Lessons learned from grid restoration and islanded operation tests with hydropower plants

Inhalt:
Sufficient preparation for a possible blackout scenario is fundamental for a secure power supply. Therefore real tests are essential in addition to calculation-based preparatory measures for grid restoration. This paper summarizes the effects and outcomes of two field test scenarios of grid restoration using hydropower plants. Further, the calculation results and the most important findings with a focus on load-frequency response are discussed. The two tests involve a grid restoration of a 110 kV grid with transmission lines of a total length in the range of 100 km ... 200 km. The tests took place in different locations in Austria and different load types were involved, such as large induction motors, synchronous motors, and converter loads. At the end of the analyses, an index is defined for different turbine types, describing the relationship between the rotational energy and the maximum frequency deviation for instantaneous load steps. The Turbine Type Performance Index (TTPI) enables the estimation of maximum frequency deviation in an island grid.