Integration of renewable and dispersed resources: lessons learnt from German projects

In particular, the installation of renewable decentralized energy sources in the distribution system will increase the importance of this subsystem in future power system operation. The secure operation of a power system depends on the provision of system services such as frequency stability, power balance, voltage stability or system management. The current responsibilities for these system services will be discussed in this paper taking into account German experiences using decentralized energy sources. Furthermore, some guide lines on planning and operation, which take into account the impact of this new situation as well as recent experiences in Germany, was discussed. The following topics were elaborated and described: decentralized energy management, reserve power provision, coordination with a transmission system operator (TSO); voltage stability; fault ride through and supply restoration; power balance in island operation. The description takes into account the modeling issues, the operation of the wind parks, the planning and operation of the dispersed generation and will lead to a proposal of a benchmark for the medium voltage network. Finally, a general conclusion and recommendations for future development were given