Increasing power consumption and reliance on non-predictable renewable power generation is pushing the transition from analog to digital power grid substations forward. Grid digitalization helps to reduce substation complexity and therefore costs, and improves observability and management, but introduces new cyber security issues. To make the digital substations secure, cyber security awareness and efficient personnel training is one of the most important research areas as the power grid is a part of critical infrastructure. In our previous work, we have proposed an approach for analyzing cyber security threats and attacks in digital substations based on a case study from Norway. In this article, we present how we developed a tool for emulation of digital substation communication for cyber security awareness based on experiences from the case study. We present technical details of the tool—called the SGSim—so the community can easily replicate the process or only the selected parts. We also freely provide source code on GitHub and distribution in the form of a virtual machine on request. Finally, we validate the tool performance in several scenarios and evaluate its usability on a survey conducted among a wide range of professionals.