Electric Transportation Systems Research Articles

Voltage Stability Analysis of General Cargo Ship Electrical System

Voltage Stability Analysis of General Cargo Ship Electrical System

Possibility of Using Petroleum Coke As Reducing Agent for V2O5 in Solid-Phase Synthesis of Li3V2(PO4)3

Nowadays, electrochemical batteries are playing an important role in the development of technology in various fields – consumer electronics, electric transport, and stationary energy storage systems. The main requirements for modern batteries are high specific energy and low cost. State of art lithium-ion batteries have the highest specific energy, but their cost is quite high, and that limits their production volume. Therefore, a relevant problem is the development of new low-cost electrode materials with a high specific energy. One of the most promising compounds for positive electrodes of lithium-ion batteries is lithium vanadium phosphate Li3V2(PO4)3. It has the same safety in operation as LiFePO4, and at the same time has a higher specific capacity of 197 mA·h/g vs. 170 mA·h/g in LiFePO4, and provides lithium-ion batteries higher average discharge voltage. The lithium-ion batteries with positive electrodes based on Li3V2(PO4)3 have an average discharge voltage of 4.1 V and with LiFePO4 have 3.3 V [1]. The main raw material for lithium-vanadium phosphate is vanadium pentoxide (V2O5). V5+ reduces to V3+ in the process of synthesis Li3V2(PO4)3. The aim of the present work was to study the possibility of using petroleum electrode coke as a reducing agent in the solid-phase synthesis of lithium vanadium phosphate Li3V2(PO4)3. The following reagents were used: Li2CO3 (>99.9%), NH4H2PO4 (>98%), V2O5 (>99%), petroleum electrode coke. The reagents were milled to a homogeneous mixture in a mortar, then pressed into pellets in a hydraulic press at a pressure of 6 tons per cm2. The synthesis was carried out at a temperature of 800 °C in a tubular furnace in an argon atmosphere for 5 hours. Electrodes of the following composition (% wt.) were made of the synthesized material: 80% Li3V2(PO4)3, 10% Super P, 10% LA-132. 1M LiPF6 in mixture of DMC:EMC:EC:PA (1:1:2:1 by vol.) was used as an electrolyte, Celgard®3501 was used as a separator, lithium metal foil (100 µm) was used as the negative electrode. On the 1st cycle, the discharge capacity of the cells was 130 mA∙h/g(Li3V2(PO4)3) for cells being cycled in the potential range of 3.0-4.2 V and 160 mA∙h/g(Li3V2(PO4)3) in the range of 3.0-4.8 V. According to obtained results, it can be concluded that petroleum electrode coke can be used as a reducing agent in the solid-phase synthesis of Li3V2(PO4)3. In order to improve the characteristics of Li - Li3V2(PO4)3 cells, it is necessary to optimize the synthesis method. This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7), Russia.

Electrolyte Additive Effects Observed By Gradient Polarity Solvent Wash

The fast evolution of electrical transportation system and smart grid desires advanced energy storage systems. Lithium-ion battery (LIB) is the primary option for energy storage in the global market, but its performance is still subject to improvement. Solid electrolyte interphase (SEI) plays a crucial role in LIB behavior, and electrolyte additives provide a convenient approach for fine-tuning the properties of SEI. It is crucial to obtain detailed structural and chemical information of SEIs and electrolyte soluble byproducts to promote mechanism understanding of the electrolyte additives and formation and function of SEI. Here, we propose to use gradient polarity solvent wash in combination with spectroscopic analysis to characterize both the composition of the electrolyte and layered structure of SEI. A series of model cells with a metal cathode, a lithium anode, and various additives are analyzed to reveal the electrolyte decomposition products in the electrolyte and the SEIs on the electrodes from these test cells.

Transformations of Urban Electric Transport in Ukraine after 1991 in the View of Transport Policy

The article presents, in a multifaceted manner, the changes that occurred in urban electric transport in Ukraine after 1991. The purpose of the article is to research the diversification of the degree and directions of development and transformation of urban electric transport systems in the context of the transport policy. The legal and financial conditions for the functioning and development of the system are discussed, and a SWOT analysis of the current situation is carried out. In order to assess the direction of the changes occurring on individual networks, a synthetic index was used, constructed on the basis of the statistical data from 25 years available. The research has shown that in 1991‒2016, in the vast majority of Ukrainian cities there was a regression in urban electric transport, the largest in the east of Ukraine. That was of a bipartite nature: in the first years it practically applied to all networks, later a polarization in cities occurred ‒ in parts of cities the situation of urban electric transport has improved slightly. In the context of numerous diagnosed problems, the challenges faced by urban electric transport in Ukraine were indicated.

