Railway contact network key area temperature measurement method

Abstract

The invention relates to the field of railway catenary safety monitoring, discloses a railway catenary key area temperature measuring method, and aims to monitor the temperature of a catenary key area in real time and prevent operation accidents caused by overheating. The system has the functions of self-power supply, high-precision temperature measurement and wireless data transmission; a wireless receiving device developed in a matched mode can receive temperature data and remotely forward the temperature data to a cloud server, and a server framework and an intelligent monitoring background are built on a cloud platform and used for receiving, storing, processing and analyzing the data. An early warning threshold value is set in the background, and once the temperature data exceeds the standard, an early warning mechanism is triggered. According to the method, real-time monitoring and early warning of the temperature of the key area of the overhead line system are achieved, dependence of manual detection is effectively reduced, and safety and stability of railway operation are improved.

Description

Technical Field

[0001] The present invention relates to the field of railway contact network safety monitoring, and specifically to a method for measuring temperature in key areas of a railway contact network. Background Art

[0002] During the operation of electrified railways, the traction power supply system provides electric energy to the train through the contact network. The traction current enters the train through the pantograph, then flows into the rail through the wheelset, and flows back to the substation through the traction return system composed of the rail, suction line, return line, etc. In recent years, with the development of my country's high-speed railways and heavy-duty railways, the traction load of the traction power supply system has continued to increase, resulting in the continuous increase in the capacity of the traction substation. On the one hand, it causes the traction load current to increase under normal circumstances; on the other hand, when a short-circuit fault occurs, the short-circuit current also increases. The contact network feeder point is the key point where the power supply line and the contact network are connected, and it is also one of the points where the current is most concentrated and the current changes most dramatically. If the wire clamp or (copper, aluminum) stranded wire at the access point is aged, oxidized, dirty, loose, or has poor contact, it may cause serious consequences such as arcing, discharge, tripping, and even melting of the aluminum stranded wire. The above phenomenon will be accompanied by an increase in temperature. Therefore, it is necessary to strengthen the monitoring intensity and frequency of the contact network feeder point temperature to ensure the safe and stable operation of the contact network equipment.

[0003] Since the contact network feeder outlets are located above the contact network, most of which are over 10 meters high, conventional methods such as manual temperature guns and infrared imagers are inaccurate for long-distance temperature measurement. It is impossible to monitor the excessive temperature of the contact network feeder outlets in real time, and it is impossible to provide real-time warnings.

[0004] The most effective way to solve railway operation accidents caused by overheating of contact network feeder points is to monitor the temperature status of contact network feeder points. At present, there are several methods for monitoring the temperature of contact network feeder points at home and abroad:

[0005] (1) WJY-II type contact network temperature monitoring device. This method can only collect temperature data of contact network feeder points using a PC while riding on a train, or collect data by riding in a car on a road parallel to the railway. It is impossible to achieve real-time monitoring of the temperature status of contact network feeder points.

[0006] (2) Use color-changing temperature measuring patches to monitor the points on the contact network feeder. However, before it is put into use, the contact network maintenance personnel need to be trained on the key points of using color temperature measuring patches. After the training, the contact network maintenance personnel must conduct regular inspections to analyze and judge the overheating of the electrical nodes of the contact network main circuit by inspecting the color change of the temperature measuring patches. However, this method cannot monitor the temperature rise process of the points on the contact network feeder. If temperature abnormalities occur outside the inspection plan, hidden dangers will still not be discovered in time.

[0007] (3) Infrared temperature monitoring method for electrified railway contact network, using non-contact infrared thermal imaging measurement technology to monitor the temperature of contact network feeder points. The degree of damage caused by abnormal temperature rise during live operation of contact network feeder points can be observed through infrared thermal images. However, the measurement accuracy of infrared thermal imaging technology is easily affected by the environment. Considering the complex working environment and environmental climate of the contact network, the practical promotion of this method is general. In addition, the contact network maintenance personnel must be proficient in operating infrared image analysis software, and need to evaluate the collected infrared images of the contact network and put forward treatment opinions in a short time, which undoubtedly increases the complexity and intensity of the contact network maintenance work.

[0008] (4) The non-contact online monitoring system of surface acoustic wave technology uses the working temperature of the network point on the contact network feeder line of the surface acoustic wave sensor under the condition of high ambient temperature, low wind speed and strong electric load, and transmits the temperature information to the data center through the wireless network. However, due to the complexity of electromagnetic wave propagation and the complexity and changeability of electromagnetic interference, this solution has strict requirements on the working environment, and the promotion of this measurement technology still needs sufficient practice to test.

