Analytical and Experimental Studies on Induced Current Switching by a Fault-Proof Gas Insulated Earthing Switch

2010 ◽  
Vol 11 (5) ◽  
Author(s):  
Mandava Mohana Rao ◽  
Moutusi Paul ◽  
H.S. Jain
Keyword(s):  
Short Circuit ◽  
Experimental Studies ◽  
Short Circuit Current ◽  
Design Parameters ◽  
Induced Current ◽  
Current Switching ◽  
Test Circuit ◽  
Reliable Performance ◽  
Gas Insulated Substation ◽  
The Impact

Fault-proof earthing switches are one of the important modules of a gas insulated substation, as it enables make at 100 percent short circuit current, which is functionally different from maintenance earthing switches. The fault-proof earthing switch shall be designed to make and break electro-magnetically and electro-statically induced currents as per IEC-62271-102. The paper discusses the impact of “test circuit configurations and voltage” on test parameters for gas insulated fault-proof earthing switch utilizing simulation with PSCAD software. Authors record the development of a 145 kV gas insulated fault proof earthing switch by considering novel design features like minimum arcing/pre-arcing time, effective current transfer from arcing contact to ground terminal, etc. The development has been evaluated successfully for electro-magnetically and electro-statically induced current duties as per IEC. Finally, design parameters to be considered for ensuring reliable performance during induced current switching from fault-proof earthing switches are also discussed.

Research of Large-Scale Offshore Wind Farm Collection System Short Circuit Equivalent Network

2013 ◽  
Vol 448-453 ◽  
pp. 1732-1737
Author(s):  
Liu Bin ◽  
Hong Wei Cui ◽  
Li Xu ◽  
Kun Wang ◽  
Zhu Zhan ◽  
...  
Keyword(s):  
Large Scale ◽  
Wind Farm ◽  
Short Circuit ◽  
Short Circuit Current ◽  
System Optimization ◽  
Offshore Wind ◽  
Offshore Wind Farm ◽  
Collection System ◽  
Medium Voltage ◽  
The Impact

This paper analyses the characteristics of large-scale offshore wind farm collection network and the impact of the medium voltage collection system optimization,while from the electrical technology point,it proposes the short circuit current of the collection network computational model and algorithms,based on the principle of equivalent circuit.Taking a wind power coolection system planned for a certain offshore wind farm planning for example, the validity of the model and algorithm is verified.

scholarly journals Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

2018 ◽  
Author(s):  
Jan Mihalyovics ◽  
Christian Brück ◽  
Dieter Peitsch ◽  
Ilias Vasilopoulos ◽  
Marcus Meyer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Experimental Studies ◽  
Total Pressure Loss ◽  
Design Parameters ◽  
Flow Conditions ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Impact ◽  
Stator Design

The objective of the presented work is to perform numerical and experimental studies on compressor stators. This paper presents the modification of a baseline stator design using numerical optimization resulting in a new 3D stator. The Rolls Royce in-house compressible flow solver HYDRA was employed to predict the 3D flow, solving the steady RANS equations with the Spalart-Allmaras turbulence model, and its corresponding discrete adjoint solver. The performance gradients with respect to the input design parameters were used to optimize the stator blade with respect to the total pressure loss over a prescribed incidence range, while additionally minimizing the flow deviation from the axial direction at the stator exit. Non-uniform profile boundary conditions, being derived from the experimental measurements, have been defined at the inlet of the CFD domain. The presented results show a remarkable decrease in the axial exit flow angle deviation and a minor decrease in the total pressure loss. Experiments were conducted on two compressor blade sets investigating the three-dimensional flow in an annular compressor stator cascade. Comparing the baseline flow of the 42° turning stator shows that the optimized stator design minimizes the secondary flow phenomena. The experimental investigation discusses the impact of steady flow conditions on each stator design while focusing on the comparison of the 3D optimized design to the baseline case. The flow conditions were investigated using five-hole probe pressure measurements in the wake of the blades. Furthermore, oil-flow visualization was applied to characterize flow phenomena. These experimental results are compared with the CFD calculations.

Effect of luminal acidity on the apical cation channel in rabbit esophageal epithelium

2007 ◽  
Vol 292 (3) ◽  
pp. G796-G805 ◽  
Author(s):  
N. A. Tobey ◽  
C. M. Argote ◽  
M. S. Awayda ◽  
X. C. Vanegas ◽  
R. C. Orlando
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Acid Reflux ◽  
Cation Channel ◽  
Esophageal Epithelium ◽  
Protective Function ◽  
Membrane Area ◽  
Luminal Ph ◽  
The Impact

