Hasil untuk "Distribution or transmission of electric power"

T. Adefarati, R. Bansal

Xindong Liu, M. Shahidehpour, Zuyi Li et al.

Ruifeng Zhao, Zufeng Hou, Jiangang Lu et al.

B. Uzum, Y. Yoldas, S. Bahceci et al.

Muneki Masuda, Hayato Satoh

Japan aims to achieve carbon neutrality by 2050, with a target of 100% sale of electric vehicles (EVs) by 2035. An increase in EV charging demand changes the characteristics of load demand and in turn, affects power system stability. Therefore, a load model that considers EV charger characteristics is required. We had developed and verified an EV charger model through a root mean square analysis following balanced faults. To an extent, this model represents the voltage and frequency responses caused by balanced faults. However, it is based on only one representative manufacturer, and the model’s versatility and practicality need improvement. This study experimentally investigated the responses of EV chargers manufactured by several manufacturers. Each EV charger’s response was characterized. The developed model was improved to represent the response of each EV charger. The model parameters for each charger type were identified by comparing and validating the measured and simulated responses following balanced faults. An excellent match between the measured and simulated responses demonstrated that the developed model and the identified parameters accurately simulated the response following balanced faults. This model and the identified parameters can enable a more accurate assessment of EV charger impact on power system stability.

Niklas Jooß, Christoph Müller, Andreas Weiß

The reform of §14a of the German Energy Industry Act (EnWG) opens up the possibility for customers to choose variable grid fees for the first time. This legal adjustment enables distribution grid operators to design more flexible grid fees and to incentivise a potentially more efficient load management in the low-voltage grid. This paper includes a comprehensive analysis of the current design of variable grid fees and their congestion-relieving effect in the low-voltage grid. Particular attention is paid to the potential further development of grid charges towards a real-time pricing model that allows dynamic load control on the basis of real time grid utilisation. The results show that variable grid fee models can have impact on the stability and efficiency in the low-voltage distribution grid - both positive and negative. This work provides insights into the recent and possible future design of grid fees and their potential role in the energy transition.

Mohammed Altoumaimi, V. V. Loboda

The present study provides the consideration of a mode III interface crack in one-dimentional (1D) piezoelectric quasicrystal under antiplane phonon and phason loading and inplane electric field. Due to complex function approach all required electromechanical parameters are presented through vector-functions analytic in the whole complex plane except the crack region. The cases of electrically impermeable (insulated) and electrically limited permeable conditions on the crack faces are considered. In the first case a vector Hilbert problem in the complex plane is formulated and solved exactly and in the second one the quadratic equation with respect to the electric flux through the crack region is obtained additionally. Its solution permits to find phonon and phason stresses, displacement jumps (sliding) and also electric characteristics along the material interface. Analytical formulas are also obtained for the corresponding stress intensity factors related to each field. The numerical computations for three selected variants of the loading conditions was conducted and the resulting field distributions are visualised on the crack continuation beyond the crack and also inside of the crack region.

N. Sinthuja, M. Senthilvelan, K. Murali

In previous studies, the propagation of localized pulses (solitons, rogue waves and breathers) in electrical transmission lines has been studied. In this work, we extend this study to explore the transmission of positon solutions or positons in the modified Noguchi electrical transmission line model. By converting the circuit equations into the nonlinear Schrödinger equation, we identify positons, a special type of solution with algebraic decay and oscillatory patterns. Unlike solitons, which are used for stable energy transmission, positons provide persistent energy localization and controlled spreading over long distances. We consider second-order and third-order positon solutions and examine their transmission behaviour in electrical lines. We show that over long times, the amplitude and width of both second- and third-order positons remain largely unaffected, indicating stable transmission. We also analyze what are the parameters affect the amplitude and localization of this kind of waves. Our investigations reveal that the amplitude and localization of positons are significantly influenced by the parameter $ε$ that appear in the solution. Our findings have practical implications for improving energy transmission in electrical systems, where the management of wave localization and dispersion is crucial.

Lan Jin, Dowon Kim, A. Abu‐Siada et al.

