Estimation of Impedance Ratio Parameters for Consistent Modeling of Tap-Changing Transformers

2021 ◽  
pp. 1-1
Author(s):  
Md Rejwanur Rashid Mojumdar ◽  
Jose M. Cano ◽  
Gonzalo Alonso Orcajo
Keyword(s):  
Impedance Ratio

Detection of bark lesions caused by Phytophthoracinnamomi in Eucalyptusmarginata with the plant impedance ratio meter and the Shigometer

1987 ◽  
Vol 17 (10) ◽  
pp. 1228-1233 ◽  
Author(s):  
Joanna T. Tippett ◽  
Joanne L. Barclay
Keyword(s):  
Water Content ◽  
Electrical Resistance ◽  
Water Status ◽  
Healthy Tissue ◽  
Plant Tissues ◽  
Tissue Water Content ◽  
Tissue Water ◽  
Impedance Ratio ◽  
New Instrument ◽  
Electrical Admittance

A new instrument, the plant impedance ratio meter (PIRM), has been used to determine the extent of lesions caused by Phytophthoracinnamomi Rands in Eucalyptusmarginata Sm. The performance of the PIRM, which measures electrical admittance (the inverse of impedance) of plant tissues at two frequencies (from which an impedance ratio is calculated), was evaluated and compared with that of the Shigometer. The electrical admittance measured at 1 and 10 kHz (PIRM) and the electrical resistance (Shigometer) of healthy tissue varied with both the depth of tissue probed and the water status of stems. However, the impedance ratios (calculated from the admittance values) remained relatively constant for healthy tissue and changes were independent of depth of probing. Hence, changes in ratios indicated a change in tissue condition or necrosis rather than changes in either tissue water content or depth of probing. The impedance ratios recorded for healthy bark tissues were consistently higher than those for the P. cinnamomi lesions in E. marginata. Trends in electrical resistance measured across the boundaries of the lesions with the Shigometer were variable depending on lesion age. The PIRM was used successfully to detect P. cinnamomi lesions in E. marinate and lesion fronts were predicted to an accuracy of ± 7.2 mm (n = 150), lesions being up to 1.0 m long at the time stems were harvested.

scholarly journals Coupling Influence on the dq Impedance Stability Analysis for the Three-Phase Grid-Connected Inverter

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3676
Author(s):  
Chuanyue Li ◽  
Taoufik Qoria ◽  
Frederic Colas ◽  
Jun Liang ◽  
Wenlong Ming ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Nyquist Plot ◽  
Current Control ◽  
Impedance Ratio ◽  
Three Phase ◽  
Grid Impedance ◽  
Nyquist Criterion ◽  
Grid Connected Inverter ◽  
The Stability ◽  
The Right

The dq impedance stability analysis for a grid-connected current-control inverter is based on the impedance ratio matrix. However, the coupled matrix brings difficulties in deriving its eigenvalues for the analysis based on the general Nyquist criterion. If the couplings are ignored for simplification, unacceptable errors will be present in the analysis. In this paper, the influence of the couplings on the dq impedance stability analysis is studied. To take the couplings into account simply, the determinant-based impedance stability analysis is used. The mechanism between the determinant of the impedance-ratio matrix and the inverter stability is unveiled. Compared to the eigenvalues-based analysis, only one determinant rather than two eigenvalue s-function is required for the stability analysis. One Nyquist plot or pole map can be applied to the determinant to check the right-half-plane poles. The accuracy of the determinant-based stability analysis is also checked by comparing with the state-space stability analysis method. For the stability analysis, the coupling influence on the current control, the phase-locked loop, and the grid impedance are studied. The errors can be 10% in the stability analysis if the couplings are ignored.

scholarly journals Impedance-Based Interactions in Grid-Tied Three-Phase Inverters in Renewable Energy Applications

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 464 ◽  
Author(s):  
Teuvo Suntio ◽  
Tuomas Messo ◽  
Matias Berg ◽  
Henrik Alenius ◽  
Tommi Reinikka ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Experimental Measurements ◽  
Stability Assessment ◽  
Transient Performance ◽  
Energy Applications ◽  
Impedance Ratio ◽  
Three Phase ◽  
The Cross ◽  
And Performance ◽  
The Stability

Impedance-ratio-based interaction analyses in terms of stability and performance of DC-DC converters is well established. Similar methods are applied to grid-connected three-phase converters as well, but the multivariable nature of the converters and the grid makes these analyses very complex. This paper surveys the state of the interaction analyses in the grid-connected three-phase converters, which are used in renewable-energy applications. The surveys show clearly that the impedance-ratio-based stability assessment are usually performed neglecting the cross-couplings between the impedance elements for reducing the complexity of the analyses. In addition, the interactions, which affect the transient performance, are not treated usually at all due to the missing of the corresponding analytic formulations. This paper introduces the missing formulations as well as explicitly showing that the cross-couplings of the impedance elements have to be taken into account for the stability assessment to be valid. In addition, this paper shows that the most accurate stability information can be obtained by means of the determinant related to the associated multivariable impedance ratio. The theoretical findings are also validated by extensive experimental measurements.

Influence of Multilayer Number to Magneto-Impedance Ratio in Electrodeposited [NiFe/Cu]N Multilayer

2020 ◽  
Vol 855 ◽  
pp. 191-196
Author(s):  
Vina Oktaria ◽  
Utari ◽  
Budi Purnama
Keyword(s):  
Magnetic Permeability ◽  
Room Temperature ◽  
Patterned Substrate ◽  
Impedance Ratio ◽  
Result Show ◽  
Impedance Curve

Magneto-impedance ratio of the multilayer [NiFe/Cu)]N study by the number of multilayer. The both sample films of NiFe and Cu are fabricated by electrodeposition methods on a Cu-patterned substrate. The characteristic of magneto-impedance (MI) is performed at room temperature. Magneto-impedance are modified by varying N times (2, 4, 6 and 8) and the measurements frequency. The result show that the typical symetry of the magneto-impedance curve. Then the magneto-impedance (MI) ratio increases with the increase of frequency and N number layers. The increase of the magnetic permeability should address the increase of the MI ratio. Finally, the highest magneto-impedance ratio of 13.79 is obtained for [NiFe (200)/Cu (25)]8 at frequency 100 kHz.

scholarly journals Reactive power optimization strategy considering analytical impedance ratio

2017 ◽  
Author(s):  
Zhongchao Wu ◽  
Weibing Shen ◽  
Jinming Liu ◽  
Maoran Guo ◽  
Shoulin Zhang ◽  
...  
Keyword(s):  
Reactive Power ◽  
Power Optimization ◽  
Optimization Strategy ◽  
Reactive Power Optimization ◽  
Impedance Ratio

scholarly journals New Method to Predict Survival in Hemodialysis Patients Using the Impedance Ratio

2019 ◽  
Vol 28 (1) ◽  
pp. 24-29
Author(s):  
Ender Hur ◽  
◽  
Cenk Gokalp ◽  
Sennur Kose ◽  
Elif Duman ◽  
...  
Keyword(s):  
Hemodialysis Patients ◽  
New Method ◽  
Impedance Ratio
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