scholarly journals The influence of changing resistance on the determination accuracy of short circuits in power lines

2021 ◽  
Vol 288 ◽  
pp. 01091
Author(s):  
Serdar Nazarov ◽  
Gurbangulych Kelov ◽  
Berdimyrat Gochyev
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Stable State ◽  
Short Circuit Current ◽  
Scientific Work ◽  
Electric Power System ◽  
Electrical Networks ◽  
Zero Sequence ◽  
Short Circuits ◽  
Maintenance Personnel

In high-voltage electrical networks, the occurrence of short circuits leads to forced interruptions in the power supply of large consumers and disruptions in intersystem communications. More than 65% of all types of occurring short circuits are single-phase short circuits [1]. In a single-phase short circuits (SPSC), a change in the zero sequence resistance (ZSR) especially significantly affects the inaccuracy in detection of damage sites (DDS). When choosing DDS methods, preference is given to remote methods according to the parameters of the emergency conditions (PEC), which are recorded by special instruments or determined from the oscillograms of emergency conditions. The use of modern microprocessor-based relay protection and automation devices (RPA) [26] or emergency event recorders allow viewing the oscillograms of emergency events. In a branched 110 kV network with a complex configuration, the DDS accuracy is influenced by a change in the ZSR. Averaging of specific parameters often leads to erroneous results. The choice of one value from the oscillograms puts the maintenance personnel in difficulty. In the scientific work, the influence of changes in the ZSR on the accuracy of the DDS is considered. The changes in the ZSR are influenced by the position of the on-load voltage regulator (OLTC) switches of transformers with a grounded neutral. In the work, for a more accurate record of the specific parameters of the network, a calculation program has been compiled, which allows making changes in the calculated specific parameters of the network. To determine the short-circuit current from the oscillograms, it is proposed to determine the stable state of accidents in which the current value will be approximately the same. The analysis of the oscillograms of SPSC in 110-220 kV networks in the southern part of the electric power system of Turkmenistan has been carried out.

Investigation of dependences of selectivity of devices of protection against the value of short circuit currents in electrical networks up to 1000 V

2021 ◽  
pp. 98-100
Author(s):  
I. Radko ◽  
◽  
V. Nalivayko ◽  
O. Okushko ◽  
I. Bolbot ◽  
...  
Keyword(s):  
Single Phase ◽  
Modular Design ◽  
Short Circuit ◽  
Electrical Network ◽  
Electrical Networks ◽  
Circuit Breakers ◽  
New Energy ◽  
Short Circuits ◽  
Pole Scheme ◽  
Short Circuit Currents

According to PUE-2017, each group line must be protected against short circuits. Instant disconnection (cut-off) of the line in the event of short circuits provides an electromagnetic release of the circuit breaker. Reliable tripping is possible if the current of a single-phase short circuit is greater than the instantaneous tripping current. Today on the market are widely available circuit breakers with characteristics "B", "C" and "D", which are characterized by different multiplicities of the cut-off current of the electromagnetic release. Some European companies produce circuit breakers with other characteristics, which greatly expands the possibilities protection of electrical equipment. The difficulty in organizing the selectivity of protection is that the circuit breakers of modular design when switching off short circuits are characterized by the same switching time (not more than 0.05 s). The purpose of the research is to find ways to organize the selectivity of protection in electrical networks with voltage up to 1000 V using reliable values of short-circuit currents. In networks with a voltage of up to 1000 V, the current of a single-phase short circuit can be calculated fairly accurately if the exact values of all sections of the electrical network are known. In practice, it is not always possible to obtain reliable data on the numerical characteristics of the 0.4 kV network to which a new energy facility is connected. Therefore, it is proposed to consider part of the network as an active quadrupole, the characteristics of which are obtained by measurements at the point of connection. For further calculations it is necessary to know the voltage at the clamps of the four-pole scheme and the internal impedance. Based on the theory of four-pole scheme, you can get the original data for calculations without calculating the internal parameters of four-poles scheme. Thus, it is proposed to use a hybrid method for estimating the magnitude of probable short-circuit currents in electrical networks up to 1000 V when designing new energy facilities. Credible values of short-circuit currents will allow to organize selective protection of electric networks.

scholarly journals Comparative Analysis of High-Voltage Power Line Models for Determining Short-Circuit Currents in Towers Earthing Systems

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4729
Author(s):  
Rafał Tarko ◽  
Jakub Gajdzica ◽  
Wiesław Nowak ◽  
Waldemar Szpyra
Keyword(s):  
High Voltage ◽  
Current Distribution ◽  
Single Phase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Power Line ◽  
Power Lines ◽  
Distribution Analysis ◽  
Short Circuits ◽  
Short Circuit Currents

The article deals with the problems of single-phase short-circuit current distribution in overhead power lines. Short-circuit disturbances cause many negative phenomena in power networks. Since experimental studies of short-circuits in real networks are practically impossible to perform, these effects can be evaluated only theoretically, based on short-circuit current calculations with the use of appropriate mathematical models. Although short-circuit modeling is considered to be one of the simplest power system calculations, the exact mathematical description of the phenomena occurring at short-circuits is complex. Simplified normative methods are often used for short-circuit current calculations; however, this does not give ground for a thorough analysis of short-circuit current distribution in power lines. The distributions are analyzed using power line models with different degrees of complexity in line with the assumptions made for a given model. The paper presents the problem of current distribution analysis in high-voltage overhead lines for single-phase faults to the tower structures. Simulation studies were conducted on the models developed for the calculation of short-circuit currents in the high-voltage power line earthing. The objective of the analysis was to assess the validity of simplification assumptions followed by practical recommendations on the applicability of the models.

