Multiple Swing Out-of-Step Relaying

Abstract

The reduced stability margin, at which power systems are being operated these days, has encouraged the power industry to come up with new ideas to guarantee a continuous and reliable operation of the bulk interconnected system. The development of the synchronized Phasor Measurement technology, and its deployment in several locations in the network, has introduced a promising means to protect power systems from undesired conditions. This research effort describes a methodology to handle transient stability in power systems using Wide Area Measurements. A correct identification of transiently stable and unstable power oscillations can be achieved with the use of the Out-of-Step protection technique presented in this document. The development of this idea is explained through the analysis of small power system models, and tested in three different operating conditions of the state of California. The main contribution of this research work, to the Out-of-Step relaying theory, is the identification of multiple unstable swings after a given disturbance. In other words, an Out-of-Step protection scheme that handles a network that behaves as a multi-machine system is presented.