Modern automatic voltage regulators

Summary form only as given. This paper presents an overview of the currently employed AVRs, both the analogue and the digital, microprocessor based sampled data controlled devices with respect to their control algorithms. The main design aims and constraints are examined in terms of performance specification concerning the speed, accuracy and stability of control. The contradiction between transient and dynamic stability requirements and its present day resolution by introducing a power system stabilizing function into the AVR functions is explained. The aspects of using a supplementary PSS added to an AVR which is primarily tuned for voltage control against the merits of an integrated control algorithm are explored. The problems and practice of regulator tuning are described and examples of practically achieved performance are presented from test results. Finally the possible future trends in AVR design both in control algorithm and in hardware are explored with respect to intelligent adaptive control techniques and to multi-machine implementation of power system stabilization