CN203561449U - A buried cable intermediate connector temperature online monitoring system - Google Patents

Abstract

The utility model relates to an on-line temperature monitoring system for power cables, in particular to an on-line temperature monitoring system for an intermediate joint of buried cables. The monitoring system consists of a wireless sensor node, a thermoelectric generator (TEG) and a wireless temperature measurement concentrator. The middle joint of the buried cable is located under the cable well, and the wireless sensor node and the thermoelectric generator are installed on the outer surface of the middle joint of the cable; the wireless The temperature measuring concentrator is installed in the switching station, ring network cabinet or cable branch box at the cable terminal or branch joint, and its antenna is extended to the cable channel to collect the monitoring data of wireless sensor nodes. The utility model adopts thermoelectric generator and energy The collector converts the temperature difference into electrical energy to supply power to the wireless sensor, and at the same time collects monitoring data wirelessly; the wireless sensor nodes work in a low-power mode, thereby reducing the power consumption of the entire monitoring system.

Description

An online monitoring system for the temperature of the intermediate joint of buried cables

technical field

The utility model relates to an on-line temperature monitoring system for electric cables, in particular to an on-line temperature monitoring system for an intermediate joint of buried cables.

Background technique

With the urbanization and the development of urban power grids, power cables have been widely used, and the average annual growth rate in my country has reached 35%. With the increase in the number of cables used and the increase in power transmission capacity, once a fault occurs, the damage will be serious, so the operational reliability of power cables has received more and more attention. Through the investigation of the failure rate of power cables in major cities across the country, it is found that within 1 to 5 years of the initial operation of the cable and 5 to 25 years after being put into operation, the failure of power cable accessories (including branch joints, terminal joints and intermediate joints) rate is always the highest. In particular, the production process requirements of the cable intermediate joint are high, and there is a greater possibility of potential accidents, so online monitoring of its temperature is of great significance.

Existing on-line monitoring methods for cable temperature include point-type temperature measurement method and line-type temperature measurement method. 1) The traditional point-type temperature measurement method uses temperature sensors such as thermocouples, thermal resistors, and thermistors to measure the temperature of local points on the outer surface of the protective shell of the intermediate joint or the surface of the outer sheath of the cable body. The monitoring device generally uses batteries or electromagnetic induction to take power The device is powered. If a battery is used for power supply, it is easy to burst at high temperature, and the battery needs to be replaced regularly, resulting in a large maintenance workload. When the electromagnetic induction power taking device is used for power supply, if the current in the cable is small, the electric energy cannot be taken out, and the monitoring device stops working; if the cable current is large, the monitoring device is easy to burn out. When monitoring the three-core cable, the electromagnetic induction power-taking device cannot work. 2) The linear temperature measurement method generally uses temperature-sensing cables, distributed optical fiber temperature sensors, and optical fiber grating temperature sensors to be bound on the surface of the outer sheath of the cable (or embedded inside the cable) along the cable line to measure the temperature of the entire cable. This method is suitable for measuring the temperature trend of the entire cable and the thermal bottleneck area, but the cost of long-distance laying is high and the installation project is huge.

Utility model content

Aiming at the problems of the existing on-line monitoring system for cable intermediate joints such as high cost, difficulty in power supply, and difficulty in installation and maintenance, the purpose of this utility model is to provide an on-line monitoring system for the temperature of buried cable intermediate joints. The utility model uses a wireless sensor to measure the temperature of the cable The temperature of the outer skin of the intermediate joint transmits monitoring data wirelessly, and uses thermoelectric generators and energy harvesters to convert the temperature difference into electrical energy to power wireless sensors. It has the advantages of low cost, maintenance-free, convenient installation, and high safety.

The purpose of this utility model is to adopt following technical scheme to realize:

The utility model provides an on-line monitoring system for the temperature of an intermediate joint of buried cables. The system includes N wireless sensing nodes, a thermoelectric generator and a wireless temperature measuring concentrator arranged above the cable well. The improvement lies in: The cable intermediate joint is arranged under the cable well, and a single wireless sensor node and a thermoelectric generator are installed side by side on the outer surface of the cable intermediate joint in sequence; In the ring network cabinet or cable branch box, its antenna is extended to the cable channel to collect monitoring data of wireless sensor nodes.

Preferably, the high temperature side of the thermoelectric generator is pasted on the outer skin of the cable intermediate joint, and the low temperature side diffuses the heat flow into the air through the radiator; the distance between adjacent cable intermediate joints is 100 to 400 meters .

Preferably, the single wireless sensor node includes an energy harvester, a microcontroller, and a first wireless transceiver connected in sequence, and the semiconductor temperature sensor is connected to the microcontroller; the semiconductor temperature sensor and the first wireless transceiver are connected through the microcontroller's The VOUT pin gets power.

