scholarly journals Impact of Asymmetry of Over-Head Power Line Parameters on Short-Circuit Currents

2020 ◽  
Vol 5 (4) ◽  
pp. 112-115
Author(s):  
Žaneta Eleschová ◽  
Marián Ivanič
Keyword(s):  
Power System ◽  
Short Circuit ◽  
Power Line ◽  
Ground Fault ◽  
Three Phase ◽  
Calculation Results ◽  
Phase Conductors ◽  
The Impact ◽  
Short Circuit Currents

<span lang="EN-GB">This paper analyses the impact of asymmetry of over-head power line parameters on short circuit currents when three-phase fault and phase-to-ground fault occur. The calculation results with consideration of an asymmetry of the power line parameters are confronted with the calculation in accordance with the Slovak standard STN EN 60909 which does not consider asymmetry of equipment parameters in the power system. The calculation of short-circuit conditions was carried out for two types of 400 kV power line towers on which is a considerably different arrangement of phase conductors.</span>

Short circuits currents comparison of 6 (10) kV and 20 kV.

2020 ◽  
Vol 14 (1) ◽  
pp. 21-26
Author(s):  
S. SKRYPNYK ◽  
◽  
A. SHEINA ◽  
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Transmission Lines ◽  
Power Supply ◽  
Short Circuit ◽  
Electric Arc ◽  
Electrical System ◽  
Three Phase ◽  
Short Circuits ◽  
Short Circuit Currents

Most failures in electrical installations are caused by short circuits (short circuits), which occur as a result of a failure in the electrical strength of the insulation of the conductive parts. A short circuit is an electrical connection of two points of an electric circuit with different values of potential, which is not provided by the design of the device, which interferes with its normal operation. Short circuits may result from a failure of the insulation of the current-carrying elements or the mechanical contact of the non- insulated elements. Also called a short circuit is a condition where the load resistance is less than the internal resistance of the power source. The reasons for such violations are various: aging of insulation, breakages of wires of overhead transmission lines, mechanical damages of isolation of cable lines at ground works, lightning strikes in the transmission line and others. Most often, short-circuits occur through transient resistance, such as through the resistance of an electric arc that occurs at the point of damage to the insulation. Sometimes there are metallic short circuits in which the resistance of the electric arc is very small. The study of short circuits in the power grid is a major step in the design of modern electrical networks. The research is conducted using computer software, first by modeling the system and then simulating errors. A malfunction usually leads to an increase in the current flowing in the lines, and failure to provide reliable protection can result in damage to the power unit. Thus, short-circuit calculations are the primary consideration when designing, upgrading, or expanding a power system. The three-phase short circuit is the least likely. However, in many cases, the three-phase short circuit is associated with the most severe consequences, as it causes the highest power imbalances on the shafts of the generators. The study of transients begins with the mode of three-phase closure due to its relative simplicity in comparison with other types of asymmetry. In most cases, the analysis and calculation of the transient regime of the electrical system involves the preparation of a calculated scheme of substitution, in which the parameters of its elements are determined in named or relative units. The electrical substitution circuitry is used to further study the transients in the power system. The definition of electrical and electromagnetic quantities in relative units is widely used in the theory of electric machines. This is because it significantly simplifies the theoretical calculations and gives the results a generalized view in the practical calculations of currents and residual voltages at the short circuit. By the relative value of any value is understood as its relation to another value of the same name, taken as the base. So, before presenting any quantities in relative units, we need to choose the basic units. In the electrical system with increased voltages, the overall load capacity of the network increases, which in turn makes it possible to supply high-quality electrical energy over a greater distance. In the process of comparing the type of transmission lines, it should be noted that the advantages of the cable transmission line. According to the results of the calculation of short-circuit currents, it can be concluded that in networks with a larger line cross-section and a higher voltage, the short-circuit currents are larger. Thus, during the transition of the electric networks to the higher voltage class of 20 kV, the currents of the KZ increased by 43% compared to the 6 kV electric network. This analysis shows that the importance of reliable power supply in the power supply system for high voltage classes must be high and have equipment to prevent emergencies. In the future, it is planned to develop a systematic calculation of short-circuit currents for a number of transmission lines and to conduct mathematical modeling in the system of applications for the study of transient processes at short circuits.

