Out-of-step protection of generator using analysis of angular velocity and acceleration data measured from magnetic flux

Abstract This paper presents a new flux-based method for out-of-step protection of synchronous generator. The available measured angular velocity and acceleration data from magnetic flux of the generator, at the location of the relay, are used to detect out-of-step conditions. An out-of-step condition can be distinguished in the point in which the polarity of the angular acceleration changes from a negative to positive value and the angular velocity is greater than the base angular velocity. The basic idea of the approach stems from the fact that the resultant magnetic flux rotates at synchronous speed and cannot change rapidly. In other words, this constant magnetic flux will not be affected by switching transients due to highly inductive characteristics of the machine. Finally, the simulation results verify the straightforward application of the proposed technique even for a multi-machine power system. Therefore, the proposed approach can be directly applied to an interconnected power system without any need to cumbersome network reduction methods. Furthermore, the proposed technique does not require any offline studies and overcomes some of the problems associated with the previous solutions.