Search Results (61)

The European Union’s 2030 target of decreasing net greenhouse gas emissions by at least 55% has resulted in a significant uptake of renewable energy sources (RESs) in the European power system, primarily wind and solar power, as well as the closure of conventional power plants that mostly used fossil fuels. The European Union’s members have accelerated the process of energy transition driven by climate change, and public authorities’ involvement in this process is impressive. The goal of this study is to present a broad overview of the existing challenges for the energy transition in Europe and how they can affect the reliability and stability of the interconnected power system in Europe and future investments, focusing especially on Greece. Unfortunately, this environmentally friendly transition is taking place without the required amount of investment in electrical energy storage technology, which raises the risk of a blackout due to the high predicted variability of RES. The gradual abandonment of conventional energy production units such as natural gas in the coming decades will intensify the problem of frequency regulation, which will become even more acute due to the particularly increased installed capacity in RESs across Europe and Greece. The European Power System, being partially unprepared for the energy transition, frequently faces a paradox: it rejects green power originating from high-RES production because of low demand, a lack of transmission line interconnections, or extremely low energy storage capacity. This paper examines all the prerequisites, including how the European electrical transmission system will be developed in the future and how new energy storage technologies will be used. Lastly, Greece’s energy future and potential risks associated with realizing the environmental goals of the European Green Deal is studied using a PESTEL analysis. Full article

With its unique environment and strategic value, the near space (NS) has become the focus of global scientific and technological, military, and commercial fields. Aiming at the problem of communication interruption when the aircraft re-enters the atmosphere, to ensure the needs of communication, navigation, and telemetry, tracking, and command (TT&C), this paper proposes an overall integration of communication, navigation, and TT&C (ICNT) signals scheme based on the K/Ka frequency band. Firstly, the K/Ka frequency band is selected according to the ITU frequency division, high-speed communication requirements, advantages of space-based over-the-horizon relay, overcoming the blackout problem, and the development trend of high frequencies. Secondly, the influence of the physical characteristics of the NS on ICNT is analyzed through simulation. The results show that when the K/Ka signal is transmitted in the NS, the path loss changes significantly with the elevation angle. The bottom layer loss at an elevation angle of 90° is between 143.5 and 150.5 dB, and the top layer loss is between 157.5 and 164.4 dB; the maximum attenuation of the bottom layer and the top layer at an elevation angle of 0° is close to 180 dB and 187 dB, respectively. In terms of rainfall attenuation, when a 30 GHz signal passes through a 100 km rain area under moderate rain conditions, the horizontal and vertical polarization losses reach 225 dB and 185 dB, respectively, and the rainfall attenuation increases with the increase in frequency. For gas absorption, the loss of water vapor is higher than that of oxygen molecules; when a 30 GHz signal is transmitted for 100 km, the loss of water vapor is 17 dB, while that of oxygen is 2 dB. The loss of clouds and fog is relatively small, less than 1 dB. Increasing the frequency and the antenna elevation angle can reduce the atmospheric scintillation. In addition, factors such as the plasma sheath and multipath also affect the signal propagation. In terms of modulation technology, the constant envelope signal shows an advantage in spectral efficiency; the new integrated signal obtained by integrating communication, navigation, and TT&C signals into a single K/Ka frequency point has excellent characteristics in the simulation of power spectral density (PSD) and autocorrelation function (ACF), verifying the feasibility of the scheme. The proposed ICNT scheme is expected to provide an innovative solution example for the communication, navigation, and TT&C requirements of NS vehicles during the re-entry phase. Full article

Aiming at the problems of significant communication overheads, the low reliability of primary nodes, and the insufficient dynamic adaptability of traditional consensus algorithms in intellectual property transaction scenarios, an Improved Practical Byzantine Fault Tolerant (IPBFT) algorithm based on the Chord algorithm and entropy weight method is proposed. Firstly, the Chord algorithm is employed to map nodes onto a hash ring, enabling dynamic grouping. Secondly, an entropy-based dynamic reputation model is constructed, quantifying the evaluation of node behaviors and calculating the overall reputation value. A three-level reputation classification mechanism is used to dynamically select primary and supervisory nodes, thereby reducing the probability of Byzantine nodes being elected. Then, a three-phase monitoring strategy for supervisory nodes is developed, which includes collection, review, and blackout. This improves the Raft consensus process, enhancing the detection and fault tolerance against malicious leaders. Finally, a grouped dual-layer consensus architecture is proposed. The lower layer uses an improved Raft algorithm for efficient consensus within groups, while the upper layer uses the PBFT algorithm for cross-group global consistency verification. Experimental findings demonstrate that the IPBFT algorithm is able to balance security, scalability, and consensus efficiency in a dynamic network environment, providing a better consensus solution for intellectual property transactions. Full article

