A high penetration of electric vehicle (EV) charging in low voltage (LV) networks can challenge grid stability due to voltage variations and limited feeder capacity. This research paper examines the ...integration of electric vehicle (EV) charging in real-life residential low voltage (LV) networks in Malta. The study utilizes smart metering data and presents a methodology framework and tools to analyze the impacts of EV charging on grid stability. The likelihood of challenges in the LV network is assessed by conducting simulations and deriving cumulative distribution functions (CDFs). The study also evaluates the impact of EV charging on the occurrence of network challenges and identifies predominant issues through multi-feeder analyses. Additionally, a regression analysis tool is developed to predict the impacts based on feeder characteristics. The results show strong relationships between feeder characteristics and EV charging processes, offering valuable insights for network planning and operations. However, it should be noted that the current EV charging penetration in the Maltese grid is below 1% in any LV feeder, suggesting the absence of significant technological hurdles at present.
High Photovoltaic (PV) and Electric Vehicle (EV) Charging Penetration challenges the grid’s Low-Voltage (LV) Distribution Network’s stability due to voltage variations and the overloading of feeders. ...This research paper investigates the potential of combined PV and Electric Vehicle (EV) charging integration within LV DN, using a representative DN in Malta as a case study. The European Union (EU) has set forth objectives and guidelines that suggest a high likelihood of Distributed Networks (DNs) incorporating a significant number of Photovoltaic Systems (PVs), resulting in overvoltage occurrences, as well as a substantial number of Electric Vehicles (EVs), which may charge in an erratic manner, leading to undervoltage and overloading events. A distribution network (DN) may experience unfavorable situations concurrently due to the simultaneous occurrence of photovoltaic (PV) generation and electric vehicle (EV) charging, particularly in residential case studies. Effectively employing either dispersed or centralized storage is a viable approach to tackle these issues. However, this strategy may defer the requirement for expensive DN investments. The study showcases the extent of automated mitigation attained in the urban zones of Malta. The data presented primarily comprises empirical measurements obtained at the onset of the LV feeder.
Malta faces a significant challenge in reducing carbon emissions, with energy consumption in its 153,100 occupied residences contributing to 30% of CO2 emissions. This study focuses on a sample of an ...1870s, 80 sq-m footprint, three-story residence, emblematic of similar properties facing marketability issues due to age, structure, and maintenance. The objective is to assess a techno-economic energy and CO2 abatement framework, including advanced lighting devices, appliances, photovoltaics, wind turbines, energy storage, and vehicle-to-grid possibilities. The research evaluates comfortability and calculates potential 25-year kWh reduction and cost savings for each measure. The findings demonstrate the feasibility of implementing diversified renewable and alternative energy sources in such residences. Over 25 years, approximately 250 MWh of energy could be mitigated, leading to a reduction of approximately 140 metric tons of carbon dioxide. The study emphasizes the importance of housing stock efficiency in both new construction and retrofitting, focusing on building performance for health, comfort, and living standards. While most systems are viable, further research is needed for system-wide strategy implementation, particularly in areas like energy storage and wind turbine solutions. The study concludes that adopting emerging technologies could be advantageous in minimizing system costs through innovative building-integrated designs.
Photovoltaic systems (PVs) are promising low-carbon technologies playing a major role in the electricity business. In terms of voltage variation and feeder usage capacity, high PV penetration levels ...have significant technical implications for grid stability, particularly in Low Voltage (LV) networks. This paper presents a comprehensive PV integration analysis on real-life residential LV networks in Malta using recorded smart metering data. The methodology framework and tools developed are highlighted through step-by-step results on their usefulness. First, at the substation level, an LV network with seven LV feeders is analyzed using Monte Carlo simulations and OpenDSS. Then, Cumulative Distribution Functions (CDFs) are extracted to establish the likelihood of LV network challenges. Afterwards, 95 multi-feeder analyses assess the impact assessment on the first occurrence of LV network challenges and predominant issues. Finally, a Regression Analysis Tool, considering the regression’s standard error, is built for seven feeder characteristics to predict the impacts. The stochastic processes reveal strong relationships with feeder characteristics that are helpful for network planning and operations. However, the Maltese grid currently has less than 20% PV penetration at any LV feeder. Hence, significant technological hurdles are absent.
Electric vehicles (EVs) have been garnering wide attention over conventional fossil fuel-based vehicles due to the serious concerns of environmental pollution and crude oil depletion. In this ...article, we have conducted a systematic literature survey to explore the battery raw material supply chain, material processing, and the economy behind the commodity price appreciation. We present significant areas of concern, including resource reserves, supply, demand, geographical distribution, battery reuse, and recycling industries. Furthermore, details of the battery supply chain and its associated steps are illustrated. The authors believe the presented study will be an information cornerstone in boosting manufacturing and understanding the key components and materials required to facilitate EV battery production. Further, this study discusses the major industries, and their policies and global market share in each material category.
