scholarly journals Degradation processes in tungsten filaments at high temperatures

2021 ◽  
Vol 2119 (1) ◽  
pp. 012139
Author(s):  
Y A Zakharov ◽  
S S Ghots ◽  
T I Sharipov ◽  
R Z Bakhtizin
Keyword(s):  
Low Noise ◽  
Constant Component ◽  
Operating Conditions ◽  
Power Supplies ◽  
Voltage Source ◽  
Degradation Processes ◽  
Joint Influence ◽  
Tungsten Filaments ◽  
Radio Electronics ◽  
Relative Change

Abstract Degradation processes in tungsten filaments of lighting lamps under normal operating conditions are experimentally studied. The duration of each measurement in continuous mode is about 18 hours. To increase the measurement accuracy, subtraction (compensation) of the constant component of the voltage is used. To compensate for the constant component of the voltage, a low noise reference DC voltage source is used. Using this scheme allowed decreasing the influence of the inherent noise of power supplies without suppressing degradation processes. It is shown that the relative change in resistance during the measurement does not exceed 2.8·10−3. It is also shown that the joint influence of voltage fluctuations of power supplies and low noise reference voltage source on the measurement results corresponds to a relative change in a resistance equal to 2.8·10−4. The study of degradation processes can be used to assess the reliability (and durability) of products in electrical engineering and radio electronics.

Analysing integration issues of the microgrid system with utility grid network

2021 ◽  
Vol 22 (1) ◽  
pp. 113-127
Author(s):  
Mulualem Tesfaye ◽  
Baseem Khan ◽  
Om Prakash Mahela ◽  
Hassan Haes Alhelou ◽  
Neeraj Gupta ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Control Mode ◽  
Voltage Source ◽  
Modulation Scheme ◽  
Main Challenge ◽  
Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

New Method to Determine the a-Si:H Pin Diode Series Resistance by Noise Measurements

1998 ◽  
Vol 507 ◽  
Author(s):  
F. Blecher ◽  
K. Seibel ◽  
M. Hillebrand ◽  
M. Böhm
Keyword(s):  
Series Resistance ◽  
Partial Information ◽  
Low Noise ◽  
Operating Conditions ◽  
New Method ◽  
Measuring System ◽  
Pin Diode ◽  
Noise Current ◽  
Current Voltage ◽  
Noise Measurements

ABSTRACTThe series resistance limits the linearity of photodiodes and decreases the efficiency of solar cells. It is usually determined from IV-measurements for moderate and high forward current density. This method, however, provides only partial information about Rs, since the series resistance depends on the operating point. An alternative method is based on noise measurements. System noise of the measuring system with a low-noise current-voltage converter has been investigated. A new method for extraction of photodiode series resistance from noise measurements is suggested. Noise measurements are carried out for a-Si:H pin diodes. The series resistance of an amorphous pin diode has been extracted for different operating conditions using the new measurement method.

Gain-ranging analog or digital seismic system

1974 ◽  
Vol 64 (1) ◽  
pp. 103-113 ◽  
Author(s):  
E. R. Kanasewich ◽  
W. P. Siewert ◽  
M. D. Burke ◽  
C. H. McCloughan ◽  
L. Ramsdell
Keyword(s):  
Dynamic Range ◽  
Wide Band ◽  
Low Noise ◽  
Active Filters ◽  
Operating Conditions ◽  
Natural Period ◽  
Analog System ◽  
Effective Dynamic ◽  
Different Levels ◽  
Seismic System

abstract A wide-band, gain-ranging amplifier is described that may be used for recording data with a dynamic range of 60 db in each of three different levels, 12 db apart, so that we achieve an “effective” dynamic ±160-v analog or 84-db digital, within a normal ±10-v analog system. As described, the ranging circuit reduces the gain of the amplifier by a factor of either 4 or 16 whenever the output signal approaches the maximum for the system. The wide-band response is achieved with low-noise operational amplifiers and second-order active filters. Signals with periods greater than 30 sec are amplified by 100 db and those with periods shorter than 1 sec are amplified by 70 db. The system works well in extending the useful output range of a Willmore Mark II seismometer with a natural period of 1.5 sec to over 40 sec under normal field operating conditions. When analog recording, the gain-range switching occurs when the input signal reaches ±8.1-v; when digital recording, the level is ±9.375 v. The period in a divide-by-4- or 16-state is preset by the experimentalist. The gain level is recorded on an extra channel which is also used to record absolute time.

