Distance Protection Of Transmission Lines Research Articles

Study on a New Earth-Fault Distance Protection for Four-Circuit Transmission Lines on the same Tower

Since the transmission corridors are becoming more and more valuable and the demand for transmission capacity is continually increasing, the four-circuit transmission lines on the same tower have been used more and more in the high-voltage system. For this complex transmission system, there is an unpredictable mutual inductance error when measures the impedance, which will potentially cause the mal-operation of relay. Therefore, it is not feasible to use the traditional earth-fault distance protection in case of the single phase to earth fault. In this paper, twelve-sequence components method is introduced to decouple mutual electromagnetic effect between four-parallel transmission lines. Based on the analysis of the features of each component, the relationship between fault voltage and the current is presented. Furthermore, a new protection criterion for earth-fault distance protection is proposed. The new method has high sensitivity and reliability under different scenarios.

Adaptive distance protection of transmission line in presence of SVC

In this paper, the analytical and simulation results of the application of adaptive distance protection scheme for the transmission line incorporating Static Var Compensator (SVC) connected at the mid-point is presented. The mal-operation of the distance protection for the transmission line with SVC at various locations are studied. The simulation results show the under-reaching and over-reaching is more severe with SVC at mid-point of the transmission line. To mitigate the mal-operation of the distance protection, the adaptive scheme is presented based on recursive simulation study. The simulation result with adaptive scheme is outperformed as compared with the conventional scheme. Electro-magnetic Transient Program (EMTP) simulations on two machine system is used to substantiate the claim.

Equal transfer processes-based distance protection of EHV transmission lines

The overreach of the distance protection caused by CCVT is still a serious problem for high-speed line protections. Based on the theory of Equal Transfer Process of Transmission Lines (ETPTLs), a new high-speed distance relay scheme is proposed in order to overcome above problem. The solution is to make the three-phase voltages and currents at the relay location and the voltage at the fault point have the same transfer links by virtue of a new design. Three major steps of the new method are demonstrated: re-structuring of the voltage at the fault point, the virtual digital transfer method and solving the R–L differential equation. A variety of ATP simulation tests show that the new method effectively reduces the transient error caused by CCVT and improves the operating speed by a series of technical countermeasures including three major steps, iterative calculations of the fault distance and an inverse time delay setting criterion. The distance measuring error is within 5% at approximately 15ms after fault occurrence, which is superior to various adaptive protection algorithms based on CCVT transient error estimation or source impedance ratio (SIR).

Distance Protection for HVDC Transmission Lines Considering Frequency-Dependent Parameters

For distance protection, the measurement accuracy at the boundary of protective zone is the most important issue to distinguish internal faults from external faults correctly. Since the line parameters depend strongly on the frequencies, in order to obtain high accuracy, it should be considered during initial fault transients generally associated with plentiful harmonics. In this paper, a distance protection method considering a frequency-dependent parameters is introduced into HVDC transmission lines. According to transmission-line equations, the frequency-dependent parameter model is separated into two parts: 1) distributed parameter model and 2) a compensation matrix related to frequency-dependent parameters, and the latter is approximated in the time domain with finite impulse response filters. So the voltage and current at the setting point are calculated accurately using local sampling data, and the fault distance is obtained by solving differential equations. The proposed algorithm is able to enhance the calculation accuracy of fault distance greatly at the remote-end faults. Furthermore, it is performed in the time domain and, thus, a short data window is sufficient for it to achieve satisfactory accuracy. Simulation results show that this method is valid and is capable of detecting the faults occurring on the protected line quickly and accurately.

The Modeling and Simulation Research on High-Voltage Transmission Line Distance Protection Devices

The Modeling and Simulation Research on High-Voltage Transmission Line Distance Protection Devices

A novel method for adaptive distance protection of transmission line connected to wind farms

Wind speed variations results in wind farm voltage, frequency and power output fluctuations. Therefore, protection of lines connecting such a farm to the grid is very important and an adaptive system for distance protection of such a line is necessary. In this paper, an adaptive unit which adjusts the relay trip characteristic using local information has been designed for distance relay using artificial neural networks. In this case, in order to prevent wrong operation of relay, changing in wind farm conditions, the set points of different zones of distance relay has to be changed simultaneously. The results obtained from proposed method are verified by computer simulation.

Digital distance protection of transmission lines in the presence of SSSC

In this paper the impact of Static Synchronous Series Compensator (SSSC) on the impedance calculated by distance relay is investigated. Analytical results are presented and verified by detailed simulations. Six different phase to phase and phase to ground measuring units of the distance relay are simulated to resemble the behavior of the relay. It is shown in this paper that zero sequence of the injected voltage by 48 pulse SSSC converter has the most impact on the apparent impedance seen by the phase to ground fault measuring unit and cause under reaching of distance relay. It can be concluded from the results that SSSC located in the middle of the transmission line cause to divide trip characteristics of distance relay into two separate parts. It is also shown that the over-reaching operation of distance relay might happen in some cases in the presence of SSSC. All the detailed simulations are carried out in MATLAB/Simulink environment.

