| In response to the call of smart grid,it is very important to realize real-time structural health monitoring(SHM)through current monitoring.(SHM)through current monitoring.Real-time monitoring of the operation of electrical equipment,accurate location of faults in advance,and remote monitoring through wireless sensor nodes have become A real-time hotspot.The early warning and accurate positioning of the location of the fault node can ensure the safe and reliable use of electricity and the efficient operation of electric equipment,and can avoid the economic loss and personal safety caused by the safety of electric accidents.It can be seen that the development and application of wireless current sensors have become crucial.Aiming at the field of wireless current detection,this paper mainly proposes a dual-frequency microstrip antenna cantilever beam single-phase current sensor for the continuous monitoring of single-phase AC current.The signal is transmitted wirelessly.On top of this,in order to improve the sensitivity and accuracy of this sensor,a secondary sensitivity amplification mechanism and a temperature self-compensation scheme are also proposed.The main elements are summarised as follows:In this paper,the dual-frequency microstrip antenna has two functions,which can be used for current sensing and signal transmission.The two basic elements of the single-phase AC current sensor are the cantilever beam and the dual-frequency microstrip antenna.The two-core current-carrying wire is energised and an induced magnetic field is generated around the wire.The permanent magnets attached to the free end of the cantilever beam are driven up and down by magnetic forces,and the cantilever beam is deformed and thus subjected to strain.Dual-frequency microstrip antenna It is pasted to the fixed end of the cantilever beam with super glue,and the strain is transmitted to the microstrip antenna through the cantilever beam,and the microstrip antenna is deformed by the strain.changes,so that its two resonant frequencies are offset.Therefore,the linear relationship between the current and the resonant frequency offset can be finally obtained through the permanent magnet magnetic force model,the cantilever beam free end steady-state displacement model,the cantilever beam fixed end strain model and the dual-frequency microstrip antenna resonant frequency offset model.Secondly,in order to increase the sensitivity and accuracy of the whole sensor,two sensitivity amplification mechanisms and a temperature self-compensation method are further proposed on the basis of its theoretical model.Among them,the first-order sensitivity amplification mechanism is realized by material reduction on the dielectric substrate of the microstrip antenna,the effective material reduction position on the microstrip antenna is explored,and the difference between the hole radius and hole spacing and the sensitivity is found by controlling the variable method.relationship;the secondary sensitivity amplification mechanism is realized by the dual-frequency differential of the microstrip antenna.In order to maximize the sensitivity of the sensor,we continue to explore the relationship between the primary sensitivity amplification mechanism and the secondary sensitivity amplification mechanism.The condition of the differential is to amplify the desired sensing parameters,and at the same time,to suppress the influence of external factors.Therefore,a temperature self-compensation scheme is proposed based on the dual frequency differential.In order to reduce the size of microstrip antennas and to implement the physical layer standard IEEE802.11 g,a dual-frequency coaxial microstrip antenna is designed through theoretical size design,size optimization,impedance matching and performance analysis,and its two center resonance frequencies are 2.45 GHz and5.2GHz.Then,the size of the cantilever beam is designed,and the design standard is to adapt it to the size of the dual-frequency coaxial microstrip antenna while realizing current sensing.Finally,the designed dual-frequency microstrip antenna cantilever beam singlephase AC current sensor is experimentally verified.Due to the limitations of the experimental equipment and experimental conditions,the experimental test platform was split into two parts,namely experiment A-current strain experiment and Experiment B-Strain Antenna Experiment.Strain is used as a pivot,an intermediate variable,The ultimate aim is to obtain a linear relationship between the current signal as input and the normalised resonant frequency of the microstrip antenna as output and to obtain a linear equation between the two.At the same time,the reliability of the dual frequency differential is experimentally verified.This paper mainly proposes a system integrating cantilever beam and microstrip antenna to realize continuous single-phase AC current monitoring conforming to the IEEE 802.1lg protocol standard,which provides new possibilities for the construction of wireless current sensing nodes. |
PDF Full Text Request