With the increasing complexity of the distribution network structure, enhancing the efficiency and reliability during fault restoration has become a focal point. Based on the multi-source information collected by traditional sensors, such as CT and PT, and intelligent sensors, such as D-PMU, and the graph calculation model, the fault recovery problem of a multi-objective distribution network is studied. Firstly, a power flow calculation model and operation constraint adaptable to topology changes are proposed under the graph calculation framework. The minimum spanning tree theory is utilized to define the blackout range and recovery path set. Secondly, the intelligent sensor D-PMU is configured to collect fault information to ensure that at least one of any two connected load vertices is configured with D-PMU. Thirdly, a topological evolution model is established that considers repeated primary and secondary transfer in outage areas while exploring possible recovery strategies deeply. Finally, a distribution network in Shaanxi Province is taken as an example to verify the model. The experiment shows that the strategy in this paper dynamically adjusts the recovery strategy through four means—one transfer, one repeat transfer in the outage area, two transfers, and cutting off part of the outage load—and the overall recovery rate is increased by more than 20%. Full article

Power systems are naturally prone to numerous uncertainties. Power system functioning is inherently unpredictable, which makes the networks susceptible to instability. Rotor-angle instability is a critical problem that, if not effectively resolved, may result in a series of failures and perhaps cause blackouts (collapse). The issue of state feedback sliding mode control (SMC) for the excitation system is addressed in this work. Control is decentralized by splitting the global system into several subsystems. The effect of the rest of the system on a particular subsystem is considered a disturbance. The next step is to build the state feedback controller with the disturbance attenuation level in mind to guarantee the asymptotic stability of the closed-loop system. The algorithm for SMC design is introduced. It is predicated on choosing the sliding surface correctly using the invariant ellipsoid approach. According to the control architecture, the system motion in the sliding mode is guaranteed to only be minorly affected by mismatched disturbances in power systems. Furthermore, the proposed controllers are expressed in terms of Linear Matrix Inequalities (LMIs) using the Lyapunov theory. Lastly, an IEEE test system is used to illustrate how successful the suggested approach is. Full article

South Africa has been experiencing an energy crisis since 2007 and continues to the present. This has resulted in load-shedding (action to interrupt electricity supply to avoid excessive load on the generating plant). One way to address this problem is to further explore the potential and contribution of bioenergy through research conducted and implementing energy reports. Therefore, the study aims to provide the state of bioenergy and its contribution to the country’s economic sector and to enhance the replacement of fossil fuels with bioenergy resources and technology. A total blackout of 15,913 h has been experienced since 2014, according to the weekly system status report released by ESKOM. The power utility (Eskom) responsible for power generation and utility has attributed this problem to insufficient generation and capacity. Based on this, the country is embarking on solving this problem. Although the country is dominated by coal (fossil fuel), constituting 73.8% of the total energy supply, this poses a serious environmental risk and health hazard. Renewable energy is considered an alternative energy source, and its introduction and implementation look promising in reducing and solving the current energy crisis. With abundant renewable energy potential, representing 8.7% of the total energy supply, around 85% is bioenergy. This review’s findings revealed that bioenergy contributed mainly towards heat, and fuels admit other energy sources, which is recommended. Therefore, its deployment on a large scale is promising and possible. This study will guide and further encourage the deployment of bioenergy projects in South Africa. Full article

