Wireless passive temperature measurement equipment and method for switch cabinet

Abstract

The invention belongs to the technical field of temperature detection, and particularly relates to a wireless passive temperature measuring device and method for a switch cabinet. The invention relates to an electric power cabinet, a group of sensors are installed in the electric power cabinet, and a panel antenna for receiving and forwarding sensor data is installed on the inner wall of the electric power cabinet at the same time; the wireless temperature collector is arranged in a secondary instrument room arranged in the electric power cabinet; the sensor group comprises an SAW temperature sensor, and a plug type sensor, a contact sensor and a screw joint type sensor which are provided with the SAW temperature sensor; the SAW temperature sensor is used for completing temperature detection and result transmission according to the principle that radio frequency change and temperature change are in proportional relation. According to the invention, the problem that the temperature of the electrical equipment is not monitored in time or cannot be sensed to cause safety accidents can be solved; the problems of the traditional temperature measurement technology in the aspects of safety, reliability, stability, practicability and the like are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature detection, and particularly relates to a wireless passive temperature measurement device and method for switch cabinets. Background Art

[0002] For important equipment such as high-voltage switch cabinets, busbar joints, and outdoor knife switches in power plants and substations, during long-term operation, the contacts of the switches and the busbar connections and other parts heat up due to aging or excessive contact resistance, and the temperature of these heated parts cannot be monitored, which ultimately leads to accidents; in recent years, several switch overheating accidents have occurred in power plants and substations, causing fires and large-scale power outages. Solving the problem of switch overheating is the key to preventing such accidents and realizing on-line temperature monitoring. In addition, after the ring main unit has been in operation for a long time, it is difficult to block the radiation of sunlight, and there is an over-sealed condition inside the ring main unit, which will affect the heat dissipation effect of the ring main unit equipment, resulting in heat accumulation and temperature rise inside the machine, and ultimately damaging the electrical equipment; in the case of large temperature changes, if the current humidity is high, even if the staff installs the infrared thermometer in the ring main unit in advance to monitor the temperature inside the ring main unit, due to its difficulty in measuring the temperature of the outer layer of the cable in real time and effectively, the measured temperature is quite different from the temperature inside the cable, affecting the monitoring effectiveness of the temperature inside the ring main unit; at the same time, even if a device for controlling temperature and humidity is used, condensation will also occur inside the ring main unit equipment, and some equipment will be affected by moisture and cause flashover or ladder climbing accidents, and more seriously, other accidents such as burning will occur, which needs to be improved.

[0003] Problems Faced by Traditional Temperature Measurement Methods Conventional temperature measurement methods: Conventional temperature measurement methods such as thermocouples, thermal resistors, and semiconductor temperature sensors require metal wires to transmit signals, and the insulation performance cannot be guaranteed. Comparison with optical fiber temperature measurement: The optical fiber temperature sensor uses optical fibers to transmit temperature signals. Optical fibers have excellent insulation performance and can isolate the high voltage inside the switch cabinet. Therefore, the optical fiber temperature sensor can be directly installed on the high-voltage contacts inside the switch cabinet to accurately measure the operating temperature of the high-voltage contacts and realize on-line monitoring of the operating temperature of the switch cabinet contacts; however, optical fibers are prone to breakage, are not resistant to high temperatures, etc.; after accumulating dust, it is easy to cause surface discharge along the optical fiber, reducing the insulation, and affected by the structure of the switch cabinet, the wiring inside the cabinet is difficult; in addition, the cost of optical fiber temperature measurement is relatively high. Infrared temperature measurement Infrared temperature measurement is a non-contact temperature measurement method, which is vulnerable to environmental and surrounding electromagnetic field interference. In addition, the space inside the switchgear cabinet is very narrow, making it impossible to install an infrared temperature measurement probe (because the probe must maintain a certain safe distance from the object to be measured and needs to be directly facing the surface of the object to be measured). It is required that the measurement point can be within the field of view without obstruction and the surface is clean to ensure accuracy. Active wireless temperature measurement The size of active wireless temperature sensors is usually relatively large and the batteries need to be replaced frequently, resulting in a relatively high system maintenance cost. At the same time, the batteries are not suitable for working in high-temperature environments, especially those above 150 degrees Celsius. Summary of the Invention

[0004] The purpose of the present invention is to provide a wireless passive temperature measurement device and method for switchgear cabinets, which can solve the pain points of untimely temperature monitoring or inability to sense electrical equipment, leading to safety accidents, and effectively solve the problems existing in traditional temperature measurement technologies in terms of safety, reliability, stability, and practicality.