A power transformer is one of the most critical and expensive assets in electric power systems. Failure of a power transformer would not only result in a downtime to the entire transmission and distribution networks but may also cause personnel and environmental hazards due to oil leak and fire. Hence, to enhance a transformer’s reliability and extend its lifespan, a cost-effective and reliable condition monitoring technique should be adopted from day one of its installation. This will help detect incipient faults, extend a transformer’s operational life, and avoid potential consequences. With the global trend to establish digital substation automation systems, transformer online condition monitoring has been given much attention by utilities and researchers alike. Several online and offline condition monitoring techniques have been recently proposed for oil-immersed power transformers. This paper is aimed at providing a state-of-the-art review for the various condition monitoring technologies used for oil-immersed power transformers. Concept of measurements and analysis of the results along with the future trend of condition monitoring techniques are presented.

A. Papavasiliou

Low-voltage distribution networks are emerging as an increasingly important component of power system operations due to the deployment of distributed renewable resources (e.g., rooftop solar supply) and the need to mobilize the flexibility of consumers that are connected to the low-voltage grid. The pricing of electric power at distribution nodes follows directly from the theory of spot pricing of electricity. However, in contrast to linearized lossless models of transmission networks, an intuitive understanding of prices at the distribution level presents challenges due to voltage limits, reactive power flows, and losses. In this paper, we present three approaches toward understanding distribution locational marginal prices by decomposing them: 1) through a duality analysis of the problem formulated with a global power balance constraint; 2) through a duality analysis of a second-order cone program relaxation; and 3) through an analysis of the impact of marginal losses on price. We discuss the relative strengths and weaknesses of each approach in terms of computation and physical intuition, and demonstrate the concepts on a 15-bus radial distribution network.

Yuqing Wang, Wenjie Fu, Xudong Zhang et al.

Abstract Accurately forecasting regional distributed photovoltaic (DPV) power is crucial in mitigating the negative impact of high DPV penetration on the reliability and resilience of the distribution network. However, most of the current photovoltaic power forecasting methods suffer from two key problems: (1) ignoring the asymmetric influence relationship among DPV sites; (2) lack of consideration of dynamic spatiotemporal correlation among DPV sites. As a result, these methods are unable to fully adapt to the characteristics of DPV, making it challenging to directly apply the existing forecasting methods to improve the accuracy of DPV power forecasting. To conquer this limitation, a dynamic directed Graph Convolution Neural Network (DDGCN) is applied to regional DPV ultra‐short‐term power forecasting. Unlike the conventional Graph Convolution Neural Network (GCN) based forecasting methods, the proposed method improves GCN to process the directed graph. On this basis, to capture the dynamic and directed adjacency relationship among graph nodes, a temporal attention mechanism is proposed and combined with the directed GCN model. In this way, the dynamic and asymmetric/directed relationships among DPV sites can be taken into account. It is worth noting that the DPVs’ adjacency relationship can be constructed without any prior knowledge by end‐to‐end model training. The simulation experiment proves that the prediction accuracy can be further improved by taking into account the dynamic directed relationship among the sites via a real DPV power dataset.

Victoria A. O'Brien, Vittal S. Rao, Rodrigo D. Trevizan

The cells in battery energy storage systems are monitored, protected, and controlled by battery management systems whose sensors are susceptible to cyberattacks. False data injection attacks (FDIAs) targeting batteries’ voltage sensors affect cell protection functions and the estimation of critical battery states like the state of charge (SoC). Inaccurate SoC estimation could result in battery overcharging and over discharging, which can have disastrous consequences on grid operations. This paper proposes a three-pronged online and offline method to detect, identify, and classify FDIAs corrupting the voltage sensors of a battery stack. To accurately model the dynamics of the series-connected cells a single particle model is used and to estimate the SoC, the unscented Kalman filter is employed. FDIA detection, identification, and classification was accomplished using a tuned cumulative sum (CUSUM) algorithm, which was compared with a baseline method, the chi-squared error detector. Online simulations and offline batch simulations were performed to determine the effectiveness of the proposed approach. Throughout the batch simulations, the CUSUM algorithm detected attacks, with no false positives, in 99.83% of cases, identified the corrupted sensor in 97% of cases, and determined if the attack was positively or negatively biased in 97% of cases.

