Voltage Unbalance, Power Factor and Losses Optimization in Electrified Railways Using an Electronic Balancer

Unbalanced currents, low power factor and high losses contribute to increasing the bill infrastructure managers must pay to the TSO/DSO operator that supplies electric energy to the railway system. Additionally, if regenerative energy coming from braking regimes is not allowed to be injected into the grid or even is penalized when it occurs, then the optimization of those parameters must be pursued. One of the possible measures that can be taken to counteract those phenomena is the installation of electronic balancers in heavy loaded substations in order to optimize the interface to the three-phase electric grid. This paper shows the benefit of such use taking examples from real conditions and realistic simulations assumed equivalent to field measurements.

Fast and efficient CO2 absorption in non-aqueous tertiary amines promoted by ethylene glycol

With the catalytic induction of EG, anhydrous DMEA shows CO absorption performance via chemical binding and physical storage under normal pressure. Among the absorbents, pure DMEA can hardly absorb CO directly but when the zwitterionic alkylcarbonates are formed between CO and DMEA-EG which can be characterized by C NMR and FTIR, the absorption rate of CO will be improved at this time. An increasing the CO loading as the mass fraction of EG in DMEA-EG, 90wt.% EG captures up to 0.72 mol/mol. The amount of chemically bound and physically stored is directly dependent on temperature, within the range of 293 to 323K, an absorption-regeneration cycle can be formed in a closed vessel because of the zwitterion DMEA-EG-CO is unstable at the higher temperature. In other words, DMEA-EG-CO can be easily regenerated upon appropriate depressurization or heating, corresponding thermodynamic calculations prove that the regenerative energy of DMEA-EG-CO is 25.49kJ/mol.

The LabTogo-Project

A joint project between West African Science Service Center on Climate Change and Adapted Land Use (WASCAL), the University of Lomé and the German Biomass Research Center (Deutsches Biomasseforschungszentrum; DBFZ) was initiated in 2020. The project aims at evaluating alternative and regenerative energy sources for rural areas and creating the basis for successful implementation. In three different work packages, therefore, biomass potentials should be quantified, technologies should be examined with regard to their suitability and - in the case of biogas application - a research structure, pilot biogas laboratory, should be created that is necessary to enable the sustainable implementation of technologies.

Elevator Regenerative Energy Applications with Ultracapacitor and Battery Energy Storage Systems in Complex Buildings

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.

Sit-To-Stand and Stand-To-Sit Energetics for Assistive Devices and Robotics Design

This research presents the development of a Sit-to-Stand and Stand-to-Sit model for regenerative energy recovery with applications in orthoses, protheses and humanoid robot design. Sit-to-Stand and Stand-to-Sit are routine activities and are crucial pre-requisites to walking and running. Determining design parameters for devices which can aid people to perform these activities in an effective manner is a key goal here. MapleSim was used to simulate a 1/10-scale multi-domain model and a nonlinear torque controller was used to control the trajectory profiles of the Sit-to-Stand-to-Sit gait. The model allows accurate simulation of hardware components for use in a future robot. This study addresses the usage in regenerative braking towards sit-to-stand-to-sit and the relationship between Coriolis/centrifugal torque components to inertial and gravitational torque components. This study examines the level of regeneration at ankle, knee and hip. Furthermore, it examines the significance of Coriolis and centrifugal versus inertial and gravitational components of a nonlinear controller in order to determine if these components would be needed in a real robot controller. By applying joint trajectories from human trials it was found that the regenerative effect in the robot model was most significant in the hip and least significant in the ankle. Furthermore, we determined that the Coriolis and centrifugal terms were approximately 1% of the inertial and gravitational terms in the applied nonlinear controller, making them insignificant. We also determined upper bounds for gearing in the joints such that battery autonomy is maximized without encountering motor saturation and inaccurate trajectory following. From these findings, we recommend that robot designs neglect the Coriolis and centrifugal terms and that regenerative hardware be prioritized at the hip.

Sit-To-Stand and Stand-To-Sit Energetics for Assistive Devices and Robotics Design

This research presents the development of a Sit-to-Stand and Stand-to-Sit model for regenerative energy recovery with applications in orthoses, protheses and humanoid robot design. Sit-to-Stand and Stand-to-Sit are routine activities and are crucial pre-requisites to walking and running. Determining design parameters for devices which can aid people to perform these activities in an effective manner is a key goal here. MapleSim was used to simulate a 1/10-scale multi-domain model and a nonlinear torque controller was used to control the trajectory profiles of the Sit-to-Stand-to-Sit gait. The model allows accurate simulation of hardware components for use in a future robot. This study addresses the usage in regenerative braking towards sit-to-stand-to-sit and the relationship between Coriolis/centrifugal torque components to inertial and gravitational torque components. This study examines the level of regeneration at ankle, knee and hip. Furthermore, it examines the significance of Coriolis and centrifugal versus inertial and gravitational components of a nonlinear controller in order to determine if these components would be needed in a real robot controller. By applying joint trajectories from human trials it was found that the regenerative effect in the robot model was most significant in the hip and least significant in the ankle. Furthermore, we determined that the Coriolis and centrifugal terms were approximately 1% of the inertial and gravitational terms in the applied nonlinear controller, making them insignificant. We also determined upper bounds for gearing in the joints such that battery autonomy is maximized without encountering motor saturation and inaccurate trajectory following. From these findings, we recommend that robot designs neglect the Coriolis and centrifugal terms and that regenerative hardware be prioritized at the hip.

Optimal Approach to Improving the Utilization of Regenerative Energy Considering Power Profile

Urban rail transit (URT) develops rapidly in modern cities, and its energy efficiency attracts extensive attention. The utilization of regenerative energy (URE) is an important method for energy-efficient operation of URT. Regenerative braking is an energy recovery mechanism that slows down a moving train by converting its kinetic energy into electric energy. The electric energy can be utilized for other trains to accelerate in a cooperative way. To take full advantage of the regenerative energy, an energy calculation method which considers regenerative braking power to optimize the timetable is proposed in this paper. First, four operating modes of URE are defined and an integer programming model is formulated. Second, a branch and bound algorithm is designed to solve the optimal timetable in different scenarios. Third, the model is evaluated based on the operation data from the Yanfang Line, Beijing Metro, China. For peak hours, the results illustrate that the proposed method can significantly improve URE by 73.7% compared with the original timetable. Also, URE can be improved by 46.3% for off-peak hours. Finally, the comparison between the proposed method and the method based on the kinetic energy theorem is given. The simulation results illustrate that the proposed method could increase URE by 29.7% and 9.9% for peak and off-peak hours scenarios, respectively, in comparison with the method based on the kinetic energy theorem.