digital converter 23, and is provided with a signal interface for connecting to the line, for connecting to the power line under test.

[0045] like Figure 3 As shown, the transmitting / receiving circuit 25 specifically includes an operational amplifier U1, a transistor Q1, a current sensing resistor R1, a current sensing resistor R2, a switch S1, and a current sensing amplifier U2; The non-inverting input of operational amplifier U1 is connected to the output of digital-to-analog converter 24, and the output of operational amplifier U1 is connected to the base of transistor Q1. The emitter of transistor Q1 is connected to the first end of current sensing resistor R1, the second end of current sensing resistor R1 is grounded, and the inverting input of operational amplifier U1 is connected to the emitter of transistor Q1 to form negative feedback for voltage-to-current conversion. The collector of transistor Q1, the inverting input of current-sensing amplifier U2, and one end of switch S1 are all connected to the first end of current-sensing resistor R2; the second end of current-sensing resistor R2 is connected to the power line interface and the non-inverting input of current-sensing amplifier U2; the output of current-sensing amplifier U2 is connected to the input of analog-to-digital converter 23. The other end of switch S1 is connected to the power supply voltage.

[0046] like Figure 4 As shown, the transmit / receive circuit 25 has two operating modes: transmit and receive. The system-on-a-chip 21 controls the switching between transmit and receive modes by controlling the on / off state of switch S1 and the output of the digital-to-analog converter 24. This allows the same circuit to function as a high-precision programmable current source in transmit mode and as a high-sensitivity current detector in receive mode. This hardware multiplexing design greatly simplifies the circuit structure and reduces equipment costs.

[0047] When the transmit / receive circuit 25 switches to transmit mode, the control switch S1 is first opened, and then the system-on-a-chip 21 controls the digital-to-analog converter 24 to output a specific voltage waveform, such as a Gaussian pulse. This voltage signal is amplified by the operational amplifier U1 and drives the base of the transistor Q1, converting the voltage signal into a current pulse proportional to the voltage wave. This current pulse flows out from the collector of the transistor Q1 and is injected into the power line through the current sensing resistor R2. When the transmitting / receiving circuit 25 switches to receive mode, it first controls the digital-to-analog converter 24 to output a low level, causing the operational amplifier U1 to output a low level and the transistor Q1 to be cut off, thus preventing the power line from conducting to ground. Simultaneously, it controls the switch S1 to close, clamping the power line interface to a potential close to the power supply voltage through the current-sensing resistor R2 and switch S1. This results in low impedance to ground for the entire line, allowing the coupling voltage to be quickly discharged. Due to the low power of the coupling voltage, there is virtually no current in the power line, therefore there is no voltage drop across the current-sensing resistor R2, providing a stable DC bias (high potential) for the entire test circuit. When the current pulse injected by the pulse transmitting unit propagates along the power line to the pulse receiving unit, the current flows sequentially through the current-sensing resistor R2, switch S1, and power supply VCC, completing one current-mode signal transmission. A voltage drop is generated when the current flows through the current-sensing resistor R2, and this voltage drop is amplified by the current-sensing amplifier U2. The amplified signal is then output to the analog-to-digital converter 23 and sampled at high speed. The system-on-a-chip 21 records the precise moment when the analog-to-digital converter 23 first exceeds the preset threshold as the signal arrival time.

[0048] In low-voltage line environments with power outages and low impedance to ground, traditional voltage signal-based detection methods are highly susceptible to interference from distributed capacitance coupling. The fundamental reason is that voltage detection relies on measuring the potential difference at high-impedance nodes, while the distributed capacitance C between the cable and ground... g This provides a coupling path for spatial electromagnetic noise (such as power frequency and its harmonics). According to the current formula... Noise voltage changes will generate coupling current. This generates a significant interference voltage across the high input impedance of the detection circuit, severely drowning out the useful signal.

