scholarly journals Grid Synchronization and Islanding Detection Methods for Single-Stage Photovoltaic Systems

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3382 ◽  
Author(s):  
Rosa Anna Mastromauro
Keyword(s):  
Control Function ◽  
Single Stage ◽  
Detection Methods ◽  
Photovoltaic Systems ◽  
Islanding Detection ◽  
Safe Operation ◽  
Synchronization System ◽  
Grid Synchronization ◽  
High Power Factor

Synchronization and islanding detection represent some of the main issues for grid-connected photovoltaic systems (PVSs). The synchronization technique allows to achieve PVS high power factor operation and it provides grid voltage monitoring. The islanding detection control function ensures safe operation of the PVS. Focusing on low-power single-stage PVSs, in this study the most adopted and the highest performance synchronization and islanding detection methods are discussed. The role of the synchronization system is fundamental to detect the grid conditions, for the islanding detection purpose, and to manage the reconnection to the grid after a PVS trip. Hence a combined review is advantageous.

scholarly journals A Novel Single-Switch Single-Stage LED Driver with Power Factor Correction and Current Balancing Capability

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1340
Author(s):  
Yih-Her Yan ◽  
Hung-Liang Cheng ◽  
Chun-An Cheng ◽  
Yong-Nong Chang ◽  
Zong-Xun Wu
Keyword(s):  
Power Factor ◽  
High Power ◽  
Pulse Width Modulation ◽  
Power Factor Correction ◽  
Harmonic Distortion ◽  
Boost Converter ◽  
Single Stage ◽  
Led Driver ◽  
Flyback Converter ◽  
High Power Factor

A novel single-switch single-stage high power factor LED driver is proposed by integrating a flyback converter, a buck–boost converter and a current balance circuit. Only an active switch and a corresponding control circuit are used. The LED power can be adjusted by the control scheme of pulse–width modulation (PWM). The flyback converter performs the function of power factor correction (PFC), which is operated at discontinuous-current mode (DCM) to achieve unity power factor and low total current harmonic distortion (THDi). The buck–boost converter regulates the dc-link voltage to obtain smooth dc voltage for the LED. The current–balance circuit applies the principle of ampere-second balance of capacitors to obtain equal current in each LED string. The steady-state analyses for different operation modes is provided, and the mathematical equations for designing component parameters are conducted. Finally, a 90-W prototype circuit with three LED strings was built and tested. Experimental results show that the current in each LED string is indeed consistent. High power factor and low THDi can be achieved. LED power is regulated from 100% to 25% rated power. Satisfactory performance has proved the feasibility of this circuit.

scholarly journals Viruses and Type 1 Diabetes: From Enteroviruses to the Virome

2021 ◽  
Vol 9 (7) ◽  
pp. 1519
Author(s):  
Sonia R. Isaacs ◽  
Dylan B. Foskett ◽  
Anna J. Maxwell ◽  
Emily J. Ward ◽  
Clare L. Faulkner ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Viral Infections ◽  
Antiviral Drug ◽  
Virus Detection ◽  
Detection Methods ◽  
Islet Autoimmunity ◽  
Comprehensive Overview ◽  
Drug Candidates

For over a century, viruses have left a long trail of evidence implicating them as frequent suspects in the development of type 1 diabetes. Through vigorous interrogation of viral infections in individuals with islet autoimmunity and type 1 diabetes using serological and molecular virus detection methods, as well as mechanistic studies of virus-infected human pancreatic β-cells, the prime suspects have been narrowed down to predominantly human enteroviruses. Here, we provide a comprehensive overview of evidence supporting the hypothesised role of enteroviruses in the development of islet autoimmunity and type 1 diabetes. We also discuss concerns over the historical focus and investigation bias toward enteroviruses and summarise current unbiased efforts aimed at characterising the complete population of viruses (the “virome”) contributing early in life to the development of islet autoimmunity and type 1 diabetes. Finally, we review the range of vaccine and antiviral drug candidates currently being evaluated in clinical trials for the prevention and potential treatment of type 1 diabetes.

scholarly journals Over/Undervoltage and Undervoltage Shift of Hybrid Islanding Detection Method of Distributed Generation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Manop Yingram ◽  
Suttichai Premrudeepreechacharn
Keyword(s):  
Control System ◽  
Distributed Generation ◽  
Hybrid Method ◽  
Detection Method ◽  
System Simulation ◽  
Detection Methods ◽  
Islanding Detection ◽  
Active Method ◽  
Passive Method ◽  
Simulation Results

The mainly used local islanding detection methods may be classified as active and passive methods. Passive methods do not perturb the system but they have larger nondetection zones, whereas active methods have smaller nondetection zones but they perturb the system. In this paper, a new hybrid method is proposed to solve this problem. An over/undervoltage (passive method) has been used to initiate an undervoltage shift (active method), which changes the undervoltage shift of inverter, when the passive method cannot have a clear discrimination between islanding and other events in the system. Simulation results on MATLAB/SIMULINK show that over/undervoltage and undervoltage shifts of hybrid islanding detection method are very effective because they can determine anti-islanding condition very fast.ΔP/P>38.41% could determine anti-islanding condition within 0.04 s;ΔP/P<-24.39% could determine anti-islanding condition within 0.04 s;-24.39%≤ΔP/P≤ 38.41% could determine anti-islanding condition within 0.08 s. This method perturbed the system, only in the case of-24.39% ≤ΔP/P ≤38.41% at which the control system of inverter injected a signal of undervoltage shift as necessary to check if the occurrence condition was an islanding condition or not.

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