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1
Marques, Goncalo, Vitor Monteiro e Joao L. Afonso. "A Full-Controlled Bidirectional Dual-Stage Interleaved Converter for Interfacing AC and DC Power Grids". Energies 17, n. 13 (27 giugno 2024): 3169. http://dx.doi.org/10.3390/en17133169.
Testo completoAbstract (sommario):
Power grids are progressing, and the possibility of incorporating DC grids toward hybrid AC/DC grids is gaining increasing relevance, as several technologies available nowadays are operating natively in DC. This paper proposes a topology of a full-controlled bidirectional dual-stage interleaved converter for interfacing hybrid AC/DC grids. The topology is based on a dual-stage architecture, constituted by an AC/DC converter and by a DC/DC converter, both based on interleaved power converters. On the AC side, which is connected to the main AC power grid, the proposed dual-stage architecture operates with sinusoidal current in phase or phase opposition with the voltage, meaning a bidirectional operation. In addition, it has the possibility of interfacing with other AC loads, such as domestic electrical appliances, or with an AC microgrid. The DC link, formed by the AC/DC power stage, is interfaced with a DC power grid, which provides numerous advantages, e.g., for interfacing battery electric vehicles directly charged in DC, as well as other DC loads, such as renewable energy sources. The DC/DC power stage is considered for interfacing with an energy storage system, which is capable of bidirectional power exchange with the DC grid or with the AC grid through the AC/DC power stage. A complete laboratory prototype was designed and developed, with the unified control algorithms implemented on a digital signal processor. The experimental results validated the operation of the full-controlled bidirectional dual-stage interleaved converter based on the specifications for the hybrid AC/DC grid, such as bidirectional operation, synchronization with the AC power grid, predictive current control, interleaved operation on both AC/DC and DC/DC power stages, DC-link voltage control for the DC grid, as well as the operation with different power levels.
2
Roy, Gaurav Kumar, Marco Pau, Ferdinanda Ponci e Antonello Monti. "A Two-Step State Estimation Algorithm for Hybrid AC-DC Distribution Grids". Energies 14, n. 7 (2 aprile 2021): 1967. http://dx.doi.org/10.3390/en14071967.
Testo completoAbstract (sommario):
Direct Current (DC) grids are considered an attractive option for integrating high shares of renewable energy sources in the electrical distribution grid. Hence, in the future, Alternating Current (AC) and DC systems could be interconnected to form hybrid AC-DC distribution grids. This paper presents a two-step state estimation formulation for the monitoring of hybrid AC-DC grids. In the first step, state estimation is executed independently for the AC and DC areas of the distribution system. The second step refines the estimation results by exchanging boundary quantities at the AC-DC converters. To this purpose, the modulation index and phase angle control of the AC-DC converters are integrated into the second step of the proposed state estimation formulation. This allows providing additional inputs to the state estimation algorithm, which eventually leads to improve the accuracy of the state estimation results. Simulations on a sample AC-DC distribution grid are performed to highlight the benefits resulting from the integration of these converter control parameters for the estimation of both the AC and DC grid quantities.
3
Yu, Dong, Shan Gao, Xin Zhao, Yu Liu, Sicheng Wang e Tiancheng E. Song. "Alternating Iterative Power-Flow Algorithm for Hybrid AC–DC Power Grids Incorporating LCCs and VSCs". Sustainability 15, n. 5 (3 marzo 2023): 4573. http://dx.doi.org/10.3390/su15054573.
Testo completoAbstract (sommario):
AC–DC power-flow calculation is the basis for studying HVDC systems. Since traditional iterative methods need many alternative iterations and have convergence problems, this paper proposes an alternating iterative power-flow algorithm for hybrid AC–DC power grids incorporating line-commutated converters (LCCs) and voltage source converters (VSCs). Firstly, the algorithm incorporates the converter interface model into the AC side, considering the influence of the DC side on the AC side, and establishes an AC-augmented Jacobian matrix model with LCC/VSC interface equation variables. Then, according to the type of converter, control mode, and DC grid control strategy, a DC grid power-flow calculation model under various control modes is established for realizing the power-flow decoupling calculation of AC–DC power grids incorporating LCCs and VSCs. The accuracy and effectiveness of the improved algorithm are evaluated using modified IEEE 57 bus AC–DC networks and the CIGRE B4 DC grid test system. The improved algorithm is applicable to various DC grid control modes and considers the reasonable adjustment of the DC grid variable constraints and operating modes.
4
Rodrigues, Justino, Carlos Moreira e João Peças Lopes. "Fault-Ride-Through Approach for Grid-Tied Smart Transformers without Local Energy Storage". Energies 14, n. 18 (7 settembre 2021): 5622. http://dx.doi.org/10.3390/en14185622.
Testo completoAbstract (sommario):
The Smart Transformer (ST) is being envisioned as the possible backbone of future distribution grids given the enhanced controllability it provides. Moreover, the ST offers DC-link connectivity, making it an attractive solution for the deployment of hybrid AC/DC distribution grids which offer important advantages for the deployment of Renewable Energy Sources, Energy Storage Systems (ESSs) and Electric Vehicles. However, compared to traditional low-frequency magnetic transformers, the ST is inherently more vulnerable to fault disturbances which may force the ST to disconnect in order to protect its power electronic converters, posing important challenges to the hybrid AC/DC grid connected to it. This paper proposes a Fault-Ride-Through (FRT) strategy suited for grid-tied ST with no locally available ESS, which exploits a dump-load and the sensitivity of the hybrid AC/DC distribution grid’s power to voltage and frequency to provide enhanced control to the ST in order to handle AC-side voltage sags. The proposed FRT strategy can exploit all the hybrid AC/DC distribution grid (including the MV DC sub-network) and existing controllable DER resources, providing FRT against balanced and unbalanced faults in the upstream AC grid. The proposed strategy is demonstrated in this paper through computational simulation.
5
Monteiro, Vitor, Luis F. C. Monteiro, Francesco Lo Franco, Riccardo Mandrioli, Mattia Ricco, Gabriele Grandi e João L. Afonso. "The Role of Front-End AC/DC Converters in Hybrid AC/DC Smart Homes: Analysis and Experimental Validation". Electronics 10, n. 21 (25 ottobre 2021): 2601. http://dx.doi.org/10.3390/electronics10212601.
Testo completoAbstract (sommario):
Electrical power grids are rapidly evolving into smart grids, with smart homes also making an important contribution to this. In fact, the well-known and emerging technologies of renewables, energy storage systems and electric mobility are each time more distributed throughout the power grid and included in smart homes. In such circumstances, since these technologies are natively operating in DC, it is predictable for a revolution in the electrical grid craving a convergence to DC grids. Nevertheless, traditional loads natively operating in AC will continue to be used, highlighting the importance of hybrid AC/DC grids. Considering this new paradigm, this paper has as main innovation points the proposed control algorithms regarding the role of front-end AC/DC converters in hybrid AC/DC smart homes, demonstrating their importance for providing unipolar or bipolar DC grids for interfacing native DC technologies, such as renewables and electric mobility, including concerns regarding the power quality from a smart grid point of view. Furthermore, the paper presents a clear description of the proposed control algorithms, aligned with distinct possibilities of complementary operation of front-end AC/DC converters in the perspective of smart homes framed within smart grids, e.g., enabling the control of smart homes in a coordinated way. The analysis and experimental results confirmed the suitability of the proposed innovative operation modes for hybrid AC/DC smart homes, based on two different AC/DC converters in the experimental validation.
6
Aravind, S. P., e E. Darwin Suthar. "Design & Analysis of Hybrid Micro Grid with DC Connection at Back to Back Converter". Asian Journal of Electrical Sciences 3, n. 1 (5 maggio 2014): 1–10. http://dx.doi.org/10.51983/ajes-2014.3.1.1919.
