Power flow & voltage stability analyses and remedies for a 340 MW nuclear power plant using ETAP

Power flow & voltage stability analyses of a power system are essential for both design and operating stage performance monitoring and to ensure stable and reliable grid operations. In this work, electrical model of a 340 MWe Nuclear Power Plant (NPP) is developed on Electrical Transient Analyzer Program (ETAP), and power flow & voltage stability analyses are performed. Effects of under-& over-voltage transients due to instability in outer power grid on NPP electrical system are then studied. Using power flow analysis that exploits Newton-Raphson algorithm, buses operating at under-voltages, due to power grid transient, are identified and their voltages are improved using on-load tap changer of transformer and reactive power compensation. Capacitor banks and their optimal positions are suggested by using optimal capacitor placement module. Similarly, in case of over-voltage transient, the way the voltages of NPP electrical system are disturbed and methods to overcome them are also implemented. As the nuclear reactor startup is time consuming and expensive, so the results are beneficial since they eliminate the chances of undesired NPP reactor trip due to “reactor coolant pumps buses low voltage” signal. Promising results have been accomplished regarding voltage stability of the NPP.