The Study of Inner EM Environment in the Helicopter under the Influence of Lightning Strikes

2014 ◽  
Vol 912-914 ◽  
pp. 860-864
Author(s):  
Yan De Wang ◽  
Cheng Gao ◽  
Fei Guo ◽  
Yan Xin Li
Keyword(s):  
Simulation Analysis ◽  
Current Waveform ◽  
Lightning Strikes ◽  
Lightning Current ◽  
Numeric Simulation ◽  
Environment Characteristic

Numeric simulation of the whole aircraft is conducted in the CST MICROSTRIPES workshop which is based on the theory of TLM. The current waveform is defined according to the standard of SAEARP5412. The EM environment inside the helicopter is analyzed when the lightning strikes on the middle of the helicopter vertically. The lightning current moves along the aircraft to the back, then travels to the middle along the line. Simulation analysis demonstrates that the method can effectively simulate the indirect lightning effect, and shows the EM environment characteristic inside the helicopter.

scholarly journals Direct Lightning Current Measurements in Southeastern Brazil I. Current Waveform

1997 ◽  
Author(s):  
M. Lacerda ◽  
O. Pinto Jr. ◽  
I.R.C.A. Pinto ◽  
J.H. Diniz ◽  
A.M. Carvalho
Keyword(s):  
Southeastern Brazil ◽  
Current Waveform ◽  
Lightning Current

scholarly journals Calculation of lightning surges on the high voltage lines. Case of 220 kV line: Ngo -Brazzaville in Congo

2017 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Rodolphe Gomba ◽  
Alphonse Omboua
Keyword(s):  
Power Lines ◽  
Protective Equipment ◽  
Worst Case ◽  
Lightning Strikes ◽  
Lightning Current ◽  
Wave Forms ◽  
Lightning Discharges ◽  
Voltage Wave ◽  
High Level ◽  
Insulation Coordination

The importance of line Ngo-Brazzaville (220 kV, 207 km) requires operators to avoid cuts that can increase the risk of instability. We see it is quite rare that a storm that occurs in areas crossed by this line will not cause triggering. Note that due to lightning discharges are the main causes of unscheduled outages of Congo's power lines; we ignore this during the peak values of voltage wave forms that result. In regions with high level keraunic like Congo, reducing insulation failures due to lightning is a concern in the management of overheads lines. This article clarifies the peak values of the voltages that can be achieved on the network in order to build the operators as to the precautions on the insulation coordination of protective equipment related to lightning. For these calculations surge of atmospheric origin (case of lightning), we considered the bi-exponential function and Heidler function for modeling the wave of the lightning current. This methodology led us to specially treat the effects of direct lightning strikes that constitute the worst case because they generate most destructive shock wave that indirect lightning strikes.

The Effect of Lightning Strikes on Bismaleimide Composites by Dynamic Mechanical Analysis

2011 ◽  
Vol 179-180 ◽  
pp. 449-454
Author(s):  
Dong Bing Geng ◽  
Hong Jun Guo ◽  
San Qing Zhang
Keyword(s):  
Glass Transition ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Cross Link ◽  
Lightning Strikes ◽  
Dynamic Mechanical ◽  
Lightning Current ◽  
Link Density ◽  
Cross Link Density ◽  
Composite Samples

In this paper, a new method that has shown significant potential to characterize lightning strikes damage which is couple with dynamic mechanical analysis. The composite samples used in this work are based on carbon fiber/bismaleimide system. The analysis of the dynamic mechanical data demonstrate the glass transition temperature of the composites increased as a function of increasing lightning current , simultaneity with the presence ofpotential damage, whichare result in higher network cross-link density and the incipent degradation of the polymer matrix.

scholarly journals De-noising the CN Tower lightning current signal using short term Fourier transform-based spectral substraction

2021 ◽  
Author(s):  
Mohammed Jahirul Islam
Keyword(s):  
Fourier Transform ◽  
Spectral Subtraction ◽  
Current Signal ◽  
Current Waveform ◽  
Transmission Tower ◽  
Subtraction Method ◽  
Short Term ◽  
Lightning Current ◽  
Spectral Subtraction Method ◽  
Current Derivative

