Power Flow Analysis and Current Optimization Control in Automatic Neutral Section Power Supplier With Partial Capacity

Addressing the power interruption and speed loss issues induced by the neutral section in electrified railways, numerous automatic neutral section power supplier (ANSPS) systems were proposed. Among these, an ANSPS serving as railway power conditioner on time-division basis stands out for its low converter capacity, high utilization, and multifunctionality. Nevertheless, the current scheme has two points to be improved: one is the unclear power flow caused by circuit coupling, and the other is the excessive difference of current amplitudes and transmission powers in input legs due to the existing current control method, resulting in unbalanced leg heating and aging. To solve these issues, this article analyzes the power calculation method, elaborates on the proportion and path of the transmission power. Then, based on the power flow analysis, a novel current optimization control method is proposed. This method enables equal current amplitudes and balanced power transmission in the input legs, which is more conducive to converter design. In addition, the maximum current and the required capacity of the input bridge legs will also be reduced theoretically. Finally, its effectiveness is validated by the simulation results through MATLAB/Simulink and experimental results of a scaled-down prototype.