Utilization Of Braking Energy Research Articles

Capacity configuration optimization of regenerative braking energy utilization system for electrified railways based on power sharing and energy storage

The full utilization of regenerative braking energy (RBE) within the railway traction power supply system (TPSS) is of great significance for railway energy conservation and power grid safety. The traditional railway traction power supply system adopts a segmented structure, and achieving efficient utilization of RBE between adjacent traction substation (TS) is a challenge. This paper proposes an RBE utilization system (RBEUS) based on railway power regulator (RPC) and hybrid energy storage system (HESS), which achieves efficient utilization of RBE between adjacent TS and maximum demand reduction of TPSS through power sharing and energy storage. A power flow control strategy based on state machine logic is proposed, and the energy scheduling reference values of RPC and HESS under different typical operating conditions are calculated. By analyzing the mathematical relationship between the costs and benefits of RBEUS, a multi constraint RBEUS lifecycle net profit optimization model is established. The optimal capacity configuration of RBEUS is obtained by using an improved beluga whale optimization algorithm with the goal of maximizing the total net income of two TSs. The advantages of the proposed method in terms of RBE utilization and economic benefits are verified through engineering case analysis and scheme comparison.

Analysis of Regenerative Braking Energy Utilization in KfW i9000 Electric Trains on the Palur-Yogyakarta Operation

Abstract This study explores the potential assessment. of regenerative braking energy in the operation of Electric Multiple Units (EMU) on the Yogyakarta-Palur railway line, a 65.03 km. Prompted by a noticeable increase in passenger numbers in the Yogyakarta metropolitan buffer zone, the study calls for future energy management strategies, involving regenerative braking to reduce energy consumption. Utilizing a mathematical model implemented via MATLAB Simulink, the research encompasses complex train movement scenarios, considering variables such as acceleration values of 0.558 m/s2 and 1 m/s2, and deceleration values of -0.555 m/s2 and 0.36 m/s2. Speed limitations, travel patterns, and energy profiles are rigorously examined, along with incline influences, such as tangent angles of 0.0032 degrees and 0.0017 degrees. In segments like Purwosari-Solo Jebres, electrical energy consumption is quantified at 23.02 kWh, with regenerative braking energy at 1.42 kWh; in Maguwo-Brambanan, consumption is 15.28 kWh, with regenerative energy at 2.42 kWh. The peak power requirements and regenerative braking potentials were also determined, with values such as 619.9 kW and 225.7 kW, and 1785 kW and 198.2 kW respectively. The total electrical consumption for the routes from Palur to Yogyakarta and vice versa was found to be 325.52 kWh and 276.73 kWh, with energy recovery of 31.43 kWh and 26.6 kWh, and average energy recovery ratios of 9.66% and 9.61%.

Optimal operation of co‐phase traction power supply system with HESS and PV

AbstractThe co‐phase traction power supply system (TPSS) with hybrid energy storage system (HESS) and photovoltaic (PV) is proposed to eliminate the neutral section and improve the regenerative braking energy (RBE) utilization. Although the integration of HESS and PV facilitates the energy saving and cost reduction of the co‐phase TPSS, the high cost and configuration of HESS should be considered, which is the key to affect the optimal operation strategy of co‐phase TPSS. Here, the optimal operation strategy of co‐phase TPSS with HESS and PV is proposed to design the HESS configuration, recycle RBE and improve power quality. The proposed model aims to minimize the total system cost, including HESS investment cost, electricity cost and operation and maintenance cost. Moreover, the proposed model is formulated as a mixed integer linear programming by employing linearization approaches. Finally, case studies verify that the 29.2% cost reduction rate is achieved and the three‐phase voltage unbalance meets the standard requirements.

Multi-objective online driving strategy optimization for energy storage tram considering battery life

Compared with the traditional overhead contact grid or third-rail power supply, energy storage trams equipped with lithium batteries have been developed rapidly because of their advantages of flexible railway laying and high regenerative braking energy utilization. However, trams may face expensive battery replacement costs due to battery degradation. Therefore, this paper proposes a multi-objective optimization method for the tram's driving strategy to reduce operational energy consumption and extend battery life. The method describes the optimization problem as second-order cone programming (SOCP). It uses the interior point algorithm for fast solving, thus obtaining the theoretical optimal speed trajectory in real-time. This feature enables the method to be applied online. To verify the effectiveness and robustness of the proposed method, we conducted simulations under actual operating conditions. The simulation results show that the proposed multi-objective optimization method can extend the battery life by 40 % compared to the single-objective optimization method for energy saving. As a result, the total cost of the whole life cycle is reduced by 6.54 %. Furthermore, this online optimization driving strategy method can effectively deal with unexpected conditions during the actual operation of the tram to ensure the secure operation, punctual arrival, and precise parking of trams. Finally, the effectiveness of the proposed method is further verified by a hardware-in-the-loop (HIL) test.

