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Hybrid Electric Vehicles (HEVs) are a promising option to reduce transportation emissions while the adoption of pure electric vehicles is still low in many countries. This study aims to examine the factors that affect the fuel economy and the emission performance of a HEV compared to a Conventional Vehicle (CV) with a traditional Internal Combustion Engine (ICE) under different real driving conditions. In order to analyze the energy efficiency of the HEV, this paper proposes an experimental method based on empirical data to estimate the equivalent Fuel Consumption (FC) of the energy supplied by the Electric Motor (EM). Then this parameter is used to compare the fuel efficiency of the HEV and the CV, which have similar specifications, in order to demonstrate that the hybrid configuration has better fuel economy than the combustion engine configuration. The test vehicles' performance is evaluated in different Driving Cycles (DCs) in Hanoi. Moreover, the time and the distance with zero-emission rates and regenerative energy efficiency are presented to assess the HEV's energy management strategy and environmental benefits in different Hanoi's driving scenarios. [ABSTRACT FROM AUTHOR]

Formulating energy policies at national, European, and global levels is extremely challenging. The move away from fossil fuels is associated with a variety of technological, economic, and social implications, each of which is subject to dynamic changes and societal scrutiny and can hardly be predicted with certainty. Therefore, a fact-based assessment for the path to a sustainable green energy future is sought out in this paper, using the road-based mobility sector of the Federal Republic of Germany as an example. The analysis performed in this paper is built on publicly accessible, reputable sources like DESTATIS and EUROSTAT. In addition, some very simple calculations were made, e.g., on the potential for wind and photovoltaic energy within Germany. Such an analysis needs to start with the overall energy consumption of any one country. A basic assumption of the paper is that the energy system of the future will be based to a large extent on electricity and its storage in chemical energy. It is assumed that, in addition to hydrogen, liquid energy sources will play a significant role due to the simplicity of their logistics and the subsequent implications on cost. Examples of green, electricity-based fuels with great potential are methanol, methane, and ammonia. Additionally, biomass plays an important role, either for direct use as a fuel or as a source of non-fossil carbon. Today, biofuels, i.e., biodiesel and bioethanol, deliver the largest contribution to climate protection in the EU transport sector. The main goal—the reduction of greenhouse gas emissions—often collides with geopolitical circumstances or national political necessities. This includes, for example, the current world market situation and its national impacts caused by the Russian attack on Ukraine. The prospect for a green, sustainable, and defossilized energy supply are discussed in this context. The paper concludes that a defossilized world energy supply and trade based on renewable electricity and its derivatives, eHydrogen and refuels, and on biomass, is feasible. [ABSTRACT FROM AUTHOR]

Abstract A novel three-phase traction power supply system is proposed to eliminate the adverse effects caused by electric phase separation in catenary and accomplish a unifying manner of traction power supply for rail transit. With the application of two-stage three-phase continuous power supply structure, the electrical characteristics exhibit new features differing from the existing traction system. In this work, the principle for voltage levels determining two-stage network is dissected in accordance with the requirements of traction network and electric locomotive. The equivalent model of three-phase traction system is built for deducing the formula of current distribution and voltage losses. Based on the chain network model of the traction network, a simulation model is established to analyze the electrical characteristics such as traction current distribution, voltage losses, system equivalent impedance, voltage distribution, voltage unbalance and regenerative energy utilization. In a few words, quite a lot traction current of about 99% is undertaken by long-section cable network. The proportion of system voltage losses is small attributed to the two-stage three-phase power supply structure, and the voltage unbalance caused by impedance asymmetry of traction network is less than 1‰. In addition, the utilization rate of regenerative energy for locomotive achieves a significant promotion of over 97%.

Electrical vehicles have the ability to partially recover some kinetic energy during braking. Kinetic energy is transformed into electric energy, which is fed to the battery by the control system and stored there for further use. The aim of this paper was to analyse the levels of energy recovered by an electric vehicle during braking at various speeds and with different braking intensities. The first phase of testing consisted of vehicle braking tests in real-life conditions. The registered speed profiles were then used as input data for the simulation software. The authors have also analysed the effect of the state of charge of the battery and of the vehicle's load on the amount of energy recovered during braking. The performed simulation tests demonstrated that the level of recovered energy is significantly affected by the initial braking speed and by the force of pressure applied to the brake pedal. The amount of recovered energy is less affected by the state of charge (SOC) of the battery and by the vehicle's load. Energy regeneration during braking is currently an important research topic. The efficiency of an electric vehicle depends on the range, which can be extended thanks to the additional energy recovered during braking maneuvers. The presented preliminary simulation results are intended to assess the level of energy recovery in electric vehicles. The authors are aware that a full, comprehensive analysis requires additional research using electric vehicles that will verify the results presented in the paper. [ABSTRACT FROM AUTHOR]

