Modelling and Stability Assessment of Future Grid Scenarios

Abstract

With the increased penetration of intermittent renewable energy sources (RESs) in future grids (FGs), balancing between supply and demand will become more dependent on demand response (DR) and energy storage. So far, FG feasibility studies, especially those claiming a long-term view, typically do not model the electrical network and/or the effect of DR. Thus, in this thesis, we first present a simulation platform for performance and stability assessment of FG scenarios. The platform considers market simulation, load flow calculation and stability assessment together. Using the platform, we illustrate how displacing conventional generators with RESs, especially inverter-based and intermittent RESs, could have significant impacts on performance and stability of FGs, confirming the importance of stability assessment for FG feasibility studies. Second, to carry out accurate stability analysis of FG scenarios, we need a representation of the aggregate demand including the effect of emerging demand-side technologies (distributed generation (DG), DR and storage). In this research, we propose generic demand models including the aggregated impact of price-responsive users equipped with emerging demand-side technologies (prosumers). The proposed models capture essential behaviour of the prosumers without giving lots of detail which is costly in repeated use for applications such as scenario comparisons. So, such models demand some simplifications, just as conventional generic load modelling did. The proposed frameworks are based on the unit commitment (UC) problem aiming to minimise the system cost. The conventional demand model in the associated optimisation formulations are augmented by including the aggregated influences of prosumers equipped with rooftop photovoltaics (PV)-battery systems. It is noted that as the frameworks are generic, they are capable of easy integration of other demand-side technologies as well. The developed frameworks are intended specifically for modelling net demand by including the impact of prosumers in FG scenario studies. Nevertheless, they do not assume any particular market structure. As such, they are not suitable for modelling of existing electricity markets, but rather their aim are to capture the behaviour of future electricity markets provided a suitable market structure is adopted. Finally, the impact of prosumers on performance and voltage stability of the Australian National Electricity Market (NEM) is studied with the increased penetration of RESs in the grid. We have considered different penetrations of RESs, and assessed the influence of different penetrations of prosumers on the balancing, loadability and voltage stability of the NEM.