Testo completoAbstract (sommario):
A micro grid is a localized grouping of electricity generation, energy storage, and loads that normally operate connected to a traditional centralized grid (macro grid). This single point of common coupling with the macro grid can be disconnected. The micro grid can then function autonomously. Generation and loads in a micro grid are usually interconnected at low voltage. From the point of view of the grid operator, a connected micro grid can be controlled as if it were one entity. Micro grid generation resources can include fuel cells, wind, solar, or other energy sources. The necessity of an AC or DC micro grid is governed by available micro sources and connected loads. A hybrid structure can ensure a sustainable configuration blending both the forms. In this paper, a hybrid micro grid structure for a grid connected micro grid with DC connection at back to back (B2B) converters is proposed. While a B2B connection between two AC systems could bestow a reliable, isolated and efficient coupling,an extra DC bus connection can facilitate use of the DC micro sources. The DC bus can supply the local DC loads and can also trade part of the power with the AC grids. The voltage support at the DC link (of the B2B converters) can be used for the DC bus formation. Different power management strategies with fixed power references or decentralized power distribution in AC/DC sides are proposed and validated with simulations in MATLAB.
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Bakeer, Abualkasim, Andrii Chub, Abderahmane Abid, Sherif A. Zaid, Thamer A. H. Alghamdi e Hossam S. Salama. "Enhancing Grid-Forming Converters Control in Hybrid AC/DC Microgrids Using Bidirectional Virtual Inertia Support". Processes 12, n. 1 (5 gennaio 2024): 139. http://dx.doi.org/10.3390/pr12010139.
Testo completoAbstract (sommario):
This paper presents a new grid-forming strategy for hybrid AC/DC microgrids using bidirectional virtual inertia support designed to address weak grid conditions. The stability of hybrid AC/DC microgrids heavily relies on the AC mains frequency and the DC-link voltage, and deviations in these factors can lead to undesirable outcomes such as load curtailments and power system congestions and blackouts. This paper introduces a unique approach that leverages bidirectional virtual inertia support to enhance the stability and reliability of hybrid AC/DC microgrids under weak grid conditions. The proposed strategy employs virtual inertia as a buffer to mitigate rapid changes in DC-link voltage and AC frequency, thereby enhancing system stability margins. This strategy significantly contributes to a more stable and reliable grid operation by reducing voltage and frequency fluctuations. A standard hybrid AC/DC microgrid configuration is used to implement the bidirectional virtual inertia support, where a bidirectional interlinking converter control is adjusted to deliver inertia support to both the AC and DC subgrids. This converter utilizes the DC grid voltage and AC grid frequency as inputs, effectively managing active power balance and implementing auxiliary functions. Extensive simulations are conducted under weak grid conditions and standalone mode to validate the effectiveness of the proposed strategy. The simulation results demonstrate a remarkable improvement in frequency nadir, rate-of-change-of-frequency (RoCoF), and DC bus voltage deviation in the hybrid AC/DC microgrids. The bidirectional virtual inertia support substantially reduces voltage and frequency fluctuations, enhancing the microgrid stability and resilience. There is an improvement of over 45% and 25% in the frequency deviation and voltage deviation, respectively, achieved through implementing the proposed control strategy.
8
Li, Chenghao, Di Zhang, Zhiwei Liu, Yulong Xiong, Tianhang Yu, Ze Gao e Shihong Miao. "An Evaluation Method of Renewable Energy Resources’ Penetration Capacity of an AC-DC Hybrid Grid". Energies 15, n. 7 (31 marzo 2022): 2550. http://dx.doi.org/10.3390/en15072550.
Testo completoAbstract (sommario):
With increasingly more renewable energy being integrated into the AC-DC hybrid grid, the grid shows more complex dynamic characteristics due to the mutual coupling of HVDC and renewable energy. To evaluate the renewable energy resources’ penetration capacity of the AC-DC hybrid grid, this paper proposes an evaluation method of the renewable energy resources’ penetration capacity of an AC-DC hybrid grid, which considers both economy and safety. Firstly, indicators are proposed for an evaluation of the economy and safety of the AC-DC hybrid grid integrated with renewable energy, where both static and transient stability indicators are considered. Secondly, to maximize the renewable energy penetration capacity and minimize the network loss, an optimization model of the renewable energy penetration capacity of the AC-DC hybrid grid is established considering the static and transient stability constraints. Then, a heuristic solution method for solving the renewable energy penetration capacity optimization model is proposed. Finally, based on the improved IEEE 39 node system, a case analysis is carried out. The simulation results verify the correctness and effectiveness of the proposed method.
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Pokakul, Wilailuk, e Nipon Ketjoy. "Performance Analyzing of Stand-Alone PV Hybrid Mini-Grid System with PV at DC and AC Coupling". Applied Mechanics and Materials 839 (giugno 2016): 23–28. http://dx.doi.org/10.4028/www.scientific.net/amm.839.23.
Testo completoAbstract (sommario):
Stand-alone PV system has been originally developed to feed solar energy produced by PV modules into the system by using solar charger controller at DC bus called “DC Coupling” for long time. In Late 1990 there is a new concept of feeding solar energy to the PV system at AC bus called “AC Coupling”. The AC coupling system uses grid connected inverter to convert energy produced by PV modules and synchronize output to AC distribution line. In mini grid system the common AC output of Bi-directional inverters or diesel generators performs as grid forming device to supply distribution line. Since 1990 there are stand-alone PV systems designed by using DC coupling or AC coupling which each type of PV coupling system highlight their advantage over the other. The work in this document presents a comparison of the efficiency of DC coupling and AC coupling PV system design in a hybrid mini-grid and finally proposes the alternative PV system design by using the “Dual DC and AC coupling” PV system in a hybrid mini-grid design. The HOMER Pro micro-grid analysis tool which can simulate DC and AC coupling PV system is used to compare leverage cost of energy (LCOE) of different type of PV hybrid mini-grid system. The simulation software which can do performance analyzing metric according to IEC 61724 and IEA-PVPS T2 is created in this study in order to simulate system operation and performance using DC, AC and dual DC and AC coupling PV system. The conclusion can clearly identify the best PV system in hybrid mini-grid in terms of LCOE and system performance.
10
Luo, Yi, Yin Zhang, Muyi Tang, Youbin Zhou, Ying Wang, Defu Cai e Haiguang Liu. "A Novel Receiving End Grid Planning Method with Mutually Exclusive Constraints in Alternating Current/Direct Current Lines". Sustainability 13, n. 13 (25 giugno 2021): 7141. http://dx.doi.org/10.3390/su13137141.
Testo completoAbstract (sommario):
The large-scale application of high-voltage direct current (HVDC) transmission technology introduces mutually exclusive constraints (MEC) into the power grid planning, which deepens the complexity of power grid planning. The MECs decrease the planning efficiency and effectiveness of the conventional method. This paper proposes a novel hybrid alternating current (AC)/direct current (DC) receiving end grid planning method with MECs in AC/DC lines. The constraint satisfaction problem (CSP) is utilized to model the MECs in candidate lines and then the detailed planning model, in which mutually exclusive candidate lines are described by mutually exclusive variable and constraint sets. Additionally, the proposed planning model takes the hybrid AC/DC power system stability into consideration by introducing the multi-infeed short circuit ratio (MISCR). After establishing the hybrid AC/DC receiving end grid planning model with MECs, the backtracking search algorithm (BSA) is used to solve the optimal planning. The effectiveness of the proposed hybrid AC/DC grid planning method with MECs is verified by case studies.
11
Hwang, Sungchul, Sungyoon Song, Gilsoo Jang e Minhan Yoon. "An Operation Strategy of the Hybrid Multi-Terminal HVDC for Contingency". Energies 12, n. 11 (28 maggio 2019): 2042. http://dx.doi.org/10.3390/en12112042.
Testo completoAbstract (sommario):
The application of the direct current (DC) transmission is increasing through the interconnection between grids or the renewable energy resource integration. Various types of DC transmission topology are researched, and the hybrid multi-terminal high voltage DC (HVDC), called the “MTDC”, is one of the research subjects. The hybrid multi-terminal HVDC is the MTDC system that is composed with the Line Commutated Converter (LCC) and Voltage Source Converter (VSC). Most hybrid MTDC research has been focused on the connection of the renewable energy generation sources, especially offshore wind farms. However, the DC grid built with a hybrid MTDC was recently proposed due to the development of the converter technology. Therefore, the DC grid is expected to be able to substitute some parts of the transmission grid instead of the alternating current (AC) system, and the operation strategies of the DC grid are still being researched. The DC grid has the advantage of being able to control the power flow, which can even improve the stability of the connected AC system. The dynamic model is required to analyze the improvement of the AC system by the operation strategy of the hybrid MTDC, however, there is no generic model for the system. In this paper, an operation strategy of the hybrid MTDC is proposed to improve the stability of the AC power system by increasing the utilization of parallel AC transmission lines under the contingency condition. Furthermore, studies on the modeling method for a hybrid MTDC analysis were performed. The proposed modeling method and operation strategy were verified in simulations for which a modified IEEE 39 bus test system was used. The improvement of transient stability by the proposed hybrid MTDC system was shown in the simulation results.
