• Project to demonstrate grid stability with high proportion of variable renewable
• Smart meters adapted to operate as low voltage sensors

Power Lines

Krefeld and Nuremberg, Germany --- (METERING.COM) --- November 27, 2012 - The North Rhine-Westphalia municipal utility SWK Stadtwerke Krefeld AG is working with Siemens to transform the existing power supply system in Wachtendonk on the Lower Rhine in Germany into a smart grid for research and testing purposes.

Siemens will supply the necessary components for the smart secondary substations, smart meters, as well as measuring, monitoring, and communication technology. SWK will combine these individual components into a smart system and test them in specially selected low voltage networks.

Other goals include developing and securing a data transmission system from the network to the SWK control center, and testing the applicability of technical components in everyday use in order to obtain insights useful for the further development of the smart grid.

Through this project, detailed information will be acquired about the behavior of a distribution network with a disproportionately high number of renewable energy sources – as expected to occur under Germany’s “energy transition,” when the number of private producers feeding power into the grids will increase significantly.

“The project name ‘Wachtendonkmachtmit: ForschungimNetz’ (‘Wachtedonk is doing its part – Researching the grid’) reflects the role Wachtendonk is playing in the development of the smart grid,” commented Carsten Liedtke, chairman of the Board of Stadtwerke Krefeld. “We are proud to be playing an active part that will help shape Germany’s new energy policy and make the power supply system fit for the future.”

The 8,000-strong community of Wachtendonk in the Kleve district was selected as the smart grid model region because it has a very high proportion of distributed power generation plants that feed into the grid. About 80 percent of its electricity comes from renewable energy sources such as roof-mounted photovoltaic plants. In addition, the effects resulting from decentralized power feeds will become more evident in the rural power network.

As part of the project, smart meters will be installed in 100 homes and in numerous cable distribution boxes. For this purpose, Siemens has equipped its smart meters with an add-on function through which data relating to the network status can be recorded and forwarded. The so-called power snapshot analysis allows “snapshots” to be taken of the otherwise “blind” low voltage system in the form of synchronous network parameters. This enables the meters to also operate as low voltage sensors that deliver data that will be used to analyze the power distribution grid in Wachtendonk, in order to improve the stability and transparency of the grid.

As soon as a specific threshold is exceeded or undershot, the smart meters transmit the network data via powerlines to the secondary substation and from there to SWK so that countermeasures respectively stabilization can be immediately initiated. Five smart secondary substations with controllable distribution transformers from Siemens are also used to stabilize the network. These controllable distribution transformers use realtime data from the lowvoltage system measured by the smart meters as control variable and then dynamically adapt the voltage conditions in the local network.

While cabling the entire system of medium and low voltage overhead line, which will be completed by 2014, SWK NETZE GmbH also laid empty conduits so that there are now 22 substations equipped with fiberoptic transmission equipment and connected to SWK’s control center in Krefeld. 52 of the 105 secondary substations have already been modernized and are ready to be equipped with smart grid components. This will make it possible to upgrade these substations to form the core of a smart secondary distribution network without a great investment of cost or effort.