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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.

A rapidly growing demand and shortage of electric energy require mankind to efficiently use it, recuperate and store it from the existing system, when possible, for further applications whenever the need arises. Electric trains figure among big energy consumers and among different railway transportation services; light rail transit trains are characterized by frequent stoppings to entrain and detrain passengers. In their operation, traction drives are made to keep on braking in order to meet their service requirements between closely spaced passenger stations. The modern service braking system used is regenerative braking, which acts as an electric energy generator during the braking period. The objective of this paper is to estimate the magnitude of regenerative energy that can be recuperated as a percentage of train energy consumption on East-West (Ayat to Tolhailoch) and West-East (Tolhailoch-Ayat) directions of Addis Ababa Light Rail Transit. Mathematical equations have been used to calculate the energy consumed between stations followed by the quantification of regenerative energy at each passenger station. Considering the current average running speed (24km/h) of the line, it resulted that 26.31% and 28.18% of energy consumption for East-West and West-East directions respectively are saved through regenerative braking energy recuperation. From the above results, it was observed that the magnitude of regenerative energy strongly depends on the speed at which the train is running and the efficiencies of inverter and traction induction motor.

Our research group is developing an electric orthosis for assisting hemiplegic patients to walk. Lack of electrical power is a problem for this orthosis, so, as an improvement to this device, we are developing a generator that generates power efficiently from the rotation of joints while the patient walks. In this report, the outline and the improvement of the controller circuit are described. The circuit connects two boost chopper circuits in parallel. By shifting one of the switching phases of their circuits by 180°, the battery voltage output can be increased to 17% more than that of a conventional circuit.

Obtaining an effective sorting method for train operating conditions is the premise for studying the optimization method of renewable energy utilization in the operation of urban rail trains. But there are few studies in this field. So that, in this paper, firstly, based on the given running time of the train, the construction rules of the running condition sequence of the interval train are given for the interval of different speed limiting types. Then, based on the train operating condition sequence solution set obtained by the construction rules, the regenerative energy utilized in the traction phase of each sequence and the regenerative energy utilized in the braking phase are used as ranking indices, and the interval number is used to express the uncertainty of the two ranking indices. The interval numbers of all solutions are obtained and sorted by the TOPSIS method based on entropy weight, and the sequence values of all train operating conditions corresponding to the interval are obtained. Finally, an example is given to illustrate the practical application of this sorting method.

A 48V active clamp resonant single-ended primary inductor (SEPIC) converter has advantages, which are switch voltage stress suppression and achieving zero-voltage switching (ZVS). Therefore, it is effective in renewable energy systems that can provide a 48V dc bus. This paper clarifies how the active clamp resonant SEPIC converter is affected by whether the active clamp circuit is connected to the input or output side and its performance mechanism is clarified.

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.

Purpose. To develop the fuzzy model of distribution of excess regenerative energy in traction and external power supply systems allowing to exercise effective operation of the power equipment. Relevance. For effective distribution of excess regenerative energy in systems of electric transport, as well as for systems equipped with stationary stores of energy and inverting traction substations with regulators of output voltage it is necessary to solve a number of the problems with high degree of uncertainty demanding taking into account a set of random factors such as the modes of power lines and traction loadings. These factors have to be considered in operation for choosing the rational modes of energy stores, inverters and regulators of voltage on buses of substations to provide the rational conditions for energy regeneration on electric transport. Scientific novelty. The control system of energy storage devices, inverters and traction substation output voltage regulators, designed on the basis of fuzzy logic, can provide the necessary conditions for the regeneration on electric transport on sections with a shortage of traction power consumption and allows to optimize the distribution of excess braking energy of transport vehicles. It is achieved by determining the rational relationship between the components of the excess current of regeneration in real time, which can ensure a minimum of power losses of regenerative energy in traction and external power supply systems. Practical importance. The use of the developed approach is effective under the conditions of incomplete information received by measurement systems and on the basis of additional studies it can allow to minimize rated capacity of stores, inverters and traction substation output voltage regulators that could reduce the costs of modernization of existing sections and electrification of new electric transport systems.

