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- 2018
- rural electrification
- optimised renewable energy utilisation
- power sharing
- micro grid
- community development
- grid interconnection
- IoT based data acquisition system
- Grid tie solar PV system
- IoT
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- Electrical Engineering and Automation
- Amrita School of Engineering
- Zeal College of Engineering and Research
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Microwave photonics‐based all optical wavelength conversion of Nyquist‐DP‐16QAM for flex‐grid optical networks with 112 Gbps
摘要： We propose and demonstrate an all optical wavelength conversion of Nyquist differential phase 16 quadrature amplitude modulation based on microwave photonics signal processing for flex-grid optical networks. By analyzing the mechanism of the microwave photonics and the components, multi-adjusting the parameters of wavelength tunable laser with smooth and adjustable optical intensity can be obtained. Then, the multi-channel photonic signals with the minimal guard space of 5 GHz can be obtained, which provide more than 20 flex-grids for optical transmission with transparent rate and format. The optical power of converted wavelengths, optical signal-to-noise ratio, error vector magnitude, and bit error rate (BER) are studied under the condition of different flex-grids, the frequencies of which are from 15 GHz to 36 GHz. The channel frequency spacing and amplitude of the converted wavelength can be dynamically adjusted via parameter configuration. Flex-grid spacing strategies and channel selecting strategies are given. The BER performance of all converted channels can fall below the forward error correction threshold of 3.8 × 10?3 by optimizing the optical power of the receiver end. The results show the tradeoff between the BER and the detected optical power of the receiver end. These research findings could provide solutions for spectrum allocation and routing selection when wavelength conversion is needed in optical links.
关键词： coherent communication,microwave photonics,wavelength conversion,flex-grid optical networks
更新于2025-09-23 15:22:29
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Bevacizumab versus bevacizumab and macular grid photocoagulation for macular edema in eyes with non-ischemic branch retinal vein occlusion: results from a prospective randomized study
摘要： Background The objective of the study was the investigation of the effects of intravitreal bevacizumab (BEV) with or without additional macular grid laser photocoagulation (GRID) for macular edema (ME) secondary to branch retinal vein occlusion (BRVO). Methods Prospective, randomized, monocentric study. Thirty-two patients were included. Initially, all eyes in both groups received three monthly injections of BEV, followed by additional injections if re-treatment criteria were met. In the BEV + GRID group, photocoagulation was performed 2 weeks after the first BEV injection and laser re-treatment was allowed. The follow-up was 38 weeks. Main outcome measures were best-corrected visual acuity (BCVA) and central retinal thickness (CRT). Changes of foveal avascular zone (FAZ) and of retinal ischemia, as well as the number of injections were also evaluated. Results Sixteen eyes were randomized into each group. At baseline, BCVA was similar in both groups (BEV + GRID: 20/71; BEV: 20/60; P = 0.51). At 38 weeks, BCVA significantly improved in the two groups (BEV + GRID gain of 9 ± 11.2 letters and 16.25 ± 10.08 letters in the BEV) with no difference between them (P < 0.06). With regard to anatomical findings, initial CRT in BEV + GRID was 496.2 μm ± 138.4 μm and 538.9 μm ± 156.9 μm in BEV (P < 0.1697). At 38 weeks, CRT decreased in both groups significantly, 98.2 μm in the BEV + GRID (P = 0.02) and 141.7 μm in the BEV group (P = 0.01), with no significant difference between groups (P < 0.17). The area of FAZ a significantly increased in both groups (41% (P = 0.04) in BEV + GRID; 35% (P = 0.03) in BEV) during the study and the grade of peripheral ischemia remained unchanged. The mean number of injections was 3.8 (range 3–6) with no significant difference between groups. Conclusions Our data demonstrate a beneficial effect of bevacizumab in ME in eyes with BRVO. A loading phase of three injections led to a significant improvement in vision in both groups, which persisted at week 38. Additional grid laser photocoagulation exhibited no beneficial functional or anatomical effect during the study, nor did it reduce the number of injections. The FAZ area increased significantly in both groups, but overall retinal ischemia did not. Further studies investigating more numerous eyes and longer follow-up are needed to confirm these data.
