IET Electrical Systems in Transportation最新文献

Most utilities across the world already have demand response (DR) programs in place to incentivise consumers to reduce or shift their electricity consumption from peak periods to off-peak hours usually in response to financial incentives. With the increasing electrification of vehicles, emerging technologies such as vehicle-to-grid (V2G) and vehicle-to-home (V2H) have the potential to offer a broad range of benefits and services to achieve more effective management of electricity demand. In this way, electric vehicles (EV) become distributed energy storage resources and can conceivably, in conjunction with other electricity storage solutions, contribute to DR and provide additional capacity to the grid when needed. Here, an effective DR approach for V2G and V2H energy management using Reinforcement Learning (RL) is proposed. Q-learning, an RL strategy based on a reward mechanism, is used to make optimal decisions to charge or delay the charging of the EV battery pack and/or dispatch the stored electricity back to the grid without compromising the driving needs. Simulations are presented to demonstrate how the proposed DR strategy can effectively manage the charging/discharging schedule of the EV battery and how V2H and V2G can contribute to smooth the household load profile, minimise electricity bills and maximise revenue.

The stray current produced by a direct current (DC) transit system leads to the corrosion of rails and metallic structures buried under and around the metro line. One practical approach to diminish current injection into buried structures is to implement stray current collectors underneath the rail. An analytical method is proposed herein using voltage distribution indices (VDIs) to calculate the voltage and current collection level of each collector located under the rail soil, and the solutions are validated by comparing with modelling results. The proposed method helps to achieve the voltage of different points under the ground and the current reaching the collectors using a circuit model, without facing the limitations of practical methods, as a supplementary study for experimental tests. Moreover, the effect of different arrangements of collectors under running rails is modelled. The analytical method is deployed considering two objectives, that is stray current collection by the conductors and a reduction in the installation cost of the conductors. Various arrangements of stray current collectors are compared and evaluated. Using integral and matrix equations, current density and potential at different points under the soil are calculated and the obtained results are compared with European (EN) standards.

Despite low energy and fuel consumption levels in the rail sector, further improvements are being pursued by manufacturers and operators. Their primary efforts aim to reduce traction energy demand, replace diesel, and limit the impact of electrified overhead infrastructures. From a system-level perspective, the integration of alternative energy sources on board rail vehicles has become a popular solution among rolling stock manufacturers. Surveys are made of many recent realizations of multimodal rail vehicles with onboard electrochemical batteries, supercapacitors, and hydrogen fuel cell systems. The ratings, technical features, and operating data of onboard sources are gathered for each application, and a comparison among different technologies is presented. Traction system architectures and energy-control strategies of actual multimodal units are explored and compared with literature research. Moreover, the maturity and potential of recent technologies and alternative topologies of power converters for multimodal traction systems are discussed. Ultimately, onboard storage systems are compared with other solutions for energy-saving and catenary-free operation, with particular focus on their current techno-economic attractiveness as an alternative to diesel propulsion.

Addis Ababa, the capital of Ethiopia, inaugurated the first electrified light rail transitsystem 4 years ago in September 2015, which makes it the first of its kind in sub-Saharan and eastern African countries. The railway line has a total length of 34.25 km with 39 passenger stations and 19 traction substations. Currently, the performance of the traction power supply system degraded severely due to the existence of harmonics in the traction network. Realizing the above problem, the harmonic analysis of Addis Ababa light rail transit electrified power supply system is presented. The analysis is performed on one of the substations called ‘Lideta’ rectifier substation. To this end, mathematical modelling and analysis of the traction main components such as the catenary, the traction transformer, the traction rectifier and the load have been done. Finally, MATLAB simulation has been performed, and the result comes with a significant reduction in harmonic distortion, which is far below the 5% limits of IEEE standard.

To improve the carrying capacity, double pantographs are normally used to collect the electric current from the catenary. The mechanical wave excited by the leading pantograph affects the contact of the trailing pantograph and the contact wire, which usually deteriorates the current collection quality. To address this issue, a steady arm damper is developed in this work to reduce the wave intensity caused by the leading pantograph. The catenary is modelled by Absolute Nodal Coordinate Formulation. The numerical simulations indicate that the steady arm damper with certain values reduces the contact force variation of the trailing pantograph. But overlarge damping may behave as a hard spot and aggravates the interaction performance. The acceptable steady arm damping should be lower than 300 Ns/m. The optimal value of the steady arm damping coefficient varies with the train speed. The realistic damping ratio should be determined based on the operating speed of a railway line. Based on the simulation results, several realistic steady arm dampers are developed, which are placed between the cantilever and the end of the steady arm. An experimental test is conducted to investigate the effect of the steady arm damper on the reduction of vibration caused by the dropping sinker. The experimental results demonstrate that the steady arm damper can reduce the mechanical wave amplitude and eliminate its effect on the trailing pantograph.

