Distribution system security region (DSSR) for smart grid

The region-based method has been successfully applied in transmission systems. This paper proposes the definition, model, and applications of security region for distribution systems. With the ongoing smart grid initiatives, distribution operation will be changed with a large amount of network information available in real time. This is the motivation of an accurate calculation of the security boundary. First, this paper models distribution system security boundary in the Euclidean space as several intersected hyperplanes. It is found that each boundary is a piecewise linear function, consisting of several pieces of hyperplanes. Second, distribution system security region (DSSR) is then modeled as the space surrounded by the security boundaries and the set of all operating points that ensure the distribution system N-1 security. Third, distance from an operating point to a security boundary is formulated and a new index is also presented for security evaluation. The proposed DSSR-based security assessment method provides a new approach for future smart distribution system operation. Finally, the results from a real distribution system have demonstrated the effectiveness of the proposed concepts and methods.