[0049] This embodiment overcomes this problem in principle through an innovative combination of current pulse injection and active clamping of VCC at the receiving end. During the receiving preparation phase, the pulse receiving unit closes switch S1, forcibly clamping the power line to the power supply voltage VCC through the current sensing resistor R2. This results in an extremely low AC impedance to ground for the entire tested line. At this time, the same distributed capacitance coupling current... It still exists, but because its return path impedance is extremely low (mainly determined by the current sensing resistor R2), according to Ohm's law... The interference voltage generated by this current at the detection point Suppressed to the millivolt or even microvolt level, it is negligible compared to the effective signal. Therefore, external noise is effectively "short-circuited" and discharged, unable to interfere with the subsequent high-precision detection of the characteristic current pulse.

[0050] By comparison Figure 8 and Figure 9It can be seen that the noise of the current-mode detection method used in this embodiment is significantly reduced and the characteristics are stable, indicating that the current pulse can effectively avoid the influence of power frequency voltage coupling and various voltage-type electromagnetic noise commonly found on power lines. At the same time, the receiver provides DC bias through a unique circuit design, which can quickly discharge the residual coupling voltage on the line. This allows the detection waveform to remain clear and distortion-free even in complex power environments, effectively preventing false triggering and improving the accuracy of leakage current detection.

[0051] The positioning principle of this device is based on the Time Domain Reflectometry (TDR) method. The distance calculation formula is: Where L is the distance to the fault point, v is the speed at which the signal propagates in the cable, and Δt is the two-way time difference between the pulse's transmission from the transmitting end to its reflection and return from the fault point.

[0052] For a typical PVC-insulated low-voltage copper core cable, the signal propagation speed v is approximately 2 × 10⁻⁶. 8 m / s. This device uses an ADC with a sampling rate of 250MHz, and its system time resolution can reach 4ns. Substituting into the formula, the theoretical ranging resolution is: This indicates that, in theory, this embodiment can achieve a positioning accuracy better than 0.5 meters, a level of accuracy that can meet the precise positioning needs of short-distance, multi-branch complex routes such as homes and offices.

[0053] Example 2: The current-type leakage detection device in this embodiment is basically the same as that in Embodiment 1, the main difference being the number of signal acquisition cards 2.

[0054] This embodiment includes a mobile control terminal 1 and two or more signal acquisition cards 2. Each signal acquisition card 2 is connected to a different point on the power line through a signal interface. The mobile control terminal 1 communicates with all the signal acquisition cards 2 in a network.

[0055] In real-world home wiring, fault points may be located in complex multi-branch topologies. To address this and further improve the accuracy and reliability of fault location, this invention supports collaborative testing using two or more signal acquisition cards 2. The mobile control terminal 1 has intelligent grouping capabilities, automatically planning and executing multiple rounds of testing to synthesize all data and derive the optimal result.

[0056] Users can connect multiple signal acquisition cards 2 to different key test points in the line, such as different sockets or terminals, depending on the line branching situation. The system's positioning is still based on measuring the signal propagation delay between any two points. When there are multiple devices, the mobile control terminal will control each device to take turns as a pulse transmitting unit, while all other devices simultaneously act as pulse receiving units for synchronous sampling.

[0057] Taking three signal acquisition cards 2 (D1, D2, D3) as an example, this process includes three sub-tests: First test: D1 sends a current pulse, and D2 and D3 receive and record the waveform synchronously; Second test: D2 sends a current pulse, and D1 and D3 receive and record the waveform synchronously; Third test: D3 sends a current pulse, and D1 and D2 receive and record the waveform synchronously.

[0058] This mode can acquire the propagation characteristics and reflection waveforms of all devices at once, which is particularly useful for determining whether there are multiple impedance discontinuities in the line or for evaluating the topology of complex branch networks.