Power Flow Control-Based Regenerative Braking Energy Utilization in AC Electrified Railways: Review and Future Trends

Power Flow Control-Based Regenerative Braking Energy Utilization in AC Electrified Railways: Review and Future Trends

Power Sharing and Storage-Based Regenerative Braking Energy Utilization for Sectioning Post in Electrified Railways

Power Sharing and Storage-Based Regenerative Braking Energy Utilization for Sectioning Post in Electrified Railways

Research on regenerative braking control of electric vehicles based on game theory optimization.

The energy-efficient, clean, and quiet attributes of electric vehicles offer solutions to conventional challenges related to resource scarcity and environmental pollution. Consequently, thorough research into harmonizing energy recuperation during braking, enhancing vehicle stability, and ensuring occupant comfort in electric vehicles is imperative for their effective advancement. The study introduces a regenerative braking control strategy for electric vehicles founded on game theory optimization to enhance braking performance and optimize braking energy utilization. Develop a regenerative braking control approach based on the dynamic model of an electric vehicle equipped with hub motors. Employing game theory, we establish participants, control variables, strategy sets, benefit functions, and constraints to optimize the coefficient K for regenerative braking. The efficacy and superiority of the control strategy model are validated through joint simulations using Matlab/Simulink and AVL Cruise. Research findings indicate: (1) Speed tracking error remains below 3% in both NEDC and CLTC-P simulations, underscoring the effectiveness of the dynamic model and control strategy devised in this study. (2) The energy recovery rate achieved by the game theory-based optimization strategy surpasses that of the Cruise self-contained strategy and fuzzy control strategy by 18.06% and 4.5% in the NEDC simulation, and by 13.48% and 3.85% in the CLTC-P simulation, respectively. The adhesion coefficient curves implemented on the front and rear axles, derived from the game theory optimization control strategy, closely approximate the ideal adhesion coefficient curve, leading to a substantial enhancement in the car's braking stability. The degree of jerk magnitude regulated by the game theory optimization strategy consistently falls within the ±3 m/s³ threshold, resulting in a considerable enhancement in the comfort of vehicle occupants. These outcomes underscore the efficacy of the game theory-based optimized control strategy in enhancing energy recovery, braking stability, and comfort throughout the braking process of the vehicle.

Metro timetable optimization for improving regenerative braking energy utilization efficiency

The train generates regenerative braking energy (RBE) during braking. When the RBE generated by the braking train is too large to be absorbed and utilized, the OCS voltage will rise rapidly. It may even exceed the rated voltage threshold, resulting in hidden dangers for driving safety. How to use RBE efficiently and reasonably has become a hot issue in recent years. This paper presents a metro timetable optimization method for multi-train operation to improve the RBE utilization efficiency of trains. Firstly, an energy-saving multi-objective model for multi-train operation is established, which takes the total energy consumption and travel time as the objective functions and the dwell time and departure interval as the constraints. Then, the genetic algorithm (GA) is used to generate the composition sequence of dwell time and departure interval, and the multi-node nonlinear model is used to calculate the total energy consumption of the metro line. Finally, Guangzhou metro line 7 is selected as an example to illustrate the effectiveness of the developed optimization model. The results show that the energy consumption of the whole line can be effectively reduced by adjusting the dwell time and departure interval. Meanwhile, the timetable optimization model with GA has better energy-saving effects by comparative analysis.

