Operating capability of long AC EHV transmission cables

The operating constraints involved in power transmission of long AC cable links are presented and here throughout developed. The possibility of transmitting high power rating is examined and the transmission length limits are evaluated. The procedure, which uses the great computation and graphical facilities of modern computers, is essentially based on the classical transmission equations and their pertaining diagrams. It has been particularly applied to XLPE cables and gas-insulated lines but it is worth applying to any distributed-parameter transmission line (including overhead lines). The capability chart proposed in the paper is a useful tool to highlight the operating characteristics of a cable link and a guide to evaluate the results of different degrees of reactive compensation. The authors hope that the results can offer the transmission system operators very effective means in order to evaluate the existing and future underground cable links.