Improving Gerotor Pump Performance Trough Design, Modeling and Simulation

2021 ◽  
Author(s):  
Lozica Ivanović ◽  
Miloš Matejić
Keyword(s):  
Low Noise ◽  
Operating Conditions ◽  
Design Parameters ◽  
Pump Efficiency ◽  
Hydraulic Systems ◽  
Wear Process ◽  
Gerotor Pump ◽  
Gerotor Pumps ◽  
Negative Effect ◽  
Compact Design

Gerotor pumps are well known by a compact design, simple structure and low noise level, which makes them suitable for use in the automotive industry, and especially in hydraulic systems for engine lubrication. One of the main disadvantages of gerotor pumps is the inability to adjust to wear, which significantly reduces the pump efficiency. In order to mitigate the negative effect of the inevitable wear process, this paper presents a methodology for determining the optimal combination of trochoid gears design parameters for a defined aspect. An appropriate mathematical model has been developed to analyze the effect of changes in gear design parameters in relation to maximum contact stresses, pressure changes in gerotor pump chambers and wear rate proportional factor (WRPF). Verification of the developed models was performed by realizing physical pairs of gears and laboratory experiments with simulation of pump operating conditions. The results and conclusions presented in this paper, with an emphasis on the actual work processes, bring very important perspectives for the gerotor pumps design with improved performance.

Adaptive SRF-PLL Based Voltage and Frequency Control of Hybrid Standalone WECS with PMSG-BESS

2018 ◽  
Vol 19 (6) ◽  
Author(s):  
Anjana Jain ◽  
R. Saravanakumar ◽  
S. Shankar ◽  
V. Vanitha
Keyword(s):  
Reactive Power ◽  
Frequency Control ◽  
Storage System ◽  
Synchronous Generator ◽  
Energy Storage System ◽  
Voltage Regulation ◽  
Operating Conditions ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Control Scheme

Abstract The variable-speed Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) attracts the maximum power from wind, but voltage-regulation and frequency-control of the system in standalone operation is a challenging task A modern-control-based-tracking of power from wind for its best utilization is proposed in this paper for standalone PMSG based hybrid-WECS comprising Battery Energy Storage System (BESS). An Adaptive Synchronous Reference Frame Phase-Locked-Loop (SRF-PLL) based control scheme for load side bi-directional voltage source converter (VSC) is presented for the system. MATLAB/Simulink model is developed for simulation study for the proposed system and the effectiveness of the controller for bi-directional-converter is discussed under different operating conditions: like variable wind-velocity, sudden load variation, and load unbalancing. Converter control scheme enhances the power smoothening, supply-load power-matching. Also it is able to regulate the active & reactive power from PMSG-BESS hybrid system with control of fluctuations in voltage & frequency with respect to varying operating conditions. Proposed controller successfully offers reactive-power-compensation, harmonics-reduction, and power-balancing. The proposed scheme is based on proportional & integral (PI) controller. Also system is experimentally validated in the laboratory-environment and results are presented here.

scholarly journals Analysis of Capacitance to Ground Formulas for Different High-Voltage Electrodes

Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1090 ◽  
Author(s):  
Jordi-Roger Riba ◽  
Francesca Capelli
Keyword(s):  
High Voltage ◽  
Fem Simulation ◽  
Operating Conditions ◽  
Power Supplies ◽  
Measuring Instruments ◽  
Stray Capacitance ◽  
Analytical Formulas ◽  
Circular Rings ◽  
Available Information ◽  
Limited Scope

