Evaluation of power transformer state ranking based on grey system theory

Grey relational analysis (GRA) is part of grey system theory and suitable for solving the problems with complicated interrelationship between the multiple factors and variables. The State ranking scheme of power transformer based on dissolved gas-in-oil analysis characteristically recognized as grey system. In this paper, key gas method of DGA is used for state assessment of power transformer. The key gas data sets are evaluated strategically by applying the grey theory. The proposed model based on new sub-section linearity relations with target heart degree ranked the testing transformers into seven grades. A grey scale ranking score certainly helps in setting the priorities about investment and maintenance of transformer.