Numerical Computation of Electric Field Distribution for HVDC Systems at R&D Facilities

High voltage technology is widely used all over the world at various R&D facilities for development of pulse power generators, particle accelerators, X-ray generators, neutral beam injectors, etc. An UHVDC laboratory consisting of 600 kV Cockcroft-Walton generator, 750 and 300 kV voltage dividers, 500 kV load banks, 200 kV transformer-rectifier units and power converters have also been recently installed at the Institute For Plasma Research (IPR), Gandhinagar, for nuclear fusion research and particle accelerator innovations. An accurate electric field prediction is pivotal for design and fabrication of any HVDC apparatuses for avoiding partial discharges and is also indispensable with regard to human safety and electromagnetic interferences (EMI). This paper involves electric field analysis of air-insulated HVDC systems with respect to corona ring design and ground clearance for HV generators, dividers, load banks and transmission lines. Various tools are available nowadays for high voltage field calculations such as the finite element method (FEM), charge simulation method (CSM), etc. However, each method has its own pros and cons. Here, for different corona ring configurations, CSM has been employed in this paper, and a MATLAB code has been developed for electric field and ion current density estimation at ground level for HVDC transmission wires and compared with experimental results. The techniques employed have been highly useful for development of HV facilities at IPR.