“…In terms of SPD assessment, many algorithms have been proposed, for example, the discrete wavelet transform (DWT) [2], empirical mode decomposition [3,4], the S-transform (ST) [5][6][7][8], the Kalman filter (KF) [9], etc. However, the actual PQ events generally consist of two or more SPDs which occur simultaneously, i.e., MPDs [10,11]. These MPDs, including sag, swell, interruption, harmonic, flicker, oscillation, impulse, notch and other SPDs proposed in [12][13][14][15], carry a high risk of causing economic losses and serious damage to electrical elements.…”