Improving energy efficiency is the most important goal for buildings today. One of the ways to increase energy efficiency is to use the regenerative potential of elevators. Due to the special requirements of elevator drives, energy storage systems based on supercapacitors are the most suitable for storing regenerative energy. This paper proposes an energy storage system consisting of a supercapacitor bank and a bidirectional six-phase interleaved DC/DC converter. The energy savings achieved by the proposed system were investigated through simulation tests. The proposed system was modeled considering all physical constraints. A simulation model of the existing faculty elevator system was created in PLECS and verified with field measurements. Reliable results were ensured by using the verified simulation model and considering all physical constraints. The operation of the proposed energy storage system was tested under various conditions. In addition, the simulation model of the elevator system with the proposed energy storage system was tested using the elevator traffic data obtained from the measurements. The simulation results show the effectiveness of the proposed energy storage system and that significant energy savings can be achieved. [ABSTRACT FROM AUTHOR]

The article presents a new approach to forecasting producer gas composition. Thermochemical treatment of biomass was presented as an effective method of producing flammable gas. The methods of predicting the gas composition of the generator are described, and then its efficiency depends on the device's parameters. In order to create a method for forecasting gas composition, the authors' works were used as the basis on which the energy characteristics of the gases obtained were assessed. It was assumed in this paper that it is essential to understand the influence of each parameter on the energy characteristics of the gas. It made it possible to optimize the composition and predict thermal characteristics. This article presents the results of experimental studies on biomass gasification and a mathematical model based on Gibbs free energy. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) regenerative suspension system can not only achieve excellent comprehensive suspension performance but also effectively recover and utilize vibration potential energy, which has been a research hotspot in the field of vehicle engineering. In this paper, for the 1/4 vehicle’s MR regenerative suspension system parallel with a tubular permanent magnet linear motor (TPMLM), the dynamic model of the MR semi-active suspension system and the TPMLM finite element model are established separately to form a joint simulation platform. The simulation analysis of the comprehensive suspension performance and regeneration performance under different road excitations is performed. The results show that installing TPMLM does not change the natural resonance frequency of the suspension system, which ensures good driving comfort and handling stability. At the same time, it has considerable regeneration power. This research can provide a reference for the stability analysis and popularization of the vehicle’s MR regenerative suspension system.

The stationary supercapacitor energy storage system (SCESS) is one of effective approaches for the utilization of train's regenerative braking energy in urban rail systems. In this paper, the capacity configuration of SCESSs, the no-load voltage of substation, the control of onboard braking resistors and train operation diagrams are considered comprehensively. Based on the equivalent circuit model, the effects of traction power system parameters on the energy transmission between powering trains, braking trains and SCESSs are analyzed, and the relationships between the train operating parameters and system energy consumptions are revealed. A multi-variable synthetic optimization method is proposed to optimize the SCESS capacity, train operation diagrams and traction power system parameters collaboratively. In order to reduce the search space and improve the efficiency of the optimization algorithm, a hierarchical multi-objective optimization model is established, based on which the design variables and the control variables are optimized iteratively. And as the traffic density has a great impact on the regenerative braking energy distribution of the system, the optimization objective function fully considers the frequency distribution of headways throughout the day. Combined the Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) with the traction power flow simulator, the flowchart of the two-stage optimization algorithm is designed, and the pareto set of the multi-objective problem is obtained. The advantages of reducing system energy consumptions and configuration cost under the proposed algorithm are verified based on case studies of Beijing Batong Line. [ABSTRACT FROM AUTHOR]

Improving energy efficiency is the most important goal for buildings today. One of the ways to increase energy efficiency is to use the regenerative potential of elevators. Due to the special requirements of elevator drives, energy storage systems based on supercapacitors are the most suitable for storing regenerative energy. This paper proposes an energy storage system consisting of a supercapacitor bank and a bidirectional six-phase interleaved DC/DC converter. The energy savings achieved by the proposed system were investigated through simulation tests. The proposed system was modeled considering all physical constraints. A simulation model of the existing faculty elevator system was created in PLECS and verified with field measurements. Reliable results were ensured by using the verified simulation model and considering all physical constraints. The operation of the proposed energy storage system was tested under various conditions. In addition, the simulation model of the elevator system with the proposed energy storage system was tested using the elevator traffic data obtained from the measurements. The simulation results show the effectiveness of the proposed energy storage system and that significant energy savings can be achieved.

