A parallel galerkin's moment based method for finding resistance of HVDC grounding electrode

High Voltage Direct Current transmission has been used for transmitting a large amount of electric power over long distances. Among different modes of HVDC operation, mono polar and homopolar HVDC operations require ground as the return path. Hence accurate estimation of grounding resistance is a key design aspect in those HVDC operations. The main objective of the present work is to formulate a method for computing the grounding electrode's resistance on uniform soil using Galerkin method of moments. Both testing and basis functions are taken as pulse function instead of a delta function, which makes the method variational and results in a very small error with a substantial saving in computation effort. The effect of air-soil interface is modelled by using the method of images. The resistance of some of the commonly used grounding electrodes in HVDC operation such as star, ring and vertically driven rod are evaluated using the present method. The system matrix is then computed and processed in parallel and solved using parallel conjugate gradient method to make the algorithm efficient in time. The accuracy of the present method and improvement of time efficiency in parallel processing compared to sequential processing is also discussed in the paper.