Simulation Study on Propagation Characteristics of Optical Signals Excited by Partial Discharge in GIS

PD (partial discharge) is one of the most effective parameters to evaluate the insulation condition of power equipment. When PD happens, the optical signals will be emitted from the discharge sources. PD can be detected by measuring the optical signals. The PD optical method has electromagnetic immunity and especially suitable for the GIS (gas insulated switchgears) system which has a totally enclosure structure. At present, the related studies about development of optical sensors, optical detection of typical defects, and analysis of relationship between PD electrical and optical signals have been conducted in laboratory. However, the researches on propagation characteristics of PD optical signals are lack. In order to study the effects of propagation distance, GIS structure, receiving angle, and GIS component on the characteristics of optical signals induced by PD in GIS, a simulation model is built based on the size and structure of a physical GIS in this work. The photon amount and luminous flux detected by optical sensor under the condition of different distance, different GIS structure types, different positions of discharge source, and existing insulator with air hole are investigated. The results show that the photon amount and change rate of photon number will decrease with the increasing in distance between optical sensor and discharge source. the optical signals are the strongest when the PD source directly faces the detection sensor. The attenuation of optical signals is mainly caused by the hide of the GIS component when the detection angles change. With the increasing of voltage levels of GIS, the attenuation of optical signals is more obvious. The maximum change rate of photon number detected by the sensor in the L type GIS are about 61% of that in the line type GIS, which are 45% in the T type GIS. The related results can provide support for the installation of optical sensor and detection region of optical method.