Partial discharges (PDs) are an electrical phenomenon that occurs within a transformer whenever the voltage stress is
sufficient to produce ionization in voids or inclusions within a solid dielectric, at conductor/dielectric interfaces, or in
bubbles within liquid dielectrics such as oil; high-frequency transient current discharges will then appear repeatedly and
will progressively deteriorate the insulation, ultimately leading to breakdown. Fiber sensor has great potential on the
partial discharge detection in high-voltage equipment for its immunity to electromagnetic interference and it can take
direct measurement in the high voltage equipment. The energy released in PDs produces a number of effects, resulting in
flash, chemical and structural changes and electromagnetic emissions and so on. Acoustic PD detection is based on the
mechanical pressure wave emitted from the discharge and fluorescent fiber PD detection is based on the emitted light
produced by ionization, excitation and recombination processes during the discharge. Both of the two methods have the
shortage of weak anti-interference capacity in the physical environment, like thunder or other sound source. In order to
avoid the false report, an all-fiber combined PD detection system of the two methods is developed in this paper. In the
system the fluorescent fiber PD sensor is considered as a reference signal, three F-P based PD detection sensors are used
to both monitor the PD intensity and calculate the exact position of the discharge source. Considering the wave band of
the F-P cavity and the fluorescent probe are quite different, the reflection spectrum of the F-P cavity is in the infrared
region, however the fluorescent probe is about 600nm to 700nm, thus the F-P sensor and fluorescent fiber probe can be
connected in one fiber and the reflection light can be detected by two different detectors without mutual interference.
The all-fiber partial discharge monitoring system not only can detect the PDs but also can ensure the position of the PD
source and is of great anti-interference capacity in harsh environment.
Smart Grid is a promising power delivery infrastructure integrated with communication and information technologies.
By incorporating monitoring, analysis, control and communications facilities, it is possible to optimize the performance
of the power system, allowing electricity to be delivered more efficiently. In the transmission and distribution sector, online
monitoring of transmission lines and primary equipments is of vital importance, which can improve the reliability of
power systems effectively. Optical fiber sensors can provide an alternative to conventional electrical sensors for such
applications, with high accuracy, long term stability, streamlined installation, and premium performance under harsh
environmental conditions. These optical fiber sensors offer immunity to EMI and extraordinary resistance to mechanical
fatigue and therefore they will have great potential in on-line monitoring applications in Smart Grid. In this paper, we
present a summary of the on-line monitoring needs of Smart Grid and explore the use of optical fiber sensors in Smart
Grid. First, the on-line monitoring needs of Smart Grid is summarized. Second, a review on optical fiber sensor
technology is given. Third, the application of optical fiber sensors in Smart Grid is discussed, including transmission line
monitoring, primary equipment monitoring and substation perimeter intrusion detection. Finally, future research
directions of optical fiber sensors for power systems are discussed. Compared to other traditional electrical sensors, the
application of optical fiber sensors in Smart Grid has unique advantages.