CN105698962A - Teletransmission resonance-type SAW (surface acoustic wave) temperature sensing device used for high-voltage equipment - Google Patents

Abstract

The invention provides a remote transmission resonant SAW temperature sensing device for high-voltage equipment, including a surface acoustic wave sensing unit and a remote transmission unit, wherein the surface acoustic wave sensing unit is a dual-port structure, including an input and output switch The energy device and two reflective grids that constitute the acoustic resonator. The remote transmission unit includes a directional gain antenna, an omnidirectional rotating antenna and a signal collector. The directional gain antenna is a helical arm dipole antenna. Connected, it can play the role of transmitting query pulses and receiving feedback pulses carrying temperature signals, thereby reducing the difficulty of adjusting the directional alignment between antennas in engineering. The invention can effectively overcome the characteristics of poor orientation and short transmission distance of the existing SAW temperature sensing device, and can be widely applied to various high-voltage power equipment that is not convenient for manual temperature collection, and can effectively improve the reliability and reliability of power grid operation. Safety provides an effective guarantee for the real realization of unattended operation.

Description

A remote resonant SAW temperature sensing device for high voltage equipment

technical field

The invention relates to the technical field of temperature sensing devices, in particular to a remote-transmission resonant SAW temperature sensing device for high-voltage equipment.

Background technique

In recent years, with the advancement of technology, the high-voltage power system has introduced various advanced temperature testing equipment, including temperature measurement wax sheet, optical fiber temperature measurement, infrared temperature measurement and active wireless temperature measurement, etc. However, these four schemes There are various hidden dangers and shortcomings. Although the passive wireless temperature solution based on SAW was mentioned as early as the 1980s, it has not been applied in actual engineering because of its short temperature measurement distance.

The utility model with the application number 201120379839.2 relates to sensor testing technology, specifically a resonant SAW temperature sensor automatic test system, the difference is that the system includes a computer, a network analyzer, a SAW sensor temperature test platform, and a SAW sensor temperature test platform Including test fixture, test circuit and external port, matching circuit, air gun; test circuit includes wireless read-write device, MCU measurement and control module, the wireless read-write device is equipped with a first antenna, and the test fixture is composed of a test chip table and an automatic tablet pressing mechanism ; The test chip platform is equipped with a SAW antenna interface, and the SAW antenna interface is equipped with a second antenna that communicates wirelessly with the first antenna; the external ports of the SAW sensor temperature test platform are respectively connected to the network analyzer and the computer through signal lines. Connection, the network analyzer is interconnected with the computer. The utility model has the function of measuring the inherent parameters of the SAW temperature sensor chip at room temperature and the dynamic parameters of the SAW temperature sensor chip at changing temperatures.

At the same time, a large number of on-line monitoring sensor devices are distributed and applied, and their power supply technology has great limitations. If battery power is used, the battery itself has potential safety hazards in high-voltage and strong electromagnetic environments; Under the premise of supply, the real-time performance of data is poor; the maintenance cost of regular replacement is huge; if CT induction power is used, the induction power collection device is large in size and difficult to install in a small space; the installation process is cumbersome and the time period is long; the busbar The real-time change of current causes shock and damage to the power supply system. At the same time, the complex electromagnetic interference of the substation will directly lead to abnormal operation of the circuit. The temperature measuring device is easy to wear and tear, and the safety and reliability are low.

Contents of the invention

The technical problem to be solved by the present invention is to provide a remote resonant SAW temperature sensing device for high-voltage equipment, which solves the disadvantages of poor stability and accuracy of traditional temperature sensors, and has high power supply security and reliability.

In order to solve the above technical problems, the present invention adopts the following technical solutions: a remote resonant SAW temperature sensing device for high-voltage equipment, including a power supply device, a sensing unit connected to it, and a remote transmission unit; The source device is composed of an inductive energy harvesting device, a rectification and voltage stabilization unit, and a battery; the sensing unit is a single-port structure, including an input and output transducer and two reflective grids forming an acoustic resonant cavity; the remote transmission unit includes Directional gain antenna, omnidirectional rotating antenna and signal collector.

The induction energy harvesting device is an electric field energy collection device, including a flat plate capacitor, and the flat plate capacitor is placed in an alternating electric field.

The rectification and voltage stabilization unit integrates a rectifier and a step-down converter.

The directional gain antenna is a helical arm dipole antenna connected to the signal collector through a coaxial cable

The signal collector is connected to a data processing unit, the data processing unit includes a DSP chip, and the data processing unit converts the signal collected by the sensing unit into a digital signal.

