EDF experience with co-ordinated AVR+PSS tuning

State feedback voltage controllers including both active power and rotor speed stabilizing loops have been successfully used for many years on the French power system: the “Four Loop Regulator” (FLR) is installed on most of the largest French power plants. It will be replaced in the coming years by a robust coordinated AVR+PSS, called the “Desensitized Four Loop Regulator” (DFLR), having a good performance in terms of transient and small signal stability. It is shown here that the DFLR fan be tuned with few design parameters, using a systematic procedure. The opportunity to transform the specific structure of this controller into standard IEEE AVR+PSS structures has been proved. A two step method is therefore proposed for tuning the parameters of a standard IEEE AVR+PSS: (i) design a DFLR; and (ii) make the above-mentioned conversion, which depends on the type of the excitation system. The AVR+PSS obtained in this manner are efficient for damping all kinds of electromechanical oscillations of a large scale power system (including inter-area oscillations). This approach should be combined with modal analysis techniques to determine the best location of the AVR+PSS to be installed or retuned. Its efficiency has been verified on several large scale systems and is illustrated here on a modified version of the New England system. The obtained AVR+PSSs have a good robustness against significant changes in the characteristics of the network