Integrated control scheme for generators and VAr compensators in power systems

The authors describe the application of modern control theory to design a control scheme for a generator and a VAr compensator in a power system. The objective is to extend the operational margins of stability, whilst satisfying control requirements by introducing an integrated multi-variable controller to control both the generator exciter and the firing angle of the thyristor-controlled reactor of a TCR-FC compensator. The system dynamics are modelled in terms of measurable state variables and control inputs. This is achieved by using unbiased recursive least squares identification. On the basis of this identified model, the synthesis of an integrated optimal controller is achieved by minimizing a quadratic performance index using dynamic programming techniques. The effectiveness of the controller has been evaluated by computer simulation over a wide range of operating conditions and disturbances. System behaviour under transient conditions is assessed by examining the response to three-phase short circuits