Cable joint fault on-line monitoring device

Abstract

The utility model discloses a cable joint fault on-line monitoring device which comprises an A-phase temperature measurement sensor, a B-phase temperature measurement sensor, a C-phase temperature measurement sensor, an A-phase ultrasonic partial discharge measurement sensor, a B-phase ultrasonic partial discharge measurement sensor, a C-phase ultrasonic partial discharge measurement sensor, a microprocessor module, a CT energy taking module and a wireless sending module. The device can monitor the temperature of the cable joint and the ultrasonic partial discharge condition in real time, and improves the accuracy of fault pre-judgment.

Description

TECHNICAL FIELD

[0001] The utility model relates to power equipment monitoring technical field, concretely is a cable joint fault on -line monitoring device. BACKGROUND

[0002] The output cable of ring network inflation switch cabinet is generally connected by cable accessories such as insulating sleeve and elbow plug. According to the analysis of the authoritative data of electric power industry, 90% of the faults in the full insulation switch cabinet occur in the cable connection of incoming and outgoing lines, which destroys the insulation capacity and leads to single-phase grounding fault or phase-to-phase short circuit accident. Cable stub head burning accident occurs frequently, which brings serious threat to power supply. At present, the temperature rise fault caused by poor cable joint connection is mainly reflected by measuring the surface temperature of cable accessories, but this method has limitations and cannot comprehensively monitor the fault condition of cable joint. CONTENT OF UTILITY MODEL

[0003] In order to overcome the deficiency of prior art, the utility model provides a cable joint fault on -line monitoring device, which can monitor the temperature and ultrasonic partial discharge of cable joint in real time and improve the accuracy of fault prediction.

[0004] A cable joint fault on -line monitoring device, including A phase temperature measurement sensor, B phase temperature measurement sensor, C phase temperature measurement sensor, A phase ultrasonic partial discharge measurement sensor, B phase ultrasonic partial discharge measurement sensor, C phase ultrasonic partial discharge measurement sensor, microprocessor module, CT energy taking module and wireless sending module.

[0005] A phase temperature measurement sensor, B phase temperature measurement sensor, C phase temperature measurement sensor, the output end of each phase temperature measurement sensor is connected with the input end I / O port of microprocessor module respectively;

[0006] A phase ultrasonic partial discharge measurement sensor, B phase ultrasonic partial discharge measurement sensor, C phase ultrasonic partial discharge measurement sensor, the output end of each phase ultrasonic partial discharge measurement sensor is connected with the input end A / D port of microprocessor module respectively;

[0007] CT energy taking module, its output end is connected with the power end of microprocessor module correspondingly and is used to provide working electric energy for the whole device;

[0008] Wireless sending module, its input end is connected with the communication interface of microprocessor module output end correspondingly and is used for uploading monitoring data to internet of things cloud platform.

[0009] The temperature measurement sensor of each phase adopts a negative temperature coefficient (NTC) thermistor, and a NE555 timer is combined to form a multi-resonance oscillation circuit. The NE555 chip converts the NTC resistance value corresponding to different temperature values into a digital frequency signal at the OUT pin, thereby improving the accuracy of the cable joint temperature measurement in a strong electric field and a strong magnetic field environment.

[0010] The ultrasonic partial discharge measurement sensor of each phase adopts an XR03RMH type ultrasonic sensor, which has a resonant frequency of 30 kHz, a diameter of 20 mm, and a height of 20 mm. The ultrasonic sensor can monitor the internal partial discharge of the cable joint in real time, and provide an important basis for fault prediction.

[0011] The microprocessor module adopts an STM32F407VGT6 as a microprocessor. This chip supports floating point operation (FPU) and DSP instructions, and can meet the requirements of the temperature measurement sensor and the ultrasonic partial discharge measurement sensor for FFT processing of collected temperature and ultrasonic data. The microprocessor module is responsible for receiving and processing data from various sensors, and performing fault analysis and prediction.

[0012] The CT power taking module includes an open type power taking CT, which is installed on the cable in the cable chamber. After the power taking CT obtains the power of the cable, it outputs an alternating induced voltage at the secondary side. Through rectification, voltage stabilization, filtering and other circuit processing, the alternating voltage is converted into a direct current voltage meeting the working requirements, thereby providing working power for the entire device.