The CN Tower is a transmission tower and it is not unexpected that recorded lightning current signals be corrupted by noise. The existence of noise may affect the calculation of current waveform parameters (current peak, 10-90% risetime to current peak, maximum steepness, and pulse width at half value of current peak). But accurate statistics of current waveform parameters are required to design systems for the protection of structures and devices, especially those with electrical and electronic components, exposed to hazards of lightning. Since more electrical devices are used nowadays, lightning protection becomes more important. So to determine accurate statistics of current waveform parameters, the interfering noise must be removed. In this thesis we describe a technique for de-noising the CN Tower lightning current by modifying its Fourier Transform (FT) where a simulated current waveform (Heidler function) is used to represent the lightning current signal.The limitations of Discrete Fourier Transform (DFT) for removal of non-stationary noise signals, including the noise connected with CN Tower lightning current signals and its properties are discussed. The Short Term Fourier Transform (STFT) is explored to analyze non-stationary signals and to deal with the limitations of DFT. Last of all, an STFT-based Spectral Subtraction method is developed to denoise the CN Tower lightning current signal. In order to evaluate the Spectral Subtraction method, a simulated current derivative waveform ( obtained by differentiating Heidler function) is artificially distorted by a noise signal measured at the CN Tower in the absence of lightning. The Spectral Subtraction method is then used to de-noise the distorted waveform. The de-noised waveform proved to be very close to the original simulated waveform. A signal-peak to noise-peak ratio (SPNPR) of the CN Tower lightning current signal is defined and calculated before and after the de-noising process. For example, for a typical measured current derivative signal, the SPNPR before de-noising is 7.27, and after de-noising it becomes 151.30. Similarly for its current waveform (obtained by numerical integration) the SPNPR before de-noising is 20,16 and it becomes 361.39 after de-noising. Statistics of current waveform parameters are obtained from the de-noised waveforms. The Spectral Subtraction method is also applied for de-noising the electric and magnetic field waveforms generated by lightning to the CN Tower which enables the calculation of their waveform parameters.

scholarly journals Numerical Study of Lightning Protection of Wind Turbine Blade with De-Icing Electrical Heating System

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 691
Author(s):  
Yang Zhao ◽  
Xi Wang ◽  
Qibin Zhou ◽  
Zhenxing Wang ◽  
Xiaoyan Bian
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Numerical Study ◽  
Heating System ◽  
Wind Turbine Blade ◽  
Electrical Heating ◽  
Electromagnetic Transients ◽  
Lightning Protection ◽  
Lightning Strikes ◽  
Lightning Current

In order to solve the problem of icing on the surface of wind turbine blade, a heating system that includes a carbon fiber net (CFN) and power cables is proposed recently. When lightning strikes at the blade with a de-icing heating system, the blade and its heating system are more easily damaged due to the overvoltage between the lightning protection system (LPS) of the blade and the heating system. In this paper, the models of a wind turbine blade with the de-icing heating system are established by Alternative Transients Program/Electromagnetic Transients Program (ATP–EMTP) and the accuracy of models is verified through an experiment. With these models, the influence of lightning current, surge protective devices (SPDs) and earthing resistance of wind turbine are analyzed by calculating the voltage between the down-conductor of the LPS and the heating system. The results show that the voltage is positively correlated with lightning current amplitude and negatively correlated with the front time of lightning current. SPDs are quite useful to reduce the voltage, and an optimal installation scheme of SPDs is obtained by simulation. It is noted that voltage decreases slightly with the increasing earthing resistance with the optimal installation scheme of SPDs.

scholarly journals Determination of Cumulative Distribution Function of the Crest Value of the Lightning Current Circulating Through Line Surge Arresters

2020 ◽  
Vol 69 (2) ◽  
pp. 11-18
Author(s):  
Goran Levačić ◽  
Alain Xémard ◽  
Miroslav Mesić
Keyword(s):  
Distribution Function ◽  
Transmission Line ◽  
Transmission Lines ◽  
Cumulative Distribution Function ◽  
Cumulative Distribution ◽  
Lightning Strikes ◽  
Surge Arresters ◽  
Lightning Current ◽  
Calculation Results

For the selection and design of line surge arresters (LSA), it is essential to know the characteristics of the lightning current circulating through LSA. When lightning strikes a transmission line, only a part of the lightning current circulates through LSA.This part mostly depends on the point of impact, and the characteristic of the lightning stroke current. The determination of the cumulative distribution function of the lightning current circulating through arresters is presented in first part of the paper. It can be applied on transmission lines where LSAs will be installed to protect the line against the effect of atmospheric discharges.Second part of paper presents the calculation results of the cumulative distribution function of the lightning current circulating through arresters for particular 110 kV transmission line located in an area with high lightning activity.

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