New legal requirements and the changing operational environment present new challenges to transmission network operators. In addition, energy transmission in the existing networks must be safely optimised without the risk of outages. This requires implementation of sophisticated software for optimisation of all network management aspects. The network operator TenneT is a strategic pioneer in this area.
TenneT and PSI have jointly developed functions for optimized network management and monitoring which significantly increase security of supply. They are implemented in the PSI control system PSIcontrol which is the core of the new solution (NLS08):
The alarm management monitors the load and frequency stability of the entire UCTE (Union for the Coordination of Transmission of Electricity) network.
The joint network control by the four transmission network operators in Germany optimizes the generation of secondary control power. International expansions of the cooperation are currently being planned.
Forecast calculation determines network congestions ahead of time. The data used for the forecast includes load and injections throughout Europe, weather and load forecasts as well as planned transfer across the network borders, and planned outages in the own network. When new data becomes available, the forecast is automatically recalculated. This provides accurate estimation of the network state for the next 48 hours.
The Day-Ahead-Congestion-Forecast (DACF) and 2-Day-Ahead-Congestion-Forecast (D-2CF) refers to the next day or the day after next, respectively. The Intra-Day- Congestion-Forecast (IDCF) provides the forecast for the remainder of the current day. The forecast result of the transmission network (topology, loads and infections) is displayed on the DAFC monitor. The Network Transfer Capacity (NTC) calculation determines the maximum possible energy transfer increase between two adjacent regions in relationship to the current forecast while avoiding congestions.
If congestion occurs in spite of the implemented tools, NLS08 determines possible corrections for resolving the congestions in the simulation mode of PSIcontrol and submits those to the network manager. The submissions include predefined steps, OPF results, and topological operations as well as change of power plant injections in the own network area.
OPF uses voltage control for minimization of transmission losses. In PSIcontrol, each network group can be set up with its own specific parameters. The backup strategy implemented in NLS08 supports operation of voltage control without OPF, too. This increases the availability of functions under all circumstances.
The voltages in the network groups are visualized using KIVIAT diagrams. This provides the operator with an efficient monitoring tool for the voltage levels. Limit violations by network calculation functions generate alarms in the system.
PSIcontrol is the only control system on the market which offers hourly import of DACF data sets of external networks via dynamic online connection. In addition, each external network area can be dynamically reduced (network group reduction) in case of data transmission errors from the respective external network. This increases the stability of the network security calculation which depends on measured values. Otherwise, if data for a part of the external network is unavailable, the estimation and load flow calculation for the entire network no longer converges.
The dynamic network group reduction implemented in PSIcontrol provides the operator with network security calculation regardless of the operational circumstances. In addition, the function is used for locating errors.
In current operating environments, operational security becomes increasingly important. NLS08 implements the requirements of the Operational Security Policy 3 by dynamic generation of external networks from the DACF data sets without static data engineering methods. This reduces the operational risks for the customer. The DACF data sets are updated by online connections. If online updates are temporarily unavailable, the already available DACF data sets are used as fallback for operation without the latest updates.
TenneT TSO GmbH is located in Bayreuth, Germany with about 750 employees. TenneT operates, maintains and expands the 220 kV and 380 kV transmission network in large parts of Germany. This includes 10,700 km ultra high voltage lines for efficient long-distance transmission between the Danish border and the Alps.
With 140,000 km2, the service area covers 40 % of the Germany surface area. TenneT TSO GmbH is a subsidiary of the Dutch grid operator TenneT B.V.