[0005] The technical solutions adopted by the present invention are as follows: A wireless passive temperature measurement device for switchgear cabinets, comprising: A power cabinet, inside which a group of sensors are installed, and a flat antenna for receiving and forwarding sensor data is installed on the inner wall of the power cabinet. A wireless temperature collector, which is installed inside the secondary instrument room opened inside the power cabinet, used to transmit a temperature measurement inquiry radio frequency signal to the sensor, receive the return signal from the temperature sensor, and parse it into temperature information and send it back to the temperature monitoring master station software system. The sensor group includes SAW temperature sensors, as well as plug-type sensors, contact sensors, and screw-connected sensors equipped with SAW temperature sensors. The plug-type sensors, contact sensors, and screw-connected sensors are respectively installed at the corresponding contact points inside the power cabinet. The SAW temperature sensor outputs a radio frequency signal that changes proportionally with the temperature. This radio frequency signal forms a return signal transmitted to the wireless temperature collector through the flat antenna, which is used to complete the temperature detection and result transmission work.

[0006] The inside of the power cabinet includes a cable end, a mobile circuit breaker, a busbar, and a secondary instrument room. A circuit breaker is provided at the connection end of the cable end.

[0007] The plug-type sensor is installed at the contact point at the end of the cable end.

[0008] The contact sensor is installed on the outer wall of the corresponding contact of the mobile circuit breaker, and the types of contact sensors include strapped sensors installed using cable ties, flat sensors, and T-type sensors.

[0009] The screw-connected sensor is installed at the contact point corresponding to the cable end and the breaker, and the types of the screw-connected sensors include a duckbill breaker sensor installed by using a cable tie, a hole-type busbar sensor, and a fork-type busbar sensor. Among them, the duckbill breaker sensor is installed at the contact point corresponding to the breaker, and one of the hole-type busbar sensor or the fork-type busbar sensor is installed at the contact point corresponding to the cable end.

[0010] The SAW temperature sensor internally includes a piezoelectric inductor. In the middle of the surface of the piezoelectric inductor, an interdigital transducer for activating surface waves is provided, and both ends of the interdigital transducer are connected with internal antennas for transmitting and receiving signals. Reflectors are provided at both ends of the surface of the piezoelectric inductor.

[0011] It further includes a local temperature measurement master control terminal. Multiple power cabinets in the same area form one of a CAN bus network or a wireless ad hoc network through wireless temperature collectors for local data transmission, and then the local temperature measurement master control terminal uniformly collects, stores, and manages the temperature monitoring information of all power cabinets in this area.

[0012] A display terminal is fixedly installed on the outer wall of the secondary instrument room, and the display terminal is used to complete the data management, parameter setting, temperature data analysis of the sensor group and the wireless temperature collector, and provide a data interface with the automation system. The display terminal is data-connected to the corresponding data transmission device through a communication module.

[0013] A magnet is embedded in the outer wall of the flat antenna.

[0014] A method for wireless passive temperature measurement of a switch cabinet is as follows: Step 1: The wireless temperature collector transmits a radio frequency pulse through the flat antenna, and the radio frequency pulse is received by all SAW temperature sensors in its area. Step 2: After the pulse signal is received by the internal antenna in the SAW temperature sensor, a surface wave is activated on the surface of the piezoelectric inductor through the interdigital transducer. Step 3: The frequency of the surface wave on the piezoelectric inductor changes due to the influence of the temperature of the sensor itself, and it is precisely due to the mechanism of the frequency being affected by temperature changes that the temperature data measurement is realized. Step 4: The interdigital transducer then converts the frequency oscillation of the surface wave into a radio frequency signal, and this radio frequency signal is received by the flat antenna connected to the wireless temperature collector and then processed. Step 5: A group of sensors are installed inside a power cabinet to measure the temperatures of each contact point, and the wireless temperature collector uniformly completes the sending, receiving, and management of the temperature monitoring information of this group of sensors. Step 6: Multiple power cabinets in the same area form one of a CAN bus network or a wireless ad-hoc network through wireless temperature collectors for local data transmission, and then the local temperature measurement master terminal uniformly collects, stores, and manages the temperature monitoring information of all power cabinets in this area; Step 7: The local temperature measurement master terminal can either display the temperature information locally through an LCD display screen or transmit it to the monitoring center through a data interface to achieve remote online temperature monitoring, analysis, and early warning.

