scholarly journals DETERMINING A TYPE OF A DAMAGE IN THE CURRENT PROTECTION OF POWER LINES OF 6–35 KV

2017 ◽  
Vol 60 (6) ◽  
pp. 497-504 ◽  
Author(s):  
F. A. Romaniuk ◽  
E. V. Buloichik ◽  
O. A. Huryanchyk ◽  
M. A. Shevaldin
Keyword(s):  
Dynamic Properties ◽  
Short Circuit ◽  
Distribution Networks ◽  
Two Phase ◽  
Worst Case ◽  
Reliable Determination ◽  
Three Phase ◽  
Short Circuits ◽  
Current Unbalance

The methods to identify types of phase-to-phase short circuits that can be used to improve technical excellence by speed-current line protection of distribution networks of 6–35 kV are considered. As a result of the assessment of the appropriateness of their application in current protection, the choice was made in favor of the method based on the control of the relative current unbalance. The influence of contact resistances and load currents of various levels on the magnitude and character of the change of relative unbalance taking into account the errors of measuring transformers of current has been studied with the aid of the method of numerical experiment. It is demonstrated that in a lot of cases of arch short circuits in the loaded power line and in idle mode, the control only asymmetry is insufficient for reliable determination of the type of damage. A better algorithm has been proposed for determining phase-to-phase short circuit based on the control and the analysis of the two relative unbalance currents determined by the current values of the differences of the phase currents of the line. Its serviceability was evaluated. It was found out that in all the modes being considered, the proposed method – when boundary conditions are properly chosen – makes it possible to fix three-phase and two-phase short circuit on the protected line, and in the area of remote redundancy. The dynamic properties of the proposed method are investigated for different modes of the line. It is established that in the worst case, the determining of the damage is provided during the time not exceeding 25 ms.

scholarly journals Determination of the Fault Zone by the Level of Short-Circuit Currents

2018 ◽  
Vol 61 (5) ◽  
pp. 396-407
Author(s):  
F. A. Romaniuk ◽  
E. V. Buloichyk ◽  
M. A. Shevaldin
Keyword(s):  
Fault Zone ◽  
High Speed ◽  
Computational Experiment ◽  
Fault Location ◽  
Dynamic Properties ◽  
Short Circuit ◽  
Worst Case ◽  
Reliable Determination ◽  
Calculated Distance

The methods of determination the fault zone according to the parameters of the emergency mode, which can be used to improve the performance of technical perfection of current protection lines of distributive 6–10 kV one-way power networks, are considered. The advantage of the algorithm of determination the zones of short circuit (SC) according to the level of emergency currents as compared to the remote unilateral method addressing the parameters of the damaged loop corrupted loops (loops) is noted. Calculation of the estimated distance to the point of SC on the basis of difference of damaged phase currents has been proposed, that enables the independence of the obtained result on the type of the fault. A technique for increasing the reliability of the method for determination the short-circuit zone by the level of emergency currents based on information about the type of damage has also been proposed. The effect of load currents and contact resistances of different levels on the magnitude and nature of the changes in the errors of the calculated distance to the short circuit was investigated by the method of computational experiment. The levels of contact resistances relative to the total resistance of the line depending on the place of SC occurrence are determined that provides reliable determination of the fault zone; it is demonstrated that the nature of their alteration is approximately the same for lines of medium and long length. The expediency of correction of the calculated distance to the fault location in many cases of short circuits through the contact resistance so to improve the protection capacity of the high-speed current protection stage is demonstrated. Based on the results of the computational experiment, correction factors for the correction of the value of the emergency current have been obtained; on the basis of the latter the fault zone is determined. The estimation of efficiency of the proposed method of correction has been carried out; it is shown that its application makes it possible to improve the accuracy of determination the fault zone and to expand the zone of instantaneous shutdown of short circuit. The dynamic properties of the proposed algorithm for different modes of the line operation have been investigated; it is ascertained that, in the worst case, the determination of the short circuit zone for a time not exceeding 27 ms is provided.

Some aspects of the calculation of short circuits in mine distribution networks. The calculation of the effective values of the short-circuit currents is carried out in order to determine the minimum

2020 ◽  
Vol 14 (1) ◽  
pp. 66-69
Author(s):  
V. KALINICHENKO ◽  
◽  
I. PRIDATKO ◽  
Keyword(s):  
Short Circuit ◽  
Distribution Networks ◽  
Two Phase ◽  
Cable Network ◽  
Transformer Substation ◽  
Three Phase ◽  
Short Circuits ◽  
Artificial Introduction ◽  
Short Circuit Currents ◽  
Circuit Power

