DSO TSO Technopedia

As more distributed energy resources are connected to the distribution grid, the level of difficulty in managing this grid increases significantly. This problem is more prominent in low voltage grids where there is a lack of visibility and controllability when compared to higher voltage levels. Recently, it has become increasingly clear that controllability of the LV grid must always begin with a monitoring/sensing process of our MV/LV transformer stations.

Solution: voltage and current monitoring of every low voltage feeder of the secondary substation, allowing for increased observability: real-time information, alarms and events, as well as time series information for the low voltage feeders.

A central unit (RTU) measures voltage on the secondary of the MV/LV power transformer (busbar level) and manages communication with the sensors installed at every feeder. The communication between the RTU and the feeder sensors is either RS485 or Ethernet. Architecture according to Figure 1.

Not country specific.

No special difficulties/challenges with implementation.

Main Use Cases:

1. Identification and location of faults or potential faults
• Real time monitoring of each of the low voltage feeders
• Specific alarmistic for the low voltage grid management (e.g., blown-fuse, short circuit, overload)
2. Energy quality measurement, according to standards
• Real time monitoring of the energy quality parameters (such as voltage flickers, harmonics, amplitude, unbalances, fast variations), according to applicable standards
• Replacement for dedicated energy quality measurement devices
3. LV grid topology identification (by correlation of data retrieved from smart meters and LV feeders)
• Identification of feeder and phase for each smart meter
• Low voltage grid topology creation / validation
4. Identification of technical losses
• Identification of unbalanced low voltage feeders
• Collection of key data for improved profile analysis regarding technical loss estimation
• Energy balances with higher granularity (per feeder and phase)
5. Identification of commercial losses / fraud
• Identification of commercial losses / fraud, by correlation of smart meters and LV feeders' data.
6. Network planning support
• Use of more accurate and granular data to enhance LV network planning activities
7. LV switchboard hot points detection
• Detect potential hot points in the LV switchboard, to avoid/reduce severe incidents (and outages) related to fires

TRL 9

Expected Locations:

• 2025 - Hungary, North Transdanubian Regions: 2,000 units (as part of the Danube InGrid HU program)
• 2025 - Hungary, South Transdanubian Region: 800 units
• 2025 - Hungary, Budapest and Pest Region: 750 units

The smart metering devices are capable of managing the following main datas and events:

• Type A:
• Events:
• Power outage
• Overvoltage
• Voltage sag
• Wire breakage
• Threshold violation
• Voltage drop below critical level
• Measurement datas:
• Voltage values (3-phase, min/avg/max)
• Current values (3-phase, min/avg/max)
• Active and reactive power flow
• Voltage asymmetry (min/avg/max)
• Rapid voltage change (3-phase)
• THD measurement (3-phase, min/avg/max)
• Individual harmonic measurements (3-phase)
• Flicker measurement
• Type D:
• Events:
• identical to Type A
• Measurement Data:
• identical to Type A, but does not include current values or active/reactive power flow measurement.

The Danube InGrid smart transformer IT data platform is a modern data platform (Lakehouse) built on an event-driven IoT architecture. The solution operates using a highly advanced, industry-standard big data architecture that complies with corporate standards and is complemented by additional services, including a containerized application development platform and flexible integration options.

The data platform is designed based on the Azure Well-Architected Framework and is implemented following cloud-native and DevOps principles.

The IT System is prepared to implement the following key functions:

• Receiving information from the asset registry and geographic system (INIS)
• Providing source data for system operation management
• Processing data from metering devices
• Processing events from metering devices
• Generating alerts
• Storing measurement data and events
• Creating measurement indicators
• Data validation and transformation
• Monitoring:
• Metering devices
• Measurement data
• Data quality
• Infrastructure, logs
• Performance tracking
• Generating reports and summaries
• Advanced, Microsoft Power BI-based standard dashboard interface with mobile display capability.

