News articles 02.05.2025
Pilot project in Halmstad: Aidon Feeder line solution for visualising the load on distribution transformer stations
Since March 2025, Halmstad Energi och Miljö has access to a completely new type of data from their low voltage network. By equipping two of their distribution transformer stations with Aidon FMD devices, they are now measuring the power flow for each feeder line going out from the stations.
The innovative Aidon FMD device is in practice a set of simplified electricity meters packed to a smaller size, equipped with current transformers for each phase and feeder line. These meters are connected to a full-blown CT meter which measures the whole transformer station. The station meter also operates as a communication gateway, transmitting the data from the FMDs to Aidon head-end system.
Installation of the FMD devices was an uncomplicated effort which required mounting onto a DIN rail in the transformer station. When connected to the CT meter gateway, the blinking LEDs on the devices confirmed when the data pipeline was ready to start delivering the measured values.
What is the purpose of this solution?
- The idea is to monitor in detail the load profile of each feeder and verify that the load is within the specifications, and to check if there is free capacity for future customer connections.
- One typical use case is to monitor the increasing amount of micro-production. If electricity production in any feeder increases uncontrollably, it can have impact on the end customer voltage levels. In addition, it could cause phase overload which can blow the fuses in worst case scenario.
- Another important task is monitoring how well the load is shared between the three phases on each feeder. For example, one phase might have become much more used than the two other ones, due to increase of electric car chargers or other end customer equipment. The risk is that one feeder gets overloaded or reaches its maximum capacity too soon. In this case, the DSO would solve the problem by re-organising phase connections at the customer.
The visual part of the solution is Aidon Explorer, a graphic tool for visualising the data collected from the FMD devices. Aidon Explorer provides different views over selectable periods such as:
- Transformer view to see the total energy flow in a station, including phase distribution and usage in percentage of each feeder fuse size.
- Feeder line view where you can choose between average load graphs, or detailed curves with currents per phase, imbalance calculations, Power Factor, and more
- Detailed voltage variation, including imbalance calculations
The areas of Halmstad Energi och Miljö that were chosen for the pilot have some specific characteristics.
- One area is a typical household area with many solar panels which they want to monitor more closely.
Here is an example from one of their feederliners where you see a clear alternance between consumption and production during the sunny hours. There is also very little imbalance, which is good. (Click to view a bigger picture.)
- One other area is known to have some imbalance in the network, such as potential overload or uneven phases that they wish to measure more in detail. A corrective action could be to help end customers change phase connections if needed.
Here is an example from another feeder line. It is a household area with recurring phase imbalance (Phase L1 has often much more consumption than L2, L3 and Phase L2 has often much more production than L1, L3 ) (Click to view a bigger image.)
– We see the Aidon Feeder Line solution as an interesting tool for collecting data and analysing the condition of our low-voltage network for each outgoing feeder line, and over time being able to monitor phenomena related to changes in our power grid. We are in the startup phase and will continue monitoring over the coming months, after which we will evaluate the benefits of the tool and possibly use the equipment in more trafo stations, says Emma Herrlin, Power Engineer at Halmstad Energi och Miljö Nät.