scholarly journals Three-Phase Fault Analysis on Transmission Line in Matlab Simulink

2021 ◽  
Vol 9 (VI) ◽  
pp. 5386-5391
Author(s):  
Harshal Vilas Patil
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Short Circuit ◽  
Electrical Equipment ◽  
Fault Analysis ◽  
Single Line ◽  
Double Line ◽  
Ground Fault ◽  
Proposed Model ◽  
Three Phase

Now-a-days the demand of electricity or power areincreases day by day this results to transmits more power byIncreasing the transmission line capacity from one place to theother place. But during the transmission some faults areoccurred in the system, such as L-L fault (line to line), 1L-Gfault (single line to ground) and 2L-G fault (double line toground). These faults affect the power system equipmentswhich are connected to it. The main aim of this paper is tostudy or analysis of faults and also identifies the effect of thefault in transmission line along with bus system which isconnected to transmission line. Mainly the major faults in longtransmission lines is (L-G) single line to ground fault which areharmful to the electrical equipment. A proposed model intransmission line is simulated in MATLAB software to analysisand identified the faults. Fault block was taken from the sim-power system block library. The whole modeling andsimulation of different operating and different conditions offault on transmission line, their faults are L-G fault, 2L-Gfault, 3L-G fault and three line short circuit of the proposedwork is presented in this paper.

scholarly journals Analysis of power system operation at asymmetrical load

2018 ◽  
Vol 19 ◽  
pp. 01029
Author(s):  
Stefan Paszek ◽  
Adrian Nocoń ◽  
Piotr Pruski
Keyword(s):  
Power System ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Angular Speed ◽  
Power Line ◽  
Model Parameters ◽  
System Operation ◽  
Two Phase ◽  
The Impact ◽  
Generator Stator

The paper presents a mathematical model of a power system (PS) consisting of a generating unit (with a synchronous generator) connected by a high voltage (transmission) power line to a bus. The state and output equations of the generator are expressed in the coordinate system d, q, 0 and with the use of phase quantities of the generator stator, the bus and the power line, which is especially useful in the analysis of asymmetrical states. A disturbance of the steady state in the form of a two-phase short-circuit in the transmission line was taken into account in the made calculations. The influence of the excitation system and angular speed control system of the generator as well as the impact of selected generator model parameters on the waveforms were investigated.

Neural network based calculation of short-circuit currents in three-phase systems

1992 ◽  
Vol 24 (1) ◽  
pp. 49-53 ◽  
Author(s):  
Miodrag Djukanovic ◽  
Dusko Bekut ◽  
Dejan J. Sobajic ◽  
Y.H. Pao
Keyword(s):  
Neural Network ◽  
Short Circuit ◽  
Three Phase ◽  
Phase Systems ◽  
Short Circuit Currents

Calculation and Analysis of Three-Phase Transformer Short-Circuit Current

2014 ◽  
Vol 986-987 ◽  
pp. 1914-1917
Author(s):  
Pei Ming Pan ◽  
Huan Lian ◽  
Fei Xiang Hui ◽  
Wei Pu Tan
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Stable Operation ◽  
Application Range ◽  
Three Phase ◽  
Different Types ◽  
Calculation Results ◽  
Current Calculation ◽  
Important Significance ◽  
Selection Of

Analysis the important significance of transformer short-circuit current calculation for the stable operation of power system. Lead to three different types of transformer short-circuit current calculation methods, this literature uses a simplified example to compare the characters among three methods. Meanwhile, calculation by using the theory to get a quantitative range of simplified method. The calculation results and theory support each other, finally, summarizing the application range of the three methods, and offering a reference for reasonable selection of short-circuit current methods.

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