Relay For Transmission Line Protection Research Articles

Enhanced sensitive phase alpha plane scheme against high resistance ground faults

Abstract Phase-based Alpha (α) Plane Relaying (APR) scheme has numerous advantages over the Current Differential Relay (CDR) for transmission line protection. Since the large Restraining Region (RR) in the APR makes high security against CT saturation, channel delay, line charging current and synchronization error. However, the APR loses its sensitivity for high resistance ground faults, especially single line to ground faults under outfeed conditions. Also, losing its dependability under close-in low resistance three-phase faults. Thereby, the sequence-based APR provides enhanced sensitivity with the cost of computational burden and complexity. Hence, in this paper, the concept of the average value (I Avg) of both end instantaneous currents is used as an auxiliary logic. In which, the polarity of I Avg is incorporated as an add-on logic to the conventional APR to confirm high resistance internal faults. Thereby, the requirement of sequence components can be avoided (negative and zero). To validate the proposed auxiliary logic, it is tested for the WSCC (Western System Coordinating Council) 9-bus, 110 kV, 50 Hz. System. The simulated results under various fault cases found authenticated results. In addition, the comparative assessment and validation with real-world data reveal the enhanced sensitivity of the proposed logic under high-resistance ground faults.

Analysis of the Impact of a Modular SSSC on the Operation of Transmission Line Protection Relays using a Hardware-In-the-Loop Configuration

This paper evaluates the impact of a modular Static Synchronous Series Compensator (m-SSSC) on the operation of communication-assisted line distance and differential protection relays. The m-SSSC system incorporates an over-current protection feature to trigger the bypass mode of operation during grid faults. A case study is analyzed for a 220 kV transmission line and an m-SSSC with a reactive power rating of 80 MVAr per phase using a Hardware-In-the-Loop configuration. The obtained results show the impact of the m-SSSC system on the distance protection operation during some cases of high resistive faults. The differential protection operation was not affected by the mSSSC.

The Effect of Wind Power Generation on Distance Relay Performance

Wind Power Plants utilize induction generators to generate electrical power. This type of generator produces less short circuit current than synchronous generators; hence it may affect the operation of transmission line protection relays. This research aims to analyze the effect of a large-scale wind power plant connected to the transmission line on the performance of the distance relays. The study utilizes a simulation method using Digsilent Powerfactory on IEEE 5 bus test system. The performance of the distance relays is compared between the original system, and the system in one of its generators is replaced with a wind turbine generator. The simulations are carried out for 3-phase faults that consist of bolted short circuits, 1-ohm fault resistance and 10-ohm fault resistances. The results show that the relays performances in zone 1 are the same for all types of generations. For zones 2 and 3, depending on the relay's position, the reaches may increase or decrease when the generator is replaced by wind power. The increasing reach of the relays is due to the dropping of infeed effect felt by the relay after installation of wind power. While the decreasing reaches of some relays because they see less fault current from the wind generation. The other relays do not experience any changes. Fault resistances cause all relays to experience reduced reach.

Modeling and Simulation of Mho Type Distance Relay for High Voltage Transmission Line Protection

Abstract-This paper describes the opportunity of implementing a model of a Mho type distance relay with three zones by using MATLAB/SIMULINK package. SimPowerSystem toolbox was used for detailed modeling of distance relay, transmission line and fault simulation. The proposed model was verified under different tests, such as fault detection which includes single line to ground (SLG) fault, double line fault (LL), double line to ground fault (LLG) and three phase fault, all types of faults were applied at different locations to test this model. The results show that the relay operates correctly under different locations for each fault type. Keywords- Distance relay, Single line to ground fault (L-G), Double line to ground (L-L-G), Line to Line fault (L-L), Three phase fault (L-L-L), MATLAB/SIMULINK.