[0009] (5) Catenary optical fiber temperature monitoring system, which is used on the German ICE3 high-speed railway line. This system allocates an independent optical fiber to each fiber Bragg grating (FBG) sensor. The fiber Bragg grating (FBG) sensor collects temperature data and transmits it to the computer in the traction substation via optical fiber. The disadvantage of this solution is that the performance requirements of the optical fiber are too high and the project cost is expensive.

[0010] (6) Norway installs an infrared camera on the top of the train to take infrared images of the contact network feeder points while the train is moving, and compares them with the temperature map of normal contact network components to find abnormal temperature rise components. Since infrared rays cannot penetrate opaque objects, when the contact network feeder points are in an environment such as sand, haze or dense fog, it will affect the judgment of the actual temperature rise of the contact network feeder points and affect the imaging effect.

[0011] At present, there is no widely used monitoring method for the temperature of the contact network clamp at home and abroad, and the monitoring methods have certain disadvantages, such as the inability to monitor in real time, the immature technology of the monitoring device, the backward monitoring method, and the high dependence on manual detection. Therefore, we propose a temperature measurement method for the key area of ​​the railway contact network. Summary of the invention

[0012] The purpose of the present invention is to provide a method for measuring temperature in key areas of a railway contact network to solve the problems raised in the above-mentioned background technology.

[0013] Electrical connection devices are generally installed at the anchor joints of the contact network, between the tracks of the station, and in the sections with large current intake of locomotives. The main function of the electrical connection device is to connect the circuits between the suspension parts so that the circuits are fully conductive. As an important component of the electrical connection device, the electrical connection wire clamp plays an important role in conductive connection in the contact network system. Due to its harsh working environment, long-term operation will cause the wire clamp to loosen or even have poor contact, increase the contact resistance at the electrical connection wire clamp, cause the wire clamp to heat up, and cause accidents such as wire burns or even wire breakage. Therefore, ensuring that the temperature of the electrical connection wire clamp is within a safe range is of great significance to the normal operation of the contact network.

[0014] To achieve the above object, the present invention provides the following technical solution: a method for measuring temperature in a key area of ​​a railway contact network, the method comprising the following specific steps:

[0015] Step 1: Design and manufacture a passive wireless temperature collector, the size of which meets the requirements of the contact network equipment clamp and has the functions of self-power supply, high-precision temperature measurement and wireless data transmission; the temperature collector includes a temperature sensing unit, an energy collection unit, a wireless transmission unit and an energy storage unit;

[0016] The temperature sensing unit includes a temperature sensor for real-time temperature collection of the key area, and the temperature sensing unit converts the analog signal sent by the temperature sensor into a temperature value through calculation; the energy collection unit uses electromagnetic induction technology to obtain energy from the AC magnetic field of the contact network feeder to provide power input for the temperature collector; the wireless transmission unit is responsible for transmitting the data collected by the temperature sensor to the outside; the energy storage unit is used to obtain and store excess energy from the energy collection unit for use in high-power consumption operations;

[0017] Step 2: Develop a wireless receiving device that is compatible with the temperature collector. The device is used to receive the temperature data wirelessly transmitted by the temperature collector, and a communication module is installed inside the wireless receiving device. The communication module is used to remotely forward the received temperature data to the cloud server.

[0018] Step 3: Build a server architecture for data reception, storage and processing on the cloud platform, and establish an intelligent monitoring background to analyze the temperature data sent by the temperature collector;

[0019] Step 4: Set the warning thresholds for temperature difference, temperature rise and instantaneous temperature rise in the intelligent monitoring background. When the monitored temperature data exceeds the set warning threshold, the warning mechanism is triggered;

[0020] Step 5: Install the passive wireless temperature collector described in step 1 in the key area of ​​the railway contact network, collect temperature data of the key area of ​​the contact network in real time through the temperature collector, and send the data to the wireless receiving device described in step 2 through wireless transmission. The wireless receiving device further forwards the data to the cloud server for storage and analysis. Users can view temperature information and receive early warning notifications in real time through terminal devices.

[0021] Preferably, the temperature sensing unit adopts temperature measurement methods including temperature measurement using thermochromic materials, thermocouples, thermistors, optical fiber, digital sensors and surface acoustic waves.

[0022] Preferably, the energy collection unit relies on a current transformer to induce an AC voltage from a high-voltage bus, and obtains a low-voltage DC power supply required by the temperature collector from the high-voltage bus through an impact protection circuit, an energy discharge circuit, a rectifier circuit, a filter circuit and a DC-DC conversion circuit.

