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In this work, a method to compute the radio interference (RI) lateral profiles generated by corona discharge in high voltage direct current (HVDC) transmission lines is presented. The method is based on a transmission line model that considers the skin effect, through the concept of complex penetration depth, in the conductors and in the ground plane. The attenuation constants are determined from the line parameters and the bipolar system is decoupled by using modal decomposition theory. As application cases, ±500 and ±600 kV bipolar transmission lines were analyzed. Afterwards, parametric sweeps of five variables that affect the RI levels are presented. Both the RI and the maximum electric field were calculated as a function of sub-conductor radius, bundle spacing, and the number of sub-conductors in the bundle. Additionally, the RI levels were also calculated as a function of the soil resistivity, and the RIV (radio interference voltage) frequency. Following this, vector optimization was applied to minimize the RI levels produced by the HVDC lines and differences between the designs with nominal and optimal values are discussed. [ABSTRACT FROM AUTHOR]

This study presents the influence of corona rings on impulse withstand performance of 380 kV V-insulator strings. Those strings comprising cap-and-pin type glass insulator units are one of the most common configurations in Turkish National Power Transmission System. Laboratory test setup was constructed for the centre phase of a full scaled tower. Laboratory tests are performed to investigate the lightning and switching impulse performance of the strings equipped with the existing racket type corona rings and the circular type corona rings. Withstand voltages, lower flashover probability levels, flashover routes and times to flashovers are determined under dry and wet test conditions. In addition, some 3D field simulations regarding potential and electric field distributions are also performed for the interpretation of insulator surface flashovers. [ABSTRACT FROM AUTHOR]

This paper presents corona ring optimization for 380 kV V-insulator string composed of glass insulator units. The influence of the corona ring design parameters are examined not only with regard to 3D simulations but also laboratory tests. The purpose of the simulations is to find reasonable corona ring design parameters such as corona ring diameter, corona tube diameter and installation height on the point of effective field regulation around the critical region of the string. Indoor laboratory tests including radio interference voltage levels, corona inception voltages and ac flashover voltages are conducted on the centre phase of a full scaled tower both for experimental based corona ring design as well as verifications of the simulations. After both simulations and experimental based investigations, appropriate corona ring design parameters for the string are determined for effective field regulation, minimum interference level, ac flashover performance and economic point of view. [ABSTRACT FROM AUTHOR]