Hasil untuk "Distribution or transmission of electric power"

Mohsen Khalaf, Abdelrahman Ayad, M. H. K. Tushar et al.

Distribution systems are evolving from traditional passive networks into, what is known as, Active Distribution Networks (ADNs). Unlike traditional distribution networks, ADNs are characterized by bi-directional power flow, the high penetration of DERs, storage capabilities and sophisticated control strategies. Multiple layers of communications, sensing and computation are being integrated into ADNs for monitoring, control and protection of a variety of components and critical operations. This enhanced dependency on information and communication technologies, however, increases the exposure of ADNs to cyber-attacks. Several papers have been published in recent years with a focus on cyber-physical security (CPS) of smart grids. However, the published survey papers primarily emphasize the transmission level of smart grid threats and challenges, with little focus on the ADNs. Given the rapid deployment of ADNs and the increasing cyber threats against power grids and critical infrastructures, we are motivated, in this article, to present a review and survey focused, instead, on the latest research advancements in the area of CPS for ADNs. This paper represents the first survey of timely research in the area of CPS of ADNs with a focus on ADN critical operations and components. The cyber-physical aspects of each critical operation/component are analyzed. In addition, the challenges and requirements of associated communication protocols and standards are presented. Cybersecurity of ADN devices and sensors including Phasor Measurement Units (PMUs), smart meters, advanced metering infrastructure and protection relays are discussed in detail. Moreover, a thorough study of ADNs application drivers and enablers including microgrids, Electric Vehicles (EVs), Internet-of-Things (IoT) and smart homes is conducted. Potential and existing solutions by industry are highlighted. Finally, survey outcomes and directions for future work are presented to highlight emerging avenues of research.

Kristian Sevdari, Lisa Calearo, P. B. Andersen et al.

The transformation towards a sustainable power system calls for new ways of operating the network. In that regard, electric vehicles (EVs) with their charging infrastructure qualify as a flexible resource. This paper interconnects ancillary services and EV flexibility to help system operators (SOs) and flexibility providers understand the role and localize EV-chargers in the power system. First, the focus is on SOs. The manuscript reviews ancillary services based on power system operational challenges. The ancillary services are differentiated between 8 frequency and 32 flexibility services. These are then subdivided depending on the management control: the first group includes inertia, primary, and secondary/tertiary frequency control, while the second includes congestion management, voltage regulation, power quality, grid stability, and emission management. Of all the different services, the ones that can be provided by EV-charger are highlighted and classified into 12 geo-electrical charging clusters. Second, the focus is moved to the flexibility providers. Independently from location, to provide ancillary services with EVs, multiple actors are recognized: the end-user, the charging site operator (CSO), the charging point operator (CPO), the aggregator, the energy community, the distribution system operator (DSO), and the transmission system operator (TSO). The collaboration between the actors is today carried out by making alliances, to help exchange knowledge and gain confidence in ancillary services provision. In conclusion, the literature review presents the characteristics of 27 slow (up to 50 kW) smart chargers, the common flexibility features being scheduling (100%), modulation (89%), and phase switching (10%).

Fangxing Fran Li

Presents the recipients of (IEEE Open Access Journal of Power and Energy (OAJPE)) awards for (2024).

Yuechuan Tao, Jing Qiu, Shuying Lai et al.

The proliferation of electric vehicles (EVs) is an inevitable trend to realize transportation electrification. However, the increasing charging demand of EVs also brings challenges to future smart grids. To cope with the EV diffusion, this paper presents an adaptive fast charging station (FCS) strategy that considers the integrated network planning and quality of service (QoS) guarantee. First, based on the EV diffusion model and the proposed EV-integrated traffic assignment model, the charging demands at different regions and stages are forecasted. Based on the predicted spatial and temporal EV charging demand, a multistage stochastic distribution expansion planning model is presented, where the distribution network assets and FCSs are jointly considered. To guarantee the quality of the fast-charging services under EV diffusion, a QoS assessment is conducted based on the average waiting time and the average number of dissatisfied leaves. Finally, the proposed planning model allows several alternatives at both the distribution and transmission levels. The cost of electricity network expansion planning is considered as the adaptive cost arisen from the EV diffusion and the increase of the other electrical loads. We aim to find a planning strategy that can adapt to different penetration levels of EVs. The proposed framework and methodology are verified on the IEEE 24-bus power system encompassing 6 IEEE 33-bus distribution networks. It is found out that the proposed strategy shows superiority in both QoS and total costs.