12
Razzaq, Syed Abdul, e Vairavasamy Jayasankar. "Energy management system for AC/DC HMGS integrated with interconnected renewable sources and interlinking converter". International Journal of Applied Power Engineering (IJAPE) 12, n. 1 (1 marzo 2023): 24. http://dx.doi.org/10.11591/ijape.v12.i1.pp24-36.
Testo completoAbstract (sommario):
AC/DC hybrid micro grid system (HMGS) is designed with renewable energy sources (RES) and battery energy storage system (BESS) with unique control schemes, interfaced with multi terminal interlinking converters (ILCs). This ILC operates on droop control scheme to guarantee bidirectional power sharing to AC/DC sub grids. The power sources in AC/DC sub grids like PV, Fuel cell, BESS are controlled by advance control methods for maximum power extraction with power quality. A three-level control structure is designed for optimal energy management system (EMS). The first level confirms the power balance in AC/DC sub grid with autonomous bidirectional power transfer via ILC in islanded mode. The second level tracks the batteries state of charge (SoC), based on the minimum and maximum SoC the battery operates for charging and discharging. The third level gives the power redundant capability for critical loads connected in AC/DC sub grid for DC system and single-phase system.
13
Pan, Hao, Ming Ding, Rui Bi e Lei Sun. "Research on Cooperative Planning of Distributed Generation Access to AC/DC Distribution (Micro) Grids Based on Analytical Target Cascading". Energies 12, n. 10 (15 maggio 2019): 1847. http://dx.doi.org/10.3390/en12101847.
Testo completoAbstract (sommario):
With the wide application of distributed generation (DG) and the rapid development of alternating current/direct current (AC/DC) hybrid microgrids, the optimal planning of distributed generation connecting to AC/DC distribution networks/microgrids has become an urgent problem to resolve. This paper presents a collaborative planning method for distributed generation access to AC/DC distribution (micro) grids. Based on the grid structure of the AC/DC distribution network, the typical interconnection structure of the AC/DC hybrid microgrid and AC/DC distribution network is designed. The optimal allocation models of distributed power supply for the AC/DC distribution network and microgrid are established based on analytical target cascading. The power interaction between the distribution network and microgrid is used to establish a coupling relationship, and the augmented Lagrangian penalty function is used to solve the collaborative programming problem. The results of distributed power supply allocation are obtained, solving the problem so that distribution generation with different capacity levels is connected to the power grid system in a single form.
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Chaurase, Payal, e Pankaj Ramtekkar. "A new design of control & power management strategies of hybrid ac-dc microgrids toward high power quality". Journal of Physics: Conference Series 2089, n. 1 (1 novembre 2021): 012036. http://dx.doi.org/10.1088/1742-6596/2089/1/012036.
Testo completoAbstract (sommario):
Abstract The micro grid idea provides for the lack of several reversing switches to unitary AC-DC grid that enables connection and charges (loads) to the electrical systems with changeable regenerative AC and CC sources. Safe operation and gadget safety involve digital integration with utilities/grid through power converters. Enhanced client reliability, decreased input losses, local voltages are supported, and waste heat efficiency increased, voltage drop or interruptible supply of electricity can be customized to satisfy their unique customer demands. Work at present Analyses the performance in grid tie mode of hybrid AC/DC systems. Here are PV systems, PV systems, For the construction of microgrids wind turbine generators and batteries are employed. Convert procedures for the correct coordination of AC sub-grids to DC subs-grids have also been established for converters. MATLAB/SIMULINK environment results are generated.
15
Peng Wang, L. Goel, Xiong Liu e Fook Hoong Choo. "Harmonizing AC and DC: A Hybrid AC/DC Future Grid Solution". IEEE Power and Energy Magazine 11, n. 3 (maggio 2013): 76–83. http://dx.doi.org/10.1109/mpe.2013.2245587.
Testo completo
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Gao, Jing, Yuan Zhao, Yi Lu e Guangda Xu. "Resonance Detection Method of AC-DC Hybrid Micro-grid Based on Wavelet Transform and Fast Fourier Transform". Journal of Physics: Conference Series 2747, n. 1 (1 maggio 2024): 012003. http://dx.doi.org/10.1088/1742-6596/2747/1/012003.
Testo completoAbstract (sommario):
Abstract The grid connection of a mass of distributed power sources in the AC/DC hybrid micro-grid will cause harmonics, voltage sags, voltage fluctuations, and flicker in the grid, which seriously affects the power quality of the grid. Therefore, the power quality problems such as the resonance generated by the AC/DC hybrid micro-grid need to be studied urgently. In this paper, a resonance detection technology based on the combination of wavelet transform (WT) and fast Fourier transform (FFT) is proposed. This method uses wavelet transform to process the high-frequency and low-frequency parts of the signal separately, and eliminates part of the interference signal. The method then uses the FFT to obtain the resonance content. The AC/DC hybrid micro-grid resonance detection method based on WT and FFT can not only determine the time and amplitude of the resonance signal, but also filter the interference signal and improve the accuracy of frequency domain analysis. It is verified by simulation that the algorithm can detect the resonance of the AC/DC hybrid micro-grid.
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Aljafari, Belqasem, Subramanian Vasantharaj, Vairavasundaram Indragandhi e Rhanganath Vaibhav. "Optimization of DC, AC, and Hybrid AC/DC Microgrid-Based IoT Systems: A Review". Energies 15, n. 18 (18 settembre 2022): 6813. http://dx.doi.org/10.3390/en15186813.
Testo completoAbstract (sommario):
Smart microgrids, as the foundations of the future smart grid, combine distinct Internet of Things (IoT) designs and technologies for applications that are designed to create, regulate, monitor, and protect the microgrid (MG), particularly as the IoT develops and evolves on a daily basis. A smart MG is a small grid that may operate individually or in tandem with the electric grid, and it is ideal for institutional, commercial, and industrial consumers, as well as urban and rural societies. A MG can operate in two methods (stand-alone and grid-connected), with the ability to transition between modes due to local grid faults, planned maintenance, expansions, deficits and failures in the host system, and other factors. Energy storage is the process of storing and converting energy that can be used for a variety of purposes, including voltage and frequency management, power backup, and cost optimization. IoT is designed to deliver solutions for optimal energy management, security protocols, control methods, and applications in the MG, with numerous distributed energy resources (DER) and interconnected loads. The use of IoT architecture for MG operations and controls is discussed in this research. With the use of power grid equipment and IoT-enabled technology, MGs are enabling local networks to give additional services on top of the essential supply of electricity to local networks that operate simultaneously or independently from the regional grid. Additionally, this review shows how hybrid AC/DC MGs are advantageous compared to AC and DC MGs. The state-of-the-art optimization techniques and trends in hybrid MG research are included in this work.
18
Luo, Yi, Yin Zhang, Muyi Tang, Youbin Zhou, Ying Wang, Defu Cai, Haiguang Liu, Ding Li, Yaning Wu e Yue Han. "A Planning Method of Hybrid AC/DC Receiving End Grid with Mutually Exclusive Constraints". E3S Web of Conferences 256 (2021): 01036. http://dx.doi.org/10.1051/e3sconf/202125601036.
Testo completoAbstract (sommario):
With the large-scale application of LCC-HVDC and VSC-HVDC in power systems, the mutually exclusive constraints (MES) appear in the optimal planning of hybrid AC/DC receiving end power grid. The MES increase the scale of the construction set of substations and the transmission lines and decrease the planning efficiency and effectiveness of the conventional method. This paper proposes a novel hybrid AC/DC receiving end grid planning method with MES. Constraint satisfaction problem (CSP) is utilized to model the set of mutually exclusive selected lines, in which mutually exclusive candidate lines are converted to mutually exclusive variables and then introduced into the planning model as constraints. After establishing the hybrid AC/DC receiving end grid planning model with MES, the backtracking search algorithm (BSA) is used to solve the optimal planning. The effectiveness of the proposed hybrid AC/DC power grid planning method with MES is verified by case studies.
