Urban Electric Network Research Articles

Measuring the effectiveness of incorporating mobile charging services into urban electric vehicle charging network: An agent-based approach

Mobile charging service (MCS) has emerged as a cost-efficient solution to compensate for the limitations of fixed charging stations (FCSs) in service capacity and coverage. Nevertheless, the impacts of incorporating the MCS into the charging infrastructure network have not been well understood. Therefore, this study introduces an exhaustive framework for devising Agent-based Modeling (ABM) to delineate electric vehicle (EV) drivers' daily travels and charging behaviors within the integrated charging network. Specifically, the developed ABM framework encompasses both internal attributes of individuals and external variables of charging and transport networks that potentially shape EV drivers’ public charging decisions. It generates authentic daily charging demands for FCSs and MCSs and provides a streamlined process to further incorporate more charging modes into the EV charging ecosystem. Subsequently, we opted for the Salt Lake City metropolitan area to implement our framework and showcase the effectiveness of MCS integration on the charging network over various EV adoption levels and network settings. The findings of the designed case study unravel the choice patterns of EV drivers when facing diverse charging options and pinpoint the strengths and weaknesses of MCS incorporating into the urban charging network at different stages.

Optimizing quasi-dynamic wireless charging for urban electric buses: A two-scenario mathematical framework with grid and PV-battery systems

This paper presents a mathematical optimization framework for the strategic placement of quasi-dynamic wireless charging (QWC) stations within road networks to address the charging needs of battery electric buses (BEBs). This study evaluates two scenarios for powering the buses. In the first scenario, a grid-connected system is considered. The optimization aims to minimize annual costs related to capital, operation, and energy losses of the electric bus fleet. This involves determining the optimal locations for QWC stations, the length of power transmitters, and the corresponding battery capacities for the BEBs. Using MATLAB-based optimization tools Casadi and Yalmip, with solvers Bonmin and Fmincon, the optimal configuration includes a 13 kWh battery capacity and a 300 m power transmitter distributed across five bus stop areas. The second scenario employs a chance-constrained optimization approach for an isolated solar photovoltaic (PV) and battery energy storage system (BESS). This system is designed to reliably meet the BEBs' energy requirements throughout the day, considering different seasonal data (winter, summer, all seasons/year-round). The optimization results for the PV and BESS capacities vary with the seasons: 394.247 kW and 2012.6 kWh using summer data, 1762.1 kW and 2738.2 kWh using winter data, and 1610.8 kW and 2741.9 kWh using year-round data. Additionally, the paper examines the impact of varying bus fleet sizes on the optimal battery size and power transmitter combination using a real-world example of the bus route between Khalifa City and Abu Dhabi Downtown in the UAE. The findings suggest that larger batteries with fewer or no charging stations are more economical for smaller fleets. Conversely, as the fleet size increases, a combination of smaller battery sizes and a greater number (and length) of QWC (power transmitters) becomes more cost-effective. This research offers significant insights into the efficient deployment of QWC stations and the integration of renewable energy and energy storage for sustainable urban electric bus networks. The proposed optimization models provide a systematic approach to designing and operating charging infrastructure, contributing to sustainable urban transportation systems. Moreover, the study highlights the influence of seasonal data on PV system sizing and costs.

Повышение надежности электроснабжения постов электрической централизации Восточного полигона

Signalling control posts are one of the most responsible consumers of electricity on railway transport. In some sections of the Eastern operating domain power supply is organized from urban electric networks, where in recent years, due to increasing loads and certain deterioration of networks, there has been an increasing tendency for damage at signalling control posts. The article presents a model of the power supply system for the signalling control posts of the Eastern operating domain, developed in the Fazonord programming and computing suite. In the process of modeling, the optimal option for power supply from railway sources was selected, which provides a sufficient level of reliability and reduces operating costs.

ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ РОЗПОДІЛЬНИХ МЕРЕЖ РАЙОНІВ МАЛОПОВЕРХОВОЇ ЗАБУДОВИ МІСТ

The article analyzes the methods of estimating the parameters and regimes of electrical distribution networks in areas of low-rise urban development. A method for optimizing the parameters of distribution networks of 0.38 kV under conditions of uncertainty of the initial information is proposed. It is shown that one of the unsolved problems of calculating the parameters of distribution electric networks of cities is the determination of the estimated load of utility consumers. Its dependence on the characteristics of consumers and their number connected to the lines of city transformer substations causes the low accuracy of calculations. In this case, the error of calculating the transformer substations load can reach 10-25%, and the error of calculating the cross-sections of 0.38 kV lines reaches 40%. In the assumption of the constancy of the total length of the lines of urban electric networks and the invariance of the distance between loads, calculation formulas for linear moments and load distribution coefficients are proposed, and based on them, models of intersection and power losses in lines are developed. Taking into account the developed models, we offer discounted cost models for 0.38 kV networks and transformer substations when calculating economic current density and allowable voltage costs. Keywords: optimization, distribution networks, uncertainty, efficiency, low-rise building, scheme.