The calculation of the effective values of the short-circuit currents is carried out in order to determine the minimum value of the current of the two- phase short-circuit required to select the settings of the means of protection, as well as the maximum value of the current of the three-phase short-circuit required to test the switching equipment for the ability to switch off. In most studies, the calculation of short-circuit currents is carried out only taking into account the total resistance of the transformer substation and the cable network. They also take into account the maximum short-circuit power (100MVA) due to the use of high-voltage explosion-proof switchgear type KRUV-6 without taking into account the influence of the external network. An external network, in turn, may limit the short-circuit power below 100MVA. The calculation of the short-circuit power of the external system with regard to the network parameters was considered. The actual magnitude of this capacity differs from that accepted in the known calculations and is below these values due to the natural or artificial introduction of reactor reactance and causes an error of 10-40%. Remote short-circuits of the distribution network reduce the short-circuit power of the input terminals of the step-down transformers, and therefore the influence of the external network on the short-circuit currents in the district networks increases. This approach will allow the determination of short-circuit currents in the mine distribution networks with higher accuracy. This will reduce the risk of accidents in an explosive mining environment.

scholarly journals THE RELIABILITY OF DETERMINING THE SHORT CIRCUIT ZONE OF THE LINES OF 6–35 kV

2018 ◽  
Vol 61 (1) ◽  
pp. 5-14 ◽  
Author(s):  
F. А. Romaniuk ◽  
E. V. Buloichyk ◽  
O. A. Huryanchyk ◽  
V. S. Kachenya
Keyword(s):  
Fault Zone ◽  
Fault Location ◽  
Dynamic Properties ◽  
Short Circuit ◽  
Correction Method ◽  
Worst Case ◽  
Factors Affecting ◽  
Definition Of ◽  
Major Factors

A method of increasing the reliability of determining the zone of short-circuit at the current step protection of the lines of 6–35 kV with unilateral power, aimed at improvement of their technical perfection, is presented in the paper. Having taken the relative simpleness of the current protection into account the authors consider the unilateral remote method of accounting the parameters of the emergency mode and the type of fault to be the most suitable for the implementation of the algorithm of its functioning as compared with the existing methods of fault location. The major factors affecting the accuracy of determining the short circuit zone based on the remote method are noted. With the use of the method of computational experiment the influence of the load currents and contact resistances of various levels on the magnitude and character of changes of errors of determination of the calculated distance of the point of fault from the protection installation location taking into account the errors of measuring transformers. It is demonstrated that in many cases of arc short circuit in a loaded line in order to define the zone of short-circuit with fair accuracy correction of the estimated distance to the fault as calculated by the parameters of the damaged loop (loops) is required. According to the results of numerical experiments corrective expressions on the basis of two relative asymmetry currents determined by the current values of the differences of the phase currents of the line for detecting a type of a short circuit have been obtained. The assessment of the efficiency of the proposed method has been performed. It is shown that the application of the proposed correction method makes it possible to increase the accuracy of fault zone detection. The dynamic properties of the proposed method applied to different modes of the line functioning have been studied. It is determined that in the worst case the definition of the fault zone for a maximum duration of 26 μsec is provided.

scholarly journals Complex Electronic Protection for Low-voltage Three-phase Induction Motors

2020 ◽  
Vol 11 ◽  
pp. 11-17
Author(s):  
Gabriel Nicolae Popa ◽  
Corina Maria Diniș
Keyword(s):  
Induction Motors ◽  
Low Voltage ◽  
Short Circuit ◽  
Electronic Devices ◽  
General Purpose ◽  
Two Phase ◽  
Dc Voltage ◽  
Electric Drives ◽  
Normal Limits ◽  
Three Phase

Low-voltage three-phase induction motors are most often used in industrial electric drives. Electric motors must be protected by electric and/or electronic devices against: short-circuit, overloads, asymmetrical currents, two-phase voltage operation, under-voltage, and over-temperature. To design the electronic protection currents, voltages and temperature must be measured to determine whether they fall within normal limits. The electronic protection was design into low capacity PLC. The paper presents the designs and analysis of complex electronic protection for general purpose low-voltage three-phase induction motors. The electronic protection has Hall transducers and conversion electronic devices for AC currents to DC voltages, AC voltages to DC voltage, temperature to DC voltage, a low capacity PLC, switches, motor’s power contactors, and signalling lamps has been developed. Experiments with complex electronic protection, for different faults are presented. The proposed protection has the advantages of incorporating all usual protections future for the low-voltage three-phase induction motors.

ENGINEERING ANALYSIS OF THE THREE-PHASE SHORT CIRCUIT MODE IN THE 10 KV ELECTRIC NETWORK TAKING INTO ACCOUNT THE INFLUENCE OF LOAD CURRENTS

2021 ◽  
pp. 74-83
Author(s):  
YURI D. VOLCHKOV ◽  
Keyword(s):  
Remote Monitoring ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Load Current ◽  
Electric Network ◽  
Operating Modes ◽  
Three Phase ◽  
Feed Network ◽  
Short Circuits ◽  
Switching Devices