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Wang, Zonghao, e Liying Sun. "Design of voltage stabilizing control for a hybrid microgrid with state constraints based on the switching system". Journal of Physics: Conference Series 2474, n. 1 (1 aprile 2023): 012067. http://dx.doi.org/10.1088/1742-6596/2474/1/012067.
Testo completoAbstract (sommario):
Abstract With the application and development of new energy generation technology and distributed power supply system, AC-DC hybrid microgrid has the comprehensive advantages of AC microgrid and DC microgrid, and it is significant to study the voltage stability of hybrid microgrid. Based on the switching system theory, the voltage stability control of the ac-dc hybrid micro-grid in grid-connected and the off-grid operation mode are studied in this paper. Considering that the AC and DC bus voltages of the microgrid are constrained in practical engineering applications, the Backstepping controller is designed by using the barrier Lyapunov function and Backstepping method. Considering that the equivalent resistance in the system can not be accurately measured and combined with adaptive control, it is more practical for practical engineering applications.
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Xu, Xiao, Xiao Chun Ma, Zhen Ning Zi, Bao Qiang Ben, Hua Li e Si Ming Wei. "Research on Electric Power Control Technique for Stable Operation of DC Micro-Grid". Advanced Materials Research 986-987 (luglio 2014): 1129–33. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1129.
Testo completoAbstract (sommario):
Distributed generation (DG) into DC micro-grid can save a lot of converter equipments compared with AC micro-grid,.So,with the popularity of DG,DC micro-grid technology also has get great development.However,the key technology of DC micro-grid is not yet mature.This paper is based on shanghai DC micro-grid demonstration project of Sate Grid Smart Grid Research Institute.Firstly,we analysis the advantages and disadvantages of AC,DC and AC/DC hybrid micro-grid.Then, after comparison and analysis of DC micro-grid topology,we put forward system scheme and corresponding control strategy.The simulation results show that, the proposed control strategy is feasible,simple,real-time and effective.This design scheme is applicable for radiant topology and would provide guidance to the development direction of DC micro-grid project later.
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Sang, Zi-xia, Reng-cun Fang, He Lei, Dong-jun Yang, Zhu Chen e Jiong Yan. "Fault Characteristic Analysis of Single-Phase Grounding Fault in AC grid of Energy Router in Interacted and Interconnected Micro Grid". E3S Web of Conferences 233 (2021): 01046. http://dx.doi.org/10.1051/e3sconf/202123301046.
Testo completoAbstract (sommario):
The energy router composed of double active bridge (DAB) can interconnect multiple voltage level AC distribution network through DC lines to form AC/DC hybrid distribution network. The fault types of the system are diverse and the fault characteristics are complex. This paper studies the fault characteristics of the system in detail. The single-phase grounding fault of AC network side and single-phase grounding fault of AC valve side occurred in the system. This paper explored the impact of the AC side of the system after the above failure, and make a detailed comparative analysis. The results show that DAB can isolate the influence of AC side fault, and provide theoretical basis for the selection of grounding mode and the design of protection system for AC/DC hybrid distribution network.
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Peña-Carro, Paula, e Oscar Izquierdo-Monge. "Hybrid AC/DC architecture in the CE.D.E.R.-CIEMAT microgrid: demonstration of the TIGON project". Open Research Europe 2 (26 ottobre 2022): 123. http://dx.doi.org/10.12688/openreseurope.15154.1.
Testo completoAbstract (sommario):
This article presents the demonstrative development of the Towards Intelligent DC-based hybrid Grids Optimizing the Network performance (TIGON) project at the Centre for the Development of Renewable Energy - Centre for Energy, Environmental and Technological Research (CE.D.E.R.-CIEMAT), as well as the established objectives to be achieved with the implementation of a microgrid with smart grid architecture based on direct current (DC) and integrated into the current energy system. This type of architecture is proposed as a future solution to reduce energy losses caused by DC-alternating current (AC) conversions, increasing the overall performance and profitability of hybrid grids. All this without forgetting to ensure the supply, stability and reliability of the system with the development of all the necessary equipment and protections to make this approach a reality. The microgrid design and process of implementation start from a transformation centre, from which the medium voltage direct current (MVDC) grid will be created by the solid-state transformer (SST). In the MVDC grid, we will find a bank of lead-acid batteries and other essential equipment in the microgrid, a DC/DC converter that will create the low voltage direct current (LVDC) grid. On the LVDC side, several branches have been designed to connect the rest of the systems: generation (mini-wind and photovoltaic), storage (lithium ferro-phosphate [LFP] batteries) and loads (AC and DC loads). Each of the equipment will have a connection to the DC grid through converters made exclusively for this equipment and connexion to the AC grid, which will allow us to obtain all the necessary data to carry out the required studies to achieve the established objectives of the project.
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Peña-Carro, Paula, e Oscar Izquierdo-Monge. "Hybrid AC/DC architecture in the CE.D.E.R.-CIEMAT microgrid: demonstration of the TIGON project". Open Research Europe 2 (9 gennaio 2024): 123. http://dx.doi.org/10.12688/openreseurope.15154.2.
Testo completoAbstract (sommario):
This article presents the demonstrative development of the Towards Intelligent DC-based hybrid Grids Optimizing the Network performance (TIGON) project at the Centre for the Development of Renewable Energy - Centre for Energy, Environmental and Technological Research (CE.D.E.R.-CIEMAT), as well as the established objectives to be achieved with the implementation of a microgrid with smart grid architecture based on direct current (DC) and integrated into the current energy system. This type of architecture is proposed as a future solution to reduce energy losses caused by DC-alternating current (AC) conversions, increasing the overall performance and profitability of hybrid grids. All this without forgetting to ensure the supply, stability and reliability of the system with the development of all the necessary equipment and protections to make this approach a reality. The microgrid design and process of implementation start from a transformation centre, from which the medium voltage direct current (MVDC) grid will be created by the Solid State Transformer (SST). In the MVDC grid, we will find a bank of lead-acid batteries and other essential equipment in the microgrid, a DC/DC converter that will create the low voltage direct current (LVDC) grid. On the LVDC side, several branches have been designed to connect the rest of the systems; generation (mini-wind and photovoltaic), storage (LFP batteries) and loads (AC and DC loads). Each of the equipment will have a connection to the DC grid through converters made exclusively for this equipment and connexion to the AC grid, which will allow us to obtain all the necessary data to carry out the required studies to achieve the established objectives of the project.
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Dhumal, S. D., e Dr P. V. Paratwar. "Estimating the Stability of an AC-DC Hybrid Micro Grid with Multilayer Power Flow While Using Interconnected Converter". International Journal for Research in Applied Science and Engineering Technology 11, n. 6 (30 giugno 2023): 1615–22. http://dx.doi.org/10.22214/ijraset.2023.52662.
Testo completoAbstract (sommario):
Abstract: Regionalized networks, also known as micro grids, must be able to operate independently by cutting off their connection to the main grid in order for a system to stay stable. Customers' reliability can be raised by providing a more robust power supply. Due to reversed energy flow from distributed generator units, regional fluctuations, temporary micro grid modes, significant frequency discrepancies in electrically isolated mode operation, as well as financial and supply demand uncertainties, consistency, dependability, and security are in fact the main problems with micro grids. The system is more unstable when electrical energy is transmitted from the AC side to the DC side and from the DC side to the AC side, despite the fact that strengthening the stability of the hybrid micro grid is their main objective. Therefore, a variety of circuit breakers, buck boost converters, grid bidirectional converters, and intermediate IC (Interlinking converter) are utilized to preserve the stability of the hybrid micro grid. This article explains how to build a bidirectional power flow through an interactive converter using stability evaluation using MATLAB. Simulation may improve the circuit's performance for the best outcomes achievable. The most stable hybrid micro grid findings were shown. An interlinking converter is utilized in this work to improve micro grid stability while power is flowing via the AC and DC grids in both directions. The findings might be acquired using a MATLAB simulation. This method also has the advantage of reducing the amount of time needed for the system to stabilize. Consequently, the system will be more dependable and will provide excellent supplies.
