Potential Benefits and Challenges of Employing Inertia Distribution Indexing in RMS Simulations

Globally there has been a trend towards increasing penetration of Converter Fed Generation (CFG) into main power systems, and a reduction of conventional synchronous generation. One of the recent research areas, that has attracted some significant consideration is the uneven distribution of inertia through a power system and the potential local variations of frequency and Rate of Change of Frequency (RoCoF). This paper uses the IEEE 9-Bus test network to develop show how measurement of frequency within RMS simulation packages is of critical importance and that the current use of an Inertia Distribution Index (IDI) can overlook critical generators when a very uneven distribution of inertia exists. An alternative, based on frequency difference magnitude, is developed in this paper as a more robust approach.