期刊文献+
共找到77篇文章
< 1 2 4 >
每页显示 20 50 100
Broadband and efficient second harmonic generation in LiNbO_(3)-LiTaO_(3) composite ridge waveguides at telecom-band
1
作者 Xin-Tong Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第1期256-261,共6页
Broadband nonlinear frequency conversions of optical waves are widely employed in multiple areas of optics and photonics. However, the broadening of conversion bandwidth is often at a cost of reduction in efficiency, ... Broadband nonlinear frequency conversions of optical waves are widely employed in multiple areas of optics and photonics. However, the broadening of conversion bandwidth is often at a cost of reduction in efficiency, which may induce a limitation on practical applications. Here we theoretically propose a novel design of LiNbO_(3) ridge waveguides on LiTaO_(3) substrates which can be used for efficient and broadband second harmonic generation. Through group velocity engineering of the ridge waveguides, acceptance bandwidth over 20 nm with a high conversion efficiency of > 25%W^(-1)·cm^(-2) is achieved at telecom-band. 展开更多
关键词 second harmonic generation lithium niobate ridge waveguide dispersion manipulation
下载PDF
Development,characterization and solubility enhancement of comparative dissolution study of second generation of solid dispersions and microspheres for poorly water soluble drug
2
作者 Poovi Ganesan Rajpriyadarsini Soundararajan +1 位作者 Uma Shanmugam Vinothini Ramu 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2015年第5期433-441,共9页
The poor dissolution characteristics of water-insoluble drugs are a major challenge for pharmaceutical scientists.Reduction of the particle size/increase in the surface area of the drug is a widely used and relatively... The poor dissolution characteristics of water-insoluble drugs are a major challenge for pharmaceutical scientists.Reduction of the particle size/increase in the surface area of the drug is a widely used and relatively simple method for increasing dissolution rates.The objective of this study was to improve solubility,release and comparability of dissolution of a poorly soluble drug using two different types of formulations(solid dispersions and microspheres).Hydrochlorothiazide was used as a model drug.The solid dispersions and microspheres were prepared by solvent evaporation method using ethyl cellulose,hydroxypropyl methylcellulose in different drug-to-carrier ratios(1:1,1:2 w:w).The prepared formulations were evaluated for interaction study by Fourier transform infrared spectroscopy,differential scanning calorimetry,percentage of practical yield,drug loading,surface morphology by scanning electron microscopy,optical microscopy and in-vitro release studies.The results showed no interaction between the drug and polymer,amorphous state of solid dispersions and microspheres,percentage yield of 42.53%to 78.10%,drug content of 99.60%to 99.64%,good spherical appearance in formulation VI and significant increase in the dissolution rate. 展开更多
关键词 HYDROCHLOROTHIAZIDE Ethyl cellulose Hydroxypropyl methylcellulose Second generation solid dispersion MICROSPHERE Solvent evaporation method
下载PDF
Configuration optimization model of multi-energy distributed generation system 被引量:2
3
作者 徐青山 徐敏姣 +1 位作者 李国栋 蒋菱 《Journal of Southeast University(English Edition)》 EI CAS 2017年第2期182-188,共7页
To integrate different renewable energy resources effectively in a microgrid, a configuration optimization model of a multi-energy distributed generation(DG) system and its auxiliary equipment is proposed. The model... To integrate different renewable energy resources effectively in a microgrid, a configuration optimization model of a multi-energy distributed generation(DG) system and its auxiliary equipment is proposed. The model mainly consists of two parts, the determination of initial configuration schemes according to user preference and the selection of the optimal scheme. The comprehensive evaluation index(CEI), which is acquired through the analytic hierarchy process(AHP) weight calculation method, is adopted as the evaluation criterion to rank the initial schemes. The optimal scheme is obtained according to the ranking results. The proposed model takes the diversity of different equipment parameters and investment cost into consideration and can give relatively suitable and economical suggestions for system configuration.Additionally, unlike Homer Pro, the proposed model considers the complementation of different renewable energy resources, and thus the rationality of the multi-energy DG system is improved compared with the single evaluation criterion method which only considers the total cost. 展开更多
