Analogue AVR model for use in real time transient simulation of small salient pole alternators

The paper describes a real-time transient model for the common analogue automatic voltage regulator (AVR) used in small salient pole alternators (up to 5 MVA) and the constituent algorithm, which has been developed to initiate and allow simulation. The model has been validated by comparison of prediction and measurement of open loop response to numerous step inputs. Data have been recorded for a long period of time and there is consistently good agreement between simulation and measurement. Typical responses to a step input are presented in the paper. These include all control signals and the pulse width modulated (PWM) output of the AVR for a few cycles of the open loop transient. The model is also examined in an overall closed-loop system simulation that includes the main alternator and load, the exciter machine and the three-phase diode rectifier. Results are illustrated and these confirm the efficiency of the model in its ultimate mode of operation.