10 research outputs found
Traction Power Substation Load Analysis with Various Train Operating Styles and Substation Fault Modes
Simulation of railway systems plays a key role in designing the traction power supply 13 network, managing the train operation and making changes of timetables. Various simulation 14 technologies have been developed to study the railway traction power network and train operation 15 independently. However, the inter-action among load performance, train operation and fault 16 conditions have been fully understood. This paper proposes a mathematical modeling method to 17 simulate the railway traction power network with consideration of multi-train operation, driving 18 controls, under-voltage traction, and substation fault modes. The network voltage, power load 19 demands, energy consumption according to the existing operation are studied. The hotspots of the 20 power supply network are identified based on the evaluation of train operation and power demand. 21 The impact of traction power substation (TPSS) outage and short circuit on the power supply 22 network have been simulated and analyzed. The simulation results have been analyzed and 23 compared with the normal operation. A case study based on a practical metro line in Singapore 24 Metro is developed to illustrate the power network evaluation performance
Fast Quasi-Optimal Power Flow of Flexible DC Traction Power Systems
This paper proposes a quasi-optimal power flow (OPF) algorithm for flexible
DC traction power systems (TPSs). Near-optimal solutions can be solved with
high computational efficiency by the proposed quasi-OPF. Unlike conventional
OPF utilizing mathematical optimization algorithms, the proposed quasi-OPF
adopts analytical mapping from load information to near-optimal solutions,
hence considerably accelerating the computation. First, we study the mechanism
and physical meaning interpretation of conventional OPF based on a new modeling
method and successfully interpret the mechanism of conventional OPF in flexible
DC TPSs. Then, the analytical mapping from load information to near-optimal
solutions is obtained inspired by the mechanism of conventional OPF, and the
quasi-OPF algorithm is designed based on the mapping. Since the mapping is
based on simple arithmetic, the quasi-OPF algorithm can solve OPF with much
less execution time, achieving subsecond level calculation and a speed-up of 57
times compared to conventional OPF. The effectiveness is verified by
mathematical proofs and a case study with Beijing Metro Line 13. It provides an
insight into the mechanism and physical meaning of OPF, and is a powerful tool
for flexible DC TPSs to analyze the effects of coordinated control, design
real-time control strategies, and solve operational problems in planning
Regenerative Braking Energy Utilization Analysis in AC/DC Railway Power Supply System with Energy Feedback Systems
In the power supply system with energy feedback system (EFS)s, the energy from EFS (WF) will flow to rectifiers, which is circulation flow (CF). However, the efficiency of CF between substations has been rarely studied. Besides, the relationship between the train operation and regenerative braking energy (RBE) utilizing efficiency is not clear. In this paper, the energy flow structure of the AC/DC railway power supply system including CF is established. In the double-train system, promoting CF when the trains’ distance is long can be beneficial to power utilization efficiency. Chengdu Metro Line 9 is analyzed as the multi-train system based on the iterative AC/DC power flow algorithm. The key to energy saving includes reducing the energy consumption of on-board resistance and the DC traction network loss. Compared with the catenary and rail system, the fourth-rail system can promote system energy efficiency by 23.5% at most. The CF and energy fed to main substations counts for less than 2% and 8% of WF. When the headway time is short, RBE should be avoided feedback to EFS, while the feedback power of EFS should be advocated when the headway time is long. The results can help guide the operation of urban rail to save energy