关键词 multi-energy complementation distributed generation(dg optimal configuration energy management comprehensive evaluation index(CEI) analytic hierarchy process(AHP)
下载PDF
Islanding Detection Method for Multi-Inverter Distributed Generation 被引量:3
4
作者 Alben CARDENAS Kodjo AGBOSSOU Mamadou Lamine DOUMBIA 《Journal of Electromagnetic Analysis and Applications》 2009年第3期170-180,共11页
Islanding detection is an essential function for safety and reliability in grid-connected distributed generation (DG) systems. Several methods for islanding detection are proposed, but most of them may fail under mult... Islanding detection is an essential function for safety and reliability in grid-connected distributed generation (DG) systems. Several methods for islanding detection are proposed, but most of them may fail under multi-source configurations, or they may produce important power quality degradation which gets worse with increasing DG penetration. This paper presents an active islanding detection algorithm for Voltage Source Inverter (VSI) based multi-source DG systems. The proposed method is based on the Voltage Positive Feedback (VPF) theory to generate a limited active power perturbation. Theoretical analyses were performed and simulations by MATLAB /Simulink /SimPowerSystems were used to evaluate the algorithm’s performance and its advantages concerning the time response and the effects on power quality, which turned out to be negligible. The algorithm performance was tested under critical conditions: load with unity power factor, load with high quality factor, and load matching DER’s powers. 展开更多
关键词 Distributed generation (dg) Interconnected POWER Systems ISLANDING Detection POWER generation Voltage POSITIVE Feedback.
下载PDF
A Comprehensive Review of Protection Schemes for Distributed Generation 被引量:1
5
作者 Umair Shahzad Sohrab Asgarpoor 《Energy and Power Engineering》 2017年第8期430-463,共34页
Due to the increasing demand of energy and the need for nonconventional energy sources, distributed generation (DG) has come into play. The trend of unidirectional power flow has been gradually shifting. With new tech... Due to the increasing demand of energy and the need for nonconventional energy sources, distributed generation (DG) has come into play. The trend of unidirectional power flow has been gradually shifting. With new technology comes new challenges, the introduction of DG into the conventional power system brings various challenges;one of the major challenges is system protection under DG sources. These sources pose a significant challenge due to bidirectional flows from DGs as well as lower fault current contribution from inverter interfaced DGs. This paper reviews existing protection schemes that have been suggested for active distribution networks. Most of these protection strategies apply only to smaller distribution systems implying that they may need to be extended to larger systems with a much higher penetration of distributed generation. In the end, a potential protection scheme has also been recommended as a future work. 展开更多
关键词 Distributed generation (dg) Energy PROTECTION SCHEMES ACTIVE Distribution Networks
下载PDF
Protection of Distributed Generation: Challenges and Solutions 被引量:1
6
作者 Umair Shahzad Salman Kahrobaee Sohrab Asgarpoor 《Energy and Power Engineering》 2017年第10期614-653,共40页
Distributed generation (DG) is the future of energy. This technology allows the bidirectional flow of power within an electrical network. Researchers are faced with many challenges to the accurate implementation of pr... Distributed generation (DG) is the future of energy. This technology allows the bidirectional flow of power within an electrical network. Researchers are faced with many challenges to the accurate implementation of protection schemes for DG-connected distribution network. The schemes designed must satisfy the performance requirements of selectivity, reliability, and sensitivity. Most researchers opine that conventional protection schemes based on over current detection are insufficient to completely and accurately protect a DG-connected distributed power system. There are many challenges?that?need to be tackled before embarking upon the journey to successfully implement these schemes. This paper summarizes the major challenges which one can encounter while designing protection schemes for DG-connected distribution networks. Some possible solutions from the literature are also mentioned. Moreover, a suggested solution for protecting future active distribution networks is provided. It is expected that this paper will act as a benchmark for future researchers in this field to tackle the challenges related to the protection of active distribution networks. 展开更多
