The behavior of conventional and renewable generators as well as storage systems during short-term grid disturbances, or Fault Ride Through (FRT), is an important issue for grid-integration.
A distinction is made between different types of faults. On the one hand, there are undervoltage faults, or Under Voltage Ride Through (UVRT) events, which typically occur due to short circuit occurrences in the power grid. On the other hand, voltage rises, or Over Voltage Ride Through (OVRT) events, can occur, for example when large loads or generators are tripping. For this reason, the various international feed-in guidelines stipulate that grid-connected converter systems behave in a grid-stabilizing manner during such voltage faults and provide voltage-supporting reactive current.
Besides this, an imbalance of active power in the grid leads to grid frequency changes. In these cases, generators and storage facilities must adapt the active power fed to the grid in order to stabilize the grid frequency. The plants, which can adjust their output power during so-called Limited Frequency Sensitive Mode (LFSM) events, reduce their output power at over-frequency or increase it at under-frequency.
In order to be able to investigate and verify such behaviors, the Multi-Megawatt Lab has test facilities for test objects with powers of up to 10 MVA (FRT) or 1 MVA (LFSM).