Study on low frequency voltage fluctuation considering different running-vehicle numbers in electrical railway

Low frequency voltage fluctuation (LFVF) have occurred frequently in electrical vehicle-grid traction system (VGTS) in China recently. The phenomenon can result in serious voltage distortions, system instabilities, even bring about electrical locomotive traction blockades. To address this issue, the LFVF stability analysis of VGTS is carried out in depth in this paper. First, the mathematical descriptions of VGTS are deduced based on the equivalent AT traction network model and the actual HXd2B locomotive load model. Second, applying with the electrical parameters of Xu-zhou VGTS in China, the system stability based on Nyquist stability criteria is studied. Also, test results using the built VGTS model are compared to the real data, acquired from northern substation of Xu-Zhou in China, to verify the validity of mathematical VGTS descriptions and stability analysis respectively. The comparison results show that the conclusions of system description and stability can be useful for determining LFVF problem in electrical VGTS.