Results 251 to 260 of about 67,464 (300)

Virtual impedance design of virtual synchronous generation in microgrid

2014 International Power Electronics and Application Conference and Exposition, 2014
The adoption of virtual synchronous generation (VSG) control can maintain the stability of voltage and frequency in power electronic interfaced mircogrid. In this paper virtual impedance is added to the VSG control strategy in order to improve the system control performance in resistive-inductive line impedance, the influence of virtual impedance on ...
Chao Hu, Fang Liu, Haizhen Xu, Rongliang Shi, Lei Tao   +4 more
openaire   +1 more source

Virtual Impedance Adaptive Study of Parallel Virtual Synchronous Generators

2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019
As the increasing of the capacity of the micro grid, it is difficult for a single VSG-controlled inverter to meet the requirements of micro grid use. VSG operating in parallel has become the main solution, and the problem of equalization in the division has naturally become the focus of research.
Chunxue Wen, Yaozhi Huang, Qi Xiong
openaire   +1 more source

Object shape virtualization in impedance tomography

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2009
PurposeThe purpose of this paper is to introduce a method for increasing imaging quality in impedance tomography. The paper presents an optical method of shape virtualization, processing algorithm draft and results of virtualization for sample objects.Design/methodology/approachIn impedance tomography the image reconstruction algorithms must yield ...
Tomasz Grzywacz, Jan Sikora, Stefan Wójtowicz   +2 more
openaire   +1 more source

Virtual Impedance Analyzer Design and Implementation

Second International Conference on Innovative Computing, Informatio and Control (ICICIC 2007), 2007
In this research, the structure and design of virtual impedance analyzers are studied. The construction process is also described and introduced. This programmable virtual impedance analyzer is achieved by software part, Labview, hardware part, DAQ card and some external circuits.
Kai-chao Yao, Chin-wen Liao, Li-ling Chao, Fu-yu Lin   +3 more
openaire   +1 more source

Virtual Impedance Design Considerations for Virtual Synchronous Machines in Weak Grids

IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020
Most renewable energy sources (RESs) are interfaced to electricity grids via voltage-source converters (VSCs). To facilitate the integration, the controllers based on the emulation of synchronous generators have been increasingly used. This control technique is commonly referred to as Virtual Synchronous Machine (VSM) and recent studies have shown that
Alberto Rodriguez-Cabero, Javier Roldan-Perez, Milan Prodanovic   +2 more
openaire   +1 more source

Damping Effect of Virtual Synchronous Machines Provided by a Dynamical Virtual Impedance

IEEE Transactions on Energy Conversion, 2021
Virtual synchronous machines (VSMs) emulate the swing equation for grid synchronization and inertia provision. Usually, a large damping coefficient is necessary in VSMs to provide equivalent damper winding effect, which is, however, not aligned with the fact that the physical swing equation of synchronous generators (SGs) contains only a small ...
Linbin Huang, Huanhai Xin, Hui Yuan, Guanzhong Wang, Ping Ju   +4 more
openaire   +1 more source

A Novel Virtual Impedance Method for Interfacing Renewable to Grid with High Impedance

2023 IEEE PES Innovative Smart Grid Technologies - Asia (ISGT Asia), 2023
Currently, grid-following inverter (GFL) has become a vital component in the integration of renewable energy sources into power grids. A Modified Virtual Impedance - Phase Locked Loop (MVI-PLL) method is proposed to address instability problems that occur when using a PLL under high grid impedance conditions in GFL.
Nguyen, Phuoc Sang, Nourbakhsh, Ghavameddin, Ledwich, Gerard   +2 more
openaire   +2 more sources

Frequency-Coupled Impedance Modeling of Virtual Synchronous Generators

IEEE Transactions on Power Systems, 2021
The impedance of the virtual synchronous generator (VSG) is an effective method to analyze the dynamic interactions between the VSG and the grid. For the existence of power controllers and asymmetric inner-loop controllers in the d- and q-axis, there are couplings in the output sequence impedance of VSG.
Kai Shi, Yu Wang, Yuxin Sun, Peifeng Xu, Feng Gao   +4 more
openaire   +1 more source

Modified Adaptive Virtual Impedance Method to Compensate Mismatched Line Impedances in Microgrids

2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
Under mismatched line impedance conditions, reactive power sharing performance of droop control tends to be barely satisfactory for the absence of sharing accuracy. Therefore, to realize accurate reactive power sharing of parallel-connected inverters in microgrids, a modified adaptive virtual impedance method is proposed in this paper.
Ronghui AN, Zeng LIU, Jinjun LIU
openaire   +1 more source

Virtual Biopsies in Barrett's Esophagus Using an Impedance Probe

Annals of the New York Academy of Sciences, 1999
Abstract: Preliminary results of electrical impedance measurements in squamous and columnar epithelia in rat and human tissues are presented. The aim of this work is to show the possibility of differentiating these two types of epithelia in terms of their electrical characteristics. For the measurements, we employed a 1.95m‐long, 3.2‐mm‐diameter, four‐
C A, González-Correa, B H, Brown, R H, Smallwood, N, Kalia, C J, Stoddard, T J, Stephenson, S J, Haggie, D N, Slater, K D, Bardhan   +8 more
openaire   +2 more sources