Global warming increases the risk of power outages. Mine water pumping stations pump approximately 100 million m³ of water per year (2023). The cessation of mine water pumping would expose neighboring mines and lower lying areas to flooding. The pumping stations have some containment, but a prolonged shutdown could cause environmental problems. Remediation of the resulting damage would be costly and time-consuming. The combination of the problems of dewatering abandoned mines and storing energy in the form of hydrogen to ensure continuity of power supply to pumping stations has not been the subject of extensive scientific research. The purpose of this paper was to develop options for protecting mine water pumping stations against the “blackout” phenomenon and to assess their investment relevance. Six technically feasible options for the modernization of mine water pumping stations were designed and analyzed in the study. All pumping station modernization options include storage of the generated energy in the form of green hydrogen. For Q1 2024 conditions, the option with the partial retail sale of the produced hydrogen and the increased volume of produced water for treatment is recommended for implementation. Full article

In the Industry 4.0 era of smart grids, the real-world problem of blackouts and cascading failures due to cyberattacks is a significant concern and highly challenging because the existing Intrusion Detection System (IDS) falls behind in handling missing rates, response times, and detection accuracy. Addressing this problem with an early attack detection mechanism with a reduced missing rate and decreased response time is critical. The development of an Intelligent IDS is vital to the mission-critical infrastructure of a smart grid to prevent physical sabotage and processing downtime. This paper aims to develop a robust Anomaly-based IDS using a statistical approach with a machine learning classifier to discriminate cyberattacks from natural faults and man-made events to avoid blackouts and cascading failures. The novel mechanism of a statistical approach with a machine learning (SAML) classifier based on Neighborhood Component Analysis, ExtraTrees, and AdaBoost for feature extraction, bagging, and boosting, respectively, is proposed with optimal hyperparameter tuning for the early discrimination of cyberattacks from natural faults and man-made events. The proposed model is tested using the publicly available Industrial Control Systems Cyber Attack Power System (Triple Class) dataset with a three-bus/two-line transmission system from Mississippi State University and Oak Ridge National Laboratory. Furthermore, the proposed model is evaluated for scalability and generalization using the publicly accessible IEEE 14-bus and 57-bus system datasets of False Data Injection (FDI) attacks. The test results achieved higher detection accuracy, lower missing rates, decreased false alarm rates, and reduced response time compared to the existing approaches. Full article

A grid blackout is an intractable problem with serious economic consequences in many developing countries. Although it has been proven that microgrids (MGs) are capable of solving this problem, the uncertainties regarding when and for how long blackouts occur lead to extreme difficulties in the design and operation of the related MGs. This paper addresses the optimal design problem of the MGs considering the uncertainties of the blackout starting time and duration utilizing the kernel density estimator method. Additionally, uncertainties in solar irradiance and ambient temperature are also considered. For that, chance-constrained optimization is employed to design residential and industrial PV-based MGs. The proposed approach aims to minimize the expected value of the levelized cost of energy ($LCOE$), where the restriction of the annual total loss of power supply ($TLPS$) is addressed as a chance constraint. The results show that blackout uncertainties have a considerable effect on calculating the size of the MG’s components, especially the battery bank size. Additionally, it is proven that considering the uncertainties of the input parameters leads to an accurate estimation for the LCOE and increases the MG reliability level. Full article

This paper introduces a groundbreaking approach to demand response management, aiming to empower consumers through innovative strategies. The key contribution is the concept of “acquiring flexibility rights”, wherein consumers engage with power aggregators to curtail energy usage during peak-load periods, receiving incentives in return. A flexibility right coefficient is introduced, allowing consumers to tailor their participation in demand response programs, ensuring their well-being. Additionally, a lighting intensity control system is developed to enhance residential lighting network efficiency. The study demonstrates that high-energy consumers, adopting a satisfaction factor of 10, can achieve over 61% in electricity cost savings by combining the lighting control system and active participation in demand response programs. This not only reduces expenses but also generates income through the sale of flexibility rights. Conversely, low-energy consumers can fully offset their expenses and accumulate over USD 33 in earnings through the installation of solar panels. This paper formulates an optimization problem considering flexibility rights, lighting control, and time-of-use tariff rates. An algorithm is proposed for a distributed solution, and a sensitivity analysis is conducted for evaluation. The proposed method showcases significant benefits, including cost savings and income generation for consumers, while contributing to grid stability and reduced blackout occurrences. Real data from a residential district in Tehran validates the method’s effectiveness. This study concludes that this approach holds promise for demand response management in smart grids, emphasizing the importance of consumer empowerment and sustainable energy practices. Full article

