Obligatory reactive power service (ORPS)

The obligatory reactive power service (ORPS) is the provision of varying reactive power output. At any given output generators may be requested to produce or absorb reactive power to help manage system voltages close to its point of connection. All generators covered by the requirements of the Grid Code are required to have the capability to provide reactive power.


The reactive power provider must:

  • be capable of supplying their rated power output (MW) at any point between the limits 0.85 power factor lagging and 0.95 power factor leading at the BMU terminals;
  • have the short circuit ratio of the BMU less than 0.5;
  • keep the reactive power output under steady state conditions fully available within the voltage range ±5% at 400kV, 275kV, 132kV and lower voltages; and
  • have a continuously acting automatic excitation control system to provide constant terminal voltage control of the BMU without instability over the entire operating range of the BMU.

Service dispatch

Instructions for reactive power are normally sent from us to the generator via an electronic dispatch logging (EDL) system.

Generators are generally instructed to reach a target MVAr level within two minutes. This target will sit within the reactive performance capability of the generator, outlined in their performance chart.