scholarly journals A Novel Protection Scheme against Fault Resistance for AC Microgrid

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Xinrui Liu ◽  
Zhiyuan Xie ◽  
Qiuye Sun ◽  
Zhiliang Wang
Keyword(s):  
High Reliability ◽  
High Sensitivity ◽  
Active Power ◽  
Backup Protection ◽  
Protection Scheme ◽  
Fault Resistance ◽  
Different Types ◽  
Islanded Mode ◽  
Resistance Value ◽  
Ac Microgrid

The faults characteristics of the lines in AC microgrid are weakened due to the fault resistance, which may refuse protection action. To solve the problems caused by different types of the faults through fault resistance (FTFR, the faults where the fault point resistance is greater than zero) in AC microgrid, a novel FTFR protection scheme based on the active power of 0-frame component or d-frame component consumed by fault resistance is proposed in this paper as the backup protection of FTFR. This proposed protection scheme utilizes the active power of 0-frame component or d-frame component consumed by fault resistance to identify internal FTFR and external faults. It performs well in grid-connected mode and islanded mode by adopting self-adaptive threshold and is not affected by the factors such as the fault position and the fault resistance value. The theoretical analysis and various simulations show that this protection scheme can identify and isolate different types of internal FTFR in AC microgrid with high reliability and high sensitivity.

scholarly journals Differential Algorithm Based Intelligent Protection Scheme for Microgrid

2019 ◽  
Vol 8 (9S3) ◽  
pp. 128-133
Keyword(s):  
Discrete Wavelet ◽  
Time Duration ◽  
New Approach ◽  
Protection Scheme ◽  
Intelligent Technique ◽  
Course Of Action ◽  
Different Types ◽  
Islanded Mode ◽  
Differential Algorithm ◽  
Types Of Faults

Proposed scheme presents intelligent technique in protection of microgrid. This paper gives new approach in feature extraction of faulted current signal using Discrete Wavelet Transform. Furthermore different parameters like TMS(Time Measurment setting),PSM (Plug setting Multiple ) and CTD (coordination time Duration) are computed from featured faulty current. This course of action used to build genetic differential algorithm for deciding best suitable pair of relay with concept of “survival of fittest”. IEEE 9 bus system is considered for studding different types of faults for utilityconnected and islanded mode. Initially primary pair of relay is activated and secondary protection operates on failure of primary. This study gives effective solution for fast operation of pair of relay in optimized time.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

scholarly journals A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1915
Author(s):  
Shenawar Ali Khan ◽  
Muhammad Saqib ◽  
Muhammad Muqeet Rehman ◽  
Hafiz Mohammad Mutee Ur Rehman ◽  
Sheik Abdur Rahman ◽  
...  
Keyword(s):  
Active Layer ◽  
Humidity Sensor ◽  
High Reliability ◽  
Full Range ◽  
High Sensitivity ◽  
Fast Response ◽  
Considerable Change ◽  
Relative Humidity Range ◽  
Response And Recovery ◽  
Proportional Relationship

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8–98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

Sign in / Sign up

Export Citation Format

Share Document