This paper deals with the problem of planning operations in distribution networks with a high penetration of distributed energy sources. It presents and describes the distributed energy sources present in Croatia, the reasons for introducing distributed generation, and the technical requirements for their connection to the grid. The transition from passive to active distribution networks is illustrated, along with the integration of active distribution networks and a comparison between passive and active distribution networks. Asset management and asset maintenance strategies are described, along with the challenges faced by asset managers. An overview of energy storage systems is provided, as well as a review of electric vehicle charging methods, their integration into the grid, and their impact on power quality. Strategies for operating distribution networks with integrated distributed sources, including demand response, microgrids, and virtual power plants, are discussed and analyzed. The advantages of demand response, microgrids, and virtual power plants in the context of active distribution networks are examined. The final section of the paper describes traditional planning and highlights the reasons for its inadequacy, presents a general framework for planning active distribution systems, and outlines the steps for its implementation. Finally, a case study of a new planning approach is presented.