Adaptive distance protection of a double circuit transmission line

Adaptive distance protection of a double circuit transmission line

Impact of VSC-Based Multiline FACTS Controllers on Distance Protection of Transmission Lines

By utilizing multiline voltage-source (VSC)-based flexible ac transmission system (FACTS) controllers, independent controllability over each compensated line of a multiline system can be achieved. While VSC-based multiline FACTS controllers emerged as a new opportunity to control two independent ac systems, the main constraints and limitations that are presented to the conventional transmission-line protection systems need to be investigated. In this paper, the impacts of VSC-based FACTS controllers on distance relays while controlling the power flow of compensated lines are evaluated analytically and by detailed simulations for different fault types and locations.

An Adaptive Decision Logic to Enhance Distance Protection of Transmission Lines

This paper introduces adaptive decision-making logic to improve the performance of distance protection of transmission lines. The proposed approach incorporates the trajectory of the measured impedance into the relay final decision-making logic through a weighting procedure. Two criteria are used to weigh the impedance plane appropriately, where higher weights are assigned to the faults occurring at the interior areas of the relay protective zone and low resistance faults. The weights assigned to impedance samples are added together considering the amount of smoothness of the measured impedance trajectory. An adaptive neurofuzzy inference system (ANFIS) is used to implement the proposed decision logic. Meanwhile, the fault current amplitude is considered as the other input of the ANFIS network to accelerate the relay operation for close-in faults and to incorporate an index for the source-to-line impedance ratio into the final decision-making logic. Extensive simulation studies using PSCAD/EMTDC software indicate that the proposed approach provides a very reliable technique to make the distance protective scheme faster and smarter. It helps to achieve the optimal compromise between the protective relay operation time and security.

Laboratory Investigation of IEC 61850-9-2-Based Busbar and Distance Relaying With Corrective Measure for Sampled Value Loss/Delay

After successful implementation of IEC 61850-8-1-based GOOSE at several power substations worldwide, major protective device vendors are currently developing interoperable products for IEC 61850-9-2-based time-critical sampled value (SV) messages over the digital process bus. Unlike GOOSE, the same SV message is not repeated several times and, therefore, it is important to analyze the impact of SV loss or delay on protection functions. This paper presents the hardware implementation of a typical IEC 61850-9-2-based process bus communication network for digital protection systems to investigate the proposed corrective measure for SV loss/delay. For the detailed testing, various process bus devices (e.g. protection intelligent electronic devices (IEDs), merging units (MUs), etc.) are developed over industrial embedded systems with a hard-real-time platform. The SV estimation algorithm is implemented as a part of bus differential and transmission-line distance protection IEDs, and it is tested for various SV loss/delay scenarios and power system fault conditions.

STATCOM/SVC impact on the performance of transmission line distance protection

AbstractThe impact of 48‐pulse STATCOM/SVC on the apparent impedance seen by the transmission line distance relay is investigated in this paper. Analytical results are presented and verified by detailed simulations. The STATCOM/SVC control systems are modeled in full details and practical constraints are applied. It is shown that the presence of a current limiter in the control system of STATCOM could significantly mitigate the impact of STATCOM on the relay's calculated apparent impedance. Six different phase‐to‐phase and phase‐to‐ground measuring units of the distance relay are simulated to resemble the behavior of the relay. It is shown that the impact of SVC on the apparent impedance seen by the phase‐to‐ground fault measuring units is more pronounced. Different power system operating conditions, STATCOM/SVC control system settings and fault scenarios are considered in the simulations. The STATCOM/SVC effects on the distance relay tripping characteristics are also analyzed. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Genetic algorithms applied to a faster distance protection of transmission lines

The main purpose of this paper is to implement a new methodology based on Genetic Algorithms (GAs) to extract the fundamental voltage and current phasors from noisy waves in power systems to be applied to a faster distance protection. GAs solve optimization problems based on natural selection principles. This application was then formulated as an optimization problem, and the aim was to minimize the estimation error. A 440 kV, 150 km transmission line was simulated using the ATP (Alternative Transients Program) software in order to show the efficiency of the new method. The results from this application show that the global performance of GAs was highly satisfactory concerning speed and accuracy of response, if compared to the traditional Discrete Fourier Transform (DFT).

