1) The document discusses electrical safety considerations for large-scale electric vehicle charging stations (EVCSs). It proposes a holistic risk assessment approach to evaluate the electrical safety of EVCSs that are coupled with renewable power generation.
2) Key safety topics examined include facility degradation over time, cybersecurity challenges from increased communication and smart charging, and potential mismatches between renewable output and EVCS demand that could impact system stability.
3) The proposed risk assessment framework is intended to provide guidelines for EVCS operators to continuously monitor operations and effectively manage electrical safety.
Unification Requirements of Electric Vehicle Charging InfrastructureIAES-IJPEDS
By increasingelectric vehicles in numbers and getting the public attention,
availability, safety and accessibility of its charging infrastructure are key
factorsto users’ satisfaction. Charging infrastructure in electric vehicle
industry can have a role as an interface for exchanging information among
other components as well. Currently, lack of universality in electric vehicle
industry has caused anisolation in networks of electric vehicles. This
isolationwill cause difficulty in having an aggregated set of information
about electric vehicles and their consumption pattern. The paper reviews
current charging infrastructure and the possibility of providing universality
based on candidate protocols and technologies.
Review of Wireless Charging Technologies for Electric VehiclesIRJET Journal
This document provides a review of wireless charging technologies for electric vehicles. It discusses how wireless charging could help boost adoption of electric vehicles by providing a more convenient charging option compared to plug-in cables. Both static wireless charging systems, where the vehicle is parked, and dynamic wireless charging systems, which could charge vehicles while driving, are examined. The document outlines the basic operating principles of wireless charging systems and reviews some of the health and safety concerns, such as electrical, magnetic, and fire hazards. It also discusses the relevant international standards and regulations regarding wireless charging systems.
IRJET- Wireless Charging of Electric VehiclesIRJET Journal
This document summarizes research on wireless charging of electric vehicles. It discusses both stationary and dynamic wireless charging systems. For stationary systems, charging pads are installed in parking lots, garages, etc. and electric vehicles charge when parked over the pad. Dynamic wireless charging allows electric vehicles to charge while in motion by transmitting power through roadway coils to vehicle coils. Challenges include coil alignment, power transfer efficiency, and safety regulations. The document outlines applications of both static and dynamic wireless charging systems to promote electric vehicle use and reduce fuel consumption and emissions.
The security of Electric Vehicle (EV) charging has gained momentum after the increase in the EV adoption
in the past few years. Mobile applications have been integrated into EV charging systems that mainly use a
cloud-based platform to host their services and data. Like many complex systems, cloud systems are
susceptible to cyberattacks if proper measures are not taken by the organization to secure them. In this
paper, we explore the security of key components in the EV charging infrastructure, including the mobile
application and its cloud service. We conducted an experiment that initiated a Man in the Middle attack
between an EV app and its cloud services. Our results showed that it is possible to launch attacks against
the connected infrastructure by taking advantage of vulnerabilities that may have substantial economic and
operational ramifications on the EV charging ecosystem. We conclude by providing mitigation suggestions
and future research directions.
A Comprehensive Review of Electric Vehicle Charging Station TopologiesIRJET Journal
This document provides a comprehensive review of electric vehicle charging station topologies. It discusses several fast charging station designs that incorporate solar photovoltaics and battery energy storage to provide renewable power. These include fast charging stations with solar PV integration and predictive controllers, PV-assisted fast charging stations, and multiport converter-based charging stations that connect multiple power sources including solar, batteries, and the electric grid. The document also examines different electric vehicle charging standards and scenarios, including uncontrolled home charging and various controlled charging approaches to encourage off-peak use.
The document discusses cyber-physical systems (CPS) in the context of wind energy and the Internet of Energy (IoE). It describes how CPS can enable wind energy systems to interface with the IoE through embedded intelligence, sensors, and communication networks. This would allow for increased efficiency, cost savings, and reduced energy waste through applications like smart grid integration, distributed control of generation systems, and automated maintenance processes. The document outlines the physical and cyber layers of wind energy conversion systems (WECS) and discusses modeling, safety, security, and sustainability considerations for developing CPS-enabled next-generation WECS.
A Comprehensive Overview of Electric Vehicle Charging using Renewable EnergyIAES-IJPEDS
The integration of PV with the electric vehicle (EV) charging system has been on the rise due to several factors, namely continuous reduction in the price of PV modules, rapid growth in EV and concern over the effects of greenhouse gases. Over the years, numerous papers have been published on EV charging using the standard utility (grid) electrical supply; however, there seems to be an absence of a comprehensive overview using PV as one of the components for the charger. With the growing interest in this topic, it is timely to review, summarize and update all the related works on PV charging, and to present it as a single reference. For the benefit of a wider audience, the paper also includes the bries description on EV charging stations, background of EV, as well as a brief description of PV systems. Some of the main features of battery management system (BMS) for EV battery are also presented. It is envisaged that the information gathered in this paper will be a valuable one–stop source of information for researchers working in this topic.
Enhancing battery system identification: nonlinear autoregressive modeling fo...IJECEIAES
Precisely characterizing Li-ion batteries is essential for optimizing their
performance, enhancing safety, and prolonging their lifespan across various
applications, such as electric vehicles and renewable energy systems. This
article introduces an innovative nonlinear methodology for system
identification of a Li-ion battery, employing a nonlinear autoregressive with
exogenous inputs (NARX) model. The proposed approach integrates the
benefits of nonlinear modeling with the adaptability of the NARX structure,
facilitating a more comprehensive representation of the intricate
electrochemical processes within the battery. Experimental data collected
from a Li-ion battery operating under diverse scenarios are employed to
validate the effectiveness of the proposed methodology. The identified
NARX model exhibits superior accuracy in predicting the battery's behavior
compared to traditional linear models. This study underscores the
importance of accounting for nonlinearities in battery modeling, providing
insights into the intricate relationships between state-of-charge, voltage, and
current under dynamic conditions.
Unification Requirements of Electric Vehicle Charging InfrastructureIAES-IJPEDS
By increasingelectric vehicles in numbers and getting the public attention,
availability, safety and accessibility of its charging infrastructure are key
factorsto users’ satisfaction. Charging infrastructure in electric vehicle
industry can have a role as an interface for exchanging information among
other components as well. Currently, lack of universality in electric vehicle
industry has caused anisolation in networks of electric vehicles. This
isolationwill cause difficulty in having an aggregated set of information
about electric vehicles and their consumption pattern. The paper reviews
current charging infrastructure and the possibility of providing universality
based on candidate protocols and technologies.
Review of Wireless Charging Technologies for Electric VehiclesIRJET Journal
This document provides a review of wireless charging technologies for electric vehicles. It discusses how wireless charging could help boost adoption of electric vehicles by providing a more convenient charging option compared to plug-in cables. Both static wireless charging systems, where the vehicle is parked, and dynamic wireless charging systems, which could charge vehicles while driving, are examined. The document outlines the basic operating principles of wireless charging systems and reviews some of the health and safety concerns, such as electrical, magnetic, and fire hazards. It also discusses the relevant international standards and regulations regarding wireless charging systems.
IRJET- Wireless Charging of Electric VehiclesIRJET Journal
This document summarizes research on wireless charging of electric vehicles. It discusses both stationary and dynamic wireless charging systems. For stationary systems, charging pads are installed in parking lots, garages, etc. and electric vehicles charge when parked over the pad. Dynamic wireless charging allows electric vehicles to charge while in motion by transmitting power through roadway coils to vehicle coils. Challenges include coil alignment, power transfer efficiency, and safety regulations. The document outlines applications of both static and dynamic wireless charging systems to promote electric vehicle use and reduce fuel consumption and emissions.
The security of Electric Vehicle (EV) charging has gained momentum after the increase in the EV adoption
in the past few years. Mobile applications have been integrated into EV charging systems that mainly use a
cloud-based platform to host their services and data. Like many complex systems, cloud systems are
susceptible to cyberattacks if proper measures are not taken by the organization to secure them. In this
paper, we explore the security of key components in the EV charging infrastructure, including the mobile
application and its cloud service. We conducted an experiment that initiated a Man in the Middle attack
between an EV app and its cloud services. Our results showed that it is possible to launch attacks against
the connected infrastructure by taking advantage of vulnerabilities that may have substantial economic and
operational ramifications on the EV charging ecosystem. We conclude by providing mitigation suggestions
and future research directions.
A Comprehensive Review of Electric Vehicle Charging Station TopologiesIRJET Journal
This document provides a comprehensive review of electric vehicle charging station topologies. It discusses several fast charging station designs that incorporate solar photovoltaics and battery energy storage to provide renewable power. These include fast charging stations with solar PV integration and predictive controllers, PV-assisted fast charging stations, and multiport converter-based charging stations that connect multiple power sources including solar, batteries, and the electric grid. The document also examines different electric vehicle charging standards and scenarios, including uncontrolled home charging and various controlled charging approaches to encourage off-peak use.
The document discusses cyber-physical systems (CPS) in the context of wind energy and the Internet of Energy (IoE). It describes how CPS can enable wind energy systems to interface with the IoE through embedded intelligence, sensors, and communication networks. This would allow for increased efficiency, cost savings, and reduced energy waste through applications like smart grid integration, distributed control of generation systems, and automated maintenance processes. The document outlines the physical and cyber layers of wind energy conversion systems (WECS) and discusses modeling, safety, security, and sustainability considerations for developing CPS-enabled next-generation WECS.
