An adaptive power-voltage hierarchical control based on improved consensus algorithm for DC traction power supply system

Abstract

Droop control is a typical method for achieving power-voltage control in DC systems. However, the movement of traction trains causes real-time changes in the resistance of the traction network, leading to variations in power sharing at traction substations (TSSs) determined by droop control, thereby impacting the voltage operation quality of the DC traction power supply system (TPSS). In this paper, an adaptive power-voltage hierarchical control strategy considering rational traction power sharing and voltage compensation based on the consensus algorithm is proposed to mitigate the impact of train movement. Firstly, to enhance the convergence speed of inter-station communication algorithms in the system layer control, an improved consensus algorithm with a convergence factor is proposed to calculate the average values of TSS state variables needed for the local layer control. Secondly, in the local layer control, the per-unit average power of TSSs is introduced to compensate for the impact of train movement on the droop coefficient. Furthermore, to reduce power loss in the traction network, a base quantity for virtual power is proposed for further compensation of the droop coefficient. Through dynamic compensation of the droop coefficient, a rational sharing of traction power according to rated capacity and power supply distance at TSSs is achieved. Moreover, the voltage average is utilized for secondary compensation of voltage deviations at TSSs. Finally, simulations based on a four-terminal DC TPSS have been established to validate the effectiveness of the proposed method in terms of power sharing and voltage control.