Technical configuration:

• IT Data Platform
• A complex cloud-based data platform designed for visualizing, analyzing, and configuring metering devices, covering all events and data.
• Complex measurement device
• Network voltage quality analyzer
• Can be connected to the grid without disassembly or operational downtime
• Measurement range [VAC]: 65…450
• Measurement range [A]: 0…6000
• RMS averaging period for signed active and reactive power flow [min]: 1…1
• Optional device extensions:
• PQM-EM current meter expansion module
• PQM-CRB Rogowski Coil Set

Our goal is to facilitate and manage the integration of renewables using grid technologies. This is achieved through the deployment of smart devices, which also support grid flexibility and resilience enhancement.

Benefits of the Solution:

• Near real-time insights into the grid (1-minute measurement data instead of previous ad-hoc measurements)
• Support for operational management
• Improvement of supply quality indicators
• Faster fault localization
• Monitoring of grid elements for overload protection
• Support for long-term grid planning with more accurate, up-to-date, and detailed data
• roviding reference data for system operation and other systems as part of the digitalized grid

TRL 8

Since 2025 with further developed concept, e. g. use of SF6-free switchgears.

The so-called digiONS (in german: “digitale Ortsnetzstation”), deployed by E.ON SE in their distribution grids, represent a hybrid solution that combines the proven infrastructure of conventional secondary substations with advanced digital technologies. These enhanced substations are equipped with smart components that enable:

• Real-time measurement of electrical loads
• Remote switching and control capabilities
• Uninterruptible auxiliary power supply

This integration of digital functionality significantly improves the operational flexibility and transparency of the grid.

The digiONS units used by E.ON SE are fully preassembled and tested prior to delivery to construction sites. Each unit is housed within a robust enclosure, accessible via secure metal doors, ensuring durability and protection in field conditions.

Station Components:

The digiONS station integrates the following core components:

• Medium-Voltage (MV) Switchgear: Facilitates the connection to the MV grid and includes remotely controllable switches, as well as short-circuit and earth fault indicators.
• Low-Voltage (LV) Distribution Unit: Distributes power to the LV grid.
• Transformer: Performs voltage transformation between MV and LV levels.

All primary components are equipped with measurement systems that continuously monitor operational parameters. These systems are connected to a secondary technology cabinet, which aggregates and processes the data.

All components are standardized, so that it is easy to exchange components from different suppliers (interoperability of components).

Communication and Data Management:

Collected data is transmitted to the DSO's grid control center and central data management system via secure communication channels. Supported communication technologies include:

• Public mobile networks (e.g., LTE/5G)
• Broadband connections
• 450 MHz radio technology

This ensures seamless integration with downstream systems and applications, enabling real-time monitoring, analytics, and control.

Auxiliary Power Supply:

Each digiONS unit includes a battery-based auxiliary power supply. In the event of a grid voltage failure, the system remains operational, allowing continued data acquisition and transmission.

E.ON's DSOs have already deployed thousands of digiONS units across their distribution networks to enhance grid visibility and operational control. These digital secondary substations continuously measure and report electrical parameters, with all collected data securely stored in centralized databases.

This real-time data is visualized and made accessible to field technicians, significantly improving their ability to identify and resolve incidents quickly. Beyond operational support, the data is also leveraged in advanced analytics projects, such as state estimation of the low-voltage (LV) grid. These estimations help predict potential overloads and congestion, enabling proactive grid management.

Regulatory Relevance and Flexibility Management The data collected by digiONS is also critical for compliance with the German Energy Industry Act (§14a EnWG). This regulation allows DSOs to temporarily adapt the power consumption of flexible assets—such as heat pumps and electric vehicle (EV) chargers—during periods of grid congestion.

Using state estimation models, DSOs can detect congestion in near real time. Based on this insight, they can initiate targeted interventions by signaling controllable household resources to reduce their load, thereby supporting grid stability and security of supply. This capability is a cornerstone of E.ON's broader strategy to digitize its distribution networks and manage the increasing complexity introduced by renewable energy integration and electrification.

TRL 9

“Die neue Ortsnetzstation: Schnittstelle zur digitalen Energie,” Westenergie.de, 2025.

“E.ON SE: Introducing low voltage observability and congestion management - Eurelectric - Powering People,” Eurelectric - Powering People, Dec. 06, 2024.