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Jiang, Runhui, e Weimin Wu. "A new AC/DC converter with three-bus output and controllable DC link short-circuit current". Journal of Physics: Conference Series 2823, n. 1 (1 agosto 2024): 012047. http://dx.doi.org/10.1088/1742-6596/2823/1/012047.
Testo completoAbstract (sommario):
Abstract In the AC/DC hybrid microgrid, single-phase AC/DC converters play a vital role in maintaining the energy balance of the AC grid and DC grid. The industry usually uses large electrolytic capacitors to absorb the secondary ripple power. However, it produces a larger short-circuit current. This paper proposes a three-bus output AC/DC converter that can limit the short-circuit current. The feasibility of steady-state operation and the ability of transient processes to limit short-circuit current was verified.
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Mohammadi, Fazel, Gholam-Abbas Nazri e Mehrdad Saif. "An Improved Mixed AC/DC Power Flow Algorithm in Hybrid AC/DC Grids with MT-HVDC Systems". Applied Sciences 10, n. 1 (31 dicembre 2019): 297. http://dx.doi.org/10.3390/app10010297.
Testo completoAbstract (sommario):
One of the major challenges on large-scale Multi-Terminal High Voltage Direct Current (MT-HVDC) systems is the steady-state interaction of the hybrid AC/DC grids to achieve an accurate Power Flow (PF) solution. In PF control of MT-HVDC systems, different operational constraints, such as the voltage range, voltage operating region, Total Transfer Capability (TTC), transmission reliability margin, converter station power rating, etc. should be considered. Moreover, due to the nonlinear behavior of MT-HVDC systems, any changes (contingencies and/or faults) in the operating conditions lead to a significant change in the stability margin of the entire or several areas of the hybrid AC/DC grids. As a result, the system should continue operating within the acceptable limits and deliver power to the non-faulted sections. In order to analyze the steady-state interaction of the large-scale MT-HVDC systems, an improved mixed AC/DC PF algorithm for hybrid AC/DC grids with MT-HVDC systems considering the operational constraints is developed in this paper. To demonstrate the performance of the mixed AC/DC PF algorithm, a five-bus AC grid with a three-bus MT-HVDC system and the modified IEEE 39-bus test system with two four-bus MT-HVDC systems (in two different areas) are simulated in MATLAB software and different cases are investigated. The obtained results show the accuracy, robustness, and effectiveness of the improved mixed AC/DC PF algorithm for operation and planning studies of the hybrid A/DC grids.
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Hong, Yuan Xin, e Guang Qing Bao. "Emergency Power Support and Voltage Stability Analysis of the AC/DC Hybrid Transmission System". Advanced Materials Research 614-615 (dicembre 2012): 1033–37. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.1033.
Testo completoAbstract (sommario):
With the completion of Three Gorges Project, the power system in China is forming a huge AC/DC network. In the hybrid AC/DC parallel transmission system, a line fault will cause fluctuations even crash of the system. The HVDC transmission system based on the emergency DC power support (EDCPS) can provide a fast emergency power support for the interconnected AC power grid flexibly and improve the stability of AC power. A model of AC/DC hybrid transmission system is established in the PSCAD/EMTDC simulation environment. An improved PID controller is firstly introduced to the hybrid AC/DC transmission system. The simulation result shows the EDCPS has an obvious effect on keeping the voltage stability of the system.
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Taleb, Maamar, Mohamed Amine Fnaiech e Khaled Zehar. "An Enhanced Hybrid Grid Connected Photovoltaic System Using Voltage Oriented Controller and Class D Chopper". Renewable Energy and Power Quality Journal 21, n. 1 (luglio 2023): 69–75. http://dx.doi.org/10.24084/repqj21.225.
Testo completoAbstract (sommario):
The performance of a shunt interconnection made from a PV system, a three phase grid voltage supply, and a DC shunt motor (DC load) is investigated The PV system participates with maximum powers to the overall interconnection active power flow. It uses a class D chopper circuitry controlled properly by a typical maximum power point tracker (MPPT) controller. The grid has the role of supplying active power in case of any power deficiency needed by the DC motor load. Similarly, it has also the role of absorbing active power in case of any additional power generated by the PV system and not needed by the DC load. This is done by using an AC/DC power electronic converter. The AC/DC power electronic converter operates either under rectifier or inverter modes. The AC/DC power electronic converter is also operated under the next two conditions: 1-the reactive power expected at the grid voltage bus should be nearly null, 2-harmonics currents often encountered in the grid line currents waveforms should be tolerable. The two latter conditions are fulfilled by using the principle of voltage oriented control (VOC) technique. The performance of the investigated interconnection is simulated in Matlab/Simulink platform. Quite satisfactory results are obtained. The satisfaction about the obtained simulation results persists on being able to integrate easily the PV system with the AC grid while extracting maximum power from the PVG and having a unity power factor at the AC grid bus and less encountered harmonics in the ac line currents.
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Vinothkumar, J., e R. Thamizhselvan. "Efficient Power Management and Control Strategy of Hybrid Renewable Energy System in Microgrid". International Journal on Applied Physics and Engineering 2 (17 luglio 2023): 106–27. http://dx.doi.org/10.37394/232030.2023.2.11.
Testo completoAbstract (sommario):
Currently, the use of renewable energy has gradually increased due to the environmental problems present nowadays. The intermittency of distributed renewable generation poses significant challenges for the operation and integration of microgrids. Unlike the main power grid, where load balancing resources, in general, are abundant, the balancing of generation and load in a microgrid must be done by small gas turbines, diesel generators, or energy storage devices with very limited capacity and at much higher costs. Consequently, the proposed methodology seeks a model for minimizing the Energy Cost (EC) and enhancing the power supply for rural areas by designing and analyzing four different hybrid system configurations based on integrating a biomass system with a photovoltaic (PV), wind turbine (WT) and battery system. To ensure the desired power demand with minimum production cost, the research proposed an energy-efficient Hybrid DC/AC microgrid using four renewable energy sources. Lithium-ion batteries were chosen for this study due to their high energy density, long life cycle, and high efficiency. The existence of both AC and DC microgrids has led to a new concept of hybrid AC/DC microgrids which consists of both AC and DC grids tied by an Interlinking Converter (ILC). It comprises a DC grid and AC grid interlinked by a bidirectional DC/AC converter. Such a hybrid AC/DC microgrid has the advantages of both AC and DC with increased efficiency and less cost. To provide higher voltages, the Multi-Input Booster (MIB) DC-DC converters are used as a power converter in between load and source to enforce and increase the PV depending on the voltage output signal. Further extract maximum power from the solar PV system, perturb and observe algorithm-based power point tracking control mechanism is proposed DC link voltage of ILC is regulated usually by DC side control in load sharing among sources in the DC microgrid. In addition, to overcome the load fluctuation problem in a microgrid, the research introduced a Mamdani type 2 PID-fuzzy controller. Performance index parameters of the transient response characteristics are also improved by using the proposed control approach. The time-domain dynamic responses reveal that the proposed type-II fuzzy PID controller can balance the power generation and demand properly and control both system frequency and tie-line power effectively.
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Zhang, Junli, Guoteng Wang, Zheng Xu e Zheren Zhang. "A Comprehensive Evaluation Method and Strengthening Measures for AC/DC Hybrid Power Grids". Energies 15, n. 12 (17 giugno 2022): 4432. http://dx.doi.org/10.3390/en15124432.
Testo completoAbstract (sommario):
Due to the complex operation characteristics of AC/DC hybrid power grids, it is a great challenge to comprehensively evaluate their stability and formulate appropriate strengthening schemes for them. To address this challenge, the following studies are carried out in this paper. First, an evaluation system including six indicators is established for AC/DC hybrid power grids. Next, aiming at the problems that may be revealed by the comprehensive evaluation, strengthening measures that can be utilized are introduced. Then, a comprehensive evaluation method for AC/DC hybrid power grids and their potential strengthening schemes is proposed. This method can deal with three issues, including normalization of the indicators, weighting of the indicators, and the trade-off of technology and cost. Finally, in the case study of the Qujing Power Grid, the main problems faced by regional power grids are pointed out, and four feasible strengthening schemes are formulated and evaluated.
