The subject addressed in this paper is the intra-hour scheduling of a distributed battery energy storage system (BESS). The case study is about a lithium-ion BESS integrated in a low voltage (LV) distribution system with residential customers and photovoltaic (PV) generation in the Netherlands. The BESS has been developed to enable field-testing and research of energy storage technologies in LV distribution grids, with emphasis on network support functions. As part of the research related to electricity markets, a proposal is presented about the economic optimisation of the BESS, whereas the simulation scenario addresses the passive contribution within the Dutch imbalance settlement system. Energy storage solutions can provide an attractive option for the integration of renewable energy sources and the establishment of efficient generation and delivery of electrical power. In the Netherlands, market parties have an incentive to assist the Transmission System Operator (TSO) in correcting system imbalances, largely attributable to the organisation of the system. The Dutch TSO publishes the system balance position and imbalance price close to real-time. This information can be used by market participants to voluntary contribute to the system balance by utilising non-contracted control power. This approach is called passive contribution and is believed to result in a substantial reduction in the required control energy. The imbalance settlement in the Netherlands for passive balancing is based on the net volumes of provided control energy per settlement period. Therefore, market participants might try to minimise or maximise the net amount of energy per settlement period when the system state is explicitly short or long. Assuming certain predictions of the system state and imbalance prices, the formulation of the optimisation problem is the maximisation of a profit function, and is solved by utilising an internal model of the BESS to plan the future response of the charging and discharging process over a receding ...