scholarly journals Designing of a distance protection stage based on data on branched line supply end currents

Vestnik IGEU ◽  
2019 ◽  
pp. 44-53 ◽  
Author(s):  
L.M. Kolesov ◽  
V.V. Mozhzhukhina
Keyword(s):  
Low Power ◽  
Transmission Lines ◽  
Low Voltage ◽  
Impedance Measurement ◽  
Distance Protection ◽  
Long Distance ◽  
Backup Protection ◽  
Response Characteristics ◽  
Short Circuits ◽  
Analytical Expressions

At present, in 110–220 kV transmission lines the problem of interphase short-circuits in the long-distance backup protection zone, in most cases, is solved by a backup level of current or distance protection. The existing protection solutions for lines with branching are based on the use of special high-voltage equipment, various current components and their ratios, a virtual resistance relay; on the control of emergency and orthogonal current components with adaptive braking and signal correction as well as with correction of the response characteristics according to the data on the voltage change and the state of the switching devices of the main substation. A number of developments are aimed at increasing the sensitivity of back-up protection of branch substations by changing the connection circuit, improving the response characteristics and refining the method for selecting the settings. However, these protection solutions in many cases do not provide the required sensitivity during short circuits on the low voltage side of a low-power branch transformer. All this means that an urgent problem to be solved is developing an algorithm for the operation of backup protection, providing the required sensitivity to short circuits on the low voltage side of the branch transformer. Analytical methods and simulation in the Simulink and SimPowerSystems packages of the Matlab modeling system were used to determine the impedance measurement of the distance protection measuring element. A mathematical model of the lumped-parameter line was used. When deriving analytical expressions, the impedances of the positive and negative sequences were assumed to be equal. Analytical expressions were obtained for determining the impedance measurement of the proposed and existing distance protection during phase-to-phase short-circuits appearing after a branch transformer and under load conditions. The studies have shown that the proposed distance protection has the required sensitivity to short circuits on the low voltage side of the branch transformer and the necessary detuning from load modes. The characteristics and methods for selecting response parameters of the additional stage of distance protection were determined using information on the currents of the line supply ends. The use of an additional distance protection stage developed by the authors based on the sum of currents of the line supply ends can ensure the required sensitivity to phase-to-phase short circuits on the low voltage side of the branch transformer with a star-delta connection circuit and solve the problem of distant backup protection of low power branch substations. The reliability of the data obtained is confirmed by the correspondence of the results of the analytical research and simulation modeling.

scholarly journals Distance backup protection using supply currents on a line with several branches

Vestnik IGEU ◽  
2019 ◽  
pp. 49-59
Author(s):  
L.M. Kolesov ◽  
V.V. Mozhzhukhina
Keyword(s):  
Transmission Lines ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Total Power ◽  
Distance Protection ◽  
Backup Protection ◽  
Response Characteristics ◽  
Mode Recognition ◽  
Urgent Task ◽  
Short Circuits

The third step of distance protection is used as backup protection against phase-to-phase short circuits on 110–220 kV transmission lines. The main problem when using these protections on a line with several branches is to ensure the effectiveness of distant backup protection in case of phase-to-phase short circuits behind branch transformers of substations. The effective solution to distant backup protection is possible to provide by expanding the information base of protection. Currently, backup protection of lines with branches is being developed with control of currents and their components when using a communication channel, and based on algorithmic models of the facility. In this regard, the urgent task is to develop an algorithm for the distance protection ensuring the required sensibility during short circuits on the lower voltage side of the branch transformers. Analytical methods of determining the impedance measurement and simulation in Simulink and SimPowerSystems of the Matlab modeling system are used. The effectiveness of distant backup protection can be evaluated on the basis of recognition possibility of short circuit modes behind the branch transformers. Analytical expressions have been obtained to determine the impedance measurement during phase-to-phase short-circuits behind a branch transformer and under load conditions. Criteria have been developed to assess the proposed protection possibility to recognize the mode of phase-to-phase short circuits behind the branch transformer. Studies have shown that the main factor determining the possibility of mode recognition is the ratio between the protected transformer power and the total power of the branches loads. The use of several impedance measuring elements with their own response characteristics for branches with transformers of different capacities provides mode recognition for any possible correlation of power of branch substations. The use of the distance protection implementation option developed by the authors allows providing the required sensitivity for short circuits behind branch transformers and to solve the problem of distance backup line protection on a line with several branches. The reliability of the data obtained is confirmed by the correspondence of analytical research and simulation results.

