A live detection device for high-voltage cable sheath

Abstract

This utility model relates to the field of power cable testing technology, specifically a live-line testing device for high-voltage cable sheaths. It includes a DSP core processor with a main frequency of no less than 150MHz, used for functional control of the testing device and information interaction with the control equipment; and a frequency-injection and output module, comprising a frequency-injection signal generator, a power amplifier, and a relay switching circuit, which can inject frequency-injection excitation signals into the cable sheath through coupling clamps. This utility model achieves non-contact live-line testing of the insulation performance of high-voltage cable sheaths, enabling assessment of sheath status under uninterrupted power supply or low-risk conditions. It solves the problem of messy wiring during path transmission, improves operational convenience, and increases device testing efficiency. It is easy to operate and has high measurement efficiency.

Description

Technical Field

[0001] This utility model relates to the field of power cable testing technology, and more specifically, to a device for detecting live sheath of high-voltage cables. Background Technology

[0002] With the acceleration of urbanization, underground cables are gradually replacing overhead lines and becoming the main power transmission method for urban power grids. High-voltage cables (such as 110kV, 220kV and above) are widely used in urban power grids, cross-sea power transmission, and new energy grid connection due to their advantages such as large transmission capacity, small footprint, and environmental friendliness.

[0003] High-voltage cables typically consist of a conductor, a main insulation layer, a metallic sheath (aluminum or lead), and an outer sheath. The metallic sheath is a crucial component, protecting the insulation from moisture, mechanical damage, and the effects of light and chemical corrosive media. It also serves as a path for short-circuit current. The metallic sheath needs to be grounded to shield against the electric field. However, damage or failure of the sheath insulation (outer sheath or cross-connection system) can lead to multiple grounding points in the metallic sheath, creating circulating currents, increasing commutation losses, increasing induced current in the metallic sheath, causing heat generation and energy loss, and even cable burnout. Therefore, the operating condition of the sheath directly affects the overall operational safety and expected lifespan of the cable. Initially, sheath defects may not show obvious symptoms, but long-term accumulation can lead to sudden failures that are difficult to detect through traditional inspections. Visual inspection can only detect surface damage and cannot assess the internal insulation condition.

[0004] Existing testing methods often require power outages, impacting power supply reliability. While live-line testing technologies exist, they generally suffer from bulky equipment, complex operation, and insufficient accuracy. Therefore, there is an urgent need for a live-line testing method that can quantitatively reflect the operational status of the cable sheath circuit, thereby monitoring and evaluating the health of the sheath circuit and improving cable maintenance and testing efficiency. There is a pressing need to develop a portable, non-contact live-line testing device for high-voltage cable sheaths to assess sheath condition without power outages or under low-risk conditions. Utility Model Content

[0005] This invention provides a high-voltage cable sheath live detection device, which solves the technical problems in the prior art.

[0006] In view of the above problems, the technical solution proposed by this utility model is as follows:

[0007] A live-line detection device for high-voltage cable sheaths, comprising:

[0008] The DSP core processor, with a main frequency of not less than 150MHz, is used for the functional control of the detection device and the information interaction with the control equipment.

[0009] The heterogeneous frequency signal generation and output module includes a heterogeneous frequency signal generator, a power amplifier and a relay switching circuit, which can inject heterogeneous frequency excitation signals into the cable sheath through a coupling clamp;

[0010] The heterogeneous frequency sampling and conversion module includes a current transformer, a current-to-voltage conversion circuit, and an analog-to-digital converter. It can sense the response current signal in the sheath circuit through the current transformer, and input it to the analog-to-digital converter through the current-to-voltage conversion circuit to generate a digital signal. The generated digital signal is then sent to the DSP core processor system.

[0011] The power conversion module is powered by a lithium battery and generates multi-stage voltages through isolated DC-DC conversion.

[0012] The wireless communication module communicates with the host computer via WiFi to exchange commands and transmit data.

[0013] Furthermore, the wireless communication module supports point-to-point WiFi connection with a data update cycle of ≤100μs.

[0014] Furthermore, the testing device is also equipped with a 30MHz crystal oscillator, an external JTAG programming module, an SPI Flash memory, and an SRAM internal storage chip. The 30MHz crystal oscillator provides the working pulse for the processor; the external JTAG programming module downloads programs to the board and performs online debugging; the SPI Flash memory stores data for the DSP core processor; and the SRAM internal storage chip provides sufficient memory space for the DSP core processor during data processing.

[0015] Furthermore, the current range of the inter-frequency sampling conversion module is ±500mA, and a non-contact current transformer is used to connect the cable.

[0016] Furthermore, the detection device also includes a multi-channel control module that switches the excitation and acquisition channels of the A / B / C three-phase cables via relays.

