Analytical solution and scaled model of a unipolar HVDC transmission line

Existing analytical solutions for the ionized field of a unipolar HVDC transmission line are reviewed. The analytical relations indicate that the corona current is directly proportional to the square of the corona onset field strength if the ratio of the applied voltage to the corona onset value and that of the conductor height to its radius remain fixed. This is confirmed by numerical results. It is pointed out that this observation makes it possible to derive the basis of a scaled model to evaluate the corona current and hence the resulting power loss of a full-scale unipolar DC line