Untersuchung der FRT-Fähigkeit eines Hydrogenerators unter besonderer Berücksichtigung des Back-Swing-Effekts

Stability investigations have long been an important topic in grid operations and help to ensure the safe operation of the grid. Stability verification methods are defined in the grid connection conditions [1–7] and include, among others, the verification of the Fault Ride Through (FRT) capability of power generation plants, i.e., the capability of the plants to remain connected to the grid during defined voltage dips without losing their stability. This verification is often carried out through simulation. For larger plants (around > 10 MW), this is always the case. For smaller plants, it is the usual procedure, especially when the plant is designed for a specific project, which, for example, is the norm for hydropower plants. In this paper, different methods for investigating the FRT capability are analyzed. Two different approaches for generating a voltage dip are reviewed, which significantly influence the FRT and, thus, also lead to different plant behavior. For the first approach, the voltage dip is caused by a controlled fault impedance at the grid connection point, for the second approach, a voltage dip is simulated by modifying the equivalent voltage source representing the grid. Finally, the article also identifies and analyzes the parameters of the equivalent circuit which have a significant influence on the FRT capability.