Power system planning using optimally designed transmission lines

Over the past several decades, transmission lines, the primary infrastructure for transporting electric energy across power systems, have largely maintained their traditional designs, despite significant shifts in supply and demand dynamics. The inherent operational limitations of these conventional designs continue to be a major constraint on grid loadability and are expected to remain so in the foreseeable future. To address this challenge, we propose the use of unconventional transmission lines optimally designed with enhanced power transfer capabilities, known as high-surge-impedance loading (HSIL) lines. The proposed HSIL configuration achieves a surge impedance loading of 1354.72 MW, representing a 41.04 % increase over that of conventional 500 kV lines with equivalent conductor weight and cross-sectional area. The impact of these lines on the planning of large-scale power systems is assessed through detailed transmission expansion planning (TEP) studies. Using a 17-bus 500 kV test system in three different loading scenarios, each analyzed under normal and N-1 contingency conditions, we compare the performance of conventional versus HSIL lines to connect a new load to a new location. Comprehensive economic analysis reveals that the implementation of HSIL lines results in substantial cost savings, thus presenting a technically robust and economically attractive solution for future power system planning. • Unconventional line design boosts SIL by 41% and reduces line width by 2.14×. • Maintains same conductor cross-section and weight as conventional 500 kV lines. • TEP study: Unconventional HSIL line needs fewer lines and bays than conventional, reducing costs. • Smaller Right-of-Way lowers environmental impact and land acquisition costs. • Comprehensive TEP study confirms major savings with unconventional vs. conventional lines.