[0023] Preferably, the energy collection unit selects nanocrystalline material as the core material of the induction coil.

[0024] Preferably, the wireless receiving device in step 2 includes a data concentrator, which is responsible for receiving data sent by multiple wireless temperature collectors within its monitoring area.

[0025] Preferably, the wireless transmitting unit adopts 433M wireless radio frequency technology for data transmission, and the LoRa protocol is used for communication between the wireless transmitting unit and the data concentrator; the communication module of the wireless receiving device adopts a 4G / 5G module to transmit data to the cloud server.

[0026] Preferably, after receiving the raw data, the intelligent monitoring background performs preliminary cleaning and formatting on the raw data, removes abnormal values, and uses timestamps to arrange the data in order to track the temperature change trend over time. The intelligent monitoring background adopts distributed database technology to persistently store the clear and formatted data.

[0027] Preferably, the wireless receiving device is powered by solar energy and batteries.

[0028] Preferably, the implementation method of performing preliminary cleaning on the original data includes:

[0029] Check data integrity: Perform integrity checks on the raw data received and remove data records with missing key fields, including temperature values, device identification, or timestamps;

[0030] Eliminate outliers: Set a reasonable temperature range, mark data records outside this range as outliers and eliminate them;

[0031] De-duplicate: Identify and remove duplicate data records.

[0032] Preferably, the implementation method of formatting the original data includes:

[0033] Timestamp formatting: convert the timestamps in the original data into a standard time format;

[0034] Data type conversion: Convert the temperature value to a floating point type and the device identifier to a string type.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The passive wireless temperature collector designed and manufactured can monitor the temperature of key areas of the railway contact network in real time. When the temperature data exceeds the set warning threshold, the system can immediately trigger the warning mechanism, realizing real-time monitoring and warning of the temperature of key areas of the contact network, greatly improving the safety of railway operations, avoiding equipment failures or operational accidents caused by excessive temperature, thereby improving the operating efficiency of the railway, and reducing the frequency and intensity of manual inspections, thereby reducing the cost of railway operation and maintenance.

[0037] The temperature collector is equipped with a high-precision temperature sensor that can accurately measure the temperature of key areas, avoiding the measurement errors caused by environmental factors in traditional temperature measurement methods, and providing more accurate and reliable temperature data for railway operations. The temperature collector obtains energy from the AC magnetic field of the overhead line feeder through electromagnetic induction technology, achieving self-power supply and avoiding the wiring difficulties and power supply problems in traditional wired temperature measurement methods.

[0038] Through the supporting wireless receiving equipment and cloud server architecture, temperature data can be remotely transmitted to the cloud platform for storage and processing. Users can view temperature information and receive early warning notifications in real time through terminal devices, realizing remote monitoring and intelligent management of data. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A diagram showing the processing steps of the method of the present invention;

[0040] Figure 2 This is a schematic diagram of the CT power supply operation;

[0041] Figure 3 It is the magnetization curve of the iron core;

[0042] Figure 4 It is the working characteristic diagram of the iron core coil;

[0043] Figure 5 This is the physical model diagram of the induction coil. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] See also Figure 1-5 The present invention provides a technical solution: a method for measuring the temperature of a key area of ​​a railway contact network, the specific steps of the method comprising:

[0046] Step 1: Design and manufacture a passive wireless temperature collector, the size of which meets the requirements of the contact network equipment clamp and has the functions of self-power supply, high-precision temperature measurement and wireless data transmission; the temperature collector includes a temperature sensing unit, an energy collection unit, a wireless transmission unit and an energy storage unit;

[0047] The temperature sensing unit includes a temperature sensor for real-time temperature collection of the key area, and the temperature sensing unit converts the analog signal sent by the temperature sensor into a temperature value through calculation; the energy collection unit uses electromagnetic induction technology to obtain energy from the AC magnetic field of the contact network feeder to provide power input for the temperature collector; the wireless transmission unit is responsible for transmitting the data collected by the temperature sensor to the outside; the energy storage unit is used to obtain and store excess energy from the energy collection unit for use in high-power consumption operations;

[0048] Step 2: Develop a wireless receiving device that is compatible with the temperature collector. The device is used to receive the temperature data wirelessly transmitted by the temperature collector, and a communication module is installed inside the wireless receiving device. The communication module is used to remotely forward the received temperature data to the cloud server.