关键词： Anti-VEGF,Grid laser photocoagulation,Macular edema,Branch retinal vein occlusion,Bevacizumab
更新于2025-09-23 15:22:29
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - A DPWM based Control Strategy to Integrate Photovoltaic System and Battery Storage using Grid Connected Three-level T-Type Inverter
摘要： In this paper, integration of photovoltaic (PV) system and battery storage is considered using Three-level T-Type inverter. To attain the highest efficiency, PV panels are considered to follow MPPT algorithm while batteries are operated based on their state of charge (SOC) condition. To provide distortion-free output current, it is essential considering unbalanced condition produced due to inconsistency of MPPT and SOC. Moreover, proper tradeoff between inverter and grid is realized so that inverter is automatically adapted with demand-power of grid. All the targets are carried out by proper control of Discontinuous PWM. The proposed method is evaluated by simulation study.
关键词： DPWM,Battery-SOC,MPPT algorithm,Grid connected three-level T-type inverter
更新于2025-09-23 15:22:29
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An H5 Transformerless Inverter for Grid Connected PV Systems with Improved Utilization Factor and a Simple Maximum Power Point Algorithm
摘要： Due to their small size, minimum cost, and great efficiency, photovoltaic (PV) grid-connected transformerless inverters have been developed and become famous around the world in distributed PV generators systems. One of the most efficient topologies of the transformerless inverter family is H5 topology. This inverter extracts a discontinuous current from the PV panel, which conflicts with the operation at maximum power point tracking (MPPT) conditions while the utilization factor of the PV degrades. This paper proposes improved H5 topology featuring a boost converter inserted in the middle between the PV panels and the H5 inverter. The design of the boost converter is planned to operate at continuous conduction mode to guarantee MPPT conditions of the PV. A new and simple off line MPPT algorithm is introduced and performance factors like efficiency and utilization factors of the proposed and convention H5 topology are compared. The simulation results indicate that the proposed system provides a preferable utilization factor and a simpler MPPT algorithm.
关键词： boost converter,PV panel,utilization factor,H5 inverter,utility grid,MPPT
更新于2025-09-23 15:22:29
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22.3: Low cost fabrication of high contrast ratio and high transmission wire grid polarizer by nanoimprint lithography
摘要： This paper proposes a novel approach for low cost fabrication of large area wire grid polarizer (WGP). WGPs regarded as one potential alternative to traditional rear polarizer and DBEF possess the advantages of large contrast ratio (CR), high transmission. To date WGPs can be fabricated through electron beam direct write, which is slow and expensive, therefore not suitable for large area application. With the development of nano-fabrication methods, for instance, nanoimprint lithography (NIL), large area WGP can be made at low cost and fast speed. Furthermore, flexible polarizer can also be made through roll-to-roll (R2R) NIL. In this paper, a WGP with high TM transmission of around 85% and low TE transmission down to 0.2% through the visible light spectra will be realized through nanofabrication. The contrast ratio of the WGP can reach >450 with peak value >3000. For the fabrication process, atom layer deposition (ALD) will be utilized to prepare imprint mask which can achieve highly precise control of expected structure. In this paper, characterization of the designed WGP will also be narrated in the back part, including transmission, CR and the SEM schematic diagram. We believe that low cost fabrication method shows the potential to be adopted for industrial fabrication of polarizer in the future.
关键词： atom layer deposition (ALD),large area fabrication,low cost fabrication,wire grid polarizer (WGP),high contrast ratio,nanoimprint lithography (NIL),high TM transmission
更新于2025-09-23 15:22:29
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Controller-Hardware-in-the-Loop Testbed for Fast-Switching SiC-Based 50-kW PV Inverter
摘要： The recent advent of wide bandgap power semiconductor devices will lay the path for future power converters. These devices provide the advantage of high switching speed and lower losses. The high cost and high switching speeds of these devices provide a challenge in the development and validation of the fast-switching inverter controls with accuracy comparable to that of a hardware setup. In this paper, a field programmable gate array (FPGA) real-time simulator-based controller-hardware-in-the-loop (CHIL) testbed is used to verify the low-level and advanced inverter controls for fast-switching wide bandgap-based photovoltaic string inverter. The paper also includes development of the CHIL testbed, which is run at a time step of 500 ns in order to implement 20-kHz switching frequency. The developed CHIL testbed is validated through experimental results from a three-phase, 50-kW, 480-VLLrms SiC device-based inverter.