The worldwide four warmest years (2015-2018) since weather records began and a new peak CO2 concentration in the atmosphere [2] highlight the urgency of reducing the anthropogenic CO2 emissions. Only with the expansion of power generation from regenerative energy sources, a drastic reduction of CO2 emissions is possible. Due to the fluctuating nature of these sources, new challenges arise. The storage of larger amounts of energy needs to be realized by gaseous or liquid energy carriers [6].

Electrified guided vehicles typically face routes having a large number of acceleration and braking phases. The braking energy, since the feeding line presents nonreversible electrical feeding substations, can be recovered in the presence of other nearby vehicles. To improve braking energy recovery, one or more storage systems can be positioned along the track. Analysis of effectiveness for the considered solution requires time-domain simulation models, to be created through suitable simulation general-purpose languages or specialised languages/software. In this paper, three different tools for the considered existing tramway were developed, and the main examined characteristics have been compared to each other. Then, analysis of output results was also performed, demonstrating the real cost-effectiveness of introducing one storage device on the considered tramline in operation.

The development of land transportation has effectively contributed to countries’ economic and social development. Roads, rails and vehicles have come into widespread use in transporting things from one location to another on land. However, much energy is dissipated in traditional land transportation, and this energy is worthy of being recovered. Many researchers in recent decades have presented different types of energy harvesting systems to harness this dissipated energy. Regenerative energy harvesting systems can convert dissipated energy into electricity for different applications. This paper is a comprehensive review of energy harvesting technologies for different applications in the land transportation. First, the commonly used energy harvesting technologies in land transportation are summarized. Second, different energy harvesting systems are presented in terms of designs, simulations, and experiments. Third, a common analysis of energy harvesting technologies is conducted to calculate and simulate the performance of these systems. Also, a comparison of the presented energy harvesting systems is conducted in various ways. Then different applications and energy utilizations of the energy harvesting systems are summarized. Moreover, research gaps and technical difficulties that remain unresolved are discussed, and some recommendations are made, which aim to be helpful for further research.

To improve driving ability of electric vehicle, a braking regenerative energy recovery of electric vehicle was designed and the structure of it was introduced, the energy recovery efficiency of whole system was defined and a highly efficient control strategy was put forward, then it was embedded into the simulation of ADVISOR2002. The recovery efficiency of the system was up to 60%, the electric vehicle energy recovery efficiency was effectively improved.

Regenerative energies are generated by regenerative braking of train. Regenerative energies might cause the problem of power quality such as the voltage drop and malfunction of the power conversion device in the electric railway system. For these reasons, many researches have studied to solve these problems. In this paper, we modeled DC electric railway system based on the solid state transformer that is composed of voltage source converter (VSC) and bi-directional DC-DC converter for controlling the regenerative energy. In order to verify the performance of the proposed electric railway system, electric railway system is modeled by using real time simulator OP5600. In addition, the controller of solid state transformer is implemented by using DSP, TMS320F28335.

This paper aims at determining the influential factors affecting regenerative braking energy in DC rail transit systems. This has been achieved by quantitatively evaluating the dependence of regenerative energy on various parameters, such as vehicle dynamics, train scheduling, ground inclination and efficiency of the electrical devices. The recuperated power and energy have been presented by a mathematical model, comprising of a set of empirical forms, which allows for thorough analysis. A detailed simulation model of a typical DC-traction system has been developed to validate the developed empirical forms. The results verified the validity of the proposed mathematical model, and demonstrated the significance of the examined parameters on the regenerative power and energy of a train during a complete cycle. Knowledge of the parameters impacting the magnitude of regenerative energy should maximize the potential of harnessing regenerative energy.

In 2006, the first Li-ion battery was installed in traction power supply system by West Japan Railway Company and now more than 20 energy storage systems have already installed in traction power supply system in Japan. In this article, the recent trend for regenerative energy utilization is summarized not only in d.c. railway but also a.c. railway. We, East Japan Railway Company, have installed 3 energy storage systems for d.c. railway and one railway static power conditioner for a.c. railway for regenerative energy utilization. The effects of these systems are also shown quantitatively in this paper.