[0059] Example 3: like Figure 7 As shown, this embodiment provides a current-type leakage current detection method, which can be applied to the current-type leakage current detection device described in Embodiment 1, and includes the following steps: S1. The mobile control terminal 1 establishes a wireless communication connection with at least two signal acquisition cards 2; S2. Connect at least two signal acquisition cards 2 to different points on the power line, and configure one of the signal acquisition cards 2 as a pulse transmitting unit and the other signal acquisition card 2 as a pulse receiving unit through the mobile control terminal 1. S3. The mobile control terminal 1 sends a command to the pulse sending unit to control the pulse sending unit to inject a fast transient current pulse into the power line. S4. The mobile control terminal 1 synchronously sends instructions to the pulse receiving unit to control the pulse receiving unit to provide DC bias to ground for the power line and synchronously detect the current pulses flowing through it. S5. The mobile control terminal 1 calculates and determines the location of the leakage fault point based on the propagation delay of the current pulse from the pulse transmitting unit to the pulse receiving unit.

[0060] In step S3, the mobile control terminal 1 mainly controls the switch S1 of the control pulse sending unit to be turned off and controls its digital-to-analog converter 24 to output a specific voltage waveform. Through the negative feedback loop formed by the operational amplifier U1 and the transistor Q1, a current pulse proportional to the voltage waveform is generated. The current pulse is injected into the power line from the collector of the transistor Q1 through the current sensing resistor R2.

[0061] In step S4, the mobile control terminal 1 mainly controls the pulse receiving unit to close the switch S1, and at the same time controls its digital-to-analog converter 24 to output a low level to turn off the transistor Q1. The power line interface is clamped to a potential close to the power supply voltage through the current sensing resistor R2 and the switch S1 to provide DC bias. The current pulse flowing through the power line generates a voltage drop across the current sensing resistor R2, which is amplified by the current sensing amplifier U2, sampled by the analog-to-digital converter 23, and sent to the system-on-a-chip 21 for processing.

[0062] It should be stated that the above-described specific embodiments are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art should understand that various modifications, equivalent substitutions, and variations can be made to the present invention. However, such variations, as long as they do not depart from the spirit of the present invention, should be within the scope of protection of the present invention. Furthermore, some terminology used in this specification and claims is not limiting, but merely for ease of description.

Claims

1. A current-type leakage current detection device, characterized in that: It includes a mobile control terminal (1) and at least two signal acquisition cards (2), wherein the mobile control terminal (1) communicates with all the signal acquisition cards (2) in a network and coordinates their control; At least one of the signal acquisition cards (2) serves as a pulse transmission unit, which is connected to the power line through its signal interface and injects current pulses into the power line; At least one of the signal acquisition cards (2) serves as a pulse receiving unit. The pulse receiving unit is connected to the power line through its signal interface to provide a DC bias to ground for the power line and directly detect the current pulses flowing through it. The mobile control terminal (1) is used to collect the propagation delay of the current pulse from the pulse sending unit to the pulse receiving unit and to calculate the location of the leakage fault point.

2. The current-type leakage current detection device according to claim 1, characterized in that: The signal acquisition card (2) includes a system-on-a-chip (21), a wireless communication module (22), an analog-to-digital converter (23), a digital-to-analog converter (24), and a transmitting / receiving circuit (25). The system-on-a-chip (21) is connected to the wireless communication module (22), the analog-to-digital converter (23) and the digital-to-analog converter (24) respectively. The transmitting / receiving circuit (25) is connected between the output terminal of the digital-to-analog converter (24) and the input terminal of the analog-to-digital converter (23), and is provided with a signal interface for accessing the line.

3. The current-type leakage current detection device according to claim 2, characterized in that: The transmitting / receiving circuit (25) includes an operational amplifier U1, a transistor Q1, a current sensing resistor R1, a current sensing resistor R2, a switch S1, and a current sensing amplifier U2; The non-inverting input terminal of the operational amplifier U1 is connected to the output terminal of the digital-to-analog converter (24), and the output terminal of the operational amplifier U1 is connected to the base of the transistor Q1. The emitter of the transistor Q1 is connected to the first terminal of the current sensing resistor R1, the second terminal of the current sensing resistor R1 is grounded, and the inverting input terminal of the operational amplifier U1 is connected to the emitter of the transistor Q1 to form negative feedback for voltage-to-current conversion. The collector of transistor Q1, the inverting input of current-sensing amplifier U2, and one end of switch S1 are all connected to the first end of current-sensing resistor R2; the second end of current-sensing resistor R2 is connected to power line interface and non-inverting input of current-sensing amplifier U2; the output of current-sensing amplifier U2 is connected to the input of analog-to-digital converter (23). The other end of the switch S1 is connected to the power supply voltage.

