Study on the Methodology Monitoring Transformer Bushing Insulation Defects

Abstract

Power transformer is the key equipment in power system. In view of the issues of the current bushing monitoring method, a new detection method of bushing insulation defects is proposed in this paper. According to the internal structure of bushing, the internal insulation defects are divided into three categories, including partial moisture, pollution, local insulation defects, the outer insulation of the bushing is equivalent to a resistance chain model. The entire bushing insulation is considered as a parallel between inner insulation and external insulation (inner Insulation is the main). This detection makes uses of the transient voltage measured from the transformer bushing and the transient current measured from the end shield down-lead as the signal source. The reference data dynamically generated is used to diagnosis and distinguish Insulation defects of Transformer bushing, according to the monitoring data of the bushing and the maximum of the reference data, the type of the bushing insulation defect and the severity can be sentenced. A large number of simulation results initially confirmed the effectiveness and feasibility of the proposed method.