Search Results (6)

In the context of smart cities, direct current overhead contact lines, usually adopted to power urban transportation systems such as trolleybuses, tramways, metros, and railways, can serve as a backbone to connect different modern emerging technologies. Among these, in-motion charging (IMC) trolleybuses with on-board batteries are expected to be very impactful on the DC network’s power flow and may require specific voltage and current control. These factors motivate the development of a simulation tool able to emulate these devices’ absorption and their effect on the supply infrastructure. The main innovative value of the work is to improve a simulation model of a trolleybus grid through a data-driven approach by using measurements of voltage and current output from a traction substation. The measurements are essential for understanding the behavior of vehicle weight variation throughout the day. Thanks to this information, a characterization of the current draw by conventional trolleybuses and IMC trolleybuses is then provided for each trolleybus route in a specific power section of the Bologna trolleybus system. By integrating the variation in vehicle weight within the model, a simulation of a possible daily operation of a trolleybus feeding section has been performed, obtaining a 7% error between the daily energy calculated from the simulation and that obtained through measurements. This analysis demonstrates the feasibility of the adopted simulation tool, which can also be used to evaluate additional hypothetical trolleybus operation scenarios. One of these possible scenarios considers IMC vehicles, and it is also evaluated in this paper. Full article

This paper analyzes the results of a trial operation of a battery-based buffer station supporting a selected section of trolleybus power supply systems in Pilsen, Czech Republic. The buffer station aims to prevent the catenary from excessive voltage drops in a part of the route that is most remote from the traction substation. Compensation of voltage drops is carried out by continuously measuring the catenary voltage and injecting the current into the catenary if the voltage decreases below a preset value. The effectiveness of such a solution was evaluated by the analysis of numerous experimental recordings, both from the buffer station itself and from trolleybuses in operation. Further on, based on the recordings, a utilized battery capacity was estimated and a control method for decreasing the required capacity was proposed. The optimal capacity analysis, supplemented with an evaluation of required output current rating, was used to define the best storage technology for the considered application. Full article

The development of electromobility involves the development of electric cars charging infrastructure. The increase of the number of chargers poses new demands for the AC power grid, especially in regard to its capacity of delivering high peak power. As an alternative for the public AC power grid, urban electrified transportation systems (trams, trolleybuses, and metro) can be used for supplying electric cars chargers. The article discusses four options of integrating electric cars chargers with a traction power supply system. The option of connecting the charger to the traction overhead supply line has been selected due to the spatial availability of the power source and possibility to use regenerative braking energy for charging. A set of criteria has been developed for analysing the capability of the traction supply system to feed electric cars chargers. An exemplary feasibility analysis was carried out for trolleybus traction supply system in Gdynia, Poland. The impact of installing the charging station on specific traction supply parameters has been predicted using present-state recordings of electrical parameters and assumed charging station power. The study shows that every supply section of the considered trolleybus traction system has the capability of installing a fast-charging station, which provides opportunities of expanding the charging stations network in Gdynia. Full article

The paper proposes a novel approach to modeling electrified transportation systems. The proposed solution reflects the mechanical dynamics of vehicles as well as the distribution and losses of electric supply. Moreover, energy conversion losses between the mechanical and electrical subsystems and their bilateral influences are included. Such a complete model makes it possible to replicate, e.g., the impact of voltage drops on vehicle acceleration or the necessity of partial disposal of regenerative braking energy due to temporary lack of power transmission capability. The modeling methodology uses a flexible twin data-bus structure, which poses no limitation on the number of vehicles and enables modeling complex traction power supply structures. The proposed solution is suitable for various electrified transportation systems including suburban and urban systems. The modeling methodology is applicable i.a. to Matlab/Simulink, which makes it broadly available and customizable, and provides short computation time. The applicability and accuracy of the method were verified by comparing simulation and measurement results on an exemplary trolleybus system operating in Pilsen, Czech Republic. Simulation of daily operation of an area including four supply sections and maximal simultaneous number of nine vehicles showed a good conformance with the measured data, with the difference in the total consumed energy not exceeding 5%. Full article

When a trolleybus travels through insulated sections of the overhead contact line, it experiences momentary power interruptions, which adversely affect the vehicle’s on-board auxiliary subassemblies. To reduce these negative effects, one can harness energy recovered via regenerative braking. A model power supply circuit diagram for structural systems of the trolleybus is proposed. Simulation tests were carried out to develop a method for analyzing power supply to trolleybus auxiliary devices and verify it in a real-life example. The results allow determination of the limit power that can be generated by the trolleybus drive system to feed auxiliary devices during interruptions in power supply from the overhead contact line. The possibility of powering the on-board auxiliary equipment of a trolleybus using energy from recuperation with a traction motor is presented. Full article

The paper presents a novel approach toward the use of solar energy systems in public transportation. The concept of energy generation in PV systems for supplying a trolleybus transportation system is proposed for the city of Gdynia (Poland). The suggested way of energy production allows reducing the environmental harm impact of the municipal transportation system. Moreover, the proposed way of green energy use can be a more profitable alternative for selling transport items (trolleybuses) to the public energy grid. The presented analysis is based on the Monte Carlo Model method of stochastic simulation. It allows taking in consideration the random nature of the vehicle movement caused by road congestion and the uncertainty of the solar radiation. Several localisations of the PV system and the different structures of traction supply systems were analysed. The results of the analyses showed that despite of the uneven load in the traction power supply, it is possible to use 80% of the generated solar system energy. Full article