[0015] The technical effects achieved by the present invention are: The advantages of the passive wireless temperature measurement proposed by the present invention are: No battery required: The SAW sensor uses a passive induction method and does not require battery drive, reducing the maintenance cost brought by battery replacement. At the same time, it will not have an impact on the ecological environment. By utilizing the surface acoustic wave characteristics of piezoelectric materials, a passive wireless surface acoustic wave temperature sensor can be realized, which can monitor the positions such as power grid cable joints and switch cabinet contacts in real time, greatly improving the safe operation of the power grid.

[0016] Safe and reliable: Thus, high-voltage isolation is achieved to ensure the safe operation of the equipment.

[0017] Convenient and flexible installation: The passive wireless temperature sensor is small in size and has wireless data transmission with the collector, making the installation convenient and flexible, and not affected by the structure and space of the switch cabinet.

[0018] Good environmental adaptability: After calibration by the matching software, the temperature sensor has compensated for the deviation during the sensor manufacturing process; the sensor can be debugged at any temperature within the working temperature range and is not affected by seasonal factors; usually, the sensor is only debugged once after installation and does not need to be calibrated again for many years; at the same time, environmental factors such as dust accumulation will not affect the temperature measurement of the SAW sensor.

[0019] Low cost: The price of the SAW sensor is lower than other traditional temperature measurement methods. At the same time, the passive wireless working method greatly reduces the installation and maintenance costs of this system. Description of the Drawings

[0020] Figure 1 is the internal composition plan view of the power cabinet provided by the embodiment of the present invention; Figure 2 is the structural diagram of the SAW temperature sensor provided by the embodiment of the present invention; Figure 3 is the communication method view provided by the embodiment of the present invention; Figure 4 is the terminal fixed wiring and module connection diagram provided by the embodiment of the present invention; Figure 5Schematic diagram of the installation position of the plug - type sensor provided by the embodiment of the present invention; Figure 6 Structural diagram of the flat antenna provided by the embodiment of the present invention; Figure 7 Front and back views of the plug - type sensor provided by the embodiment of the present invention; Figure 8 Schematic diagram of the installation position of the contact sensor provided by the embodiment of the present invention; Figure 9 Type diagram of the contact sensor provided by the embodiment of the present invention; Figure 10 Schematic diagram of the installation position of the screw - type sensor provided by the embodiment of the present invention; Figure 11 Type diagram of the screw - type sensor provided by the embodiment of the present invention.

[0021] In the drawings, the list of components represented by each reference numeral is as follows: 1, power cabinet; 101, cable end; 102, mobile circuit breaker; 103, bus bar; 104, secondary instrument room; 105, breaker; 2, SAW temperature sensor; 201, piezoelectric inductor; 202, interdigital transducer; 203, reflector; 204, internal antenna; 3, flat antenna; 301, magnet; 4, wireless temperature collector; 5, display terminal; 6, data transmission device; 7, local temperature measurement master terminal; 8, communication module; 9, plug - type sensor; 10, contact sensor; 1001, bundled sensor; 1002, flat - type sensor; 1003, T - type sensor; 11, screw - type sensor; 1101, duck - bill breaker sensor; 1102, hole - type bus bar sensor; 1103, fork - type bus bar sensor. Detailed implementation manners

[0022] In order to make the purpose and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific implementation manners of the present invention, and does not strictly limit the scope of protection specifically claimed by the present invention.

[0023] As Figures 1-11 shown, a wireless passive temperature - measuring device for switchgear includes: Referring to the attached Figure 1 , power cabinet 1, a group of sensors are installed inside the power cabinet 1. The inside of the power cabinet 1 includes a cable end 101, a mobile circuit breaker 102, a bus bar 103, and a secondary instrument room 104. A breaker 105 is provided at the connection end of the cable end 101.

