Hydropower flexibility for large-scale integration of renewable energy sources

Hydropower is one of the most flexible sources of electricity production. Power systems with considerable amounts of flexible hydropower potentially offer easier integration of variable renewable generation. However, there exist operational constraints to ensure long-term security of supply while keeping river flows and reservoirs levels within permitted limits. Due to the inherent uncertainty of the weather dependent hydrological cycle, regulation constraints on the hydro system, and uncertainty of internal load as well as variable generation (wind and solar), the flexibility assessment of hydro system is complex. In order to properly assess the adequate available hydropower flexibility, it requires proper modelling of all the underlying interactions between hydropower, the thermal generators and the power system with a large share of variable renewables. The existing experience of wind integration in hydro-dominated power systems reveals the need for simulation methodologies in order to capture hydropower flexibility.