Optimal design of reactive power PI regulator for hydro power plants

This paper presents an optimal PI controller for automatic reactive power regulators (AQR) which equip some French hydro power plants. The developed AQR algorithm participates to secondary voltage control following some control performance criteria required by the Transmission System Operator. Controller parameters are calculated by solving a constrained nonlinear optimization that maximizes the robustness of the feedback control while incorporating the control performance specifications. That involves a dasiaworst casepsila design approach which takes into account modeling uncertainties and gain variations in the operating domain. Moreover a mere anti-windup strategy has been achieved in the AQR algorithm. Referring to Matlab simulations and measurements carried out on a 110 MVA pilot hydro unit, results are complying with demands.