A Comprehensive Overview of Electric Vehicle Charging using Renewable EnergyIAES-IJPEDS
The integration of PV with the electric vehicle (EV) charging system has been on the rise due to several factors, namely continuous reduction in the price of PV modules, rapid growth in EV and concern over the effects of greenhouse gases. Over the years, numerous papers have been published on EV charging using the standard utility (grid) electrical supply; however, there seems to be an absence of a comprehensive overview using PV as one of the components for the charger. With the growing interest in this topic, it is timely to review, summarize and update all the related works on PV charging, and to present it as a single reference. For the benefit of a wider audience, the paper also includes the bries description on EV charging stations, background of EV, as well as a brief description of PV systems. Some of the main features of battery management system (BMS) for EV battery are also presented. It is envisaged that the information gathered in this paper will be a valuable one–stop source of information for researchers working in this topic.
Enhancing battery system identification: nonlinear autoregressive modeling fo...IJECEIAES
Precisely characterizing Li-ion batteries is essential for optimizing their
performance, enhancing safety, and prolonging their lifespan across various
applications, such as electric vehicles and renewable energy systems. This
article introduces an innovative nonlinear methodology for system
identification of a Li-ion battery, employing a nonlinear autoregressive with
exogenous inputs (NARX) model. The proposed approach integrates the
benefits of nonlinear modeling with the adaptability of the NARX structure,
facilitating a more comprehensive representation of the intricate
electrochemical processes within the battery. Experimental data collected
from a Li-ion battery operating under diverse scenarios are employed to
validate the effectiveness of the proposed methodology. The identified
NARX model exhibits superior accuracy in predicting the battery's behavior
compared to traditional linear models. This study underscores the
importance of accounting for nonlinearities in battery modeling, providing
insights into the intricate relationships between state-of-charge, voltage, and
current under dynamic conditions.
Adverse effects of fossil fuel burning and internal combustion engine vehicles have alarmed nations worldwide. Governments are taking steps to promote the use of Electric Vehicles due to less carbon emissions and to pacify the environmental issues. The added load of Electric Vehicles poses a threat to the existing grid which leads to instability of the grid. The problem of demand supply mismatching can be solved by integrating the renewable energy sources with Electric vehicle charging station resulting in bi-directional flow of power. Vehicle to Grid technology helps the utility with active and reactive power support by feeding power from battery pack to grid and vice versa. Vehicle to Grid describes a system in which electric vehicles, plug-in hybrid, fuel cells electric vehicles are connected to the power grid to provide high power, spinning reserves, regulation services etc. The perspective of this study is to evolve a smart charging schedule based on the load on grid, time of use of the EV and other factors in order to minimize cost of charging for electric utilities and EVs as well as promote profits to EV owners.
This document discusses developing an information model to connect electric vehicle supply equipment (EVSEs) to customer energy management systems (CEMS) through the Energy Information Standards Alliance. The model would allow two-way communication between EVSEs and CEMS to facilitate demand response and other grid services. Integrating EVSEs with CEMS could help manage electric vehicle charging load and make use of stored vehicle energy for applications like peak shaving and renewable energy firming.
Electric vehicle (EV) charging station powered by the scattered energy sources with DC Nanogrid (NG) provides an option for uninterrupted charging. The NG powered by the renewable energy sources (RES) of photovoltaic (PV) and wind energy. When the excess power produced by the renewable energy stored in the local energy storage unit (ESU) utilized during shortage power from the renewable sources. During the overloading of NG and demand of energy in ESU; the mobile charging station (MCS) provides an uninterrupted charging. The MCS provides an option for battery swapping and vehicle to grid feasibility. The MCS required to monitor the state of charge (SOC) and state of health (SOH) of the battery. Monitoring of SOC and SOH related to the various battery parameters like voltage, current and temperature. A laboratory prototype is developed and tested the practical possibility of EV to NG and Internet of things (IoT) based monitoring of battery parameters.
This document presents a proposed eco-friendly charging station project that uses renewable energy sources. The charging station would wirelessly transmit power from solar panels to electric vehicles using inductive coupling between transmitter and receiver coils. When an IR sensor detects a vehicle entering the station, a relay is activated to allow power from batteries charged by the solar panels to pass through the primary coil. This would wirelessly charge the vehicle by generating electromagnetic flux between the coils. The system aims to promote sustainable transportation through solar-powered wireless charging of electric vehicles.
A Review on Electric Vehicle Charging SystemsIRJET Journal
This document reviews electric vehicle charging systems. It discusses different types of chargers and charging methods, including onboard and off-board chargers. It also covers battery management systems and their functions in monitoring battery state, balancing cells, and ensuring safety. The document reviews literature on electric vehicle charger topologies and control algorithms. It aims to understand lithium-ion battery operation and charging, accurately determine state of charge, and design an intelligent onboard level 1 charging system and automatic payment system. Level 1 charging uses a standard outlet but is slow, making it suitable for multi-unit dwellings and backup charging. Pricing strategies can influence when drivers remove fully charged vehicles from stations.
DATA DRIVEN ANALYSIS OF ENERGY MANAGEMENT IN ELECTRIC VEHICLESvivatechijri
Inevitably, there has been a concerted policy push at the national level to promote electric vehicles. In electric vehicles, the progress stands and falls with the performance of the battery. Lithium-ion batteries are considered in this research project, as they are the most crucial component in the electric vehicle power system and require accurate monitoring and control. Proper battery optimization in electric vehicles requires a meticulous energy management system. The energy management system is bound for estimating the battery state of charge, state of health, various distinct factors in the system, and subsystems in real-time. The state of charge estimation accounts for the prevention of over-charge and over-discharge of batteries and provides cell balancing. Traditional SOC estimation approaches, such as open-circuit voltage (OCV) measurement and current integration (coulomb counting), are relatively accurate in some cases. However, estimating the SOC for Li-ion chemistries requires a modified approach. This project presents the Kalman filtering algorithm for the state of charge estimation that provides precise results for a fair computational effort.
IRJET - Wireless Charging of Electric VehicleIRJET Journal
This document discusses wireless charging of electric vehicles. It begins with an introduction to wireless charging and its benefits over plug-in charging. It then describes the basic principles of inductive wireless power transfer used for wireless charging. It discusses both static wireless charging systems that can be implemented in parking lots and garages, as well as dynamic wireless charging systems that charge EVs while in motion. The document outlines the components and circuitry required for wireless charging systems. It also discusses some challenges with wireless charging including infrastructure costs and limitations on power transfer over distance. Finally, it presents the future potential for widespread implementation of wireless charging to improve adoption of electric vehicles.
IRJET - OR-DEV System (On Road Dynamic Charging for Electric Vehicles)IRJET Journal
This document summarizes a research paper on a proposed wireless charging system for electric vehicles called OR-DEV (On Road Dynamic Charging for Electric vehicles). It introduces an inductive wireless charging lane for EVs with embedded coils that would allow continuous charging of EVs as they drive on the roadway. The system aims to address limitations of traditional electric charging by reducing charging times and not requiring EVs to stop for charging. It presents the background on electric vehicles and motivation for dynamic wireless charging. The system architecture and initial simulation results showing high charging efficiency are summarized. The document also reviews related work on wireless charging systems and discusses how the proposed system could increase EV mileage and reduce waiting times for charging.
Grid reactive voltage regulation and cost optimization for electric vehicle p...nooriasukmaningtyas
Expecting large electric vehicle (EV) usage in the future due to environmental issues, state subsidies, and incentives, the impact of EV charging on the power grid is required to be closely analyzed and studied for power quality, stability, and planning of infrastructure. When a large number of energy storage batteries are connected to the grid as a capacitive load the power factor of the power grid is inevitably reduced, causing power losses and voltage instability. In this work large-scale 18K EV charging model is implemented on IEEE 33 network. Optimization methods are described to search for the location of nodes that are affected most due to EV charging in terms of power losses and voltage instability of the network. Followed by optimized reactive power injection magnitude and time duration of reactive power at the identified nodes. It is shown that power losses are reduced and voltage stability is improved in the grid, which also complements the reduction in EV charging cost. The result will be useful for EV charging stations infrastructure planning, grid stabilization, and reducing EV charging costs.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Simulation studies on developed Solar PV Array based Multipurpose EV Charger ...IRJET Journal
This document describes a solar photovoltaic array-powered electric vehicle charger that can operate in both grid-connected and standalone modes. The charger is designed to charge EVs using power from the PV array or grid. It can also power local household loads using PV, EV, or grid power. The charger controls include maximum power point tracking for the PV array, regulation of the DC bus voltage, synchronization between the grid and charger voltages, and seamless switching between operating modes. Simulation studies were conducted to validate the charger's multipurpose and integrated functionality. The charger aims to make better use of distributed energy resources while providing uninterruptible power for EV charging and household loads.
DESIGN AND SIMULATION OF SOLAR BASED FAST CHARGING STATION FOR ELECTRIC VEHIC...IRJET Journal
This document discusses the design and simulation of a solar-based fast charging station for electric vehicles using MATLAB. It aims to provide a reliable and sustainable charging solution by integrating solar PV panels, energy storage batteries, power electronics components like DC-DC converters and inverters, and advanced control strategies. The design process involves sizing the solar panels to generate sufficient power for fast charging and ensuring continuous power availability through an energy storage system. Power flow is efficiently managed between the solar panels, batteries, and EV charging units through electronic components and control strategies that regulate the charging process based on battery state of charge and other factors.