Feruz Raximov, A. Taslimov, Ahror U. Majidov et al.

The article considers the basis of scientific research in the field of electric power industry the issues of transition to 20 kV voltage in the distribution power grids of Uzbekistan. The main advantages of this method are analysed, as well as the factors affecting power and energy losses in electrical systems and networks. The paper presents a schematic diagram of an electric network section, on which a comparative calculation and analysis of voltage, energy and power losses in 6/10/20 kV networks is carried out. Special attention is paid to the peculiarities of calculation of these parameters, as well as the basic expressions for their calculation and the resulting graphical relationships. From the analysis it can be concluded that it is reasonable to use 20 kV voltage in distribution networks. It allows to reduce power and energy losses, which is an important factor in the efficient operation of electric power systems, to increase line capacity and service range. However, when selecting the optimal voltage for certain conditions, it is necessary to take into account a number of factors, such as the length of transmission lines, the type of wires and transformers used, and the load level of the network.

Yuekuan Zhou

Climate change and extreme weather events impose urgent necessities on distributed energy systems with energy flexibility and resilience to survive the district power supply systems. Compared to centralized energy systems, distributed energy systems show more superiorities in power shifting, fast demand response, regional energy allocations, and so on. However, electrification transformation‐ enabled flexible energy sharing, smart energy integration, and advanced management are still in their infancy stages, with unsolved but urgent issues, like large‐scale energy system planning and optimization, energy trading and pricing mechanisms, so on. In this study, energy‐sharing economy with renewable integration and management in communities has been comprehensively reviewed. The “source–grid–load–storage” framework has been implemented on district energy systems with complex relationships among the energy supply–storage–transmission–distribution chain. Roles of energy sharing, integration, and management on energy system sustainability have been provided. Considering widely installed large‐scale renewable energy systems, planning and optimization platforms and tools are provided to guide the distributed/centralized system planning and accurate capacity sizing. Results showed that, multi‐directional power interactions with electrification in buildings and E‐mobility spatiotemporal energy sharing and smart grids enable high renewable penetration, fast power response, energy supply reliability, etc. Unlike traditional fossil fuel‐based power plants, distributed renewable‐supported energy systems (like BIPVs, electric vehicles, etc.) enable emerging energy sharing, integration, and management for energy flexibility and resilience with fast response and energy survivals. Roles of advanced energy include power shifting, fast demand response, regional energy allocations, and so on. Electricity market liberalization can incentivize multi‐stakeholders’ proactivity and market vitality for distributed renewable energy spatiotemporal microgrids. Dynamic energy pricing for the shared power is dependent on the supply–demand relationship, and cost–benefit allocations among different stakeholders need to be investigated for justice and fairness. To avoid performance over or underestimations, advanced approaches are highly necessary for large‐scale energy system planning and optimization. Research results can pave paths for upcoming studies in urban energy system planning, design, and optimization with high energy efficiency and low carbon emissions through joint collaborations from highly economically incentivized participators.

Sahar Rahim, Zhen Wang, Ke Sun et al.

Abstract This article introduces a Wasserstein distance‐based distributionally robust optimization model to address the transmission expansion planning considering renewable‐based microgrids (MGs) under the impact of uncertainties. The primary objective of the presented methodology is to devise a robust expansion strategy that accounts for both long‐term uncertainty and short‐term variability over the planning horizon from the perspective of a central planner. In this framework, the central planner fosters the construction of appropriate transmission lines and the deployment of optimal MG‐based generating units among profit‐driven private investors. The Wasserstein distance uncertainty set is used to characterize the long‐term uncertainty associated with future load demand. Short‐term uncertainties, stemming from variations in load demands and production levels of stochastic units, are modeled through operating conditions. To ensure the tractability of the proposed planning model, the authors introduce a decomposition framework embedded with a modified application of Bender's method. To validate the efficiency and highlight the potential benefits of the proposed expansion planning methodology, two case studies based on simplified IEEE 6‐bus and IEEE 118‐bus systems are included. These case studies assess the effectiveness of the presented approach, its ability to navigate uncertainties, and its capacity to effectively optimize expansion decisions.