Performance enhancement of a powertrain DC–DC converter is provided using a current-controlled magnetic device, the variable inductor (VI). The VI is composed of two groups of windings, main and auxiliary. The auxiliary winding is used to regulate the permeability of the magnetic core over a wide range of load variations. To regulate the saturation level of the magnetic core and avoid postsaturation operation of the power inductor, an appropriate level of auxiliary winding current is needed. To this end, a simple and dynamic strategy is proposed to estimate the auxiliary winding currents of the VI. The proposed approach is validated using simulation studies of a large-scale VI-based powertrain DC–DC converter. The results reveal the significance of the proposed approach in continuous regulation of the magnetic property of the power inductor core, enhancing powertrain DC–DC converter performance by up to 13.70% and reducing stress on switching devices by 17.87%. Furthermore, energy source current variation is reduced by 6.73%, leading to reduced stress on energy storage systems.

The increase in the numbers of electric vehicles (EVs) is seen as an upgrading of the existing vehicles for various reasons. This calls for an in-depth analysis of the heart of these vehicles—the motor. A motor in an electric vehicle propulsion system is a crucial component that has the ability to affect the efficiency, weight, cost, reliability, power output and performance. Hence a detailed comparative study, that compares the existing types and topologies of various motors, is the need of the hour. The various motors that can be used in electric traction, namely DC, induction, switched reluctance, permanent magnet brushless AC motors and permanent magnet brushless DC motors, are reviewed in view of their capabilities with respect to EV propulsion. A detailed review is presented of existing motors and the application of power electronic techniques to EVs, and recommendations for some new designs of brushless DC motors. These include permanent magnet hybrid motors, permanent magnet spoke motors and permanent magnet inset motors.

When driving a 32-m long multi-set rubber-tire transit in a manual driving mode, it is easy for the driver to feel tired due to the massive concentration, and it is hard to manually operate in a narrow and twist gauge. The authors introduce a six-axle coordinated automatic all-wheel steering control system and its design method is based on the visual perception and the geometric relationship. First, the functions of the two subsystems of the full-axle automatic steering control system are introduced. One subsystem is a path tracking control system and the other subsystem is a trajectory following the control system. Secondly, the theoretical principles of the two control systems are introduced in detail. Then, the controller design method of the two subsystems is introduced. Finally, the simulation results of Trucksim and MATLAB/Simulink are compared with the actual vehicle test data to test the controller’s perception and the follow-up control effect. It can be concluded that the gap between the platform and the train is kept between a relatively 10∼20 cm narrow when the train pulls in and out of the station. When the train runs at a high speed, it is stabilised at 72 km/h, and the lateral deviation from the virtual track centreline is controlled within ±15 cm.

The most viable option to achieve the goals of saving energy and protecting the environment is to replace conventional vehicles with hybrid electric vehicles (HEVs). In HEVs, the operational characteristics of an internal combustion engine (ICE) and an electric motor (EM) are different from each other and thus require an adaptive control strategy to achieve higher fuel economy along with smooth operation and better performance of the vehicle. An energy management control strategy is proposed for an HEV based on an adaptive network-based fuzzy inference system (ANFIS). The proposed adaptive equivalent consumption minimisation strategy decides the power to be drawn from ICE and EM based on input parameters such as the speed of the vehicle, the state of charge of the battery, the EM torque and the ICE torque. The whole system is simulated in an advanced vehicle simulator tool. The proposed non-linear controller has also been tested for real-time behaviour using a field-programmable gate array–based MicroLabBox hardware controller to compare its performance against existing controllers. The authors compared the fuel economy obtained using the proposed method with several other methods available in the literature. The comparison clearly reveals that the proposed ANFIS-based method results in better optimization of energy and hence offers better fuel economy. The urban dynamometer driving schedule has been employed for this analysis.

Considering environmental conditions and reduced fuel availability, electric cars (ECs) play a vital role in many applications such as consumer cars and short-distance transportation. This paper proposes a detailed dynamic modelling of battery, motor, and inverter developed for the design of an EC. In addition, an improved controller is developed with a different geometrical method using the sensitivity gain of the current sensor and tachometer to assure the optimal performance of the EC. For achieving linear vehicle operation and improved stability, a system transfer function model is designed by considering various uncertainties such as force acting on the car, wheel, road, and wind speed conditions. To offer better regulation and excellent tracking operation of the EC, a combined proportional–integral–derivative controller-based outer-speed and inner-current control approach is suggested to regulate the nonlinear parameters for different driving profile applications. The proposed designed control approach and system model are tested using two input conditions such as step and driving profile inputs through MATLAB/Simulink software, and performance is analysed through various open-loop and closed-loop test scenarios.