Abstract. The load current aff ects the value of the short-circuit current in the electric network and, consequently, the voltage value. In some cases, this infl uence must be taken into account for the correct choice of switching devices, remote monitoring the operating modes of electric networks, and determining the modes. It is possible to disconnect loads connected through magnetic starters and contactors. Failure to consider the infl uence of the load current can lead to an incorrect interpretation of the identifi ed grid operating modes during remote monitoring and, as a result, incorrect dispatcher’s decisions. In addition, it is also insuffi cient to specify the choice of switching devices in the 10 kV feed network. The article describes a method for analyzing the three-phase short circuit mode in a 10 kV feed network, taking into account the infl uence of load currents. The method is exemplifi ed by the case of an actual electric network – the 10 kV ring feed network containing reclosers and receiving power from diff erent sections of lowvoltage buses of the “Kulikovskaya” 110/35/10 kV substation, belonging to the Branch of PJSC «DGC of Center”-“Orelenergo.” For this network, the values of the three-phase short-circuit currents at points with diff erent distances from the substation buses have been determined. The authors have fi guredout the values of the load currents and their shares in the total short-circuit current. The voltage values at different points of the network in the case of short circuits have also been determined. The research proves that the effect of the load current on the total short-circuit current should be taken into account for the case of remote short circuits.

scholarly journals Alternative Methodology to Calculate the Directional Characteristic Settings of Directional Overcurrent Relays in Transmission and Distribution Networks

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3779 ◽  
Author(s):  
Jaramillo Serna ◽  
López-Lezama
Keyword(s):  
Optimization Problem ◽  
Operating Characteristic ◽  
Short Circuit ◽  
Distribution Networks ◽  
Directional Characteristic ◽  
Overcurrent Relays ◽  
Alternative Methodology ◽  
Transmission And Distribution

When addressing the problem of calculating the settings for directional overcurrent elements, the focus is usually the determination of the pickup, time dial and operating characteristic, in order to ensure proper selectivity with adjacent protection elements, thus limiting the problem related to the settings calculation of the direction determination characteristic to the application of typical settings and general guidelines, which cannot provide a reliable measure of the suitability of such settings. The present article describes in detail an alternative methodology for determining these settings, based on a characterization of the power system where the directional protection is to be applied, through the performance of a detailed short-circuit sensitivity analysis. From this, an optimization problem is formulated and solved to obtain the main settings shaping the direction determination characteristic, and then, a series of variables are used to measure the performance of the obtained settings, and even to improve it. The obtained results show the advantages of the application of the proposed methodology over the traditional methodology, based on typical settings and general guidelines, pointing out the risks of using the later.

scholarly journals Identification of Inter-Turn Short-Circuits in Induction Motor Stator Winding Using Simulated Annealing

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 117
Author(s):  
Marcin Tomczyk ◽  
Ryszard Mielnik ◽  
Anna Plichta ◽  
Iwona Goldasz ◽  
Maciej Sułowicz
Keyword(s):  
Simulated Annealing ◽  
Induction Motor ◽  
Induction Motors ◽  
Early Stage ◽  
Dynamic Properties ◽  
Short Circuit ◽  
State Variables ◽  
Novel Approach ◽  
Short Circuits ◽  
Identification Processes

This paper presents a method of inter-turn short-circuit identification in induction motors during load current variations based on a hybrid analytic approach that combines the genetic algorithm and simulated annealing. With this approach, the essence of the method relies on determining the reference matrices and calculating the distance between the reference matric values and the test matrix. As a whole, it is a novel approach to the process of identifying faults in induction motors. Moreover, applying a discrete optimization algorithm to search for alternative solutions makes it possible to obtain the true minimal values of the matrices in the identification process. The effectiveness of the applied method in the monitoring and identification processes of the inter-turn short-circuit in the early stage of its creation was confirmed in tests carried out for several significant state variables describing physical magnitudes of the selected induction motor model. The need for identification of a particular fault is related to a gradual increase in its magnitude in the process of the induction motor’s exploitation. The occurrence of short-circuits complicates the dynamic properties of the measured diagnostic signals of the system to a great extent.

scholarly journals Analisis Koordinasi Over Current Relay Dan Ground Fault Relay Terhadap Keandalan Sistem

2020 ◽  
Vol 3 (1) ◽  
pp. 30-40
Author(s):  
I Nengah Sunaya ◽  
I Gede Suputra Widharma
Keyword(s):  
Distribution System ◽  
Short Circuit ◽  
Work Time ◽  
Two Phase ◽  
Electricity System ◽  
Ground Fault ◽  
Three Phase ◽  
Overcurrent Relay ◽  
Time Relay

This research had done base on case study in the feeder of substation 20 kV Jababeka. Existing data showed that condition is well with not too long differential, over all setting on the Overcurrent Relay (OCR) – Ground Fault Relay (GFR) in the field is well. From calculated result can be seem that current of short circuit disturb is influenced by distance between disturbance points. Using over current relay has important purpose in the protection of electricity system. The qualification need setting minimum time of over current relay in the feeder not less than 0.3 second. This consider to the relay will not in trip condition in rush current from distribution transformator that has been connected in the distribution system when the feeder starts operated. Starting time for relay in the feeder is faster than work time in the incoming side with average time about 0.4 second for one phase disturbance side. But for three phase and two phase disturbance side, work time relay has interval time about 0.4 second and than increase with average increament about 0.1 second when transmission line is longer (from distance aspects about 0%, 25%, 50%, 75% and 100%).

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.

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