A Single-Ended Transient Based Voltage Protection Method of UHVDC Transmission Line which Distinguishes the Opposite Side’s Internal and External Fault with Protectors

2013 ◽  
Vol 291-294 ◽  
pp. 2244-2249
Author(s):  
Shi Long Chen ◽  
Jie Zhang ◽  
Jia Wei Xie ◽  
Li Liu
Keyword(s):  
Transmission Line ◽  
High Frequency ◽  
Simulation Experiment ◽  
Frequency Characteristics ◽  
Transient Signal ◽  
Protection Method ◽  
Frequency Components

The paper studied the frequency characteristics of UHVDC transmission line and UHVDC transmission line boundary and their attenuation to high frequency components of fault-generated transient signal. The paper points out that existing approaches which utilize protectors to distinguish local side’s internal or external fault can’t protect the whole line. UHVDC transmission line and UHVDC transmission line boundary’s attenuation to high frequency fault-generated transient signal is overall considered, and a single-ended transient based voltage protection method which distinguishes the opposite side’s internal and external fault is proposed. The Yunnan-Guangdong UHVDC model of actual parameters was built up by PSCAD, and simulation experiment was conducted.

scholarly journals High frequency characteristics of a magnetically insulated transmission line oscillator oscillating in HEM11 mode

2008 ◽  
Vol 57 (8) ◽  
pp. 4875
Author(s):  
Wang Dong ◽  
Chen Dai-Bing ◽  
Fan Zhi-Kai ◽  
Deng Jing-Kang
Keyword(s):  
Transmission Line ◽  
High Frequency ◽  
Frequency Characteristics

Research on High Bandwidth Rogowski Coil for Measuring Lightning Traveling Wave Current on Double Circuit Transmission Line

2014 ◽  
Vol 986-987 ◽  
pp. 1558-1564
Author(s):  
Cheng Ju Yang ◽  
Cheng Wei Zhang ◽  
Geng Bin Zhang ◽  
Pei Ling Chen ◽  
Shi Jun Xie
Keyword(s):  
Transmission Line ◽  
Traveling Wave ◽  
High Frequency ◽  
Power Grid ◽  
Low Frequency ◽  
Rogowski Coil ◽  
The Self ◽  
Equivalent Model ◽  
High Bandwidth ◽  
Frequency Components

Double circuit transmission line is an important part of the power grid, which is vulnerable to lightning and may endanger the security and stability of the power grid. In order to design a sensor which can monitor the lightning traveling wave current on double circuit transmission line, simulations of lightning on the double circuit transmission line were conducted. The simulation result shows that besides high frequency components, the traveling wave contains a lot of low frequency components. Based on the equivalent model and the frequency response of the self-integrated Rogowski coil, it turns out that the widely used self-integrated Rogowski coil is not suitable for this application as the problem of low frequency distortion. In this paper, through theoretical analysis and simulations in Matlab, an improved Rogowski coil with analog integrator is proposed which can correct the low frequency distortion of the self-integrated Rogowski coil. All the simulations, experiments and operating data installed to a double circuit transmission line in China verify the validity of the high bandwidth Rogowski coil.

scholarly journals Deformation Forecasting of Surrounding Rock Mass Based on Correlation between Frequency and Fracture Scale of Microseismicity

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Peiwei Xiao ◽  
Bo Qian ◽  
Peng Jiang ◽  
Nuwen Xu ◽  
Biao Li
Keyword(s):  
Rock Mass ◽  
High Frequency ◽  
Surrounding Rock ◽  
Frequency Characteristics ◽  
Deformation And Failure ◽  
Macroscopic Deformation ◽  
Frequency Components ◽  
Microseismic Events ◽  
Statistical Sample ◽  
Fracture Scale