关键词 Distributed generation (dg) Energy SELECTIVITY Sensitivity RELIABILITY PROTECTION SCHEMES ACTIVE Distribution Networks
下载PDF
Optimal Placement and Sizing of Distributed Generation Using Metaheuristic Algorithm
7
作者 D.Nageswari N.Kalaiarasi G.Geethamahalakshmi 《Computer Systems Science & Engineering》 SCIE EI 2022年第5期493-509,共17页
Power loss and voltage uncertainty are the major issues prevalently faced in the design of distribution systems.But such issues can be resolved through effective usage of networking reconfiguration that has a combinat... Power loss and voltage uncertainty are the major issues prevalently faced in the design of distribution systems.But such issues can be resolved through effective usage of networking reconfiguration that has a combination of Distributed Generation(DG)units from distribution networks.In this point of view,optimal placement and sizing of DGs are effective ways to boost the performance of power systems.The optimum allocation of DGs resolves various problems namely,power loss,voltage profile improvement,enhanced reliability,system stability,and performance.Several research works have been conducted to address the distribution system problems in terms of power loss,energy loss,voltage profile,and voltage stability depending upon optimal DG distribution.With this motivation,the current study designs a Chaotic Artificial Flora Optimization based on Optimal Placement and Sizing of DGs(CAFO-OPSDG)to enhance the voltage profiles and mitigate the power loss.Besides,the CAFO algorithm is derived from the incorporation of chaos theory concept into conventional artificial flora optimization AFO algorithm with an aim to enhance the global optimization abilities.The fitness function of CAFO-OPSDG algorithm involves voltage regulation,power loss minimization,and penalty cost.To consider the actual power system scenario,the penalty factor acts as an important element not only to minimize the total power loss but to increase the voltage profiles as well.The experimental validation of the CAFO-OPSDG algorithm was conducted against IEEE 33 Bus system and IEEE 69 Bus system.The outcomes were examined under various test scenarios.The results of the experiment established that the presented CAFO-OPSDG model is effective in terms of reducing the power loss and voltage deviation and boost-up the voltage profile for the specified system. 展开更多
关键词 Voltage profile enhancement loss minimization distributed generation optimal dg sizing optimal dg placement metaheuristics
下载PDF
Theoretical Calculation of Ultrashort-Pulse Optical Parametric Generation
8
作者 李旭 朱振和 +1 位作者 顾涛 孙雨南 《Journal of Beijing Institute of Technology》 EI CAS 2005年第4期369-372,共4页
A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is pr... A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is proposed for coherent ultrashort pulses with arbitrary shapes and carrier chirps. The coupled differential equations are numerically solved using a symmetric split step beam-propagation method. The general solutions of these equations are obtained and the optical parametric generation process is theoretically investigated. Results show that the major factors, which remarkably affect the optical parametric conversion efficiency and durations of the pulses in phase-matched structure, are the group velocity mismatch and the intrapulse group velocity dispersion. 展开更多
关键词 optical parametric generation group velocity mismatch intrapulse group-velocity dispersion
下载PDF
Enhancement of Distributed Generation by Using Custom Power Device
9
作者 Kishor V.Bhadane M.S.Ballal R.M.Moharil 《Journal of Electronic Science and Technology》 CAS CSCD 2015年第3期246-254,共9页
Wind energy (WE) has become immensely popular for distributed generation (DG). This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric ... Wind energy (WE) has become immensely popular for distributed generation (DG). This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device (CPD) is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator (DSTATCOM), is utilized for injecting the wind power to the point of common coupling (PCC) and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified. 展开更多
