Geophysical and geological pre-investigations for HVDC-electrodes

The potential differences caused by the current injected in the ground by a HVDC-electrode can cause corrosion of e.g. pipelines and operational problems in transformer stations. Also, hazardous electric fields can arise in the vicinity of HVDC-electrodes. High potentials and strong fields from electrodes are, in principle, related to high-resistivity rock in the ground The presence of such potentially problematic rock volumes is not routinely checked before the construction of an electrode site. However, geophysical methods are available that can estimate the electrical properties of the bedrock down to considerable depths. Such surveys, in combination with geological knowledge and modeling can be used to predict the environmental impact of an electrode.