Application - ABB RELION REX640 Technical Manual

1MRS759142 C
4.5.8.6
REX640
Technical Manual
GUID-C0074B66-1817-4B36-B972-79F1828B70A1 V1 EN
Figure 447: Typical example of operation of LVRTPTUV
Activation of the BLOCK input resets the timers and deactivates the function outputs.

Application

Distributed generation, mainly wind and solar farms, are rapidly increasing due to
liberalized markets (deregulation) and the global trend to use more renewable sources
of energy. These farms are directly connected to grids, and due to their large size may
influence the behavior of the grid. These farms are now required to comply with
stringent grid connection requirement, which was previously mandatory only for high
capacity power plants. These requirements include helping grid in maintaining system
stability, reactive power support, transient recovery and voltage-frequency
regulation. These requirements make it necessary for the wind and solar farms to
remain in operation in the event of network disturbances.
Many grid codes now demand that the distributed generation connected to HV grids
must withstand voltage dips to a certain percentage of nominal voltage (down to 0%
in some cases) and for a specific duration. Such requirements are known as Low-
Voltage Ride-Through (LVRT) or Fault-Ride-Through (FRT) and are described by a
voltage versus time characteristics.
Typical LVRT behavior of a distributed generation can be divided into three areas
according to the variation in voltage over time.
Section 4
Protection functions
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