MITIGATION OF VOLTAGE UNBALACE IN RURAL LOW VOLTAGE NETWORKS USING SINGLE-PHASE BESS INVERTERS

Abstract

The increasing penetration of single-phase equipment in the distribution system, such as photovoltaic (PV) inverters and electric vehicle (EV) chargers, may cause an increase of voltage unbalance levels, thus leading to detrimental effects on the distribution system and the equipment connected to it. This research work aims to control single-phase battery energy storage (BESS) units to mitigate unbalance conditions. Single-phase load demands are modelled using real data and voltage unbalance is quantified by using the ‘voltage unbalance factor’ as defined in IEC 61000-2-2. The BESS units are modelled in detail including the main electrical components and the control system. The BESS inverters are controlled to supply active and reactive power demand of the load, thus limiting the unbalance levels in the network. The operating point of each BESS is also monitored to avoid overloading of the units. Voltage unbalance factor is monitored at various locations, without and with the BESSs, and the impact of the proposed control system is assessed considering realistic operating conditions based on measurements of load demand with a 1-minute resolution.