In this paper, a data stream architecture is presented for electrical power quality (PQ) which is called PQStream. PQStream is developed to process and manage time-evolving data coming from the country-wide mobile measurements of electrical PQ parameters of the Turkish Electricity Transmission System. It is a full-fledged system with a data measurement module which carries out processing of continuous PQ data, a stream database which stores the output of the measurement module, and finally a Graphical User Interface for retrospective analysis of the PQ data stored in the stream database. The presented model is deployed and is available to PQ experts, academicians and researchers of the area. As further studies, data mining methods such as classification and clustering algorithms will be applied in order to deduce useful PQ information from this database of PQ data.