[0024] Referring to the attached Figure 2, the sensor group includes a SAW temperature sensor 2, a plug-type sensor 9 with the SAW temperature sensor 2 installed thereon, a contact sensor 10, and a screwed sensor 11; the SAW temperature sensor 2 outputs a radio frequency signal that changes proportionally with the temperature change, and this radio frequency signal forms a return signal transmitted to the wireless temperature collector 4 through the planar antenna 3, which is used to complete the work of temperature detection and result transmission. Inside the SAW temperature sensor 2, there is a piezoelectric inductor 201. In the middle of the surface of the piezoelectric inductor 201, there is an interdigital transducer 202 for activating surface waves, and both ends of the interdigital transducer 202 are connected to internal antennas 204 for signal transmission and reception. Reflectors 203 are provided at both ends of the surface of the piezoelectric inductor 201.

[0025] Refer to the appendix Figures 5-6 , on the inner wall of the power cabinet 1, a planar antenna 3 for receiving and forwarding sensor data is installed at the same time. A magnet 301 is embedded on the outer wall of the planar antenna 3.

[0026] According to the above structure, the transceiver planar antenna 3 of the collector is used to send and receive electromagnetic wave signals to complete the signal transmission between the wireless temperature collector 4 and the sensor. After the passive wireless planar antenna 3 is adsorbed on the cabinet wall using the magnet 301, it is fastened with screws. In addition, the effective wireless communication range between the planar antenna 3 and the SAW temperature sensor 2 is 2 meters.

[0027] Refer to the appendix Figures 4-5 , a wireless temperature collector 4 is installed inside the secondary instrument room 104 opened inside the power cabinet 1, which is used to transmit a temperature measurement inquiry radio frequency signal to the sensor, receive the return signal of the temperature sensor, and parse it into temperature information and send it back to the temperature monitoring master station software system.

[0028] According to the above structure, the planar antenna 3 of the wireless temperature collector 4 is embedded in the inner wall of the switch cabinet, so that external radio wave interference can be shielded. The other part of the wireless temperature collector 4, the receiving box, can be installed outside the power cabinet 1 or inside the secondary instrument room 104; the wireless temperature collector 4 is powered by a separate power supply and emits a short radio frequency signal into the switch cabinet. If the frequency of the radio frequency pulse is the same as the preset frequency of the temperature sensor, the sensor can receive this radio frequency signal and change and passively reflect the pulse signal. The returned pulse signal carries the temperature information of the sensor because it is affected by the temperature of the sensor itself. Install various sensors equipped with the SAW temperature sensor 2 at the corresponding contact points inside the power cabinet 1. The SAW temperature sensor 2 directly obtains the temperature of the contact point by directly contacting the contact point. First, the wireless temperature collector 4 emits radio frequency pulses through the flat antenna 3, and the radio frequency pulses are received by all the SAW temperature sensors 2 within its area. After the pulse signal is received by the internal antenna 204 inside the SAW temperature sensor 2, a surface wave is activated on the surface of the piezoelectric inductor 201 through the interdigital transducer 202. The frequency of the surface wave on the surface of the piezoelectric inductor 201 changes due to the influence of the temperature of the sensor itself. And precisely because of the mechanism of the frequency being affected by temperature changes, the temperature data measurement can be realized. The interdigital transducer 202 then converts the frequency oscillation of the surface wave into a radio frequency signal. This radio frequency signal is received by the flat antenna 3 connected to the wireless temperature collector 4 and then processed. The wireless temperature collector 4 analyzes the returned signal of the temperature sensor received and sends the temperature information back to the temperature monitoring master station software system; This temperature detection method adopts a passive induction method, does not require battery drive, reduces the maintenance cost brought by battery replacement, and at the same time will not have an impact on the ecological environment; realizes high-voltage isolation and ensures the safe operation of the equipment; has a small volume and wireless data transmission with the collector, is convenient and flexible to install, and is not affected by the structure and space of the switch cabinet; can be debugged at any temperature within the working temperature range, is not affected by seasonal factors, and the maintenance cost is also greatly reduced.

