Optimising Rural SWER Distribution Systems in Queensland

This research project aimed to determine if the impacts of decentralised battery storage systems on the Cotton Gin SWER system would improve the performance of the SWER network compared to the current centralised GUSS. The Cotton Gin SWER system is located near St George, Queensland. To begin the research project, it was necessary to conduct a literature review on Single Wire Earth Return (SWER) systems and decentralised battery storage systems. To conduct the analysis, research on system modelling was required for both the SWER system and battery storage systems. For the analysis, customer load profile data was provided by Ergon Energy to determine the average loads across the Cotton Gin SWER system. The first stage of modelling required the development of a scaled line diagram of the Cotton Gin SWER system. The second stage in modelling was to develop a load flow program in MATLAB for the Cotton Gin SWER system. The third stage was to simulate through the HOMER Pro program developed by Homer Energy, the different decentralised battery storage systems available on the market. The three different types of decentralised battery storage types analysed were TESLA Powerwall 2 - Lithium Ion battery, Nickle Iron battery and BAE Lead Acid battery. A detailed business case was conducted outlining the cost benefit analysis of the optimal decentralised battery storage system. From the results, it was determined that the TESLA Powerwall 2 battery performed the best overall for cost and efficiency. Although the current centralised Grid Utility Support System (GUSS) is effective, this research project discovered that there are opportunities for improvements in GUSS by decentralising the battery storage support system. The benefits of decentralising the GUSS is the reduction of system loses across the entire network, improved voltage regulation and the ability to improve the overall capacity of the SWER network. This research recommends charging the decentralised battery storage at the minimum demand to reduce system loses and improve the delivery capacity across the SWER network. From the load flow data provide by Ergon it was evident that the peak load could be shifted by the use of battery storage systems which would reduce the amount of losses and improve the system performance. From the load flow analysis, it was observed that when the decentralised batteries are included in the SWER system, the system losses were significantly lower. After evaluating the data from the load flow and HOMER Pro analysis it is evident that decentralised battery storage will have a future in electricity supply within rural and remote areas