A new method for detection and classification of power quality (PQ) disturbances in single-phase power systems is presented in this paper. The method detects transients, waveform distortions and short and long duration disturbances such as sags or swells. The method was developed with special consideration for its suitability for implementation in a digital signal processor (DSP) and for real-time operation. The proposed method was implemented and its performance was verified on detection of real PQ disturbances in a PC based system monitoring a single-phase power system.