More preferably, the energy harvester includes an energy harvesting management chip, a microtransformer, a supercapacitor, and a capacitor; the microtransformer, supercapacitor, and capacitor are all connected to the energy harvesting management chip.

More preferably, the semiconductor temperature sensor adopts a TMP36 type sensor.

More preferably, the microcontroller internally integrates analog-to-digital converters, timers, general-purpose I/O, and interrupt controller on-chip peripherals;

The microcontroller is connected to the first wireless transceiver through the serial peripheral SPI interface, and uses the general I/O output shutdown or shutdown signal SDN to control the power-on reset and working power of the first wireless transceiver.

More preferably, a thermoelectric generator and an energy collector are used to convert the temperature difference between the intermediate joint of the cable and the environment into electrical energy to supply power to the wireless sensor nodes.

Preferably, the wireless temperature measurement concentrator is powered by the mains, PT power supply or battery in the switching station, ring network cabinet or cable branch box, including a microprocessor, a second wireless transceiver, a GPRS module/optical fiber Ethernet Interface, LCD display screen, radio frequency circuit and antenna; Described second wireless transceiver, GPRS module/optical fiber Ethernet interface and LCD display screen are connected with microprocessor respectively, and described antenna is connected with second wireless transceiver by radio frequency circuit .

Preferably, the frequency band of the wireless communication between the wireless sensor node and the wireless temperature measurement concentrator is 433MHz, the communication protocol is IEEE802.15.4g, and the authentication is performed through a key.

Compared with the prior art, the beneficial effects achieved by the utility model are:

1. In the on-line temperature monitoring system for the intermediate joints of buried cables provided by this utility model, its wireless sensor nodes are powered by thermoelectric generators TEG and energy harvesters, which avoids the huge workload of laying special power supply cables or regularly replacing batteries, and eliminates It eliminates the potential safety hazards and unreliability caused by the use of electromagnetic induction power supply devices for power supply, and has the advantages of maintenance-free, convenient installation, and low cost;

2. The wireless sensor node and the wireless temperature measuring concentrator in the utility model transmit data in a wireless manner, eliminating the need for additional communication cables, and at the same time, the system has a strong ability to resist electromagnetic interference;

3. The wireless sensor nodes in the utility model work with a very low duty cycle, and the data upload adopts a point-by-point collection method, thereby reducing the power consumption of the system;

4. The utility model utilizes energy collection technology to convert waste heat into electric energy required for the work of wireless sensor nodes, which plays the role of energy saving and environmental protection.

Description of drawings

Fig. 1 is the structural diagram of the buried cable intermediate joint temperature online monitoring system provided by the utility model;

Fig. 2 is a schematic diagram of the wireless sensor node structure provided by the utility model.

Detailed ways

Below in conjunction with accompanying drawing, the specific embodiment of the present utility model is described in further detail.

Aiming at the problems of high cost, difficult power supply, difficult installation and maintenance of the existing on-line monitoring system for intermediate joints of cables, the utility model adopts a thermoelectric generator and an energy collector to convert temperature difference into electric energy to supply power for wireless sensors, and at the same time collect and monitor in a wireless manner Data; wireless sensors work in a low-power mode, thereby reducing the power consumption of the entire monitoring system.

The structure diagram of the on-line monitoring system for the temperature of the buried cable intermediate joint provided by the utility model is shown in Figure 1. The on-line temperature monitoring system includes at least one wireless sensor node and a thermoelectric generator (TEG) arranged above the cable well. , wireless temperature measurement concentrator and background monitoring center (master station). Among them, the buried cable intermediate joint is located under the cable well, and the distance between adjacent joints is 100-400 meters; each wireless sensor node and thermoelectric generator are installed side by side on the outer surface of the cable intermediate joint; the wireless temperature measurement concentrator is installed on the In the switching station, ring network cabinet or cable branch box at the cable terminal or branch joint, its antenna is extended to the cable channel to collect the monitoring data of wireless sensor nodes, and send it to the background monitoring center through GPRS or optical fiber.

a) Thermoelectric Generator TEG:

The thermoelectric generator TEG can convert the temperature difference on both sides into a voltage by applying the Seebeck Effect, and the amplitude and polarity of the output voltage depend on the amplitude and polarity of the temperature difference. The high temperature side of the thermoelectric generator is pasted on the outer skin of the cable intermediate joint, and the low temperature side diffuses the heat flow into the air through the radiator to ensure the temperature difference between the two sides of the thermoelectric generator.

