Relay Protection Method of High Voltage Transmission Line Based on Time-frequency Analysis

Based on the wavelet transform results of the transient signals from all ends of the line, a unit protection for high voltage power transmission line is presented. The attenuation effects of high voltage transmission line and busbar capacitance to high-frequency current signals are analyzed. The Transient Current Content Ration(TCCR), Transient Voltage Content Ratio (TVCR) and Transient Voltage Singularity Ratio (TVSR) are deduced according to the analysis of the differences during high frequency voltage transients at each end of the transmission line when in-zone faulted and out-zone faulted. Protection criterion using TCCR and protection criterion using TVSR are proposed, and the principles of protection settings are given. The wavelet modulus maxima of transient signals are used to calculate TCCR and TVSR. Simulation experiments of different faults with EMTP are carried out to test and analyze the protection criteria. A 100kHz sampling rate is used in the simulation experiments. According to the simulation results, the protection criteria prove to be simple, reliable and good for whole line protection.

Impact of high-voltage power transmission lines on photovoltaic power production

This paper presents a new approach for calculation of fault location on high voltage transmission lines. The proposed fault location algorithm utilizes statistical information about the equivalent impedances of the system at the unmonitored end of the transmission line. Knowledge about the distribution laws of these values or their numerical characteristics, which are more accessible for practical use, results in more accurate fault location for lines with grounded neutral, especially in case of distant short circuit through the large transient resistance. The proposed algorithm is based on modelling of the faulted line and the method of Monte-Carlo. The utilized line model with distributed parameters is described by two-port network theory equations. The algorithm automatically eliminates the effect of line shunt capacitance and calculates not only the expected value of the distance to the fault, but also another important additional characteristic for the fault location, namely, the length of the line segment, where short circuit may have occurred. Furthermore, the possibility to reduce the costs on the inspection of transmission line faulted segment and fault point location is described in the paper.

High voltage transmission lines are the fundamental element in order to transfer electricity from the power plant/grid to consumers. The frequency, current and voltage are the key figures to sustain the absolute quality of the power transmission, and maintaining such high performance requires smart solutions and equipment like Current Transformer (CT) & Potential Transformer (PT). This proposed work enlightens an inception to monitor current in the high voltage transmission lines by using pyro-sensors, machine learning (ML) techniques and artificial intelligence (AI). Using pyro-sensors around the transmission/distribution lines, data will be gathered about the heat waves (infrared waves) generated by the electric current in the transmission/distribution line. The proposed methodology uses this data to be processed by neural network based artificial intelligent algorithm to evaluate the amount of current in the transmission line. The claim about the authenticity of the proposed technique is tested and verified by MATLAB simulation neural network toolbox.

Transmission lines are an important part of a power system. Transmission lines have high power transmission capacity and they are prone to faults of larger magnitudes. Various faults occur in transmission lines. Therefore, protection relays are necessary to protect transmission lines. The purpose of protection system is to interrupt the faulty section from the healthy section because the fault currents may damage the electrical equipments. One of the protection relays is distance relay and it is mainly used in transmission line. Sometimes these relay are used for backup protection. Distance relays for determining the impedance need the voltage and current. Transmission lines are typically protected by distance protection relay. Distance relays are considered of high speed class and can provide transmission lines. Nowadays, numerical distance relays have been used instead of using electromechanical and static distance relays. The proposed model was verified under different tests such as single line to ground (L-G) fault, double line to ground (L-L-G) fault, line to line (L-L) fault and three phase (L-L-L) fault. SimPower System was used for modelling and simulation of distance relay, transmission lines and faults. The simulation results were obtained from MATLAB software shows the feasibility of analysis of transmission line protection with mho type distance relay for single line to ground fault, double line to ground fault, line to line fault and three phase fault at different location of transmission lines. The difficulties understanding on operation of distance relay can be cleared by using MATLAB/SIMULINK software.

