An Efficient Self-Powered Method for Power Transformers Vibration Monitoring Sensors Based on the Sm-Doped-PMN-PT Piezoelectric Bimorph Array

To realize passive vibration monitoring of power transformers, this study proposes a self-powered method for transformer vibration monitoring sensors based on the Sm-doped-Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) piezoelectric bimorph array. This study conducts the theoretical analysis and field measurement of the transformer vibration signals. In addition, the preparation method of a high-performance Sm-doped-PMN-PT piezoelectric bimorph is investigated. The properties of the xSm-PMN-yPT ceramics are also analyzed. Further, the output voltage and power characteristics of the piezoelectric bimorph arrays with different combinations are compared. Finally, the validation and application of the prototype are presented. The experimental results show that the 2.5%Sm-PMN-32PT has a high piezoelectric coefficient (d(33)) of 1710 pC/N. The results also indicate that the piezoelectric self-powered device with a parallel structure consisting of nine piezoelectric bimorphs has a maximum power generation of 2.341 mW under the measured transformer vibration excitation. Moreover, it is shown that it takes 75 min to complete the charging of the 7.5 V-1-F faradic capacitor from 4.4 to 5 V to satisfy the condition for the required energy of 2.82 J for the vibration signal acquisition, processing, and transmission, realizing the intermittent passive vibration monitoring of the transformer for 16 times per day. Therefore, the proposed method has a promising engineering application prospect.