[0017] Furthermore, the detection device also includes an environmental monitoring module, which monitors the working environment in real time by integrating temperature and humidity sensors.

[0018] Furthermore, the detection device also includes an LCD screen that displays battery level, temperature and humidity, signal strength, and operating mode in real time.

[0019] Compared with existing technologies, the advantages of this invention are as follows: This device uses an injection signal with a different frequency than the cable's operating voltage for excitation output. It employs a non-contact, isolated injection method to inject this signal into the working cable. During measurement, mutual inductance is used to detect the injected signal into the cable sheath, thus achieving non-contact live-line detection of the insulation performance of high-voltage cable sheaths. This allows for assessment of sheath condition under uninterrupted power supply or low-risk conditions. Wireless WIFI connection enables data transmission with the backend system, solving the problem of messy wiring during transmission, improving operational convenience, and increasing device detection efficiency. A multi-channel control module automatically switches between signal injection and signal acquisition for each phase of the cable. Operation is simple and measurement efficiency is high. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a structural block diagram of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] Please see Figure 1 A live-line detection device for high-voltage cable sheaths includes a DSP core processor, a power conversion module, a frequency signal generation and output module, a frequency sampling and conversion module, a wireless communication module, an environmental monitoring module, and an LCD screen.

[0025] The DSP core processor uses the TI TMS320C2000™ series digital signal control chip, which has the advantages of high precision, low overhead, strong computing power, accurate AC / DC conversion and short time. Its CPU main frequency can reach up to 150MHz, improving performance by nearly 50%. It can realize the parsing of the wireless WIFI communication transmission and reception protocol with the control device, receive and parse the "control" commands issued by the upper-level system, and then allocate and execute commands to the detection device. It also uploads the monitoring status and acquisition results of the detection device to the upper-level system via WIFI, thus completing the functional control of the detection device and the information interaction with the control device to complete the detection task.

[0026] Furthermore, the control board is equipped with a 30MHz crystal oscillator to provide operating pulses for the processor; the external JTAG programming module connects to an external chip programmer via a JTAG interface on the board, connected by a 14-pin ribbon cable. After connection, the board can be programmed via computer, and online debugging can be performed when necessary; the board processor is equipped with an SPI Flash memory for storing data for the DSP core processor; in addition, an internal SRAM memory chip is configured to provide sufficient memory space for the DSP core processor during data processing.

[0027] The power conversion module circuit can generate different power voltages required by each module circuit from the power entering the board. The board is powered by a lithium battery pack, with an external built-in battery pack connected at the power input. The battery specifications are 24V / 6000mAh. After the power enters the board, it is filtered by a common-mode inductor and capacitor, and a diode is connected in series to protect the board from reverse connection. The power entering the board is then converted into different power voltages such as +12V, -12V, 5V, 3.3V, and 1.8V by an isolated DC-DC converter module.

[0028] Furthermore, the power conversion module adopts a combination of DC-DC conversion and LDO conversion to meet the power supply voltage requirements of each circuit on the board. At the power input, an isolated DC-DC module is used to perform an overall power conversion and isolation, and then the voltage is distributed to each circuit through a transformer. A DC-DC conversion chip is used to provide 3.3V power, which is highly efficient and has low loss. An LDO is used to provide the core voltage for the processor core, which has low voltage ripple and good performance.

[0029] The heterogeneous frequency signal generation and output module includes a heterogeneous frequency signal generator and a power amplifier. In actual operation, the heterogeneous frequency signal generator uses a DAC chip to generate a sinusoidal excitation waveform that is different from the cable's operating frequency. After being amplified by the power amplifier, it is output to the excitation coil and then injected into the cable sheath through the coupling clamp.

[0030] Because a non-contact isolation method is used to provide a sinusoidal excitation voltage to the coupling injection coil, it ensures that the different frequency signal can be effectively loaded into the cable sheath grounding circuit to generate the corresponding different frequency response signal. Since the detection is performed using a sinusoidal signal, only the single frequency sinusoidal signal component needs to be processed. The corresponding high-order harmonic interference is small, the effective utilization rate of the signal is high, the signal separation and filtering are relatively easy, and the signal-to-noise ratio of the detection process can be easily improved.

[0031] The frequency sampling conversion module includes a current transformer, a current-to-voltage conversion circuit, and an analog-to-digital converter. The interface is connected to the main circuit cable via the current transformer to collect analog signals in an inductive manner. After the AC analog current signal (input range of + / -500mA) enters the board, it is first converted and conditioned into a digital signal by the current-to-voltage conversion circuit, and then the voltage signal is converted into a digital signal by the analog-to-digital converter and sent to the processor for processing.