[0029] Refer to the appendix Figures 4-5 , and also includes a local temperature measurement main control terminal 7. Multiple power cabinets 1 in the same area form one of a CAN bus network or a wireless ad hoc network through the wireless temperature collectors 4 for local data transmission, and then the local temperature measurement main control terminal 7 uniformly collects, stores, and manages the temperature monitoring information of all the power cabinets 1 in this area; A display terminal 5 is fixedly installed on the outer wall of the secondary instrument room 104, and the display terminal 5 is used to complete the data management, parameter setting, temperature data analysis of the sensor group and the wireless temperature collector 4, and provide a data interface with the automation system. The display terminal 5 is data-connected to the corresponding data transmission device 6 through the communication module 8.

[0030] According to the above structure, a group of sensors are installed inside a power cabinet 1 to measure the temperature of each contact. The wireless temperature collector 4 uniformly completes the sending, receiving, and management of the temperature monitoring information of this group of sensors. Multiple power cabinets 1 in a region form one of a CAN bus network or a wireless ad-hoc network through the wireless temperature collector 4 for local data transmission. Then, the local temperature measurement master terminal 7 uniformly collects, stores, and manages the temperature monitoring information of all power cabinets 1 in this region. The local temperature measurement master terminal 7 can either locally display the temperature information through an LCD display screen or transmit it to the monitoring center through a data interface to achieve remote online temperature monitoring, analysis, and early warning.

[0031] Refer to the appendix Figure 5 、 Figure 8 and Figure 10 , the plug-type sensor 9, the contact sensor 10, and the screw-connected sensor 11 are respectively installed at the corresponding contacts inside the power cabinet 1; Refer to the appendix Figure 5 and Figure 7 , the plug-type sensor 9 is installed at the contact of the end of the cable end 101.

[0032] Refer to the appendix Figure 8 and Figure 9 , the contact sensor 10 is installed on the outer wall of the corresponding contact of the mobile circuit breaker 102, and the types of the contact sensor 10 include the bundled sensor 1001 installed by using a cable tie, the flat sensor 1002, and the T-type sensor 1003.

[0033] Refer to the appendix Figure 10 and Figure 11 , the screw-connected sensor 11 is installed at the corresponding contact of the cable end 101 and the breaker 105, and the types of the screw-connected sensor 11 include the duckbill breaker sensor 1101 installed by using a cable tie, the hole-type busbar sensor 1102, and the fork-type busbar sensor 1103. Among them, the duckbill breaker sensor 1101 is installed at the corresponding contact of the breaker 105, and one of the hole-type busbar sensor 1102 or the fork-type busbar sensor 1103 is installed at the corresponding contact of the cable end 101.

[0034] According to the above structure, the plug-type sensor 9, the contact sensor 10, and the screw-connected sensor 11 are temperature measuring elements directly installed on the surface of the object to be measured, and are respectively designed with structures adapted to the corresponding contacts. The common point is that they are all equipped with SAW temperature sensors 2 inside. All the sensors located inside a power cabinet 1 perform wireless data transmission with the wireless temperature collector 4 inside its cabinet body to achieve the measurement of the temperature of various types of contacts inside the power cabinet 1.

[0035] Installation of the temperature measurement device of the present invention: Taking the plug-type sensor 9 as an example, install the plug-type sensor 9 of the SAW temperature sensor 2 on the cable plug of the power cabinet 1, and make the fastening part between the sensor and the plug closely combined; Place the wireless temperature collector 4 in the secondary instrument room 104 of the power cabinet 1. The wireless temperature collector 4 is connected to the local temperature display and warning terminal by a 485 bus. The 485 connecting wire is laid flat in the wire duct, and a suitable wire routing diameter is selected to make the distance the shortest; After the wireless temperature collector 4 and the flat antenna 3 of a power cabinet 1 are installed, use the tool software to set the address parameters, temperature calibration and verification. When the inspection is correct, record the corresponding data, and the temperature measurement device of this power cabinet 1 is completed with installation and configuration.

