An Investigation of Voltage Unbalance in Low Voltage Distribution Networks with High Levels of SSEG

According to a recent study carried out for DTI and Ofgem, installed small-scale embedded generation (SSEG) capacity in the UK could grow to as much as 8GW by 2015. This anticipated growth offers significant environmental benefits but also technical issues regarding network integration and operation. Current EPSRC-funded research in The New and Renewable Energy Group at Durham university seeks to address these issues. Since small-scale embedded generators (SSEGs) are likely to use single-phase connections, voltage unbalance has the potential to become a serious concern for distribution network operators. Voltage unbalance in distribution networks is undesirable as it can cause problems for three phase load equipment and generators. This paper presents a dynamic model that is used to investigate the degree to which SSEG contributes to voltage unbalance in a generic LV network. The model is based on the IEC technical report 60725 and on data approved by work stream 3 of the DTI/Ofgem technical steering group (TSG)