Comparison of AC and DC Transmission Technologies and the Energy-saving Advantages of HVDC in Long-distance Transmission

Abstract

While fossil fuel power generation is promoting economic and social development, it has also triggered serious environmental problems. To achieve the strategic goals of carbon peaking and carbon neutrality, the large-scale development of renewable energy sources such as wind power, hydropower, and solar energy has become an important path. However, renewable energy power generation bases are usually far from load centers. Researching efficient long-distance transmission technologies is of crucial significance for the consumption of clean energy and the low-carbon development of power grids. This article systematically compares the technical characteristics and application scenarios of alternating current (AC) transmission and direct current (DC) transmission. Taking a 2000 km transmission distance as a typical scenario, based on the transmission line loss model, the energy consumption characteristics of the converter station, and the comprehensive efficiency index of the system, the energy-saving advantages of high-voltage direct current (HVDC) transmission in long-distance transmission were quantitatively analyzed. Research shows that in a 2000km transmission scenario, the line resistance loss of the HVDC system is reduced by approximately 40% compared to the AC system of the same capacity. The additional loss at the converter station can be controlled within 5% through new topology optimization, and the overall transmission efficiency is improved by 8 to 12 percentage points. Moreover, HVDC has significant advantages in reducing corridor land occupation and lowering the impact on the electromagnetic environment, providing a low-carbon and efficient technical solution for large-scale cross-regional transmission of renewable energy.