scholarly journals Computation of Transient Voltages on the Interconnected Grounding Grids

2020 ◽  
Author(s):  
Walter Luiz Manzi de Azevedo ◽  
Anderson Ricardo Justo de Araújo ◽  
José Pissolato Filho
Keyword(s):  
Transmission Line ◽  
Power Plants ◽  
Electromagnetic Transients ◽  
Electrical System ◽  
Reliable Operation ◽  
Natural Conditions ◽  
Lightning Strikes ◽  
Grounding Grids ◽  
Transient Voltage ◽  
Transient Voltages

Grounding grids play a fundamental role to provide safety during electromagnetic transients and reliable operation of any electrical system under normal conditions. In this context, when lightning strikes a transmission line, surge currents will propagate to the electrical substations where grounding grids must dissipate these impulsive currents into the soil. Grounding grids are composed of horizontal bars welded with vertical forming a large mesh. Additionally, the interconnected grids are largely employed to guarantee safety for personnel and equipment in facilities. Due to several natural conditions, horizontal bars can be damaged and compromise the performance of the grounding grid in power plants. In this paper, transient voltages are computed for whole and damaged grids when lightning strikes a transmission line. Results have shown that there is a difference in the transient voltage peaks in these two conditions. To decrease these voltages, vertical rods are installed in the border of the grounding grids, which has been shown as an effectivesolution to lower these voltage peaks in the damaged grounding grids.

scholarly journals Comparative Analysis of Measures and Technical Means for Suppressing the Aperiodic Current Component in Circuit Breaker

2021 ◽  
Vol 64 (4) ◽  
pp. 314-327
Author(s):  
V. V. Kuchanskyi
Keyword(s):  
Transmission Line ◽  
High Voltage ◽  
Power Plants ◽  
Circuit Breaker ◽  
Electromagnetic Transients ◽  
Current Component ◽  
Large Power ◽  
Specific Investment ◽  
Aperiodic Component ◽  
Extra High Voltage

Electromagnetic transients are considered in the implementation of three-phase automatic reclose on the transmission line of extra high voltage 750 kV. The influence of automatic shunting of phases and pre-insertion active resistance for limiting the characteristics of the aperiodic component of the current, which obstructs the transition of full current through zero, is evaluated. The paper analyses measures taking into account the effect of changing the degree of compensation of charging power and the angles of switching on an SF6 circuit breaker. Sub-schemes of disconnected undamaged phases of the extra high voltage transmission line for the investigation of the aperiodic current component have been developed. The values of the pre-insertion active resistances of different connection and automatic shunting of the phases are determined at which there is an effective reduction of the characteristics of the aperiodic component of the current. In the software environment, a model was developed and switching transient processes were simulated in the 750 kV transmission line. Operating modes that are potentially dangerous for SF6 circuit breakers are determined and recommendations are given to avoid them. Currently the technical and economic requirements for power transmission lines designed for the transport of electricity from large power plants and for the communication of powerful energy systems are increasing. Today there is the importance of reducing specific investment in the construction of new and reconstruction of existing lines. The solution of these issues is associated with the maximum use of power lines by increasing their power transfer capability and controlling modes, especially in operating emergency conditions and post-emergency operation of power systems.  

Transient Voltages on Grounding Grids buried in Stratified Soils

2020 ◽  
Author(s):  
Anderson Anderson R. J. de Araújo ◽  
Walter L. M. de Azevedo ◽  
José Pissolato Filho ◽  
Jaimis S. L. Colqui ◽  
Sérgio Kurokawa
Keyword(s):  
Power Systems ◽  
Electric Circuit ◽  
Lightning Strikes ◽  
Vector Fitting ◽  
Full Wave ◽  
Vertical Electrode ◽  
Radiation Theory ◽  
Lightning Discharges ◽  
Grounding Grids ◽  
Transient Voltages

