Comparative study on two modulation principles of fiber optic current sensors

Fiber optic current sensors (FOCS), an important current sensor, has been widely used in HVDC transmission system. Its operation reliability and measurement accuracy are directly related to the safe and stable operation of power grid. At present, there are two main FOCT modulation modes in power system, of which are PZT birefringence modulator and LiNbO3 birefringence modulator. They are made respectively by Shanghai Runjing Energy Technology Co and Xuji Group Corporation. We select products of different technology routes from the above two suppliers, and carry out comparative research from different aspects such as modulation principle, overall design, device selection, manufacturing process, operation characteristics of the whole machine and so on. Furthermore, we theoretically and statistically compare the differences in product design and operation characteristics, so as to facilitate power system users to select products according to the corresponding use scenarios.