[0049] Step 3: Build a server architecture for data reception, storage and processing on the cloud platform, and establish an intelligent monitoring background to analyze the temperature data sent by the temperature collector;

[0050] Step 4: Set the warning thresholds for temperature difference, temperature rise and instantaneous temperature rise in the intelligent monitoring background. When the monitored temperature data exceeds the set warning threshold, the warning mechanism is triggered;

[0051] Step 5: Install the passive wireless temperature collector described in step 1 in the key area of ​​the railway contact network, collect temperature data of the key area of ​​the contact network in real time through the temperature collector, and send the data to the wireless receiving device described in step 2 through wireless transmission. The wireless receiving device further forwards the data to the cloud server for storage and analysis. Users can view temperature information and receive early warning notifications in real time through terminal devices.

[0052] The temperature sensing unit adopts the temperature measurement methods including temperature measurement by thermochromic material, temperature measurement by thermocouple, temperature measurement by thermistor, temperature measurement by optical fiber, temperature measurement by digital sensor and temperature measurement by surface acoustic wave.

[0053] The present invention is further described below with reference to Examples 1 to 3:

[0054] Embodiment 1:

[0055] At present, the application of temperature sensors is almost everywhere in all fields. Common ones include thermocouple sensors, resistance temperature sensors, semiconductor temperature sensors, etc. The temperature sensors commonly used in existing models are platinum resistance, thermistor, thermocouple, and semiconductor sensor. These four sensors have their own shortcomings. A comparative analysis was carried out from the aspects of temperature measurement accuracy, measurement circuit complexity, anti-interference ability, and temperature measurement range.

[0056] As the core component of the HC168-A sensor, the thermistor has the characteristics of high sensitivity, fast response speed, and low cost, and is particularly suitable for real-time temperature monitoring. At the same time, the resistance value of the thermistor changes with temperature. The analysis of the HC168-A high-altitude outdoor passive wireless temperature sensor shows that the thermistor sensor with low measurement circuit complexity and strong anti-interference ability is the best. The sensor circuit is simple and reliable, meeting the research requirements. In summary, the HC168-A high-altitude outdoor temperature sensor is selected in the present invention.

[0057] Embodiment 2:

[0058] The energy harvesting unit uses the principle of electromagnetic induction to obtain energy from the AC magnetic field of the contact network feeder. By designing an induction coil inside the sensor, when the coil is in the AC electromagnetic field, an induced electromotive force will be generated, which will then be converted into electrical energy for the sensor to use.

[0059] Inductive power extraction utilizes the principle of electromagnetic induction and relies on a special current transformer (CT) to induce AC voltage from the high-voltage bus. After passing through impact protection circuits, energy discharge circuits, rectification, filtering, DC-DC conversion (Direct Current–Direct Current Converter, DC-DC) and other circuits, the low-voltage DC power supply required by the monitoring equipment can be obtained from the high-voltage bus.

[0060] See attached Figure 2, using active current transformer (induction coil) as induction power supply to achieve uninterrupted power supply is a basic requirement. When the bus current is small, it can still ensure the normal supply of power; when the bus exceeds the rated current, or even in extreme cases, when a short-circuit fault current occurs, it can protect the power board and not damage the device. In order to meet such requirements, the parameter design of the current transformer is particularly critical. The current transformer is composed of an iron core and a coil. The selection of the iron core and the design of the number of turns of the coil are the core and key of the induction power supply design. The minimum current that can induce a voltage in the induction coil is called the starting current. When the bus does not reach the threshold of the starting current, the power supply cannot work normally. At this time, the area below the starting current is the power dead zone. Therefore, in the design of the current transformer, it is necessary to minimize the power dead zone.

[0061] The electric energy obtained from the line through the current transformer is in the form of AC voltage, which cannot be used directly by the monitoring equipment. It must be converted into a standard DC voltage to power the monitoring equipment. Therefore, the induced electric energy must also be converted into DC and stabilized.

[0062] The current transformer energy-drawing method is convenient and direct for powering monitoring equipment, which has great advantages over other power supply methods. However, the limitations of the material properties of the energy-drawing device itself and the fluctuation of the line current will affect the induced voltage amplitude and the anti-saturation characteristics of the iron core of the energy-drawing device. For the inductive energy-drawing power supply method, there are still the following problems that need to be solved:

[0063] a) The bus current can still meet the power supply needs of the monitoring equipment under a wide range of changes.

[0064] b) Core structure design and parameter design of energy extraction coil.

[0065] c) When the bus current is large, the core material will cause magnetic saturation of the core, which will cause the induced voltage to be distorted.

[0066] The inductive energy harvesting device is responsible for supplying power to the online monitoring device end of the contact line clamp temperature, and is a key component of the monitoring device terminal. In order to meet the power supply problem at the monitoring device end, it is necessary to optimize the design of the energy harvesting coil and the power harvesting circuit to address the above problems. This is the key research content of inductive energy harvesting.