关键词： controller hardware-in-the-loop,high switching frequency,SiC devices,power electronics converters,advanced grid-support functions
更新于2025-09-23 15:22:29
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Different Influence of Grid Impedance on Low- and High- frequency Stability of PV Generators
摘要： Recently, the stability issues when renewable energy sources are connected to weak grid have obtained great attention. The popular view thinks that the grid impedance is adverse to the system stability. However, in this paper, it is first found that for the photovoltaic (PV) generator, the grid impedance has different influence on the system stability depending on the frequency range when the complete model of the PV generator is taken into consideration. That is, the increase of grid impedance can suppress the low-frequency (<50 Hz) oscillation, while the increase of grid impedance degrades the high-frequency (>300 Hz) stability. Concretely, for the low-frequency range mainly dominated by the power loop and voltage loop of the PV generator, the describing function method is adopted to overcome discontinuity and nonlinearity of the power loop. Then, the low-frequency dynamics like power oscillation can be analyzed accurately. For the high-frequency range mainly dominated by the phase-locked loop and current loop of the PV generator, the impedance analysis method is adopted to reveal the high-frequency instability mechanism. Through these analyses, the different influence of grid impedance on the low- and high- frequency stability of PV generators can be clearly distinguished. All the conclusions are verified through the real-time hardware-in-loop (HIL) tests.
关键词： describing function,impedance analysis,PV generators,weak grid,stability analysis
更新于2025-09-23 15:22:29
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[IEEE 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Singapore, Singapore (2018.11.18-2018.11.21)] 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Camera Based Decision Making at Roundabouts for Autonomous Vehicles
摘要： Being able to join roundabouts correctly is crucial for an autonomous vehicle to maintain not only its own safety but also a normal traffic order for others. In order to know the right time and speed for entering roundabouts, the location, speed and direction of the approaching vehicles need to be taken into consideration. This study investigated the feasibility of leveraging computer vision and machine learning to help autonomous vehicles decide to wait or to enter when reaching roundabouts. A grid-based image processing approach with a single camera at normal roundabouts (GBIPA-SC-NR) is proposed in this paper to characterize traffic situations that can be used for machine learning algorithms to learn the roundabout joining criteria. Video road clips recorded when human drivers reach and then join various roundabouts at different locations were utilised for this learning process, with a selection of four supervised classification algorithms (i.e. the Support Vector Machines, Random Forests, K-Nearest Neighbours, and Decision Tree). The trained classifiers using the proposed approach were evaluated on 507 test videos captured at roundabouts, where the SVM showed the best performance with a 90.28% classification accuracy. This result suggests that the proposed grid-based image processing method can be applied to effectively help autonomous vehicles made the right decision when reaching a roundabout.
关键词： Autonomous Vehicle,Grid-based Image Processing,Machine Learning,Roundabout
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Three-Phase AC-Stacked PV Inverter Architecture and Output Balancing Control Strategy with Battery under Asymmetrical Irradiance Conditions
摘要： This paper presents three-phase AC-stacked photovoltaic (PV) inverter architecture integrated with battery and its output balancing control strategy under asymmetrical irradiance conditions. The main objective of this research is to verify the feasibility of decentralized control scheme in the three-phase AC-stacked PV inverter system and mitigate unbalanced output power caused by asymmetrical irradiance conditions. To keep the benefits of the decentralized control, the proposed output balancing control strategy uses local measurement information captured by individual energy storage inverter members. The proposed system is demonstrated and verified through a control-hardware-in-the-loop test.
关键词： decentralized control,asymmetrical irradiance changes,three-phase grid-tied inverter,output balancing control,ac-stacked PV inverter,PR-controller based harmonics filter
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Power & Energy Society General Meeting (PESGM) - Portland, OR, USA (2018.8.5-2018.8.10)] 2018 IEEE Power & Energy Society General Meeting (PESGM) - A Study on Control Strategy of PV inverter for Harmonic Mitigation in A Microgrid
摘要： This paper presents a study of the control strategies of three-phase grid-connected photovoltaic inverter to mitigate its harmonic current output and improve the power quality of the grid. The operation principle and topology of the PV inverter is analyzed by establishing the state-space mathematical model based on the adaptation of proportional resonant (PR) and quasi-proportional resonant (QPR) controllers. According to the characteristics of the PR and QPR controllers, the theories for mitigating harmonic currents are reviewed. A three-phase ac microgrid with grid-connected inverter systems is then built on Matlab/Simulink and the performances of the inverter controllers for harmonic mitigations are verified by comparing the simulation results.
关键词： quasi-PR controller,Three-phase grid-connected PV system,harmonic compensation,inverter
更新于2025-09-23 15:22:29