The monitoring of power quality using low-cost smart Web sensors

The problem of power quality (PQ) concerns the interference which can be present in the mains. These electromagnetic disturbances can cover a large interval of frequencies and can be present in industrial, domestic as well as commercial systems. As the main negative effects we can mention the high order harmonics, voltage fluctuations, flicker and disturbances with high slew-rates. The monitoring of the PQ of supply networks is then an issue of worldwide interest. It is frequently indispensable to measure PQ indexes in wide electric power plant or in industrial zones. To this aim a low-cost smart Web sensor has been designed and implemented to acquire, process and transmit data over a 802.3 network. It is organized in a multi microcontrollers system: the first one dedicated to the data acquisition and the other to data processing, dynamic HTML pages construction and TCP/IP stack management. Key features of the realised device are low-cost, data processing and remote communication capabilities, the possibility to provide date with any Internet browser. In the paper the main steps of design, implementation and characterization of the proposed system are given.