Improvement of distance protection of overhead transmission lines rated over 1000 V having self-supporting insulated wires under electromagnetic impact of railroad AC networks

The principle scheme and parameters of overhead transmission line distance protection capable of detecting a rupture of a self-supporting insulated wire over 1000 V hanging on railroad AC towers are presented. The protection is based upon phase-to-ground voltage measurement at a line end made in a resistor-capacitor zero-sequence compensation cubicle. A communication carried out over the overhead transmission line.

Wavelet entropy based algorithm for fault detection and classification in FACTS compensated transmission line

Distance protection of transmission lines including advanced flexible AC transmission system (FACTS) devices has been a very challenging task. FACTS devices of interest in this paper are static synchronous series compensators (SSSC) and unified power flow controller (UPFC). In this paper, a new algorithm is proposed to detect and classify the fault and identify the fault position in a transmission line with respect to a FACTS device placed in the midpoint of the transmission line. Discrete wavelet transformation and wavelet entropy calculations are used to analyze during fault current and voltage signals of the compensated transmission line. The proposed algorithm is very simple and accurate in fault detection and classification. A variety of fault cases and simulation results are introduced to show the effectiveness of such algorithm.

Comprehensive Adaptive Distance Relaying Scheme for Parallel Transmission Lines

Reach accuracy of a distance relay is adversely affected by prefault system conditions, ground fault resistance, shunt capacitance, and mutual coupling of parallel lines. This paper presents a comprehensive adaptive relaying scheme for stand-alone distance protection of parallel transmission lines under a single-line-to-ground fault condition taking into account all of these factors. The proposed adaptive scheme is based on the back-propagation neural network used for training and adaptation. The relay acts as a stand-alone relay, which does not require a separate communication channel for real-time data transmission during faults. The simulation results show significant improvement in the relay selectivity.

Transmission lines distance protection using artificial neural networks

This work presents the development and implementation of an artificial neural network based algorithm for transmission lines distance protection. This algorithm was developed to be used in any transmission line regardless of its configuration or voltage level. The described ANN-based algorithm does not need any topology adaptation or ANN parameters adjustment when applied to different electrical systems. This feature makes this solution unique since all ANN-based solutions presented until now were developed for particular transmission lines, which means that those solutions cannot be implemented in commercial relays.

Wavelet Entropy Based Algorithm for Fault Detection and Classification in FACTS Compensated Transmission Line

Abstract Distance protection of transmission lines including advanced flexible AC transmission system (FACTS) devices has been a very challenging task. FACTS devices of interest in this paper are static synchronous series compensators (SSSC) and unified power flow controller (UPFC). In this paper, a new algorithm is proposed to detect and classify the fault and identify the fault position in a transmission line with respect to a FACTS device placed in the midpoint of the transmission line. Discrete wavelet transformation and wavelet entropy calculations are used to analyze during fault current and voltage signals of the compensated transmission line. The proposed algorithm is very simple and accurate in fault detection and classification. A variety of fault cases and simulation results are introduced to show the effectiveness of such algorithm.

Wavelet Entropy Based Algorithm for Fault Detection and Classification in FACTS Compensated Transmission Line

Distance protection of transmission lines including advanced flexible AC transmission system (FACTS) de-vices has been a very challenging task. FACTS devices of interest in this paper are static synchronous series compensators (SSSC) and unified power flow controller (UPFC). In this paper, a new algorithm is proposed to detect and classify the fault and identify the fault position in a transmission line with respect to a FACTS device placed in the midpoint of the transmission line. Discrete wavelet transformation and wavelet entropy calculations are used to analyze during fault current and voltage signals of the compensated transmission line. The proposed algorithm is very simple and accurate in fault detection and classification. A variety of fault cases and simulation results are introduced to show the effectiveness of such algorithm.

STATCOM modeling impacts on performance evaluation of distance protection of transmission lines

AbstractIn this paper, the impact of STATCOM on the apparent impedance seen by conventional distance relay protecting a transmission line is investigated. Analytical results are presented, and verified by detailed simulations. It is shown that the implications of applying STATCOM on distance relay are highly dependent on the sophisticated modeling of STATCOM especially its control system considering practical constraints. Accurate modeling of the distance relay, particularly the analog input signals are also important in extracting reliable results. Practical constraints of the STATCOM are modeled in full details. It is demonstrated that when the STATCOM's limits are modeled in detail, i.e., the STATCOM is not considered an ideal reactive‐power source the STATCOM's impact on the performance of distance protection is less severe than in the case where limits are ignored and thus ideal controllers are applied. This is a remarkable point for the utilities as not to overestimate the severity of the impact of STATCOM on conventional distance protection of transmission lines. Six different phase‐to‐phase and phase‐to‐ground measuring units of the distance relay are simulated to resemble the behavior of the relay. Different power system operating conditions, STATCOM control system settings and fault scenarios are investigated. The STATCOM effects on distance relay tripping characteristics are also analyzed. Copyright © 2010 John Wiley & Sons, Ltd.