[0036] A wireless passive temperature measurement method for switch cabinets is as follows: Step 1: The wireless temperature collector 4 emits radio frequency pulses through the flat antenna 3, and the radio frequency pulses are received by all SAW temperature sensors 2 within its area; Step 2: After the pulse signal is received by the internal antenna 204 of the SAW temperature sensor 2, a surface wave is activated on the surface of the piezoelectric inductor 201 through the interdigital transducer 202; Step 3: The frequency of the surface wave on the surface of the piezoelectric inductor 201 changes due to the influence of the temperature of the sensor itself, and it is precisely due to the mechanism of the frequency being affected by temperature changes that the temperature data measurement can be realized; Step 4: The interdigital transducer 202 then converts the frequency oscillation of the surface wave into a radio frequency signal, and this radio frequency signal is received by the flat antenna 3 connected to the wireless temperature collector 4 and then processed; Step 5: A group of sensors are installed inside a power cabinet 1 to measure the temperatures of each contact point, and the transceiver and management of the temperature monitoring information of this group of sensors are uniformly completed by a wireless temperature collector 4; Step 6: Multiple power cabinets 1 in the same area form one of a CAN bus network or a wireless ad hoc network through the wireless temperature collectors 4 for local data transmission, and then the local temperature measurement main control terminal 7 uniformly collects, stores and manages the temperature monitoring information of all power cabinets 1 in this area; Step 7: The local temperature measurement main control terminal 7 can either locally display the temperature information through an LCD display screen or transmit it to the monitoring center through a data interface to realize remote online temperature monitoring, analysis and warning.

[0037] The working principle of the present invention is: The significance of this temperature measurement method is that through the application of a passive wireless temperature online monitoring system and in combination with other relevant systems and standards, the following application functions can be realized: First, the condition-based maintenance of high-voltage switch cabinets When abnormal conditions are found in the temperatures of the contacts of the switchgear, other relevant operating data such as real-time load data are called, and with the help of a fault diagnosis expert system, comprehensive data analysis and fault diagnosis can be carried out to achieve the condition-based maintenance of high-voltage switchgear: breaking the traditional regular maintenance mode, formulating different maintenance strategies for switchgear in different states, including maintenance time and maintenance items, and ultimately ensuring the safe and stable operation of equipment more effectively; Second, the formation and improvement of relevant technical standards for high-voltage switchgear Installing a passive wireless temperature on-line monitoring system in the switchgear can monitor the operating temperature condition of the switchgear in real time and timely detect and collect abnormalities during operation; By comparing the temperature data of switchgears of a large number of different manufacturers, models, structures, and installation methods, it can assist in analyzing the quality of switchgears of different manufacturers, the operating stability of switchgears of different models in different operating environments, and the impact of different installation methods on the operation of switchgears, etc.; Thus, it actively promotes the formation and improvement of relevant technical standards for high-voltage switchgear; Third, timely update and acquisition of data The system sets an automatic acquisition task to regularly collect the temperature information of the switchgear according to the established sampling frequency; The temperature data is stored in the database, and users can set a time interval and specify a monitoring object to query historical temperature information; At the same time, users can specify a specific switchgear or sensor in the master station system to collect real-time temperature information; When the absolute value of the switchgear temperature or the rate of change of the temperature exceeds the upper limit, the system provides alarm information in various ways such as sound, photoelectricity, and text messages for operation and management personnel; Timely or predictive discovery and elimination of faults, thus ensuring the safe and stable operation of power equipment to the greatest extent.

[0038] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention are implemented according to the conventional means in the art without special description and limitation.

Claims

1. A wireless passive temperature measurement device for switchgear, characterized in that, Comprising: A power cabinet (1), inside which a group of sensors are installed, and a flat antenna (3) for receiving and forwarding sensor data is installed on the inner wall of the power cabinet (1); A wireless temperature collector (4), which is installed inside a secondary instrument room (104) opened inside the power cabinet (1), is used to transmit a temperature measurement inquiry radio frequency signal to the sensor, receive the return signal of the temperature sensor, and parse it into temperature information and send it back to the temperature monitoring master station software system; The sensor group includes a SAW temperature sensor (2), a plug-type sensor (9) equipped with the SAW temperature sensor (2), a contact sensor (10), and a screw-connected sensor (11), and the plug-type sensor (9), the contact sensor (10), and the screw-connected sensor (11) are respectively installed at the corresponding contact points inside the power cabinet (1); The SAW temperature sensor (2) outputs a radio frequency signal that changes proportionally to the temperature change, and this radio frequency signal forms a return signal transmitted to the wireless temperature collector (4) through the flat antenna (3), which is used to complete the work of temperature detection and result transmission.

2. The wireless passive temperature measurement device for switchgear according to claim 1, characterized in that: Inside the power cabinet (1), there are a cable end (101), a mobile circuit breaker (102), a busbar (103), and a secondary instrument room (104), and a disconnector (105) is provided at the connection end of the cable end (101).

