Grand challenges in electric power engineering: extreme system reliability

Classical studies have focused on the calculation of power system reliability, for example as the loss of load probability, or the expected time of load unserved; and classical studies also describe how to use parallel circuits, increased generation margin, and component redundancy to improve reliability. However, contemporary thoughts on this topic are quite differently focused: modem power system reliability relates more to the following items than the classical subjects listed above: electric power quality; extreme bus voltage reliability, for example ´five nines´ (i.e., 0.99999 availability), or six nines or even higher; utilization of new transmission and distribution technologies for improvement of reliability; utilization of distributed energy sources (DERs) to improve reliability; working with manufacturers of information technology equipment to reduce load vulnerability; distributed rather than concentrated loads; and loop circuits for distribution systems. The author discusses these issues.