Study on a New Setting Method of Distance Relay with Superconducting Fault Current Limiter Adapt in the Grid

2012 ◽  
Vol 588-589 ◽  
pp. 471-474
Author(s):  
Jun Mei ◽  
Bin Liu ◽  
Jian Yong Zheng ◽  
Lei Yao
Keyword(s):  
Transmission Lines ◽  
Single Phase ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Simulation Software ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Distance Protection ◽  
Superconducting Fault Current Limiter ◽  
Current Limiter

Considerable attention is given towards developing Superconducting fault current limiter (SFCL) due to increasing short circuit levels in transmission lines, which itself imposes further changes on the measured impendence at the relaying point and causes significant impact on the lines’ relay protection, especially on the distance protection as the single-phase grounding fault occurs. In this paper, resistive superconducting fault current limiter connected to the grid is studied as the model to analysis how SFCL affects the grounded short-circuit impedance relay’s setting, then an new setting method of distance protection for the SFCL-equipped line is proposed. Finally, a power system model is built to analysis the theory by PSCAD / EMTDC simulation software. The results show that in the condition of using the impedance relays’ new setting method, impedance measurement error is greatly reduced, SFCL and line distance protection can work in coordination with each other properly.

scholarly journals A Novel Two-step Distance Protection for Flexible HVDC Transmission Lines

2021 ◽  
Vol 256 ◽  
pp. 02017
Author(s):  
Zeya Fang ◽  
Minghao Wen ◽  
Junchao Zheng ◽  
Minghao Wen
Keyword(s):  
Transmission Lines ◽  
Low Frequency ◽  
Lumped Parameter Model ◽  
Distance Protection ◽  
Backup Protection ◽  
Hvdc Transmission ◽  
Protection Method ◽  
Dc Line ◽  
Hvdc Line ◽  
Step Distance

DC line fault is one of the key problems that must be solved in a flexible HVDC system. During quite a long time between the existing main protection and backup protection of the HVDC line, there is no line protection method to detect the fault, which may lead the protection at the AC side to act before the backup protection of the DC line. To solve the problem, a novel two-step distance protection for flexible HVDC lines is proposed in this manuscript. Firstly, based on the uniform distributed parameter model, the equivalent lumped parameter model of the HVDC transmission line at low frequency is analyzed. Secondly, according to the time domain differential equation and the least squares algorithm, novel distance protection based on the iterative calculation of fault distance is proposed, which can eliminate the influence of distributed capacitive current and improve the precision of calculation. To improve the rapidity and reliability of the distance protection, low pass filters with two different cut-off frequencies are used to process the electrical quantities. Finally, simulation results show that the proposed distance protection can respond to metallic poleto-ground faults and pole-to-pole faults rapidly and reliably.

Novel Distance Protection Based on Distributed Parameter Model for Long-Distance Transmission Lines

2013 ◽  
Vol 28 (4) ◽  
pp. 2116-2123 ◽  
Author(s):  
Guobing Song ◽  
Xu Chu ◽  
Shuping Gao ◽  
Xiaoning Kang ◽  
Zaibin Jiao ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Distributed Parameter ◽  
Distance Protection ◽  
Long Distance ◽  
Long Distance Transmission ◽  
Distributed Parameter Model

scholarly journals Application of Estimation of Model Parameters for Protective Automation of Transmission Lines

2020 ◽  
Author(s):  
◽  
Ivars Zālītis
Keyword(s):  
Communication Networks ◽  
Transmission Lines ◽  
Fault Location ◽  
Single Phase ◽  
Model Parameters ◽  
Distance Protection ◽  
Long Distance ◽  
Fault Parameters ◽  
Automatic Reclosing ◽  
Available Information

Transmission lines are indispensable part of power transmission system, which are highly exposed to fault risk factors of environmental and anthropogenic nature. Therefore, protection and control have to be robust and reliable as possible. Distance protection and some of fault location methods, used today for transmission lines, operate within a limited scope of available information that can result in errors and incorrect operation, especially when faults have high transient resistance. In order to overcome these drawbacks of one-terminal-based distance protection and fault locations methods it is proposed to use a technique of estimation of unknown power system model parameters, solving these problems as an optimisation tasks. The scope of available information is extended by incorporation of all measurements, available from the controlled substation, thus eliminating necessity of long-distance communication networks, and by a separate stage of parameter estimation during the pre-fault regime, which is similar to estimation of fault parameters but operates with a nonlinear model reflecting the influence of governors. The Thesis provides modelling tools for both pre-fault and different fault regimes based on symmetrical component and topological modelling methods to accommodate the increased measurement scope. The proposed method was extensively tested considering two different strategies for selection of measured parameters used by the optimisation. The proposed method and its results is not limited to the fault location or distance protection, as the developed technique was also used to create a new method of an adaptive single-phase automatic reclosing algorithm. The proposed method can be used as a base for creation of robust algorithms and devices for the fault location, distance protection and single-phase automatic reclosing. It can also be modified or directly implemented for different transmission line automation and protection problems. The modelling tools described in the Thesis can be used for a further analysis and development of relay protection and automation.