3. The wireless passive temperature measurement device for switchgear according to claim 2, characterized in that: The plug-type sensor (9) is installed at the contact point at the end of the cable end (101).

4. The wireless passive temperature measurement device for switchgear according to claim 2, characterized in that: The contact sensor (10) is installed on the outer wall of the corresponding contact of the mobile circuit breaker (102), and the types of the contact sensor (10) include a bundled sensor (1001) installed by bundling with a cable tie, a flat sensor (1002), and a T-shaped sensor (1003).

5. The wireless passive temperature measurement device for switchgear according to claim 2, characterized in that: The screw-connected sensor (11) is installed at the contact point corresponding to the disconnector (105) of the cable end (101), and the types of the screw-connected sensor (11) include a duckbill disconnector sensor (1101) installed by bundling with a cable tie, a hole-type busbar sensor (1102), and a fork-type busbar sensor (1103), wherein the duckbill disconnector sensor (1101) is installed at the contact point corresponding to the disconnector (105), and either the hole-type busbar sensor (1102) or the fork-type busbar sensor (1103) is installed at the contact point corresponding to the cable end (101).

6. The wireless passive temperature measurement device for switchgear according to claim 5, characterized in that: Inside the SAW temperature sensor (2), there is a piezoelectric inductor (201). In the middle of the surface of the piezoelectric inductor (201), there is an interdigital transducer (202) for activating surface waves, and both ends of the interdigital transducer (202) are connected to an internal antenna (204) for transmitting and receiving signals. Reflectors (203) are provided at both ends of the surface of the piezoelectric inductor (201).

7. A wireless passive temperature measurement device for a switch cabinet according to claim 6, characterized in that: It further includes a local temperature measurement master terminal (7). Multiple power cabinets (1) in the same area form one of a CAN bus network or a wireless ad hoc network through wireless temperature collectors (4) for local data transmission, and then the local temperature measurement master terminal (7) uniformly collects, stores, and manages the temperature monitoring information of all power cabinets (1) in this area.

8. A wireless passive temperature measurement device for switchgear according to claim 7, characterized in that: A display terminal (5) is fixedly installed on the outer wall of the secondary instrument room (104), and the display terminal (5) is used to complete data management, parameter setting, temperature data parsing of the sensor group and the wireless temperature collector (4), and provide a data interface with the automation system. The display terminal (5) is data-connected to the corresponding data transmission device (6) through a communication module (8).

9. The wireless passive temperature measurement device for switchgear according to claim 8, characterized in that: A magnet (301) is embedded in the outer wall of the flat antenna (3).

10. A wireless passive temperature measurement method for a switchgear, using the wireless passive temperature measurement device for a switchgear as described in claim 9, characterized in that, The specific steps are as follows: Step 1: The wireless temperature collector (4) emits radio frequency pulses through the flat antenna (3), and the radio frequency pulses are received by all SAW temperature sensors (2) in its area. Step 2: After the pulse signal is received by the internal antenna (204) inside the SAW temperature sensor (2), a surface wave is activated on the surface of the piezoelectric inductor (201) through the interdigital transducer (202). Step 3: The frequency of the surface wave on the surface of the piezoelectric inductor (201) changes due to the influence of the temperature of the sensor itself, and it is precisely due to the mechanism of the frequency being affected by temperature changes that the temperature data measurement is realized. Step 4: The interdigital transducer (202) then converts the frequency oscillation of the surface wave into a radio frequency signal, and this radio frequency signal is received and processed by the flat antenna (3) connected to the wireless temperature collector (4). Step 5: A group of sensors for measuring the temperature of each contact is installed inside a power cabinet (1), and the transceiver and management of the temperature monitoring information of this group of sensors are uniformly completed by a wireless temperature collector (4). Step 6: Multiple power cabinets (1) in the same area form one of a CAN bus network or a wireless ad hoc network through wireless temperature collectors (4) for local data transmission, and then the local temperature measurement master terminal (7) uniformly collects, stores, and manages the temperature monitoring information of all power cabinets (1) in this area. Step 7: The local temperature measurement master terminal (7) can either perform local display of temperature information through the LCD display screen or be transmitted to the monitoring center through the data interface to realize remote online temperature monitoring, analysis, and early warning.

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