Consideration of the influence of the reliability of elements of the urban electric transport system on its bandwidth

The article proposes an approach to assessing the capacity of urban electric transport, which is one of the criteria for a stable resource supply of electric traction, taking into account the reliability of the elements of its infrastructure. By introducing the operational readiness factor as an indicator of reliability, the researcher has the opportunity to assess the impact of failures of these components on the efficiency of the electric traction process, as well as to compare the compliance of the transport line infrastructure with the characteristics of the rolling stock used.

The approach to the study of the reliability of the electric transport system of the city as a complex technical system

The currently existing methods for analyzing and assessing the reliability of a technical system are mainly focused on its individual elements and do not take into account the complexity of their interactions and integration into subsystems of various hierarchical levels. When considering the issues of reliability of electric vehicles, they mainly focus on individual components: the reliability of electric traction rolling stock, the reliability of the power supply system, the reliability of the track infrastructure, etc. The article proposes an approach that allows to consider urban electric transport as a complex technical system consisting of several levels, each of which contains components directly involved in the transmission and conversion of electric power into mechanical work of rolling stock under the influence of the environment. Such an approach will allow, in particular, to assess the impact of the reliability of such individual components on the efficiency of implementation of electric traction in a complex technical system of urban electric transport.

Description of a complex technical system of urban electric transport from the standpoint of synergistic methodology

City electric transport is considered from the standpoint of a synergistic methodology in order to search for modern approaches to solving the actual problem of increasing its efficiency. The properties of the urban electric transport system are identified in their unity and interdependence in terms of synergetics. Methodological interpretations of these properties from the standpoint of an actually existing system of urban electric transport will allow determining its theoretical synergetic model.

Theory and a posteriori practical methods for calculating the reliability of electrical equipment

The determination of the current technical resource of the electric transport system is an important characteristic that allows one to define not only the current reliability of the system, but also to predict it for the future. If the maintenance of electrical equipment is carried out to restore the reliability, failure flow is not stopped, then the intensity of equipment failure will be artificially overstated. The timing of service impacts will also be overstated unsuccessfully.

Energy Management System in DC Micro-Grids of Smart Ships: Main Gen-Set Fuel Consumption Minimization and Fault Compensation

This paper proposes an energy management system (EMS) of the electrical system of a luxury ship (yacht). Starting from the analysis of the current configuration of the electric system, it proposes some solutions for its improvement, aiming at the reduction of the fuel consumption of the diesel engine (DE) driven permanent magnet synchronous generators (PMSG) and, therefore, at the reduction of the related ship polluting emissions. From the architectural side, a dc electrical distribution on-board has been adopted in place of the existing ac. Moreover, the dc micro-grid has been integrated with renewable energy sources (RES) based generators, as well as an energy storage system (ESS). From the management point of view, the proposed EMS governs the ship electric system in three working conditions: 1) regular operation; 2) DE driven PMSG fault/outage; 3) overload. During regular operation, the EMS implements the variable speed paradigm of the DE driven PMSGs on-board, permitting a reduction of the fuel consumption, and the related polluting emissions. In this phase, the ESS is exploited to minimize the speed and power transients of the DE. In case of a fault of one of the DE driven PMSGs, the ESS compensates the power missing for the entire duration of the cold start up of the auxiliary generator. In case of big overload, the ESS provides the exceeding power with respect to the rated one, thus avoiding potential micro-grid instability problems. This paper proposes also a stability analysis of the entire on-board dc micro-grid.

Retail and Wholesale Electricity Pricing Considering Electric Vehicle Mobility

We consider the operation of multiple charging network operators (CNOs), each serving a population of electric vehicle (EV) drivers who subscribe to them for charging services. The CNOs set retail prices for the charging stations they operate, which effectively control the electricity demand and queues formed at their charging stations. The stations’ electricity demand also ties the CNOs’ retail optimization problem to their position in the wholesale market of electricity, creating a coupling between the electric transportation systems and the bulk power grid, which is managed by an independent system operator (ISO). In this paper, we provide retail pricing mechanisms and iterative wholesale market-clearing algorithms that together maximize social welfare in this coupled system. Specifically, our algorithm would enable the CNO to reduce its electricity costs and the customers’ travel delays (including charging station queueing times) and the ISO to reduce societal electricity costs by tapping into the EVs’ flexibility as mobile electric loads. Our theoretical analysis relies on the application of congestion pricing techniques to a capacitated user equilibrium problem on an energy-and-time expanded transportation network model. This expanded network allows us to track the travel costs of individual EVs, including their limited battery charge, the cost of waiting in queues at public charging stations, as well as the temporally variant nature of travel times.