关键词 Custom power device distributed generation (dg distributed static synchronous compensator (DSTATCOM) indirect current control scheme reactive power
下载PDF
Availability, Performance and Reliability Evaluation for PV Distributed Generation
10
作者 Abdulrahman K. Al-Sefri Abdullah M. Al-Shaalan 《World Journal of Engineering and Technology》 2019年第3期429-454,共26页
Nowadays, renewable energy resources play an important role in replacing conventional energy resources such as fossil fuel by integrating solar, wind and geothermal energy. Photovoltaic energy is one?of?the very promi... Nowadays, renewable energy resources play an important role in replacing conventional energy resources such as fossil fuel by integrating solar, wind and geothermal energy. Photovoltaic energy is one?of?the very promising renewable energy resources which grew rapidly in the past few years, it can be used to produce electric energy through photovoltaic process. The primary objective of the research proposed in this paper is to facilitate the increasing penetration levels of PV systems in the electric distribution networks. In this work, the PV module electrical model is presented based on the mathematical equations and was implemented on MATLAB to simulate the non-linear characteristics I-V and P-V curves with variable input parameters which are irradiance and temperature based on Riyadh region. In addition, the reliability evaluation of distribution networks, including distributed generators of solar photovoltaic (PV) with varying output power capacity is presented also. The Monte Carlo simulation algorithm is applied to test the distribution network which is RBTS Bus 2 and the same has been conducted on the original case of distribution network substation 7029 which is located at KSA Riyadh. The two distribution networks have been modified to include the PV’s distributed generators. The distributed generators contribute to supply a part of the load during normal mode and supply the entire load during component failure or failure of grid operation supply. The PV stochastic models have been used to simulate the randomness of these resources. Moreover, the study shows that the implementation and integration of renewable resources as distributed generations have improved the reliability of the distribution networks. 展开更多
关键词 RENEWABLE RESOURCES PHOTOVOLTAIC (PV) Energy Distributed generation (dg) Distribution Networks
下载PDF
Mitigation of Distributed Generation Impact on Protective Devices in a Distribution Network by Superconducting Fault Current Limiter
11
作者 Yu Zhao Yong Li +1 位作者 Tapan Kumar Saha Olav Krause 《Energy and Power Engineering》 2013年第4期258-263,共6页
Protection of radial distribution networks is widely based on coordinated inverse time overcurrent relays (OCRs) ensuring both effectiveness and selectivity. However, the integration of distributed generation (DG) int... Protection of radial distribution networks is widely based on coordinated inverse time overcurrent relays (OCRs) ensuring both effectiveness and selectivity. However, the integration of distributed generation (DG) into an existing distribution network not only inevitably increases fault current levels to levels that may exceed the OCR ratings, but it may also disturb the original overcurrent relay coordination adversely effecting protection selectivity. To analyze the potentially adverse impact of DG on distribution system protective devices with respect to circuit breaker ratings and OCR coordination fault current studies are carried out for common reference test system under the influence of additional DG. The possible advantages of Superconducting Fault Current Limiter (SFCL) as a means to limit the adverse effect of DG on distribution system protection and their effectiveness will be demonstrated. Furthermore, minimum SFCL impedances required to avoid miss-operation of the primary and back-up OCRs are determined. The theoretical analysis will be validated using the IEEE 13-bus distribution test system is used. Both theoretical and simulation results indicate that the proposed application of SFCL is a viable option to effectively mitigate the DG impact on protective devices, thus enhancing the reliability of distribution network interfaced with DG. 展开更多
关键词 OVERCURRENT Relay (OCR) Distribution Protection Coordination Distributed generation (dg) FAULT CURRENT Superconducting FAULT CURRENT LIMITER (SFCL)
下载PDF
