The Simris energy system is one of six industry-scale demonstrators in the InterFlex EU project.

The technology behind

Dive deeper into local energy system technology.

Renewable electricity production

The production of electricity in the local energy system will be one hundred percent renewable. It will come from three different types of production sources – wind, solar cells and a backup power generator powered by renewable fuel.

Wind turbines

Most of the electricity production in a local energy system usually comes from a wind turbine. A wind turbine with a nominal power of 660 kW can produce between 1.1 and 1.5 GWh annually.

Solar cells

E.ON is convinced that solar power plays an important role for the energy systems of the future. Therefore, these form a natural part of the local energy system. Micro production from solar panels on roofs becomes increasingly relevant. To create a system that is as real as possible, we hope that more customers will want to install solar cells on their roofs.

Backup power generator

Since both sun and wind are intermittent* energy sources, they will need support in the form of adjustable electricity production. A backup power generator is installed to provide this when the energy system is in “island mode”. When the local energy system is not in operation, the central grid will supply the electricity that is not produced locally. The backup power generator runs on HVO (Hydrogenated Vegetable Oil) Diesel 100, a renewable diesel fuel. HVO Diesel 100 uses 100 % renewable material – more specifically, slaughterhouse waste. HVO Diesel 100 is chemically more or less identical with fossil diesel.

*Intermittent = something that only occurs once in a while and which at times is interrupted.

Battery for energy storage

The battery for energy storage can be seen as the heart of the energy system. Together with an advanced control system, the battery will ensure a correct voltage and frequency within the local grid. It will add or emit energy to make sure the system stays in balance.

In order for the components connected to the local grid to function, the frequency needs to be kept at 50 Hz at all times, with a maximum deviation of 0.5 Hz upwards or downwards. To be able to keep this balance, it is important that the battery is neither fully charged nor completely empty. The control system sees to this. The battery and control system will also ensure that connecting to and from the central grid works as it should. When connecting or disconnecting, the grids must be synchronized. The battery will control voltage, frequency and phase angle to make sure the transition runs smoothly.

The battery system plays a very important role for a local electricity grid using renewable and intermittent energy sources. Grid balance at all times is a prerequisite for good power quality around the clock.

The control system is the brain of the system

A sophisticated control system is the brain of the local energy system. It will ensure that all production units can communicate with each other and deliver good quality electricity at all times. The automatic control equipment controls the frequency of the local grid, keeping it at the required 50 Hz. It also makes sure that the correct voltage and phase angle is maintained. Everything is carried out in close collaboration with the battery system – the so-called "grid-forming unit". This means that the battery is the source for instant adjustment if consumption increases or decreases.

The control equipment will give information about the instantaneous production from each unit in the local energy system, which means that it is possible to see exactly where the electricity is produced at any given time. This information will greatly benefit those who work with and analyse the system. But the information can also be provided to customers interested in the local production of electricity.

RTU – the dispatch central for the primary substation

A Netcon 500 RTU (Remote Terminal Unit) is located at the primary substation. It communicates continuously with the primary substation equipment, transforms indicator signals and protocols, clocks all events and sends the information to the network operating centre.

When there is a signal from the network operating centre, this is transformed to an electric contact closure, which for example controls switches and disconnectors in the primary substation, or adjusts the ratio in a transformer. It also has a built-in firewall and ensures that upstream communication is encrypted for maximum data security.


The DER station – the hub in the local energy system

The inside of a substation, also known as a DER station (Distributed Energy Resources), functions as a hub in the distribution network. The substation is a prefab building, cost-efficiently tailored for the customer and this particular purpose. The design is robust, and the exterior is built without any organic materials to ensure a long lifespan.

The substation functions as a hub in the local energy system, where the electric energy flows in different directions – from production and storage to consumption. The substation includes medium voltage switchgear with relay and control, a distribution transformer, voltage transformers for measurements, grid automation equipment and the advanced control system – the brain of the local energy system.

The customers’ electricity usage

It is generally a big challenge for micro grids to accommodate maximum output on the local grid, something that only occurs on rare occasions. For customers to have electricity in their homes at all times, the production units must be able to meet these peaks. But there is also another solution: to try to reduce the peaks and create a smoother load curve.

This can be achieved by downsizing loads when the system indicates that there is a lot of consumption and insufficient production. This is usually a more economical way to manage a capacity shortage. In the first phase of the local energy systems project, no load management is included. Instead, these scenarios will be handled by the battery. When power consumption is peaking, the central grid will also assist.