On the question of optimizing the quality of energy in city electric network

As is well known, ensuring the energy quality indicators set by the State Technical Service of Ukraine in electrical networks is an extremely important task. The heterogeneity of load schedules of consumers of urban electric networks in combination with the variety of their operating modes, phase differences, non-linearity and high speed of parameter changes led to the fact that asymmetry, non-sinusoidal, voltage deviations and fluctuations in the networks became permanent factors that significantly reduce the quality of the networks and consumers connected to them. In addition, studies of the power factor in urban electrical networks indicate a low level of reactive power compensation in them. This is due to the high value of voltage and power losses in networks, the technical need and economic feasibility of compensation of reactive power in them. Research conducted at O. M. Beketov Kharkiv National University of Urban Economy, testify to the fact that the main strategic directions for improving the quality of energy in urban electric networks are voltage regulation, taking into account the comprehensive solution of the issues of improving the quality of energy and compensation of reactive power. At the same time, the technical solution to the problem is on the way of multi-level correction of quality indicators by using additional multifunctional devices, the most important place among which is occupied by devices made on the basis of thyristor-controlled voltage transformers. The paper presents the results of this study. It is also determined that in combination with the automation of the process of managing multifunctional devices, the use of multifunctional converters as a whole allows solving the issue of optimizing the operation modes of city power supply systems. The application of research results in general allows solving the issue of energy quality optimization in urban electrical networks.

A simple method for sizing and estimating the performance of PV systems in trolleybus grids

Solar PV systems have so far been the source of choice for the sustainable supply of urban electric transport networks—like trams and trolleybus grids. However, no consensus exists yet on the placement or sizing of PV systems at the traction substations, and no method is available for easy estimation of the PV system utilization performance. The latter is crucial for understanding the need for storage, grid exchange, or even power curtailment, and has therefore a direct impact on the technical and financial feasibility of the project.This paper looks at 11 Key Performance Indicators (KPI) that are available to trolleybus operators, in two PV case studies on Arnhem (NL) and Gdynia (PL), using verified and validated bus, grid, and PV models. Through one KPI, namely the here-defined Energy Traffic KPI, a strong trend (R2=0.93) is described that can now allow stakeholders a quick estimation of the PV potential using a simple third-degree polynomial instead of resorting to the complex grid, bus, and PV modelling. A simple placement and sizing method is also presented derived from this KPI, in a way as to increase the technical and economical feasibility of an installed PV system. Despite all efforts, stakeholders are still warned of an intrinsic, upper-performance plateau that exists in transport grids, at around 38% direct PV utilization, caused by the unavoidable mismatch between PV generation and vehicle timetables and schedules. Stakeholders are urged to implement more smart grid loads as a base load to increase the feasibility of their investments in renewables, and to transform the transportation systems thereby to multi-functional grids that can assist the main city grid.

Evaluation of the Operating Modes of the Urban Electric Networks in Dushanbe City, Tajikistan

Currently, energy saving has become an acute problem all over the world. Due to the rapid development of both the energy and information technology sectors, as well as an increase in the electricity demand, the electric distribution system is facing problems caused by stricter requirements for electricity quality, reliability, efficiency, and sustainability. Therefore, the use of energy-saving technologies, both the improvement of existing ones and the application of new ones, is one of the main reserves for electricity saving in power supply systems. This study is devoted to the evaluation of the operating modes of transformer substations of the 6–10 kV electric distribution network in Dushanbe city, based on the results of control winter measurements and the dependence of the low coefficient of active power in transformer substations. It has been observed that, with a low coefficient of active power in transformer substations, when transmitting electricity from substation busbars to transformer substations of a final consumer via overhead transmission lines (an average length of 5 km), the voltage loss exceeds the maximum permissible values. When transmitting electricity via cable lines, the voltage losses are within the limit of 5%. However, a low active power factor may be the reason for an increase in capacitive currents, followed by the command of single-phase earth fault currents. Due to the low active power factor, the increase in voltage losses and useful power losses leads to the inefficient operating modes of the transformer substations.

