Identifying Potential Interaction between BWR Plant Dynamics and Power System Electromechanical Oscillations

The need for maintaining oscillatory stability has long been recognised in power system analysis. The possibility of unstable power oscillations in boiling water nuclear reactors (BWR) has also been known and managed since early in the history of this design concept. In this paper, an analysis of measurements from the Nordic power system is presented that suggests that in certain circumstances, power system electromechanical oscillations and BWR power oscillations could interact. Specifically, it appears that reduced power output from a reactor, combined with low system loading increases the likelihood of the interaction. The significance of this phenomenon is that the probability of occurrence of unstable oscillations when these circumstances coincide may be greater than previously thought. Heuristic rules, measurement technology and stabilisation techniques could all be used to improve the security of the system and reduce the incidence of unstable reactor power oscillations