The interaction between DSO and TSO to increase DG penetration — The Portuguese example

The operation of transmission networks is made depending on their loads - distribution system. Transmission systems are optimized to ensure loads and generation from EHV, HV and MV. The connection of DG units to distribution networks can impact the planning and operation of transmission systems. When these units are predominantly from renewable sources, given their intermittency or derived from disturbances, they may temporarily disappear causing potential problems on the balance between loads and generation. This paper addresses the challenges that DG units may cause on distribution and transmission networks and, hence, the need for information exchange between DSO and TSO. An example of a real implementation is detailed and the quantity and type of information valuable for both system operators is explained.