Solution of DC Railway Traction Power Flow Systems Including Limited Network Receptivity

Abstract

The voltage solution of DC railway traction power networks is classically obtained via the current injection (CI) method, which is based on solving a sequence of nodal voltage equations. Specialized techniques, which build on the CI method, have been proposed for simulating limited network receptivity due to voltage rise constraints and nonreversible substations. These techniques may require a multitude of power reduction steps for modeling the local controller operation of trains in regenerative braking mode, and they consequently lead to a large computational effort. This paper proposes a sensitivity-based approach for computing the regenerative train power that can be returned to the network without causing over voltage. In the case of nonreceptive substations, each regenerating train is switched to a voltage-current source model and the CI method is used to further adjust the power that can be received by the network; a two-phase approach is used to compute the regenerative train resistance without recourse to iterations. The proposed method is tested on network models with branched lines, detailed return circuits, and having up to 144 trains. The computational performance comparisons show that the proposed method for simulating local controllers can be significantly faster than the classical power reduction method.