Energy-efficient train operation is regarded as an effective way to reduce the operational cost and carbon emissions in metro systems. Reduction of the traction energy and increasing of the regenerative energy are two important ways for saving energy, which is closely related to the train timetable and driving strategy. To minimize the systematic net energy consumption, i.e., the difference between the traction energy consumption and the reused regenerative energy, this paper proposes an integrated train operation approach by jointly optimizing the train timetable and driving strategy. A precise train driving strategy is presented and the timetable model considers the headway between successive trains, the distribution of the trip time, and passenger demand in this paper. In addition, a distributed regenerative braking energy model is proposed, based on which the integrated optimization model is formulated. Then, a two-level approach is proposed to solve the problem. At the driving strategy level, the train control problem is transferred into a multi-step decision problem and the Dynamic Programming method is introduced to calculate the energy-efficient driving strategy with the given trip time. As for the timetable level, the trip times and headway of trains are optimized by using the Simulated Annealing algorithm based on the results of dynamic programming method. The timetable optimization level balances the mechanical traction energy of multi-interstations and the amount of the reused regenerative energy such that the net mechanical energy consumption of the metro system is minimized. Furthermore, two numerical examples are conducted for train operations in the peak and off-peak hours separately based on the real-world data of a metro line. The simulation results illustrate that the proposed approach can produce a good performance on energy-saving. [ABSTRACT FROM AUTHOR]

In metro systems, a tactical train schedule with the rolling stock circulation plan aims to determine the movements of all physical trains. To utilize the regenerative energy as much as possible, this paper proposes an integrated model to simultaneously generate the optimal train schedule and rolling stock circulation plan, in which the brake-traction overlapping time at stations is maximized. In particular, our model rigorously considers the train turn-around constraints, train circulation constraints, and dynamic passenger demands to tackle the train loading capacity constraints. To eliminate the effect of non-linear constraints, we reformulate the original model into its equivalent linear model that can be efficiently solved by linear programming solvers. Finally, the numerical experiments based on Beijing Yizhuang Metro Line are implemented to demonstrate the effectiveness of our proposed model. [ABSTRACT FROM AUTHOR]

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Certain applications of power electronics for railway vehicle traction systems and fixed installations are reviewed and future possibilities considering technical and social trends around railway industry are mentioned in this paper. First of all, some particularities of railway load and traction power supply system are summarized as problems to be solved by power electronics technologies. Such technologies for fixed installations and vehicle traction systems are presented and future possibilities for higher performance, minimization, and improved resilience of railway system are pointed out. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In this study, a supercapacitor (SC)/battery hybrid energy storage unit (HESU) is designed with battery, SC and metal–oxide–semiconductor field‐effect transistors. Combined with the operation of brushless DC motor (BLDCM) and the output mode of the proposed HESU, the vector combinations that are suitable for different operation states of the BLDCM are analysed. By using reasonable vector combinations, the HESU can utilise the SC to store the regenerative energy from BLDCM during the braking process and assist the battery to power the motor during the acceleration process. Also, the designed HESU can achieve high‐voltage output by connecting the SC and battery in series, to suppress the commutation torque ripple of BLDCM in the motoring state. Finally, the correctness of the theoretical analysis and the feasibility of the proposed method are verified by the experiment results. [ABSTRACT FROM AUTHOR]

Abstract In 2006, the first Lithium-ion battery in Japan was installed in traction power supply system by the West Japan Railway Company and now more than 20 energy storage systems have already been installed in traction power supply system in Japan. In this article, the recent Japanese trends of regenerative energy utilization are summarized not only in DC railway but also in AC railway. We, East Japan Railway Company, have installed three energy storage systems for DC railway and one railway static power conditioner (RPC), not energy storage system, for AC railway for regenerative energy utilization. The effects of these systems are also shown quantitatively in this paper.

