Essential System Services in Grids Dominated by Renewable Energy

As the proportion of variable inverter-based renewable energy generation in electricity systems increases from a minority to the majority of total supply, the complexity and cost of providing ancillary system services increases in parallel. Australia is experiencing this shift now - from having the third most carbon-intensive electricity sector in the world in 2010, to now having penetrations of variable renewable energy (VRE) regularly reaching 100 percent in some regions, with world-leading uptake of distributed energy resources (DER). This paper presents pioneering work exploring new technical, economic and regulatory frameworks for the provision of Essential System Services (ESS), also known as ancillary services, in power systems dominated by variable inverter-based renewable energy resources. We explore the recent application of the concept of demand curves and nomograms to the procurement of ESS, and emerging design principles for frameworks in facilitating the evolution from default provision of system services by synchronous generation, to co-optimisation of services through unit commitment, to independent provision of services through inverter based resources. The paper also analyses the recent technical and financial success of the world's largest battery, the Hornsdale Power Reserve in South Australia, and its ability to inform how future electricity market frameworks may incentivize and accommodate new technological capability, both first and Nth of a kind systems. Finally, the paper reviews emerging energy system technological capability, including the provision of synthetic inertia and RoCoF control, grid-forming inverters, and advanced DER aggregation in providing ESS and system restart capability for secure, resilient and island-able grids.