Energy Aware Driving: Optimal Electric Vehicle Speed Profiles for Sustainability in Transportation

This paper investigates the benefits of exploiting weather conditions for energy optimal driving. Optimization approaches are introduced that are based on the fact that weather-dependent speed profiles can save transportation energy, especially for electric transportation systems. Optimization models for both minimum transportation energy with travel time constraints and minimum travel time with transportation energy constraints are introduced and the resulting speed profiles are analyzed. Infinite dimensional optimization models are proposed for exact problem descriptions and approximate discretized convex models are derived for highly efficient solutions. The optimization tasks are formulated as a deterministic as well as a robust optimization problem, where weather conditions such as wind speed and rolling resistance effects are assumed to be known exactly or within uncertainty bounds. Simulations illustrate the utility of the proposed optimization models and demonstrate achievable efficiency improvements.

The Requirement To Increase The Quality of Power Electronics in Warships

Today's and future ship electrical systems are very different from ship electrical systems in the past. Power electronics, which are found in systems such as propulsion systems, power distribution systems, auxiliary systems, weapon systems, sonar and radar systems, is the most fundamental difference in ship design. The technical specs also vary in parallel with the development of materials used in power electronic elements. Graphics, which vary with respect to volume, yield and temperature, increases more and more in a positive manner. But, what we cannot see in the positive sense of increase in the power electronics technology is the inaccuracies that arise from experience. These faults are usually due to design faults, the interference caused by the switching elements such as IGBT, tristar and triac used in power electronics, current harmonics, voltage harmonics, malfunction of sensitive devices due to AC and DC leakage in the ship's body. To prevent this, it is necessary to develop systems using power electronic elements which will not interfere with the operation of the system but may prevent them from occurring

Evaluación Probabilística y Gestión del Riesgo de la Cargabilidad de la Red por la Puesta en Servicio del Metro de Quito considerando el Movimiento Estocástico de los Trenes Eléctricos

El presente artículo propone una metodología para evaluar el impacto de las cargas móviles (trenes eléctricos) del sistema eléctrico del Metro de Quito en la red de la Empresa Eléctrica Quito. Esta metodología, basada en simulación de Montecarlo, permite la generación aleatoria de escenarios de operación de transporte masivo considerando: el desplazamiento, consumo de energía y condiciones de operación de los trenes eléctricos. La propuesta metodológica permite la evaluación probabilística de flujos de potencia mediante funciones de densidad de probabilidad (PDF por sus siglas en inglés); y adicionalmente, propone el cálculo de índices de riesgo para medir, dado un grado de confianza, los mínimos o máximos valores esperados de nivel de carga, voltaje, entre otros factores que caracterizan el nivel de cargabilidad de una red.

Assessment of reliability of an overhead transmission line with a split back-up phase

Transmission of electrical energy is the most important component of an electric power system. Optimization, modernization of the electric power transport system, increasing the capacity, as well as variability of connection arrangements, while maintaining the required level of reliability and safety, is regarded today as an urgent task for the energy industry as a whole. The article is devoted to the problem of determining the efficiency of the circuit design solution for a double-circuit three-phase power transmission line with an additional mode of operation — «with a split back-up phase» and determining its main reliability indicators. A circuit design solution for a double-circuit power transmission line with expansion of operating modes is presented in detail. The functional redundancy of the transmission line in accordance with the circuit design solution is based on switching of a conventional double-circuit power transmission line in the emergency mode to the single-circuit split-phase mode, which is the second working circuit. The ways of increasing the natural power of a double-circuit power transmission line are considered. The results of calculation of the capacity of a line with a split back-up phase and a comparison of the main parameters of overhead transmission lines with an additional mode of operation — with a split back-up phase — and power lines in conventional modes of operation, are presented. The results of calculations of reliability indicators are presented, such as the probable relative number of hours of interruption of power supply and the undersupply of electrical energy. A comparison of options have shown that the probable relative under-supply of the electric power of a double-circuit overhead transmission line with an additional operating mode — with a split back-up phase, is lower by approximately 13% than that of a conventional double-circuit power line, which will positively affect the maneuverability and reliability of the entire system.

