What key technologies need to be researched to build UHV DC transmission lines?

Compared with AC overhead lines, there is no significant difference in the design and calculation of mechanical structure between DC overhead lines and AC overhead lines. But on the electrical side, there are many different characteristics that require specialized research. For the construction of UHV DC transmission lines, special attention needs to be paid to the following three aspects of research:

1. Corona effect

Under normal operation conditions, DC transmission lines allow a certain degree of corona discharge in conductors, which will produce corona losses, electric field effects, radio interference and audible noise, etc., resulting in operational losses and environmental impacts of DC transmission. Due to the high voltage of UHV projects, if not properly designed, the corona effect may be greater than that of UHV projects. Through research on the corona characteristics of UHV DC, we can rationally select wire types, insulator strings, and hardware assembly types to reduce corona effects, reduce operating losses, and impact on the environment.

2. Insulation coordination

The insulation coordination of DC transmission projects has a great impact on the investment and operation level of the project. Due to the "electrostatic dust collection effect" of DC transmission, the pollution accumulation and pollution flashover characteristics of insulators are very different from those of AC. The resulting pollution discharge is more serious than that of AC. Reasonable selection of the insulation coordination of DC lines is important for improving operation Level is very important. Since UHV DC transmission is the first of its kind in the world, the existing test data and research results at home and abroad are very limited. Therefore, it is necessary to conduct in-depth research on the insulation coordination issues of UHV DC transmission.

3. Impact of electromagnetic environment

The use of UHV DC power transmission is undoubtedly of great significance for achieving optimal allocation of resources on a larger scale, improving the utilization rate of transmission corridors and protecting the environment. However, compared with ultra-high voltage projects, UHV DC transmission projects have the characteristics of high voltage, large conductors, tall towers, and wide single-circuit line corridors. Its electromagnetic environment is somewhat different from that of ±500 kV DC lines, which brings The environmental impact will inevitably attract the attention of all sectors of society. At the same time, the electromagnetic environment of UHV DC projects is closely related to wire types, wiring heights, etc. Therefore, careful study of the electromagnetic environmental impact of UHV DC transmission is crucial for project construction to meet environmental protection requirements and reduce construction costs.

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