[0067] Especially when the bus current is at a high level in most cases, it is necessary to ensure that the core is still working in the critical saturation zone, or to effectively suppress the saturation of the core. In order to improve the performance of the core against magnetic saturation, it is an effective method to design the core with an air gap. The design of introducing an air gap in the core can improve the anti-saturation effect of the core, and at the same time enhance the core's ability to remove residual magnetism, which can greatly improve the performance of the induction coil.

[0068] The core of a traditional CT is generally a closed structure, and the closed-loop core structure is prone to magnetic saturation under large currents, which is a drawback that the induction power supply needs to overcome. In this design, an open air gap structure is used to change the excitation characteristics of the core. Considering that the current in the contact network will be large, the core is prone to magnetic saturation, so the open air gap structure in the core design can effectively suppress the magnetic saturation of the core.

[0069] The magnetization curve of the core magnetic material is shown in the attached figure. Figure 3 As shown, the horizontal axis represents the magnetic field intensity (H) and the vertical axis represents the magnetic flux density (B).

[0070] The magnetization curve can be viewed as two broken line regions, the linear region and the magnetic saturation region. In the linear region, the magnetic flux density increases with the increase of the magnetic field strength, which can be approximately regarded as a proportional relationship. When H reaches the saturation magnetic field strength H m1 , H m2 After that, H continues to increase, while B remains almost at B m The position remains unchanged, that is, the core enters the magnetic saturation state. After the air gap is introduced into the core, the residual magnetism of the core with air gap design is smaller than that of the core with closed loop structure, which makes it more difficult to enter the saturation state under the same bus current.

[0071] The characteristics of the core material itself will affect the characteristics of the power supply, but at the same time, the saturation state of the core is also related to external factors. Under normal circumstances, the core works in the linear region, that is, it is in an unsaturated state, and the primary bus current can stably output a specific voltage value through the coil. When the bus current reaches a certain level, the core will enter a saturated state. At this time, the size of the core magnetic flux does not change much. In this case, it is actually a protective effect on the power supply, which can suppress the power output of the current transformer under large bus current conditions. If the bus current continues to increase, the core will enter a state of deep saturation. At this time, the induced voltage waveform will be distorted, and a pulse voltage will appear. This pulse voltage is harmful, so certain methods are needed to suppress the core from entering a deep saturation state. The working characteristics diagram of the core coil is shown in the attached figure. Figure 4 shown.

[0072] When the bus current I 11 When the iron core has not yet reached the magnetic saturation state, the iron core is still in the linear change range, and the induced electromotive force E 21 The curve shows a regular waveform. When the current value increases to I 12 When the core is in saturation state, the magnetic flux in the core changes slowly. When the bus current is near the zero point, the magnetic flux in the core changes quickly, and the induced voltage E shown in the figure is 22 The curve increases accordingly. As the current continues to increase, the induced voltage waveform will have a peak and a large voltage amplitude, which is harmful to the back-end circuit.

[0073] When the core coil is magnetically saturated, the integral result of the induced voltage in half a cycle is a constant. The size of this constant has nothing to do with the bus current, but is only related to the saturation magnetic induction intensity, the core cross-sectional area and the number of turns on the secondary side of the coil. When the core is saturated, the mean value of the induced voltage in half a cycle is constant, so the induced voltage waveform becomes narrower, the induced voltage waveform is distorted, and the voltage has an obvious peak. When the core is deeply saturated, it will cause temperature rise, which can easily damage the induction coil. Therefore, the coil using induction power should ensure that the core works in the linear range as much as possible.

[0074] When the primary current varies widely, it is critical to select the appropriate induction coil core material. The selection of core material mainly focuses on the following parameters:

[0075] a) The saturation magnetic induction intensity should be high. This can avoid core saturation, reduce core heating, and avoid spike voltage.

[0076] b) The magnetic permeability should be high. The magnetic permeability of the core material determines the magnetic induction intensity of the induction coil. Materials with high magnetic permeability can induce higher voltages under the same magnetic field strength. This helps to reduce the starting current of the induction coil.

[0077] c) Small coercive force. The heat generated by hysteresis loss is related to the coercive force of the core material. The smaller the coercive force, the less heat is generated.

[0078] d) High resistivity: The iron core with high resistivity can reduce the energy consumption caused by induced current.

[0079] The commonly used core materials available are Permalloy, Nanocrystalline and Silicon Steel. The following table lists the typical parameters of the three core materials Permalloy, Nanocrystalline and Silicon Steel.

