Power quality enhancing in distribution utilities

One of the most concerning disturbances affecting power quality are voltage sags. Their major source are short-circuits on the utility lines. Faults many kilometres from the disturbed process will generate a momentary voltage sag in the electrical environment to the end user. A reduction of the short-circuit current magnitude may lead to a substantial power quality improvement because the majority of sensitive industrial processes (including computer system, power electronics and variable speed drives) are capable of riding through a sag of a very limited amplitude. Several solutions for Fault Current Limiters (FCLs) design have been described in the recent scientific literature. Nevertheless, the so far proposed FCLs are complex, expensive and may lead to additional operation problems decreasing the distribution reliability. The paper analyses and discusses a possibility of fault current reduction by means of simple permanent reactors and no control circuits, so as to intrinsically overcome most of the above cons.