2) Wireless sensor node: It consists of an energy harvester, a microcontroller, a first wireless transceiver and a semiconductor temperature sensor. Connector connection, the schematic diagram of its structure is shown in Figure 2.

<1> The energy harvester mainly includes the energy harvesting management chip LTC3108, microtransformer T1 (model: LPR6235-752SMLB), supercapacitor and other capacitors. The energy harvester can convert the voltage (20mV ~ 500mV) output by the TEG to the working voltage (2.2V, 3.3V) of the microcontroller, the first wireless transceiver and the semiconductor temperature sensor. When the output voltage VOUT reaches the preset value At 93%, a valid PGOOD signal is output to the microcontroller, and the supercapacitor is charged to 5.25V at the same time. When the voltage output by the TEG is lower than 20mV, the supercapacitor starts to discharge and supplies power to the microcontroller, the first wireless transceiver and the semiconductor temperature sensor through the LTC3108.

<2>The semiconductor temperature sensor TMP36 converts the temperature signal into an analog voltage signal and outputs it to the microcontroller. When it works in normal mode, the working current is less than 50μA; when it is in off mode, the working current is less than 0.5μA.

<3> The microcontroller is the control center of the entire wireless sensor node, which integrates on-chip peripherals such as ADC, timer, general-purpose I/O, and interrupt controller. The microcontroller is connected to the first wireless transceiver SI4463 through the SPI interface, and uses the general I/O to output the SDN signal to control the power-on reset and working power of the first wireless transceiver. The microcontroller starts the ADC regularly to convert the temperature analog signal into a digital signal, and sends the monitoring data through the first wireless transceiver. When the A/D conversion is not performed, the microcontroller will set the #SHDN signal output to the temperature sensor low to reduce the power consumption of the temperature sensor, and at the same time disable the sending function of the first wireless transceiver. For data reception, a listening mode is used to reduce the average current consumed by the wireless transceiver. Sleep mode is entered when the microcontroller is not in use, reducing its operating current to 1µA and allowing a timer interrupt to wake up the device. Because the microcontroller and the first wireless transceiver work at a relatively low duty cycle, their average power consumption is very low, about a few milliwatts.

3) Wireless temperature measurement concentrator: powered by mains power, PT power supply or battery in the switching station/ring network cabinet/cable branch box, including microprocessor, second wireless transceiver, GPRS module/optical fiber Ethernet interface, LCD displays, radio frequency (RF) circuits, antennas, etc. Wherein, the wireless transceiver, GPRS module/optical fiber Ethernet interface and LCD display are respectively connected with the microprocessor, and the antenna is connected with the second wireless transceiver through a radio frequency (RF) circuit.

The functions of the wireless temperature measurement concentrator include: collecting temperature data uploaded by wireless sensor nodes in the cable channel, local display and alarm of temperature data, configuring parameters of wireless sensor nodes, receiving and executing commands from the monitoring center, uploading monitoring data, etc.

In the monitoring system provided by the utility model, the frequency band of the wireless communication between the wireless sensor node and the wireless temperature measuring collector is 433 MHz, the communication protocol is IEEE802.15.4g, and the authentication is performed through a key.

The utility model also provides a monitoring method for on-line monitoring of the temperature of the intermediate joint of buried cables, which includes the following steps:

(1) The thermoelectric generator TEG converts the temperature difference between its two sides into a voltage signal and outputs it to the energy harvester. The energy harvester converts the weak voltage (20-500mV) into a working voltage for the microcontroller and the first wireless transceiver, and the average output power P _OUT is about 1.5-2.5mW when the temperature difference between the two sides of the TEG is 5°C ( The specific value depends on the parameters of the TEG). Since P _OUT cannot maintain the wireless sensor node to work in normal mode in most cases, the node can only work with a certain duty cycle. The capacitor C _OUT at the output end of the energy harvester can ensure that V _OUT will not drop below normal operation after the wireless sensor node works at maximum power for a period of time. The value of C _OUT can be determined by the following formula:

C _OUT = I _PULSE *t _PULSE /ΔV _OUT ;

Among them: I _PULSE and t _PULSE are the maximum working current of the wireless sensor node and its corresponding working time, and ΔV _OUT is the maximum voltage drop allowed by the V _OUT output terminal.

If the power consumption of the wireless sensor node during normal operation is P _N , its working duty cycle should be smaller than P _OUT /P _N .

If the average power consumption of the wireless sensor node is P _Q when it works with a fixed duty cycle, then when the output voltage of the thermoelectric generator TEG is less than 20mV, the energy stored in the supercapacitor can maintain the working time of the node as:

t _S ＝C _STORE *(5.25V-3.3V)/P _Q ;

Among them: C _STORE is the capacitance value of the supercapacitor.