DESIGN OF A RELIABLE AND PERFORMANCE FOCUSED ELECTRIC MOTORCYCLEIRJET Journal
This document describes the design of an electric motorcycle. It aims to create a reliable and high-performance electric motorcycle that overcomes issues with previous electric vehicles like limited range. The document outlines the key components of the proposed electric motorcycle design, including the chassis, swing arm, steering, suspension system, brushless DC hub motor, wheels, motor controller, brakes, battery and battery management system. It provides details on the specifications and technical requirements for these components. The goal is to develop an electric motorcycle with high efficiency that maintains performance even when battery power is low.
1. The current trends in EV charging systems are focusing on making charging faster and more convenient through technologies like wireless charging, fast charging networks, and smart charging systems.
2. Key types of EV charging systems include level 1 and level 2 charging using cables, DC fast charging, and wireless charging. Emerging trends include vehicle-to-grid technology, ultra-fast charging, battery swapping, solar-powered charging, and smart charging.
3. Government policies play an important role through financial incentives for EVs and charging infrastructure mandates. Regulations like ZEV mandates are aimed at increasing EV adoption and reducing emissions.
Renewable Energy Integration in Smart Grids: A Review of Recent Solutions to ...IRJET Journal
This document provides a review of recent solutions to integrating renewable energy into smart grids. It identifies the most prevalent issues with renewable energy integration, such as the intermittency of sources like solar and wind power, and issues with grid voltage and frequency stability. It then summarizes several selected solutions that have been proposed to address these challenges, including using energy storage systems, advanced inverters, machine learning for power forecasting, and systems to improve grid stability like synchronverters. The review concludes that while progress has been made in renewable energy integration, continued work is still needed to fully address the multidimensional problems involved.
APPLICATION OF PHEVs FOR SMART GRID IN INDIAN POWER SECTOR1Eshwar Pisalkar
This document discusses the application of plug-in hybrid electric vehicles (PHEVs) for smart grids in the Indian power sector. It describes how PHEVs can help with demand side management by charging from renewable energy sources and providing power back to the grid. The document also examines issues like harmonic distortion caused by PHEV charging and its impact on transformers. It proposes a distributed strategy for PHEV charging and discharging that involves regional dispatch centers and charging stations. Finally, it suggests that introducing electric 2-wheelers widely in India first could significantly reduce household power demand.
Wireless Power Transfer for Electric CarsIRJET Journal
This document discusses a proposed wireless power transfer system for charging electric vehicles in parking facilities. The system uses inductive coupling between transmitting and receiving coils to wirelessly charge electric vehicle batteries. It also implements RFID technology for users to pay for charging and parking via an online account. The system is designed to be installed in existing parking structures to add wireless charging capabilities without needing to build new infrastructure. It has the potential to improve the electric vehicle charging experience and support increased EV adoption.
Wireless Power Transfer for Electric CarsIRJET Journal
This document discusses a proposed wireless power transfer system for charging electric vehicles in parking facilities. The system uses inductive coupling between transmitting and receiving coils to wirelessly charge electric vehicle batteries. It also implements RFID technology for users to pay for charging and parking via an online account. The system is designed to be installed in existing parking structures to add wireless charging capabilities without needing to build new infrastructure. It has the potential to improve the electric vehicle charging experience and support increased EV adoption.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Adverse effects of fossil fuel burning and internal combustion engine vehicles have alarmed nations worldwide. Governments are taking steps to promote the use of Electric Vehicles due to less carbon emissions and to pacify the environmental issues. The added load of Electric Vehicles poses a threat to the existing grid which leads to instability of the grid. The problem of demand supply mismatching can be solved by integrating the renewable energy sources with Electric vehicle charging station resulting in bi-directional flow of power. Vehicle to Grid technology helps the utility with active and reactive power support by feeding power from battery pack to grid and vice versa. Vehicle to Grid describes a system in which electric vehicles, plug-in hybrid, fuel cells electric vehicles are connected to the power grid to provide high power, spinning reserves, regulation services etc. The perspective of this study is to evolve a smart charging schedule based on the load on grid, time of use of the EV and other factors in order to minimize cost of charging for electric utilities and EVs as well as promote profits to EV owners.
This document discusses developing an information model to connect electric vehicle supply equipment (EVSEs) to customer energy management systems (CEMS) through the Energy Information Standards Alliance. The model would allow two-way communication between EVSEs and CEMS to facilitate demand response and other grid services. Integrating EVSEs with CEMS could help manage electric vehicle charging load and make use of stored vehicle energy for applications like peak shaving and renewable energy firming.
Electric vehicle (EV) charging station powered by the scattered energy sources with DC Nanogrid (NG) provides an option for uninterrupted charging. The NG powered by the renewable energy sources (RES) of photovoltaic (PV) and wind energy. When the excess power produced by the renewable energy stored in the local energy storage unit (ESU) utilized during shortage power from the renewable sources. During the overloading of NG and demand of energy in ESU; the mobile charging station (MCS) provides an uninterrupted charging. The MCS provides an option for battery swapping and vehicle to grid feasibility. The MCS required to monitor the state of charge (SOC) and state of health (SOH) of the battery. Monitoring of SOC and SOH related to the various battery parameters like voltage, current and temperature. A laboratory prototype is developed and tested the practical possibility of EV to NG and Internet of things (IoT) based monitoring of battery parameters.
This document presents a proposed eco-friendly charging station project that uses renewable energy sources. The charging station would wirelessly transmit power from solar panels to electric vehicles using inductive coupling between transmitter and receiver coils. When an IR sensor detects a vehicle entering the station, a relay is activated to allow power from batteries charged by the solar panels to pass through the primary coil. This would wirelessly charge the vehicle by generating electromagnetic flux between the coils. The system aims to promote sustainable transportation through solar-powered wireless charging of electric vehicles.
A Review on Electric Vehicle Charging SystemsIRJET Journal
This document reviews electric vehicle charging systems. It discusses different types of chargers and charging methods, including onboard and off-board chargers. It also covers battery management systems and their functions in monitoring battery state, balancing cells, and ensuring safety. The document reviews literature on electric vehicle charger topologies and control algorithms. It aims to understand lithium-ion battery operation and charging, accurately determine state of charge, and design an intelligent onboard level 1 charging system and automatic payment system. Level 1 charging uses a standard outlet but is slow, making it suitable for multi-unit dwellings and backup charging. Pricing strategies can influence when drivers remove fully charged vehicles from stations.
DATA DRIVEN ANALYSIS OF ENERGY MANAGEMENT IN ELECTRIC VEHICLESvivatechijri
Inevitably, there has been a concerted policy push at the national level to promote electric vehicles. In electric vehicles, the progress stands and falls with the performance of the battery. Lithium-ion batteries are considered in this research project, as they are the most crucial component in the electric vehicle power system and require accurate monitoring and control. Proper battery optimization in electric vehicles requires a meticulous energy management system. The energy management system is bound for estimating the battery state of charge, state of health, various distinct factors in the system, and subsystems in real-time. The state of charge estimation accounts for the prevention of over-charge and over-discharge of batteries and provides cell balancing. Traditional SOC estimation approaches, such as open-circuit voltage (OCV) measurement and current integration (coulomb counting), are relatively accurate in some cases. However, estimating the SOC for Li-ion chemistries requires a modified approach. This project presents the Kalman filtering algorithm for the state of charge estimation that provides precise results for a fair computational effort.
IRJET - Wireless Charging of Electric VehicleIRJET Journal
This document discusses wireless charging of electric vehicles. It begins with an introduction to wireless charging and its benefits over plug-in charging. It then describes the basic principles of inductive wireless power transfer used for wireless charging. It discusses both static wireless charging systems that can be implemented in parking lots and garages, as well as dynamic wireless charging systems that charge EVs while in motion. The document outlines the components and circuitry required for wireless charging systems. It also discusses some challenges with wireless charging including infrastructure costs and limitations on power transfer over distance. Finally, it presents the future potential for widespread implementation of wireless charging to improve adoption of electric vehicles.
IRJET - OR-DEV System (On Road Dynamic Charging for Electric Vehicles)IRJET Journal
This document summarizes a research paper on a proposed wireless charging system for electric vehicles called OR-DEV (On Road Dynamic Charging for Electric vehicles). It introduces an inductive wireless charging lane for EVs with embedded coils that would allow continuous charging of EVs as they drive on the roadway. The system aims to address limitations of traditional electric charging by reducing charging times and not requiring EVs to stop for charging. It presents the background on electric vehicles and motivation for dynamic wireless charging. The system architecture and initial simulation results showing high charging efficiency are summarized. The document also reviews related work on wireless charging systems and discusses how the proposed system could increase EV mileage and reduce waiting times for charging.