scholarly journals ANALISIS GANGGUAN HUBUNG SINGKAT PADA JARINGAN PEMAKAIAN SENDIRI PLTU BOLOK PT. SMSE (IPP) UNIT 3 DAN 4 MENGGUNAKAN SOFTWARE ETAP 12.6.0

2019 ◽  
pp. 79-88
Author(s):  
Agusthinus S. Sampeallo ◽  
Nursalim Nursalim ◽  
Patrisius J. Fischer
Keyword(s):  
Power Plant ◽  
Circuit Simulation ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electric Power System ◽  
Feed Water ◽  
Steam Power ◽  
Steam Power Plant ◽  
Zero Sequence ◽  
Short Circuit Fault

Bolok Steam Power Plant has its own 6.3 kV usage network to service loads such as Feed Water Pump and Circulating Pump Feed. This self-use network is expected to supply unit loads at the Bolok coal-fired steam power plant without any interference. The presence of disturbances such as short circuit in the electric power system can cause problems such as damage to electrical equipment and the emergence of a power outage. Therefore problems that arise like this require an analytical study to determine the short circuit current that will occur while reducing the consequences that arise. This study aims to determine the largest short circuit fault current with the help of ETAP 12.6.0 software. Short circuit simulation results with ETAP 12.6.0 will be compared with manual calculations based on positive, negative and zero sequence impedance values from the point of disturbance location. Based on the results of the research that has been done, it is known that the type of two-phase short circuit interference to the ground is the largest type of interference, which is equal to 10,615 kA on the generator bus. Whereas for the smallest type of short circuit interference is the type of disturbance one phase to the ground that is equal to 3,967 kA on the OutGoing II bus. From the results of the simulations conducted, it can also be seen that changes in the value of short circuit fault currents are affected by changes in the number of operating loads. The more load that operates the positive and negative sequence impedance the smaller and the value of the short circuit current will be greater, while the zero sequence impedance does not affect the amount of load operating, as well as the opposite.

About the Selection of a Single-Phase Short-Circuit Current on Earth in the Network With Low-Ohm Resistive Grounding of the Neutral

2017 ◽  
pp. 34-41
Author(s):  
Andrei V. MAIOROV ◽  
◽  
Kirill A. OSINTSEV ◽  
Andrei V. SHUNTOV ◽  
◽  
...  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Selection Of

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 Regularities of Control of Mechanized Pulse-Arc Welding Process for Ensuring its Stability

2019 ◽  
pp. 65-76
Author(s):  
S. Yu. Maksymov ◽  
L. S. Shlapak ◽  
А. А. Havryliuk ◽  
І. М. Semianyk ◽  
V. А. Onyskiv
Keyword(s):  
Arc Welding ◽  
Low Voltage ◽  
Short Circuit ◽  
Welding Current ◽  
Short Circuit Current ◽  
Average Frequency ◽  
Maximum Value ◽  
Current Growth ◽  
Short Circuits ◽  
Electrode Metal

Mechanized arc welding in protective gases with short circuits (s.c.) is performed at moderate values of the welding current (up to 180 ... 220 A) and at the relatively low voltage (18 ... 24 V) on the arc. The main disadvantage of the process is spattering when melting an electrode metal and when transferring it to a weld bath. The elimination of disadvantages is possible through the implementation of a controlled transfer of molten electrode metal to a welding bath - due to the pulsed nature of arc burning.  At pulse-arc welding (PAW), one of the main methods of increasing the efficiency of the process is to limit the maximum value of the short-circuit current Imax s.c. by increasing the inductive resistance L in the arc-welding circuit. Proceeding from the features of mechanized arc welding, the purpose of the research is to specify the influence of the velocity of the growth of the welding current vс during the s.c. on the arc stability. The implementation of experimental work presupposes surfacing on a plate with the programming of the operating mode of the inverter at different values (9, 12, 15, 18, 21, 24, 27, 30) with the frequency f = 25 Hz and a pulse ratio C = 2. While analyzing oscillograms of welding current and processing their records, it was established that a decrease of the velocity of the welding current growth leads to a significant limitation of the maximum value of the short-circuit current. The statistical processing of the momentary values of the welding current shows that the increase in the velocity of current growth vс starting with vс = 1.23 kA / s to vс = 50 kA / s makes the average short-circuit duration 10 times shorter. At the same time, the average frequency of short circuits grows more than twice. The increase of vс leads to the destabilization of the pulse process and this is reflected in the 30-times increase of the average frequency of arc break. The increase of the energy indexes of the PAW to the Iav. = 220 ... 225 A, Uav. = 24.5 ... 25.9 V, Q ≈ 7.9 ... 8.0 kJ / cm led to the changes in the parameters which characterize the process of pulsed welding with short circuits. There is a sharp decrease in the average frequency of short circuits (2 ... 3 times as rarely) and the average duration of s.c. (twice shorter).

Review of Short Circuit Current Prediction Technology in Electric Power System

2021 ◽  
pp. 311-327
Author(s):  
Xiren Miao ◽  
Shengbin Zhuang ◽  
Jiamin Li ◽  
Lingling Tang
Keyword(s):  
Power System ◽  
Electric Power ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electric Power System
Sign in / Sign up

Export Citation Format

Share Document