Smart Grid - energy distribution and network control

Regulating everything for the turnaround in energy policy – controllable local network transformers

Ront concept: the smart active transfomer
With an increasingly decentralised electricity supply from renewable energy sources, regional distribution networks face higher demands with regard to flexibility and capacity. Controllable local network transformers (“Regelbare Ortsnetztransformatoren”, or RONT) are a more effective and cost-saving solution than network expansion for the purpose of activating existing reserves on a medium- and low-voltage level. With the SmartActiveTransformer, J. Schneider Elektrotechnik GmbH has developed its own RONT concept within the framework of a research project.

The German energy landscape is undergoing a fundamental change: while electricity previously flowed from the power plant to the consumer, there is now an increased frequency of high-voltage fluctuations in the distribution networks due to the growing number of decentralised producers who feed their electricity at the medium- and low-voltage level. There is a particular risk of exceeding the permissible voltage tolerances in small meshed networks in rural areas.

In order to maintain these tolerances and those of high supply levels, a massive network expansion which is expensive and time-consuming would be necessary. The use of controllable transformers instead of the common unregulated transformers of today could provide short-term relief. By decoupling the rigidly connected medium- and low-voltage networks, the capacity of the two networks would significantly increase. Furthermore, a corresponding reduced network expansion would make it possible to save billions of euros.

An operational product which meets the high requirements of the energy industry is already available: as part of a research project[1]), J. Schneider Elektrotechnik developed the SmartActiveTransformer. An electromechanical vacuum switch in reactor technology which is integrated into the transformer tank guarantees the required 30 years of maintenance-free operation. The dimensions of the SmartActiveTransformers correspond to those of an unregulated transformer, making a simple exchange in the transformer station possible. Another advantage is its black-start capability, i.e. after a voltage interruption, the transformer is immediately ready for operation without auxiliary energy.

Important building block for the turnaround in energy policy
While in operation, the SmartActiveTransformer continuously measures the voltage on the low-voltage rail and independently selects the ideal switch position. Nine load levels enable a control range of up to 24%. Field tests have shown that in this manner, the potential for recording feeds in both the medium- and low-voltage network increases threefold. This makes the SmartActiveTransformer an important building block for increasing the flexibility of electricity grids and thus the success of the turnaround in energy policy.

[1] “Funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety as based on a decision by the German Bundestag”


contact details/company:
J. Schneider Elektrotechnik GmbH
Helmholtzstraße 13
77652 Offenburg

contact person:
Georg Litterst