Grid reactive voltage regulation and cost optimization for electric vehicle p...nooriasukmaningtyas
Expecting large electric vehicle (EV) usage in the future due to environmental issues, state subsidies, and incentives, the impact of EV charging on the power grid is required to be closely analyzed and studied for power quality, stability, and planning of infrastructure. When a large number of energy storage batteries are connected to the grid as a capacitive load the power factor of the power grid is inevitably reduced, causing power losses and voltage instability. In this work large-scale 18K EV charging model is implemented on IEEE 33 network. Optimization methods are described to search for the location of nodes that are affected most due to EV charging in terms of power losses and voltage instability of the network. Followed by optimized reactive power injection magnitude and time duration of reactive power at the identified nodes. It is shown that power losses are reduced and voltage stability is improved in the grid, which also complements the reduction in EV charging cost. The result will be useful for EV charging stations infrastructure planning, grid stabilization, and reducing EV charging costs.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Simulation studies on developed Solar PV Array based Multipurpose EV Charger ...IRJET Journal
This document describes a solar photovoltaic array-powered electric vehicle charger that can operate in both grid-connected and standalone modes. The charger is designed to charge EVs using power from the PV array or grid. It can also power local household loads using PV, EV, or grid power. The charger controls include maximum power point tracking for the PV array, regulation of the DC bus voltage, synchronization between the grid and charger voltages, and seamless switching between operating modes. Simulation studies were conducted to validate the charger's multipurpose and integrated functionality. The charger aims to make better use of distributed energy resources while providing uninterruptible power for EV charging and household loads.
DESIGN AND SIMULATION OF SOLAR BASED FAST CHARGING STATION FOR ELECTRIC VEHIC...IRJET Journal
This document discusses the design and simulation of a solar-based fast charging station for electric vehicles using MATLAB. It aims to provide a reliable and sustainable charging solution by integrating solar PV panels, energy storage batteries, power electronics components like DC-DC converters and inverters, and advanced control strategies. The design process involves sizing the solar panels to generate sufficient power for fast charging and ensuring continuous power availability through an energy storage system. Power flow is efficiently managed between the solar panels, batteries, and EV charging units through electronic components and control strategies that regulate the charging process based on battery state of charge and other factors.
DESIGN OF A RELIABLE AND PERFORMANCE FOCUSED ELECTRIC MOTORCYCLEIRJET Journal
This document describes the design of an electric motorcycle. It aims to create a reliable and high-performance electric motorcycle that overcomes issues with previous electric vehicles like limited range. The document outlines the key components of the proposed electric motorcycle design, including the chassis, swing arm, steering, suspension system, brushless DC hub motor, wheels, motor controller, brakes, battery and battery management system. It provides details on the specifications and technical requirements for these components. The goal is to develop an electric motorcycle with high efficiency that maintains performance even when battery power is low.
1. The current trends in EV charging systems are focusing on making charging faster and more convenient through technologies like wireless charging, fast charging networks, and smart charging systems.
2. Key types of EV charging systems include level 1 and level 2 charging using cables, DC fast charging, and wireless charging. Emerging trends include vehicle-to-grid technology, ultra-fast charging, battery swapping, solar-powered charging, and smart charging.
3. Government policies play an important role through financial incentives for EVs and charging infrastructure mandates. Regulations like ZEV mandates are aimed at increasing EV adoption and reducing emissions.
Renewable Energy Integration in Smart Grids: A Review of Recent Solutions to ...IRJET Journal
This document provides a review of recent solutions to integrating renewable energy into smart grids. It identifies the most prevalent issues with renewable energy integration, such as the intermittency of sources like solar and wind power, and issues with grid voltage and frequency stability. It then summarizes several selected solutions that have been proposed to address these challenges, including using energy storage systems, advanced inverters, machine learning for power forecasting, and systems to improve grid stability like synchronverters. The review concludes that while progress has been made in renewable energy integration, continued work is still needed to fully address the multidimensional problems involved.
APPLICATION OF PHEVs FOR SMART GRID IN INDIAN POWER SECTOR1Eshwar Pisalkar
This document discusses the application of plug-in hybrid electric vehicles (PHEVs) for smart grids in the Indian power sector. It describes how PHEVs can help with demand side management by charging from renewable energy sources and providing power back to the grid. The document also examines issues like harmonic distortion caused by PHEV charging and its impact on transformers. It proposes a distributed strategy for PHEV charging and discharging that involves regional dispatch centers and charging stations. Finally, it suggests that introducing electric 2-wheelers widely in India first could significantly reduce household power demand.
Wireless Power Transfer for Electric CarsIRJET Journal
This document discusses a proposed wireless power transfer system for charging electric vehicles in parking facilities. The system uses inductive coupling between transmitting and receiving coils to wirelessly charge electric vehicle batteries. It also implements RFID technology for users to pay for charging and parking via an online account. The system is designed to be installed in existing parking structures to add wireless charging capabilities without needing to build new infrastructure. It has the potential to improve the electric vehicle charging experience and support increased EV adoption.
Wireless Power Transfer for Electric CarsIRJET Journal
This document discusses a proposed wireless power transfer system for charging electric vehicles in parking facilities. The system uses inductive coupling between transmitting and receiving coils to wirelessly charge electric vehicle batteries. It also implements RFID technology for users to pay for charging and parking via an online account. The system is designed to be installed in existing parking structures to add wireless charging capabilities without needing to build new infrastructure. It has the potential to improve the electric vehicle charging experience and support increased EV adoption.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELijaia
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Prediction of Electrical Energy Efficiency Using Information on Consumer's Ac...PriyankaKilaniya
Energy efficiency has been important since the latter part of the last century. The main object of this survey is to determine the energy efficiency knowledge among consumers. Two separate districts in Bangladesh are selected to conduct the survey on households and showrooms about the energy and seller also. The survey uses the data to find some regression equations from which it is easy to predict energy efficiency knowledge. The data is analyzed and calculated based on five important criteria. The initial target was to find some factors that help predict a person's energy efficiency knowledge. From the survey, it is found that the energy efficiency awareness among the people of our country is very low. Relationships between household energy use behaviors are estimated using a unique dataset of about 40 households and 20 showrooms in Bangladesh's Chapainawabganj and Bagerhat districts. Knowledge of energy consumption and energy efficiency technology options is found to be associated with household use of energy conservation practices. Household characteristics also influence household energy use behavior. Younger household cohorts are more likely to adopt energy-efficient technologies and energy conservation practices and place primary importance on energy saving for environmental reasons. Education also influences attitudes toward energy conservation in Bangladesh. Low-education households indicate they primarily save electricity for the environment while high-education households indicate they are motivated by environmental concerns.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
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Transactions on Industry Applications
1
Electrical Safety Considerations in Large-Scale
Electric Vehicle Charging Stations
Bo Wang, Student Member, IEEE, Payman Dehghanian, Member, IEEE, Shiyuan Wang, Student Member, IEEE
and Massimo Mitolo, Senior Member, IEEE
Abstract—Several safety regulations particularly concerning
the charging electric vehicles (EVs) are developed to ensure
the electric safety and prevent the hazardous accidents, in
which safety requirements for electric vehicle supply equipment
(EVSE) and the EV battery are the two main driving factors. At
present, quantitative assessment of electrical safety considering
the operation conditions of large-scale electric vehicle charging
stations (EVCSs) has still remained a challenge. Driven by the
hierarchy of hazard control mechanisms, this paper proposes a
holistic approach to evaluate the electrical safety of the large-
scale EVCSs when coupled to renewable power generation. Our
approach mainly focuses on several topics on the operational
safety of EVCS primarily concerning: (1) the facility degradation
which could potentially result in a compromised EVSE reliability
performance and EVCS protection failure; (2) the cyber-attack
challenges when the smart charging and the communication
between EVCSs and electric utilities are enabled; (3) the potential
mismatch between the renewable output and EVCS demand,
which could trigger the system stability challenges during normal
operation and inability to supply the critical EV loads dur-
ing outages. The proposed framework will provide informative
guidelines to the EVCS operators for continuous monitoring and
effective management of the day-to-day EVCSs operation.
Index Terms—Electric vehicle (EV); electric vehicle charging
station (EVCS); risk management; electrical safety.
I. INTRODUCTION
TRANSPORTATION sector consumes a large portion of
fossil fuel with massive air pollution and greenhouse
gas emissions, which has raised significant environmental
concerns. Organizations and governments have set ambitious
targets for the integration of electric vehicles (EVs) into the
modern power grids to build, plan, and operate a clean and
sustainable energy landscape [1]. With the decreasing cost of
EVs, the number of EVs has increased dramatically, many EV
charging facilities have been constructed, and many large EV
charging stations (EVCSs) are being designed and planned
to manage the charging needs of hundreds of EVs that are
seamlessly integrated in the modern power grids of the future.
Many standards and regulation policies related to safely
operating an EV have been published, where the primary
focuses are on the battery pack, the plugs and connectors,
and the electric vehicle supply equipment (EVSE) [2]. EV
battery performance and safety are considered by the vehicle
B. Wang, P. Dehghanian and S. Wang are with the Department of
Electrical and Computer Engineering, The George Washington University,
Washington, DC 20052 USA (e-mail: wangbo@gwu.edu; payman@gwu.edu;
shiyuan1225@gwu.edu).
M. Mitolo is with the Electrical Engineering Department at the Irvine Valley
College, Irvine, CA 92618, USA (email: mitolo@ieee.org).
manufacturers to prevent the battery from combustion, explo-
sion, and other potential accidents resulted from the failure
and miss-operation of the battery itself [3]. The plugs and
connectors, and the EVSE with electrical safety protection
features have also been addressed in several standards from
a safety standpoint. For instance, the Society of Automotive
Engineering (SAE) has published its recommended practices
for charging the plug-in EVs (PEVs). The SAE J1772 stan-
dard covers the general physical, electrical, and performance
requirements for the EV charging systems in North America
[4]. The SAE J3068 standard allows the EVs to fully utilize
three-phase AC power to charge the batteries. A high degree
of safety is recommended for the charging operation mode of
the PEVs to comply with the standards requirements [5].
