VDE|FNN definiert mit Anwendungsregel „Planungsgrundsätze für 110-kV-Netze“ erstmals Planungsgrundsätze für die Hochspannung

Design principles for 110 kV networks (VDE-AR-N 4121)

The Application Rule "Planning principles for 110 kV grids" (VDE-AR-N 4121) ensures technically and economically sustainable grid expansion in the high-voltage range.

In a nutshell

  •  For the first time nationwide uniform planning principles for high-voltage networks
  • Planning horizon greater than ten years
  • Application of the NOVA principle: network optimisation before reinforcement and expansion
  • (n-1)-safe planning: failure of a piece of equipment must not lead to inadmissible operating condition

The VDE-Application Rule "Planning principles for 110 kV networks" (VDE-AR-N 4121) defines for the first time nationwide uniform procedures and assumptions for the planning of high-voltage networks. The Application Rule lays down important principles for planning and thus facilitates the work of network operators. Each network operator is responsible for the concrete implementation and economic optimization of the network and its operation.

Focus on long-term planning

The Application Rule focuses on the technically and economically sustainable planning of high-voltage networks with a planning horizon of more than ten years. The main steps of the planning process are described as well as the principles behind them.

The grid is dimensioned based on forecast developments in load and generation. If the planning shows that the supply is at risk, measures are implemented according to the NOVA principle: first, an attempt is made to optimize the grid (e.g. by switching circuits) before the grid is reinforced (e.g. changing cables) or expanded as a last measure.

The aim of planning is to ensure that the failure of a piece of equipment does not lead to inadmissible operating conditions under any circumstances. This planning principle is called (n-1) safety. In addition, special failure scenarios are defined in the Application Rule, for which even the simultaneous failure of several pieces of equipment must be considered.

Publication date


Shiqi Wang
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Applying active concepts sensibly

In addition to the classic methods of network optimization, such as line reinforcement or new construction, active concepts are increasingly being considered in network planning. Active concepts are understood as the situation-dependent influencing of network operating variables (e.g. power flow, voltage) in order not to violate the thermal load capacity of the equipment and the voltage allowance bands. In this way, the existing infrastructure can be better utilized and possible network expansion requirements can be reduced. Examples of active concepts are weather-dependent overhead line operation, the use of redispatch during planning (“Spitzenkappung”) or load management.

The Application Rule is part of the activities of VDE FNN to prepare the system for the increasing feed-in of renewable energies as part of the energy transition.

Target groups

  • Network operator
  • Planning offices
  • Approval authorities

Benefits and improvement

In many regions of Germany, the expansion of renewable energies means that existing distribution networks also need to be strengthened or expanded at the high-voltage level. The aim here is a technically and economically sustainable high-voltage grid. Efficient network planning can reduce costs and help to increase supply reliability. Early consideration of the connection of renewable plants in network planning facilitates the integration of renewable energies.