Overview of the electromagnetic environment in the vicinity of HVDC transmission lines

The purpose of this paper is twofold. Firstly, an overview of the interaction between High Voltage Direct Current transmission lines and the environment they are operated in is presented. Secondly, the equipment required to characterise this environment is discussed. There is a need to understand the environmental effects of transmission lines due to regulations involved in new line design. General effects of both high voltage alternating current and high voltage direct current overhead transmission lines are provided. The effects of electric field and ions are of interest to this paper and are therefore described in detail. Specialised instruments that are required to measure the electric field strength, ion current and space charge density at ground level in the vicinity of the line are discussed. These instruments need to be calibrated in an environment that emulates the one in the vicinity of the transmission lines. A field calibration chamber for such a purpose is presented. The paper concludes with a description of a framework for carrying out research to characterise the electromagnetic environment in the vicinity of high voltage direct current transmission lines. This research framework consists of both laboratory and field studies and also the general perceived contributions of such research.