A multi-objective optimization strategy considering regenerative braking was proposed. Taking into account the impact of relative velocity, driver style, and road adhesion conditions, a variable time headway strategy was first proposed. Then, a multi-objective optimization strategy in adaptive cruise system was designed under the model predictive control framework. The incremental adaptive model predictive control with time-varying weights was constructed to be used as the upper controller, and slack variable was used to process the constraints. The constraints of regenerative braking were analyzed, and a new brake force distribution strategy based on multi-source information fusion was proposed to further optimize the economy. On the AMESim & Simulink co-simulation platform, a battery electric vehicle model was built and the proposed strategy was simulated. The results showed that, comparing to the constant-weight strategy, the proposed strategy had better robustness, which could rapidly and timely adjust the control target and guarantee the safety, comfort, economy, and following. The multi-source information braking force distribution strategy can guarantee several goals of the system while improving the economy. It can regenerate more braking energy, and the braking regenerative energy contribution increased by 5.68%. [ABSTRACT FROM AUTHOR]

Due to the dramatic growth of the global population, building multi-story buildings has become a necessity, which strongly requires the installation of an elevator regardless of the type of building being built. This study focuses on households, which are the second-largest electricity consumers after the transportation sector. In residential buildings, elevators impose huge electricity costs because they are used by many consumers. The novelty of this paper is implementing a Hybrid Energy Storage System (HESS), including an ultracapacitor Energy Storage (UCES) and a Battery Energy Storage (BES) system, in order to reduce the amount of power and energy consumed by elevators in residential buildings. The control strategy of this study includes two main parts. In the first stage, an indirect field-oriented control strategy is implemented to provide new features and flexibility to the system and take benefit of the regenerative energy received from the elevator’s motor. In the second stage, a novel control strategy is proposed to control the HESS efficiently. In this context, the HESS is only fed by regenerated power so the amount of energy stored in the UC can be used to reduce peak consumption. Meanwhile, the BES supplies common electrical loads in the building, e.g., washing machines, heating services (both boiler and heat pump), and lighting, which helps to achieve a nearly zero energy building.

In subway systems, kinetic energy can be converted into electrical one by using regenerative braking systems. If regenerative energy (RE) is fully used, the energy demands from power grid can be dramatically reduced. Since energy storage systems usually have a high cost, they are not considered in this work. Thus, RE has to be immediately utilized by accelerating trains; otherwise, it is wasted into heat via resistors. Timetable optimization methods are often used to coordinate accelerating and braking trains at a station, such that RE can be optimally used by the former. To improve RE utilization (REU) in a subway line, we propose a timetable optimization problem and establish its mathematical model. Many realistic constraints with the decision variables, i.e., headway time and dwell time, are considered. Then we design an improved artificial bee colony (IABC) algorithm to solve the problem. Several numerical experiments are conducted based on the actual data from a subway line in Beijing, China. The correctness of the mathematical model and effectiveness of IABC are shown by comparing it with commercial software CPLEX and a genetic algorithm, respectively. The impact of the decision variables on REU is analyzed, which helps to improve the timetable currently used in this subway line. We also test the robustness of the optimized timetable when certain disturbance takes place. [ABSTRACT FROM AUTHOR]

• The operation of an EAB is described by dynamic models and battery model. • Effects of input parameters on the electric consumption of the EAB are investigated. • A study for electric power generation is conducted using a modeling approach. • An experimental study for motion and electric consumption of the EAB is conducted. A study is conducted to examine the motion, dynamic and electric consumption characteristics of an electric assisted bicycle based on the effects of certain operating conditions and structural parameters. Simulation models for operation of the electric assisted bicycle, including dynamic models of the electric assisted bicycle and battery models, are established. These simulation models are solved by MATLAB-Simulink to provide the operating characteristics of the electric assisted bicycle. Based on the established mathematical models, the motion, dynamic and electric consumption of the electric assisted bicycle are analyzed and optimized under the effects of slope, bicycle mass, wheel radius, crank length, and sprocket transmission ratio. The simulation results show that the dynamic performance and electric consumption of the electric assisted bicycle are significantly improved by reducing the bicycle mass, wheel radius, and increasing the sprocket transmission ratio. The dynamic performance and electric consumption are optimal when the slope grade, bicycle mass, wheel radius, crank length, and sprocket transmission ratio are 0%, 12 kg, 0.32 m, 0.17 m and 3.43, respectively. A study for using the regenerative energy generated during the downhill movement of the electric assisted bicycle to create electrical power is presented under the effects of rider mass and slope angle. An experimental study is also conducted to examine the motion and electric consumption characteristics of the electric assisted bicycle under real operating conditions. This study shows agreement between simulation and experimental results at the same initial conditions. [ABSTRACT FROM AUTHOR]

