Traveling Wave Method Research Articles

A novel single-ended fault location method for long-distance HVDC transmission lines based on cross-correlation analysis

The transmission line, as the faultiest device in power system, cross many complex areas which will cause worse work condition. This is, both the rate of faulty and the difficulty of the manual fault location are raised. While accurate fault location method could reduce the workload and outage cost, increase the speed of repairing and improve both the reliability and economics of power system. Therefore, it is essential for HVDC systems which have much longer transmission lines. The existing fault location device of HVDC transmission lines are based on the principle of transient travelling-wave. However, due to the interference caused by on-off of power electronic devices and signal resonances, the single-ended travelling-wave method can not be applied in HVDC. The characteristics of clutter interferences of HVDC system and the coupling between double pole lines are analyzed in paper. A novel single-ended travelling-wave fault location method for HVDC transmission lines based on the correlation between two pole lines is proposed. The signal of the non-fault pole line is applied as reference signal; the method suppresses interference through the cross-correlation calculation between the fault and the no-fault pole line. So the reflected wave is enhanced and the identification reliability of the reflected wave is improved. The validity of the method is verified by simulation and on-site data analysis.

Lightning Protection of ± 500 kV Three-circuit Direct Current Overhead Transmission Lines on the Same Tower

The three-circuit flexible DC transmission line in the same tower has great advantages in saving transmission corridors, but its lightning protection design is obviously different from single-circuit or double-return overhead lines. Especially in the case of forming a DC grid, the striking flashover rate should be strictly controlled. For this reason, the lightning withstand performance of ±500kV three-circuit flexible DC transmission lines arranged on the same tower is analyzed by using electrical geometric model and traveling wave method. With such method and model the effect of polar line arrangement, grounding resistance, tower height on the lightning protection are analyzed. The computational results prove that when the lightning protection angle of overhead ground wire is designed to be -14° and the recommended E layout scheme is adopted for the pole conductor, the striking flashover rate can be controlled to be less than 0.1 times/(100km·a). The research results lay the foundation for the lightning protection design of the ±500kV three-circuit flexible DC lines arranged on the same tower.

Protection of High-Voltage DC Grids Using Traveling-Wave Frequency Characteristics

Fast dc fault detection in high-voltage dc (HVdc) grids is paramount due to the possibility of attaining a severely high fault current within few milliseconds. This article proposes a new traveling-wave (TW) based protection scheme to detect and locate faults in HVdc grids. In contrast to the existing TW-based protection and fault location approaches, the proposed scheme, first, utilizes only the first locally measured TW after the inception of a fault, and, second, focuses on the frequency content and polarity of the TW, rather than its arrival time. The direction of the TW is identified based on the pattern of the current TW waveform. A frequency spectral ratio of the current TW is proposed to identify the fault zone and fault location with high accuracy. The proposed method ensures a detection speed of 50 $\mu$ s on overhead lines and 500 $\mu$ s on underground cables. A remote backup scheme is coordinated with the primary protection and operates within 1.05 ms, which meets the speed requirement of HVdc grids. The performance of the proposed scheme has been, first, assessed using the CIGRE B4 HVdc test grid under various conditions, and, second, compared to existing single- and two-terminal TW methods.

Transmission line fault location: Simulation of real faults using wavelet transform based travelling wave methods

In this study, High Voltage Transmission Line fault location accuracy of distance relays running impedance algorithm are compared with Travelling Wave (TW) method. Line faults in 154 kV Tatvan – Muş and 154 kV Patnos-Erciş lines in Turkish Electrical Transmission System are analyzed. Real faults in both lines are simulated in MATLAB-SIMULINK. Tower configuration and conductor properties of the lines and the source impedances are included in the simulation to comply with real system. Simulations show that both single-end and double-end Wavelet Transform (WT) based TW methods have better accuracy then the distance relays computing fault location by impedance methods.

