Physical Modelling of a Light Rail HVAC System Using Long-Term Measurements

A method to develop a physical HVAC model of a light rail using only operation data from long-term measurements is presented. Physical HVAC modelling is often based on costly wind tunnel tests or time and computationally intensive CFD calculations. This method is a new approach using only data from everyday operation of the light rail, reducing modelling cost and improving the model accuracy since real life conditions are analysed. Data from two years of passenger operation of a suburban light rail in Karlsruhe, Germany, is used. A standard physical model for a HVAC system and a train compartment is developed. This model is parametrised using data driven modelling and model training. For data driven modelling, the conducted data is analysed and suitable models are derived. For example, the cooling system is modelled using a look-up table based approach developed with the data. For model training, the data is first separated into test and training data. The training data is then separated into different batches (heating up, winter-night, winter-day and summer), to parameterise different physical quantities of the model. Using a systematic grid search, parameters that fit the training data in an optimal manner are found. Finally, the overall model is validated using the test data. Over a large temperature range from -5 °C to 35 °C the model shows good consistency with the test data. The mean absolute percentage error over all test data is 13 %. Within the batches, the summer data was modelled best with an error of about 8 %. The described method allows a fast and reliable method to develop an accurate physical HVAC model

Multiphysics Simulation of a Battery Electric Train Operation

The changeover from diesel driven multiple units to battery electric multiple units is a challenge for operators due to the limited range of these trains. Therefore, in this paper a tool is developed and described that simulates the entire operation of a battery electric train. The tool contains a model of the track, the vehicle, the timetable and the environment. The model of the track is built on elevation profiles, radius information and speed limitation. The vehicle model is derived from an electric multiple unit suitable for local and commuter train operation. To do parametric studies or model different train units it is easily possible to change vehicle properties. Modeling the timetable and the environment allows the simulation of an entire operation day. The overall simulation model was validated and is consistent. Finally examples show the simulation possibilities and features of the tool

Design Methodology for the Electrification of Urban Bus Lines with Battery Electric Buses

Electrically powered buses reduce CO$_{2}$ and noise emissions in urban areas and thus promote the trend towards more livable cities. Upon this reason, more and more cities are introducing their first electrified lines as pilot projects. However, no standardized technology has yet emerged, which is why statements on interactions between vehicle, operation and infrastructure in public transport are proving to be difficult to make. In order to be able to make statistically significant statements in this respect, a simulation model was developed that depicts the three subsystems vehicle, operation and infrastructure. On the basis of measurement data from the PRIMOVE research project in Mannheim, in which an urban bus line is operated with two electrically powered buses, the simulation model was validated and a data basis was laid for further investigations. As a result, simulation studies with more than 700 simulated operating days could be carried out, the results of which represent the input for the following statistical analysis. Based on this analysis, the interactions described above will be demonstrated in the design of the main technical parameters, the battery lifespan and the energy demand of electrical bus lines. Through the findings of these simulations, an optimized version of the already electrified bus line in Mannheim will then be presented. Finally, a novel design methodology for electrification based on a multi-objective optimization is introduced. All parameters of the system are variable in order to apply the presented methodology to other projects and thus underline the general validity of the work