The electric field energy collection device collects high-voltage line coupling energy generated in the environment and converts it into electric energy, which is rectified and stabilized by the rectifying and stabilizing unit and stored in the battery to supply power for the sensing unit.

The present invention adopts the above-mentioned technical scheme. First, the sensor is based on surface acoustic wave technology, and its main components are input and output transducers and two reflective grids forming an acoustic resonant cavity. The quality and life of the device lead to the problem of low reliability of the device. Its service life can be the same as the monitored equipment. It not only ensures that the online monitoring device can continuously and stably monitor the state of the main equipment, but also avoids adverse effects on the operation and maintenance of the main equipment due to the reliability of the online monitoring device. Because this type of surface acoustic wave sensor realizes passive wireless data acquisition and transmission, it does not need to use batteries, and does not need to connect cables between high and low potentials, so it has extremely high safety and is very suitable for high-voltage, strong electromagnetic Working in the environment, especially the temperature sensor based on the surface acoustic wave principle, fills the gap in the field of monitoring the state parameters of the existing equipment. The core of the input and output transducer is the interdigital transducer, which is an acoustic-electric transducer that excites and detects surface acoustic waves (SAW) on piezoelectric crystals. On the electrical substrate, the metal film is carved into a structure of a specific size and shape by photolithography. The reflective grid of SAW is the key device to realize the SAW resonator. SAW is based on the array of reflective elements to form the SAW mirror. The SAW reflective grid has two types of reflective grooves and reflective metal strips. The performance of the groove reflective array is better. However, metal reflective grid arrays are the easiest to implement.

Secondly, applying the inductive energy harvesting technology to the sensing device, on the one hand, reduces the complexity and difficulty of the power supply, and can make rational use of resources; on the other hand, adding a rectifier, step-down The device, storage battery and voltage stabilizing circuit can effectively prevent the power supply circuit from being burned due to excess energy absorbed by the energy harvesting unit under high current, reduce the calorific value of the power supply, and effectively store the excess absorbed energy, and can avoid power transmission. When the line current is small current or the power is cut off, the power supply of the monitoring equipment is insufficient, so as to ensure that the energy harvesting power supply can output stable DC power to the monitoring equipment, and ensure the continuous and stable operation of the monitoring equipment; and it can prevent the energy harvesting unit from being saturated and make the power harvesting The energy unit can generate instantaneous high power, which enhances the load capacity and adaptability of the energy source.

In addition, in order to realize the stability and efficiency of long-distance transmission, the present invention uses two kinds of antennas in the long-distance transmission unit, that is, a directional gain antenna and an omnidirectional rotating antenna. The directional gain antenna is a helical arm dipole antenna, and the The signal collector is connected, which can play the role of transmitting query pulses and receiving feedback pulses carrying temperature signals, thereby reducing the difficulty of adjusting the directional alignment between antennas in engineering; the omnidirectional rotating antenna is omnidirectional in the normal direction The small helical antenna connected to the SAW sensor plays the role of receiving the query pulse and feeding back the SAW resonance signal to the transmitting antenna. The principle of configuring the antenna in this way is: the antenna connected to the signal collector sends query pulse signals to multiple SAW probes, and its installation position can be adjusted freely within the specified range, so it is a directional high-gain antenna; the antenna connected to the SAW probe The installation of the antenna position is determined by the position of the measured point. The installation direction may be relatively narrow and the query signal from the signal collector needs to be received in all directions. Therefore, the use of a normal omnidirectional small helical antenna reduces the engineering cost. Difficulty in adjusting directional alignment between antennas.