Grounding grids (GG) play a fundamental role in the protection of personnel and prevention of damages in equipment during surge transients on substations caused by lightning discharges on power systems. In this context, a precise GG modeling must consider several factors such as the arrangement and the soil compacted in stratified layers. This paper proposes a lumped approach for GG buried in several stratified soils to compute the transient node voltages when subjected to lightning strikes. The vertical and horizontal electrodes are modelled separately by lumped circuit approach. The vertical electrode impedances buried in a stratified soil are computed by the numerical Method of Moments (MoM) in the full-wave electromagnetic software FEKOR , directly in frequency domain, and then, an electric circuit is obtained by the Vector Fitting technique. The horizontal electrodes are modelled based on the electromagnetic radiation theory, where each segment of the electrode can be regarded as a lamental currentcarrying conductor. Lightning currents of fast and slow-front waveforms, are employed in the simulations. Results show that when stratified soils are considered, the differences of the transient voltage peaks, in comparison with the ones calculated for the homogeneous soil is more pronounced as the thickness of soil decreases.

A Comparative Analysis of Using the pH and Ammonia Calculation Algorithms in the Chemical Monitoring Systems at Thermal Power Plants

Vestnik MEI ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 37-42
Author(s):  
Olga V. Yegoshina ◽  
◽  
Sofiya K. Zvonareva ◽  
Wei Lin Htet ◽  
◽  
...  
Keyword(s):  
Chemical Control ◽  
Power Plants ◽  
Thermal Power ◽  
Ammonia Concentration ◽  
Monitoring Systems ◽  
Mechanical Equipment ◽  
Reliable Operation ◽  
Chemical Monitoring ◽  
Calculation Algorithms ◽  
Comparison Of The Results

The reliability of thermal and mechanical equipment is largely associated with the introduction of cycle chemistry monitoring systems (CCMS). It is the operation of these systems that helps maintain the main parameters within the standardized ranges in a significantly more reliable manner and decrease the failure rate at power plants. Modern CCMSs use, as input information, the data of automatic chemical monitoring, laboratory chemical control, and thermal process parameters. Unfortunately, the large volume of chemical monitoring performed with the help of laboratory chemical control analyzers is a factor that causes less reliable operation of CCMS. The present study is intended for operating staff and employees of design organizations with the aim to decrease the volume of laboratory chemical control and reduce the sampling points load in terms of sampling flowrate. The possibility of applying indirect algorithms for calculating the most widely used indicators, such as pH and ammonia concentration, based on electrical conductivity measurements of direct and H-cationated samples in automatic chemical monitoring systems is considered. The results of calculation carried out using three algorithms for pH and ammonia concentration for laboratory and field conditions are given. A comparison of the results obtained from using three different methods for calculating the standardized indicators proceeding from experimental data is carried out.

scholarly journals Effect of indirect lightning strike to 66kV transmission line in Java-Bali system

2018 ◽  
Vol 197 ◽  
pp. 11001
Author(s):  
Aristo Adi Kusuma ◽  
Putu Agus Aditya Pramana ◽  
Brian Bramantyo S.D.A. Harsono ◽  
Buyung Sofiarto Munir
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Lightning Strike ◽  
Actual Condition ◽  
Peak Current ◽  
Lightning Strikes ◽  
Detection Systems ◽  
Current Magnitude ◽  
Lightning Detection ◽  
Insulator Flashover

Based on Java-Bali grid disturbance data, the 66kV transmission lines that is close to or intersect with 150kV or 500kV transmission line is often experienced earth fault due to insulator flashover. The insulator flashover can be caused by indirect lightning strike since lightning strikes tend to strike higher structure. Therefore, this paper will determine the effect of indirect lightning strike on 150kV or 500kV transmission line to 66kV transmission line by modeling and simulation using application of transient analysis. Variation of lightning peak current magnitude and gap between 66kV transmission line and transmission line with higher voltage is performed during simulation. The range of peak current magnitude follows the data from lightning detection systems, while the value of gap follows the data from actual condition. It is found that higher current peak and closer gap will cause higher transient overvoltage on insulator of 66kV transmission line thus insulator flashover may occur more frequent. Addition of earth wire on 66kV transmission line and gap between each transmission by organizing the sag of conductor can be performed to minimize the insulator flashover.

