This study proposes a new algorithm, which makes use of S-transform modulus time-frequency matrix to detect the power quality transient disturbance. And respective mathematical models are established according to transient disturbances such as voltage sags, voltage rises, voltage interruption and transient oscillation. It calculates the modulus time-frequency matrix of the four disturbance signals by using S-transform and extracts their features. Simulation and analysis are made in Matlab. The simulation results show that the proposed algorithm can extract the features of different disturbance...