When this type of sensing device is applied to online monitoring technology, it can not only effectively promote the progress of substation intelligent status monitoring technology, thereby avoiding the traditional online monitoring device using a large number of electronic components, using batteries or CTs for power supply, There are technical defects in terms of security, reliability, and stability. The surface acoustic wave technology adopts a passive working mode, without the use of electronic components and any power supply device, and realizes a passive wireless state monitoring method, which effectively solves the problems of traditional online monitoring devices in terms of safety, reliability, stability, etc. Existing problems. At the same time, surface acoustic wave technology and inductive energy harvesting technology are conducive to realizing more and more comprehensive equipment condition monitoring content. These are undoubtedly great advances in condition monitoring technology. Moreover, it can save costs and improve the safe operation level of equipment. A remote resonant SAW temperature sensing device for high-voltage equipment has the same lifespan as the monitored equipment, and has extremely high reliability and stability; Energy harvesting technology replaces traditional solar energy and batteries, which greatly reduces the maintenance workload of the system and is conducive to saving costs. At the same time, the application of a remote resonant SAW temperature sensor device for high-voltage equipment not only ensures The reliability and stability of the online monitoring device is also conducive to the realization of some new monitoring of characteristic quantities that more truly reflect the operating status of the equipment, so as to grasp the status of the equipment more timely, accurately and comprehensively. Through real-time historical database technology, various online monitoring data, PMS, and SCADA system data are integrated on a unified data platform to assist in the realization of advanced applications such as equipment status diagnosis and power grid equipment operation status analysis. In summary, the present invention can effectively overcome the characteristics of poor orientation and short transmission distance of existing SAW temperature sensing devices, and can be widely used in various high-voltage power equipment that is not convenient for manual temperature collection, and can effectively improve the reliability of power grid operation. Reliability and safety provide an effective guarantee for the real realization of unattended operation.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Fig. 1 is a structural principle diagram of the present invention;

Fig. 2 is the data amplification block diagram of data processing unit;

Figure 3 is a block diagram of battery charging and discharging.

detailed description

As shown in Figure 1, Figure 2, and Figure 3, a remote resonant SAW temperature sensing device for high-voltage equipment includes a power supply device, a sensing unit connected to it, and a remote transmission unit; the power supply device consists of Inductive energy harvesting device 1, rectification and voltage stabilization unit 2 and battery 3 are composed; sensing unit 6 is a single-port structure, including input and output transducer 7 and two reflective grids 8 forming an acoustic resonant cavity; remote transmission unit 9 includes Directional gain antenna 10, omnidirectional rotating antenna 11 and signal collector 12; induction energy harvesting device 1 is an electric field energy collection device, including a flat plate capacitor, which is placed in an alternating electric field; the rectifying and stabilizing unit integrates a rectifier 4 and a step-down converter 5; the directional gain antenna 10 is a helical arm dipole antenna, connected to the signal collector 12 through a coaxial cable 13; the signal collector 12 is connected to a data processing unit 13, and the data processing unit includes a DSP chip.

The data processing unit converts the signal collected by the sensing unit into a digital signal. The electric field energy collection device collects the high-voltage line coupling energy generated in the environment and converts it into electrical energy. unit powered. The induction energy harvesting device is an electric field energy collection device, which is placed in an alternating electric field with a flat plate capacitor, and the current and voltage are induced at both ends of it, and the electric field energy is converted into electric energy to supply power to the load; the rectification and voltage stabilization unit integrates a low Loss rectifiers and a high-efficiency step-down converter to couple energy by harvesting high-voltage equipment generated in the environment and then convert this energy into a well-regulated output to power sensors, data processing units, and external communication units; temperature The sensing unit is a sensor made based on the principle of surface acoustic wave; the data processing unit provides functions such as filtering, amplification, down-conversion, and transmission frequency control, and converts the signal collected by the sensor into a digital signal that can be directly processed by the acquisition controller; external communication The unit can complete the data communication function from the internal sensor of a single device to the acquisition controller, and realize the wireless safety isolation between the high and low potentials of the online monitoring device of the electric power equipment.

The core of the device lies in the measurement of the temperature sensor based on the surface acoustic wave. The SAW resonator is mainly divided into two structures: single-port and dual-port. , and acts as an output transducer. The two reflective grating arrays on the left and right of the IDT are symmetrically distributed to form an acoustic resonant cavity. The IDT introduces the energy of the excitation signal and extracts the energy in the resonant cavity. In SAW with the same frequency of electromagnetic waves, the sound wave is reflected back and forth multiple times in the resonant cavity composed of two reflection grids. When the frequency of the excitation signal matches the size of the acoustic resonant cavity, a standing wave is formed in the cavity and resonance is generated. The resonant frequency f ₀ directly reflects the measured information and is an important characteristic parameter of the SAW sensor, and its expression is as follows: ; Among them, V is the wave velocity of the surface acoustic wave excited on the surface of the _SAW substrate, and L is the reflection array period.