Owing to the reduction in the peak power of a DC railway subsystem, many studies on energy storage system (ESS) applications have received attention. Each application focuses on improving the efficiency and addressing regulation issues by utilizing the huge regenerative energy generated by braking-phase vehicles. The ESS applications are widely divided into installation on a vehicle or in a substation, depending on the target system characteristics. As the main purpose of the ESS application is to reduce the peak power of starting-phase vehicles, an optimized ESS utilization can be achieved by the operating at the highest peak power section. However, the weight of an entire vehicle, including those of the passengers, continuously changes during operation; thus, considering the total power consumption and the discharging point is difficult. As a contribution to the various storage device algorithms, this study deals with ESS on board vehicles and introduces an ESS operating plan for peak-power reduction by investigating the weight of a train on a real-time basis. This process is performed using a train-performance simulator, and the simulation accuracy can be increased because the weight in each phase can be adopted in the simulation.

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 medium- and high-voltage mine hoist systems.

Recent research has shown great potential in energy efficiency optimization by harvesting regenerative energy of industrial robots. This paper presents further insight into how dependent regenerative energy is on the mass of the robot tool, as well as how the total regenerative energy is distributed between various robot links.

We, East Japan Railway Company, have already installed three energy storage systems in d.c. railway power supply system around Tokyo area for regenerative energy utilization and are now constructing new regenerative inverter system at Tokyo Station. In this paper, advantages and disadvantages of those systems will be compared. Furthermore, the examples of load waveforms of traction power supply system and distribution line system at Kajibashi Substation will be shown to discuss feasibility of regenerative energy utilization.

In this paper, effect of recharging power by using ESS(Energy Storage System) was investigated when ESS was applied to the train. The recharging power was analyzed and measured. Also, by applying ALVT algorithm, effective recharging and discharging were studied. By using this process, recharging and discharging of the super capacitor were improved which led to enhancing the use of recharging power from the urban Railway vehicles.

This paper discusses the control strategy for energy management in railway transit network with wayside (substation) supercapacitor (SC) energy storage system (ESS). Firstly, the structure of the wayside energy storage system is introduced. Secondly, the model of energy storage system is built and the control strategy is described. Thirdly, in order to estimate the required energy storage system, a useful method is proposed to predict the instantaneous regenerative energy magnitude which is delivered to each substation. Finally, the ESS configuration for each substation is determined. A simplified mathematical model of the whole metro network is established and the main features of the control strategy are developed. Numerical simulations show the efficacy of suggested control strategy and the energy saving obtained for railway transit network.

In this paper a novel regenerative dual-braking strategy is proposed for utility and goods delivery unmanned vehicles on public roads, which improves their ability to recover regenerative energy and consequently improves the fuel use of parallel hybrid powertrain configurations for land unmanned vehicles where the priority is not comfort but extension of their range. Furthermore, the analysis takes into account the power-handling ability of the electric motor and the power converters. In previous research, a plethora of regenerative braking strategies have been reported; in this paper, the key contribution is that the vehicle electric regeneration is related to a fixed braking distance in relation to the energy storage capabilities specifically for unmanned utility-type land vehicles where passenger comfort is not a concern but pedestrian safety is of critical importance. Furthermore, the power converter capabilities of the vehicle facilitate the process of extending the braking time by introducing a variable-deceleration profile. The proposed approach has therefore resulted in a regenerative algorithm which improves the energy storage capability of the vehicle without considering the comfort since this analysis is applicable to unmanned vehicles. The algorithm considers the distance as the key parameter, which is associated with safety; therefore, it allows the braking time period to be extended, thus favouring the electric motor generation process while maintaining safety. This method allows the vehicle to brake for longer periods rather than for short bursts, hence resulting in more effective regeneration with reduced use of the dual system (i.e. the caliper–stepper motor brake system). The regeneration method and analysis are addressed in this paper. The simulation results show that the proposed regenerative braking strategy improved the ability of the hybrid powertrain configuration to recover energy significantly. The paper is also supported by experimental data that verify the theoretical development and the simulation results. The two strategies developed and implemented utilize a constant braking torque and a constant braking power. Both methods were limited to a fixed safety-based distance. Overall, the results demonstrate that the constant-braking-torque method results in better energy-based savings.

