Measurement of tanδ based on absolute and comparative method

Finding insulation faults in time and effectively is very meaningful to guarantee the safety of power delivery and increase the reliability of power supply. An effective way is to measure dielectric loss tangent (tanδ) of high-voltage capacitive-type equipment on-line, which is an important parameter to reflect insulation condition. In this paper, a new way by use of divided capacitance is presented. Through measuring the voltage angle of divided capacitance connected with equipment, the comparative value of tanδ between different equipment in same phase can be obtained. The absolute of tanδ can be obtained by the angle between the voltage of bus and the voltage of divided capacitance. The insulation quality of equipment can be determined by both values. Because the angle is obtained from divided capacitance voltage, the ability of anti-interference is obviously increased. In this paper, an approach of tanδ measurement based on ANN is presented. By analysis and simulation test, feasibility and effectiveness of this way are verified