Analysis and Control of Cascaded Energy Storage System for Energy Efficiency and Power Quality Improvement in Electrified Railways

Energy-efficient and grid-friendly railway power system is critical for the sustainable development of electrified railways. In this paper, a cascaded energy storage system (CESS) is investigated for energy efficiency and power quality improvement of the railway power system. First, the detailed operation principles of the CESS for multiple control objectives, including regenerative braking energy (RBE) utilization, reactive power compensation, and negative sequence current suppression, are analyzed. On this basis, a hierarchical power flow control strategy is developed for achieving the power flow management and control of multiple objectives for CESS. Specifically, a multi-objective power flow management strategy is designed in the system layer to allocate the power references for the CESS under sufficient and insufficient capacity scenarios. In the sufficient capacity scenario, the power references are directly obtained by the operation principles. In the insufficient capacity scenario, the power references are allocated through a three-stage optimization method considering the power shaving rate, grid power factor, and grid imbalance degree. Subsequently, the power references from the system layer are tracked in the converter layer to achieve power flow control. Finally, the effectiveness of the proposed hierarchical power flow control strategy is verified through experimental results. The results show that the proposed CESS can achieve superior performance on RBE utilization and power quality improvement under complex operating conditions in electrified railways.

Regenerative Braking Energy Utilization Analysis in AC/DC Railway Power Supply System With Energy Feedback Systems

In the power supply system with energy feedback system (EFS)s, the energy from EFS (WF) will flow to rectifiers, which is circulation flow (CF). However, the efficiency of CF between substations has been rarely studied. Besides, the relationship between the train operation and regenerative braking energy (RBE) utilizing efficiency is not clear. In this paper, the energy flow structure of the AC/DC railway power supply system including CF is established. In the double-train system, promoting CF when the trains’ distance is long can be beneficial to power utilization efficiency. Chengdu Metro Line 9 is analyzed as the multi-train system based on the iterative AC/DC power flow algorithm. The key to energy saving includes reducing the energy consumption of on-board resistance and the DC traction network loss. Compared with the catenary and rail system, the fourth-rail system can promote system energy efficiency by 23.5% at most. The CF and energy fed to main substations counts for less than 2% and 8% of WF. When the headway time is short, RBE should be avoided feedback to EFS, while the feedback power of EFS should be advocated when the headway time is long. The results can help guide the operation of urban rail to save energy.

Research on the Multi-Mode Composite Braking Control Strategy of Electric Wheel-Drive Multi-Axle Heavy-Duty Vehicles

Electric wheel-drive multi-axle heavy-duty vehicles have the characteristics of strong maneuverability and good passability, thereby they are widely used in heavy equipment transportation. However, current research on the composite braking of multi-axle heavy-duty vehicles is rare, which is not conducive to improving braking performance and braking energy utilization efficiency. This work proposes a multi-mode composite braking control strategy for the five-axle distributed electric wheel-drive heavy-duty vehicle. Firstly, given the differences in braking dynamics between two-axle vehicles and multi-axle vehicles, the brake dynamics characteristics of multi-axle vehicles are analyzed, and the vehicle dynamics model of multi-axle vehicles is constructed. Next, a multi-mode composite braking control strategy including a fully electric braking state and hybrid electro–hydraulic braking state is proposed in order to improve the braking energy recovery and braking stability. Finally, a hardware-in-the-loop simulation system is established, and the single-braking conditions and China heavy-duty commercial vehicle test cycle-heavy truck (abbreviated as CHTC-HT) are conducted to verify the performance of the braking control strategy. The results indicate that the recaptured braking energy and braking stability are significantly increased by applying the control strategy proposed in this work.

Analysis of voltage unbalance and mitigation of circulating power in bilateral co-phase traction system

The primary aim of this paper is to analyse and mitigate the problems inherent in adopting bilateral co-phase traction network on Indian Railways. The reason for adopting bilateral co-phase traction network is to enhance regenerative braking energy (RBE) utilization in the railway traction network. There are two inherent problems in adopting bilateral co-phase traction configuration. First, it may lead to increase in the Voltage Unbalance factor (VUF) as single-phase loading by trains is effectively doubled across the same phases. Second, and more importantly, it may lead to flow of circulating power, under no load conditions, where power shall flow from leading voltage traction sub-station to lagging voltage traction sub-station. This may offset any advantage due to improved RBE utilization. This paper demonstrates through simulation, using realistic data from Indian Railways, that VUF stays within limits for bi-lateral traction configuration. It is important to mention that improved RBE utilization also plays a role in reducing VUF when there is no feedback of RBE to the grid. For the second problem, this paper takes inspiration from a control scheme existing in literature to adapt it to the proposed scenario. This scheme shows that it is possible to limit the power angle within 0.5˚ and thereby minimising circulating power.

