Investigation of the reverse power flow requirements of high penetrations of small-scale embedded generation

The research carried out to investigate the ability of power transformers to facilitate the required power flows associated with the anticipated high penetrations of small scale embedded generation (SSEG), within small-scale energy zones (SSEZs) is described. A small-scale energy zone is defined as a section of low-voltage, network with a high penetration of SSEGs, controllable loads and energy storage units. SSEZs, coupled with active control techniques, have the potential to assist the growth of SSEGs by removing network constraints and enabling blocks of aggregated and controlled SSEGs to participate more effectively in energy markets and network operational tasks. The research focused on identifying the reverse power flow and thermal-rating constraints imposed by power transformers. The analysis was performed using an approved UK generic PSCAD/EMTDC electrical network model, with varying levels of SSEGs. Simulations were carried out examining cases with a uniform distribution of SSEGs contained within a number of SSEZs. It was observed that in some cases the reverse power flow capability of the primary transformers would exceed if each customer installed an SSEG with a rating of approximately 1 kW.