液体绝缘对光纤法布里-珀罗局放超声传感器特性参数影响

Impact of Liquid Insulation on Characteristic Parameters of Fiber Fabry-Perot Partial Discharge Induced Ultrasound Sensor

非本征光纤法布里-珀罗(F-P)传感器已被用于液-固复合绝缘局部放电检测,但存在液体黏滞阻尼和附加质量影响传感器固有频率和灵敏度的问题。采用有限元方法计算传感膜片在油和空气介质中受迫振动幅频响应,并分析不同温度下传感器幅频特性和灵敏度。提出F-P传感器的液体隔离结构,消除介质对其参数的影响。制备FP传感器并构建实验系统,测试不同温度下两种结构传感器的幅频特性。实验结果表明:液体绝缘油中,F-P传感器因黏滞阻尼和附加质量导致固有频率下降约0.58,幅频曲线带宽变大,响应幅值降低;液体介质温度升高,传感器固有频率增加,幅频曲线带宽变小,响应幅值增加,灵敏度变大;液体隔离结构的F-P传感器不受介质黏滞阻尼和附加质量影响。

Extrinsic fiber Fabry-Perot（F-P）sensor could detect partial discharge in liquid-solid composite insulation,but natural frequency and sensitivity of F-P sensor are affected by viscous damping and added mass of liquid insulation.We use finite element analysis method to simulate the amplitude-frequency response characteristics of F-P sensor under forced vibration in air and liquid insulation medium,and analyze the amplitude-frequency characteristics and sensitivity of F-P sensor at different temperatures.We propose the F-P sensor with isolating liquid insulation structure to eliminate the effect of medium and design an experiment system to measure amplitudefrequency response curves of F-P sensors at different temperatures.The experimental results show that due to viscous damping and added mass of liquid,natural frequency of F-P sensor in liquid insulation transformer oil is 0.58 times of that in air,the bandwidth of amplitude-frequency curve becomes wider,and the harmonic response amplitude decreases.Furthermore,the temperature of liquid medium increases,the natural frequency of F-P sensor increases,the bandwidth of amplitude-frequency becomes narrower,and the harmonic response amplitude and sensitivity increase.It＇s found that F-P sensor with isolating liquid insulation structure are immune to media viscous damping and additional mass.