The electrical safety considerations of EVCSs from the
perspective of an EVCS operator are also investigated by
policy and research communities. Guidelines are introduced
requiring the EVCS design to meet the aforementioned stan-
dards requirements, and the EVCSs are also required to be
subject to periodic safety assessments [6]. Fire safety when
charging EVs is discussed in [7]. The transformer loss-of-life
due to the uncoordinated PEV charging in a parking garage
has been analyzed in [8]. The integration of photovoltaic (PV)
system and the use of smart charging algorithms can avoid
the transformer aging and early replacements. An advanced
communication system for EVCSs brings about additional
opportunities for the EVCS operator, where a communication
assisted protection strategy can alleviate the faults and ensure
a safe charging of the EVCS [9]. In [10], the cloud has been
used as a platform for online monitoring and analysis of the
EVCS data and power quality assessments.
EVCSs can also play an important role in power systems
when the communication-assisted smart charging algorithms
are deployed. Communications between the EVCS and the
utility allow the EVCSs to effectively respond to the utility
signals during the system transient operating states, acting
as distributed energy resources (DERs) and achieved through
effective control of EVs’ charging and discharging schedules.
The communication between the EVSE and the smart meters
connected to EVs also enables the EVCS to manage the
charging schedule of PEVs so that the EVs can mainly charge
the batteries during the off-peak hours with low electricity
prices. It will also increase the grid flexibility by dispatching
the EV loads. The contribution of EVCSs to maintain the grid
stability and enhance its flexibility will be significant with the
increasing penetration of EVs in the coming future.
While the EVCSs with communication systems enable ad-
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Transactions on Industry Applications
2
ditional benefits to EVCS operators and the grid performance,
this cyber-physical system reveals significant challenges to the
its own operation as well as the grid performance and has
to be well investigated to ensure a safe and secure operation
of both. Several research efforts have focused on modeling
the cyber-physical power systems and evaluating the impacts
[11], [12]. The cyber security and cyber reliability of the
distribution systems and the demand side are also studied
in [13]–[15]. The EVCS design should also consider the
security and reliability of its cyber-physical system and its
impacts on the system stability performance. These factors
are interdependent [16], [17], and the risk may increase if
such factors and their correlation are ignored through the
EVCS design and procurement practices. Risk assessment
for power dispatch considering the uncertainty in intermittent
wind and PV power output has been studied in [18], [19]
to address and quantify the cost of expected energy not
supplied (EENS) in the system. EV load characteristics should
also be considered during the EVCS design procedures to
address the prescribed safety requirements for the EVCSs
during the operation. Since the EV customer behaviour and
the corresponding load have different power supply reliability
requirements, inability to supply some critical EV loads may
cause catastrophic consequences in the grid operation.
The EVCS safety depends on how well the risk management
and control mechanisms are implemented within the design
processes to prevent the hazardous conditions and catastrophic
consequences [20]. Centered on the hierarchy of risk control
measures [21] that are widely used in safety management
systems, we propose a systematic approach to evaluate the
electrical safety of EVCSs. The paper’s main contributions
are summarized as follows:
1) We introduce an EVCS architecture and address the
EVCS safety considerations in its cyber-physical system
and its interactions with the power grid.
2) We discuss the interdependence of the safety require-
ments with the EVCSs operation and develop a risk
assessment framework to evaluate its electrical safety.
The paper is organized as follows. Section II presents
the suggested EVCS architecture. Section III presents its
electrical safety considerations and introduces the developed
risk assessment model for EVCSs. Section IV presents the
numerical case studies and simulation results, followed by the
concluding remarks in Section V.
II. THE ARCHITECTURE OF AN EVCS
With the emerging advancements in the EV charging tech-
nologies, there are three main methods [22] widely used to
charge an EV: (i) conductive charging, where the battery is
connected by a cable and plugged directly into an EVSE; (ii)
inductive charging, also called wireless charging, where the
electricity is transferred through an air gap from one magnetic
coil in the charger to a second magnetic coil fitted into the car;
and (iii) battery exchange, by swapping the EV battery with
fresh ones in a battery swapping station (BSS). The conductive
charging is currently preferred by the EV operators due to
its lower cost, higher efficiency, and simpler business model.
Some testbeds based on the conductive charging mechanism
have been built to test the operation of large EVCSs, for
instance, the EVCS at the Argonne National Laboratory with
7 EVSEs [23] and the EVCS in Caltech with 54 EVSEs [24].
A. EV Charging Standards and Requirements
The charging level describes the power level of a charging
outlet using conductive charging mechanisms. Based on the
SAE J1772 in 2017 [25], there are two AC and two DC
charging levels as follows:
1) AC Level 1, also known as home charging, supports the
voltage level of 120 V with max current level of 16 A.
2) AC Level 2, supports 208–240 V and the maximum
current is 80 A. As the maximum power here is 19.2
kW, it may be utilized at home, workplace and public
charging facilities.
3) DC level 1, with the DC output voltage of 50–1000 with
the maximum current of 80 A.
4) DC level 2, with the same DC output voltage as DC
level 1, but a maximum current that can reach 400 A.
While both AC levels require the EV with an on-board charger
to receive the single-phase AC power from the EVSE, the DC
levels charge the EV battery directly with DC power using off-
board charging, where the DC power can be converted from
both single and three phase AC power supply of the utility. In
contrast to the SAE J1772, SAE J3068 in 2018 is a recom-
mended practice for conductive charging that utilizes three-
phase AC power. Presenting a symmetric three-phase load
enhances the grid stability, especially at high power levels. The
SAE J3068 standardizes an AC three-phase capable charging
Coupler and digital control protocols, offering sufficient power
and reliability for the commercial vehicle market with heavy-
duty vehicles [26].
With bidirectional digital communications between the EV
and the EVSE via single-wire base-band signaling for local
control, a large three-phase EVCS provides low-cost, less-
complex, and highly-reliable charging of EVs. It can also
supply both AC and DC power based on the customer prefer-
ences. Furthermore, large three-phase EVCSs using conductive
charging can operate as DERs to support the grid. The IEEE
Standard 1547 in 2018 provides requirements relevant to
the performance, operation, testing, safety considerations, and
maintenance of the interconnection between utility electric
power systems (EPSs) and the DERs. The requirements are
universally needed for interconnection of different types of
DERs [27], where inability to address such requirements may
lead to cascading failures in power systems. For instance,
tripping of wind farms during a storm resulted in a major
blackout in South Australia in 2016, affecting 650,000 cus-
tomers [28]. Thus, it requires the EVCS operators to not only
account for the traditional considerations of the EVSEs, but
also capturing the safety of the EVCS cyber-physical system
and their interactions with the grid.
B. The Proposed EVCS Architecture
We aim at large-scale EVCSs, corresponding to the long-
term-parking locations, such as parking garages and parking
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Transactions on Industry Applications
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Operation State
Fig. 1. The overall architecture of an EVCS.
lots. These EVCSs typically offer 5 kW to 25 kW charging ca-
pacity through EVSEs (some of them may also offer charging
power of 26–60 kW). Only a few EVSEs with the charging
capacity of more than 60 kW will be installed by the EVCS
operators as the EVSEs with very high charging capacity come
at higher installation costs [29], higher degradation of the
battery life cycle, and higher charging cost as they may get
charged during peak hours with premium electricity price. An
EVCS with several EVSEs are typically consisted of three
parts: (i) the physical system that provides the EV charging
services, (ii) the communication system, and (iii) the control
center. In compliance with the recent recommended practices
and standards, an architecture for a large EVCS is proposed to
manage charging of tens to hundreds of EVs that also act as
DERs in the grid. The proposed architecture considering the
EVCS cyber-physical system is shown in Fig. 1.
The EVCS’s physical system is demonstrated in black and
is connected to the distribution grid through a step down
transformer. An LC filter is used to filter out harmonics and
a voltage source converter (VSC) is used as the AC/DC
converter to maintain the dc-link voltage of the capacitor
and control the reactive power. The VSC can operate in
four-quadrant, and the reactive power injection/absorption is
accomplished with the dc-link capacitor. Bi-directional DC/DC
converter is used to control the active power. While most cur-
rent EVSEs have independent AC/DC converters and connect
separately to the AC busbar, the EVSEs can share the same
AC/DC converter and have multiple parallel DC/DC converters
on the DC busbar when EVs are charged with DC power.
The communication system is illustrated in blue. The cyber
system transmits the signals between the physical system and
the control center. Direct load control can be achieved by
enabling and disabling the EV charging, or through propor-
tional adjustments in the duty cycle of the DC/DC converter.
The control center can coordinate the load control of EVs
to enable smart charging, and the EVCS can participate into
the utility demand side management programs as a DER. The
control center will also communicate other signals with the
utility. Many EVCS operators analyze the data and run the
EV scheduling algorithms on the cloud [23], [24], and thus,
N
Check
Signals
Y
Trip
Monitor
Y
Disable permit
service
Abnormal
conditions
Normal
operation
N
Y
Ride-through
Tripping
requirements
Y Tripping
requirements
N
N
Momentary
Cessation
Tripping
requirements
Y
N
Ride-through
Ride-through
requirements
Mode selection
Parameter settings
Fig. 2. The EVCS operation states and priority diagram as a DER.
Fig. 3. A recommended ride-through priority and mode selection diagram.
the communication between the EVCS and the cloud is also
enabled.
The control center with a site monitor and the operation and
control platform can monitor and control the EVCS directly
or implement the signals sent from the utility and the cloud.
