Effect of Increased Generation and AVR on the Transient Stability at a Nuclear Power Plant

Abstract Automatic Voltage Regulators (AVR) installed on generators play a major role in transient stability analysis. Using DIgSILENT software permits analysis of the behavior of the system under transient condition with and without the AVR. Analysis of the critical clearing time using results from the simulation will give insight into the effect of the AVR on the critical clearing time. This will allow for more defined protection settings to prevent unnecessary trips. In this paper, DIgSILENT is used to determine the critical clearing time at Koeberg nuclear plant taking into account the AVR. Various scenarios such as increase in generation, AVR switched in and out of circuit and three-phase short circuits on the HV busbar were simulated, assessed and analyzed to validate the model and give insight into the critical parameters that can be modified to protect Koeberg generators from pole slipping. The case studies show that the generators will not pole slip with an increase in generation and that the AVR has little to no effect on the critical clearing times when the HV network is subjected to a three-phase fault.