China is a big agricultural country, which had many kinds of biomass resources. Biomass energy belongs to clean energy, it was available to achieve zero co2 emissions and substitute fossil fuels such as coal, oil and gas to be an important energy. Through the transformation of 35t/h coal-fired CFB boiler, which based on material and circulated carrier, burning biological energy, changed boiler from consuming one-time energy to the regenerative energy, which saved coal and prevented waste from directly emitting into the atmosphere to pollute the environment. It would save energy and increase the local farmers additional income by sell stem, which followed the trend of the national development strategy. The test data show that: this transformation of boiler is very successful, indicate that we can transform some original polluted boiler which consume coal to some degree and provide some experimental methods for these transformations.

A hybrid railway traction system with fuel cells (FC) and electric double-layer capacitors (EDLC) is discussed in this paper. This system can save FC costs and absorb regenerative energy. A method for designing FC and EDLC on the basis of the output power and capacitance, respectively, has not been reported, although their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such a design method is presented along with a train load profile and an energy management strategy. The design results obtained using the proposed method are verified by performing numerical simulations for a running train. These results reveal that the proposed method for designing the EDLC and FC on the basis of the capacitance and power, respectively, and using a method for controlling the EDLC voltage, is sufficiently effective in designing efficient EDLC and FC of hybrid railway traction systems. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 47–54, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22395

To make railway transportation more efficient, utilization of recuperation energy in d.c. traction power supply system is actively discussed in Japan. We, East Japan Railway Company, have already introduced two Lithium ion battery systems at Haijima Substation since 2013 and at Okegawa Substation since 2014. They contribute to reduce total traction energy supply about 5–8%. In a.c. traction power supply system, on the other hand, it is rarely discussed to make use of recuperation power because it is not an issue compared with d.c. traction power supply system in many cases. We installed, however, RPC, railway static power conditioner, at Ushiku sectioning post for recuperation energy utilization in 2014. In this paper, the difference between d.c. traction power supply system and a.c. traction power supply system from the point of view to utilize recuperation energy and its future prospect in a.c. traction power supply system are discussed.

One of the initiatives toward traction energy saving on the railways is effective utilization of the regenerative energy. Greater efficiency in energy use is achieved through the installation of the energy storage system by discharging the energy depending on the load situation. The energy storage systems are usually used flywheel, nickel-metal hydride batteries, lithium-ion batteries, electric double layer capacitor (EDLC), etc. East Japan Railway Company also installed two energy storage devices using lithium-ion batteries at Haijima and Okegawa substations. This paper describes the installed results of these energy storage systems. Furthermore, the installation effect was estimated using two methods at Okegawa substation.

This paper deals with a control strategy of an active power filter module (APFM) which functions energy-saving by reusing regeneration energy of a traction motor for the lift load. The APFM can be used by additionally connecting dc-link of a usual inverter for motor of the lift load. In motoring mode, the deadbeat current control for APF function is used to mitigate delay factors depending upon data volume and interrupt processing of DSP associated with sampling time. The proposed method determines the operation mode and performs the control algorithm corresponding to each mode. The simulation is implemented to verify the proposed control method for APFM.

A brake energy regenerative strategy was introduced in this paper after the analysis of brake torque distribution and maximum battery charge power within the ECE regulation scope. Studying on efficiency of regenerating energy under different driving conditions,the models and simulations of the energy regenerating strategy were obtained based on the Mat lab Simulink environment. By considering the comfort of passenger, under the ECE NEDC cycles, a 16% reclaim of braking regenerative energy was attained.

In this paper, the stationary super-capacitors are used to store a metro network regenerative braking energy. In order to estimate the required energy storage systems (ESSs), line 3 of Tehran metro network is modeled through a novel approach, in peak and off-peak conditions based on the real data obtained from Tehran metro office. A useful method is proposed to predict the maximum instantaneous regenerative energy which is delivered to each station before applying ESS and based on that the ESS configuration for each station is determined. Finally, the effectiveness of the proposed ESS is confirmed by economic evaluations and benefit/cost analyses on line 3 of Tehran metro network.