Based on the IEEE Std 1547-2018, a DER shall change the
operation state based on the DER response priorities. Different
operation states of the DER are illustrated in Fig. 2. The
EVCS operator checks the communication signals and grid
conditions to decide on the operating states. For instance, the
EVCS should trip in no more than 2 s when it receives the
signals from the utility to disable permit service. The control
center can also adjust the active/reactive power management
modes based on the operation requirements. According to the
standard, there are two active power management modes and
four reactive power management modes for DERs. The DER
can select different control modes during normal operation
conditions and ride-through based on the ride-through priority.
A recommended ride-through priority and mode selection
diagram is shown in Fig. 3. The voltage-active power mode
is disabled in default. Once the mode is on, e.g., if the Active
Power Mode Selection Signal ’-1’ is sent from Area EPS to
the DER operator, a Switch will select the second data signal
and the Compare function will then select the lesser of the
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Transactions on Industry Applications
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power value between the frequency-droop mode and voltage-
active power mode. Reactive power control functions include
Constant power factor mode, Voltage-reactive power mode,
Active power-reactive power mode and Constant reactive
power mode. The DER needs to be capable of activating each
mode one at a time. Multiport Switch is used to achieve this
selection, e.g., if Reactive Power Mode Selection Signal ’1’ is
sent from Area EPS to the DER operator, port 1 is selected,
and then the voltage-reactive power mode is activated. Con-
stant power factor mode with unity power factor setting is the
default mode of the installed DER, thus Signal ’4’ is selected
in the default mode.
III. PROPOSED RISK MANAGEMENT MODEL FOR EVCSS
The proposed risk management framework of the EVCS
is shown in Fig. 4 and includes three layers: (i) safety
considerations of EVCS, (ii) risk assessment, and (iii) risk
control. The safety considerations in different layers of EVCS
are explored, risk assessment analytics are suggested, and
finally the integrated analysis and comparisons are done in
the design and planning procedures to meet the requirements
of the hierarchy of risk control measures.
A. Safety Considerations and Mitigation Methods
The electrical safety offered by the EVSE can be defined,
as the probability that it will continue to properly carry out
its duties without causing a dangerous voltage to appear on
a touchable surface due to random faults. Some faults may
compromise safety, but not the functionality of the charger,
which may keep working. This very hazardous situation is
even more crucial in large-scale EVCSs, which are publicly
exposed. Because electrical safety of the EVCS decays in time,
it should be be assessed to prevent the hazardous situations
such as people injury, device damage, unstable operation of
the grid, and the discontinuity of power supply to EV load.
Safety considerations in Fig. 4 include all three layers of the
EVCS. The reliability of the EVCS components, cyber security
of communications, and flexibility of EVCS operation should
be considered to reduce the risk and mitigate the impacts of
the potential hazards.
The conductive charging requires the customers to plug-
in their EVs to the EVSEs, and thus, the EVSE design
should protect the customer against electric shock when the
EV is being charged. The protection against electric shock is
achieved by implementing two layers of protection: the basic
protection (i.e., preventing persons from being in contact with
energized parts) and fault protection (i.e., protection in the
event of failure of the basic insulation), which is generally
obtained via disconnection of the supply. The International
Electrotechnical Commission (IEC) defines different charging
modes and describes the safety communication protocol be-
tween EV and EVSE [30]. Charging mode 3 should be used
for AC charging, and charging mode 4 should be used for
the fast DC charging in large-scale EVCSs. The two charging
modes have control and protection functions installed perma-
nently. The reliability of the EVSE components with electrical
safety protection features should also be monitored by the
control center and assessed by periodic safety inspections.
For instance, the potential failure of Ground Fault Circuit
Interrupter breaker or charging circuit interrupting devices
due to environmental factors (e.g., humidity and aging), or
vandalism activities like copper theft, can create a dangerous
situation for EV customers when they are in touch with the
EVSE. The cyber reliability is also very important to the
EVCS: if the router is down, the EV load management signals
could not be implemented, and the communication between
the utility and the EVCS also fails. Hence, a very large EVCS
should have backup router and battery resources to support the
EVCS communication system at minimum cost.
A well-designed protection system in EVCS to have a
swift fault clearance is also one main factor to ensure the
EV charging safety and protect the EVCS equipment. Over
current protection is a major protection function for EVCSs.
Adaptive protection with the communication assistance is
recommended to coordinate the protection devices and to
change the protection algorithms of circuit breakers when
necessary [9], [31]. However, performance of the adaptive
protection primarily relies on the EVCS cyber layer. In cases
of delays in signal communications (or cyber system) and
protection device failure, the risk will increase significantly.
Hence, hierarchical protection design, in which the upper
layer acts as the backup protection for the lower layer, should
still be featured and embedded in the adaptive protection to
account for communication failure. The use of communication
also makes the EVCS protection vulnerable to cyber attacks.
The attacker may disable the protective devices which may
potentially compromise the electric safety. Corrective protec-
tion should be used to safeguard the EVCS if the adaptive
protection devices fail to trip. For example, the power devices
like IGBTs can switch off when they reach their current
limits. In addition, with the EVCS cyber-physical system, the
circuit breaker conditions can be uploaded to the EVCS control
center, which can guide necessary maintenance and life-cycle
management using condition monitoring data [32]. Algorithms
to detect the device malfunction and cyber attacks can also be
developed to enable the EVCS control center to monitor its
performance at all times. Suitable fire detection and warning
systems should be installed to detect fire scenarios during the
charging, which may also be contributed by other factors (e.g.,
high temperature in summer).
The cyber attack to the internal communication system of
EVCSs or the advanced metering infrastructure (AMI) that
enables the communication between utility and EVCSs could
also affect the grid stability. For example, the attacker can
send the disabling permit service signal to trip the EVCS
from the grid. This may cause cascading failures when the
grid operates in a marginal operating condition. The attacks
targeting the EVCS internal communication system and AMI
may have limited impact, and the likelihood of manipulating
the communication between the utility and the EVCS may
be low when the utility connects the DERs using isolated
optical fiber systems. However, the EV load management and
control employing cloud services expose the EVCS and the
grid with additional vulnerabilities to cyber threats and outside
intruders. Particularly, the great exposure and interactions of
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Fig. 4. The risk management framework for the EVCSs.
the EVCS energy management systems and the public internet
will change the communication system in power grids from
isolated systems to the attack and defend mode, giving birth to
a myriad of cyber threats. For example, the distributed denial-
of-service (DDoS) attack can coordinate the DoS attacks
to cause serious delays or failures in the data transmission
between EVCSs and clouds. As a result, the EVCSs may not
respond to the frequency disturbances and fail to coordinate
with the main grid services during the ride-through operation.
The attacker can also send signals to EVCSs to continuously
switch on/off the EV load and thereby can cause grid oscilla-
tions. With massive integration of EVCSs in the coming future,
the consequences arisen from any of the above disruptions
may be far higher than before, potentially leading to cascading
failures and major blackouts in bulk power grids. Hence, the
large EVCSs should run the EV load management and control
algorithm on their own computer or the utility server, while
other data can be uploaded to the public cloud so that the
cloud can only read/store the EVCS data.
EVCSs are allowed to over subscribe the EV charging if the
total load at any time is within the supply system safety limits.
Smart charging considering the EVCS and grid constraints
can be implemented to achieve this and avoid the possible
overload and temperature rise of the transformer connected
to the EVCS (which will otherwise result in an accelerated
transformer loss-of-life). The smart charging assisted by EVCS
communication system can also facilitate the EV load recovery
after interruptions. The interrupted EV load during the outages
can be charged back to the required state of charge (SOC)
as long as the EVSE is able to supply the remaining EV
load demand before the EV departure time. Although the
cold start status—that asks the EVs to start charging within
a random time up to 15 minutes following the interruption—
will not allow a simultaneous charging of the EVs and causes
the transient stability problem in the grid, the uncoordinated
charging still allows all EVs to charge after a short time period
and may violate the grid operation constraints. On the contrary,
smart charging with communication can estimate the EV
load and schedule the charging considering both the transient
stability of the grid and steady-state grid operation constraints.
Hence, the EVCS communication should be supplied by the
backup batteries during the interruption or in the recovery
process before EVs start to charge. Large EVCSs with major
charging power between 26 kW–60 kW, or more than 60 kW
are most suitable for areas where drivers park for less than
half an hour, such as restaurants. These EV loads are usually
regarded as critical loads and may charge during the premium
electricity price period. Distributed generators and storage
units can be used to mitigate the increased peak loads in
such EVCSs and supply the load during the interruption. It is
worth mentioning that continuous supply of some critical EV
loads (such as hospital EV fleet) is very important as failure in
doing so may cause catastrophic consequences. One approach
is to build or increase the capacity of the uninterrupted power
supply system considering the EV loads. Other alternatives
can be to use the plug-in hybrid EV (PHEV) fleet or build the
BSSs which reserve the fully-charged batteries for the fleet
and locate the BSS within short distances.
Note that the safety distance to prevent the EVCS workers
from arc flash hazards should also be considered by the EVCS
operators. The arc flash boundary for the EVCSs with AC
busbar can be calculated by the IEEE Std 1584-2018 [33].
Additional research needs to be done to address the arc flash
boundary for the EVCSs with DC busbar. RF hazards [34]
need to be considered for large EVCSs with the inductive
charging that may be built in the future. To the large BSSs
using robotic arms to swap the EV batteries and automated
factory to mange and charge the batteries, several issues
mentioned earlier (e.g., EVCS cyber-physical system) should
still be complied to ensure an electrically-safe BSS operation.
