Research On High Precision Electrostatic Measurement Method Based On Fiber Fabry-Perot

With the accelerated construction of new power systems and the continuous improvement of the intelligence of power equipment,the decarbonization and digitalization of power equipment has become important future directions.As an effective means of signal monitoring for each node in the power system,the new passive optical fiber sensor is an effective assistance for the safe and stable operation of the power system.Among them,the accurate measurement of electrostatic voltage is of great significance to the operational state control and fault state feedback of the power grid.Therefore,the development of high-precision contactless optical fiber electrostatic sensors is the crucial for accurately evaluating the performance of power equipment.In this paper,a non-contact optical fiber Fabry-Perot（F-P）electrostatic sensor and its online measurement system were developed by using the transducer characteristics of electromechanical coupling components and the passive and anti-electromagnetic interference characteristics of optical sensing technology.In this paper,an optical fiber F-P electrostatic sensor was employed as the research object,and the research was carried out with the goal of improving the accuracy and stability of the optical fiber electrostatic sensing system.Firstly,an electromechanical coupling model at the sensitive end of the sensor was established,and the working principle of the non-contact optical fiber F-P electrostatic sensor was introduced and the F-P electrostatic sensor was fabricated based on the theoretical basis of electromechanical coupling effect and optical fiber communication.The displacement driving characteristics of the different electromechanical materials were tested,and the dynamic output characteristics of the sensors with different shapes and sizes of collector ends were tested.The results show that the sensor with a 5cm radius collector end has good linearity and sensitivity with a linear fit of R²=99.4%and a sensitivity of 53.1pm/k V.Secondly,based on the F-P interference principle fused with micro-optics,a non-contact optical fiber F-P electrostatic measurement system was built,non-contact online measurement experiments of electrostatic voltage were carried out.Sensor static characteristics and optical calibration experiments were conducted,and the sensor error analysis was conducted.The results show that the repeatability error of the sensor was 2.23%.Finally,an optical fiber F-P electrostatic sensor model based on the principles of solid mechanics and charge induction was established by using the method of COMSOL finite element simulation,and the influence of the structural parameters of the sensor components on the output characteristics of the sensor was investigated.The displacement driving characteristics of the sensitive end of the different materials,shapes and electrodes were simulated and analyzed.The results show that the PZT piezoelectric material with circular silver electrodes had a high displacement driving amount as the sensitive end of the sensor.The charge distribution of the sensing electrodes with different shapes and sizes of the collector ends were simulated,and the effect of edge effect on the charge distribution of the electrodes of the sensors was investigated.The results show that the collector end with a radius of 5cm had a high charge induction,and its maximum induced charge is 5.46×10^-9C.The charge distribution characteristics of the sensor at different voltages were studied,the induced potential difference at the front end of the sensor was calculated,and the displacement output characteristics of the sensor cavity under different induced potential differences were simulated.This paper presented a theoretical and experimental study of non-contact optical fiber F-P electrostatic sensors based on the optical interference principle.The influence of structural parameters of the sensitive end and the collector end on the output characteristics of the sensor was explored by combining experiments and simulations.This study promotes the application of optical electrostatic sensors on smart grids and provides solutions for non-contact optical electrostatic online monitoring in new power systems.