[0013] The wireless sending module adopts a USR-G780 V2 type 4G DTU communication module, which supports 4G full network access, and can realize bidirectional data transmission through RS232 / 485 to 4G. The monitoring data is uploaded to the Internet of Things cloud platform through the wireless sending module, thereby realizing remote monitoring and data management.

[0014] The cable joint fault online monitoring device has the following advantages:

[0015] 1. The temperature and ultrasonic partial discharge of the cable joint can be monitored in real time, thereby improving the accuracy of fault prediction.

[0016] 2. The multi-resonance oscillation circuit composed of the NTC thermistor and the NE555 timer improves the accuracy of temperature measurement in a strong electric field and a strong magnetic field environment.

[0017] 3. The STM32F407VGT6 microprocessor is adopted, which supports floating point operation and DSP instructions, and meets the data processing requirements.

[0018] 4. The CT power taking module is adopted, thereby realizing self-power supply without the need of external power supply.

[0019] Adopt 4G DTU communication module, realize remote monitoring and data management, convenient operation and maintenance personnel grasp equipment state at any time BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the structural schematic diagram of cable joint fault on-line monitoring device of the utility model;

[0021] Figure 2 It is the circuit diagram of temperature measurement sensor;

[0022] Figure 3 It is the internal structure diagram of NE555 timer;

[0023] Figure 4 It is the schematic diagram of ultrasonic partial discharge measurement sensor;

[0024] Figure 5 It is the circuit diagram of CT energy taking module;

[0025] Figure 6 It is the schematic diagram of wireless sending module. DETAILED DESCRIPTION

[0026] The utility model will be further described below in conjunction with the drawings. The following examples are only used to more clearly illustrate the technical scheme of the utility model, and can not limit the protection scope of the utility model by this.

[0027] Example:

[0028] The embodiment provides a kind of cable joint fault on-line monitoring device, its structure as shown in Figure 1 The device includes A phase temperature measurement sensor, B phase temperature measurement sensor, C phase temperature measurement sensor, A phase ultrasonic partial discharge measurement sensor, B phase ultrasonic partial discharge measurement sensor, C phase ultrasonic partial discharge measurement sensor, microprocessor module, CT energy taking module and wireless sending module.

[0029] A phase temperature measurement sensor, B phase temperature measurement sensor, C phase temperature measurement sensor, the output end of each phase temperature measurement sensor is connected with the input end I / O port of microprocessor module respectively;

[0030] A phase ultrasonic partial discharge measurement sensor, B phase ultrasonic partial discharge measurement sensor, C phase ultrasonic partial discharge measurement sensor, the output end of each phase ultrasonic partial discharge measurement sensor is connected with the input end A / D port of microprocessor module respectively;

[0031] CT energy taking module, its output end is connected with the power supply end of microprocessor module corresponding, for providing working electric energy for entire device;

[0032] A wireless sending module, an input end of which is connected with a communication interface corresponding to an output end of the microprocessor module, is used for uploading the monitoring data to the Internet of Things cloud platform.

[0033] The temperature measurement sensor adopts a negative temperature coefficient (NTC) thermistor, and a NE555 timer is combined to form a multi-resonance oscillation circuit. The NE555 chip converts the NTC resistance value corresponding to different temperature values into a digital frequency signal at the OUT pin, thereby improving the accuracy of the cable joint temperature measurement in a strong electric field and a strong magnetic field environment. The temperature measurement sensor is as shown in Figure 2 .