When the temperature of the piezoelectric substrate surface of the SAW resonator changes, the propagation velocity V _SAW of the SAW and the spacing L of the emission grid change, which causes the resonant frequency of the resonator to change, which can be reflected from the change of the resonant frequency The measured temperature information can monitor the temperature parameters by measuring the variation of the frequency. In engineering, the relationship between the resonant frequency of a SAW resonator and the temperature is generally expressed by a polynomial, and the general equation of its frequency-temperature characteristics is:

; where T is the measured temperature, T ₀ is the reference temperature, f ₀ is the resonance frequency at the reference temperature, a ₀ , b ₀ , c ₀ are the first-order, second-order and third-order at the reference temperature T ₀ Frequency and temperature parameters. These parameters are related to the selected crystal material and its cutting direction. Piezoelectric crystals use different materials and different tangential directions, and their temperature coefficients are different, as are the electromechanical coupling coefficients and dielectric losses.

The remote transmission unit in the present invention includes a directional gain antenna, an omnidirectional rotating antenna and a signal collector, the signal collector is connected to a data processing unit including a DSP chip, and the data processing unit converts the signal collected by the sensing unit into a digital signal. The antenna is an important tool for connecting the transmitting device and the receiving device in this scheme. Its basic function is to receive and radiate electromagnetic waves. In order to increase the wireless transmission distance in the embodiment, the gain and performance of the antenna are improved, and the transmission power and the transmission power of the transmitter are increased. Receiver sensitivity. This program works with the 429MHz to 436MHz public band. The country stipulates that the signal transmission power of this band shall not exceed 10mV. It is difficult to improve the sensitivity of the receiver after reaching a certain level. Therefore, designing a high-performance antenna can significantly improve the performance of the wireless sensor system. Therefore, for the most important parameters of the antenna: directivity and gain effect, this program develops two antennas according to the needs and characteristics of practical engineering applications, namely, the directional gain antenna and the omnidirectional rotating antenna. The directional gain antenna is a helical arm pair The pole antenna, connected to the signal collector through a coaxial cable, can play the role of transmitting query pulses and receiving feedback pulses carrying temperature signals, thereby reducing the difficulty of adjusting the directional alignment between antennas in engineering; omnidirectional rotation The antenna is an omnidirectional small helical antenna in the normal direction, which is connected with the SAW sensor to receive the query pulse and feed back the SAW resonance signal to the transmitting antenna. The principle of configuring the antenna in this way is: the antenna connected to the signal collector sends query pulse signals to multiple SAW probes, and its installation position can be adjusted freely within the specified range, so it is a directional high-gain antenna; the antenna connected to the SAW probe The installation of the antenna position is determined by the position of the measured point. The installation direction may be relatively narrow and the query signal from the signal collector needs to be received in all directions. Therefore, the use of a normal omnidirectional small helical antenna reduces the engineering cost. Difficulty in adjusting directional alignment between antennas.

The SAW sensor adopts a passive wireless data acquisition and transmission method, does not need to use batteries, and does not need to connect cables between high and low potentials, so it has extremely high safety and is very suitable for working in high voltage and strong electromagnetic environments. The adoption of the new high-voltage induction power harvesting technology has unique energy harvesting methods and design concepts, and has the characteristics of adapting to various bad weather, stable and reliable power supply all-weather, long-term maintenance-free operation, etc., thus overcoming the problems of solar power supply and traditional CT harvesting. It has become an excellent choice to solve the problem of energy supply for online equipment due to the various shortcomings of the power supply method.

In the specific implementation, the difficulty lies in the energy harvesting design of the sensor device, the design of power amplification, and the control design of battery charge and discharge; among them, because the energy harvesting of the device is achieved by integrating a low-loss rectifier and a high-efficiency step-down converter , to provide energy to the light-emitting element assembly by collecting high-voltage line coupling energy generated in the environment, and then converting this energy into a well-regulated output. The energy harvesting module is designed to directly rectify the voltage waveform and store the harvested energy in an external storage capacitor, while dissipating any excess power through an internal shunt regulator. An ultralow quiescent current undervoltage lockout mode with a wide hysteresis window allows charge to accumulate on the storage capacitor until the buck converter can efficiently transfer some of the stored charge to the output. During the no-load sleep state, the output voltage can be regulated while continuously charging the storage capacitor.

For power amplification design, the power amplifier is an important part in the data processing unit. Due to the small coupling energy, it cannot provide power directly. After the low-power signal is modulated and processed, due to the impedance characteristic, if it is directly connected to the coupling circuit, it will be attenuated quickly because the signal is too small. For this reason, it is necessary to use the existing technology to amplify the power of the small signal so that the entire communication process can go on smoothly. According to the actual situation, the technology of the power amplifier mainly realizes the following functions: there is enough output power to ensure the normal transmission of the signal in the coupling system and circuit transmission; the rated load impedance of the power amplifier is required to match the impedance of the coupling circuit; due to load changes Relatively large, the power amplifier circuit is required to have a strong load capacity; the power amplifier is required to work stably and have reliable performance; according to the characteristics of a typical OTL circuit, build an experimental circuit as shown in the figure. In this circuit, the front end is a voltage amplifier, the OTL circuit receives signals from the front end, and the back end is an output signal.

