The application of fluorescent optical fiber in partial discharge detection of Ring Main Unit

Ring Main Units (RMU) are commonly used in the power system. At present, there is no example of partial discharge (PD) detection in RMU by optical method. In this article, the PD in RMU was detected by optical method. Meanwhile, the characteristics of the optical signals and the influential factors have been analyzed. The phase, amplitude and quantity characteristics of the PD optical signals in the positive and negative half cycle was analyzed and listed and we can find the PD optical signals under four typical insulating defects have their own characteristics; if the output of the PMT have not reach it saturation value, the maximum amplitude of the optical signals will increase with the increase of the applied voltage while the average amplitude of the optical signals did not always increase except the insulation gap defect; besides, the number of the optical signals also have a positive relationship with the applied voltage. When the optical receiving length quadruple, the initial PD voltage (IPDV) of optical method has decreased about 14.7% while the number of PD optical signals has increased about 1046.5%; when the pressure changing from 0.1 MPa to 0.14 MPa, the IPDV has increased about 83.65% while the signals number has decreased about 36.23%; when the distance between the optical fiber and the defect model changing from 2.5 cm to 7.5 cm, the IPDV has increased about 9.3% while the signals number has decreased about 65.7%.