(2) Wireless sensor nodes upload monitoring data to the wireless temperature measurement concentrator in a point-by-point manner: each wireless sensor node in the cable channel has a unique number and location information. The data upload adopts a point-by-point collection method: suppose the node number farthest from the temperature measurement concentrator is 1, followed by 2, and the number closest to the temperature measurement concentrator is N; when uploading temperature data, the first node is No. 1 Send the data to node 2, then node 2 sends node 1 and its own data to node 3, and finally node N sends the data of all nodes to the wireless temperature measurement concentrator. All nodes only send data once in a data upload cycle, thus reducing their average power consumption.

(3) After the wireless temperature measurement concentrator receives the data sent by the sensor nodes, it will display it locally, and upload the data to the monitoring center as needed, and provide an alarm function. The user can set the configuration parameters of the wireless sensor node through the LCD screen (such as transmission power, data collection and transmission interval, working mode, time and date, etc.). When the data is sent, the wireless temperature measurement concentrator first transmits the data to the N node , and then passed from node N to node N-1, and finally from node 2 to node 1.

The on-line temperature monitoring system of the buried cable intermediate joint provided by the utility model takes energy collection and wireless sensing technology as the core, and converts the temperature difference between the skin of the cable intermediate joint and the environment through a thermoelectric generator and an energy collector into electric energy to supply power for the wireless sensor , thus eliminating the battery in the sensor, making it maintenance-free, safe and reliable, and easy to install.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit them. Although the present utility model has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible Any modification or equivalent replacement made to the specific implementation of the present utility model without departing from the spirit and scope of the present utility model shall be covered by the claims of the present utility model.

Claims (9)

1. a underground cable Joint Temperature on-line monitoring system, described system comprises N wireless sensing node, thermoelectric generator and the wireless temperature measurement manifold that is arranged at the aboveground side of cable work, it is characterized in that, cable intermediate joint is arranged at cable work downhole, and single wireless sensing node and thermoelectric generator are installed on the outside surface of cable intermediate joint successively side by side; Described wireless temperature measurement manifold is installed in switching station, ring main unit or the cable branch box of cable termination, take-off connection, and its Antenna extender is collected the Monitoring Data of wireless sensor node to conduit line.

2. temperature online monitoring system as claimed in claim 1, is characterized in that, the side that described thermoelectric generator temperature is high sticks on cable intermediate joint exocuticle, and the side that temperature is low is diffused into hot-fluid in air by heating radiator; Between adjacent cable intermediate head, distance is 100～400 meters.

3. temperature online monitoring system as claimed in claim 1, is characterized in that, described single wireless sensor node comprises and connect successively energy harvester, microcontroller and the first wireless transceiver, and semiconductor temperature sensor is connected with microcontroller; Semiconductor temperature sensor and the first wireless transceiver all obtain power supply by the VOUT pin of microcontroller.

4. temperature online monitoring system as claimed in claim 3, is characterized in that, described energy harvester comprises collection of energy managing chip, miniature transformer, super capacitor and capacitor; Described miniature transformer, super capacitor and capacitor are all connected on collection of energy managing chip.

5. temperature online monitoring system as claimed in claim 3, is characterized in that, described semiconductor temperature sensor adopts the sensor of TMP36 model.

6. temperature online monitoring system as claimed in claim 3, is characterized in that, the inner integrated analog digit converter of described microcontroller, timer, general purpose I/O, interruptable controller On-Chip peripheral;

Microcontroller is connected with the first wireless transceiver by serial peripheral SPI interface, and utilizes general purpose I/O to export to close or off signal SDN controls electrification reset and the working power of the first wireless transceiver.

7. temperature online monitoring system as claimed in claim 3, is characterized in that, utilizes thermoelectric generator and energy harvester to convert the temperature difference of cable intermediate joint and environment to electric energy, is described wireless sensor node power supply.

8. temperature online monitoring system as claimed in claim 1, it is characterized in that, described wireless temperature measurement manifold, by the civil power in switching station, ring main unit or cable branch box, PT power supply or storage battery power supply, comprises microprocessor, the second wireless transceiver, GPRS module/fiber optic Ethernet interface, LCD display, radio circuit and antenna; Described the second wireless transceiver, GPRS module/fiber optic Ethernet interface are connected with microprocessor respectively with LCD display, and described antenna is connected with the second wireless transceiver by radio circuit.

9. temperature online monitoring system as claimed in claim 1, is characterized in that, the frequency range of described wireless sensor node and wireless temperature measurement manifold radio communication is 433MHz, and communication protocol is IEEE802.15.4g, and authenticates by key.

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