Artificial intelligence (AI) can potentially improve the reliability of transformer protection by fusing multiple features. However

owing to the data scarcity of inrush current and internal fault

the existing methods face the problem of poor generalizability. In this paper

a denoising-classification neural network (DCNN) is proposed

one which integrates a convolutional auto-encoder (CAE) and a convolutional neural network (CNN)

and is used to develop a reliable transformer protection scheme by identifying the exciting voltage-differential current curve (VICur). In the DCNN

CAE shares its encoder part with the CNN

where the CNN combines the encoder and a classifier. Based on the interaction of the CAE reconstruction process and the CNN classification process

the CAE regards the saturated features of the VICur as noise and removes them accurately. Consequently

it guides CNN to focus on the unsaturated features of the VICur. The unsaturated part of the VICur approximates an ellipse

and this significantly differentiates between a healthy and faulty transformer. Therefore

the unsaturated features extracted by the CNN help to decrease the data ergodicity requirement of AI and improve the generalizability. Finally

a CNN which is trained well by the DCNN is used to develop a protection scheme. PSCAD simulations and dynamic model experiments verify its superior performance.