scholarly journals Electric Circuit Analysis for PV Array on Short-Circuit Failure of Bypass Diode in PV Module

2019 ◽  
Vol 39 (6) ◽  
pp. 15-25
Author(s):  
Chung-Geun Lee ◽  
Woo-Gyun Shin ◽  
Jong Rok Lim ◽  
Hye-Mi Hwang ◽  
oung-Chul Ju ◽  
...  
Keyword(s):  
Short Circuit ◽  
Electric Circuit ◽  
Circuit Analysis ◽  
Pv Array ◽  
Pv Module ◽  
Bypass Diode

Two-Phase Short Circuit in the Power Grid Powered by a Transformer with a Y/Δ-11 Winding Connection

2020 ◽  
pp. 25-30
Author(s):  
Aleksandr S. Serebryakov ◽  
Vladimir L. Osokin ◽  
Sergey A. Kapustkin
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Relay Protection ◽  
Electric Circuit ◽  
Operational Reliability ◽  
Research Purpose ◽  
Industrial Complex ◽  
Two Phase ◽  
Short Circuit Currents ◽  
Secondary Winding

The article describes main provisions and relations for calculating short-circuit currents and phase currents in a three-phase traction transformer with a star-triangle-11 connection of windings, which feeds two single-phase loads in AC traction networks with a nominal voltage of 25 kilovolts. These transformers provide power to the enterprises of the agro-industrial complex located along the railway line. (Research purpose) The research purpose is in substantiating theoretical equations for digital intelligent relay protection in two-phase short circuits. (Materials and methods) It was found that since the sum of instantaneous currents in each phase is zero, each phase of the transformer works independently. We found that this significantly simplifies the task of analyzing processes with a two-phase short circuit. In this case, the problem of calculating short-circuit currents in the traction network can be simplified by reducing it to the calculation of an ordinary electric circuit with three unknown currents. (Results and discussion) The article describes equations for calculating short-circuit resistances for one phase of the transformer when connecting the secondary winding as a star or a triangle. The currents in the phases of the transformer winding at short circuit for the star-triangle-11 and star-star-with-ground schemes are compared. It was found that when calculating short-circuit currents, there is no need to convert the secondary winding of the traction transformer from a triangle to a star. (Conclusions) It was found that the results of the research can be used in the transition of relay protection systems from electromagnetic relays to modern high-speed digital devices, which will increase the operational reliability of power supply systems for traction and non-traction power consumers.

scholarly journals Study on the Influence of Mounting Dimensions of PV Array on Module Temperature in Open-Joint Photovoltaic Ventilated Double-Skin Façades

2021 ◽  
Vol 13 (9) ◽  
pp. 5027
Author(s):  
Wenjie Zhang ◽  
Tongdan Gong ◽  
Shengbing Ma ◽  
Jianwei Zhou ◽  
Yingbo Zhao
Keyword(s):  
Heat Dissipation ◽  
Temperature Drop ◽  
Vertical Direction ◽  
Wind Pressure ◽  
Pv Array ◽  
Pv Module ◽  
Pv Modules ◽  
Double Skin ◽  
Open Joint ◽  
Double Skin Facades

In building integrated photovoltaics (PV), it is important to solve the heat dissipation problem of PV modules. In this paper, the computational fluid dynamics (CFD) method is used to simulate the flow field around the open-joint photovoltaic ventilated double-skin façades (OJ-PV-DSF) to study the influence of the mounting dimensions (MD) of a PV array on the module temperature. The typical summer afternoon meteorological parameters, such as the total radiation (715.4 W/m2), the outdoor temperature (33.1 °C), and the wind speed (2.0 m/s), etc., are taken as input parameters. With the DO (discrete ordinates) model and the RNG (renormalization-group) k − ε model, a steady state calculation is carried out to simulate the flow of air in and around the cavity under the coupling of hot pressure and wind pressure, thereby obtaining the temperature distribution of the PV array and the wall. In addition, the simulation results are compared with the onsite experimental data and thermal imaging to verify the accuracy of the CFD model. Then three MD of the open joints are discussed. The results show that when the a value (represents the distance between PV modules and wall) changes from 0.05 to 0.15, the temperature drop of the PV module is the most obvious, reaching 2.0 K. When the b value (representing the distance between two adjacent PV modules in the vertical direction) changes from 0 to 0.1, the temperature drop of the PV module is most obvious, reaching 1 K. When the c value (represents the distance between two adjacent PV modules in the horizontal direction) changes from 0 to 0.1, the temperature of the PV module is lowered by 0.8 K. Thus, a = 0.1–0.15, b = 0.1 and c = 0.1 are recommended for engineering applications to effectively reduce the module temperature.

