Variable shunt reactor

Variable shunt reactors are used in high voltage energy transmission systems to stabilize the voltage during load variations. A traditional shunt reactor has a fixed rating and is either connected to the power line all the time or switched in and out depending on the load. Recently [1] variable shunt reactors (VSRs) have been developed and introduced on the market. The rating of a VSR can be changed in steps: the maximum regulation range depends on the capability of the on-load tap changer used in combination with the regulation winding used for the shunt reactor. The maximum regulation range has increased over the years,[1] from 50%, up to 80% at some voltage levels.[2] VSRs are considered[1] technically advanced products and are mainly supplied by larger global manufacturers.

Advantages

The variability brings several benefits compared to a traditional fixed shunt reactors. The VSR can continuously compensate reactive power as the load varies and thereby stabilise the voltage. Other important benefits are:

  • reduced voltage jumps resulting from switching in and out a traditional fixed shunt reactor
  • flexibility for future variation in load and generation patterns
  • improved interaction with other transmission equipment and systems such as coarse tuning of SVC equipment
  • limiting the footprint of a substation: if parallel, fixed shunt reactors can be replaced with one VSR
  • a VSR can be used as a flexible spare unit and be moved to other locations in the power grid if needed
  • mitigation of zero-miss phenomenon, while energisation of long power lines and cables[3]

References

  1. ^ a b c "Technology and utilisation of oil-immersed shunt reactors". 2016.
  2. ^ "(Variable) Shunt Reactor". www.entsoe.eu. Archived from the original on 2023-10-01. Retrieved 2024-01-13.
  3. ^ "Hitachi Energy Publisher".