For a University project I need to somehow model the effective performance of a ground grid in the event of a fault caused by a lightning strike. We would need to prepare different test cases for different sizes and grid configurations in order to carry out different analysis and find the optimal performance point. So far the only software that I know that is capable of carrying out these computations is the HIFREQ software module from SES Technologies. However, the cost of an educational license is way beyond our budget. Does anyone know of any alternatives that are open-source software or have very cheap educational licenses (below $1k per license)? Any help is appreciated.