Mapping the frequency response adequacy of the Australian national electricity market

There is increasing concern about the security implications of running a low-inertia power system resulting from the extensive penetration of variable renewable energy sources that are connected through power electronic interface. In this context, this paper focuses on the analysis of frequency response adequacy of the power system operated by National Electricity Market (NEM) in Australia. Frequency response adequacy refers to the capability of a given portfolio of resources to maintain the frequency excursion characteristics within certain limits following a contingency event. Analysis for both generation and transmission contingencies events is conducted, with reference to the whole NEM and to South Australia as specific case studies. The analysis aims to provide clear insights into the relation between system inertia, frequency control ancillary services (FCAS), and the maximum allowed limits of the frequency excursion after contingency. To this end, specific frequency response security maps are introduced as a tool to represent the frequency excursion limits on a primary frequency response vs inertia chart. Several system conditions are studied, with results illustrating fundamental system limits with regards to secure operation, as well as exemplifying potential ways to reduce the frequency stability risk of the future NEM.