The macroscopic deformation and failure of engineering rock mass may occur as a result of evolution and breakdown of its internal microfracture. Therefore, the macroscopic state of rock mass can be obtained from fracture scale of microfracture in real time. To assess instability and predict macroscopic deformation and failure of engineering rock mass, a time-frequency analysis technique based on S transform was proposed to investigate microseismic waveform and reveal the correlation between macroscopic deformation failure and microseismic frequency characteristics of engineering rock mass in combination with fracture scale. To minimize the influence of external factors on parameters calculated, a significant amount of microseismic data from three large-scale hydropower projects in southwestern China was collected as the statistical sample. The analysis of correlation between fracture scale and frequency characteristics of microseismic events was carried out based on the statistical sample. Combining with microseismic data and multipoint extensometers in the underground powerhouse of the Houziyan hydropower station, engineering verification was conducted. The result shows that the high-frequency components decrease and microseismic signals display low-frequency characteristic as the fracture scale increases; the microseismic high-frequency components decreased at first and then increased during the deformation process of surrounding rock mass, and the frequency of microseismic events shifts from high band to a lower one before deformation.

scholarly journals A Feeder Protection Scheme for DC Micro-Energy System

2021 ◽  
Vol 9 ◽  
Author(s):  
Haitao Song ◽  
Li Yang ◽  
Shaoyu Chen ◽  
Wentao Huang ◽  
Nengling Tai
Keyword(s):  
High Frequency ◽  
Amplitude Ratio ◽  
Energy System ◽  
Safe Operation ◽  
Fast Detection ◽  
Protection Scheme ◽  
Protection Method ◽  
High Penetration ◽  
Frequency Components ◽  
Flexible Operation

DC micro-energy system is an effective pattern to integrate high-penetration distribution generators. It has flexible operation modes and complicated fault characteristics, which requires protection with higher selectivity and sensitivity. This paper proposes a DC feeder protection method using the transient high-frequency currents. The fault direction and fault feeder are identified by comparing the amplitude of high-frequency currents of all ends. The amplitude ratio coefficient of DC voltages is introduced to detect the fault pole. The transient high-frequency components will not be affected by the communication delay and fault impedance. The protection scheme realizes the fast detection and clearance of different faults on feeders before the failure of the inverter-interfaced generators and loads, which ensure the reliable and safe operation of the non-fault zone. The model of a DC micro-energy system is established in MATLAB/Simulink and the efficiency of this method is verified by detailed simulations.

scholarly journals A Novel Approach for Transmission Line Protection Using Wavelet Transform and Neural Network

2011 ◽  
pp. 121-126
Author(s):  
Mrunalini M. Rao ◽  
P.M. Deoghare
Keyword(s):  
Neural Network ◽  
Wavelet Transform ◽  
Transmission Line ◽  
High Frequency ◽  
Low Frequency ◽  
Line Length ◽  
Frequency Information ◽  
Protection Scheme ◽  
Frequency Components ◽  
Transmission Line Protection

The two most important expected objectives of the transmission line protection are – 1) Differentiating the internal faults from external faults and 2) identifying exactly the fault type using one end data only. In conventional distance protection scheme only 80 percent of line length gets primary protection while for remaining 20 percent of line length a time delay is provided to avoid maloperation due to overreach in case of D.C. offset. In this new scheme a fault generated transients based protection method is introduced by which the whole line length gets primary protection by using the concept of bus capacitance. This scheme implements improved solution based on wavelet transform and self-organized neural network. The measured current and voltage signals are preprocessed first and then decomposed using wavelet multiresolution analysis to obtain the high frequency and low frequency information. The training patterns are formed based on high frequency signal components and the low frequency components of all three phase voltages and current. Zero sequence voltage and current are also used to identify faults involving grounds. The input sets formed based on the high frequency components are arranged as inputs of neural network-1, whose task is to indicate whether the fault is internal or external. The input sets formed based on the low frequency components are arranged as inputs of neural network- 2, whose task is indicate the type of fault. The new method uses both low and high frequency information of the fault signal to achieve an advanced transmission line protection scheme.

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