Алгоритм обучения искусственной нейронной сети для факторного прогнозирования электропотребления бытового сектора

An analysis of the known methods for forecasting electricity consumption in urban distribution electric networks has shown that they are all based on the availability of sources of both electric and thermal energy. Reduction or complete absence of heat sources leads to significant forecast errors, which entails a drop in the energy efficiency of urban electrical networks and degraded reliability of power supply system individual components. Theoretical, computer, and neural network models that help achieve more accurate forecasting of electricity consumption in the household sector are proposed. Based on the developed mathematical model and taking into account the factor coefficients obtained for 2020 for nine cities of the Republic of Tajikistan, monthly values of the coefficient characterizing the terrain conditions were calculated. The results obtained using the proposed mathematical model were compared with the data of computer and neural network models. A method that helps obtain more accurate forecasting of electricity consumption in the household sector is proposed. To automate the monitoring and control of electricity generated by renewable energy sources, an algorithm for training an artificial neural network for factor-based forecasting of electricity consumption is proposed, the use of which will help improve the forecasting accuracy owing to the possibility of constantly training the neural network. The algorithm efficiency is confirmed by good agreement between the results obtained both using the proposed models and based on the readings of electricity meters.

Троллейбусы с возможностью автономного хода и их влияние на проектирование маршрутной сети городского пассажирского транспорта

The article discusses the main causes of degradation of trolleybus systems in Russian cities in the last 30 years. The main advantages of new trolleybuses with the possibility of autonomous running are given and the main options for the development of the urban electric transport network through the use of rolling stock of this type are proposed.

МОДЕЛИРОВАНИЕ ПЕРЕХОДНОГО ПРОЦЕССА В РАСПРЕДЕЛИТЕЛЬНОЙ СЕТИ 10 КВ ПРИ ОДНОФАЗНОМ ЗАМЫКАНИИ НА ЗЕМЛЮ

Relevance At the moment, finding single-phase earth faults in networks with isolated and compensated neutral is still a problem with ambiguous solutions. Existing earth fault protection devices are relevant only in special cases. In networks with a large number of outgoing connections and an extensive circuit, these protections are not able to provide absolutely selective triggering. Therefore, this problem is especially relevant for urban electric networks, since these networks are characterized by both the mass of lines and the heterogeneous nature of the load. Also, the difficulty in detecting damage is the secrecy of the transmission lines, since in these networks they are mainly made by cables. To unambiguously determine the earth fault, in urban distribution networks, earth fault protection is most often used in conjunction with the sequential shutdown method. The use of this method greatly facilitates the determination of an earth fault, but at the same time it is destructive in relation to the power supply of consumers. Since urban distribution networks supply densely populated areas with electric energy, this disadvantage further exacerbates the existing problem. In order to limit these negative consequences, it is possible to make switches by regrouping the network into sections. Such switching will allow you to quickly identify a damaged line and eliminate short-term disconnections of consumers during the search for a ground fault. However, the application of this method is accompanied by switching in the distribution network during a single-phase earth fault. Therefore, it is necessary to study the transient process that occurs during such switching in 10 kV distribution networks in order to verify the applicability of such switching. Also, this study will set the vector for further scientific research in this area. Aim of research Simulation of the transient process that occurs when combining 10 kV networks for parallel operation during a single-phase earth fault. Research methods The methodological basis in this article is mathematical simulation modeling. Results Overvoltages arising during switching in a 10 kV network during a ground fault are considered. Their analysis and the conditions of applicability of the switches performed when determining the earth fault in distribution cable networks are carried out.

Analysis of existing types of protection against single-phase earth faults and their application conditions

Currently, the problem of determining a single-phase earth fault in networks with isolated and compensated neutral mode is still relevant. According to the existing data, according to the time of elimination of these technological violations, the conclusion arises, according to which the effectiveness of existing protections is called into question. This issue is particularly acute for electric grid companies that serve urban electric networks, since the mass of lines laid next to each other and the heterogeneous nature of the load makes the network mode not suitable for the use of modern protections. Therefore, as a definition of damage, the method of sequential disconnection and the method of dividing the network into sections, which were used half a century ago, are used. Therefore, the analysis of the existing earth fault protection will help to identify the existing problem more clearly, as well as set the direction for further scientific research in this area. The methodological basis, in this article, is the analysis. The information for this method is taken from the theoretical and empirical information of previously published works. In particular, the existing types of protection against single-phase earth faults are considered. Their analysis and conditions of applicability for the electric economy of urban electric networks are made. In the course of the analysis, it was found that the existing protection against single-phase earth faults can reduce the search range of OZZ, but, so far, they can not provide absolute selectivity for the conditions of urban electrical networks made by cable lines. Since such electrical networks are typical for densely populated areas, the above problem is relevant and requires a quick solution.

