ultrahighvoltage

Ultrahigh voltage (UHV) is a class of electrical transmission voltages typically defined as voltages of 1000 kV (1 MV) and above. In alternating current (AC) systems, UHV commonly refers to 1000 kV to around 1100–1500 kV, while in direct current (DC) systems, voltages designated as ultrahigh voltage are generally 800 kV DC or higher. UHV is used for bulk power transmission over long distances and for interconnecting large regional grids or remote generation sources.

Advantages of UHV include increasing the transmission voltage to reduce current for a given power, which lowers resistive (I^2R) losses and allows longer interconnections with fewer conductors and towers. It enables economical cross-border links, integration of distant renewable resources, and underwater cables.

Technical challenges of UHV require advanced insulation coordination, long-duration creepage distances, and robust equipment capable of handling high electric stresses. Corona discharge, partial discharge, switching overvoltages, and lightning can be more severe. Specialized equipment such as robust transformers, reactors, converter valves for HVDC, surge arresters, and precise grid protection and control is essential. Maintenance costs are higher, and the risk of insulation failure must be mitigated.

Applications and deployment: UHV is widely used in large economies with long-distance transmission needs, notably in China and some parts of Europe and Russia, for HV AC and HVDC links to move power from generation centers to population centers and to connect grids. Notable implementations include 1000 kV-class AC lines and 800 kV+ DC links.

Standards and research: Engineering standards for insulation coordination, clearances, and equipment ratings exist under regional standard bodies (IEC, CENELEC, IEEE). Ongoing research focuses on materials, corona suppression, grid integration, and reliability.