Esophageal epithelial cells contain an apical cation channel that actively absorbs sodium ions (Na+). Since these channels are exposed in vivo to acid reflux, we sought the impact of high acidity on Na+channel function in Ussing-chambered rabbit epithelium. Serosal nystatin abolished short-circuit current ( Isc) and luminal pH titrated from pH 7.0 to pH ≥ 2.0 had no effect on Isc. Circuit analysis at pH 2.0 showed small, but significant, increases in apical and shunt resistances. At pH < 2.0, Iscincreased whereas resistance ( RT) decreased along with an increase in fluorescein flux. The change in Isc, but not RT, was reversible at pH 7.4. Reducing pH from 7.0 to 1.1 with H2SO4gave a similar pattern but higher Iscvalues, suggesting shunt permselectivity. A 10:1 Na+gradient after nystatin increased Iscby ∼4 μAmps/cm2and this declined at pH ≤ 3.5 until it reached ∼0.0 at pH 2.0. Impedance analysis on acid-exposed (non-nystatin treated) tissues showed compensatory changes in apical (increase) and basolateral (decrease) resistance at modest luminal acidity that were poorly reversible at pH 2.0 and associated with declines in capacitance, a reflection of lower apical membrane area. In esophageal epithelium apical cation channels transport Na+at gradients as low as 10:1 but do not transport H+at gradients of 100,000:1 (luminal pH 2.0). Luminal acid also inhibits Na+transport via the channels and abolishes it at pH 2.0. These effects on the channel may serve as a protective function for esophageal epithelium exposed to acid reflux.

The Impact of Synchronous Distributed Generation (DG) on Distribution System

2015 ◽  
Vol 785 ◽  
pp. 388-392 ◽  
Author(s):  
Hasmaini Mohamad ◽  
Shahrani Shahbudin ◽  
Nofri Yenita Dahlan
Keyword(s):  
Distributed Generation ◽  
Distribution System ◽  
System Performance ◽  
Power Flow ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Voltage Profile ◽  
Before And After ◽  
Potential Benefits ◽  
The Impact

Interconnection of Distributed Generation (DG) in distribution system presents many potential benefits as well as drawbacks. The impacts of DG might vary with the types of generator. This paper presents a study on the impacts of synchronous DG's interconnection in distribution system. Steady state analysis is carried out to analyze the impact of DG on voltage profile and short circuit current considering before and after DG interconnection. Dynamic analysis is also performed for investigating the performance of DG when a part of distribution system is being islanded. Results show that the penetration of DG contributes to the changes of power flow in the system, hence give impacts to the overall system performance.

scholarly journals Fault Assessment and Mitigation of the 132kV Transmission Line in Nigeria using Improved Resonant Fault Current Limiting (RFCL) Protection Scheme

2018 ◽  
Vol 3 (10) ◽  
pp. 38-44
Author(s):  
D. C. Idoniboyeobu ◽  
S. L. Braide ◽  
Wigwe Elsie Chioma
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Resonant Circuit ◽  
Fault Current ◽  
Protection Scheme ◽  
Current Limiting ◽  
Simulation Results ◽  
The Impact

This research work proposed an improved Resonant Fault Current Limiting (RFCL) protection scheme to reduce the impact of three-phase short-circuit faults in a power system sub-transmission network. The model used an interpolator-extrapolator technique based on a Resonant Fault Current Limiter (RFCL) for automating the procedure of predicting the required reactor value that must be in resonant circuit to limit the short-circuit current values to permissible values. Using the developed model, short-circuit fault simulations on the three phases of the transmission line (Phase A-C) were performed in the MATLAB-SIMULINK environment. Simulation results were obtained by varying the resonant inductance (reactor) parameter of the RFCL circuit for each of the phases to obtain permissible short-circuit current levels and the values used to program a functional interpolator-extrapolator in MATLAB; the resonant values were typically set to values of inductance equal to 0.001H, 0.01H and from 0.1H to 0.5H in steps of 0.1H. Simulation results revealed the presence of very high short-circuit current levels at low values of the resonant inductor. From the results of simulations, there are indications that the RFCL approach is indeed very vital in the reduction of the short circuit current values during the fault and can safeguard the circuit breaker mechanism in the examined power system sub-transmission system. In addition, lower fault clearing times can be obtained at higher values of inductances; however, the clearance times start to converge at inductance values of 0.1H and above.

scholarly journals Design and Analysis of Gallium Nitride-Based p-i-n Diode Structure for Betavoltaic Cell with Enhanced Output Power Density

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1100
Author(s):  
Young Jun Yoon ◽  
Jae Sang Lee ◽  
In Man Kang ◽  
Jung Hee Lee ◽  
Dong Seok Kim
Keyword(s):  
Gallium Nitride ◽  
Power Density ◽  
Output Power ◽  
Computer Aided Design ◽  
Short Circuit ◽  
Reverse Current ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Design Parameters ◽  
Trap States

In this work, Gallium Nitride (GaN)-based p-i-n diodes were designed using a computer aided design (TCAD) simulator for realizing a betavoltaic (BV) cell with a high output power density (Pout). The short-circuit current density (JSC) and open-circuit voltage (VOC) of the 17 keV electron-beam (e-beam)-irradiated diode were evaluated with the variations of design parameters, such as the height and doping concentration of the intrinsic GaN region (Hi-GaN and Di-GaN), which influenced the depletion width in the i-GaN region. A high Hi-GaN and a low Di-GaN improved the Pout because of the enhancement of absorption and conversion efficiency. The device with the Hi-GaN of 700 nm and Di-GaN of 1 × 1016 cm−3 exhibited the highest Pout. In addition, the effects of native defects in the GaN material on the performances were investigated. While the reverse current characteristics were mainly unaffected by donor-like trap states like N vacancies, the Ga vacancies-induced acceptor-like traps significantly decreased the JSC and VOC due to an increase in recombination rate. As a result, the device with a high acceptor-like trap density dramatically degenerated the Pout. Therefore, growth of the high quality i-GaN with low acceptor-like traps is important for an enhanced Pout in BV cell.

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