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AC Electric Railway System
This model simulates an AC electric railway system, which is mainly composed of Scott-transformers, autotransformers, running rails, protection wires, feeders, messenger wires, and contact wires. The AC electric railway system is based on single phase 55/27.5 kV. AC feeding circuits supply electric trains with the electric power through three-phase to two-phase Scott transformers, feeders, contact wires and rails. Autotransformers are installed approximately at every 10 km with circuit breakers which connect adjacent up and down tracks at the parallel post.
The system models containing different feeders and the contact wires models, namely the distributed parameter line (DPL) model, 1-section PI line model, and multi-section PI line model, were built up for the system transient studies. For the DPL model, the short length of the lines sets a limitation on the maximum time step, i.e. 33.3us corresponding to the propagation delay of a 10km line. The PI line model has no such limitation. However, on one hand, the simulation accuracy of high-frequency transients decreases as the model time step increases. On the other hand, the calculation time for the PI line model is larger than that of the DPL model and increases as the number of PI section increases.
This model represents a typical AC electric system with short length lines or cables. It shows the excellent capacity of eMEGAsim to simulate this kind of system with DPL model or PI line model in real-time. In real-time simulation of the system, four models, namely 4-CPU DPL model, 2-CPU DPL model, 2-CPU 1-section PI model, and 2-CPU 2-section PI model, achieved the minimum step size of 9us, 29us, 34us, 58us respectively on a dual quad-core machine running at 2.3 GHz.
With eMEGAsim, it is possible to study the system steady state and transient during fault conditions. eMEGAsim and the models would be a powerful tool for the design and planning of AC electric railway system and other AC electric systems with short length line/cables.
For a good overview, click Here (3 MB)
|CPU Type||Dual Intel® Core™ 2 Quad Processors with a clock speed of 2.3 GHz and 2 GB RAM|
|Number of CPUs||6|
|Minimum Time Step|