Improved Monitoring and Diagnosis of Transformer Solid Insulation Using Pertinent Chemical Indicators

Abstract

Transformers are generally considered to be the costliest assets in a power network. The lifetime of a transformer is mainly attributable to the condition of its solid insulation, which in turn is measured and described according to the degree of polymerization (DP) of the cellulose. Since the determination of the DP index is complex and time-consuming and requires the transformer to be taken out of service, utilities prefer indirect and non-invasive methods of determining the DP based on the byproduct of cellulose aging. This paper analyzes solid insulation degradation by measuring the furan concentration, recently introduced methanol, and dissolved gases like carbon oxides and hydrogen, in the insulating oil. A group of service-aged distribution transformers were selected for practical investigation based on oil samples and different kinds of tests. Based on the maintenance and planning strategy of the power utility and a weighted combination of measured chemical indicators, a neural network was also developed to categorize the state of the transformer in certain classes. The method proved to be able to improve the diagnostic capability of chemical indicators, thus providing power utilities with more reliable maintenance tools and avoiding catastrophic failure of transformers.

The Method for Improving the Effect of Oil-Replacement on Aging Assessment of Power Transformers Insulation Based on Methanol

“…The equation ( 6) is established at 130 • C while the verification experiment temperature T 2 is 120 • C, so the verification experiment results (T 2 =120 • C) need to be transformed to T 1 =130 • C by equation (7). Furtherly, the equation ( 7) could be substituted into equation (8).…”

“…The insulation oil could recover its insulation property by replacing the oil, while the insulation paper is inconvenience to be replaced for power transformers [6], [7], [8]. Therefore, the operation conditions of transformers are determined by the aging state of insulation papers, and adopting the effective The associate editor coordinating the review of this manuscript and approving it for publication was Guillaume Parent .…”

A review on a novel method for aging evaluation of transformer insulating paper based on methanol

“…In the internal insulation system of oil immersed transformer, the internal insulation life of transformer depends on the life of insulating paper, because insulating oil is replaceable, but cellulose paper as solid insulation is inconvenient to be repaired or replaced [13]. Therefore, the key way to estimate the insulation life of transformer is the aging state of cellulose paper [14,15].…”