In this paper, a decentralized energy management strategy (EMS), which is based on a modified droop control, is proposed for a fuel cell (FC)/supercapacitor (SC)-based auxiliary power unit (APU) of a more electric aircraft. The proposed EMS is able to split the load power automatically into low- and high-frequency components and allocate them to the FC and SC units, respectively. Since the proposed EMS is fully decentralized, it features high flexibility and scalability. Furthermore, the proposed strategy is not only suitable for extending the service life of the system because the protection and recovery of the state-of-charge of the SC have been considered in doing the energy management, but also can make the system accommodate the regenerative power in a lossless way. The operational principle of the proposed strategy, system design details and performance analysis are elaborated, followed by which experiments based on a 3 kW FC/SC-APU are conducted to verify its validity. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes an active bus voltage limiter with a modified modulation strategy for bi-directional power flow applications. When the motor is braking, the regenerative energy raises the DC bus voltage. Additional shunt resistors are usually used to dissipate the regenerative energy, which is a waste. The active rectifiers, which are also mentioned as PWM (Pulse Width Modulation) rectifiers, can transfer the regenerative power to the power grid but the cost is high and not economic, especially when the regenerative power is comparatively low. This paper investigates the zero-sequence current produced by the active bus voltage limiter and then presents a modified space vector modulation strategy to effectively suppress the zero-sequence current and keep the unity power factor. The analysis about the control strategy of the topology is carried out. And the algorithms for regenerative applications are discussed. An industrial prototype is built to verify the configuration. Highlights • The proposed limiter can transfer the regenerative energy to the power grids. • The model of the zero-sequence current generated in the applications is established. • A modified SVPWM is proposed and the zero-sequence currents are suppressed. • The strategy proposed can be further used when many inverters run in parallel. • An industrial prototype is built and has been used in elevators. [ABSTRACT FROM AUTHOR]

In 2006, the first Lithium-ion battery in Japan was installed in traction power supply system by the West Japan Railway Company and now more than 20 energy storage systems have already been installed in traction power supply system in Japan. In this article, the recent Japanese trends of regenerative energy utilization are summarized not only in DC railway but also in AC railway. We, East Japan Railway Company, have installed three energy storage systems for DC railway and one railway static power conditioner (RPC), not energy storage system, for AC railway for regenerative energy utilization. The effects of these systems are also shown quantitatively in this paper. [ABSTRACT FROM AUTHOR]

Nowadays, electric railway system is known as an efficient and environmentally friendly solution for transportation system. Many developing countries have been expanding their railway systems to support the growth of transport demand. Even though railway system can utilize energy efficiently, its operation still requires bulk of energy. Therefore, management of multiple energy sources is an important issue for railway planning and operation. The advent of modern railway technologies provides regenerative braking system which can recover considerable energy from brake operation. Management of regenerative energy becomes a key for enhancing railway operation. This paper presents a strategy for utilizing regenerative energy in urban railway system by adjusting train operating schedule and employing wayside energy storage system. Optimizing train schedule aims to increase the degree of regenerative energy usage and applying super capacitor as temporary energy storage will manage the surplus of regenerative energy. By integrating appropriate train scheduling and energy storage system, energy management can be more flexible and effective leading to improvement of energy-saving operation. The numerical case study of Bangkok Rapid Transit System was performed and evaluated to reflect the improvement of utilizing regenerative energy. [ABSTRACT FROM AUTHOR]

Focusing on service quality improvement and energy consumption reduction in an urban rail transit network, this paper proposes a multi-objective programming model to jointly optimize timetables through considering total passenger trip time and operational energy consumption. The time-variant quantities are adopted to represent the dynamic passenger demands, with which passenger boarding, alighting and transferring process are taken into consideration for calculating total travel time and variation of in-service train mass. To effectively measure the total energy consumption, three parts of energy consumption are specified, including traction energy consumption, auxiliary energy consumption and usage of regenerative energy. In particular, the regenerative energy is allowable to simultaneously reuse by traction trains on the same line or in supply regions of different lines nearby the same transfer station. A compromise for service quality and energy consumption from the viewpoint of system optimization is especially proposed through adjusting headways in different lines. To effectively solve the proposed model, a tabu search algorithm is designed to obtain near-optimal timetables of the whole transit network. With the practical data of Line 5, Line 10 and Yizhuang Line in Beijing rail transit network, the effectiveness of this model and solution method is demonstrated by a series of numerical experiments. [ABSTRACT FROM AUTHOR]

