This work presents a comprehensive set of steady state models to be included in power flow simulation studies of DC railway networks. This simulation framework covers all important aspects and features of each element of modern DC railways. The proposed models are simplified to achieve the maximum simulation speed while keeping the required accuracy. Not only non-reversible, controlled and uncontrolled reversible substations are considered, but also on-board and off-board accumulation systems. The train model can consider the low network receptivity (overvoltage protection for trains equipped with regenerative braking) and overcurrent protection. It is also possible to include in the simulation DC/DC links between nodes of the railway network at the same or different voltage. To date, there is no other work able to conjugate all the mentioned models in a complex multi-train scenario.

In this paper, a new procedure based on a backward/forward sweep (BFS) algorithm for solving power flows in weakly meshed dc traction networks is presented. The proposed technique is able to consider the trains as nonlinear and nonsmooth (nondifferentiable) voltage-dependent loads or generators. This feature permits the inclusion of the trains' overcurrent protection and the squeeze control. With the use of the mentioned controls, the conventional power flow problem becomes a voltage constrained power flow problem, and the interaction between the trains and the network can be accurately modeled. However, the train control induces a highly nonsmooth voltage-dependent load characteristic, causing convergence problems in most of the derivative-based algorithms. The proposed algorithm is faster, more robust, and more stable than the derivative-based ones. In addition, the authors present all of the formulation in a compact matrix-based form by means of the graph theory application and the node incidence matrix.

In this work, a simplified model of a 2x25kV bi-level traction power system for feeding high-speed trains is presented. A Modified Nodal Analysis (MNA) based algorithm for solving the system with and adaptive damping factor is also explained. The main novelties of this work are the inclusion of train protections (over-current) and (over-voltage) in the model and the development of the MNA solving procedure that increase the stability and robustness of the iterative solving process. Another important feature of the model is that it can be easily adapted to a single voltage feeding systems by deactivation of specific parameters. The accuracy and performance of the proposed simulator is compared and verified relative to the derivative based solvers.

In this paper, a decoupled model of a train including an on-board hybrid accumulation system is presented to be used in DC traction networks. The train and the accumulation system behavior are modeled separately, and the results are then combined in order to study the effect of the whole system on the traction electrical network. The model is designed specifically to be used with power flow solvers for planning purposes. The validation has been carried out comparing the results with other methods previously developed and also with experimental measurements. A detailed description of the power flow solver is beyond the scope of this work, but it must be remarked that the model must by used with a solver able to cope with the non-linear and non-smooth characteristics of the model. In this specific case, a modified current injection-based power flow solver has been used. The solver is able to incorporate also non-reversible substations, which are the most common devices used currently for feeding DC systems. The effect of the on-board accumulation systems on the network efficiency will be analyzed using different real scenarios.

The work presented in this paper describes a multi-issue negotiation protocol between active consumers and a management platform in order to establish load coordination in a highly congested network. The multi-issue negotiation protocol considers simultaneously the consumption interval, the price, and the size of the energy packages, which is the main contribution of this work . Regarding the implementation methodology, the proposed algorithms have been implemented using MATLAB classes that allow emulating the behaviour of a multi-agent system in which each vehicle is an agent that interacts with the platform, which is another agent. In the present work, and without loss of generality, the algorithm is applied to coordinate the charging of electric vehicles (EVs) in a distribution network in which building loads represent critical loads. The algorithm is tested in a realistic environment, and its stability and performance are evaluated. Furthermore, the description of the algorithm is provided in a generic form, and it could be applied to any other scenario.

This paper analyzes different forms of carrier (high frequency) excitation for sensorless control of three-pole active magnetic bearings. Three options are compared: rotating injection, pulsating injection at a fixed angular position, and pulsating injection at an angular position synchronous to the minimum reluctance axis. Criteria for comparison include sensitivity to displacement changes, parameter and operating point dependence and signal processing burden for signal isolation. Theoretical derivations, simulation results and experimental results are included. The system model and the practical implementation will be shown to share similarities with high frequency injection sensorless methods for AC machines but also to have significant differences mainly on how pulsating carrier signals are used.