Shunt Reactors are used in high-voltage AC energy transmission systems to stabilize the system voltage during load variations. The electricity in a shunt reactor can be seen as a large coil which is connected between the line and the ground to absorb reactive power in the system. This function is especially important at high voltages - typically over 130 kV - and long transmission lines.
Cable systems require even more reactive power compensation, even at lower system voltage, due to the cable`s high capacitance. In addition to stabilizing the system voltage, the shunt reactor increases the useful (active) power, transmitted in the system.
The rating of a Variable Shunt Reactor (VSR) can be changed in steps. The maximum regulation range is typically a factor of two, e.g. from 100-200 Mvar. The regulation speed is normally in the order of seconds per step and around a minute from maximum to minimum rating. VSRs today are available for voltages up to 550 kV, and the largest VSRs in operation have a rating of 120-200 Mvar at 420 kV. This variability provides several benefits compared to a traditional fixed shunt reactor. The VSR continuously compensates reactive power as the load varies, thereby securing voltage stability. Other important benefits:
− Reduced voltage jumps as a result of switching in and out of traditional fixed reactors
− Flexibility for future, unknown loads and generation patterns
− Improved interaction with other transmission equipment and/or systems such as coarse tuning of SVC equipment
− Reducing the substation footprint, if parallel fixed shunt reactors can be replaced with one VSR
− A VSR can be used as a flexible spare unit and moved to other locations in the power grid if needed.
Large and medium power transformers
If you want to purchase a product, need any pricing information or need help or support from ABB, please contact your local partner.