• photovoltaic system;
  • uncertainties;
  • power supply reliability;
  • robust power system security.


A large amount of PV penetration may introduce uncertainties in future power system planning and operations. This paper proposes the concept of “Robust Security (RS)” and the “RS region” in order to investigate power system security in the presence of a large amount of uncertainties. The RS region is defined as the region of power system operation where the system is secure under uncertainties. It is shown that the region tends to shrink and disappear for a high degree of PV penetration. Emerging problems concerned with security in future power systems are investigated. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(1): 30–38, 2013; Published online in Wiley Online Library ( DOI 10.1002/eej.22289