The influence of reclosure of single-phase system fault on pumped-storage machine

In modern power system, reclosing operation of single phase fault is commonly employed in order to improve operating stability and reliability. However, the successive electrical transients caused by system faults and subsequent switching operations give rise to mechanical stresses nearby electric machines. These stresses may exceed the endurance limit of certain machine parts and bring about slight and severe fatigue damage which is cumulative over the life of machines. In this paper, the sophisticated simulation model, including an infinite grid, lines, breakers, transformers, synchronous machines and mechanical shaft systems etc., is established to identify an interaction between system and machines. A line to ground fault and the single-phase-reclosing processes (SPRP) are simulated for both generator and motor conditions of pumped storage machine (PSM). Electric-magnetic torque characteristics and stator current curves are given. The whole stresses of stator core and frame are calculated by FEM and fatigue loss is predicted. The results show that although there is some fatigue in parts, the impact of SPRP on PSM is acceptable. Thus, the structure of machines can be optimized, and an operating guidance will be achieved to SPRP of PSM.