scholarly journals Performance Comparative Analysis of Monocrystalline and Polycrystalline Single Diode Solar Panel Models using the Five Parameters Method

2019 ◽  
Vol 1 (1) ◽  
pp. 14
Author(s):  
Rizal Akbarudin Rahman ◽  
Aripriharta Aripriharta ◽  
Hari Putranto
Keyword(s):  
Renewable Energy ◽  
Input Data ◽  
Power Plants ◽  
Renewable Energy Sources ◽  
Solar Panel ◽  
Solar Panels ◽  
Natural Conditions ◽  
Panel Models ◽  
The Cost ◽  
Module Performance

The use of renewable energy as a source of electrical energyincreases every year. Unfortunately, Indonesia does not have manypower plants that utilize renewable energy sources. The mostpotential renewable energy in Indonesia is the sunlight with the helpof solar panels that converts solar energy into electrical energy.However, the environment could affect the solar panel module andin turn, affect the performance of solar panels or the generatedelectric energy. This research calculated the performance of solarpanels with a single-diode model using the Five Parameters methodthat required solar panel module specification data, the totalradiation absorbed by the solar panel module, and the temperatureof the environment. The Five Parameters method is a methodmodeled after solar panel module performance in the form of thesingle-diode equivalent circuit. The Five Parameters method isreliable in predicting the energy produced by the solar panels whenthe input data is limited. The results for using the Five Parametersin monocrystalline solar panels were Isc = 1.827 A, Imp = 0.662 A,Voc = 18.221 V, Vmp = 15.019 V, Pmp = 9.955 W. And the results inpolycrystalline solar panels were Isc = 1.926 A, Imp = 0.686 A, Voc =17.594 V, Vmp = 14.166 V, Pmp = 9.722 W. Based on the results; itwas concluded that the most efficient and optimised types of solarpanels on natural conditions in Sendang Biru Beach was themonocrystalline solar panel because it produced electrical outputpower of 9.955 W. Therefore, there could be a manufacturer ofsolar energy power plants to reduce the cost of electricity in thecoastal area, such as in Sendang Biru Beach.

The Cole‐Cole model in time domain induced polarization

Geophysics ◽  
1981 ◽  
Vol 46 (6) ◽  
pp. 932-933 ◽  
Author(s):  
T. Lee
Keyword(s):  
Equivalent Circuit ◽  
Time Domain ◽  
Induced Polarization ◽  
Relaxation Model ◽  
Trivial Case ◽  
Alternative Expression ◽  
Transient Voltage ◽  
Transient Voltages ◽  
Cole Model ◽  
The Given

Recently Pelton et al. (1978) used a Cole‐Cole relaxation model to simulate the transient voltages that are observed during an induced‐polarization survey. These authors took the impedance of the equivalent circuit Z(ω) to be [Formula: see text]They then gave the expression for the transient voltage [Formula: see text] as [Formula: see text]In equation (2), [Formula: see text] was misprinted as [Formula: see text]. In these equations, [Formula: see text] and [Formula: see text], [Formula: see text] and τ are constants to be determined for the given model. [Formula: see text] is the height of the step current that will flow in the transmitter. A disadvantage of equation (2) is that it is only slowly convergent for large t/τ. Pelton et al. (1978) used a τ which ranged from [Formula: see text] to [Formula: see text]. The purpose of this note is to provide an alternative expression for [Formula: see text] that is valid only at the later stages but which does not have this disadvantage. The trivial case of c = 1.0 is ignored.