Jiayi Liu, Xiaoqing Xie, Feng Wang et al.

Abstract Compared to offline measurement (interrupting the applied voltage before measurement), online measurement of surface charge on gas‐insulated transmission line (GIL) insulators effectively avoids the impact of spontaneous dissipation of charges. Thus, the accuracy of results can be improved. In this article, a measurement model of capacitive electrostatic probes for surface charges on ±320 kV GIL tri‐post insulator is established. The geometry of probes is optimized. The feasibility of online measurement of surface charges is analyzed. Results indicate that the surface leakage distance of induced charges is positively related to the length. Furthermore, as the diameter of probes increases, the maximum electric field on the sensitive electrode surface rises, while the radius of the sensitive electrode has the opposite effect. Hence, the diameter of the probe is 6 mm. The length and radius of sensitive electrodes are 50 mm and 1.2 mm, respectively. For online measurement of surface charges on ±320 kV tri‐post insulators, the induced potential distribution of the probe is consistent with surface charges. Therefore, the capacitive electrostatic probe in the embedded electrode is appropriate for the online measurement of surface charges on tri‐post insulators. It provides a reference for avoiding flashover triggered by surface charge accumulation on DC GIL insulators.

Zhongxue Chang, Jifei Yan, Chenhao Zhang et al.

Abstract There exist problems of hard coordination and threshold setting as well as low sensitivity in overcurrent relay due to the bidirectional and small fault current when distributed generators are integrated into the distribution network. This paper introduces ferrite rings (FRs) to act as boundaries of distribution feeders, and a peak time of voltage traveling wave‐based protection is proposed. The characteristics of FRs are analyzed and their feasibility as line boundary is validated. The fault characteristics of internal and external faults are analyzed when FRs are installed at both ends of the protected feeder. The results show that the peak time of the voltage travelling wave of the internal fault is far smaller than that of the external faults. According to the difference, the fault detection method and the protection scheme are proposed. Simulations in PSCAD and experiment validate that the proposed protection principle can reliably distinguish between internal and external faults. Besides, the proposed protection scheme has higher sensitivity compared to ROCOV‐based protection.

Sarvesh Babu R G, Mithra Vinda Reddy K, Shwetha S et al.

Abstract The global warming crisis, together with environmental concerns, has already led governments to replace traditional fossil‐fuel cars with low‐emission Electric Vehicles (EVs). This replacement has resulted in the addition of a large number of EVs capable of connecting to the grid. A coordinated charging method is needed to promote EVs on a large scale while preventing grid overloading. In this work, EVs are categorized based on their battery capacity, as cars, trucks, and buses. A charging/discharging mechanism based on Real Time Pricing for each hour is developed for a 20‐min block that has been formed. The locations of EV charging stations have been identified using Voltage Stability Index. In the present work, the power loss when Distributed Generator (DG) units are deployed after the EVs are located in the system for charging and discharging is analyzed. The DGs are considered as solar‐based or wind‐based generators for studying the economic benefit of such an investment under two different weather scenarios and topologies on standard test systems. The results thus obtained give an insight into the various technical and economic benefits.

Ghulam Abbas, Zhi Wu, Aamir Ali

Abstract This paper emphasizes the integration of wind and photovoltaic (PV) generation with battery energy storage systems (BESS) in distribution networks (DNs) to enhance grid sustainability, reliability, and flexibility. A novel multi‐objective optimization framework is introduced in this study to minimize energy supply costs, emissions, and energy losses while improving voltage deviation (VD) and voltage stability index (VSI). The proposed framework comprising normal boundary intersection (NBI) and decomposition‐based evolutionary algorithms (DBEA) determines the optimal siting and sizing of renewable‐based distributed resources, considering load demand variations and the intermittency of wind and solar outputs. The comparative analysis establishes that the proposed strategy performs better than many contemporary algorithms, specifically when all the objective functions are optimized simultaneously. The validation of the proposed framework was carried out on the standard IEEE‐33 bus test network, which demonstrates significant percentage savings in energy supply costs (49.6%), emission rate (62.2%), and energy loss (92.3%), along with enormous improvements in VSI (91.9%) and VD (99.8953%). The obtained results categorically underline the efficiency, reliability, and robustness of the proposed approach when employed on any complex distribution network comprising multiple renewable energy sources and battery storage systems.