Pareto Optimization of Energy-Saving Timetables Considering the Non-Parallel Operation of Multiple Trains on a Metro Line

In light of reducing train operation energy consumption while maintaining the passenger service level for creating sustainable urban rail transit systems, we address a non-parallel train timetabling problem considering regenerative braking energy utilization and the non-parallel operation of multiple trains on a metro line via a newly proposed multi-objective timetable (MOT) optimization model and an evolutionary algorithm based on NSGA-II. The optimization objectives of the MOT model are to find satisfactory energy-saving timetables on the Pareto frontier by minimizing the total travel time of passengers and minimizing the net energy consumption of trains. An improved multi-objective evolutionary algorithm based on NSGA-II is constructed to generate the optimal arrival and departure times at each station for each train running in a non-parallel operation mode. This study tests the feasibility of the proposed optimization method via an empirical case using the data collected from the Yizhuang Line of the Beijing metro systems in China. The simulation results show that the proposed optimization method satisfies both the energy utilization and passenger service levels along a Pareto front. The MOT improves the overall effectiveness of regenerative braking energy utilization by 29.88% in comparison with the original timetable; it reduces the net operation energy consumption by 44.86% relative to the travel-oriented timetable (TOT); and it reduces the total passenger travel time by 27.18% compared with the energy-oriented timetable (EOT).

Optimization of high-speed train timetable based on regenerative braking energy utilization

Optimization of high-speed train timetable based on regenerative braking energy utilization

Timetable optimization for maximization of regenerative braking energy utilization in traction network of urban rail transit

Timetable optimization is one of the effective solution methods for urban rail transit to achieve energy-saving. Previous studies on timetable optimization only focused on the transfer and utilization of mechanical energy, which did not consider the exchange of energy and line losses in the traction network. Therefore, this paper constructs a cross-substation energy transmission and utilization model taking into account the characteristics of the actual traction power supply systems. An overlap current method is presented to increase the utilization of regenerative braking energy (RBE) of trains and reduce the energy supply of the traction substation by considering the line loss, which is achieved by compensating the current generated by accelerating and braking trains in the substation. The compensation current can be maximized by adjusting the dwell time to achieve energy-saving. The traction power supply systems with highly nonlinear dynamic characteristics are linearized to construct a mixed-integer linear programming (MILP) model, which utilizes the utilization of RBE as the objection and dwell time as the variable. The method of maximum compensation current is verified by numerical examples based on Beijing Batong Line. The results show that the energy-efficient of the method is greatly improved compared with the method of maximizing the overlap time between the accelerating train and the braking train.

Hierarchical Energy Management of Networked Flexible Traction Substations for Efficient RBE and PV Energy Utilization Within ERs

The particular split-phase traction power system of AC electrified railways (ERs) restricts its regenerative braking energy (RBE) utilization and photovoltaic (PV) penetration. Networked flexible traction substation (FTSS) operation is a promising paradigm to address this restriction. Therefore, this paper proposes a networked FTSS system architecture that ties adjacent FTSSs via unified power flow controllers (UPFC) at sectioning posts (SPs), which matches the technical characteristics of split-phase ERs obtaining the lower capacity requirement. Correspondingly, a real-time hierarchical energy management strategy is designed. The networked FTSS management level optimizes the energy cooperation among FTSSs, i.e., the exchange power at SPs. It aims at maximizing the global RBE and PV energy utilization and shaving the maximum demand of each FTSS. At the individual FTSS management level, each FTSS autonomously regulates the power outputs of the local back-to-back converter and energy storage system to maximize the local RBE and PV energy utilization and improve the local power quality issues. These two energy management levels operate independently with different time scales, making the networked FTSS system have good extensibility and reliability. Finally, the performance of the proposed scheme is verified via hardware-in-the-loop tests.

