scholarly journals Digital technologies for monitoring and implementation of smart diagnostics of the isolation of power supply systems with isolated neutral in the operating mode

2021 ◽  
Vol 75 (2) ◽  
pp. 109-112
Author(s):  
N.P. Kondrateva ◽  
A.A. Shishov ◽  
R.G. Bolshin ◽  
M.G. Krasnolutskaya
Keyword(s):  
Power Supply ◽  
Power Distribution ◽  
Distribution Systems ◽  
Power Supply System ◽  
Single Phase ◽  
Short Circuit ◽  
Digital Technologies ◽  
Operating Mode ◽  
Supply System ◽  
Ground Faults

Nowadays, 75% of emergencies at power supply facilities are caused by single-phase ground faults. The currently used methods of thermal imaging and ultrasonic testing do not allow accurately identify the cause of accidents in electric power distribution systems. The current search generators, due to their low power, cannot cover the entire section of the diagnosed network. The article suggests the use of digital technologies for the intelligent diagnostics of the insulation of power supply system with insulated neutral in the operating mode, allowing on-line diagnostics of the network and analyzing the data obtained for the early prevention of emergency situations. In order to avoid disconnecting sections and diagnose the system in operating mode, it is proposed to check the system using a currentlimiting capacitor, which will be connected to the live parts of each phase under voltage and accurately determine the location of a single-phase short circuit for any number of feeders. The relevance of these studies is due to the fact that, for example, during two years at one of the manufactures 19 emergencies related to single-phase ground faults were recorded. Four of these cases led to a complete stop of the production. Therefore, the development of digital technologies for the implementation of smart diagnostics of the insulation of an energized power supply system with insulated neutral will be of interest to practitioners, scientists, researchers, graduate students and other specialists seeking to study the latest achievements in smart agribusiness for their subsequent application in the real world.

Transient Responses in Continuous Co-Phase Traction Power Supply System

2014 ◽  
Vol 1006-1007 ◽  
pp. 955-961
Author(s):  
Xing Wang Li ◽  
Ju Rui Yang
Keyword(s):  
Contact Line ◽  
Power Supply ◽  
Power Supply System ◽  
Short Circuit ◽  
Supply System ◽  
Transient Responses ◽  
Traction Substation ◽  
Traction Power Supply System ◽  
Traction Power Supply ◽  
Traction Power

Continuous co-phase traction power supply system is the major change of the traction power supply. It is important to analyze the transient response characteristics of overhead contact line for the traction substation feeder protection. This article introduces the main structure of continuous co-phase traction power supply system and the control strategy of traction substation. Meanwhile, transient responses of overhead contact line in the earth short circuit are studied, including metallic earth short circuit and non-metallic earth short circuit (high resistance ground). In the PSCAD/EMTDC electromagnetic transient simulation environment, the effects on the system and the recovery process are studied which the fault occurred in the output interface of traction substation and occurred in overhead contact line.

scholarly journals Research on Control Strategy of AC-DC-AC Substation Based on Modular Multilevel Converter

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Fei Chang ◽  
Zhongping Yang ◽  
Fei Lin
Keyword(s):  
Power Supply ◽  
Power Supply System ◽  
Single Phase ◽  
Supply System ◽  
Multilevel Converter ◽  
Traction Power Supply System ◽  
Three Phase ◽  
Phase Converter ◽  
Traction Power Supply ◽  
Traction Power

Significant disadvantages in power quality especially the unbalance problem and neutral sections restrict the evolution of conventional traction power supply system. A new traction power supply system based on three-phase to single-phase converter is studied, which can transfer active power from three-phase grid to single-phase catenary. One catenary section could be utilized in the new traction power supply system instead of the multiple split sections in conventional system. Three-phase to single-phase converter is the core equipment of new traction power system. MMC (modular multilevel converter) structure of AC-DC-AC substation is proposed in this paper. To solve the problem of the capacitor voltage balancing in MMC, a parallel sorting algorithm based on field programmable gate array (FPGA) is studied. And the correctness and effectiveness of the algorithm are verified by experiments. In addition, it is inevitable that the AC grid voltage will be unbalanced caused by the fault in the new system. Therefore, this paper focuses on the analysis of the effect of the unbalanced grid voltage on the operating characteristics of the MMC system. Finally, the correctness of the theoretical analysis is verified by simulation.

scholarly journals Methods in Single Phase to Ground Faults on Power Distribution Systems

2019 ◽  
Vol 14 (7) ◽  
pp. 10058-10066
Author(s):  
Dur Muhammad Soomro ◽  
Adnan Hasan Tawafan ◽  
Feryal Ibrahim Jabbar
Keyword(s):  
Power Distribution ◽  
Distribution Systems ◽  
Single Phase ◽  
Power Distribution Systems ◽  
Ground Faults

scholarly journals Choosing the type of equivalent circuit of traction substation when calculating short-circuit currents in 25 kV power supply system