For the design of charge and discharge control, with the development of power electronic devices, the technology and manufacturing process of high-power switching devices such as insulated gate bipolar transistors IGBT are becoming more and more mature, and have been used in converters, active power filters, rectifiers, and inverters. , Dynamic voltage regulator and other aspects have been successfully applied. In this embodiment, a circuit composed of IGBTs is used to generate a high-power sinusoidal signal. After the signal is boosted by a step-up transformer and amplified by a high-voltage series resonant circuit, the voltage level can reach high-voltage, ultra-high voltage, and ultra-high voltage levels. The mathematical model of the frequency-modulated resonant UHV test power supply is established, and on this basis, a voltage regulation self-adjusting proportional-integral control method and a new PI phase-locked automatic frequency regulation method are proposed, so as to realize the regulation of the entire sensing device. Voltage and frequency modulation, the control method we proposed is beneficial to eliminate the steady-state error of the sensing device and improve the dynamic performance of the sensing device, and is easy to realize in engineering. Among them, the frequency control is mainly composed of three-phase uncontrollable rectifier circuit, H-bridge inverter circuit, an output filter, and a series resonant circuit.

Taking the sensor device applied to the temperature detection field of a 10KV substation as an example, it is applied to 10 switch cabinets in a 10KV high-voltage room, and six temperature sensing devices and wireless temperature measurement collectors are installed in each switch cabinet, of which , the temperature sensing device is installed at the contact point that is prone to heat, and the temperature signal is transmitted wirelessly to the wireless temperature measurement collector. Console server, the server completes the display, analysis, storage, recording, printing and alarm processing of the temperature data of each switch cabinet. When the temperature rise exceeds the set value, or the temperature rise rate is too fast, or the temperature difference between the three phases is unbalanced, the system will automatically alarm. In practical applications, it was found that the B-phase outlet line of the 4th side of the 10-sided switch cabinet was exposed to electric shock temperature It was as high as 75°C, but the junction temperature of phase A and phase C was only 52°C. The system judged that the temperature of phase B was abnormal based on the unbalanced temperature difference between the three phases. After inspection by the staff, it was found that phase B was due to the fastening bolts Loose, resulting in poor contact of the outlet contacts, excessive contact resistance, resulting in abnormal temperature rise, thus successfully eliminating potential safety hazards and preventing a possible safety accident.

Claims (5)

1. A remote transmission resonant type SAW temperature sensing device for high-voltage equipment, characterized in that: comprise a source device and a sensing unit connected thereto respectively, a remote transmission unit; the source device consists of an induction energy harvesting device , a rectifying and stabilizing unit and a battery; the sensing unit is a single-port structure, including an input and output transducer and two reflective grids forming an acoustic resonant cavity; the remote transmission unit includes a directional gain antenna, an omnidirectional rotating Antenna and signal collector. 2. The remote transmission resonant type SAW temperature sensing device for high-voltage equipment as claimed in claim 1, characterized in that: the induction energy harvesting device is an electric field energy collecting device, comprising a flat capacitor, and the flat capacitor is placed in an alternating electric field. 3. The remote resonant SAW temperature sensing device for high-voltage equipment according to claim 1, wherein the rectification and voltage stabilization unit integrates a rectifier and a step-down converter. 4. The remote transmission resonant type SAW temperature sensing device for high-voltage equipment as claimed in claim 1, wherein: the directional gain antenna is a helical arm dipole antenna, and is collected with the signal by a coaxial cable device connected The remote resonant SAW temperature sensor device for high-voltage equipment according to claim 1, wherein the signal collector is connected to a data processing unit, and the data processing unit includes a DSP chip, and the data processing unit The signal collected by the sensing unit is converted into a digital signal. 5. The remote transmission resonant SAW temperature sensing device for high-voltage equipment as claimed in claim 2, characterized in that: the electric field energy collection device collects the high-voltage line coupling energy generated in the environment and converts it into electrical energy. The rectifying and stabilizing unit rectifies and stabilizes the voltage and stores it in the storage battery to provide power for the sensing unit.