Smart meter used as “eyes in the grid”Smart Grid in model region Wachtendonk, Niederrhein
“The turnaround in energy policy begins at home. As municipal energy providers, the public utility companies promote this idea,” said Carsten Liedtke, spokesperson for Stadtwerke Krefeld (SWK), at the start of the Wachtendonk smart grid project. “However, this turnaround cannot be realised without smart grids. For this, the power distribution grids must be more intelligently and further automated,” adds Karlheinz Kronen, CEO of the Energy Automation business unit of the Siemens Smart Grid Division. For these reasons, the two companies have decided to turn the existing power network of Wachtendonk, a community of about 8,000 inhabitants, into a smart grid for research and testing purposes.
Wachtendonk was selected as a smart grid model region because more than 80% of the community’s electrical power already comes from renewable energy sources such as photovoltaic systems on rooftops. However, this isn’t happening without known side effects. The impact of the volatile decentralised supply has been noticeable on Wachtendonk’s rural power grid for some time: instabilities from current fluctuation are not uncommon. The future smart grid will remedy this. Siemens is supplying the necessary components for the intelligent local network stations, intelligent meters as well as the necessary measuring, monitoring and communication technology. SWK link these components to an intelligent energy system and test it in selected sections of the low-voltage grid. In addition, the data transmission is extended to the SWK control centre. Over the course of the project, Siemens and Stadtwerke Krefeld will compile detailed information about the behaviour of a power distribution network with a disproportionate amount of renewable energy sources. The aim is to test the practicality of the applied technique in order to acquire knowledge for the development of smart grids in other service areas.
As a result, about 100 households and numerous low-voltage distribution boards will have smart meters installed. These meters will capture the required network status data for the operation of an intelligent grid. Siemens has also had its smart meter equipped with a special extra function. This power-snapshot analysis allows “snapshots” in the form of key network parameters from the otherwise “blind” low-voltage grid. For this reason, the smart meters operate as low-voltage sensors – almost like eyes in the grid. They provide the data for an analysis of the Wachtendonk power distribution network, to create the pre-conditions for a smart grid and to improve the stability and transparency of the network.
Five new intelligent secondary substations also provide more stability. Amongst other things, these stations balance out voltage dips that result when a wall of clouds sits above the solar panels on the roofs. The substations are equipped with medium-voltage switchgear capable of communicating, regulated distribution-transformers as well as remote operation and distribution grid automation components. Of the 105 existing secondary substations in the township, 52 have already been renovated and prepared to house smart grid components. Wachtendonk has taken a leading role when it comes to testing smart grids under real conditions. As a "smart city", Wachtendonk will not only contribute to the success of the turnaround in energy policy, but it will also help shape the future of a smart grid in Germany.