Hybrid Pattern Recognition and Multi-resolution Analysis (MRA) Based Fault Location in Power Transmission Lines

This paper proposes a fault (line-to-line) location on Ikeja West – Benin 330kV electric power transmission lines using wavelet multi-resolution analysis and neural networks pattern recognition abilities. Three-phase line-to-line current and voltage waveforms measured during the occurrence of a fault in the power transmission-line were pre-processed first and then decomposed using wavelet multi-resolution analysis to obtain the high-frequency details and low-frequency approximations. The patterns formed based on high-frequency signal components were arranged as inputs of the neural network, whose task is to indicate the occurrence of a fault on the lines. The patterns formed using low-frequency approximations were arranged as inputs of the second neural network, whose task is to indicate the exact fault type. The new method uses both low and high-frequency information of the fault signal to achieve an exact location of the fault. The neural network was trained to recognize patterns, classify data and forecast future events. Feed forward networks have been employed along with back propagation algorithm for each of the three phases in the Fault location process. An analysis of the learning and generalization characteristics of elements in power system was carried using Neural Network toolbox in MATLAB/SIMULINK environment. Simulation results obtained demonstrate that neural network pattern recognition and wavelet multi-resolution analysis approach are efficient in identifying and locating faults on transmission lines as the average percentage error in fault location was just 0.1386%. This showed that satisfactory performance was achieved especially when compared to the conventional methods such as impedance and travelling wave methods.

On the Spatial Resolution of Fault-Location Techniques Based on Full-Fault Transients

This article discusses the mechanisms enabling spatial resolution in fault location methods based on full transient signals, as opposed to those only using their early-time portion. This idea is found in recent travelling-wave methods (TWM) and those based on electromagnetic time reversal (EMTR). Their spatial resolution is discussed in terms of the sensitivity of a system resonances to change in the fault position and their coherence bandwidth. It is proven that using the entire transient signal it is possible to bypass the Fourier transform uncertainty principle, which limits the spatial resolution of time-domain reflectometry and standard early-time TWM. Super-resolved fault location is shown to be possible only for resonating systems, enabling high spatial resolution without relying on wide-band data. A detailed theoretical analysis for laterals and numerical results for networks and a three-phase line show that significant differences can be observed for the spatial resolution associated to each resonance, most often resulting in a loss of spatial resolution. The interaction between separate resonant structures, such as laterals in networks and coupled conductors in three-phase lines are shown to be the main cause of resolution loss.

MT–HVdc Systems Fault Classification and Location Methods Based on Traveling and Non-Traveling Waves—A Comprehensive Review

Estimation of fault classification and location in a multi-terminal high voltage direct current (MT–HVdc) transmission system is a challenging problem and is considered to be a fundamental maneuver of dc grid protection. This research paper critically reviews traveling and non-travelling wave methods of classification and location of dc faults in multi-terminal HVdc transmission systems. Detailed mathematical analysis of MT–HVdc systems composed of high grounding resistance, cable and overhead line segments, and bipolar coupled transmission network under healthy and faulty conditions, are evaluated. The gravity of this research paper addresses benefits and shortcomings of traveling and non-traveling wave methods and futuristic techniques of fault classification and location.

Fault Location Algorithm for HVDC Transmission Based on Synchronized Fault Time

To determine the fault location of the dc line fault in an HVDC transmission system, a new algorithm based on the traveling wave method and learning based method is proposed in this paper. The relationship between the traveling wave time of arrival differences with fault location is presented. The differences in traveling wave time of arrival measured at both ends of transmission line combined with associated fault locations form a fault pattern which is used to perform a simple calculation in order to determine the disturbance location. The fault current for different fault locations is simulated using the electromagnetic transient simulation software EMTDC/PSCAD. Performance of the proposed fault location algorithm is investigated using various fault location and resistance. The impact of data sampling rate also being investigated here. The simulation result shows that the proposed algorithm can reduce the sampling frequency and the number of train feature with the same accuracy.

Traveling wave method for simulating geometric beam coupling impedance of a beam screen with pumping holes

In particle accelerators, pumping holes in a vacuum chamber can be a source of unwanted broadband coupling impedance, leading to beam instabilities. Analytical methods have been previously developed to estimate the impedance of holes in circular-like chambers e.g. the beamscreen of the Large Hadron Collider (LHC). More sophisticated chamber designs like that of the High Energy LHC (HE-LHC) and the Future Circular Collider (FCC-hh) call for a different way to calculate the impedance. We propose using decomposition of the wakefield into synchronous traveling waves and employing a numerical solver to find the impedance of each wave. This method is compared to the direct time domain wakefield calculation method and its greater sensitivity to small impedances is shown.

