Detection of Dips, Swells and Interruptions in DC Power Network

The recent developments in power electronics have greatly increased the number of appliances that operate in DC and, contextually, the main distributed energy sources such as photovoltaic systems and fuel cells are inherently of DC nature. Therefore, a better integration of these devices into the electrical grid can be achieved with a direct connection in DC, avoiding all the additional losses due to the energy conversion stages currently employed in the traditional AC distribution grid. On the other hand, high voltage transmission in DC (HVDC) offers lower costs due to reduced losses in transmission. Nevertheless, at present, there is a lack of international standards that define Power Quality (PQ) metrics for DC grids. This paper makes a review of the technical report IEC-TR-63282 that is a first normative effort to this aim. Moreover, the authors suggest measuring methods to evaluate dips, swells and interruptions. The measuring method has been finally applied to PQ phenomena detected on simulated and experimental data to evaluate the effect of the time interval adopted in the assessment of these events.