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Razzaq, Syed Abdul, e Vairavasamy Jayasankar. "Autonomous power sharing for AC/DC HMGS using decentralized modified droop method for interlinking converter". International Journal of Power Electronics and Drive Systems (IJPEDS) 13, n. 4 (1 dicembre 2022): 2139. http://dx.doi.org/10.11591/ijpeds.v13.i4.pp2139-2147.
Testo completoAbstract (sommario):
<p>The present trend of integrating renewable energy sources (RES) in AC/DC hybrid micro grid systems (HMGS) has certainly reduced the greenhouse gases and provides the variety of power sources for micro grid (MG). Interlinking converter (ILC) is the main converter for interconnecting AC/DC sub-grids with a variety of features like autonomous bidirectional power sharing, reducing the power conversions in the grid and additionally a featuring aspect for energy management system (EMS). Interlinking converters are desired to maintain stable frequency, constant voltages at buses, reduce the power losses, reduce switching losses and control on circulating currents, most of the control methods could not achieve all. In this paper, the decentralized modified droop control method is presented which is significant in meeting the autonomous bidirectional AC/DC power load demand and in achieving the desired features. A three coordinated model is proposed where AC frequency, ILC power and DC voltage are the corresponding axis. The power sharing through the ILC is dependent on the AC frequency droop and DC voltage droop which occurs due to overloading. This control scheme is compatible for interconnection with multi-port grids. This control schemes provide more reliable, stable and accurate results compare to conventional droop methods.</p>
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Rao, T. Jagan Mohana. "DESIGNING OF DC GRID SOLAR-WIND HYBRID POWER GENERATION SYSTEM". INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, n. 04 (17 aprile 2024): 1–5. http://dx.doi.org/10.55041/ijsrem30345.
Testo completoAbstract (sommario):
Our project's main goal is to create a prototype hybrid renewable energy system that mixes solar and wind power. The system's goal is to directly feed energy from the turbine and solar panels into the DC grid. An inverter is also integrated to provide AC power. Our strategy emphasizes efficiency and simplicity by acquiring both AC and DC electricity from the project. Utilizing the complementing qualities of solar and wind energy, we want to develop a dependable and sustainable power generation system. We hope to show that combining renewable energy sources and maximizing energy output for both AC and DC applications is feasible with this creative design. Key Words: Dc grid, solar power generation, wind power generation, batteries, hybrid power generation
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Estabragh, Mohsen Rezaie, Ali Dastfan e Morteza Rahimiyan. "Grid-Tied Hybrid AC-DC Microgrid: Finding Optimal Number of Parallel-Connected AC-DC Bidirectional Interfacing Converters". International Transactions on Electrical Energy Systems 2022 (2 giugno 2022): 1–14. http://dx.doi.org/10.1155/2022/1932818.
Testo completoAbstract (sommario):
Linking AC and DC microgrids via a bidirectional AC-DC interfacing converter has emerged the hybrid AC-DC microgrid. The DC bus is connected to the grid by a series converter to mitigate the grid voltage’s power quality problems. To enhance the reliability and to increase transferring active and nonactive powers between DC and AC main buses, the AC-DC bidirectional interfacing converters are connected in parallel. In this paper, the optimal number (n) of parallel-connected bidirectional interfacing converters is obtained to minimize the annual cost of investment and the reliability cost. A two-step deciding algorithm is proposed to find n. First, active and nonactive powers between DC and AC buses are obtained with power quality and power flow considerations. Based on two types of powers, two reliability indices are calculated, including the expected energy shortage (EES) based on active power and the expected Volt-Amps shortage (EVAS) based on nonactive power. The sum of two reliability index costs is considered as the reliability cost. Next, a decision-making strategy is executed to determine the optimal n by making a trade-off between minimization of two objectives: the annual cost of investment and the reliability cost. The simulations of a grid-tied hybrid AC-DC microgrid are done with the experimental measurement data of DC and AC loads and distributed generations. Simulation results verify the performance of the represented approach.
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Jayaram, Jayachandran, Malathi Srinivasan, Natarajan Prabaharan e Tomonobu Senjyu. "Design of Decentralized Hybrid Microgrid Integrating Multiple Renewable Energy Sources with Power Quality Improvement". Sustainability 14, n. 13 (25 giugno 2022): 7777. http://dx.doi.org/10.3390/su14137777.
Testo completoAbstract (sommario):
Due to the energy crisis and exhaustion in the amount of fossil fuels left, there is an urge to increase the penetration of renewables in the grid. This paper deals with the design and control of a hybrid microgrid (HMG) in the presence of variable renewable energy sources. The DC sub-grid consists of a permanent magnet synchronous generator (PMSG) wind turbine, solar PV array with a perturb-and-observe (P&O) MPPT algorithm, boost converter, and battery energy storage system (BESS) with DC loads. The AC sub-grid consists of a PMSG wind turbine and a fuel cell with an inverter circuit synchronized to the grid to meet its load demand. A bidirectional interlinking converter (IC) connects the AC sub-grid and DC sub-grid, which facilitates power exchange between them. The decentralized control of converters allows all the renewables to operate in coordination independently without communication between them. The proposed control algorithm of the IC enables it to act as an active power filter in addition to the power exchange operation. The active power filtering feature of the IC helps to retain the power quality of the microgrid as per IEEE 519 standards by providing reactive power support and reducing the harmonic levels to less than 5%. The HMG with the proposed algorithm can operate in both grid-connected and islanded modes. While operating in grid-connected mode, power exchange between DC and AC sub-grids takes place and all the load demands are met. If it is in islanded mode, a diesel generator supports the AC sub-grid to meet the critical load demands and the BESS supports the DC microgrid. The proposed model is designed and simulated using MATLAB-SIMULINK and its results are analyzed. The efficacy of the proposed control is highlighted by comparing it with the existing controls and testing the HMG for load variations.
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Liu, Bei, Xu Shen, Ruosong Zhang, Haofei Chen e Xiaohang Zhou. "Joint Planning Method of Virtual Power Plant for Distributed Generation and Grid in AC-DC Medium and Low Voltage Distribution Network". Journal of Physics: Conference Series 2537, n. 1 (1 giugno 2023): 012021. http://dx.doi.org/10.1088/1742-6596/2537/1/012021.
Testo completoAbstract (sommario):
Abstract The high proportion of virtual power plants (VPPs) used for distributed generation may cause problems such as power fluctuations and voltage distribution. In contrast, AC/DC hybrid power grid has strong transmission capacity due to its power information transmission. However, Its power grid structure and the location and capacity of VPP have an impact on the consumption capacity of the system, and the relationship between them are closely coupled. In addition, Under different operation modes, power grids of different voltage levels also have great differences. Therefore, the cooperative planning of medium and low voltage AC and DC distribution networks can improve the transmission capacity of the power grid Further improve the ability of distribution network to consume distributed power, A method is proposed in this paper about siting and capacity determination and AC-DC distribution grid frame transformation planning for medium and low voltage systems. The upper-layer model mainly focuses on AC-DC transformation scheduling in the power grid, distributed node location in the access grid and transmission line transmission capacity, while the lower-layer model effectively communicates with the low-voltage system through information flow and changes the operation of the power grid to a certain extent.The results show that the distributed generation system can reduce the operation cost and improve the overall operation efficiency of the power grid.
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Monteiro, Vitor, e Joao L. Afonso. "The Future of Electrical Power Grids: A Direction Rooted in Power Electronics". Energies 16, n. 13 (25 giugno 2023): 4929. http://dx.doi.org/10.3390/en16134929.
Testo completoAbstract (sommario):
Electrical power grids are changing with a focus on ensuring energy sustainability and enhanced power quality for all sectors. Over the last few decades, there has been a change from a centralized to a decentralized paradigm, which is the consequence of a large-scale incorporation of new electrical technologies and resultant equipment. Considering the foreseeable continuation of changes in electrical power grids, a direction rooted in power electronics with a focus on hybrid AC/DC grids, including the support of solid-state transformers and unified systems, is presented in this paper. Converging on hybrid AC/DC grids, DC grids (structured as unipolar and bipolar) and coupled and decoupled AC configurations are analyzed. On the other hand, in the context of solid-state transformers, feasible structures are analyzed, including the establishment of hybrid AC/DC grids, and the assessment of gains for boosting power quality is presented. Unified power electronics systems are also of fundamental importance when contextualized within the framework of future power grids, presenting higher efficiency, lower power stages, and the possibility of multiple operations to support the main AC grid. In this paper, such subjects are discussed and contextualized within the framework of future power grids, encompassing highly important and modern structures and their associated challenges. Various situations are characterized, revealing a gradual integration of the cited technologies for future power grids, which are also known as smart grids.