In respect to the difficulties in power supply for online monitoring equipments at high voltage side, a new design of adjustable and rechargeable induction power supply is presented. A microprocessor is used as the central control unit, which can achieve the intelligent management and control of different modules of the proposed device. The experimental results show that reliable and stable power output can be obtained in the situation of large current variation. Introduction The security and stability of the high voltage transmission lines are very important in the development of smart grid. As a result, different kinds of auxiliary devices are installed on high voltage transmission lines to improve the capability of condition monitoring [1]. However, due to the electrical isolation of safety requirements [2], the electronic monitoring equipments installed on the high voltage side can not be directly powered from the low voltage side. Therefore, the power supply has become one of the key technologies which restrict the development of online monitoring systems. The traditional power supplies, for example, solar energy [3], are unable to provide the monitoring equipments an all-weather, continuous and stable power supply. The induction power supply at high voltage side can work in harsh weather and provide stable and continuous output [4], which makes it an ideal choice for online monitoring equipments to solve their energy supply problem. However, since the current of the transmission lines varies in a wide range, it is crucial how to ensure that the induction power supply device has a stable and reliable output with a wide range of current fluctuation. It is necessary to ensure that the power supply can provide sufficient driving power to the online monitoring equipment when the current of the transmission line is small [5]. It is also needed to ensure that when large current flows in the transmission line, a sustainable and stable power supply still can be obtained. Therefore, a new design of adjustable and rechargeable induction power supply at high voltage side is studied. The proposed induction power supply can produce reliable and stable power supply in the condition of large current variation. The Structure of the Proposed Power Supply Fig. 1. The overall framework of the proposed induction power supply The proposed induction power supply consists of the power capture module, the rectifier module, the over-voltage protection module, the voltage regulator module, the backup power management 4th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2016) © 2016. The authors Published by Atlantis Press 1195 module and the microprocessor control unit (MCU), as shown in Fig. 1. With the MCU, the entire device can be intelligently controlled to produce a stable DC voltage output even with a large current variation in the transmission line [6]. The details of each module of the proposed induction power supply are presented as follows. Power Capture Module. The structure of the power capture module is shown in Fig. 2. The actual current in the high-voltage transmission lines keeps changing. In order to adapt to the dynamic current changes, there are multiple taps at the CT coil in the secondary side. Different taps correspond to coils with different numbers of turns. With the sampling resistor in the rectifier module, the MCU can achieve a real-time control on the number of coil turns. When the current in the transmission line is too large, the current at the secondary side also becomes large. The MCU controls the relay 1 and then the coil 1 will be connected to the circuit in order to reduce the current at the secondary side. When the current in the transmission line is in normal variation, the MCU controls the relay 1 and then the coil 2 is connected. Finally, if the current in the transmission line is too small, then the backup battery may be switched on to power the equipment. Such a design makes the proposed device having efficient power capture capability over a wide range of current variations. Fig. 2. The structure of the power capture module Rectifier Module. Rectifier circuit DB107 is used in this design. RC filter and LC filter are connected in parallel. A transient suppression diode TVS, which plays the role of over-current protection, is inserted between the rectifier circuit and the filter. The selected TVS is SMF45A, which has a breakdown voltage of 75 V and a cut-off voltage of 45 V. Fig. 3. The structure of the rectifier module Voltage Regulator Module. The voltage of the DC output of the rectifier module is 7.5 V – 76 V. The role of the DC-DC voltage regulator module is to convert this wide range of input voltage into a stable but adjustable output voltage. In our design, the step-down voltage converter MAX5035BASA is chosen as the core unit of this module. It has high efficiency and wide input voltage range up to 76 V. Its output voltage is fixed to 5 V. Fig. 4 shows the circuit of this module.

A parametric analysis of lightning stroke incidence to high voltage (HV) transmission line towers is presented in this paper. It is based on a mathematical model that accounts for the transmission line geometry, keraunic level, statistical distribution of lightning current parameters and correlation between statistical variables defining the lightning current waveshape. Theoretical analysis is backed by the most recent propositions of parameters that define statistical distributions and then applied to the typical HV transmission line example. The results provide insight into the selection procedure for the lightning current parameters (i.e. amplitude, front duration, wave duration and polarity) associated with lightning stroke incidence to transmission line towers. This selection procedure could be applied in backflashover analysis as well as in the analysis (and design) of HV transformer station overvoltage protection. Copyright © 2010 John Wiley & Sons, Ltd.

Fault location and distance protection in transmission lines are essential smart grid technologies ensuring reliability of the power system and achieve the continuity of service. The objective of this chapter is to presents an accurate algorithm for estimating fault location in Extra High Voltage (EHV) transmission lines using Artificial Neural Networks (ANNs) for high speed protection. The development of this algorithm is based on disturbed transmission line models. The proposed fault protection (fault detection/classification and location) uses only the three phase currents signals at the one end of the line. The proposed technique uses five ANNs networks and consists of two steps, including fault detection/classification and fault location. For fault detection/classification, one ANN network is used in order to identify the fault type; the fault detection/classification procedure uses the fundamental components of pre-fault and post-fault sequence samples of three phase currents and zero sequence current. For fault location, four ANNs networks are used in order to estimate the exact fault location in transmission line. Magnitudes of pre-fault and post-fault of three phase currents are used. The ANNs are trained with data under a wide variety of fault conditions and used for the fault classification and fault location on the transmission line. The proposed fault detection/classification and location approaches are tested under different fault conditions such as different fault locations, different fault resistances and different fault inception angles via digital simulation using MATLAB software in order to verify the performances of the proposed methods. The ANN-based fault classifier and locator gives high accuracy for all tests under different fault conditions. The simulations results show that the proposed scheme based on ANNs can be used for on-line fault protection in transmission line.