Due to the high penetration of grid-connected photovoltaic (GCPV) systems, the network operators are regularly updating the grid codes to ensure that the operation of GCPV systems will assist in ...maintaining grid stability. Among these, low-voltage-ride-through (LVRT) is an essential attribute of PV inverters that allows them to remain connected with the grid during short-term disturbances in the grid voltage. Hence, PV inverters are equipped with control strategies that secure their smooth operation through this ride-through period as per the specified grid code. However, during the injection of reactive power under LVRT condition, various challenges have been observed, such as inverter overcurrent, unbalance phase voltages at the point of common coupling (PCC), overvoltage in healthy phases, oscillations in active, reactive power and dc-link voltage, distortion in injected currents and poor dynamic response of the system. Several strategies are found in the literature to overcome these challenges associated with LVRT. This paper critically reviews the recent challenges and the associated strategies under LVRT conditions in GCPV inverters. The drawbacks associated with the conventional current control strategies are investigated in MATLAB/Simulink environment. The advanced LVRT control strategies are categorized and analyzed under different types of grid faults. The work categorizes the state-of-the-art LVRT techniques on the basis of the synchronization methods, current injection techniques and dc-link voltage control strategies. It is found that state-of-the-art control strategies like OVSS/OCCIDGS provides improved voltage support and current limitation, which results in smooth LVRT operation by injecting currents of enhanced power quality.
The primary driver for development of organic photovoltaic (OPV) technologies is the prospect of very low cost module manufacture leading to affordable solar electricity. This paper presents an ...economic assessment of OPV based on an existing pre-industrial manufacturing process and the associated detailed material inventory. Using life cycle costing techniques, the life cycle investment cost for a 1kWp, grid-connected OPV system is calculated, taking into account the materials, direct process energy, labour, balance of system components, design and maintenance costs. Assuming values for the performance ratio of the PV system, insolation level, inflation and interest rates, the levelised electricity cost (LEC) is calculated. Under an average solar irradiance of 1700 kWh/m2/year, typical of southern Europe, a LEC of between 0.19 euro sign/kWh and 0.50 euro sign/kWh was calculated for a 1kWp system, based on modules containing 7% efficient cells and assuming a 5 year module lifetime. The OPV module is found to make up the majority of the system cost while the material costs constitute the largest contribution to the cost of the OPV module. The influence of OPV module lifetime is studied using sensitivity. This paper demonstrates that competitive solar electricity from OPV is within reach if efficiencies of ca. 7% already demonstrated in lab scale devices can be achieved in large area modules and if lifetimes of at least 5 years can be achieved.
This paper presents a power quality analysis for multiple electric vehicle charging stations of the AC-Level 2 type in a real-life case study. The data was collected with a power quality analyzer ...that measured the main distribution system feeding nine 7 kW charging stations in a commercial site with light-duty vehicles in Malta, Europe. The relevance of this study to the specific case of Malta is accentuated by the topological challenges of the country; high density of road vehicles, with 18,000 vehicles for each square kilometer; and ambitious targets of reaching carbon neutrality by 2050. Data were collected over six days on an actual charging system with real-life charging patterns. Various results are presented in this paper, including three-phase system voltages and currents, individual harmonic voltage and current components, total harmonic distortion and total current demand distortion. These measurements were compared with standardized thresholds for low-voltage equipment used in public spaces, mainly as stated in IEEE 519-2014.
In this paper, a new hybrid TSA-PSO algorithm is proposed that combines tunicate swarm algorithm (TSA) with the particle swarm optimization (PSO) technique for efficient maximum power extraction from ...a photovoltaic (PV) system subjected to partial shading conditions (PSCs). The performance of the proposed algorithm was enhanced by incorporating the PSO algorithm, which improves the exploitation capability of TSA. The response of the proposed TSA-PSO-based MPPT was investigated by performing a detailed comparative study with other recently published MPPT algorithms, such as tunicate swarm algorithm (TSA), particle swarm optimization (PSO), grey wolf optimization (GWO), flower pollination algorithm (FPA), and perturb and observe (P&O). A quantitative and qualitative analysis was carried out based on three distinct partial shading conditions. It was observed that the proposed TSA-PSO technique had remarkable success in locating the maximum power point and had quick convergence at the global maximum power point. The presented TSA-PSO MPPT algorithm achieved a PV tracking efficiency of 97.64%. Furthermore, two nonparametric tests, Friedman ranking and Wilcoxon rank-sum, were also employed to validate the effectiveness of the proposed TSA-PSO MPPT method.
Light-Duty Electric Vehicle (LDEV) with a distributed drive powertrain provides several potential advantages in terms of flexibility, controllability and responsiveness over conventional powertrains. ...The precise distribution of driving and braking torque of such configuration is crucially vital for improving the overall performance and efficiency of the vehicles. This paper proposes a new torque allocation (TA) model emphasizing the wheel load variation due to the passenger occupancy payload. A light-duty vehicle model is developed along with the occupancy payload arrangement and a dynamic tire-road friction estimation method for the control system for wheel slip. This proposed TA algorithm uses offline optimization to derive the necessary transmissible torque to the driving wheels. Unlike conventional optimization, it adopts a set of predefined distribution coefficients. Therefore it can execute in a real time platform without high computation power and additional hardware requirements. The efficiency of the model is analyzed using Indian Urban Drive Cycle (IN-UDC). A comparative analysis using a traditional torque allocation model highlights the contributions of this novel torque allocation. The results obtained from various simulations demonstrate the effectiveness of the proposed new TA algorithm.
PDF
