Harmonics are periodic distortions of voltage, recent, or electric power sine waves. Harmonics in electric power distribution systems are sometimes attributable to non-linear masses which include switched mode dc electric power materials and adjustable pace motor drives. Gi?i m?i (bao g?m t?t c? gi?i nào có s? thay ??i, c?p nh?t m?i ho?c ?i?u ch