[0080]

[0081] Permalloy is an iron-nickel alloy whose magnetic properties can be controlled by corresponding processing technology, and its initial magnetic permeability and maximum magnetic permeability are relatively high. However, the disadvantages of Permalloy are also obvious. The saturation magnetic induction intensity is very low, and a slightly larger current will easily cause magnetic saturation of the iron core, causing the iron core to heat up, and the price of Permalloy is relatively expensive.

[0082] Silicon steel is a relatively traditional soft magnetic alloy with a low carbon content. Although the saturation magnetic induction intensity of silicon steel is relatively large, the initial magnetic permeability is relatively low.

[0083] Nanocrystalline materials have high saturation magnetic induction intensity, high magnetic permeability, low loss, and small coercive force, and can work stably for a long time at -55 to 130°C.

[0084] In the power-taking CT, the core material determines the magnetic permeability and saturation magnetic induction intensity of the coil. In order to reduce the minimum starting current of the normal power supply of the induction power supply device and reduce the power supply dead zone, the core material with high magnetic permeability should be selected. In order to prevent the core from entering the saturation state under high current conditions, materials that are not prone to magnetic saturation and materials with high saturation magnetic induction intensity should be selected. Taking the above factors into consideration, nanocrystalline materials are selected as the core material of the induction coil.

[0085] The induction coil is composed of an iron core and an enameled wire winding around the iron core. The primary side of the induction coil is the AC bus current, and the number of turns on the primary side is usually 1. The number of turns on the secondary side needs to be calculated and determined according to the design requirements. The physical model of the induction coil is shown in the attached figure. Figure 5 shown.

[0086] In order to make full use of the magnetic flux of the busbar annular distribution, combined with the actual installation and use, the iron core is designed in an annular shape, consisting of two semicircular iron cores, which can be opened and closed. The specifications of the iron core are as follows: outer diameter D = 60mm, inner diameter d = 40mm, width W = 10mm, from which it can be calculated that the cross-sectional area of ​​the iron core is 0.7cm 2 .

[0087] The saturation magnetic induction intensity of nanocrystal is B = 1.25T. In order to make the induced power supply meet the normal operation of the subsequent DC-DC regulated power supply, the minimum input voltage of the DC-DC module is 18V. Therefore, the secondary induced electromotive force is guaranteed to be at least 18V in the design. The bus power supply current frequency f = 50Hz, B = 1.25T, E = 18V, 2S = 0.7cm, λ = 0.7, and the theoretical value of the number of coil turns can be obtained as 1327 turns. In practice, considering the copper loss and leakage inductance, the number of turns with a 5% margin is increased as compensation, and then adjusted through specific experiments. In practice, enameled wire is selected to be wound on the iron core with 1420 turns.

[0088] Embodiment 3:

[0089] The system for realizing the above-mentioned temperature measurement method for key areas of railway contact network mainly includes a temperature monitoring unit, a data receiving unit and an intelligent monitoring background. The temperature monitoring unit is placed on the contact network and is responsible for collecting the temperature of the electrical nodes of the main conductive circuit, the temperature of the conductor connected to the electrical node and the ambient temperature, and sends the collected temperature data to the data receiving unit in a specific transmission format; the data receiving unit packages the temperature data received from different nodes and sends it to the intelligent monitoring background.

[0090] The temperature acquisition unit is directly installed on the key connection points of the traction power supply contact network (such as the low-voltage side terminals of the main transformer, the terminals of the disconnector, various electrical connection clamps, etc.) to sense and upload the temperature of the monitored point. The temperature acquisition unit consists of four parts: temperature sensing element, single-chip control circuit, short-range wireless communication module, and high-energy battery. The single-chip control circuit is responsible for collecting the temperature signal output by the temperature sensing element. When the temperature changes, it immediately controls the wireless communication module to send data to the outside. In order to reduce power consumption, the control circuit generally works in low-power mode and can automatically wake up and work at regular intervals. The wireless communication module is responsible for sending data to the outside, and the sent data includes the collected temperature, battery voltage, temperature sensing element status and other information. In the absence of obstruction, the wireless communication distance is more than 500m.

[0091] The data concentrator is responsible for receiving data sent by multiple wireless temperature acquisition units in its monitoring area, storing and processing them on-site, and can also exchange data with the central data processing system.

[0092] The data concentrator includes: acquisition unit communication module, remote communication module, MCU control processing module, power supply module and other components.