Impact of PV Distributed Generation on Loop Distribution Network
12
作者 Mohammad A. Alrumaih Abdullah M. Al-Shaalan 《Journal of Power and Energy Engineering》 2019年第8期27-42,共16页
The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods ... The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods have been used and applied to determine the optimal allocation and sizing of the PV to be installed as DGs (ranging from 250 kW up to 3 MW). The first one is to determine the location according to the maximal power losses reduction over the feeder. The second one is by using the Harmony Search Algorithm which is claimed to be a powerful technique for optimal allocation of PV systems. The results of the two techniques were compared and found to be nearly closed. Furthermore, investigation on the effects on the feeder in terms of voltage levels, power factor readings, and short circuit current levels has been done. All calculations and simulations are conducted by using the MATLAB Simulation Program. Some field calculations and observations have been expended in order to substantiate the research findings and validation. 展开更多
关键词 Distributed generation (dg) FEEDER Photovoltaic System (PV) Power Factor Ring Main Unit (RMU) Short Circuit Current Voltage INSTABILITY
下载PDF
A Practical Approach Based on Equal Area Criteria for Stability Analysis of Weak Networks with Wind Generation Penetration
13
作者 Rene Rossi Mohammad A.S. Masoum 《Journal of Energy and Power Engineering》 2012年第4期629-637,共9页
The performance of DFIG-based wind generation systems that interconnected to solid networks is well understood and prevalent in Europe and North America. However, the application of these renewable generating stations... The performance of DFIG-based wind generation systems that interconnected to solid networks is well understood and prevalent in Europe and North America. However, the application of these renewable generating stations to weak network has been examined in very limited occasions. Weak networks have a range of limitations from system capacities to CFCT restrictions which would need to be well understood prior to wind energy integration. Of particular interest would be how much wind generation could be integrated into a weak network prior to increasing voltage and frequency stability issues brought about by penetration issues. This paper introduces a simple and practical approach based on the equal area criteria to investigate the stability of weak networks. Simulation results that are presented to show the proposed approach is a viable preliminary assessment tool to determine system stability on weak networks with wind power penetration. 展开更多
关键词 Grid system weak system wind farm SWIS (south west interconnection system) CFCT (critical fault clearing time) dg (distributed generation EAC (equal area criteria).
下载PDF
Utilization of DFIG on an Islanded Power Generation and Distribution System
14
作者 Rene Rossi Mohammad Masoum 《Journal of Energy and Power Engineering》 2014年第1期166-175,共10页
The utilization of wind generation equipment, such as DFIGs (double fed induction generators), interconnected to islanded power generation and distribution systems is investigated in order to determine their effects... The utilization of wind generation equipment, such as DFIGs (double fed induction generators), interconnected to islanded power generation and distribution systems is investigated in order to determine their effects on the overall system operating characteristics and stability. The use of a stable power station (with high speed machines) will be critical in achieving fast and reliable transient response to network events, in particular, when large transient loads are expected on a continuous basis, i.e., industrial mining and mineral processing equipment. Simulation results of this paper assist in understanding how small power stations and wind generation equipment respond to large transients in an islanded network. In particular, detailed simulations and analyses will be presented on impacts of distributed wind generation units (1.5 MW DF1G) on the stability of a small weak network. The novelty of this paper is on detailed analyses and simulation of weak networks with interconnects DFIG's including their impacts on system stability under various transient operating conditions. 展开更多
关键词 Grid system weak network dg (distributed generation DFIG (double fed induction generator) DOL (direct on line) VVVF (variable voltage variable frequency) CFCT (critical fault clearing time).
