Separation event-constrained optimal power flow to enhance resilience in low-inertia power systems

Abstract

Weakly interconnected power systems face separation risk during extreme weather events or due to cascading failures. These contingencies may become particularly severe in low-inertia grids, where the sub-regions resulting after system split need to procure enough resources to respond to low (importing areas) and high (exporting areas) frequency conditions. This paper introduces a separation event-constrained optimal power flow (SECOPF) with considerations of inertia and frequency response resources allocation in each balancing area to be capable to withstand, besides the largest generation and load contingencies, also the loss of selected interconnectors. The model, cast as mixed integer linear program, is tested on a reduced version of the Australian power system and validated via dynamic simulation. The results show how the system's frequency resilience to extreme events can be effectively enhanced for both high- and low-frequency conditions that arise in different areas after an interconnector's trip . This is achieved by co-optimising the interconnector flow magnitudes along with the distribution of frequency response resources and inertia levels in each area.