Mohamed H. Hassan, Salah Kamel, Abd‐ElHady Ramadan et al.

Abstract The utilization of accurate models is crucial in the various stages of development for photovoltaic (PV) systems. Modelling these systems effectively allows developers to assess new modifications prior to the manufacturing phase, resulting in cost and time savings. This research paper presents a viable approach to accurately estimate both static and dynamic PV models. The proposed estimation method relies on a novel and enhanced optimization algorithm called leader artificial ecosystem‐based optimization (LAEO), which improves upon the original artificial ecosystem‐based optimization (AEO). The proposed LAEO algorithm integrates the adaptive probability (AP) and leader‐based mutation‐selection strategies to enhance the search capability, improve the balance between exploration and exploitation, and overcome local optima. To evaluate the effectiveness of LAEO, it was tested on 23 different benchmark functions. Additionally, LAEO was applied to estimate the parameters of static three‐diode PV models, as well as integral‐order and fractional‐order dynamic models. This paper showcases practical implementations of photovoltaic (PV) parameter estimation in various scenarios, including the static three‐diode model, dynamic integral order model (IOM), and fractional order model (FOM). The results were assessed from various angles to examine the precision, performance, and stability of the LAEO algorithm.

Suhail Afzal, Hazlie Mokhlis, Hazlee Azil Illias et al.

Abstract In recent decades, flash floods have become more common because of climate change and are considered a substantial risk for many cities worldwide. This catastrophic natural hazard presents a significant threat to critical infrastructure in urban areas, particularly the power distribution system. As modern societies are much more dependent on electrical energy these days, it is essential and imperative to make existing distribution systems resilient against flash flooding. Although researchers in this area have proposed various algorithms to impart resilience to a distribution system, however, the focus in these works is on wind‐related events such as hurricanes, cyclones, and windstorms. Therefore, here, the spatiotemporal effects of a flash flood on the distribution system are modelled using a grid‐based hydrodynamic model. The evolving line faults are then included in the proposed resilience‐oriented time horizon‐based service restoration model that also considers dynamic load demand, heavy uncertainties related to renewable generation, and interdependence among critical loads. Finally, the resilience of the distribution system's response is assessed using an operational resilience metric. The efficacy of the proposed framework is evaluated on IEEE 33‐bus and 69‐bus systems and the results show that the model provides an efficient restoration solution despite increased complexity caused by varying conditions.

Ahmad Bin Afzal, Nabil Mohammed, Shehab Ahmed et al.

Climate change has led to an increase in the frequency and severity of extreme weather events, posing significant challenges for power distribution systems. In response, this work presents a planning approach in order to enhance the resilience of distribution systems against climatic hazards. The framework systematically addresses uncertainties during extreme events, including weather variability and line damage. Key strategies include line hardening, backup diesel generators, and sectionalizers to strengthen resilience. We model spatio-temporal dynamics and costs through a hybrid model integrating stochastic processes with deterministic elements. A two-stage stochastic mixed-integer linear approach is developed to optimize resilience investments against load loss, generator operations, and repairs. Case studies on the IEEE 15-bus benchmark system and a realistic distribution grid model in Riyadh, Saudi Arabia demonstrate enhanced system robustness as well as cost efficiency of 10% and 15%, respectively.

Hexiao Li, Sixing Wu, Ruiqi Wang et al.

Abstract The distributed and privacy‐preserving attributes of fine‐grained smart grid data create obstacles to data sharing. As a result, federated learning emerges as an effective strategy for collaborative training in distributed load forecasting. However, poisoning attacks can interfere with training in the federated learning aggregation process, making it challenging to ensure the accuracy and safety of the global model in load forecasting. Therefore, the authors propose a secure aggregation federated learning method based on similarity and distance (Fed‐SAD) for distributed load forecasting. The server determines approximate global model parameters based on the similarity of the model parameters of the participants and aggregates the global model parameters using a distance‐based weighting method. Fed‐SAD effectively reduces the interference of poisoning attacks by securely aggregating models in short‐term load forecasting. Experimental results show that using the Fed‐SAD results in mean absolute percentage error (MAPE) reduction for certain participants by 19% on sign flipping attacks, MAPE reduction by 15% on additive noise attacks, and MAPE reduction by 4.5% without attack, compared to the Federated Average Aggregation algorithm. Furthermore, Fed‐SAD consistently maintains robustness and has excellent attack detection accuracy.

