Optimal solution of weak spots problem in a grid system by means of facts devices

Abstract

Electrical power system functioning is permanently exposed to different disturbances which cause the regime parameters change. Every grid system contains elements whose regime parameters variations influence system’s sensitivity most of all. These elements are called weak spots and may represent nodes or branches of the electrical network. An original method of weak spots detection and efficient ways of decreasing grid system’s sensitivity are presented in this paper. The technique used to estimate the number of weak spots in a grid system is based on singular value decomposition of Jacobi inverse matrix called sensitivity matrix. The theory taken for analysis implies the investigation of right and left singular vectors components related to the minimal singular value of sensitivity matrix in order to detect the weak nodes of the power network. The optimal way to strengthen the weak spots adds up to the use of FACTS devices that represent a powerful technology capable to solve this problem. In this paper steady-state power flow models of Static VAR Compensator (SVC) and Static Synchronous Compensator (STATCOM) were used to solve the problem set above owing to their characteristics. Consequently their inclusion in Newton-Raphson method has shown the opportunity to control the nodal voltage magnitudes. Case studies are carried out for a test power grid and the results show that either of the FACTS devices is eminently suitable to strengthen the weak nodes that were found.