Review of grid applications with the Zurich 1 MW battery energy storage system

a b s t r a c t Battery energy storage systems (BESSs), while at the moment still expensive, are from a technical point of view exceptionally well suited to support a distribution system operator (DSO) in the challenges created by increasing distributed, fluctuating and uncertain generation from renewable energy sources (RES), as well as by the unbundling of electricity retailing and grid operation. This paper presents three grid applications and measurement results from the grid-connected Zurich 1 MW BESS. Specifically, provision of frequency reserves, peak shaving and islanded operation of a microgrid are discussed in detail. The battery unit is able to perform these diverse tasks with outstanding quality. For the provision of frequency reserves the system has passed all prequalification requirements posed by the transmission system operator (TSO) in order to be granted access to the ancilliary services market. Along with these appli- cations, the paper aims to communicate the experience gained in designing proper control frameworks, communication infrastructure and the knowledge acquired concerning BESSs behavior.