[0034] As shown in Figure 3 , the NE555 internal structure is composed of comparators C1 and C2, an RS flip-flop, and a discharge tube. If the voltage on the capacitor C21 in the circuit is U c , the following table shows the relationship at the OUT pin of the NE555 timer:

[0035] Table 1: Internal state relationship of NE555 timer

[0036]

[0037] As can be seen from Table 1, after the temperature and sound measurement sensor is powered on, the 5V power supply charges the capacitor C21 through resistors R24 and R10. When U c < 5 / 3V, the states of C1 and C2 are 1 and 0, Q is 1, the discharge tube is cut off, and the OUT outputs a high level; when 5 / 3V < U c < 10 / 3V, the states of C1 and C2 are 1 and 1, Q remains the previous state of 1, the discharge tube remains cut off, and the OUT pin is at a high level; when U c > 10 / 3V, the states of C1 and C2 are 0 and 1, Q is 0, the discharge tube is turned on, and the OUT is at a low level. At this time, the capacitor C21 is discharged and the voltage drops. When U c drops between 5 / 3V and 10 / 3V, the states of C1 and C2 are 1 and 1, Q remains at 0, and the OUT is still at a low level; when U c continues to drop below 5 / 3V, C21 starts to charge again. The oscillation circuit causes the OUT pin of the NE555 to output a rectangular pulse through the repetitive charging and discharging process of the capacitor C21. The amplitude of the pulse signal is amplified through the transistor and the pull-up resistor. The rectangular pulse signal is captured by the microprocessor to measure the temperature of the cable joint.

[0038] The ultrasonic partial discharge measurement sensor of each phase adopts an XR03RMH ultrasonic sensor to monitor the partial discharge inside the cable joint in real time. The resonant frequency of the sensor is 30 kHz, the diameter is 20 mm, and the height is 20 mm. The ultrasonic sensor converts the collected ultrasonic signals into electrical signals and outputs them to the microprocessor module for processing.

[0039] As shown in Figure 4 , the microprocessor module adopts STM32F407VGT6 as the microprocessor to perform FFT processing on the collected temperature and ultrasonic data to extract fault feature information. The microprocessor module is also responsible for controlling the workflow of the entire device and uploading the monitoring data to the Internet of Things cloud platform through the wireless sending module.

[0040] The open-type power taking CT provides working power. The power taking CT is installed on the cable in the cable chamber. After the power taking CT obtains the power of the cable, it outputs an alternating induced voltage on the secondary side. The output voltage does not meet the working voltage requirement of the ultrasonic measurement sensor. To convert the alternating voltage output by the power taking CT on the secondary side into a direct current voltage that meets the working requirement, the CT power taking module circuit is as shown in Figure 5 .

[0041] As shown in Figure 5 , the circuit converts the voltage output by the power taking CT on the secondary side into a direct current voltage through the rectifier bridge D1. The direct current charges the super-capacity electrolytic capacitor C10 and the tantalum capacitor C11 after passing through the resistor R4; when the voltage on C10 and C11 increases to the reverse breakdown threshold of the stabilizing tube D3, D3 is immediately turned on, thereby causing C10 and C11 to charge the tantalum capacitor C12. Once the voltage on C12 reaches the gate voltage of the voltage monitoring chip S80848, S80848 will charge the parasitic capacitor of the MOS tube Q1 through its OUT pin and the diode D4 and the current-limiting resistor R6 when it is running. Once the gate voltage of the MOS tube reaches the threshold of 3V, the MOS tube is turned on to provide power for the STM32F407VGT6 microprocessor of the ultrasonic measurement sensor. After the STM32 is powered on and runs, it will control the I / O port to make control high, and charge Q1 through diode D5 and R6. In this process, diodes D4 and D5 form an OR gate in logic. The goal of this design is that when the STM32 chip is powered on and runs, the release of the front-end energy will cause the voltage on C12 to decrease. Once this voltage decreases below the gate voltage of S80848, S80848 will stop running, causing the MOS to be cut off, thereby affecting the provision of working power for the ultrasonic measurement sensor. However, through the design in this paper, when S80848 stops running, D5 can still forcibly turn on the MOS tube, ensuring the stability of the power supply.

[0042] Meanwhile, when a short-time fault occurs in the three-phase cable, the large current generated by the fault can be reduced by the resistance R4, the high-voltage capacitors C8 and C9, and the bidirectional TVS transient voltage suppression tube D2, so as to protect and charge the current limiting function of the thermoacoustic measurement sensor. The use of the resistance R5 can forcibly pull down the level, prevent the impedance mismatch of the circuit itself when charging, and affect the MOS to turn on in advance, which affects the collection of electric energy; the use of the resistances R7 and R8 in series can divide the voltage, when the voltage of C12 to ground collected by the microprocessor ADC pin is lower than 5V, through the control of the level of control, R5 is pulled down, S80848 and MOS are cut off, and STM32 stops working, so as to continue the collection of electric energy; at the same time, due to the cut-off of the MOS, the subsequent circuit is powered off, there is no power consumption of the power device, and the low-power energy efficiency of the thermoacoustic measurement sensor is improved.