Maximizing regenerative energy utilization is an important way to reduce substation energy consumption in subway systems. Timetable optimization and energy storage systems are two main ways to improve improve regenerative energy utilization, but they were studied separately in the past. To further improve energy conservation while maintaining a low cost, this paper presents a strategy to improve regenerative energy utilization by an integration of them, which determines the capacity of each Wayside Energy Storage System (WESS) and correspondingly optimizes the timetable at the same time. We first propose a dual-objective optimization problem to simultaneously minimize substation energy consumption and the total cost of WESS. Then, a mathematical model is formulated with the decision variables as the configuration of WESS and timetable. Afterwards, we design an ϵ -constraint method to transform the dual-objective optimization problem into several single-objective optimization problems, and accordingly design an improved artificial bee colony algorithm to solve them sequentially. Finally, numerical examples based on the actual data from a subway system in China are conducted to show the effectiveness of the proposed method. Experimental results indicate that substation energy consumption is effectively reduced by using WESS together with a correspondingly optimized timetable. Note that substation energy consumption becomes lower when the total size of WESS is larger, and timetable optimization further reduces it. A set of Pareto optimal solutions is obtained for the experimental subway line—based on which, decision makers can make a sensible trade-off between energy conservation and WESS investment accordingly to their preferences.

This paper proposes a super capacitor energy storage-based modular multilevel converter (SCES-MMC) for mine hoist application. Different from the conventional MMCs, the sub-modules employ distributed super capacitor banks, which are designed to absorb the regenerative energy of mine hoist and released in the traction condition, so as to improve energy utilization efficiency. The key control technologies are introduced in detail, followed by analysis of the configuration and operation principles. The feasibility of the proposed SCES-MMC topology and the control theory are also verified. Simulation results show that SCES-MMC can adapt to the variable frequency speed regulation of the motor drive, which shows good application prospects in the future for mediumand high-voltage mine hoist systems. [ABSTRACT FROM AUTHOR]

This paper introduces a DC/AC converter, which can be connected in parallel with a diode rectifier for regenerative applications. The DC/AC converter is supposed to transmit regenerative energy to the power grid when a motor is braking. Isolation transformers are not needed in the topology, which can reduce the size and cost. An analysis of the zero-order current existing in the system is carried out. In addition, algorithms to minimize the zero-order current, control the power factor and keep the DC bus voltage stable are discussed. A 55kW industrial prototype is built to verify the proposed analysis and control strategies. [ABSTRACT FROM AUTHOR]

In the daily operation of metro systems, the train scheduling problem aims to find a set of space-time paths for multiple trains that determine their departure and arrival times at metro stations, while train operations are in charge of selecting the best operational speed to satisfy the punctuality and operation costs. Different from the most existing researches that treat these two problems separately, this paper proposes an integrated approach for the train scheduling problem on a bi-direction urban metro line in order to minimize the operational costs (i.e., energy consumption) and passenger waiting time. More specifically, we simultaneously consider (1) the train operational velocity choices that correspond to the energy consumption of trains on each travelling arc, and (2) the dynamic passenger demands at each station for the calculation of total passenger waiting time in the planning horizon. By employing a space-time network representation in the formulations, this complex train scheduling and control problem with dynamic passenger demands is rigorously formulated into two optimization models with linear forms. The first model is an integer programming model that jointly minimizes train traction energy consumption and passenger waiting time. The second model, which is formulated as a mixed-integer programming model, further considers the utilization of regenerative braking energy on the basis of the first model. Due to the computational complexity of these two models, especially for large-scale real-world instances, we develop a Lagrangian relaxation (LR)-based heuristic algorithm that decomposes the primal problem into two sets of subproblems and thus enables to find a good solution in short computational time. Finally, two sets of numerical experiments, involving a relatively small-scale case and a real-world instance based on the operation data of Beijing metro are implemented to verify the effectiveness of the proposed approaches. [ABSTRACT FROM AUTHOR]

The Korean government enacted the “Special Law for Improving Air Quality of Metropolitan Area” in 2003. According to this plan, Korean government plan to lower the concentrations of PM10 and NOx to 40 μg/m3 and 22 ppb, respectively, by 2014. In this study, we analyze emission reduction strategies to lower their concentration. Emission reduction for the supply of mass energy and regenerative energy are compared with several scenarios. According to the results, 713 t/y of NOx and 165 t/y of PM10 will be reduced by enhancing the number of households supplied by local heating and air conditioning. And also 5 t/y of PM10 and 312 t/y of NOx will be reduced by replacing conventional energy with solar energy by 2014.