Electricity transmission capacity expansion planning for Lesotho
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Date
2024
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Publisher
National University of Lesotho
Abstract
Transmission Expansion Planning (TEP) is crucial in identifying the optimal timing, location, and scale of new transmission lines and substations to ensure a reliable energy supply to consumers. In Lesotho, the expansion of transmission and distribution networks faces considerable challenges due to the country’s rugged, mountainous terrain, particularly in extending access to rural areas. However, the abundant potential for renewable energy generation from solar, wind, hydro and pumped storage provides a promising development pathway. Despite this potential, there is a significant lack of strategic planning in how Lesotho can expand its network to accommodate renewable energy projects while maintaining stability and reliability. This study utilized DIgSILENT PowerFactory to simulate network scenarios for 2023, 2030, and 2035, providing critical insights into potential congestion points when integrating new renewable generators into the grid. This study also provides critical insights into network stability and the necessity for strategic transmission line and substation expansion planning. The study aims to provide insight to Lesotho Electricity Company (LEC) as the transmission line operator to see where the network may encounter congestion when different generators are integrated into the network. Key renewable energy projects analysed include the 72 MW ’Muela Hydropower, 30 MW Ramarothole solar photovoltaic (PV), the 20 MW OnePower solar PV, the upgrade to 80 MW for Ramarothole, and the 66 MW Hirundo wind farms. The results show a 30% increase in transformer loadings from 2023 to 2030, with an additional 14% increase from 2030 to 2035, which highlights the growing demand for the existing infrastructure. Cost analysis for reinforcing the transmission infrastructure estimate the upgrade of transmission lines at USD 44,803,233.79 and transformer upgrades at USD 125,338,880.49. To meet the rising power demand and integrate renewable energy sources without compromising network stability, it is recommended that the Lesotho Electricity Company (LEC) invest in new power transformers at various substations to reinforce the existing transmission lines. This study provides the LEC with crucial guidance for strategic
TEP, ensuring the nation’s power grid can meet future energy needs while remaining stable and reliable.