SIMUX– INTEGRATED RAILWAY SYSTEM SIMULATION SOFTWARE
SimuX software has been developed at Istanbul Technical University. It is under continuous development with new features as per new needs and developments emerge in the sector.
SimuX is used to simulate traction system, signaling, operation and energy efficiency together with all components of a rail transportation system. The software has been used successfully in many projects to assess new operational conditions/rules/vehicles in an existing system as well as designing and/or verification of traction power supply systems of new lines, and it has been confirmed that its results are highly accurate.
SimuX can be used to determine:
- Train performance under operating conditions,
- Dimensioning of traction power system,
- The adequacy of traction system and its components,
- The maximum, minimum and average voltage values in a pantograph of a train,
- The rail potential and stray current,
- Energy consumption and losses,
- Energy saving strategies,
- The effect of regenerative braking and calculation of the ‘receptivity and recuperation ratios’ of the line.
- The effect of different feeding schemes,
- Short circuit current.
In simulation of transportation systems, there are hundreds of parameters to be entered into the model by the user in order to have a satisfactory simulation. Main inputs include followings;
- Names, Lengths and Numbers of Lines and the passenger stations on these lines with minimum and maximum dwell times
- Curves, Gradients, Speed Limits and the maximum operational speed
- Data related to depots which are connected with the lines
- Operation rules on the line (number of cars in the trains, headways, departure and arrival points, skip-stopping station names)
- Number of traction power substations, their locations and naming, equipment data of the substations, isolating sections between substations, catenary / 3. rail system data and rail potential control device
- Data on train characteristic (vehicle maximum speed, vehicle empty / full weight, maximum acceleration, braking and jerk values, traction force – speed diagram, braking force – speed diagram, etc.)
Unlike most competing products, SimuX’s dynamic simulation algorithms model the interaction – during each simulation time step – of trains and the power system as conditions change along the alignment. Voltage variation at the train affects train performance, so when the voltage decreases, the acceleration, velocity and location of the train are altered. By this method, traction power drawn by the train decreases, enabling the traction power system to partially recover from the voltage sag. SimuX takes this performance loss into account by incorporating this non-linear control function into its model for both motoring and regenerative braking modes.
As specified in the EN50388 standard, useful average voltage value which should be complied in mainline railway systems can be calculated with the help of SimuX. Combined with this current/power limitation under lower voltage behavior modelling and its ability to model VLD (voltage limiting devices attached to the return circuit-running rail), SimuX enables us to find achievable headway time under the worst case scenarios such as failing two neighboring substations.
SimuX can analyze the impacts of a train bunching on the traction power system and the ability of the traction power supply system to support multiple “stacked” trains restarting.
By capability of incorporating numerous different train types and compositions in the same simulation model, SimuX supports the development and optimization of integrated operating plans.
Its advanced interface and allowing the use of different numbers of passenger loading for each station enables more realistic dimensioning of systems.
The use of on-board energy storage systems (ESS) and the inclusion of catenary-free zones in the simulation can provide dimensioning of the onboard ESSs and optimizing the charging times required in the designated areas.
According to the needs of the project, SimuX can use 100 milliseconds or less iteration time and allows the full compliance of the some critical values compared to the standards such as rail voltage.
The use of a single contact wire in visually sensitive areas, e.g. historic and touristic places, necessitates the use of reinforced cables embedded in the ground in many tram projects. SimuX can model these feeder cables and their connection points to the contact wire separately to optimize the frequency of the connection points to the contact wire. Likewise, in some cases, cables parallel to the running rail can be modeled so as to reduce the rail voltage.
With these and similar dynamic simulation options, SimuX prevents over-sizing of systems and ensures the accuracy of the decisions of simulation-based investments.