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Lv, Zhaorui, e Ying Yang. "Design and analysis of relay protection system for AC DC hybrid system". E3S Web of Conferences 360 (2022): 01087. http://dx.doi.org/10.1051/e3sconf/202236001087.
Testo completoAbstract (sommario):
With the national new energy policy, AC DC integrated distribution network is more and more common, in the AC DC hybrid grid, the interaction between AC and DC side will lead to complicated fault characteristics, which further affect the relay protection system strategy, with typical system as the object of the AC DC relay protection strategy, fault characteristics aimed at different short dot simulation study are done, and verify the correctness and feasibility of the system configuration.
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Kuang, Cuizhe, Meng Xiao, Zexing Chen, Zehuai Liu, Ziqi Wang, Baoqiang Lv e Guoxin Li. "Fixed-frequency Current Control Method of Islanding Micro-grid Based on Improved Neural Network". International Journal on Artificial Intelligence Tools 29, n. 07n08 (30 novembre 2020): 2040017. http://dx.doi.org/10.1142/s0218213020400175.
Testo completoAbstract (sommario):
In the islanding micro-grid operation mode, due to the lack of support from the large power grid, the voltage of the bus and each node in the network is completely supported by the cooperation of the micro-grid inverters in the grid. Therefore, the control performance of the micro-grid inverter determines the quality of the power supply voltage. This paper proposes an improved AC and DC islanding micro-grid fixed frequency current control method with variable topology. First, the neural network algorithm improved by particle swarm optimization is used as the basis to optimize the coordinated compensation control of the micro-grid to obtain the fitness value of the objective function under the positive and negative sequence potentials. Then, a control strategy for the improved AC/DC hybrid micro-grid is proposed, and the decoupling and coordinated control strategy for the output compensation of the dual filters in the islanding mode is designed. Finally, simulations and experiments verify the improved AC/DC hybrid microgrid with variable topology and achieve the goal of constant-frequency current control.
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An, Byeong-Hyeon, Jae-Deok Park, Jun-Soo Che, Tae-Hun Kim e Tae-Sik Park. "Asynchronous AC-DC Hybrid Power Grid Connection System Using VFT". Journal of the Korean Institute of Illuminating and Electrical Installation Engineers 37, n. 2 (30 aprile 2023): 54–62. http://dx.doi.org/10.5207/jieie.2023.37.2.054.
Testo completo
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Ajbale, Shubham. "Study the Simulation of Hybrid Solar Wind Charging Station". International Journal for Research in Applied Science and Engineering Technology 9, n. VI (30 giugno 2021): 5275–78. http://dx.doi.org/10.22214/ijraset.2021.36193.
Testo completoAbstract (sommario):
Electric vehicles play a vital role in energy saving and emission reduction of harmful greenhouse gases. electrical vehicles dispersion into the vehicles market has not been up to the mark because of less value effective and these vehicles have to be compelled to be compelled to recharge once in sixty five to seventy klick drive. The novel hybrid vehicle charging station carries with it fully totally different sources like PV systems, wind systems, the AC provide, batteries area unit used as a main energy storage system, kind DC little grid permanently energy delivery. Thus, grid offers decent quality of power to 3 totally different hundreds notably 110-volt AC single-phase output ,100 v DC output. The grid is at 230 V rms with fifty cps connected isolator in relation to the DC bus. The three-part output of the grid is regenerated to the rippled DC by utilization of DBR (Diode Bridge Rectifier). The regenerated DC voltage is fed to graphic symbol device that might be a DC-DC devices, making the rippled DC to constant DC with the use of a buck device, this paper justifies comparative performance hybrid charging station mistreatment buck and letter convertor to stabilize the DC voltage. planned system analysis in MATLAB Simulink.
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Chen, Ye, Qiongqian Yang, Zhenting Li, Mengmeng Liu, Jianfeng Zhang e Yang Pan. "Risk Assessment for Alternating Current / Direct Current (AC/DC) Hybrid Systems with Renewables Penetration". Journal of Physics: Conference Series 2109, n. 1 (1 novembre 2021): 012002. http://dx.doi.org/10.1088/1742-6596/2109/1/012002.
Testo completoAbstract (sommario):
Abstract In this paper, a risk assessment method is proposed for AC/DC hybrid systems with renewables penetration, considering the effect of renewables penetration and the application of DC transmission. The sequential Monte Carlo method is introduced to simulate the output of renewables generators, and the unified iterative method is used to solve the problem of AC/DC hybrid system power flow calculation. By establishing the quantized risk assessment indices, the risk of AC/DC hybrid systems with renewables penetration can be analysed. The results of EPRI of China 6-machine-22-bus Test case show that the proposed method can effectively evaluate the risk level of AC/DC hybrid systems with renewable energy penetration and provide reference for power grid planning and the actual operation in advance.
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Dai, Wei, Yang Gao, Hui Hwang Goh, Jiangyi Jian, Zhihong Zeng e Yuelin Liu. "A Non-Iterative Coordinated Scheduling Method for a AC-DC Hybrid Distribution Network Based on a Projection of the Feasible Region of Tie Line Transmission Power". Energies 17, n. 6 (18 marzo 2024): 1462. http://dx.doi.org/10.3390/en17061462.
Testo completoAbstract (sommario):
AC-DC hybrid distribution grids realize power transmission through tie lines. Accurately characterizing the power exchange capacity between regional grids while ensuring safe grid operation is the basis for the coordinated scheduling of resources in interconnected distribution grids. However, most of the current AC/DC hybrid models are linear, and it is challenging to ensure the accuracy criteria of the obtained feasible regions. In this paper, a two-stage multi-segment boundary approximation method is proposed to characterize the feasible region of hybrid distribution grid tie line operation. Information such as security operation constraints are mapped to the feasible region of the boundary tie line to accurately characterize the transmission exchange capacity of the tie line. To avoid the limitations of linear models, the method uses a nonlinear model to iteratively search for boundary points of the feasible region. This ensures high accuracy in approximating the real feasible region shape and capacity limitations. A convolutional neural network (CNN) is then utilized to map the given boundary and cost information to obtain an estimated equivalent operating cost function for the contact line, overcoming the inability of previous methods to capture nonlinear cost relationships. This provides the necessary cost information in a data-driven manner for the economic dispatch of hybrid AC-DC distribution networks. Numerical tests demonstrate the effectiveness of the method in improving coordination accuracy while preserving regional grid privacy. The key innovations are nonlinear modeling of the feasible domain of the contact line and nonlinear cost fitting for high-accuracy dispatch.
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Rauf, Shoaib, e Nasrullah Khan. "Application of DC-AC Hybrid Grid and Solar Photovoltaic Generation with Battery Storage Using Smart Grid". International Journal of Photoenergy 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/6736928.
Testo completoAbstract (sommario):
Smart grid for the past few years has been the prime focus of research in power systems. The aim is to eliminate load shedding and problematic blackout conditions, further offering cheap and continuous supply of electricity for both large and small consumers. Another benefit is to integrate renewable energy resources with existing dump grid in more efficient and cost-effective manner. In past few years, growing demand for sustainable energy increases the consumption of solar PV. Since generation from solar PV is in DC and most of the appliances at home could be operated on DC, AC-DC hybrid distribution system with energy management system is proposed in this paper. EMS helps to shift or control the auxiliary load and compel the users to operate specific load at certain time slots. These techniques further help to manage the excessive load during peak and off peak hours. It demonstrates the practical implementation of DC-AC network with integration of solar PV and battery storage with existing infrastructure. The results show a remarkable improvement using hybrid AC-DC framework in terms of reliability and efficiency. All this functioning together enhances the overall efficiency; hence, a secure, economical, reliable, and intelligent system leads to a smart grid.
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Chang, Fangyuan, John O’Donnell e Wencong Su. "Voltage Stability Assessment of AC/DC Hybrid Microgrid". Energies 16, n. 1 (29 dicembre 2022): 399. http://dx.doi.org/10.3390/en16010399.