Md. Shamim Reza, Md. Maruf Hossain

Abstract This paper reports an algorithm for quick and precise estimation of the single‐phase grid frequency under DC offset and both odd and even harmonics. The proposed single‐phase grid frequency estimation method is derived from a three‐phase relation. It relies on a recursive discrete Fourier transform‐based orthogonal signal generator and a two samples‐based algorithm. The proposed approach is simple, demands low computational effort and generates the single‐phase grid frequency at a cost of only one fundamental period as the transient response time under the DC offset and both odd and even harmonics condition. It also produces enhanced performance when compared to several single‐phase grid frequency estimation methods documented in the technical literature. Computer simulations and laboratory experiments are conducted to demonstrate the usefulness of the proposed single‐phase grid frequency estimation method.

Arya Abdolahi, Rahim Ajabi Farshbaf, Abolfazl Abbaspour et al.

Achieving high distribution-reliability levels and concurrently minimizing operating costs are as the main issues in distribution system optimization. Determination of the optimal number and location of remote control switches (RCS) in the distribution system network is an essential issue from the reliability and economic points of view. To address these issues, this paper develops a novel multiobjective model from the distribution system viewpoint, wherein the primary objective, optimal RCS placement is implemented aiming at minimizing the operating costs, while in the second objective, the reliability index improvement is taken into account. So, a novel approach from a robust heuristic algorithm, modified non dominated sorting genetic algorithm (MNSGA-II), is developed and presented to solve this multiobjective mixed-integer non-linear programming problem. Simulation results received by the genetic algorithm have been compared with the other popular optimization algorithms, seperately. Results show that the proposed algorithm provides extensively the best performance, in terms of quality of the answer received and computational efficiency. The feasibility of the proposed algorithm was examined by application to two distribution feeders of the Tabriz city distribution network containing the fourth feeder of the TractorSazai substation.

Fu Shen, Yutao Zhang, Gefei Qiu et al.

Abstract The power system dynamics have consistently challenged the rapid and persistent proliferation of photovoltaic (PV) systems in power systems. In this paper, the authors propose the generalized discrete‐time equivalent model (GDEM) of PV power generation system using a fourth‐order dynamic equivalent model for representing the physical characteristics of PV power stations in power system dynamic studies. In addition, the authors propose a grid‐connected system model which includes modelling interfaces (MIs) for the GDEM of power grid and the GDEM of PV power generation system in dynamic studies. The proposed equivalent models of the power grid and PV power generation system will improve the simulation accuracy and speed in dynamic power system studies. The authors have used the IEEE 14‐bus system and simulated various types of short‐circuit faults and PV penetration levels in their study to demonstrate the merits of the proposed GDEM of grid‐connected system in power systems. The pertinent simulation results are analyzed and conclusions are presented.

Reza Sharifi Shahrivar, Hossein Gholizadeh, Ali Siadatan et al.

This paper has designed an upgraded form of the boost topology. The voltage ratio of the traditional step-up topology has been increased in quadratic form. Moreover, a low value of the duty cycle, number of components, and voltage/current stresses besides a high efficiency are bold features. The different parameters have been extracted for the ideal/non-ideal modes of the components and continuous/discontinuous current modes. In addition, the different features, such as the current/voltage stresses, have been compared. The efficiency of the designed topology has been extracted, and its various kind of power losses have been compared. The small-signal analysis has been done, and the bode diagram of the system has been extracted. Besides the increased voltage ratio of the designed topology compared to the traditional step-up converter, the continuity of the input current has remained a brilliant feature. Moreover, the semiconductors' stresses have been low-value compared to the recently proposed topologies. Moreover, higher efficiency besides higher voltage gain has been achieved. Finally, the experimental results have been compatible with the simulation and theoretical outcomes. The higher voltage gain of the proposed converter has been caused by the lower value of the duty cycle in comparison with the conventional boost converter, besides an acceptable efficiency and semiconductor stresses.