[0093] Using the acquisition unit communication module, a data concentrator can collect data sent by multiple wireless temperature acquisition units. This system is designed to manage up to 100 temperature acquisition units. The wireless communication distance between the temperature acquisition unit and the data concentrator can reach more than 500 meters. In other words, a data concentrator can receive temperature data from 100 monitoring points within a radius of 500 meters with it as the center.

[0094] According to the distribution statistics of the grid connection points of traction substations, only one data concentrator needs to be installed in a substation; in the future, if it is promoted at contact network connection points such as stations, it will be necessary to install a data concentrator at each end of the station.

[0095] The remote communication module is responsible for transmitting the collected monitoring data from the field to the remote monitoring center. The communication methods that can be used are: RS485 field bus method, RJ45 optical cable Ethernet method, or GPRS / CDMA wireless data communication method. The supported communication protocols can be: MODBUS, TCP, UDP.

[0096] In this project, the communication between the sensor and the wireless receiving device adopts 433M wireless radio frequency communication; the wireless receiving device transmits the data to the background monitoring system through the 4G / 5G module. The user only needs to log in to the specified IP address on the device that can be connected to the Internet (computer, mobile phone, iPad, etc.) to pay attention to the real-time temperature changes of each temperature measurement node. The temperature difference setting temperature is 15 degrees, the temperature rise setting temperature is 18 degrees, and the instantaneous temperature rise in one minute is set to 10 degrees. If this limit is exceeded, the associated computer and mobile phone will receive an alarm message.

[0097] The functions of the intelligent monitoring background are mainly composed of data receiving and processing center, data storage and management, data storage and management, statistical reports and visualization, and notification and response system.

[0098] 1) Data receiving and processing center

[0099] Data receiving module: This module is responsible for receiving temperature data sent from various wireless sensors, performing preliminary screening and decoding of the data, and ensuring the integrity and accuracy of the data.

[0100] Data preprocessing: Perform preliminary cleaning and formatting of the raw data to remove outliers and provide a reliable data basis for subsequent analysis. At the same time, use timestamps to arrange the data in order to facilitate tracking the temperature change trend over time. The implementation methods for preliminary cleaning of raw data include:

[0101] Check data integrity: Perform integrity checks on the raw data received and remove data records with missing key fields, including temperature values, device identification, or timestamps.

[0102] Eliminate outliers: Set a reasonable temperature value range, mark data records outside this range as outliers and eliminate them.

[0103] De-duplicate: Identify and remove duplicate data records.

[0104] The implementation methods for formatting raw data include:

[0105] Timestamp formatting: Convert the timestamps in the original data into a standard time format.

[0106] Data type conversion: Convert the temperature value to a floating point type and the device identifier to a string type.

[0107] 2) Data storage and management

[0108] Database system: Distributed database technology is used to ensure efficient storage and fast retrieval of massive data. The database design should support fast insertion of real-time data, long-term preservation of historical data, and efficient query performance.

[0109] Data backup and recovery: Implement regular data backup strategies to ensure data security. Design data recovery mechanisms to quickly restore services in the event of data loss or system failure.

[0110] 3) Analysis and early warning module

[0111] Real-time monitoring interface: Develop an intuitive operation interface to display the current temperature, historical temperature curves and warning status of all monitoring points, so that operation and maintenance personnel can see it at a glance.

[0112] Warning logic customization: Provides warning rule configuration function, allowing users to customize warning thresholds and alarm levels according to actual needs, increasing the flexibility and adaptability of the system.

[0113] 4) Statistical reports and visualization

[0114] Automatic report generation: The system should be able to generate temperature statistical reports for annual, monthly, daily and other periods as needed, including key indicators such as average temperature, maximum value, temperature rise rate, etc., and support downloading in PDF, Excel and other formats.

[0115] Visual display: Use graphical tools such as charts and dashboards to intuitively display temperature distribution, change trends, warning conditions, etc., to facilitate quick decision-making by management.

[0116] 5) Notification and response system

[0117] Instant SMS reminder: Integrate SMS service API, when the system detects temperature anomalies or reaches warning conditions, it automatically sends SMS reminders to preset maintenance personnel.

[0118] Mobile application notifications: Develop a supporting mobile APP that, in addition to receiving early warning notifications, also supports functions such as remote data viewing, receiving alarm details, and confirming processing status to improve response speed.

[0119] The wireless temperature measurement terminal can send temperature data to the communication unit receiving module through the 4G / 5G module. The communication receiving module can receive data sent by multiple temperature measurement terminals and send the data to the intelligent control unit through the serial port line; the control unit realizes temperature information data comparison, trend analysis, abnormal alarm, linkage line tripping, query and recording, etc.; the display unit displays the data, and can also display it intuitively in the form of curves and tables.