Mohammad Hosein Alaei, Mohammad Amin Latify

Abstract Conservation voltage reduction (CVR) is a strategy that tries to save energy consumption by managing consumers’ voltage. On the other hand, enhancing reactive power compensation in the power system gives rise to CVR implementation more effectively. This paper addresses how the power system planner could encourage investment to establish the above‐mentioned topics. Here, a model for encouraging industrial loads to dynamically invest in implementing the CVR strategy over the planning horizon is presented. To make CVR implementation more efficient, investment in upgrading plug‐in electric vehicles (PEVs) chargers to be utilized as reactive power compensators is also considered. Industrial loads benefit from saving in their electricity bills and incentive payments that might be paid by utilities (if necessary). The objective function of the proposed planning model is to maximize the energy‐saving of industrial loads and to minimize incentive payment by electric utilities over the planning horizon. This objective is achieved subject to that the investment plan is economically feasible. Moreover, power system operation constraints in the planning horizon based on AC power flow equations and voltage‐dependent load models are considered. The proposed planning problem is modelled as a non‐linear optimization problem that can be solved by off‐the‐shelf software, for example, GAMS. The proposed model is applied to the Ontario transmission system. The numerical results show the proposed model's effectiveness in designing an investment plan for industrial loads to implement the CVR strategy and upgrade PEVs’ chargers.

M. Gazzea, Michael Pacevicius, D. Dammann et al.

Vegetation Management is a significant preventive maintenance expense in many power transmission and distribution companies. Traditional Vegetation Management operational practices have proven ineffective and are rapidly becoming obsolete due to the lack of frequent inspection of vegetation and environmental states. The rise of satellite imagery data and machine learning provides an opportunity to close the loop with continuous data-driven vegetation monitoring. This paper proposes an automated framework for monitoring vegetation along power lines using high-resolution satellite imagery and a semi-supervised machine learning algorithm. The proposed satellite-based vegetation monitoring framework aims to reduce the cost and time of power line monitoring by partially replacing ground patrols and helicopter or drone inspection with satellite data analytics. It is implemented and demonstrated for a power distribution system operator (DSO) in the west of Norway. For further assessment, the satellite-based algorithm outcomes are compared with LiDAR survey data collected by helicopters. The results show the potential of the solution for reducing the monitoring costs for electric utilities.

Guorui Xu, Zhenzhen Wang, Jingdi Zhou et al.

A synchronous condenser (SC) can provide the reactive power for the Ultra High Voltage Direct Current (UHVDC) converter station to keep voltage stability and prevent commutation failure. The single-phase short circuit at a transmission line is prevalent and it can result in not only the voltage drop but also the increase of the rotor loss and temperature of the SC. In order to study the ability of the SC to withstand a single-phase short-circuit fault, the rotor loss and temperature field of a 300-MVar SC are studied by coupling the electromagnetic and temperature field models of the SC with the models of the electric circuit and power grid. The loss distributions in the rotor core and slot wedges are calculated under a single-phase short-circuit fault at the different positions of the transmission line. The rotor temperature distributions of the SC under over- and under-excitations are calculated and verified by the experiments. The influence of short-circuit duration on the rotor temperature of the SC is calculated under the single-phase short circuit. The study can provide a theoretic basis for the improvement of the operating ability of the SC under the single-phase short-circuit faults.

Mohsen Darabian, Amir Bagheri, Sajjad Yousefi

Abstract The main aim of this paper is to improve dynamic performance of a multi‐terminal DC (MTDC) grid in a wind‐integrated AC power system through DC voltage control. The proposed approach is based on design of robust H∞ controller and loop shaping along with mutual quality decomposition method (MQDM). For extracting transfer function of the plant, model of Master‐Slave control system is converted to standard feedback control system. Then, based on the obtained difference between singular‐value curves of the main open‐loop system and the proposed method, the weighting functions of robust H∞ controller are selected. In the next step, by using the MQDM technique, the transfer function ofthe system in state‐space form is evaluated to extract gain of the robust controller. For practicality of the conducted approach, singular‐value order reduction Hankel algorithm along with frequency response analysis have been used for designing the gain of the robust controller. The developed method has been implemented on the MTDC converter in the wind farm side to control the voltage of DC grid. The simulations are accomplished in MATLAB, where by considering different uncertainties in the DC grid, wind unit, and the AC grid, robustness of the proposed approach has been clearly demonstrated.

