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Network sensors in the local network stations and cable distributors record all relevant quality parameters. The data is transmitted via the dedicated fibre optic network or GPRS.
© Stadtwerke Saarlouis GmbH
Medium- and low-voltage networks

In PolyEnergyNet, autonomous sub-networks (holons) have been developed that can dynamically adapt to the respective network situation in order to achieve an optimal supply situation.
© Stadtwerke Saarlouis GmbH

A central control centre is connected to the holon control elements.
© Stadtwerke Saarlouis GmbH

Resilient poly-networks were realised and tested in the field test area belonging to Saarlouis municipal utility company.
© Stadtwerke Saarlouis GmbH

Local electricity networks become flexible and resilient

For three years, the Saarlouis municipal utility company, together with partners from science and industry, has worked on the development of what are known as resilient poly-networks. These autonomous electricity networks at the local level are designed to adapt dynamically to the respective network situation in order to ensure optimum supply. The findings were recently presented at a concluding event.

As the share of renewable energies in the power generation increases, instabilities in the electricity grid can also occur more frequently owing to intermittent loads or the rapid loss of power from generators, for example as a result of equipment overloads on transformers or transmission lines. Automation is already well advanced at the transmission network level. However, the control and regulation requirements will increase in future at the local level, i.e. for the operation of the medium- and low-voltage networks.

Imbalances between production and consumption are caused by weather-dependent grid feed-ins and unexpected network loads. Their balance already needs to be taken into account at the local network level in order to avoid the need for expansion with expensive transmission lines. This is where the PolyEnergyNet research project comes into play. The aim is to research and develop resilient local networks, i.e. local networks that respond as resiliently as possible to disruptions and critical supply situations. This is because a robust network operation can respond to both the volatility of the decentralised renewable energy fed into the grid as well as to unforeseen events that even include cyber attacks.

Poly-networks and holon sub-networks

The project solutions adopted can be identified by two terms: poly-networks and holon sub-networks. Poly-networks are individual energy networks linked by means of transfer technologies. These therefore form an overall network controlled by information technology. With holon sub-networks or holons, the researchers envisage the formation of dynamic micro-grids that control the distribution of locally generated electricity from renewable energy sources or cogeneration plants to the loads. These provide the germ cell for a future smart grid and enable climate-friendly power generation on the ground.

In PolyEnergyNet, the researchers have developed autonomous sub-networks that can dynamically adapt to intermittent network loads. In addition, the energy networks were linked via the fibre optic network to enable energy to be automated transferred. The project consortium believes that this has created new impetus for the development of an intelligent and sustainable energy provision.

Field test with the Saarlouis municipal utility company

Based on the theoretical preliminary work, resilient poly-networks were implemented by way of example as part of a field test in the network belonging to the Saarlouis municipal utility company. The test system enabled the decentrally generated energy to be consumed directly on the ground or converted for different uses. The formation of new holons enabled an optimal supply situation to be achieved. In the test area there is a local heating network that supplies several residential buildings via a central gas heating system that in turn is fed by the gas network belonging to the Saarlouis municipal utility company. The electrical supply network is supplied by six medium-voltage stations and around 20 photovoltaic installations.

The low-voltage connection of the local network stations makes it possible to allocate generators and loads to different holons as required. The grid topology can be adapted to different supply situations and grid conditions via disconnect points in cable distribution cabinets.

Further information on the project final report as well as the presentations held at the concluding event can be found on the polyenergynet.de website.



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Project coordinator and electricity network operator
Stadtwerke Saarlouis GmbH


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