Power systems around the world are faced with a wide range of challenges in order to realize the objective to integrate an increased amount of renewable energy sources in the modern electricity grids. The consequences affect the daily operation and longterm planning of transmission and distribution systems, and the network owners and operator’s ability to ensure continuous, reliable and high quality of supply to the customers. The needs of each actor within the electrical supply chain provide drivers for revision of current practices and promotes future adaptions of functional components and systems, economic and regulatory areas. In this document, we describe the drivers for change regarding generation, demand, and grid, the resulting consequences this has on operation and planning of the power transmission and distribution systems, and finally the needs to ensure sustainability & security of supply from the technology, market and policy perspectives.