Stray capacitance can seriously affect the behavior of high-voltage devices, including voltage dividers, insulator strings, modular power supplies, or measuring instruments, among others. Therefore its effects must be considered when designing high-voltage projects and tests. Due to the difficulty in measuring the effects of stray capacitance, there is a lack of available experimental data. Therefore, for engineers and researchers there is a need to revise and update the available information, as well as to have useful and reliable data to estimate the stray capacitance in the initial designs. Although there are some analytical formulas to calculate the capacitance of some simple geometries, they have a limited scope. However, since such formulas can deal with different geometries and operating conditions, it is necessary to assess their consistency and applicability. This work calculates the stray capacitance to ground for geometries commonly found in high-voltage laboratories and facilities, including wires or rods of different lengths, spheres and circular rings, the latter ones being commonly applied as corona protections. This is carried out by comparing the results provided by the available analytical formulas with those obtained from finite element method (FEM) simulation, since field simulation methods allow solving such problem. The results of this work prove the suitability and flexibility of the FEM approach, because FEM models can deal with wider range of electrodes, configurations and operating conditions.

scholarly journals Active and Reactive Power Compensation Control Strategy for VSC-HVDC Systems under Unbalanced Grid Conditions

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3140 ◽  
Author(s):  
Weiming Liu ◽  
Tingting Zheng ◽  
Ziwen Liu ◽  
Zhihua Fan ◽  
Yilong Kang ◽  
...  
Keyword(s):  
Control Strategy ◽  
Disturbance Observer ◽  
Reactive Power ◽  
Operating Conditions ◽  
Voltage Source ◽  
Double Frequency ◽  
Compensation Control ◽  
Active And Reactive Power ◽  
Passivity Based Control ◽  
Unbalanced Grid

This paper presents a power compensation strategy to suppress the double frequency power ripples of Voltage source converter high-voltage direct current (VSC-HVDC) systems under unbalanced grid voltage conditions. The mathematical control equations of the double frequency ripple power of VSC under unbalanced operating conditions are firstly derived and established, where the dynamic behaviors of the double frequency ripples in active and reactive power are regarded as being driven by current-relevant components and voltage-relevant components, respectively. Based on the equations, a power compensation control strategy of VSC-HVDC is proposed via the passivity-based control with disturbance observer to suppress both the current-relevant and voltage-relevant components in the power ripples. With this control strategy, the double frequency ripples in active and reactive power are suppressed simultaneously and system performance is significantly enhanced with the implementation of the disturbance observer in the passivity-based control. Theoretical stability analysis and simulation cases show the effectiveness and superiority of the proposed strategy.

scholarly journals Single Event Effect Analysis of SiGe Low Noise Amplifier

2021 ◽  
Vol 25 (2) ◽  
pp. 57-64
Author(s):  
Manel Bouhouche ◽  
◽  
Saida Latreche ◽  
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Low Noise ◽  
Operating Conditions ◽  
Low Noise Amplifier ◽  
Radiation Tolerance ◽  
Single Event ◽  
Effect Analysis ◽  
Sige Hbt ◽  
High Let ◽  
Noise Amplifier

This paper analyzes the single event transient (SET) response of low noise amplifier (LNA) designed using SiGe heterojunction bipolar transistors (HBT). To verify the radiation tolerance of the proposed LNA, a total of four cascode configurations were designed. Comprehensive mixed-mode simulations were performed to evaluate the SET susceptibility of considered LNA cascode configurations, and we have analyzed how the strike parameters affect their output response. In this fact the strike position, linear energy transfer (LET), and track radius, were varied, and the resulting transients were compared for the different LNA configurations. Through this study, the potential capability of the inverse mode SiGe heterojunction bipolar transistor (HBT) in LNA radiation tolerance was confirmed for various strike operating conditions. It has been demonstrated that the single event sensitivity was reduced for LNA employing inverse mode SiGe HBT for strike device. The strike influence on the different LNA configurations response depends on strike LET, where a reduced SET variation is observed for high LET.

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