A New Approach to Transmission Line Pilot Protection in the Presence of Inverter-Interfaced Distributed Generators

In recent decades, the penetration of inverter-interfaced distributed generators (IIDGs) in power systems has increased significantly due to the environmental and economic benefits. The increasing participation of IIDGs and the developments of power electronic technologies have raised the possibility of controlling the power injected by IIDGs for regulating the voltage level, especially during short-circuit fault conditions, following the regional grid codes. When a short-circuit fault occurs on the transmission line connected to the IIDGs bus, a dramatic voltage drop occurs. In this situation, the IIDG injects the reactive power fast that disrupts the performance of the distance relay as a result of which the operation of the relay in different operational conditions may either over reach or under reach. In this article, a comprehensive analysis is accomplished regarding the errors imposed on the estimated impedance of the distance relay, due to the voltage control of IIDGs, in single and double-circuit transmission lines. Then, an impedance-based pilot protection method is proposed to enhance the performance of the transmission line protection relays affected by the reactive power injected by the IIDGs.

A Deep Learning-Based Cyberattack Detection System for Transmission Protective Relays

The digitalization of power systems over the past decade has made the cybersecurity of substations a top priority for regulatory agencies and utilities. Proprietary communication protocols are being increasingly replaced by standardized and interoperable protocols providing utility operators with remote access and control capabilities at the expense of growing cyberattack risks. In particular, the potential of supply chain cyberattacks is on the rise in industrial control systems. In this environment, there is a pressing need for the development of cyberattack detection systems for substations and in particular protective relays, a critical component of substation operation. This article presents a deep learning-based cyberattack detection system for transmission line protective relays. The proposed cyberattack detection system is first trained with current and voltage measurements representing various types of faults on the transmission lines. The cyberattack detection system is then employed to detect current and voltage measurements that are maliciously injected by an attacker to trigger the transmission line protective relays. The proposed cyberattack detection system is evaluated under a variety of cyberattack scenarios. The results demonstrate that a universal architecture can be designed for the deep learning-based cyberattack detection systems in substations.

A Novel Methodology for the Determination of Impulse Response Coefficients Applied to Transmission Line Protection Relays

Impulse Response Coefficients (IRC) of digital filters is an imperative step in the development of transmission line protection relay algorithms. Traditionally, Fourier-based filters are used in real applications, where IRC are fixed values of sine and cosine functions with a data window of one or more cycles. Based on state-of-the-art, Mother Wavelet coefficients used in Multiresolution Analysis, and Structuring Element coefficients used in Mathematical Morphology are usually proposed to develop protection algorithms. However, the proper choice of these coefficients is based on empirical process of trial and error. This paper proposes a novel methodology for optimally determining coefficients that depend on the waveform structure analyzed, which is determined using variance as the metric. Assessment of methodology for three case studies considering requirements of relay manufactures (response time, design, harmonic attenuation and other) is presented. The first assessment is to extract coefficients useful for distinguishing among non-fault conditions, harmonics, and arcing faults. The second one is to extract coefficients to filter harmonic components. The assessment is carried out considering different data windows and sampling rates. Test results highlight the efficiency of the model to determine specific coefficients for each case study analyzed. Interestingly, results also showed that the discovered coefficients can be used in another filtering technique. Thus, the third case study involves developing two fault classifiers, which are developed using mathematical morphology where the structuring elements used correspond to the coefficient vectors determined through the proposed methodology. There is a notable paucity of scientific literature focusing on this topic. Therefore, there are several important areas where this study makes an original contribution regarding protection relays.

Modelling and Simulation of Mho Type Distance Relay for High Voltage Transmission Line Protection Using MATLAB Software

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.

A new approach of Mho distance relay for Transmission line protection

The protection of transmission line is one of the important requirements of the modern power system network to protect the equipment and persons work on it. distance relay is one of the relays used to protect the transmission line where the input to the fuzzy based distance relay are the resistance and reactance of transmission line from relay to the fault location. These were calculated from the measured voltage and current. Mho type distance relay is proposed by using fuzzy logic methodology to protect the transmission line and to defeat under and over-reach problems. MATLAB-Simulink is used to model the relay and the test network, where the fault type is detected and four zones of fault location are provided, the trip signal is delayed according to the zone number. Also the (R-JX) plain is used to show the zone of fault in a simplified manner.