W-shaped and bright optical solitons in negative indexed materials

Abstract We investigate a generalized nonlinear Schrodinger equation with higher-order effects such as pseudo-quintic nonlinearity and self-steepening effect. The model applies to the description of ultrashort pulse propagation in nonlinear materials exhibiting a negative index of refraction. Three new types of nonlinearly chirped W-shaped soliton solutions are derived for the first time by using the traveling-wave method. The obtained structures have new functional forms that are distinct from the usual W-shaped soliton solution reported within the context of optical fibers. An important characteristic of these envelope solitons is the nonlinear chirp that is directly proportional to the intensity of the pulse. It is shown that these chirped W-shaped structures are formed as a result of the exact balance among the group velocity dispersion, the self-steepening effect, and the pseudo-quintic nonlinearity. Exact chirped bright soliton solutions of the model were also obtained under appropriate conditions. Our results may raise the possibility of some experiments and potential applications related to left-handed materials in the presence of self-steepening nonlinearity.

Asynchronous fault location scheme for half‐wavelength transmission lines based on propagation characteristics of voltage travelling waves

Due to prominent attenuation of travelling waves, double-end fault location method produces considerable errors when applied to ultra-high voltage AC half-wavelength transmission (UAHT) lines. In order to address this problem, this study presents a novel fault location scheme based on the attenuation, refraction and reflection principles of aerial-mode voltage travelling waves (AVTWs). In the scheme, the faulted section of an UAHT line is first determined according to the accumulated amplitude ratio of the pre-determined frequency components of AVTWs asynchronously sampled at both terminals of the line. Then, the Teager energy of the first two wavefronts of the AVTW - measured at the terminal in the faulted section - is used to define two factors for selecting the appropriate accurate fault location method. Finally, the single-end travelling wave method is adopted for locating the faults near the line terminal. The presented double-end method utilises the amplitude ratio of AVTWs to locate the faults far from the line terminal. A 1000 kV UAHT line model is considered with various fault conditions in PSCAD/EMTDC simulations. The simulation results and analysis demonstrate that the proposed fault location scheme is accurate and immune to fault distances, fault types, fault impedances and fault inception angles.

Analytical solutions of fractal-hydro-thermal model for two-phase flow in thermal stimulation enhanced coalbed methane recovery

Thermal stimulation is a useful supplementary mining technique for the enhancement of coalbed methane recovery. This technique couples the temperature change with gas-water two-phase flow in the mining process. Many integer dimension hydro-thermal models have been proposed but cannot well describe this coupling because two-phase flow and heat conduction are usually non-linear, tortuous and fractal. In this study, a fractal-hydro-thermal coupling model is proposed to describe the coupling between heat conduction and two-phase flow behaviors in terms of fractional time and space derivatives. This model is analytically solved through the fractal travelling-wave method for pore pressure and production rate of gas and water. The analytical solutions are compared with the in-situ coalbed methane production rate. Results show that our proposed fractal-hydro-thermal model can describe both heat and mass transfers in thermal stimulation enhanced coalbed methane recovery.

Traveling-wave fault location algorithms in hybrid multi-terminal networks with a tree-like structure

Traveling-wave methods of the fault location prove their practical efficiency for the power transmission lines (TL) with an arbitrary configuration of any voltage class. This paper formulates algorithms to automate the process of the fault location in the TLs with a tree-like structure. The error of the simplified traveling-wave fault location (TWFL) algorithm based on the average propagation velocity of the transient signals (TS) is analyzed. A tabular algorithm for TWFL, which considers different propagation velocities of the TS in different segments of a hybrid network is proposed. An adaptive TWFL algorithm that considers the registration of the TSs with known places of their occurrence is proposed, to reduce the impact of the inaccuracy of the initial different network segments’ lengths and TS’s propagation velocity determination.

Exact chirped singular soliton solutions of Triki-Biswas equation

Triki and Biswas proposed an important generalization of the derivative nonlinear Schrödinger equation that could be a model equation of ultrashort pulse propagation in optical fiber systems beyond the Kerr limit. This paper studies the exact nonlinearly chirped singular soliton solutions of the Triki-Biswas equation with non-Kerr dispersion by means of the traveling-wave method. The results show that these envelope solitons possess a nontrivial phase chirping which varies as a function of the wave intensity. The conditions on the optical material parameters for the existence of the singular structures are also presented.