An analytical approach for the management of regenerative energies in multiaxis servo-motor-drives, which can operate in parallel packaging/assembly/manufacturing lines, is presented in this paper. This energy management is achieved through a proper time-coordination between the speed commands of multiaxis drives. Moreover, the proposed approach significantly limits the peak value of the ac input current in these systems. It is mathematically proved that a time-delay can significantly increase the amount of utilized regenerative energy, and consequently decreases the amount of dissipated energy. In this paper, a set of closed-form formulas is developed for different acceleration-deceleration time ratios, where motor losses are neglected. The findings of this investigation were experimentally verified using a two-axis permanent-magnet motor-drive system, and the results are presented in this paper. The experimental results are in remarkable agreement with the developed closed-form formulas.

A hybrid railway traction system with fuel cells (FCs) and electric double layer-capacitors (EDLCs) is discussed in this paper. This system can save FC costs and absorb the regenerative energy. A method for designing FCs and EDLCs on the basis of the output power and capacitance, respectively, has not been reported, even though their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such design method is presented along with a train load profile and an energy management strategy. The design results obtained using the proposed method are verified by performing numerical simulations of a running train. These results reveal that the proposed method for designing the EDLCs and FCs on the basis of the capacitance and power, respectively, and by using a method for controlling the EDLC voltage is sufficiently effective in designing efficient EDLCs and FCs of hybrid railway traction systems.

To reduce the environmental impact of the DC power system of the East Japan Railway Company (JR-EAST), it is important to have effective regenerative energy transfer from one train to another. In this paper, simultaneous measurements between the Yamanote Line Series E231 trains and the adjacent substations were conducted. From these measurements, the correlation between squeezing control of regenerative power in the trains and behavior of the substations was confirmed. Also, to consider minimizing the total squeezing control of regenerative power and maximizing the regenerative ratio, we studied the total of squeezing control of regenerative power and regenerative ratio on the trains from the data at the substations.

This paper deals with the power integration of large urban railway systems to improve regenerative energy utilization. Current regenerative energy utilization is low because there is no special plan for using this energy. If the railway system is integrated with other railway systems, the efficiency is expected to be improved. Through the case studies, to find the realistic effect of integrated operation, real system for the Seoul Metro lines, especially line 5 and 7, had been applied.

This paper considers the problem of revising train departure time to reduce electric power consumption of mass rapid transit (MRT) railways. The motion of a train running between stations is divided into three phases: traction, coasting, and deceleration phases. The traction phase requires high electric power to operate MRT railways. In the coasting phase, the train moves stably by consuming little or no power. The deceleration phase is a braking mode and produces some electric power called regenerated brake power owing to inertia force for the train generated In the traction and coasting phases. The regenerative energy can be used by other accelerating trains within a specific range from the train and thereby the power consumptions of train can be reduced. We developed a mixed integer programming model to solve the problem. To validate the suggested model, a computational experiment was conducted using real data from Korea Metropolitan Subway.

The paper presents the determination scheme of the power capacity and installation location for regenerative inverters in a DC 1500 V electric railway system. Using Train Performance Simulation (TPS) and Power Flow Simulation (PFS) software, loss ratios of the regenerative power in a subway line and root-mean-square values of regenerative power are calculated for each substation. According to varying the number of regenerative inverters installed, these values are calculated repeatedly and allow determining the suitable installation number, location and power capacity of regenerative inverters in a subway line. To confirm this determination scheme, the simulation results of TPS and PFS of a Seoul subway line are applied.

Effizienzsteigerung und Emissionsminderung sind notwendige Voraussetzungen und Ziele der nachhaltigen Energiesysteme der Zukunft. Dezentrale regenerative Energiesysteme werden ein starkes Wachstum erfahren. Eine Vernetzung mit den vorhandenen zentralen Systemen ist fur eine zuverlassige und uberwiegend regenerative Energieversorgung erforderlich. Microgrids sind insbesondere geeignet, um Effizienz und Leistungsbegrenzung sowie dezentrale Energieautomatisierung und -regelung wie auch Blackoutfestigkeit rasch zu entwickeln.