Research on Urban Electric Vehicle Public Charging Network Based on 5G and Big Data

Under the pressure of energy and environmental protection, we will promote the technological progress and demonstration of electric vehicles, and the construction of charging facilities will continue. Charging facilities planning and orderly charging, as two major research directions of electric vehicle infrastructure, are of great significance for the future development of electric vehicles. The optimal charging of electric vehicles can effectively improve the safe and economic operation ability of distribution network, which is of great significance to its safe operation. Therefore, this paper proposes the outsourcing test experiment and processing of urban electric vehicle public charging network based on 5G and big data. In this paper, through the analysis of the development status of urban electric vehicles, this paper proposes to optimize the charging mode of electric vehicles by combining the charging network forward and backward algorithm. In the outsourcing test experiment, the electrical safety test shows that when the current reaches 1.1-37.1kw: 5000A, when the power factor is 0.8 ∼ 0.9, when the short-circuit current impact is tolerated, the connection device will not affect the breaking operation by contact fusion welding, and the insulation protection will not be invalid. Through investigation and analysis, the satisfaction degree of electric vehicle optimization algorithm is increasing year by year. Through the analysis of the test results, the research in this paper has achieved ideal results and made a contribution to the research of urban electric vehicle public charging network.

On the choosing the installation location the balancing devices in low-voltage distribution electric networks

The experimental studies result on the power quality and additional power losses analysis caused by the asymmetric modes occurrence in three-phase four-wire 0.38 kV electrical networks are considered. The operating modes 38 kV networks several types simulation – with power take-off nodes distributed along the power line, and an electric network with a concentrated load is carried out. The programs have been developed that allow to assess the change in indicators characterizing asymmetric modes, as well as programs that allow us to visualize this process change. The most installing special symmetrical devices appropriate places in electric networks with a distributed load (rural electric distribution networks) and concentrated power take-off nodes electric networks (urban electric networks) have been identified to minimize losses and improve the power quality. A numerical studied indicators analysis was performed.

Modelling the Operating Mode of the Urban Electrical Network and Developing a Method for Managing These Modes

The article examines the influence of variable factors on the operating mode of the urban electrical network (the presence of other energy sources, house designs, climatic and meteorological factors, the welfare of the population). The coefficient of accounting for variable factors is derived. To assess the impact on the network operating mode, a computer model was built, the use of which made it possible to develop a method, and on its basis, a device that allows you to control the network operating mode.

Enhancing reliability of electricity supply of city electric networks cities of Dushanbe

The article is devoted to the actual problem of how to improve the reliability of the urban electric network. Based on the statistical analysis of the breakdown of electrical equipment in urban distribution networks in Dushanbe for the periods of 2017-2018 and for the reasons of damage leading to these emergency outages, the factors that affect the distribution of damage leading to emergency outages are identified. Taking into account the identified factors, a power consumption forecasting system is proposed that takes into account the local conditions of the city of Dushanbe. it allows us to suggest a way to control the operating parameters of the electric network, thereby increasing the reliability of the city's electric network in Dushanbe based on the recommendation of power consumption standards. Implementation of the control of the proposed method for improving the reliability of power supply to the urban electric network is proposed on the basis of the functionality of modern smart electricity metering using the control algorithm. To implement the control algorithm, schematic design for receiving and transmitting information from smart power metering to the data collection centre is proposed.

Research and Analysis on the Use of 5G and Big Data in Urban Electric Vehicle Public Charging Networks

In recent years, the electric vehicle sales market has been expanding, but the existing urban electric vehicle public charging network system is not optimistic. Most of the researches on the construction of charging facilities and charging network are still at the stage of qualitative analysis. This paper uses the method of questionnaire survey to investigate the current situation of electric vehicle public charging network system in China. Using 5g new technology and big data technology for research and analysis, from the city level, we can explore whether the establishment of electric vehicle public charging network is feasible. The big data analysis technology can not only promote the efficiency construction of charging pile network, but also improve the user experience of charging pile charging station. At the same time, it also increases the application scenarios of charging pile network, which is not only of great significance to the development of the entire electric vehicle industry, but also greatly promotes the rapid development of the city.

