Power systems are one of the critical infrastructures that has seen an increase in cyber security threats due to digitalization. The digitalization also affects the size and complexity of the infrastructure and therefore makes it more difficult to gain an overview in order to secure the entire power system from attackers. One method of how to gain an overview of possible vulnerabilities and security threats is to use threat modeling. In threat modeling, information regarding the vulnerabilities and possible attacks of power systems is required to create an accurate and useful model. There are several different sources for this information. In this paper we conduct a systematic literature review to find which information sources that have been used in power system threat modeling research. Six different information sources were found: expert knowledge, logs & alerts, previous research, system’s state, vulnerability scoring & databases, and vulnerability scanners.