Effect of Grid Disturbance on Plant Dynamics of a Nuclear Power Plant

Power generation in a nuclear plant is dependent on the Nuclear steam supply system (thermal energy source), the turbine generator (energy conversion), the circulating water system (heat rejection) and condensate/feed water system (regenerative heat and recycle of working fluid) and the plant electric system supporting these. These power generation processes must be operated so as to maintain energy and mass balance under changing conditions of load and environment. Grid electrical disturbances cause significant deviations in grid supply voltage and frequency. The abnormal conditions that accompany the imposition of grid electrical disturbances on a nuclear plant can disrupt the dynamic state of process systems equilibrium. The impact of grid electrical disturbances are in two different ways viz. (i) process degradation and (ii) impact on electrical components. Analysis of both these aspects are required to be carried out to design efficient reactor system high plant availability. In this project, effect of change in grid frequency and supply voltage on performance of motors and generator of a nuclear power plant has been analysed. The study is performed basically based on steady state conservative equations. Transient effects are not considered. It has been found that the impact on the performance of motors and generators are benign. An investigation on the process dynamics shows that due to provision of variable frequency drive systems for the important motors and other control measures, there is negligible impact on the heat transfer process. There is need for more detailed studies to be performed on the turbine control system, variable frequency drives and transient response for complete understanding and improvement. Keywords—