The high voltage transmission line directly or indirectly damages the surrounding environment. This is an immediate problem for residents, business operators and the government. It causes a great social cost. In this study, the influence of the high voltage transmission line on the surrounding land is analyzed through case studies. This study investigated the survey and transaction cases in the relevant area. The results of the study are summarized as follows: First, the high voltage transmission line caused by the large-scale development project gives psychological anxiety and disgust to the residents. It is expressed and recognized as physical, visual, and noisy inconveniences. Second, it is rarely traded around high voltage transmission lines and there are very few transactions in the area affected by the lines. Third, in-depth investigation and analysis of repeated transactions showed about 5% stigma effect. The limitations and challenges of the research are as follows. It is necessary to analyze empirically as considering the fact that most of the existing high-voltage transmission line studies lacks a specific analysis when dealing with public land(house) prices or transactions. Various case studies are required to solve the current dispute related to the high-voltage transmission line. A reasonable alternative to social conflicts should be presented through continuous empirical research.

TWIN Source (TS) experimental setup is a stepping stone towards INTF, a test-bed to characterize ITER Diagnostic Neutral Beam (DNB) and its ion source. in IPR, India. The electrical system for TS experiments involves design of the scheme, layout, procurement activities, testing, installation & commissioning of power supplies, LT Panels, cables, High Voltage (HV) transmission line, HV deck, RF shielding, grounding and bonding for its safe, reliable and successful operation. The operation of TWIN source will try to mimic some operational features of INTF / DNB source like, 5Hz modulation with 3s ON 20s OFF duty cycle, Few kA current through Plasma Grid (PG) ,based transverse magnetic field electrical feedthroughs through high voltage bushing (HVB) and source operation in vacuum immersed condition. The control of those power supplies will be carried out through CODAC type data acquisition and control platform. The TS electrical system comprises of 180kW 1MHz RF Generator (RFG) system, Filament Heating power supply (16VDC, 10A), Filament Bias power supply (128VDC, 1A), Grid Bias power supply (60VDC, 333A), Filter field power supply (3VDC, 6kA), 150kVA 50Hz 100kVDC isolation transformer, HV transmission line, Air Circuit Breaker (ACB) based LT Panel of 1600A and 800A with 50kA breaking current capacity. This paper discusses the schematic layout of the electrical system, operational modes of 180kW 1MHz RFG including the interfaces with cooling water system and electrical interface with CODAC type Data Acquisition & Control System (DACS). It also discusses the design of HV transmission line & its prototype, shielding, grounding & bonding and highlights the design considerations to mitigate challenges of HV isolation during beam extraction & acceleration mode.

In the process of monitoring and repairing, it is difficult to measure wire net signal of power systempsilas high voltage power transmission lines accurately. In order to solve this problem, the signal measured in remote substation or laboratory is employed to make multipoint prediction to gain the needed data, and then the predicted data is send to work-field via wireless network GPRS. The needed precise data may be computed based on current time and received data in work-field, which may provide reliably basis for fault diagnosis of air bracket high voltage power transmission lines. Here, RBF neural network is employed to identify and predict the needed time signals. In order to overcome the shortcoming of general RBF net that convergence speed is slow and plunge local extremum easily, a practical learning algorithm was proposed for adjusting the node number, centers and width of Gaussian function of hidden layer nodes effectively. Off-line training and on-line identifying were combined together to train networks and identify wire net signal. Simulation experiment shows that the designed RBF network having good predicting ability, which offers accurate data for the monitoring and fault diagnosis of high voltage power transmission lines.

