The construction of an ultra-high voltage (UHV) national grid to achieve optimal allocation of energy resources is an important goal and task for power grid development. It holds great significance in ensuring the safe and stable operation of power sources and grids. Countries such as the United States, Canada, Russia, Japan, Italy, and Spain have been researching UHV transmission technology for over 40 years since the 1970s.
Over the last 30 to 40 years, several blackouts in Europe and North America have highlighted the risks associated with high load supply and large coverage areas in AC power systems. To address these risks, it is important to establish a well-connected UHV AC grid that can provide ample spare capacity. The grid is susceptible to natural disasters like typhoons, rainstorms, lightning strikes, and ice storms, as well as man-made disasters such as military sabotage. Without sufficient spare capacity, accidents can quickly propagate.
To ensure the safe operation of the grid, it is necessary to study the grid structure in terms of planning, design, construction, and operation. Implementing three levels of protection, stratification, and zoning are essential principles. The State Grid and the Southern Power Grid have proposed the construction of an extra-high voltage national grid to optimize the allocation of energy resources.