Peak Demand Management on Distribution Networks using Coordinated Behind-The-Meter PV / Battery Systems: The Bruny Island Battery Trial

Abstract

We introduce the Bruny Island Battery Trial, a collaborative research project which will see around 40 photovoltaic and battery systems installed on Bruny Island in Tasmania by April 2017. This fleet of battery systems will operate via a coordinated optimisation approach featuring network constraint based price signals, to alleviate network capacity problems associated with peak-demand events, which are currently solved by on-island diesel generation. Battery owners meanwhile will benefit from two income streams, derived from time-shifting for local tariff optimisation and from network support. We show, via analysis of power flow data measurements over the preceding two-year period, that peak demand on the island is characterised by early morning and early evening peaks, and as such we demonstrate that PV systems alone will only ever have inconsequential impact upon peak demand mitigation. In contrast, we demonstrate that 40 residential-sized PV / battery systems spread across the island would have reduced peak demand over the two-year period by up to 150 kW, would have reduced the number of diesel starts from 43 down to 14 and reduced generator running hours and annual diesel energy production by up to 83% and 91% respectively. Furthermore we show, by modelling the network, the extent to which voltage is able to be controlled, particularly at the extents of the network, by such a deployment of batteries. We conclude that a fleet of behind-the-meter PV / battery systems, if coordinated with network requirements in mind, is an effective alternative to traditional network solutions in addressing peak demand and in addressing voltage issues.