As the technology based on the Fourth Industrial Revolution is applied to the power industry, the digital transformation of the power industry is proceeding. The energy production – power generation, transmission, and distribution – customers are going through the entire value chain in the power industry. This study aims to establish a proper strategy by analyzing the trends of fusion and innovation of the core technologies of digital transformation within the power industry through a patent analysis of the Korea Electric Power Corporation (KEPCO) and its subsidiaries, which cover all fields of the Korean power industry due to its monopoly. Through a literature review, we derived two research hypotheses on the effect of the powerdigital transformation technology fusion. This study analyzed 9,669 power industry patents over 20 years from 1998 to 2018 and examined the influence of the core technologies of digital transformation (AI, Big data, IoT, Cloud) through the network analysis method. It then investigated the effects on the power industry through multiple regression analysis. The results of this study are as follows. First, there was high betweenness centrality leading convergence in the power industry regarding Big data, AI, Cloud, and IoT, in this order. Second, through regression analysis with power loss rate, which is determined to evaluate power plant operation efficiency activities, we found that connectivity of IoT technology has a significant negative correlation with power efficiency. This study will enable the establishment of appropriate policy directions for the future power industry and a comparative analysis of the degree of homogeneity and heterogeneity by creating a digital transformation index.