Cross-equipment Evaluation of Partial Discharge Measurement and Diagnosis Techniques in Electric Power Apparatus for Transmission and Distribution

Partial discharge (PD) measurement allows detection of insulation defects in various electric power apparatus before an insulation failure occurs. It can also improve the reliability of the insulation performance of apparatus, and support rational and economical design, lifetime prediction, and nondestructive inspection. Historically speaking, PD detection methods have evolved in each category of apparatus and power cables. However, there does not seem to exist what we call universality in PD detection technology that is available to all kinds of power equipment. This article specifically describes features, similarities, and differences of partial discharge measurement and diagnosis technologies for electric power apparatus used in transmission and distribution. The main task of this article lies in not simply reviewing PD measurement and diagnosis techniques but trying a cross-equipment evaluation. First, this article deals with similarities and differences among partial discharge detection techniques for typical power apparatuses including gas insulated switchgear, oil-immersed transformers, and power cables. In particular electrical measurement technology and electromagnetic measurement technology are compared selectively. The second subject is to describe signal-processing technologies, and discuss similarities and differences among equipment in terms of noise removal, location identification, and foreign particle identification. Finally, judgment methods and judgment criteria for equipment diagnoses as a whole are analyzed and described. These discussions are expected to clarify the positioning of the partial discharge measurement technologies for various equipment among all electric power apparatus, and support technological development in the future.