Teaching Short - Circuit Calculation with Off - Nominal Turns Ratio Transformers

TEM Journal ◽  
2021 ◽  
pp. 1525-1533
Author(s):  
Allen A. Castillo ◽  
M. Natalia Galván Osuna ◽  
Norma A. Barboza Tello ◽  
Alejandra J. Vega
Keyword(s):  
Case Studies ◽  
Short Circuit ◽  
Circuit Analysis ◽  
Industrial System ◽  
Software Simulation ◽  
Three Phase ◽  
Short Circuit Calculation ◽  
The Subject ◽  
Ieee Standards ◽  
Short Circuit Analysis

Teaching short-circuit analysis is conducted primarily through case studies; however, there are not many validated short-circuit studies available on the subject, especially when considering off-nominal turns ratio transformers. In order to improve the teaching of short-circuit analysis, a three phase short-circuit study in an industrial system according to ANSI/IEEE standards by means of Zmatrix method is presented; two case studies are considered: the industrial system with nominal and offnominal turns ratio transformers, in both cases the step by step solution is given in an explicit manner and the analytical results are validated through software simulation.

scholarly journals Prediction of Solar Irradiance Based on Artificial Neural Networks

Inventions ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 45 ◽  
Author(s):  
Waleed I. Hameed ◽  
Baha A. Sawadi ◽  
Safa J. Al-Kamil ◽  
Mohammed S. Al-Radhi ◽  
Yasir I. A. Al-Yasir ◽  
...  
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Solar Irradiance ◽  
Open Circuit Voltage ◽  
Low Cost ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Pv Module ◽  
Artificial Neural

Prediction of solar irradiance plays an essential role in many energy systems. The objective of this paper is to present a low-cost solar irradiance meter based on artificial neural networks (ANN). A photovoltaic (PV) mathematical model of 50 watts and 36 cells was used to extract the short-circuit current and the open-circuit voltage of the PV module. The obtained data was used to train the ANN to predict solar irradiance for horizontal surfaces. The strategy was to measure the open-circuit voltage and the short-circuit current of the PV module and then feed it to the ANN as inputs to get the irradiance. The experimental and simulation results showed that the proposed method could be utilized to achieve the value of solar irradiance with acceptable approximation. As a result, this method presents a low-cost instrument that can be used instead of an expensive pyranometer.

scholarly journals Short and open circuit faults study in the PV system inverter

2021 ◽  
Vol 12 (3) ◽  
pp. 1764
Author(s):  
Mohammed Bouzidi ◽  
Abdelkader Harrouz ◽  
Tadj Mohammed ◽  
Smail Mansouri
Keyword(s):  
Short Circuit ◽  
Electric Utility ◽  
Open Circuit ◽  
Photovoltaic System ◽  
Pv System ◽  
Simple Method ◽  
Pv Systems ◽  
Pv Array ◽  
Main Component ◽  
Types Of Faults

<p>The inverter is the principal part of the photovoltaic (PV) systems that assures the direct current/alternating current (DC/AC) conversion (PV array is connected directly to an inverter that converts the DC energy produced by the PV array into AC energy that is directly connected to the electric utility). In this paper, we present a simple method for detecting faults that occurred during the operation of the inverter. These types of faults or faults affect the efficiency and cost-effectiveness of the photovoltaic system, especially the inverter, which is the main component responsible for the conversion. Hence, we have shown first the faults obtained in the case of the short circuit. Second, the open circuit failure is studied. The results demonstrate the efficacy of the proposed method. Good monitoring and detection of faults in the inverter can increase the system's reliability and decrease the undesirable faults that appeared in the PV system. The system behavior is tested under variable parameters and conditions using MATLAB/Simulink.</p>

Sensor of Current or Magnetic Field Based on Magnetoresistance Effect in (La0.7Ca0.3)0.8Mn1.2O3 Manganite Film

2009 ◽  
Vol 154 ◽  
pp. 157-161 ◽  
Author(s):  
V.P. Dyakonov ◽  
S. Piechota ◽  
K. Piotrowski ◽  
A. Szewczyk ◽  
H. Szymczak ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Short Circuit ◽  
Operation Time ◽  
Electric Circuit ◽  
Current Sensor ◽  
Detectable Change ◽  
Magnetoresistance Effect ◽  
Manganite Film ◽  
Current Value ◽  
A Current

The main objective of the performed investigations was to enhance sensitivity of a current sensor to weak changes of magnetic field. New design of the sensor of current based on magnetoresistance effect – MRE (MRE = (RH - R0)/R0 , where RH is the resistance in magnetic field and R0 is the resistance without magnetic field) was developed. The sensor was produced in the form of an annular magnet with a gap, in which the (La0.7Sr0.3)0.8Мn1.2О3 manganite film possessing large negative MRE was inserted. Nominal current in a controllable electric circuit can change from a few tenths parts of ampere to a hundred of amperes. The limit detectable change of current value depends on the size of gap in the annular magnet. The operation time of sensor at current overload and short circuit is less than 0.3 sec. These magnetoresistors are thermally stable over the temperature range from (- 50 ° С) to (+ 50 ° С). Proposed sensors based on MRE can be applied in many electrical arrangements and devices.

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