[0043] The wireless sending module adopts a USR-G780 V2 type 4G DTU communication module to upload the monitoring data to an Internet of Things cloud platform. The DTU of this type supports 4G full network, can realize bidirectional data transmission through RS232 / 485 to 4G, the cloud platform provided by the module can realize remote monitoring of device data, realizes webpage monitoring large screen, and can remotely configure the parameters of the DTU, obtain the position of the DTU and remotely upgrade the DTU, and at the same time, based on the cloud platform technology, data communication between the online monitoring device and the background management system can be realized. The USR-G780 V2 type DTU is as shown in Figure 6

[0044] Through the cable joint fault online monitoring device, the temperature and ultrasonic partial discharge of the cable joint can be monitored in real time, the accuracy of fault prediction is improved, and powerful guarantee is provided for the safe operation of the power equipment.

[0045] The above only describes preferred embodiments of the present application, and it should be pointed out that, for ordinary skilled persons in the technical field, without departing from the technical principles of the present application, a number of improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection range of the present application.​

Claims

1. A cable joint fault on-line monitoring device, characterized by, The temperature measuring sensor of phase A, the temperature measuring sensor of phase B, the temperature measuring sensor of phase C, the ultrasonic partial discharge measuring sensor of phase A, the ultrasonic partial discharge measuring sensor of phase B, the ultrasonic partial discharge measuring sensor of phase C, a microprocessor module, a CT power taking module, and a wireless sending module are included. The output ends of the temperature measuring sensor of phase A, the temperature measuring sensor of phase B, and the temperature measuring sensor of phase C are connected with the input ends I / O of the microprocessor module respectively. The output ends of the ultrasonic partial discharge measuring sensor of phase A, the ultrasonic partial discharge measuring sensor of phase B, and the ultrasonic partial discharge measuring sensor of phase C are connected with the input ends A / D of the microprocessor module respectively. The CT power taking module is connected with the corresponding power supply end of the microprocessor module, and is used for providing working power for the whole device. The input end of the wireless sending module is connected with the corresponding communication interface of the output end of the microprocessor module, and is used for uploading the monitoring data to the Internet of Things cloud platform.

2. The cable joint fault online monitoring device according to claim 1, characterized in that, The temperature measuring sensor adopts a negative temperature coefficient thermistor, and a multi-resonance circuit is formed by combining a NE555 timer, so as to convert the NTC resistance value corresponding to different temperature values into a digital frequency signal, so as to improve the accuracy of cable joint temperature measurement in a strong electric field and a strong magnetic field environment.

3. The cable joint fault online monitoring device according to claim 1, characterized in that, The ultrasonic partial discharge measuring sensor is an XR03RMH ultrasonic sensor, and the resonant frequency thereof is 30 kHz.

4. The cable joint fault online monitoring device according to claim 1, characterized in that, The microprocessor module adopts STM32F407VGT6 as a microprocessor, supports floating point operation and DSP instruction, and is used for performing FFT processing on the collected temperature and ultrasonic data.

5. The cable joint fault online monitoring apparatus according to claim 1, characterized by, The CT power taking module includes an open type power taking CT, which is installed on a cable in a cable room, is used for obtaining the power of the cable, and converts the alternating voltage output by the secondary side of the power taking CT into a direct current voltage meeting the working requirements through rectification, voltage stabilization, filtering and other circuit processing.

6. The cable joint fault online monitoring apparatus according to claim 1, characterized by, The wireless sending module adopts a USR-G780 V2 type 4G DTU communication module, supports 4G full network, and can realize bidirectional data transmission by converting RS232 / 485 to 4G, so as to upload the monitoring data to the Internet of Things cloud platform.

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