B. Risk Assessment Metric
A hazard is defined as the potential for harm, and includes
all aspects of technology and activity that produce risk. A risk
is the likelihood that a hazard will cause harm. In response
to the identified hazardous situations for the proposed EVCS
architecture and the corresponding safety considerations, we
here provide a systematic tool to analyze the risk of EVCSs
and take a promising risk control action.
1) Risk of Injury or Health Damages: The risk score Ri
related to an identified hazard is a function of the likelihood
of occurrence of the injury or health damage Poi and the
subsequent impacts and severity Sei of the event i, calculated
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using (1). The total risk score, Rt, which is assessed in (2), is
the sum of the risk scores Ri over all potential risk scenarios.
Ri = Poi × Sei (1)
Rt =
X
i
Ri (2)
Rt includes the risk of exposing customers to dangerous
voltages during the EV charging, and workers to potential
arc flash during the maintenance, etc. It varies with time,
and is affected by the effectiveness of site inspection and
maintenance. While Rt can be used to estimate the total risk
of an EVCS, a heat map of the Ri can be generated with Po
and Se as the two axes in order to prioritize the safety issues
and take additional controls for events with higher Ri. Note
that although the risk score approach is a semi-quantitative
method and could not quantify an accurate risk measure, it
is a widely used risk assessment method to estimate the risk
and can help an effective decision making and risk control to
hazards including, but not limited to, shocks and electrocution,
burns, etc. [35], [36]. The estimated total risk score Rt reflects
the current state of risk for the EVCS, and can be calibrated
by real-world operation data.
2) Risk to Power System Operation: Another risk index is
the energy not supplied factor, ENSF. Firstly, the expected
energy not supplied EENS is calculated using (3) and reflects
the grid reliability status and its ability to continuously serve
the demands. EENS and EENS0
are the sum of the energy
not supplied with and without EVCS during each outage event
j. The contribution of the EVCS to the changes in the EENS
of the system is then assessed via (4).
EENS =
X
j
EENSj (3)
ENSF = α(EENS − EENS0
) (4)
where α indicates the contribution factor of an EVCS to the
EENS, and is calculated as the ratio of the EVCS rated
capacity to the total capacity of EVCSs that contribute to the
interruption. The EV load interruption may not contribute to a
large increase of the EENS if the mobility and flexibility of
the EV load is taken into account and utilized during feeder-
level interruption recovery. Some utility-level interruptions can
also be mitigated when the EVs are charged and ready to
supply the grid several hours earlier than potential disruptions.
Hence, EVCS can contribute to a decrease in EENS. How-
ever, EVCS failure to ride-through and respond to the grid
disturbance may lead to transient stability problem that may
finally affect the system reliability and increase the EENS.
Hence, ENSF is proposed to reflect the risk of the EVCS
cyber and operation layers that contribute to the interruptions.
Approaches on power flow [19] and Monte Carlo Simulation
analysis are typically used to calculate the system EENS.
The state-of-the-art methods could not quantify the impact of
communication system and the flexibility in the EVCS smart
charging on EENS. The cyber-physical system impact of
the EVCS on the grid and computation of EENS need a
co-simulation framework of the cyber-physical power system,
and integrated evaluation of system stability and reliability.
Future work needs to be done to address these research
topics. Here in this paper, we introduce the stability risk index
Sr to qualitatively reflect the risk imposed by the EVCS
cyber layer to the system stability and reliability performance.
Qualitative risk assessment is a simple, yet fast and effective,
approach commonly used when numerical data are inadequate
or unavailable [37]. The risk levels of Sr are here classified
as ’Very low’, ’Low’, ’Medium’, ’High’ and ’Very high’.
C. Discussions on Risk Control
We have discussed several mitigation methods against sev-
eral hazards facing the EVCS operation. Most mitigation
approaches are for the earlier stages in the hierarchy of risk
control and should be considered during the EVCS design
procedures which are less impacted by the supervision per-
formance and human error. However, a large EVCS with
several electrical safety considerations may require sophis-
ticated design and high investments focused on its cyber-
physical system. The EVCS operator may wish to maintain
a certain level of electrical safety at minimum cost. For
example, the EVSEs with safety features are mandatory for all
EVCSs considering that the generality of users has minimum
knowledge on the electricity, but other EVCS designs are
selected based on the EV load characteristics and load demand.
The storage or the uninterrupted power system needs to be
considered when the EVCS supply critical EV load routinely.
Cyber security of EVCSs with high power capacity and with
a DER role to support the grid need to be rigorously checked.
We define the EVCS cost per unit of power ($/kW) as an
index to indicate the economics of the investment:
Cu =
Capital Cost + Operational Cost
Rated Capacity
(5)
Cu reflects the life-cycle cost of the EVCS. As shown in
Fig. 4, the EVCS design and operation need to consider all
indices and do the trade off among all of them (Rt, Sr or Cu)
when necessary. For instance, an EVCS with a few EVSEs can
maintain the basic communication function and use the cloud
to manage the EV charging, as it has little impacts on the
grid. With the same features, a large EVCS with hundreds of
EVSEs will have higher Rt and Sr. However, large EVCS
might simultaneously reduce the three indices when adding
the cyber security enhanced monitoring and control system.
For instance, the predictive maintenance can be done based
on the advanced monitoring system in order to minimize the
risk of load interruption. This in turn may reduce the operation
cost due to reduced inspection frequency and economic losses.
To simplify the process and show the effectiveness of the
proposed risk assessment model, we also use the qualitative
method to represent the Cu values.
IV. NUMERICAL CASE STUDIES
This section compares the performance of the EVCSs with
different designs using the proposed risk assessment model
and the two indices of Rt and Sr. All EVCSs are assumed
to have the total capacity of 1 MW, and the EVSEs in the
EVCS are the same type with the charging capacity of 20
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TABLE I
THE TOTAL RISK SCORE FOR THE EVCS IN CASE 1
Hazard Severity Probability of Occurrence of Harm Risk
Category Po = (Fr + Pr + Av) Score (R)
Se Fr Pr Av Total Se × Po
1 5 5 3 1 9 45
2 7 3 3 3 9 63
3 6 2 2 1 5 30
kW. Hence, the EVCS can use up to 50 EVSEs to charge the
EVs simultaneously. The following four cases are discussed:
• Case 1: An EVCS with no communication and uncoor-
dinated charging.
• Case 2: An EVCS with smart charging using public
communication system, but no grid support as a DER.
• Case 3: An EVCS with smart charging using public
communication, and also working as a DER.
• Case 4: An EVCS with smart charging, also working as
a DER to provide grid support, but using isolated utility
AMI and server to communicate signals.
A. Risk of Injury
A large EVCS may have several situations that can cause
electrical hazards. We classify the electrical hazards into the
following categories: (1) electrical shock to EV customers,
(2) electrical shock and arc flash hazards to workers, and
(3) fire hazard caused by the EV charging that may affect
the personnel’s safety. It is important to note that the electric
shock hazard during charge greatly depends on the electrical
characteristics of the charger (e.g., Class II chargers equipped
with an isolation transformer) [5]. We evaluate the severity
of the possible injury or damage to health Se, and likelihood
of occurrence of such incidents Po in EVCS based on the
risk assessment process criteria of [35]. We assume the EVCS
in Case 1 has the Sei and Poi values as shown in Table I.
Therefore, the total risk score Rt is the summation of Ri for
all hazard categories and equals to 138. The Se values are
similar in all studied cases. The Po includes the frequency
and duration of exposure Fr, the likelihood of occurrence of
a hazardous event Pr and the likelihood of avoiding or limiting
injury or damage to health Av. The Fr and Av values will
also be similar in different cases where EVCSs have similar
number of customers and physical facilities. With the enhanced
cyber layer in EVCS, the Pr decreases. The Pr with a value
of 3 indicates that a hazardous event is likely to happen, the
Pr with a value of 2 means the hazard has a rare chance
to happen and Pr value of 1 means a negligible possibility
of the hazard. We assume the EVCS in Case 2 and Case 3
will decrease the Pr values of three hazard categories to 2,
2, and 1, respectively. And the EVCS in Case 4 with further
considerations of cyber reliability and security will decrease
the Pr value to 1, 1, and 1, respectively. The Rt in all cases
are shown in Table II.
635
Fig. 5. The modified IEEE 13-node test feeder.
Fig. 6. Low voltage ride through of the EVCS.
B. Impacts on Power Grid Stability and Reliability
We assume that the EVCSs oversubscribe 20 EVSEs for
Case 2 to 4 so that the individual EV customer behavior
has a little impact on the EVCS charging capacity. We also
assume the EVCSs as DERs in the grid in Case 3 and Case 4,
following the grid code of IEEE 1547-2018. The DER ride-
through priority and mode selection is based on Fig 3. The
voltage-reactive power setting of the EVCS follow the default
setting of the Category B DER requirement and the response
time is set to 1s. The frequency-droop operation of the EVCS
during an abnormal conditions in the Area EPS follows the
Category III DER requirements, the frequency dead-band is
set to 0.2 Hz, and the response time is set to 0.2s.
