Power transmission losses represent a significant challenge for electrical grids worldwide, impacting efficiency, reliability, and environmental sustainability. Utilities and grid operators can minimize energy wastage, improve grid performance, and ensure a more sustainable and reliable electricity supply for consumers by comprehending the factors behind transmission losses and implementing effective mitigation strategies. This study focuses on enhancing the understanding of the causes of Southern Regional Inter-State Transmission System (ISTS) losses through comprehensive operational analysis. By leveraging the real-time historical power flow data for the year 2023, it is aimed to identify the key factors contributing to ISTS losses in the Southern Region. Power flow data of ISTS lines at various voltage levels have been analyzed in order to derive the inter-dependence of various technical factors such as intra-day demand variations, insufficient generation resources during peak time, variability of renewable energy generation, and impact of interconnected regional grids and the environmental factors such as ambient temperature, ambient weather conditions on ISTS losses in the power system network. This study highlights the impact of different transmission systems on regional ISTS losses, identifying key areas within the transmission network that require focus to minimize the ISTS losses. It is recommended to implement adaptive control of HVDC set points, utilizing AI applications based on power flows in HVAC networks, as a strategy to minimize losses in the Southern Region ISTS, as indicated by the study’s findings.