Optimal energy management of a DC power traction system in an urban electric railway network with dogleg method

ABSTRACT Today, due to the several benefits of using the subway as a clean transportation system and also its expansion in many cities around the world, electrification to urban and suburban railway systems is experiencing a very important development procedure. Optimal power supply and management of energy that is economically viable is one of the important issues in the design of such systems. In this paper, in order to provide an optimal energy management and to determine the location of rectifier substations (RSs), and also to calculate power supply capacity (PSC) of the traction units, an optimal design and simulation of a DC railway traction power supply system (RTPSS) in urban area is proposed. In this regard, first, the structure of power system of RSs used in urban area is presented and analyzed in detail. Then, considering the importance of the standard criteria in designing the dynamics of a city’s RTPSS, an equivalent circuit for the desired network is provided. After defining the governing equations of the network and using the dogleg optimization method, to ensure convergence, the speed of solving equations is improved. In this study, in order to verify the performance of the presented method, the cost-based convergence characteristic curve for Dogleg optimization method is compared to the particle swarm optimization (PSO) approach. In order to confirm the robustness, applicability, and superiority of the proposed approach for optimal design and energy management in a city railway power system, the presented method is applied to a real study case. The obtained results through the simulation approve the effectiveness of using the Dogleg optimization method in power consumption by approximately 255 kWh in reducing energy compared to the practical energy consumption for one train during the trip in normal condition.

Оценка погрешности расчета нагрузочных потерь электроэнергии в распределительных электрических сетях напряжением 6—10 кВ

The aim of the study is to estimate the level of load losses for actual (nonuniform) loading of transformer substations in comparison with the load loss level under the conditions of their being uniformly loaded for a typical 6 kV urban distribution electric network. The extent to which such networks are equipped with automated information and measurement systems for fiscal electricity metering is extremely poor. Therefore, not only the load curves of the 6--10/0.4 kV substation transformers, but also their load factors are unknown in the majority of cases. Under these conditions, in calculating the load losses in 6--10 kV distribution electric networks, it is assumed that all substation transformers are uniformly (equally) loaded. The load losses in these electrical networks are calculated with a certain error associated with the assumption according to which the substation transformers are supposed to be uniformly loaded. Under these conditions, estimation of this error becomes of issue. The article describes the modeling, calculation and analysis of technical losses of electricity under the conditions of nonuniformly loaded transformers of a typical urban distribution network consisting of four transformers and four cables interconnecting them. The modeling and calculation of power losses were carried out using the RAP-10-st computer program for several different groups of transformer loading factors. Within each group, different subgroups were produced by rearranging the group loading factors. Each subgroup modeled a nonuniform transformers loading mode in the studied network. For each of these modes, the power losses were calculated and studied with the use of the RAP-10-st computer program. A conclusion has been drawn from the obtained analysis results regarding the error in determining the load losses associated with the assumption about the uniform loading of the substation transformers in the network. The obtained results may prompt electric grid companies to increase the extent of fitting their networks with automated information and measurement systems for fiscal electricity metering to improve the accuracy of determining the load losses.

Analysis of leakage currents in modern urban electric networks

Analysis of leakage currents in modern urban electric networks

Power Line Communication Applied in a Typical Brazilian Urban Power Network

Smart Grids are composed of many features and new technologies which are gradually incorporated to traditional electrical networks. Smart Metering is one of these new features, it remotely manages consumers, enables fraud prevention, identifies faults and shutdowns, and manages distribution transformers, among others. In this context, this paper presents the development of a complete Smart Metering System which utilizes Power Line Communication (PLC) technology considering the standard PRIME (PoweRline Intelligent Metering Evolution) applied in a typical Brazilian urban electrical network. The results analysis shows that the standard PRIME, although quite widespread in the European community, presents several operational constraints in the Brazilian electrical network affecting its performance in terms of communication, but not preventing its use. Therefore, it is urgent to apply new technical standards and that inspection agencies work to ensure that such standards will be applied, under the penalty of making unfeasible the use of the new communication technologies for the environment of the Smart Grids in the Brazilian scenario.