Reed Switch Protection Devices with Symmetric Component Filter without Current Transformers

2021 ◽  
Author(s):  
Bibigul Issabekova ◽  
Mirat Tokombaev ◽  
Assemgul Zhantlessova
Keyword(s):  
Reed Switch ◽  
Current Transformers ◽  
Symmetric Component ◽  
Protection Devices

On the Problem of Selecting and Replacing Current Transformers for Relay Protection Devices

2020 ◽  
Vol 63 (6) ◽  
pp. 72-82
Author(s):  
Stanislav Kuzhekov ◽  
◽  
Andrey Degtyarev ◽  
Nikolay Doni ◽  
Aleksey Shurupov ◽  
...  
Keyword(s):  
Power Systems ◽  
High Speed ◽  
Short Circuit ◽  
Relay Protection ◽  
Electric Power Systems ◽  
Current Transformers ◽  
Magnetic Cores ◽  
Protection Devices ◽  
Short Circuits ◽  
The Stability

In connection with cases of incorrect operation of high-speed relay protection devices (RPD) in case of short circuits outside their range, the issue of replacing current transformers (CT) of class P with more ad-vanced current converters is relevant. The article shows that the decision to replace existing class P CTs with CTs with a non-magnetic gap should be made taking into account the probability of saturation of the magnetic cores of the latter in a transient short-circuit mode, as well as an increase in their dimensions compared to class P CTs. The issue of using optoelectronic current converters should be resolved after the latter are put into mass production, taking into account the difficulty of integrating the latter with the RPDs implemented using an Electromechanical base. In many cases, the correct functioning of high-speed RPDs without replacing existing CTs of class P can provide the following measures: the use of algorithms that increase the stability of the oper-ation of high-speed RPDs when the CT is saturated; taking into account in the calculations of the settings the rectangular characteristic of the CT magnetization in transient modes and the permissible deceleration of pro-tections under the condition of the dynamic stability of electric power systems; refusal to use CT connection groups (physical sum of currents, delta and star).

Research of Parameters of Electric Power Systems Affecting Core Saturation of Current Transformers with a Closed Magnetic Circuit in Transitional Short Circuit Modes

2021 ◽  
Vol 64 (1) ◽  
pp. 92-100
Author(s):  
Viliya Ivanova ◽  
◽  
Igor Ivanov ◽  
Keyword(s):  
Power Systems ◽  
Electric Power ◽  
Magnetic Circuit ◽  
Short Circuit ◽  
Relay Protection ◽  
Electric Power Systems ◽  
Current Transformers ◽  
Core Saturation ◽  
Protection Devices ◽  
Closed Magnetic Circuit

The relevance of the study is due to the excess of the permissible errors of current transformers in transient short-circuit modes associated with saturation of the cores of current transformers. The latter leads to improper operation of relay protection devices, which can negatively affect the stability of electric power systems and the efficiency of industrial enterprises with a continuous technological cycle, the power failure of which leads to significant economic damage. The aim of this work is to study the parameters of electric power systems that affect the saturation of the cores of current transformers with a closed magnetic circuit in transient short-circuit modes. The object of research is electromagnetic current transformers of accuracy class 10P in electric power systems. The study was carried out using numerical methods for solving algebraic and differential equations, methods of computer modeling of electromagnetic transient processes and functional programming. As a result, the main parameters influencing the nature and intensity of electromagnetic transients in current transformers during a short circuit are noted; it is shown that in transient short-circuit modes, significant errors in the operation of current transformers associated with core saturation are possible; recommended for assessing the compliance of current transformers of accuracy classes 5P, 10P with the conditions for the correct functioning of relay protection devices in transient short-circuit modes, to calculate the time to saturation of current transformers, taking into account the real parameters of the electric power system at the place where current transformers are installed, in addition to the traditional design checking of current transformers by permissible er-rors for the steady state short circuit.

Analiza algoritama za kompenzaciju zasićenja strujnog transformatora

2020 ◽  
Vol 22 (1-2) ◽  
pp. 112-118
Author(s):  
Nenad Belčević ◽  
◽  
Zoran Stojanović
Keyword(s):  
Relay Protection ◽  
Current Transformer ◽  
Main Function ◽  
Negative Consequences ◽  
Current Transformers ◽  
Secondary Current ◽  
Measuring Devices ◽  
Protection Devices ◽  
Primary Current ◽  
A Current

