The major problem in current online diagnosis and analysis for power system oscillation is mainly concerned with finding the oscillation source in a fast and correct way using the data collected by the Wide Area Measurement System (WAMS). This paper for the first time proposes a scheme of cut set energy based on WAMS. Independent of accurate parameters

the scheme can make full use of WAMS data based on cut set energy construction and fast calculation to locate the source during oscillation. Afterwards

a scheme of torque decomposition is proposed

based on which the controller's torque can be divided into damping torque and synchronous torque by calculation through WAMS data

and this paper puts forward the abnormal response and simulation models calibration of influential controllers. Analysis of an oscillation case shows how the cut set energy scheme and the torque decomposition scheme are applied in a real-world power system

and the schemes are proven to be reliable and practical in identifying and locating oscillation sources.