Distributed Traveling-Wave-Based Fault-Location Algorithm Embedded in Multiterminal Transmission Lines

A novel traveling-wave-based fault-location algorithm for multiterminal transmission lines is introduced in this paper. Existing traveling-wave fault-location methods that based on the data measured at line terminals lack reliability and accuracy because time synchronization is needed, which brings error. To solve this problem, the complex structure of multiterminal power system is divided into several fault identification branches, current at the midpoint of each branched is measured, a novel fault-location algorithm is proposed, and the time synchronization error is eliminated. A line-based device is designed to measure the current at the midpoint of each branch. An accurate value of the traveling wave speed can be obtained by merely applying the data record in one measuring device. Thus, the fault-location accuracy is improved. The system model applied in this paper comprises one transmission line and two tapped lines, and the proposed method applies to networks with more terminals. Performance of this method is tested by different cases by PSCAD. The hardware platform has been tested in Sichuan Province, China.

A spline ROM of blade aerodynamic force to upstream wake

All related research nowadays are devoted to build ROM of aerodynamic forces induced by vibration of blades or wings. There is no discussion of ROMs of the aerodynamic forces of the blades corresponding to upstream wakes, which is more important to turbine machines' safety. In this paper, a spline Volterra ROM method is proposed to predict the blades' aerodynamic forces induced by the upstream wakes to fasten the blade–wake interaction analysis in turbine machine design. Traveling wave method is applied to simplify the inputs representing the upstream wakes. The kernels of the Volterra ROM are expressed in spline to reduce the number of parameters to be identified. The coefficients of the spline kernels are identified by minimizing the difference between ROM results and CFD data. The ROM method is used to predict a blade's aerodynamic forces under an actual wake. The results show that the ROM can capture most information of the aerodynamic forces due to the wake.

Families of exact solutions of the generalized (3+1)-dimensional nonlinear-wave equation

In this paper, the traveling wave method is employed to investigate the one-soliton solutions to two different types of bright solutions for the generalized (3[Formula: see text]+[Formula: see text]1)-dimensional nonlinear-wave equation, primarily. In the following parts, we derive the breathers and rational solutions by using the Hirota bilinear method and long-wave limit. More specifically, we discuss the lump solution and rogue wave solution, in which their trajectory will be changed by varying the corresponding coefficient or coordinate axis. On the one hand, the breathers express the form of periodic line waves in different planes, on the other hand, rogue waves are localized in time.

Application of Travelling Wave Method for dynamic analysis of plane frame structures

The dynamic behavior of a structure can be formulated in terms of the waves propagating through its members. This approach is commonly known as the Travelling Wave Method (TWM). The propagation of an external excitation within structural members, and the behavior of waves at a discontinuity are defined by the amplitude of displacement waves, and the wave reflection and transmission coefficients. The assemblage of these properties provides a concise method to formulate the dynamic response of structures. Although it has been used for the analysis of aerospace structures, the TWM has rarely been used for the analysis of civil engineering structures. This paper presents the theoretical basis and the formulation of the wave-propagation approach to analyze the dynamic response of civil-engineering-type structures, and discusses its advantages over the commonly used Finite Element Method (FEM). It is shown by examples that TWM requires less computational time than FEM, can incorporate the frequency-dependent soil–structure interaction effects in the analysis directly, and gives more accurate results at high frequencies. The last one is particularly important for detecting small and invisible damages in structures, since most of such damage is hidden in high frequencies.

Influence on Traveling Wave Fault Location from Structural Characteristics of Railway Automatic Blocking Electric Lines

This paper, taken the railway 10kV automatic blocking electric line as the research object, discusses some structure factors which may affect the ranging accuracy of traveling wave method in the practical application of traveling wave fault location device, and establishes the simulation model to verify. These structure factors include the effect of transition resistance, terminal load combination form and the line branches' number before fault point.

Chirped envelope optical solitons for Kaup–Newell equation

We investigate the Kaup-Newell equation that represents one of the forms of derivative nonlinear Schrödinger equation. The model applies to the description of sub-pico-second pulse propagation through an optical fiber. A special complex envelope traveling-wave method is applied to find a nonlinear equation with a fifth-degree nonlinear term describing the dynamics of field amplitude in the nonlinear media. It is shown that the phase associated to the obtained pulses has a nontrivial form and possesses two intensity dependent chirping terms in addition to the simplest linear contribution. A class of soliton solutions of the bright, dark and singular type are derived for the first time. The requirements concerning the optical material parameters for the existence of these chirped structures are also discussed.