[0032] Furthermore, the detection device has three excitation output interfaces, which are respectively clamped onto the A, B, and C phases of the high-voltage cable via coupling clamps. The detection device is equipped with a multi-channel control module, which switches the interface for injecting or acquiring different frequency signals through a relay switching circuit. It can inject different frequency signals into the A, B, and C phases of the high-voltage cable, or acquire the current signals of the A, B, and C phases of the high-voltage cable.

[0033] The wireless communication module is the interface for communication and data exchange with the system control equipment. It connects to and controls the detection equipment via WIFI, enabling information transmission and interaction between systems. The communication data update cycle is 100us, allowing for real-time updates, making it simple, convenient, and efficient to operate.

[0034] The environmental monitoring module can collect ambient temperature and humidity signals during device use through the set temperature and humidity sensors, thereby enabling real-time monitoring of the temperature and humidity information of the circuit board environment during operation.

[0035] The LCD screen displays the real-time operating status of the testing device, allowing users to directly observe key information such as battery level, ambient temperature and humidity, wireless connection status, operating mode, test status, and signal strength, making it convenient for users to operate.

[0036] During operation, the device first connects the coupling clamp to the cable sheath and the current transformer to the grounding wire. A command is sent from the mobile terminal to the DSP core processor. The excitation output circuit then couples an AC excitation signal of a different frequency into the loop formed between the two grounded bodies under test. The response voltage / current is collected by the different frequency sampling and conversion circuit. The DSP core processor uses Ohm's law (R=U / I) to calculate the ground contact resistance of the high-voltage cable sheath, thereby determining whether the high-voltage cable is properly grounded. Finally, the detection data is uploaded to the mobile terminal via WiFi, and the results are displayed in real time on the LCD screen. Because this device uses a method similar to that used in cable engineering, the excitation output is optimized for cable operation. This device injects voltage-frequency signals into the working cable using a non-contact, isolated injection method. During measurement, the injected signals are detected in the cable sheath via mutual inductance, enabling non-contact live-line testing of the high-voltage cable sheath insulation performance. This allows for sheath condition assessment under uninterrupted power supply or low-risk conditions. Wireless Wi-Fi connectivity facilitates data transmission with the backend system, eliminating messy wiring issues and improving operational convenience and device efficiency. A multi-channel control module automatically switches between signal injection and acquisition for each phase of the cable. Operation is simple and measurement efficiency is high.

[0037] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A high voltage cable shield belt live detection device, characterized in that, include: The DSP core processor, with a main frequency of not less than 150MHz, is used for the functional control of the detection device and the information interaction with the control equipment. The heterogeneous frequency signal generation and output module includes a heterogeneous frequency signal generator and a power amplifier, which injects heterogeneous frequency excitation signals into the cable sheath through coupling clamps; The heterogeneous frequency sampling and conversion module includes a current transformer, a current-to-voltage conversion circuit, and an analog-to-digital converter. It can sense the response current signal in the sheath circuit through the current transformer, and input it to the analog-to-digital converter through the current-to-voltage conversion circuit to generate a digital signal. The generated digital signal is then sent to the DSP core processor system. The power conversion module is powered by a lithium battery and generates multi-stage voltages through isolated DC-DC conversion. The wireless communication module communicates with the host computer via WiFi to exchange commands and transmit data.

2. The high-voltage cable sheath live-line detection device according to claim 1, characterized in that, The wireless communication module supports point-to-point WiFi connection with a data update cycle of ≤100μs.

3. The high voltage cable shield tape electrical detection apparatus of claim 1, wherein, The testing device is also equipped with a 30MHz crystal oscillator, an external JTAG programming module, an SPI Flash memory, and an SRAM internal storage chip. The 30MHz crystal oscillator provides the working pulse for the processor; the external JTAG programming module downloads programs to the board and performs online debugging; the SPI Flash memory stores data for the DSP core processor; and the SRAM internal storage chip provides sufficient memory space for the DSP core processor during data processing.

4. The high voltage cable shield tape electrical detection apparatus of claim 1, wherein, The current range of the frequency sampling conversion module is ±500mA, and it uses a non-contact current transformer clamp cable.

5. The high voltage cable shield tape electrical detection apparatus of claim 1, wherein, The detection device also includes a multi-channel control module that switches the excitation and acquisition channels of the A / B / C three-phase cable via relays.

6. The high voltage cable shield tape electrical detection apparatus of claim 1, wherein, The testing device also includes an environmental monitoring module, which monitors the working environment in real time through integrated temperature and humidity sensors.

7. The high voltage cable shield tape electrical detection apparatus of claim 1, wherein, The testing device also includes an LCD screen that displays real-time battery level, temperature and humidity, signal strength, and operating mode.

Images