4. The current-type leakage current detection device according to claim 3, characterized in that: The transmitting / receiving circuit (25) has two working modes: transmitting and receiving. The system-on-a-chip (21) switches between transmitting and receiving modes by controlling the on / off state of the switch S1 and the output of the digital-to-analog converter (24). When the transmitting / receiving circuit (25) switches to the transmitting mode, the switch S1 is turned off, and the system-on-a-chip (21) controls the digital-to-analog converter (24) to output a specific voltage waveform. Through the negative feedback loop formed by the operational amplifier U1 and the transistor Q1, the voltage signal is converted into a current pulse proportional to the voltage wave. The current pulse flows out from the collector of the transistor Q1 and is injected into the power line through the current sensing resistor R2. When the transmitting / receiving circuit (25) switches to receiving mode, the switch S1 is closed, the digital-to-analog converter (24) outputs a low level to turn off the transistor Q1, and the power line interface is clamped to a potential close to the power supply voltage through the current sensing resistor R2 and the switch S1 to provide DC bias; the current pulse flowing through the power line generates a voltage drop across the current sensing resistor R2, which is amplified by the current sensing amplifier U2 and output to the analog-to-digital converter (23).

5. The current-type leakage current detection device according to claim 1, characterized in that: The mobile control terminal (1) communicates and synchronizes commands with each of the signal acquisition cards (2) via a wireless local area network hotspot.

6. The current-type leakage current detection device according to claim 2, characterized in that: The wireless communication module (22) is one of WIFI, Zigbee or Bluetooth.

7. The current-type leakage current detection device according to claim 1, characterized in that: Both the mobile control terminal (1) and the signal acquisition card (2) are equipped with built-in batteries, which power them.

8. A current-type leakage current detection method based on the current-type leakage current detection device according to any one of claims 1-7, characterized in that, Includes the following steps: S1. The mobile control terminal (1) establishes a wireless communication connection with at least two signal acquisition cards (2); S2. Connect at least two of the signal acquisition cards (2) to different points on the power line, and configure one of the signal acquisition cards (2) as a pulse sending unit and the other signal acquisition card (2) as a pulse receiving unit through the mobile control terminal (1); S3, the mobile control terminal (1) controls the pulse sending unit to inject current pulses into the power line; S4. The mobile control terminal (1) controls the pulse receiving unit to provide a DC bias to ground for the power line and simultaneously detects the current pulses flowing through it. S5. The mobile control terminal (1) calculates and determines the location of the leakage fault point based on the propagation delay of the current pulse from the pulse sending unit to the pulse receiving unit.

9. The current-type leakage current detection method according to claim 8, characterized in that, Step S3 specifically includes: The mobile control terminal (1) controls the switch S1 of the pulse sending unit to open and controls its digital-to-analog converter (24) to output a specific voltage waveform. Through the negative feedback loop formed by the operational amplifier U1 and the transistor Q1, a current pulse proportional to the voltage waveform is generated. The current pulse is injected into the power line from the collector of the transistor Q1 through the current sensing resistor R2.

10. The current-type leakage current detection method according to claim 8, characterized in that, Step S4 specifically includes: The mobile control terminal (1) controls the switch S1 of the pulse receiving unit to close, and at the same time controls its digital-to-analog converter (24) to output a low level to turn off the transistor Q1. The power line interface is clamped to a potential close to the power supply voltage through the current sensing resistor R2 and the switch S1 to provide DC bias. The current pulse flowing through the power line generates a voltage drop on the current sensing resistor R2. After being amplified by the current sensing amplifier U2, it is sampled by the analog-to-digital converter (23) and sent to the system-on-a-chip (21) for processing.

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