Testo completoAbstract (sommario):
AC/DC hybrid microgrids are becoming potentially more attractive due to the proliferation of renewable energy sources, such as photovoltaic generation, battery energy storage systems, and wind turbines. The collaboration of AC sub-microgrids and DC sub-microgrids improves operational efficiency when multiple types of power generators and loads coexist at the power distribution level. However, the voltage stability analysis and software validation of AC/DC hybrid microgrids is a critical concern, especially with the increasing adoption of power electronic devices and various types of power generation. In this manuscript, we investigate the modeling of AC/DC hybrid microgrids with grid-forming and grid-following power converters. We propose a rapid simulation technique to reduce the simulation runtime with acceptable errors. Moreover, we discuss the stability of hybrid microgrids with different types of faults and power mismatches. In particular, we examine the voltage nadir to evaluate the transient stability of the hybrid microgrid. We also design a droop controller to regulate the power flow and alleviate voltage instability. During our study, we establish a Simulink-based simulation platform for operational analysis of the microgrid.
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Jiang, Ke, Feng Wu, Linjun Shi e Keman Lin. "Distributed Hierarchical Consensus-Based Economic Dispatch for Isolated AC/DC Hybrid Microgrid". Energies 13, n. 12 (20 giugno 2020): 3209. http://dx.doi.org/10.3390/en13123209.
Testo completoAbstract (sommario):
In this paper, a distributed hierarchical consensus algorithm is proposed to solve the economic dispatch (ED) problem for the isolated AC/DC hybrid microgrid. At first, the whole nodes of the AC/DC hybrid microgrid are divided into two parts, that is, the leadership layer nodes and the tracking layer nodes. The leadership layer nodes update the data through their own feedback elements, while the tracking layer nodes receive the information from the leadership layer nodes and update the data. After several iterations, the two different layer nodes obtain the same state, which realizes the dynamic active power balance of the whole AC/DC microgrid. Besides, the AC sub-grid and DC sub-grid can also realize the power balance by the proposed algorithm, and the energy storage units will absorb or release active power to meet the power demand in the respective section. In addition, the constraints of the nodes are also taken into account to guarantee that the power nodes in the AC/DC hybrid microgrid should operate within their own limitations, which is necessary to realize the ED for the considered hybrid microgrid. Finally, case study and simulation results are provided to illustrate the effectiveness of the proposed hierarchal method.
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Vinodini Bhole. "Augmented SPWM based Hybrid Output Converter for Renewable Energy and Nano-Grid Application". Journal of Electrical Systems 20, n. 3 (27 maggio 2024): 2072–88. http://dx.doi.org/10.52783/jes.4007.
Testo completoAbstract (sommario):
This study suggests a novel Augmented Sine PWM(ASPWM) based Hybrid Output Converter that can concurrently power AC and DC loads. Two boost converters are used in this configuration, and the AC voltage is the differential voltage tapped between the two source nodes (of the MOSFETs) of the individual converters. This converter plays a different role in providing power to AC and DC loads than conventional boost converter. Conventional boost requires a minimum of two stages to step up output DC voltage and inverter stage to convert DC to AC power. This novel hybrid output converter (HOC) skips all stages of boosting the output voltage and next stage of inverter also. HOC consists of two boost converts pumped by two VM(voltage multiplier) stages to get high voltage DC output. This HOC has two inputs, supplied by renewable like solar PV cells and has two outputs to supply AC and DC loads simultaneously. This dual input HOC integrates two renewable inputs for standalone nano grid application. The principle of operation of HOC is augmented sinusoidal pulse width modulation with AC reference signal is shifted by 1800for individual boost converter and augmented by dc offset. The circuit has been extensively simulated in PSIM’22 Matlab Simulink and an experimental prototype of 110W is tested in the laboratory.
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Fu, Hong Jun, Jian Hua Sun, Jing Gang Wang e Yang Yu Hu. "The Static Voltage Stability Limit Calculation of AC/DC Hybrid Power System Based on Improved Continuation Power Flow Algorithm". Applied Mechanics and Materials 347-350 (agosto 2013): 1450–54. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1450.
Testo completoAbstract (sommario):
With the HVDC system interconnected to power grid, the voltage stability problem of power grid has become increasingly prominent. This paper establishes the mathematical model of AC/DC hybrid power system and proposed an improved Continuation Power Flow (CPF) algorithm to calculate the static voltage stability limit of AC/DC hybrid system, the characteristics of this algorithm are as following: PQ decoupled power flow algorithm is used; Lagrange quadric interpolation is used in the process of predictor and step control; local parameter method is used in the correction. The iterations of AC/DC calculation alternate to solve power flow equations and select the step control near the critical power limit points to ensure the convergence of power flow solution. In order to verify the correctness of the proposed algorithm, this paper compares the calculation results by the improved algorithm and Matpower on the IEEE 14 bus-system. This paper calculates the static voltage stability limit of AC/DC hybrid power system under different DC control patterns of modified IEEE 14 bus-system and analyzes the impacts of different DC control pattern to the system voltage stability.
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El Azzab, Abdelfattah, Abdelmounime El Magri, Rachid Lajouad, Ilyass El Myasse, Aziz Watil e Hassan Ouabi. "Gym’s hybrid system for off-grid renewable energy solutions". Indonesian Journal of Electrical Engineering and Computer Science 33, n. 3 (1 marzo 2024): 1378. http://dx.doi.org/10.11591/ijeecs.v33.i3.pp1378-1386.
Testo completoAbstract (sommario):
<p>The primary objectives behind transitioning from fossil fuels to green energy sources, with a particular focus on reducing both electricity costs and carbon emissions. This transition has prompted various sectors and sports bikes, to embrace renewable energy alternatives, with a specific emphasis on technologies such as photovoltaic systems, energy storage solutions, and power generation from machines. The core subject of investigation in this paper is the application of renewable energy sources within sports bikes, with a particular emphasis on a hybrid system. This hybrid system incorporates DC/DC, AC/DC, and DC/AC converters to meet the energy requirements of the facility. The central aim of the research is to identify the most economically efficient scale for a self-sufficient hybrid photovoltaic system that integrates stationary generators and battery storage. The research seeks to optimize the balance between cost-effectiveness and sustainable energy provision in the context of sports facilities.</p>
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Xing, Zuo Xia, Guan Feng Zhang, Jin Song Liu e Xing Jia Yao. "Hybrid Energy Storage System to Stabilize the Power Fluctuation of Wind Power". Advanced Materials Research 608-609 (dicembre 2012): 487–93. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.487.
Testo completoAbstract (sommario):
Since distributed power generation equipment such as wind power contain electric power fluctuation connected into the power grid, hybrid energy storage (HESS) equipment for power compensation is used to solve the problems of reliability and operation of the utility power grid. Constant power control and Fuzzy-Rules-based control of AC-DC and BESS is proposed for smoothing the random wind power fluctuations, considering the operating constraints of the HESS, such as state of charge (SOC) and wind power (Pout). The simulation is accomplished by using a 9MW wind farm and the HESS in Matlab, The results show that by the proposed control methods of the bi-directional DC-DC converter and the DC-AC converter, the energy storage system can smooth the wind power outputs and provide reactive power support to the grid.
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Ray, Ishita. "Review of Impedance-Based Analysis Methods Applied to Grid-Forming Inverters in Inverter-Dominated Grids". Energies 14, n. 9 (7 maggio 2021): 2686. http://dx.doi.org/10.3390/en14092686.
Testo completoAbstract (sommario):
As the use of distributed generation with power electronics-based interfaces increases, the separation between DC and AC parts of the grid is reduced. In such inverter-dominated AC grids, impedance-based analysis methods are proving to be more powerful than traditional state-space-based analysis methods. Even the conventional parameters and standards used to estimate the stability of generators and stronger grids cannot fully capture the dynamics of weaker, inverter-dominated grids. It then stands to reason that system impedances that are commonly used to analyze DC systems will be useful in the analysis of grid-forming inverters in these hybrid systems. To understand the value of studying the impedances of inverters and other elements in weak AC grids, this article reviews and describes the various ways in which impedance-based analyses can be used to define, assess, and improve the performance of grid-forming inverter controllers. An exemplary case using the conventional P-f/Q-V droop control demonstrates the application of impedance-based analyses to determine the impact of the controller on the input and output stability of the inverter.