Integrated energy‐efficient optimization for urban rail transit timetable

AbstractThe energy‐efficient optimization of the train timetable should be carried out on the basis of meeting passenger demand and determining the train operation plan. This paper proposes an integrated energy‐efficient optimization framework for the train timetable. Firstly, two energy‐efficient optimization strategies for this problem are proposed: inter‐station running time allocation and regenerative braking energy utilization. The first strategy aims to reduce the traction energy consumption, realized by selecting the profile based on a given set of speed profiles for each inter‐station sector when ensuring a stable travel time of train routing. The second strategy is intended to fully utilize the regenerative energy feedback from braking trains, realized by setting the departure time of trains based on a small‐range headway adjustment. Then, an integrated energy‐efficient optimization model of the timetable is developed and solved using the genetic algorithm. Finally, a case study of the Guangzhou Metro Line 8 is presented to verify the effectiveness of the method. The results show that the utilization rate of regenerative braking energy in the optimized timetable increases by 8.60%, and the total energy consumption decreases by 9.52%. Regenerative energy utilized roughly doubles during peak hours and increases more than twice as much during off‐peak hours.

Integrated Regenerative Braking Energy Utilization System for Multi-Substations in Electrified Railways

This article proposes an integrated regenerative braking energy utilization system (RBEUS) to improve regenerative braking energy (RBE) utilization in electrified railways. The proposed RBEUS uses a traction substation energy storage system and two sectioning post converters to achieve coordinated RBE utilization in three consecutive traction substations via power-sharing and storage, and the power quality can also be improved. A hierarchically coordinated control strategy is developed based on the operation principle to provide real-time power management and control for the RBEUS. In the system layer, a centralized power management strategy is designed for operation mode management and active power command generation. It uses a sequential quadratic programming-based algorithm to solve the objective function to achieve optimal RBE utilization under different operation modes. In the converter layer, local controllers of the RBEUS enable converters to respond to the active power commands from the system layer and reactive power commands generated by themself for power flow control. The effectiveness of the proposed RBEUS is comprehensively verified by using a hardware-in-the-loop experiment. Besides, a comparison analysis of the proposed RBEUS and literature methods is conducted to testify the superiority of the RBEUS. The feasibility of RBEUS implementation is also discussed from fault protection and economy.

Optimal planning of hybrid energy storage systems in traction power supply system with railway power conditioner

AbstractThe railway power conditioner (RPC) is a promising technology to improve the regenerative braking energy (RBE) utilization and power quality of the traction power supply system (TPSS). The hybrid energy storage systems (HESS) play a key role in the economic operation of TPSS due to the high cost of the system. The capacity and power of HESS are the critical issues affecting the system performance and cost. Therefore, a hierarchical energy management model is proposed to optimize the HESS sizing and the scheduling of TPSS with RPC. At the master level, a nonlinear mathematical model is built to minimize the HESS cost, which includes capital cost, replacement cost, and recovery cost. At the slave level, considering voltage unbalance as a constraint, a mixed‐integer linear programming model is established to minimize the electricity cost of railway operation. In order to solve the hierarchical nonlinear programming problem, an improved particle Swarm optimization (PSO) algorithm with a GUROBI solver embedded is proposed. Finally, the results show that the 14.08% cost reduction is achieved, and the standard limit value of voltage unbalance is satisfied.

Self-Excited, Electromagnetic Braking and Heating System for Electric Buses

New energy vehicles usually recover the braking energy and store it back into the battery using the electric motor. Such a regenerative braking system improves the vehicle mileage. In the process of regenerative braking, all components of the system dissipate a great amount of energy, especially in winter. On the other hand, heating the vehicle's cabin consumes electric energy, further reducing its autonomy. Based on this, we propose a novel Self-excited, electromagnetic Braking and Heating System (SBHS), to solve problem of the driving range dramatic decline of electric bus when heating the bus cabin in winter. The system converts the kinetic energy of the electric bus into heat, via electromagnetic braking, and uses it to warm the vehicle's cabin in winter. Our system improves the conversion efficiency of regenerative braking. We present the structure of the system and calculate the air gap magnetic density using the magnetic circuit method. We develop the braking heat generation model and obtain the heat generation performance at different speeds using J-MAG. To improve the braking energy utilization efficiency, we design a braking force distribution strategy based on a fuzzy control system. We also characterize the braking and built-in generator performances in a test bench, and obtain the braking and heating characteristic at different speeds. We implemented our EBHS and installed on a test electric bus. The test records include SOC, temperature inside the vehicle and distance. The results show that the SBHS can provide both sufficient braking torque for the vehicle and heat energy for the cabin.