The voltage and reactive power control service, provided on a mandatory or voluntary basis by the Voltage Service Providers (VSP), consists of making the reactive power (in absorption or production) of the technical units connected to the grid available to Elia. The activation of this reactive power is one of the means used by Elia to guarantee the stability of the voltage on the electricity transmission network.
Depending on their technical capacities, the technical units providing the voltage and reactive power control service are required to stabilize the voltage by absorbing or generating reactive power by automatic activation on the basis of the voltage level measured on the network and/or at Elia's express request (via manual activation). The terms and conditions of participation in the voltage and reactive power control service are described in the "contract for the voltage and reactive power control service" (or VSP contract) available on Elia's web site.