Xiaosheng Zhang, Zesan Liu, Tao Ding et al.

Abstract The carbon capture and storage (CCS) technique gains much attention due to its role in reducing CO2 emissions. By introducing flexible CCS devices into conventional power plants, the low‐carbon economic operation of the power system can be achieved. However, the uncertainty of renewable energy makes it hard to obtain an optimal operation policy. First, the detailed model of CCS consisting of bypass venting stacks, solvent storage tanks, absorber, and stripper is described. Then, a low‐carbon economic dispatch model of the power system with CCS is proposed to minimize the total operation and renewable energy abandonment penalty costs. Next, the problem is reformulated as multi‐stage stochastic programming, and the stochastic dual dynamic programming (SDDP) method is applied to relieve the computation burden. To control the probability of stopping the algorithm prematurely, a new stopping criterion based on a two‐sided hypothesis test is proposed. Finally, the effectiveness of the proposed model and the new stopping criterion is demonstrated by case studies on a practical power system.

Oleg Shutenko, Oleksii Kulyk

Abstract This paper proposes a method for recognising the fault type using a set of diagnostic criteria. Existing approaches to the interpretation of dissolved gas analysis (DGA) results usually rely on single diagnostic criteria. The proposed method solves the problems of incomplete use of diagnostic information and discrepancies in the norms and criteria for recognising the same fault inherent in the existing methods. The feature of the method is the analysis of the compliance of the DGA results of the diagnosed equipment with the ones of the equipment with a confirmed diagnosis from the fault database. This approach outperforms the existing methods in the number of faults recognised, allowing a wider range of faults to be detected, including combined faults. In addition, the method provides an opportunity to identify possible causes and localise the fault. This feature is unique and provides a significant advantage when interpreting DGA results. The proposed method demonstrates significantly higher accuracy (100%) in recognising various fault types, including combined faults, in comparison to existing methods (about 50%). The proposed method has a 60% success rate in determining the cause and location of a fault, but this figure depends on the database with faults of various types used.

Jane Lu Hsu, Minh‐Trang Vo Nguyen, You‐Ren Chen et al.

Abstract Electricity generation in Taiwan is mainly from thermal, nuclear, and renewable sources. With nearly four decades of monthly data (from January 1982 to January 2022) used in analytics, the forecasting results reveal the patterns of electricity generation in Taiwan. Exponential smoothing and Holt–Winters seasonal models are used for time‐series forecasting, and scenario analysis is applied to simulate possible paths for nuclear phase‐out in Taiwan by 2025. Taking the fact of Taiwan's lack of energy independence into account, transition for nuclear phase‐out may require a substantial leap to meet the demand. The feasibility of electricity generation using current thermal power capacity and renewable energy remain challenging.

J. Riba, M. Moreno-Eguilaz, S. Bogarra

Humanity faces important challenges concerning the optimal use, security, and availability of energy systems, particularly electrical power systems and transmission lines. In this context, data-driven predictive maintenance plans make it possible to increase the safety, stability, reliability, and availability of electrical power systems. In contrast, strategies such as dynamic line rating (DLR) make it possible to optimize the use of power lines. However, these approaches require developing monitoring plans based on acquiring electrical data in real-time using different types of wireless sensors placed in strategic locations. Due to the specific conditions of the transmission lines, e.g., high electric and magnetic fields, this a challenging problem, aggravated by the harsh outdoor environments where power lines are built. Such sensors must also incorporate an energy harvesting (EH) unit that supplies the necessary electronics. Therefore, the EH unit plays a key role, so when designing such electronic systems, care must be taken to select the most suitable EH technology, which is currently evolving rapidly. This work reviews and analyzes the state-of-the-art technology for EH focused on transmission lines, as it is an area with enormous potential for expansion. In addition to recent advances, it also discusses the research needs and challenges that need to be addressed. Despite the importance of this topic, there is still much to investigate, as this area is still in its infancy. Although EH systems for transmission lines are reviewed, many other applications could potentially benefit from introducing wireless sensors with EH capabilities, such as power transformers, distribution switches, or low- and medium-voltage power lines, among others.

S. Tavarov, I. Zicmane, Svetlana Beryozkina et al.

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