In power utilities, grid operators monitor power-quality phenomena such as voltage sag at several substations to obtain an overview of the general network state and evolution of power quality. Collections of these huge online data from disturbance recorders involved long and tedious downloading process, usage of IEC 61850 or internet protocols consumed bandwidth and causes traffic congestion and collisions with IEDs within a subsation or other users between subsations and control centres. This paper describes an integrated application of power quality monitoring system for a modelled substation over the IEC 61850 standard developed in Java programming language. The application used wavelet compression technique for transmission of voltage sag waveform over IEC 61850 standard and then internet to a control centre. Analysis done shows that the correct selection of mother wavelet can achieve over 90% data compression ability while preserving all significant power quality features required for power quality waveform analysis.