Transmission Line Theories for the Analysis of Electromagnetic Transients in Coil Windings

2013 ◽  
pp. 1-44
Author(s):  
Akihiro Ametani ◽  
Teruo Ohno
Keyword(s):  
Transmission Line ◽  
Propagation Constant ◽  
Characteristic Impedance ◽  
Electromagnetic Transients ◽  
Distributed Parameter ◽  
System A ◽  
Three Phase ◽  
Distributed Parameter Circuit ◽  
Transformer Winding ◽  
Phase Transmission

The chapter contains the basic theory of a distributed-parameter circuit for a single overhead conductor and for a multi-conductor system, which corresponds to a three-phase transmission line and a transformer winding. Starting from a partial differential equation of a single conductor, solutions of a voltage and a current on the conductor are derived as a function of the distance from the sending end. The characteristics of the voltage and the current are explained, and the propagation constant (attenuation and propagation velocity) and the characteristic impedance are described. For a multi-conductor system, a modal theory is introduced, and it is shown that the multi-conductor system is handled as a combination of independent single conductors. Finally, a modeling method of a coil is explained by applying the theories described in the chapter.

scholarly journals PENGARUH PANJANG SALURAN TRANSMISI TERHADAP TEGANGAN LEBIH TRANSIENT YANG DISEBABKAN KARENA PROSES ENERGIZED PADA SALURAN TRANSMISI 500 KV

2015 ◽  
Vol 17 (4) ◽  
Author(s):  
Yuniarto Yuniarto
Keyword(s):  
Transmission Line ◽  
Load Condition ◽  
Line Length ◽  
Electromagnetic Transients ◽  
Dominant Factor ◽  
Switch Closure ◽  
Closure Operation ◽  
High Transmission ◽  
Key Word ◽  
Voltage Transient

Yuniarto, in this paper explain that the utility of high transmission line result in the transient over voltage in transmission-line will also increasingly higher, mainly for lightning and switching surge. Switching surge is a dominant factor to show up much transient over voltage in the transmission-line in the level of 230 kV or higher, if it is compared with lightning surge.  Switching surge is caused by single energized process, the process itself to energize a transmission line in no load condition with energy power through switch closure operation. The research was aiming at observing the influence of transmission-line length to transient over voltage that occurred at the energized process in 500 kV transmission line Ungaran-Pedan, which used EMTP (Electromagnetic Transients Program) to simulate it.  The result of simulation showed that the transient over voltage occurred along the transmission-line which caused the higher voltage increase, providing that the line is also longer. Key word : over voltage,  transient, EMTP

scholarly journals Analysis of the Incidence of Direct Lightning over a HVDC Transmission Line through EFD Model

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 555 ◽  
Author(s):  
Ednardo Rodrigues ◽  
Ricardo Pontes ◽  
João Bandeira ◽  
Victor Aguiar
Keyword(s):  
Finite Elements ◽  
Electric Field ◽  
Power Systems ◽  
Transmission Line ◽  
Lightning Strikes ◽  
Shielding Failure ◽  
Hvdc Transmission ◽  
Hvdc Line ◽  
Four Levels ◽  
Electrogeometric Model

HVDC systems are becoming more common worldwide, specially in Brazil, since the adoption of such system for Itaipu’s hydroelectric complex in the 1980’s. Today, the country has the Xingu-Estreito bipole, with length of 2375 km. This system crosses a region with high lightning incidence, a phenomenon which causes faults in power systems. The most widely used model for the positioning of the arrestor cables over a transmission line is the electrogeometric model. This model, however, does not take into account the different potentials over the structure’s surface, and therefore presents significant inaccuracies when assessing the risk of lightning strikes on structures such as a HVDC line. This work then used the Electric Field Deflection (EFD) model with the aid finite elements. Four levels of lightning are assessed (I, II, III and IV), with current peaks of 3.9, 5.4, 10.1 and 15.7 kA. It was verified that the positive pole tends to attract most of the lightning with shielding failures width (SFW) of 12, 8, 4 and 0 m. It was then proposed to move the arrestor cables horizontally. The study indicates that this horizontal shifting of the cables in 5 and 8 m toward the side with larger chance of direct incidence reduces the shielding failure widths in 50% for peak current of 3.9 kA and almost eliminates the strikes for lightning with peak currents of 5.4, 10.1 and 15.7 kA.

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