Due to the continually increasing levels of penetration of distributed generation the correct operation of Loss-Of-Mains protection is of prime importance. Many UK utilities report persistent problems relating to incorrect operation of the ROCOF and Vector Shift methods which are currently the most commonly applied methods for Loss-Of-Mains (LOM) detection.
The main focus of this paper is to demonstrate the problems associated with these methods through detailed dynamic modelling of existing available relays. The ability to investigate the transient response of the LOM protection to various system events highlights the main weaknesses of the existing methods, and more importantly, provides the means of quantitative analysis and better understanding of these weaknesses. Consequently, the dynamic analysis of the protective algorithms supports the identification of best compromise settings and gives insight to the future areas requiring improvement.
R. Bugdal, A. Dysko, G. Burt, J. McDonald, Proc. 15th International Conference on Power System Protection; Bled, Slovenia, September 2006, pp. 139-144
KEYWORDS: Distributed generation, islanding, loss of mains, power system protection.