As power systems transition toward high shares of renewable energy, synchronous generators are being phased out. In their absence services including inertia, system strength and instantaneous fault currents must be provided by inverter-based resources. Inter-area and local oscillations may change in their nature at lower shares of conventional generation – thus inverter-based resources need to provide adequate damping power as well.

This contribution outlines how the key stability services can be provided from Battery Energy Storage Systems (BESS) and photovoltaic (PV) systems. BESS can be optimized to provide high amounts of inertia – to buffer the power imbalances of extreme events like system splits. Fast transient voltage control for both PV and BESS increases system strength and ensures a stiff local voltage. And PV and BESS further contribute to power oscillation damping, thereby mitigating both inter-area and local-area oscillations – even when the oscillatory modes related to synchronous machines change over time.

We will present how BESS can be the main anchors for stable system, and how PV systems contribute to stability. The focus is on the available technology, which is already in use.

One key scenario is the large active power disturbance as a result from e.g. a system split. This directly benefits from the extremely fast frequency support from inverter-based resources. But only the instantaneous reaction from inertia in BESS ensures the proper functioning of these frequency support functions (i.e. limited frequency sensitive mode), and even then load-frequency disconnection schemes may be necessary to stabilize the (partial) system. The combination of highly available and robust inertia along with load shedding plans and fast LFSM ensures safe and reliable power systems.

This paper presents the view from OEM perspective on how BESS, PV, and wind generation can collectively provide all the necessary ingredients for a stable and secure power system that is mainly based on renewable generation.