Two Lithium ion battery systems have already installed at practical traction substations, HAIJIMA SS and OKEGAWA SS, to utilize regenerative energy in d.c. 1.5kV traction power supply system of East Japan Railway Company. In this paper, the effect of energy storage system for energy saving by making use of regenerative energy is evaluated in detail. According to our experiences, the annual effects of energy storage systems at HAIJIMA SS and OKEGAWA SS are 400MWh/year and 600 or 700MWh/year, respectively.

To reduce the environmental impact of the DC power system of the East Japan Railway Company (JR-EAST), it is important to have effective regenerative energy transfer from one train to another. In this paper, a simultaneous measurement between a Yamanote Line Series E231 train and the adjacent substations was conducted. From these measurements, the correlation between squeezing control of regenerative power in the train and behavior of the substations was confirmed. Also, to consider minimizing the total squeezing control of regenerative power we studied the total of squeezing control of regenerative power from the data at the substations.

The goal of this paper is to analyze the performance of regenerative energy storage systems (ESS) in electric vehicles. This article presents a comparison of two different hybrid ESSs and using the Li-ion based conventional battery packs. The hybrid ESSs considered in this study combine Li-ion cells with ultra capacitors and hydraulic systems respectively. The configuration of each of these combinations is presented in this document in detail. Performance of all three ESSs for drive cycles has been compared using the Autonomie software.

As phase one of the CHIC (Clean hydrogen in European cities) project, eight Fuel Cell (FC) hybrid buses on route RV1 have been put in service in central London. One of the next steps is to assess and determine the viability of switching from conventional diesel-technology to fuel cell technology on other bus routes in London. This paper reports on a study where a laboratory sized FC hybrid system modelled on the London hydrogen bus (RV1) is used to explore potential opportunities. Specifically, this paper examines the performance and optimization of a FC hybrid propulsion solution having a smaller FC and various energy storage arrangements. The proposed design is a series hybrid system for the urban driving environment, with focus on transit buses. A Proton Exchange Membrane Fuel Cell (PEMFC) has been selected with a Super Capacitor (SC) as the energy storage technology. The hybrid propulsion system has also been simulated in PSCAD and the model validated using the laboratory sized system. Of particular focus is the control strategy of the hybrid propulsion system to optimise power delivery efficiency during operation and optimise hydrogen consumption. The paper concludes by examining how FC technology can be applied to transit buses with the model validated by experiment and evaluation of the viability of adapting the technology technically. This is a project that is being progressed and this paper will focus on simulation part of the project.

The concept of distributed energy generation in DC-microgrids is becoming more and more popular, due to the enhanced advantages of energy self-supply and minimizing of conversion losses. Based on a sewage application containing a photovoltaic system and a pump application, this paper describes the individual subsystems of a DC-microgrid. A Matlab/Simulink simulation will be presented to view the behaviour of the system with its power flows and potential of optimization. The validation of the simulation model is verified by an experimental setup and the simulation and measured results will be compared.

The ESS has been studied to use regenerative energy all over the world. Recently, In Korea, The DC 1500V ESS was installed and managed in Daejeon Metro line 1 in 2009. This paper presents the control method and tests to upgrade the energy saving rate of the DC 1500V ESS installed in Daejeon Metro line 1. It was installed and managed. And the ESS saved energy, 318,824kwh and reduced CO2, 135.15tons for 10 months. Therefore, the ESS is considered to be one of the useful devices for energy storing and recycling.

As ultracapacitors are being used for many years in applications in the fields of transportation, regenerative energy and industry recently they become more and more an important component for automotive engineers. Global pressure on car manufacturers to build low or zero emission vehicles forces designers to review energy storage systems. Therefore an ultracapacitor is used because of significant advantages compared to traditional storage systems as batteries. Besides enabling to size the primary energy system only for average power needs ultracapacitors fascinate by their robustness under challenging thermal, mechanical and electrical conditions. With these characteristics they can form a highly efficient system in combination with other energy storage systems. Maxwell Technologies offers a wide range of components which match to many applications in automotive and other engineering sectors.