Optimal reactive power supply in distribution networks - technological and economic assessment for PV-systems

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 3872-3881
As a reaction to the steadily increasing share of photovoltaic (PV) power, German utilities are working on a new standard for the connection and parallel operation of generators in low voltage networks. The new grid code could be a big step towards active participation of PV-Systems in low voltage network operation. Reactive power provision by PV systems is expected to be interesting in future. This paper starts with a theoretical introduction on how reactive power can be used to influence of PV power feed-in on the voltage at its point of common coupling. For a technical and economical optimization of the most common reactive power provision methods two typical German low voltage distribution test feeders (rural and suburban network structure) with high level PV penetration have been modelled and analyzed. Here, the economic evaluation considers the perspective of the PV plant operators as well as of the distribution system operator. The results show that the highest share of the total additional operational costs arises for the PV plant operators and that there exists a big difference in the costs of the different reactive power supply approaches. Also an overview is given about the actual situation on grid codes and the certification procedures in Germany.