Selection of an optimal electric monorail loading technique in underground mining using analytic hierarchy process and Yager's technique

The electric monorail transport system has found wide application in decline development. However, the loading mechanism in this haulage system still possesses a great challenge to its overall optimal efficiency. It has been demonstrated that high loading time is the main pitfall to high advance rates in monorail application. In this paper, the analytic hierarchy process and Yager's multiple criteria decision making techniques were used to select the optimal loading mechanism in the electric monorail transport system among three loading alternatives, namely, electric loader, conventional load-haul-dump unit and pneumatic loading system. Results of the two methods show that the electric loading technique is the optimal monorail loading system for efficient decline development in narrow vein deposits. Additionally, sensitivity analyses under the two techniques show that the electric loader system is always selected as the optimal solution to ±40% changes in the weight of criteria. It was also deduced that the solution under both methods is most sensitive to changes in the weight of the loading rate criterion.

Non-isolated load sharing direct current system operation with use of the auctioneering diodes

The paper presents the background and results of numerical simulation and experimental research of a system using auctioneering diodes used to distribute the electrical power between two power converters connected with intermediate circuits in parallel, direct connection. Presented non-isolated power distribution system which utilizes blocking diodes placed in DC branches are used in the selected ship's electrical systems, however, they create problems related to control and handling ground faults. Another issue occurring during the operation of this type of systems is increased heat dissipation while diodes switching. Selected problems related to the operation of experimental system have been identified by means of simulation studies and experiments carried out in a 11 kVA laboratory system and the theoretical basis along with results are provided in the article.

Контроль сопротивления изоляции судовых электроэнергетических систем с применением теории массового обслуживания

Контроль сопротивления изоляции судовых электроэнергетических систем с применением теории массового обслуживания

Environmental benefits of modern power system and clean energy

Nowadays, the world is at a critical moment of facing serious environmental and economic problems. A very large number of people in developing countries is exposed to dangers associated with flammability and toxicity of traditional source of energy while others in industrialized countries are facing the effects of atmospheric air pollution and green house (GHG) gas emission .Despite the global reforestation policies, despite latest remarkable increase in renewable energy and natural gas production, there is still a problem of domination fuel and coal consumption. This paper explored the effects of rapid economic growth, industrial development on climate. Additionally the effects of continuous exponential population growth, a fast increase of energy global energy demand, conventional transport system on carbon and GHG emission have discussed. Finally the paper revealed how modern smart electricity system with sustainable energy system and electric transport system contribute to the reduction of hazardous emission.

Fryze reactive power of trams in effective stochastic recuperation processes

Urban electric transport system, particularly tram systems, is not a direct current system not only in traction mode but in regenerative modes as both voltage on a collector and regenerative current are stochastic abruptly variable processes. The above- mentioned facts determine availability of Fryze’s reactive power in this system that flows from a railway substation to trams, leads to incidental losses of energy and significantly reduces its quality. So evaluation of power effectiveness of the system in electrical trams operation is impossible without determining the level of reactive power in this system. We have analytical expression of reactive power by Fryze. Numerical calculations for trams type T3D and T4D in regenerative braking modes are done. Probabilistic statistical data processing operation of reactive power expressions is done. It is determined that reactive power changes in the limit of 10…100 kilo-volt ampere reactive with mathematical expectation – 37,0 kilo-volt ampere reactive. Statistical allocation of random power values are different. Numerical calculations of incidental losses, energy of recuperation are done and they range supplementary – 20% from total losses. It is stated that coefficient of reactive power of system route of trams is exceeding permissible value 0,25.

Research of reliability of urban electric transport system

Modern methods for analyzing and assessing the reliability of complex technical systems consider only its individual elements. The specifics of structural-functional interactions and integration into subsystems of different hierarchical levels are not taken into account. Studies show that analyzing the reliability of urban electric transport, also focus on individual components: the reliability of electric traction rolling stock, the reliability of the power supply system, the reliability of the track infrastructure, etc. The authors propose an approach that allows to consider urban electric transport as a complex technical system consisting of several levels that are hierarchically subordinate. Each level combines the components directly involved in the transmission and transformation of electric power into mechanical operation of the rolling stock under the influence of the external environment by means of traction electrical equipment. This approach will allow to develop the theoretical foundations of methods for analyzing the impact of the reliability of individual components of a complex technical system of urban electric transport on the effectiveness of the electric traction implementation.