下载PDF
基于缺陷地慢波传输线结构的液晶移相器设计
15
作者 李梓玲 冯燕 +3 位作者 司马博羽 许恒飞 王志诚 吴文 《空军工程大学学报》 CSCD 北大核心 2024年第2期123-127,共5页
为了实现低插损、大相位覆盖范围的加载缺陷地结构(DGS)的微带线液晶移相器,利用HFSS仿真软件对DGS微带线液晶移相器进行建模和仿真,通过改变DGS的形状来改变单个移相单元的色散特性,提升单个单元的移相能力,从而减少移相单元的使用数量... 为了实现低插损、大相位覆盖范围的加载缺陷地结构(DGS)的微带线液晶移相器,利用HFSS仿真软件对DGS微带线液晶移相器进行建模和仿真,通过改变DGS的形状来改变单个移相单元的色散特性,提升单个单元的移相能力,从而减少移相单元的使用数量,降低移相器传输线整体插损。以哑铃型DGS的液晶微带线移相器作为参考标准,比较了5种形状的DGS(哑铃型、减少DGS面积、一阶分形、三角形、交叉型)的移相能力和插损差异。仿真结果表明:下一阶分形和交叉型DGS微带线液晶移相器移相能力较好,最后对不同介电常数的移相器进行仿具观察其S参数和移相能力,进一步验证了这一结果。 展开更多
关键词 缺陷地结构 液晶 移相器 色散 S参数
下载PDF
计算气动声学中的高阶Nodal-DG方法研究 被引量:1
16
作者 陈二云 赵改平 +1 位作者 杨爱玲 卓文涛 《振动与冲击》 EI CSCD 北大核心 2012年第3期168-171,共4页
气动噪声的直接模拟对数值格式的色散、耗散特性提出了严格的要求。基于描述声波的线性双曲方程,运用本征值方法分析了高阶Nodal-DG方法的色散、耗散特性。结果发现,对于任意给定的m阶多项式基函数,数值波解有m+1个值,但仅有一个能够表... 气动噪声的直接模拟对数值格式的色散、耗散特性提出了严格的要求。基于描述声波的线性双曲方程,运用本征值方法分析了高阶Nodal-DG方法的色散、耗散特性。结果发现,对于任意给定的m阶多项式基函数,数值波解有m+1个值,但仅有一个能够表示对应微分方程的物理波传播方式,其余的都是寄生波,且两种波型的传播方向相反。通过与Tam的DRP格式和Lele的六阶紧致格式进行比较,发现在相同的计算精度下,Nodal-DG方法的有效求解波数范围介于DRP格式和六阶紧致格式之间。通过对初始扰动为高斯波形的计算比较发现,在较少的网格数下,Nodal-DG方法的计算结果可以与紧致格式的计算结果相比,但优于DRP格式的计算结果,非常适合于气动声学的数值模拟,为气动声场的直接计算提供了一种新的方法。 展开更多
关键词 计算气动声学 色散耗散特性 Nodal-dg方法
下载PDF
Enhanced wide-angle third-harmonic generation in flat-band-engineered quasi-BIC metagratings
17
作者 Yijia Zang Ruoheng Chai +4 位作者 Wenwei Liu Zhancheng Li Hua Cheng Jianguo Tian Shuqi Chen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2024年第4期81-87,共7页
Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial struc... Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial structures.However,the nonlinear conversion efficiency is generally limited by the angular dispersion of optical resonances especially in nonparaxial photonics.Here,we propose a metagrating realizing a quasi-bound-state in the continuum in a flat band to dramatically improve the third harmonic generation(THG)efficiency.A superior operating angular range is achieved based on the interlayer and intralayer couplings,which are introduced by breaking the mirror symmetry of the metagrating.We demonstrate the relation of angular dispersion between the nonlinear and linear responses at different incident angles.We also elucidate the mechanism of these offaxis flat-band-based nonlinear conversions through different mode decomposition.Our scheme provides a robust and analytical way for nonparaxial nonlinear generation and paves the way for further applications such as wide-angle nonlinear information transmission and enhanced nonlinear generation under tight focusing. 展开更多
关键词 nonlinear metasurfaces quasi-bound-state in the continuum angular dispersion third harmonic generation efficiency
原文传递
Inverse-time Backup Protection Based on Unified Characteristic Equation for Distribution Networks with High Proportion of Distributed Generations
18
作者 Nana Chang Guobing Song +2 位作者 Zhongxue Chang Yuping Zheng Xingang Yang 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2024年第1期202-212,共11页
The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power grid.Thus,there is a ... The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power grid.Thus,there is a practical need to study a backup protection technology that does not require step-by-step setting and can be adaptively coordinated.This paper proposes an action sequence adaptive to fault positions that uses only positive sequence fault component(PSFC)voltage.Considering the influence of DGs,the unified time dial setting can be obtained by selecting specific points.The protection performance is improved by using the adjacent upstream and downstream protections to meet the coordination time interval in the case of metallic faults at the near-and far-ends of the line.Finally,the expression and implementation scheme for inverse-time backup protection(ITBP)based on the unified characteristic equation is given.Simulation results show that this scheme can adapt to DG penetration scenarios and can realize the adaptive coordination of multi-level relays. 展开更多
关键词 Inverse-time backup protection(ITBP) distributed generation(dg) positive sequence fault component(PSFC)voltage unified characteristic equation adaptive coordination
