STARS – Black start algorithms through resilient satellite communication

Restoring the electricity grid after a large-scale outage is a demanding process that requires the coordination of several distributed operating resources. Today, this coordination takes place via local telecontrol networks and via telephone-based coordination of remote grid segments. Depending on the black start strategy, one or more network segments are started up and synchronized, and subsystems that are not black start-capable are gradually added. The effectiveness of the black start strategy is a critical resilience factor and in most cases it significantly determines the time until power is restored. Depending on their duration, nationwide system failures can result in damage running into billions.

To ensure black start capability, it makes sense to rely on redundancy and thus on concepts for regional grid reconstruction. In Austria, the aim is currently to increase the number of subsystems with black start capability from two to seven. Bottom-up utilization of the increasing number of photovoltaic and wind energy plants is desirable, but it is currently not technically feasible or only feasible to a limited extent. The requirements regarding “grid forming” functionality for distributed generation are increasing, and in principle this also includes black start capability. However, the power and overload capacity of inverters is limited. Coordination between several devices is therefore required, as a single small-scale system is not able to restart a significant part of the grid.

In the future, new concepts for the bottom-up black start of electrical grids based on explicit communication between the involved systems could therefore be helpful. This would make it possible to include some of the systems that are not currently considered black-start capable in the formation of supplied islands that can be synchronized and interconnected step by step.

However, in the event of a prolonged large-scale power outage, the communication capabilities are not available, and the necessary coordination is no longer possible. Modern satellite communication based on low earth orbit (LEO) satellites can provide a remedy. The satellites are self-sufficient anyway and the overall system can be designed such that only the endpoints of communication (source/destination) require power.

Security of supply is the top priority in the design decisions for the electricity grid. A high volume of distributed volatile generation massively increases the demands on the electricity grid. There is a risk that the threat of a blackout (resilience) will block the energy transition.

The STARS project attempts to resolve this potential blockade by ensuring that the coordination of small-scale distributed generation is still possible even after longer power outages. To this end, a simulation model of the electricity grid and the telecommunication network is being developed. For the model of the communication system, knowledge is gained from commercially available LEO satellite systems. The coupled simulator will be used to develop and evaluate new communication-based black start procedures.

As a result, the exploratory study will produce quantified findings regarding the question whether black start coordination of small-scale renewable generation via satellite communication is a feasible and sensible approach.