Public works environmental disasters such as the Flint water crisis typically occur in disenfranchised communities with municipal disinvestment and co-occurring risks for poor mental health (poverty, social disconnection). We evaluated the long-term interplay of the crisis and these factors with substance use difficulties five years after the crisis onset. A household probability sample of 1970 adults living in Flint during the crisis was surveyed about their crisis experiences, use of substances since the crisis, and risk/resilience factors, including prior potentially traumatic event exposure and current social support. Analyses were weighted to produce population-representative estimates. Of the survey respondents, 17.0% reported that substance use since the crisis contributed to problems with their home, work, or social lives, including 11.2% who used despite a doctor’s warnings that it would harm their health, 12.3% who used while working or going to school, and 10.7% who experienced blackouts after heavy use. A total of 61.6% of respondents reported using alcohol since the crisis, 32.4% using cannabis, and 5.2% using heroin, methamphetamine, or non-prescribed prescription opioids. Respondents who believed that exposure to contaminated water harmed their physical health were more likely to use substances to the detriment of their daily lives (RR = 1.32, 95%CI: 1.03–1.70), as were respondents with prior potentially traumatic exposure (RR = 2.99, 95%CI: 1.90–4.71), low social support (RR = 1.94, 95%CI: 1.41–2.66), and PTSD and depression (RR’s of 1.78 and 1.49, respectively, p-values < 0.01). Public works disasters occurring in disenfranchised communities may have complex, long-term associations with substance use difficulties. Full article

A plasma sheath will be developed surrounding a hypersonic vehicle in flight, which can reflect, absorb, and scatter electromagnetic (EM) waves of lower frequencies than its own, resulting in a communication blackout. This paper focuses on knowing how to limit the absorption and reflection of low-frequency EM waves by plasma sheath in a thermodynamic and chemical non-equilibrium state. According to the temperature increment model, the energy of high-power microwave (HPM) irradiation is translated into the temperature increment of heavy particles in plasma. As a result of this modification process, the transmittance of low-frequency EM waves going through the plasma sheath in a certain time frame rises, potentially easing the communication blackout problem. Full article

The increasing demand for electricity has put a strain on existing power transmission and distribution systems. As a result, utilities are often forced to overload their existing systems, which can lead to voltage instability, transmission line congestion, and even blackouts. To fix these problems, flexible AC transmission system controllers (FACTs) can be used. This paper deals with two objectives: minimizing voltage deviation and real power losses, and the minimization has been performed using the multi-objective artificial bee colony algorithm (MOABC). UPFC has been optimally placed on the IEEE bus-39 system. The proposed work is implemented through MATLAB coding. Full article

Due to the demand for eco-friendly energy, distributed energy resources (DERs) using renewable energy have increased. The increase in DER has caused the power system to become more complex and caused problems in the protection system. Typical problems include an increase in fault current and a problem that causes malfunction of the overcurrent relay (OCR). If the fault current increases and exceeds the capacity of the existing protection devices, it may lead to a large blackout. The most effective way to limit the fault current is to install a superconducting current limiter (SFCL). The installation of SFCL and system penetration of DER both affect OCR operating characteristics. In this paper, a simulated power distribution system is constructed and OCR malfunctions caused by DER penetration and SFCL installation are analyzed. Full article

A high-temperature plasma sheath is generated on the surface of the re-entry vehicle through the conversion of kinetic energy to thermal and chemical energy across a strong shock wave at the hypersonic speed. Such a condition results in the forming of a blackout which significantly affects the communication components. To analyze the re-entry vehicle at the hypersonic speed, an unconditionally stable system incorporated factorization-splitting (SIFS) algorithm is proposed in finite-difference time-domain (FDTD) grids. The proposed algorithm shows advantages in the entire performance by simplifying the update implementation in multi-scale problems. The plasma sheath is analyzed based on the modified auxiliary difference equation (ADE) method according to the integer time step scheme in the unconditionally stable algorithm. Higher order perfectly matched layer (PML) formulation is modified to simulate open region problems. Numerical examples are carried out to demonstrate the performance of the algorithm from the aspects of target characteristics and antenna model. From resultants, it can be concluded that the proposed algorithm shows considerable accuracy, efficiency, and absorption during the simulation. Meanwhile, plasma sheath significantly affects the communication and detection of the re-entry vehicle. Full article