scholarly journals Substation-area Backup Protection Scheme for the Failure of 10kV Line Protection Device

2021 ◽  
Vol 2087 (1) ◽  
pp. 012009
Author(s):  
Yuxue Wang ◽  
Wei Liu ◽  
Shaolin Jiao ◽  
Zeya Fang ◽  
Yiquan Li ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Low Voltage ◽  
Fault Isolation ◽  
Protection Device ◽  
Backup Protection ◽  
Protection Scheme ◽  
Test Information ◽  
Shared Information ◽  
Protection Devices ◽  
Operation Status

Abstract The research on wide-area backup protection for high-voltage transmission lines has made certain progress in recent years, but there are few reports published on substation-area backup protection for low-voltage 10kV transmission lines. Based on the characteristics of shared information in intelligent substation, a substation-area backup protection scheme to deal with the failure of 10kV line protection device is proposed in this paper. This scheme uses the device self-test information and heartbeat mechanism to monitor the operation status of 10kV line protection devices; to realize the substation-area backup protection for the 10kV transmission lines when any line protection device fails, the protection criterion is constructed by the action results of power directional elements of transformer protections and other 10kV line protections. The proposed scheme can greatly improve the speed of the fault isolation and has low requirements for data demand and synchronization. PSCAD simulation results show that the proposed method is with high correctness and feasibility.

scholarly journals Comparative studies of various types of transmission lines in the frequency range 70 GHz 1 THz for ITER ECE diagnostic

2019 ◽  
Vol 203 ◽  
pp. 04009
Author(s):  
Ravinder Kumar ◽  
S. Danani ◽  
H.K.B. Pandya ◽  
P. Vaghashiya ◽  
V.S. Udintsev ◽  
...  
Keyword(s):  
Low Power ◽  
Transmission Lines ◽  
Michelson Interferometer ◽  
Transmission System ◽  
Absorption Lines ◽  
Frequency Range ◽  
Corrugated Waveguide ◽  
Long Distance ◽  
Experimental Conditions ◽  
Cyclotron Radiation

In ITER, an Electron Cyclotron Emission (ECE) diagnostic is planned to measure the electron temperature by measuring the cyclotron radiation in the frequency range of 70-1000 GHz. The cyclotron radiation is usually of low power and needs to be transported with low attenuation over a long distance of ~ 43 m, through a suitable transmission system. Pertaining to long distance, the transmission system will consist of straight waveguide sections, miter bends and waveguide joints. Low power, low loss transmission in a broadband frequency range over long distance makes the design of the transmission system challenging. To arrive at a suitable transmission system, attenuation measurements of three types of transmission lines (TLs) have been performed i.e. circular smooth walled, corrugated and dielectric coated waveguide. A polarizing Michelson interferometer based on Martin-Puplett design has been used to measure the spectrum from waveguide set ups and liquid nitrogen has been used as the black body radiation source. The measured spectrum shows atmospheric water vapour absorption lines in all types of TLs. The preliminary measurement shows that the attenuation of smooth walled waveguide is found to be comparable to corrugated waveguide up to ~ 600GHz and better than corrugated waveguide above 600 GHz for the chosen set of experimental conditions. Further, to avoid water absorption lines, a smooth walled TL is evacuated up to rough vacuum (~10-2mbar) and it was observed that the attenuation is decreased and overall transmission is improved.

Analysis of 6T SRAM Cell in Different Technologies

2017 ◽  
Vol MCSP2017 (01) ◽  
pp. 7-10 ◽  
Author(s):  
Subhashree Rath ◽  
Siba Kumar Panda
Keyword(s):  
Low Power ◽  
Data Storage ◽  
Low Voltage ◽  
Random Access ◽  
Storage Device ◽  
Cmos Process ◽  
Process Technology ◽  
Digital Devices ◽  
Noise Margin ◽  
Sram Cell

Static random access memory (SRAM) is an important component of embedded cache memory of handheld digital devices. SRAM has become major data storage device due to its large storage density and less time to access. Exponential growth of low power digital devices has raised the demand of low voltage low power SRAM. This paper presents design and implementation of 6T SRAM cell in 180 nm, 90 nm and 45 nm standard CMOS process technology. The simulation has been done in Cadence Virtuoso environment. The performance analysis of SRAM cell has been evaluated in terms of delay, power and static noise margin (SNM).

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