原文传递
Cumulative Air Quality Impacts from Twenty-Two Major Power Plants
19
作者 Md M.Karim Navin Bindra Arub Masud 《Journal of Environmental Science and Engineering(A)》 CAS 2024年第1期1-14,共14页
Cumulative assessment is a tool for the project developer to try and take into consideration not only their contribution to cumulative impacts but also other projects and external factors that may place their developm... Cumulative assessment is a tool for the project developer to try and take into consideration not only their contribution to cumulative impacts but also other projects and external factors that may place their developments at risk.This study assessed the cumulative impacts of air emissions from 22 major power plants in southeast Bangladesh planned to generate 21,550 MW of electricity.It also includes anticipated growth in small to medium size industries,brickfields,highway traffic,inland water transport,transhippers,jetty,and vessel transports used for transporting fuel resources for these power plants.A 50 km by 50 km airshed is considered for air quality modeling.Cumulative analysis indicates that predicted MGLCs(Maximum Ground Level Concentrations)of NO2 and CO are complying with both Bangladesh NAAQS(National Ambient Air Quality Standards)and WBG(World Bank Group)Guidelines.The daily average MGLC of PM_(2.5)(62.45µg/m^(3))from all sources complies with NAAQS,however,exceeds the WBG Guidelines.Annual PM_(2.5) concentration(15.45µg/m^(3))exceeds NAAQS and WBG Guidelines.The PM10 concentration complies with the NAAQS for both 24-hour and annual averaging times.Annual average concentration(23.12µg/m^(3))exceeds WBG Guidelines.Daily average SO2 concentration(102.49µg/m^(3))complies with the NAAQS however,it exceeds the WBG guideline values.High concentrations of PM_(2.5) and SO2 are due to the contribution of transboundary emissions and secondary pollutants in the atmosphere.This dispersion modeling outcome can be used by the policymakers for the pollution reduction strategy. 展开更多
关键词 CIA(Cumulative Impact Assessment) dispersion modeling power generation Bangladesh.
下载PDF
Power loss reduction of distribution systems using BFO based optimal reconfiguration along with DG and shunt capacitor placement simultaneously in fuzzy framework 被引量:1
20
作者 M.Mohammadi A.Mohammadi Rozbahani S.Bahmanyar 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第1期90-103,共14页
In distribution systems,network reconfiguration and capacitor placement are commonly used to diminish power losses and keep voltage profiles within acceptable limits.Moreover,the problem of DG allocation and sizing is... In distribution systems,network reconfiguration and capacitor placement are commonly used to diminish power losses and keep voltage profiles within acceptable limits.Moreover,the problem of DG allocation and sizing is great important.In this work,a combination of a fuzzy multi-objective approach and bacterial foraging optimization(BFO) as a meta-heuristic algorithm is used to solve the simultaneous reconfiguration and optimal sizing of DGs and shunt capacitors in a distribution system.Each objective is transferred into fuzzy domain using its membership function.Then,the overall fuzzy satisfaction function is formed and considered a fitness function inasmuch as the value of this function has to be maximized to gain the optimal solution.The numerical results show that the presented algorithm improves the performance much more than other meta-heuristic algorithms.Simulation results found that simultaneous reconfiguration with DG and shunt capacitors allocation(case 5) has 77.41%,42.15%,and 56.14%improvements in power loss reduction,load balancing,and voltage profile indices,respectively in 33-bus test system.This result found 87.27%,35.82%,and 54.34%improvements of mentioned indices respectively for 69-bus system. 展开更多
关键词 network reconfiguration distributed generation (dg capacitor banks fuzzy framework bacterial foragingoptimization
下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部