The IEEE 13-node test feeder [38] is modified to test the
interconnection impact of the EVCS to the the grid, the one-
line diagram of which is shown in Fig. 5. The original load
keeps the same and the total load is 3.58 MW. We assume
there are 3 same EVCSs with the rated power of 1 MW at
node 635. So, the aggregated EVCS capacity is 3 MW. The
PV system is also located at node 635 with the capacity of
4 MW and the maximum power point tracking technology
with the power factor of 1. We assume a steady-state initial
operation of the feeder during a typical summer day, when
the EVCSs are charging the EVs with 0.2 MW, and the PV
output is 2.17 MW. The nominal line-to-line voltage rating of
the feeder is 4160V and the grid supply 1.01 per unit at node
632. The Matlab/Simulink software package is used to run the
electromagnetic transient (EMT) simulations and illustrate the
EVCS response as DERs. The simulation step is 2.5 × 10−7
s.
Three-phase programmable voltage source is used as the
grid supply at node 632 to generate the voltage event, where
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0 5 10 15
time (s)
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
Node
Voltage
(p.u.) Node 635 voltage with reactive power injection of EVCS
Node 635 voltage without reactive power injection of EVCS
Node 632 voltage
Fig. 7. Comparisons of the EVCSs voltage response during the transients.
1 2 3 4 5 6 7 8 9 10
time (s)
a
59.2
59.4
59.6
59.8
60
Frequency
(Hz)
1 2 3 4 5 6 7 8 9 10
time (s)
b
-200
-100
0
100
200
300
Power
(kW)
Fig. 8. Frequency response performance. (a) Frequency of the grid, (b)
Frequency response of the EVCS.
the EVCSs operate under the voltage-reactive power mode.
The EVCS voltage curve is shown in Fig. 6. The EVCS can
ride through the voltage event and avoid a trip if its design
allows for a May Ride Through ranges of grid voltage. Hence,
the EVCSs should be designed and built to withstand speci-
fied abnormal conditions and support the grid stability and
reliability while still protecting the equipment from damage
and ensuring personnel safety. Fig. 7 shows different voltage
responses during the voltage event. Compared with the grid
voltage at node 632, the voltage at node 635 without reactive
power injection of EVCS but with PV power output, is higher
in Case 2. The voltage at node 635 with reactive power
injection of EVCS and PV power output in Case 3 and Case 4
is higher than both voltage curves after the required voltage-
reactive power response time. This is because the R and X
values of distribution overhead lines in the medium voltage
distribution network are similar, where an increase in both
nodal active and reactive power will increase the voltage. The
reactive power injection to the grid during the low voltage
event will bring more benefits when there are induction loads
such as air conditioners. However, the EVCSs in Case 3
employing public communication system to select the control
mode and monitor the station is more vulnerable than that in
Case 4 due to potential communication delays and failures.
A frequency event is also generated by the grid supply at
node 632 to test the frequency response of the EVSEs. The
grid frequency drops starting from 60 Hz at 1 s to 59.3 Hz
and then recovers back, as illustrated in Fig. 8a. The EVCS
TABLE II
INDEX COMPARISONS IN DIFFERENT CASE STUDIES
TC Rt Sr Cu
1 138 high low to medium
2 120 high medium
3 120 medium medium
4 108 low medium to high
responses to the frequency event after 0.2s when the grid
frequency reaches its low-frequency dead-band of 59.8 Hz.
It can be seen in Fig. 8b that instead of charging 0.2 MW
before the frequency event, the EVCS reduces the charging
power and starts to supply power to the grid when the grid
frequency declines. Different from the controllable reactive
power output that can provide local voltage support, the active
power output of all resources can impact the system frequency
and wide-area system stability [39]. EVCS frequency support
with the frequency-droop design in Case 3 and 4 will be
more beneficial when the number of EVCSs in the system
increases, and is highly effective when the system integrates
more intermittent renewable sources such as solar and wind.
However, the EVCSs frequency support in Case 3 is more
vulnerable to the communication delay and malfunctions as
the EV power schedule is managed by the public cloud. In
case of successful information acquisition and a cyber attack
to public network or cloud, the bulk power system safety
is threatened and system wide blackout may happen due to
inability to preserve the system stability thresholds.
Based on the above analysis, the EVCS in Case 2 has
higher stability risk due to the cyber vulnerability. The EVCS
in Case 3 has ’medium’ Sr value as the EVCS can ride-
through the gird disturbance when no cyber hazard occurs.
The EVCS in Case 4 has ’low’ Sr value as the cyber attack
probability is low. The EVCS without communication with the
utility and cloud in Case 1 will not be affected by the cyber
system performance, but the uncoordinated charging increases
the chance that the grid operates near marginal conditions,
thereby the Sr value is ’high’. The Sr values for all cases are
also included in Table II.
C. Comparisons
As the EVCS in all four test cases use the same facil-
ities in the physical layer, the EVCS in Case 1 has little
investment cost for cyber layer and the Cu is ’low’. The
Cu values for EVCS using public communication system in
Case 2 and 3 are ’medium’. The Cu value for EVCSs using
isolated communication system is ’high’ considering the extra
investments in the communication system. However, the EVCS
using uncoordinated charging in Case 1 may not do the EVSE
over-subscription and require transformer and distribution line
upgrades with a higher operation cost. So the Cu value in
Case 1 may increase. The Cu value for the EVCS using the
isolated communication system may decrease if the utility
has built the AMI with isolated communication system for
gird modernization. As can be seen in Table II, the EVCS
configuration in Case 4 has the lowest risk. Although the
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isolated communication system for EVCSs in Case 4 needs
extra investment, it may be preferred by the utilities.
V. CONCLUSION
This paper discussed several safety considerations around
large EVCS. In order to ensure a safe operation environment
of the EVCSs, they need to not only follow the safety re-
quirements for EVSEs [4], but also comply with other existing
standards and guidelines such as the arc flash boundary [33],
grid interoperability [27], periodic inspection [6], fire safety
[7], and maintenance related to the EVCS facilities discussed
in National Fire Protection Association (NFPA) 70B and
Canadian Standards Association (CSA) Z463 [40] etc. We
have also analyzed the safety considerations of the proposed
EVCS cyber-physical system in different layers. Furthermore,
a risk assessment model for large EVCSs is proposed, enabling
the EVCS operators to evaluate the electrical safety using the
hierarchy of hazard control methods. Numerical case studies
demonstrated that the risk assessment model for EVCSs can
effectively evaluate the safety considerations of large EVCSs
and help informative planning and operation decisions.
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Bo Wang received the B.Sc. degree in automa-
tion from Jilin University, Changchun, China, in
2013, and the M.Sc. degree in Electrical Power and
Energy from The George Washington University,
Washington D.C., USA, in 2015. He is currently
pursuing the Ph.D. degree at the Department of
Electrical and Computer Engineering, The George
Washington University, Washington, D.C., USA. His
research interests include electric vehicles, power
system optimization and control, and power system
reliability.
Payman Dehghanian (S11, M17) is an Assistant
Professor at the Department of Electrical and Com-
puter Engineering in George Washington University,
Washington, D.C., USA. He received the B.Sc.,
M.Sc., and Ph.D. degrees all in Electrical Engineer-
ing respectively from University of Tehran, Tehran,
Iran, in 2009, Sharif University of Technology,
Tehran, Iran, in 2011, and Texas A&M University,
Texas, USA in 2017. His research interests include
power system protection and control, power system
reliability and resiliency, asset management, and
smart electricity grid applications.
Dr. Dehghanian is the recipient of the 2013 IEEE Iran Section Best M.Sc.
Thesis Award in Electrical Engineering, the 2014 and 2015 IEEE Region
5 Outstanding Professional Achievement Awards, and the 2015 IEEE-HKN
Outstanding Young Professional Award.
Shiyuan Wang received the B.Eng degree in me-
chanical engineering from University of Science
and Technology Beijing, China, in 2012; the M.Sc.
degree in electrical engineering from The George
Washington University, Washington, DC., USA, in
2014. He is currently pursuing the Ph.D. degree at
the Department of Electrical and Computer Engi-
neering, George Washington University, Washing-
ton, D.C., USA. His research interests include power
system reliability and resiliency, smart grid and
renewable energy, power grid harmonic analysis, and
application of signal processing in energy analytics.
Massimo Mitolo (SM03) received the Ph.D. in
Electrical Engineering from the University of Napoli
Federico II, Italy, in 1990. Dr. Mitolo is currently a
Full Professor of Electrical Engineering at the Irvine
Valley College, Irvine, CA, USA, and a Senior Con-
sultant in electric power engineering with Engineer-
ing Systems Inc., ESi. Dr. Mitolo has authored over
118 journal papers and the books Electrical Safety
of Low-Voltage Systems (McGraw-Hill, 2009) and
Laboratory Manual for Introduction to Electronics:
A Basic Approach (Pearson, 2013). His research
interests include the analysis and grounding of power systems, and electrical
safety engineering.
Dr. Mitolo is a registered Professional Engineer in the state of California and
in Italy. He is currently the deputy Editor-in-Chief of the IEEE Transactions
on Industry Applications. He is active within the Industrial and Commercial
Power Systems Department of the IEEE Industry Applications Society (IAS)
in numerous committees and working groups. He also serves as an Associate
Editor for the IEEE IAS Transactions. Dr. Mitolo has received numerous
recognitions and best paper awards, among which are the IEEE-I&CPS Ralph
H. Lee Department Prize Paper Award, the IEEE-I&CPS 2015 Department
Achievement Award, and the IEEE Region 6 Outstanding Engineer Award.