Contents I. Introduction
Structural health monitoring has become a critical issue in many engineering applications [1]–[3], such as monitoring of dams, bridges, and buildings. For power transmission tower monitoring, early warnings of abnormal vibration allow operators to take preventative action [1], [2]. Tower vibration is mainly caused by wind action [3], [4]. Along coastal areas, such wind can increase to hurricane strength and induce devastating mechanical damage to transmission towers [5], [6]. Many methods have been reported for vibration measurement, such as capacitive [7], piezoelectric [8], [9], electrostatic [6], [10], and piezoresistive [11], [12] accelerometers. However, such methods are based on electromechanical principle and have a catastrophic disadvantage of requirement of electrical insulation, making them impossible used in high electric fields, such as power transmission tower. Therefore, such electrically based sensors are unsuitable for use in the presence of strong electric and magnetic fields. Measurement of the state of the transmission towers and transmission lines in real-time, especially during severe and unstable weather events, and over the structures’ lifetimes remains a key challenge for utility operators. Due to many intrinsic merits [13], [14], including small size, low cost, remote operation, high sensitivity, especially the immunity to electromagnetic interference, fiber-optic sensors, such as fiber Bragg grating [13], [15], [16], have been proposed for vibration (also called acceleration) measurement in high-voltage electrical systems. At present, fiber-optic sensors have been developed for many engineering applications, such as civil engineering [17], [18], the petroleum industry [19], [20], and transportation security [21], [22].
