LVRT - Low voltage ride through
Stable and reliable grid connection for wind turbines and wind parks
Wind turbine control systems that comply with World Wide LVRT Demands
LVRT (Low Voltage Ride Through – also known as FRT - Fault Ride Through) has become a crucial feature of the wind turbine control system.
The LVRT-term is capturing the ability of a wind turbine (or in reality a wind park) to stay connected to the grid throughout a short mains voltage drop (a brownout) or a mains failure (a blackout).
When the voltage of the grid is dropping it is essential that a wind park stay online in order to prevent major blackouts. It is not only essential that the park stays online - it is equally essential that the park is working actively to compensate for the faulty grid condition.
In China major blackouts (as a result of entire wind parks tripping and getting offline as a result of a brownout) have been seen. This has increased the focus of the LVRT feature of the wind turbine control system.
It is a fact that many wind turbine control systems installed just a few years ago does not have the LVRT-feature - and cannot in an economical way be upgraded to an - for the grid operator - acceptable performance.
That is why DEIF Wind Power Technology in close cooperation with the power converter supplier is enjoying a drastically increased interest for our control systems - not only for new installed turbines, but also for upgrading existing installed capacity. Laboratory testing as early as 2010 brought the proof-of-concept which has later been full-scale implemented.
We are proud of having got several wind parks controlled by our control solutions full-scale field tested and approved as being in full LVRT-feature compliance by Chinese grid-operators.
Whether the LVRT capability of a wind farm is satisfying for meeting the requirements is defined in grid codes issued by the grid operator. The capability of meeting these demands is decisive for whether the wind turbine/the wind park is allowed to be connected to the grid.
Examples of LVRT demands to the wind park (and derived from that – to the individual wind turbines) are;
- for short system faults (lasting up to 140ms) the wind farm has to remain connected to the grid. For supergrid (HV-grids) voltage dips of longer durations the wind farm has to remain connected to the grid up to more than 3 minutes
- During grid faults or brownouts a wind farm has to supply maximum reactive current to the grid without exceeding the transient rating of the plant
- On super-grids during voltage dips lasting more than 140ms the active power output of a wind farm has to be retained at least in proportion to the retained balanced supergrid voltage
As mentioned above the LVRT-demands are individually specified by the grid operators and might therefore vary from operator to operator and from country to country. For wind turbines the LVRT testing is described in the standard IEC 61400-21.
The LVRT-feature of wind turbine controls from DEIF WPT in combination with our Park Power Management solutions (including our forecasting solution) is all a wind park owner need to be in perfect compliance with the demands of grid operators worldwide.
Pitch control, turbine control or retrofit?
DEIF Wind Power Technology develops and installs innovative green solutions for pitch control, turbine control and retrofit. Overall to secure and increase turbine performance. Choose DEIF's wind power solutions to reduce your Levelized Cost of Energy (LCoE) and increase your green electricity production.