2020 ◽  
Vol 79 (3) ◽  
pp. 139-144
Author(s):  
E. P. Figurnov ◽  
Yu. I. Zharkov ◽  
N. A. Popova
Keyword(s):  
Equivalent Circuit ◽  
Power Supply ◽  
Power Supply System ◽  
Short Circuit ◽  
Supply System ◽  
The Other ◽  
Equivalent Circuits ◽  
Traction Substation ◽  
Traction Network ◽  
Short Circuit Currents

When calculating short circuit currents in the traction network, it is necessary to take into account the input resistance of the traction substation, including the resistance of the transformers of the substation and the resistance of the power supply system. The input resistance during short circuit is determined based on the equivalent circuit of the external power supply system, of which this traction substation is an integral part. Traditionally equivalent circuit of a three-phase system has the form of a star, in which the resulting resistances in each phase are connected in series with a source of phase electromotive force, and these sources have a common point. Another equivalent circuit in the form of a triangle is possible, in which on each side the resulting resistances are connected in series with the source of linear electromotive force. It is important to note that neither one nor the other type of equivalent circuit is determined by the connection scheme of the transformer windings of the traction substation. It is only necessary to take into account the absence of a circuit for zero sequence currents. All elements of the equivalent circuit, as is known, should be brought to uniform basic conditions. If the parameters of these elements are expressed in named units, then the basic values are the effective voltage values of the main stage and the rated power of the power transformer of the traction substation. If the components of one and the other equivalent circuits are reduced to one stage of the operating voltage, for example 27.5 kV, then for the same elements of the power supply system, the resistance values in the equivalent circuit in the form of a triangle are three times larger than in the equivalent circuit in the form of a star. In this case, the input resistances of the traction substation for the one and the other equivalent circuits are absolutely identical. Therefore, in the calculation of short circuit currents of the traction network, you can use any of these equivalent circuits of the power supply system and traction substation. Formulas for calculating the resistances of the elements of the power supply system and electrical installations, given in the standards, manuals and reference books, relate to the equivalent circuit of the short circuit in the form of a star. When using an equivalent circuit in the form of a triangle, these resistances must first be tripled, and then divided by three when calculating the short-circuit currents. The meaninglessness of such an operation is obvious. The equivalent circuit of the traction substation and the external power supply system in the form of a triangle when calculating short circuits in the traction network has no advantages compared to the traditional equivalent circuit in the form of a star. The information on the linear currents on the primary and secondary windings of the traction substation transformer during a short circuit in the traction network is given, which is necessary to select the settings of its relay protection kit.

scholarly journals Accounting power supply schemes for traction substations in the calculation of short circuits in the AC traction network

2019 ◽  
Vol 78 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Yu. I. Zharkov ◽  
N. A. Popova ◽  
E. P. Figurnov
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Power Supply System ◽  
Short Circuit ◽  
Supply System ◽  
Power Sources ◽  
Traction Network ◽  
Traction Substations ◽  
External Power ◽  
External Power Supply

When calculating short-circuit currents in the AC traction network, it is assumed that each of the traction substations receives power from uncoupled external power supply sources with known resistances. In some cases, especially when powering a group of traction substations from a high-voltage power line of a longitudinal power supply, the external power supply system affects not only the magnitude of short-circuit currents, but also their redistribution between adjacent traction substations of the interstation area where this circuit is considered. Such unrecorded redistribution can have a negative effect on short circuit protection. The article considers the equivalent circuit of the traction network, taking into account resistance of the external power supply system. Particular attention is paid to the fact that in replacement circuits of direct and negative sequence value of reduced resistance of one phase of a multiwinding transformer, calculated from the short circuit voltage, does not depend on the connection scheme of its windings. It is noted that in some cases it is difficult to obtain a complete scheme of an external power supply system. Considering that the short circuit in the traction network for the external power supply system is remote, it is proposed taking into account the reference network or traction substations as power sources, from which high-voltage transmission lines power the traction substations. Resistance of the supporting substations as power sources must takes into account connected equivalent power system.Such equivalenting should be carried out by known values of currents or short-circuit powers at the inputs of the reference substation or, if such information is not available, by the rated values of the switched-off currents or powers of the switches of high-voltage line connections.The following power schemes for traction substations are considered: each from its own supporting substation, which is part of an electrically uncoupled external power supply system; from the double-circuit high-voltage line of longitudinal power supply when it is powered from different supporting substations; from the supporting network substation, the traction substation receives power from two lines, and from this the traction substations receive power from two lines in a circle pattern.These three common cases cover all the most common power schemes for traction substations. For each of them formulas are given to determine the resulting equivalent resistance of the external power supply circuit, which should be taken into account in the replacement circuit of the traction network.

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