Abstract
The deployability of new technologies is more realistic at a smaller scale, making the modeling of microgrids an important priority. Moreover, the accurate modeling of a microgrid is paramount when there is less room for error in a small system, where there is less ability of buses to share power. One convenient assumption made in transient stability analysis involves the assumption of an infinite bus with constant voltage and infinite inertia. This assumption does not hold for microgrids. In order to analyze a single machine as quickly and easily as using the Equal Area Criterion (EAC) method on a Single Machine Infinite-Bus (SMIB) example for a microgrid, I will develop a single-machine semi-infinite bus model, which should yield improved results while avoiding the work of analyzing every bus in the network.
The Single-Machine Semi-Infinite Bus algorithm did not increase accuracy or reduce calculation efforts. It did, however, attempt to solve the problem with a novel approach. Additionally, it demonstrated that the PEBS and EAC (equal area criterion) method produce similar results, but PEBS results are more accurate. Perhaps most significantly, it highlighted the biggest flaw in the EAC method, which provides insight to developing a more accurate model. The Single-Machine Semi-Infinite Bus focused on the constant frequency and infinite inertia assumptions of the EAC method. Surprisingly, addressing these assumptions did not affect the result as profoundly as expected. Instead, it became apparent that both approaches (that is, the original EAC and my proposed PEBS method) focus only on the analyzed bus, and do not account for the effects felt on the rest of the microgrid. The simulation shows that there are significant impacts on other buses in the system. The algorithm was written assuming that a microgrid would offer less support to the machine, and therefore analyzing a single machine was still a valuable analysis. However, after the analysis was complete, it became apparent that single-machine analysis is not very valuable in a microgrid context. The effects of less inertia and more volatile frequency is felt more at other parts of the grid than at the faulted bus, as shown by the similarity of the original EAC SMIB result to the novel Single-Machine Semi-Infinite Bus PEBS result.