The rapid increase in the installed power of generators supplying the low voltage distribution network (for example photovoltaic and cogeneration systems) requires innovative solutions at the interface between the electrical installation and the network. A project group in the FNN involving all the expert groups affected has prepared a VDE regulation with the objective of integrating decentralized power generators better in the power supply network through standardized technical requirements.
In Germany, photovoltaic systems alone are currently feeding nominal power of about 14 GW into the low voltage distribution network. This high proportion meanwhile has significant relevance for network and system technology.
The VDE application guide first defines basic requirements for a so-called "symmetrical three-phase current infeed" from generators, in particular from inverter-based generators.
Through the targeted provision of reactive power, generators in the low voltage distribution network are to contribute towards static voltage stability in future.
The VDE application guide also describes requirements to be met by a frequency-dependent active power control, in order to guarantee in particular system stability in the event of overfrequency (see "50.2 Hz problem"). The objective is to guarantee safe and reliable network and system operation with a high power supply quality.
The VDE application guide takes effect as of 1 August 2011. Transitional periods are provided for at the beginning of the application to facilitate its implementation and introduction for all those involved. For photovoltaic systems in the low voltage distribution network, the application guide will become binding on 1.1.2012, and on 1.7.2012 for all other generators in the low voltage distribution network. The VDE application guide is intended to become an integral part of the technical connection conditions for network operators. The use of VDE-AR-N 4105 provides a reliable standard that gives all parties a good basis for action and planning.
A summary of the most important facts:
- VDE regulation facilitates network integration of decentralized generators
- The core of VDE-AR-N 4105 is network-supporting functionality to guarantee safe and reliable network operation for maximum integration of generating capacity in the low voltage distribution network
- Transitional periods: Photovoltaic systems in the low voltage distribution network 1.1.2012, other generators in the low voltage distribution network 1.7.2012
- VDE-AR-N 4105 is intended to be a component part of the technical connection conditions (TAB) of a network operator
- This technical standard provides a more reliable basis for planning, investment and action.