Fault diagnosis method and device for high-voltage totally-enclosed composite apparatus

The invention provides a fault diagnosis method and device for a high-voltage totally-enclosed combined electric appliance, and the method comprises the steps: obtaining first state data under a specified dimension in an electric appliance cavity in a historical time period, and obtaining a fault diagnosis result based on the data of which the fluctuation amplitude is smaller than a preset threshold value in a continuous preset time period in the first state data; and determining a first feature vector of the electric appliance under the specified dimension, so as to determine a slow change rate of the electric appliance under the specified dimension based on second state data under the specified dimension in the electric appliance chamber within the current preset time length and the first feature vector, and then, determining whether the electric appliance has a fault associated with the specified dimension based on the slow change rate. Therefore, based on the slow change rate, whether the electric applian