The main function of current transformers is to adapt the high values of the primary current to values suitable for the operation of relay protection devices, i.e. measuring devices. Under normal conditions, a current transformer transforms the current in a virtually permanent ratio, and practically without a phase shift, so the secondary current is actually a scaled value of the primary current. However, when a fault occurs in the power system, currents reach high values. As a result, the flux in the core of the current transformer can reach values above the knee of the magnetization characteristic, causing saturation of the current transformer. When saturation occurs, the secondary current is no longer a scaled value of the primary current, but is deformed. Deformation of the secondary current may cause malfunctioning of some relay protection devices. The development of digital relay protection has made it possible to perform software saturation compensation by applying certain algorithms, thus eliminating the negative consequences that saturation of the current transformer causes. In this paper, one of the possible approaches for compensation of saturation is analyzed, which is based on the application of an equivalent scheme and magnetization curve of the current transformer. Two typical approaches have been singled out, which have been analyzed and tested in more detail. Testing was performed in the MATLAB/Simulink.

scholarly journals DETERMINING THE TIME BEFORE SATURATION OF CURRENT TRANSFORM ERS WHICH PROVIDES CORRECT FUNCTIONING FAST RELAY PROTECTION DEVICES

2021 ◽  
Vol 1 (1) ◽  
pp. 239-240
Author(s):  
Lyudmila Tinina ◽  
Yuriy Konovalov ◽  
Roman Istratov
Keyword(s):  
Graphical Method ◽  
Relay Protection ◽  
Current Component ◽  
Current Transformers ◽  
Correct Operation ◽  
Saturation Time ◽  
Graphical Visualization ◽  
Protection Devices

A table-graphical method for calculating the saturation time is proposed, which allows to optimize the process of selecting current transformers and relay protection devices connected to them to ensure their correct operation in transient ones, accompanied, among other things, by the occurrence of an aperiodic current component, to minimize errors, relying on table-graphical visualization.

scholarly journals Determination of the magnitude of short-circuit surge current for the construction of relay protection on reed switches and microprocessors

2021 ◽  
Vol 6 (5 (114)) ◽  
Author(s):  
Alexandr Neftissov ◽  
Andrii Biloshchytskyi ◽  
Olzhas Talipov ◽  
Oxana Andreyeva
Keyword(s):  
Magnetic Field ◽  
Short Circuit ◽  
Relay Protection ◽  
Main Element ◽  
Current Transformers ◽  
Transient Mode ◽  
Protection Devices ◽  
Aperiodic Component ◽  
Surge Current

A study of the functioning of reed switches under the influence of a magnetic field created by a current in a conductor in a transient mode with the presence of an aperiodic component has been carried out. A well-known method for determining current using reed switches was implemented. At the same time, it was determined that the originally formulated method did not give the required result within the limits of errors. This is most likely due to the peculiarities of the mechanism of movement of the reed switch contacts. Alternatively, the measurements were taken to take the return currents instead of the pick-up currents and the time between the return times. They are more stable. Simulation is performed, experimental determination of the value of surge current by measuring time is carried out. The main element of the created installation was the power transformer coil with low active and high inductive resistance. As part of the study, the reed switches were placed in a magnetic field with an aperiodic component, as in the transient mode. This study will show the applicability of reed switches for the construction of relay protection devices that will not need current transformers to obtain information about the primary current in the conductor. In the course of the research, it was found that the error in determining the magnitude of current was no more than 10 %. Using microprocessors, it is possible to build relay protection devices with a speed of up to 20 ms. This result makes it possible to build new devices. Since in the well-known developments, it was only said about determining the magnitude of current in a steady state. When building relay protection devices on reed switches, without using current transformers, it will be possible to build backup protections that duplicate not only the devices themselves, but also the primary measuring transformers with other sensitive elements. This will improve the reliability of the power supply.

scholarly journals METHOD FOR CALCULATING THE REFINED CHARACTERISTICS OF CURRENT TRANSFORMERS TO INCREASE THE EFFICIENCY OF RELAY PROTECTION DEVICES

2021 ◽  
Vol 2021 (1) ◽  
pp. 149-155
Author(s):  
Lyudmila Tinina ◽  
Yuriy Konovalov ◽  
Roman Istratov ◽  
Maksim Velichko
Keyword(s):  
Power Supply ◽  
Power Supply System ◽  
Relay Protection ◽  
Supply System ◽  
Current Transformers ◽  
Protection Devices

A method has been developed for selecting the technical characteristics of current transformers and connected relay protection devices that ensure the reliability of the power supply system in accord-ance with modern requirements

Alternate Current Transformers

1896 ◽  
Vol 42 (1084supp) ◽  
pp. 17330-17331
Author(s):  
J. A. Fleming
Keyword(s):  
Alternate Current ◽  
Current Transformers
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