Monitoring voltage and frequency in smart distribution grids. A case study on data compression and accessibility.

Synchronized measurements became recently an affordable tool ready to be implemented not only at transmission system level but also at distribution level, mostly in conjunction with the applicability of the smart grid approach. As a preliminary step of introducing PMUs on a larger scale, extensive measurements campaigns, primarily dedicated to power quality purposes, were conducted within medium and low voltage grid in Romania. The extremely high volume of data was stored in a special dedicated database, from which information regarding events can be retrieved together with their associated local time stamp. In this paper, data resulting from several voltage waveform long-term monitoring campaigns are studied as to highlight their relevance both to the steady-state conditions and event identification of the distribution grids. Communication issues are also highlighted, as most of the monitoring units are located in remote areas, without a dedicated physical layer for data transfer.