[0120] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0121] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring temperature in key areas of a railway contact network, characterized in that: The method specifically comprises the following steps: Step 1: Design and manufacture a passive wireless temperature collector, the size of which meets the requirements of the contact network equipment clamp and has the functions of self-power supply, high-precision temperature measurement and wireless data transmission; the temperature collector includes a temperature sensing unit, an energy collection unit, a wireless transmission unit and an energy storage unit; The temperature sensing unit includes a temperature sensor for real-time temperature collection of the key area, and the temperature sensing unit converts the analog signal sent by the temperature sensor into a temperature value through calculation; the energy collection unit uses electromagnetic induction technology to obtain energy from the AC magnetic field of the contact network feeder to provide power input for the temperature collector; the wireless transmission unit is responsible for transmitting the data collected by the temperature sensor to the outside; the energy storage unit is used to obtain and store excess energy from the energy collection unit for use in high-power consumption operations; Step 2: Develop a wireless receiving device that is compatible with the temperature collector. The device is used to receive the temperature data wirelessly transmitted by the temperature collector, and a communication module is installed inside the wireless receiving device. The communication module is used to remotely forward the received temperature data to the cloud server. Step 3: Build a server architecture for data reception, storage and processing on the cloud platform, and establish an intelligent monitoring background to analyze the temperature data sent by the temperature collector; Step 4: Set the warning thresholds for temperature difference, temperature rise and instantaneous temperature rise in the intelligent monitoring background. When the monitored temperature data exceeds the set warning threshold, the warning mechanism is triggered; Step 5: Install the passive wireless temperature collector described in step 1 in the key area of ​​the railway contact network, collect temperature data of the key area of ​​the contact network in real time through the temperature collector, and send the data to the wireless receiving device described in step 2 through wireless transmission. The wireless receiving device further forwards the data to the cloud server for storage and analysis. Users can view temperature information and receive early warning notifications in real time through terminal devices.

2. A method for measuring temperature in key areas of a railway contact network according to claim 1, characterized in that: The temperature sensing unit adopts the temperature measurement methods including temperature measurement by thermochromic material, temperature measurement by thermocouple, temperature measurement by thermistor, temperature measurement by optical fiber, temperature measurement by digital sensor and temperature measurement by surface acoustic wave.

3. A method for measuring temperature in key areas of a railway contact network according to claim 2, characterized in that: The energy collection unit relies on a current transformer to induce an AC voltage from a high-voltage bus, and obtains a low-voltage DC power supply required by the temperature collector from the high-voltage bus through an impact protection circuit, an energy discharge circuit, a rectifier circuit, a filter circuit and a DC-DC conversion circuit.

4. A method for measuring temperature in key areas of a railway contact network according to claim 3, characterized in that: The energy harvesting unit selects nanocrystalline material as the core material of the induction coil.

5. A method for measuring temperature in key areas of a railway contact network according to claim 4, characterized in that: The wireless receiving device in step 2 includes a data concentrator, which is responsible for receiving data sent by multiple wireless temperature collectors in its monitoring area.

6. A method for measuring temperature in key areas of a railway contact network according to claim 5, characterized in that: The wireless transmitting unit adopts 433M wireless radio frequency technology for data transmission, and the LoRa protocol is used for communication between the wireless transmitting unit and the data concentrator; the communication module of the wireless receiving device adopts a 4G / 5G module to transmit data to the cloud server.

7. A method for measuring temperature in key areas of a railway contact network according to claim 6, characterized in that: After receiving the raw data, the intelligent monitoring background performs preliminary cleaning and formatting on the raw data, removes abnormal values, and uses timestamps to arrange the data in order to track the temperature change trend over time. The intelligent monitoring background adopts distributed database technology to persistently store the clear and formatted data.

8. A method for measuring temperature in key areas of a railway contact network according to claim 7, characterized in that: The wireless receiving device is powered by solar energy and batteries.

9. A railway contact network key area temperature measurement method according to claim 7, characterized in that: The implementation methods of preliminary cleaning of raw data include: Check data integrity: Perform integrity checks on the raw data received and remove data records with missing key fields, including temperature values, device identification, or timestamps; Eliminate outliers: Set a reasonable temperature range, mark data records outside this range as outliers and eliminate them; De-duplicate: Identify and remove duplicate data records.

10. A railway contact network key area temperature measurement method according to claim 7, characterized in that: The implementation methods for formatting raw data include: Timestamp formatting: convert the timestamps in the original data into a standard time format; Data type conversion: Convert the temperature value to a floating point type and the device identifier to a string type.

Images