The current stage of world energy development is characterized by the creation of powerful, territorially unified energy systems under free market conditions as well as renewable energy integration. Such transactions challenge networks’ configurations and their operating modes. Electric power system (EPS) static stability could be considered one of the primary targets in this regard. The aim of this study was to evaluate the undergoing and expected modernization of the Latvian EPS in terms of static stability in a regional scale-based case study. In order to define static stability, a method based on a bus admittance matrix was proposed. A simplified Latvian EPS model was developed and assessed for the following three modes: past (2017), current (2020), and planned (2025), taking into account the Baltic States’ planned development scenarios including large wind farm integration. The evaluation of computation results provided an opportunity to visually inspect changes in the EPS’ sensitive elements such as lines and nodes. As a result, positive changes were observed (decrease of several weak points) for the planned mode (2025) as compared to the past mode (2017) under the considered modernization scenario. The detailed analysis and results are presented in the article.