Transmission line protection is an important issue in power system engineering because 85-87% of power system faults are occurring in transmission lines. This paper presents a technique to detect and classify the different shunt faults on a transmission lines for quick and reliable operation of protection schemes. Discrimination among different types of faults on the transmission lines is achieved by application of evolutionary programming tools. PSCAD/EMTDC software is used to simulate different operating and fault conditions on high voltage transmission line, namely single phase to ground fault, line to line fault, double line to ground and three phase short circuit. The discrete wavelet transform (DWT) is applied for decomposition of fault transients, because of its ability to extract information from the transient signal, simultaneously both in time and frequency domain. The data sets which are obtained from the DWT are used for training and testing the SVM architecture. After extracting useful features from the measured signals, a decision of fault or no fault on any phase or multiple phases of a transmission line is carried out using three SVM classifiers. The ground detection task is carried out by a proposed ground index. Gaussian radial basis kernel function (RBF) has been used, and performances of classifiers have been evaluated based on fault classification accuracy. In order to determine the optimal parametric settings of an SVM classifier (such as the type of kernel function, its associated parameter, and the regularization parameter c), fivefold cross-validation has been applied to the training set. It is observed that an SVM with an RBF kernel provides better fault classification accuracy than that of an SVM with polynomial kernel. It has been found that the proposed scheme is very fast and accurate and it proved to be a robust classifier for digital distance protection.

Studies have shown that the sources of ultraharmonic pair multiplicity are nonlinear network elements, especially autotransformers in the mode of low loads, when the operating point is outside the linear part of the magnetization characteristic. Ultraharmonic pairs of voltage and current multiplicity were recorded during the operation of the transmission line. As a result of the analysis of the conditions of resonant overvoltages due to the appearance of the paired ultraharmonic voltage in the high voltage transmission lines, the calculated expressions are obtained and a mathematical model for estimating the resonant frequency in current and prospective power transmission is developed. The calculations of the resonant frequency of the input resistance of the high voltage transmission line are performed depending on the mode parameters and the composition of the connected main equipment. It is determined that the value of equivalent system resistance has the greatest influence on the resonant frequency. The reasons of even harmonic appearance are described.

Energy flow bottlenecks in high voltage transmission lines known as congestions are one of the challenges facing power utilities in fast developing countries. Bottlenecks occur in selected power lines when transmission systems are operated at or beyond their transfer limits. In these cases, congestions result in preventing new power supply contracts, infeasibility in existing contracts, price spike and market power abuse. The “Superconductor Technology” in electric power transmission cables has been used as a solution to solve the problem of bottlenecks in energy transmission at high voltage underground cables and overhead lines. The increase in demand on power generation and transmission happening due to fast development and linked to the intensive usage of transmission network in certain points, which in turn, lead to often frequent congestion in getting the required power across to where it is needed. In this paper, a bottleneck in high voltage double overhead transmission line with Aluminum Conductor Steel Reinforced was modeled using conductor parameters and replaced by Gap-Type Superconductor to assess the benefit of upgrading to higher temperature superconductor and obtain higher current carrying capacity. This proved to reduce the high loading of traditional aluminum conductors and allow more power transfer over the line using superconductor within the same existing right-of-way, steel towers, insulators and fittings, thus reducing the upgrade cost of building new lines.

The complexity of transient processes during travelling-wave propagation in extra high voltage overhead lines is deter-mined by the fact that many frequency components are presented in the electromagnetic wave front. For the correct analysis of the aforementioned transient processes and for further development of travelling-wave-based relay protec-tion and fault location devices, it is necessary to take into account the parameters of the environment where electromagnetic wave propagation occurs. For the transmission line, these parameters are longitudinal inductance, longitudinal resistance, shunt capacitance and shunt resistive conductance. It is worth mentioning that for a variety of reasons unit-area longitudinal inductance and resistance are the parameters which depend on frequency, thus travelling wave velocity is different for different frequency components of the electromagnetic wave front. The popular researches which address this problem either fail to consider the dependence of overhead line inductance and resistance on frequency or this dependence is considered approximately for the high-frequency range, which can cause significant errors in the transient processes analysis during travelling wave propagation. In view of this, the development of the approach to overhead transmission lines simulation, which will allow both determining the line parameters in a wide frequency range and evaluating steady-state behaviour and transient processes in long-distance transmission lines, arrears relevant. The main research method to establish extra-high voltage transmission line parameters employs the simulation study in COMSOL Multiphysics. A number of assumptions were made in the simulation process: homogeneous soil layer, entire transmission line section and absence of transmission line conductor sag. The usage of finite elements method (FEM) for differential equation solution in the above-mentioned software is also seen as an assumption. The approach to extra-high voltage transmission lines simulation has been offered. This approach consists of the usage of Maxwell’s equations in combination with numerical integration with finite elements method (FEM). Frequency response for transmission line parameters and travelling-wave propagation velocity rate for different frequency components have been obtained. The results obtained can be used in updating of electrical power system models for further research in the relay protection field. The suggested approach will allow evaluating line parameters of other voltage types and obtaining more accurate values of transmission line parameters and travelling wave propagation speed along transmission lines for high-frequency range. The use of these transmission line models will enable to formulate approaches to improve the existing algorithms of travelling-wave-based relay protection and fault location devices.