Redispatching in an interconnected electricity system with high renewables penetration

• The paper presents a two-step model to determine redispatch costs and quantities.
• A detailed case study of the Belgian electricity system is studied.
• Redispatching costs can increase drastically with increasing renewables generation.
• Loop flows have an important impact on redispatching.
• Relaxing the N-1 security constraint can reduce redispatching considerably.

Grid congestion management is gaining importance in certain parts of the European electricity grid. The deployment of renewable electricity sources at locations with a weak grid connection and far from the load centers can lead to overloading of transmission lines. Redispatching, i.e., rearranging scheduled generation and consumption, might be needed to obtain a feasible and safe operational state of the electricity system. This paper studies the impact of three parameters on the redispatching quantities and costs: (1) loop flows through the electricity system, (2) an increase in renewable generation in remote areas, and (3) a curative and preventive N-1 security criterion. Towards this aim, a dedicated generation scheduling model is developed, consisting of a day-ahead market and a redispatch phase. The Belgian power system is considered as case study. Three general conclusions can be drawn from this paper. First, it is important to consider loop flows when quantifying redispatching, especially in a highly interconnected electricity system as the European system. The case study shows that loop flows can more than double the need for redispatching. Second, transmission grid constraints might restrict the deployment of renewables in certain areas. Third, relaxing the N-1 security criterion in congested grid areas from preventive to curative can drastically reduce the redispatch costs.