Induced Lightning Stroke Identification on Protection Relays

It is well known that lightning strokes produce mal-operation of transmission line protection relays. Where, protection devices cannot identify correctly between lightning stroke that generates or not permanent faults. Thus, when a flash produces a permanent fault, the protection relay sends a trip order, and the Transmission Line (TL) is disconnected correctly. However, when a lightning stroke does not produce a permanent fault, the protection devices also send the trip order, and the TL is disconnected unnecessary. In this context, these phenomena can produce unnecessary electric power outages, producing damage for the society and economic. Therefore, it is necessary to correctly identify between these lightning stroke signals. Besides that, direct lightning strokes, which hit directly on TLs or transmission towers, have usually been analyzed. However, induced lightning strokes, which hit on ground, have not been considered in previous analyzed. In this paper, in order to identify these induced lightning strokes, an algorithm based on a deterministic focus is proposed.

Classification of lightning stroke on transmission line using multi-resolution analysis and machine learning

One of most important elements of Electric Power Systems (EPS) is the transmission line (TL), which is permanently under adverse conditions especially lightning strokes. At the moment, those phenomena have been the root cause of short circuits and the most important cause of mal-operation of transmission line protection relays. Thus, this paper develops the classification of lightning transient signals with and without fault. Multi-resolution analysis (MRA) is used to analyze those signals considering five mother wavelets and different decomposition levels of three phase voltages. In this manner, Spectral Energy and Machine Learning as Artificial Neural Network, K-Nearest Neighbors and Support Vector Machine are employed to classify those signals. On the other hand, the developed work in this paper analyzes most important parameters of lightning strokes, which are essentials in producing conditions with and without fault. Results show that the methodology presents an acceptable performance.

Modeling and testing of multi-resolution morphological gradient distance relay algorithm

This paper describes modeling and testing of a digital distance relay for transmission line protection using MATLAB/SIMULINK. ATP is used for detailed modeling of a power system network and fault simulation. SIMULINK is used to implement multi-resolution morphological gradient (MMG) relaying algorithm. MMG modeling is an interactive simulation environment for relaying algorithm design and evaluation. The basic principles of MMG relaying algorithm and some related algorithms such as tripping and fault location scheme are also described in this paper. Test results show that MMG relaying algorithm can detect and define fault location accurately within 1 milli-second.

Dynamic performance of the power differential relay for transmission line protection

Power differential relay was proposed recently as a practical relaying scheme for transmission systems. In this paper, the dynamic behaviour of the power differential relay is thoroughly investigated. These investigations are important to evaluate the overall performance of such relaying functions. For this target, a detailed simulation of a typical transmission system was developed via the MATLAB/SIMULINK package using detailed modeling for each power system element. Both stable and unstable power swings are considered. Moreover, single machine-infinite bus and double machine system operations are considered for all possible faulty and non-faulty conditions. All applied test results confirm the superiority of the power differential relay as an ideal candidate for transmission system protection applications.

Digital relay software reliability allocation optimisation for transmission line protection

Traditional methods for performance assessment of transmission line protective relays by hardware inspection and testing seem to be inadequate in case of contemporary digital relays. This is because about 80% of the engineering design content of digital relays is in the software area. Therefore, software reliability naturally emerges as an area of utmost interest. Recently, some digital relay algorithms have been proposed based on frequency domain using wavelet-neuro-fuzzy approaches for transmission line protection. In this paper, a software reliability allocation model is developed for the performance evaluation of such a digital relay for detection, classification and location of transmission line faults. Keeping the relative importance of different functions of a multi-functional digital relay, the software reliability allocation has been implemented using the analytical hierarchy process. The results contained in this paper validate the efficacy of the proposed method for optimising the utility of frequency domain-based digital relay for real-time implementation.

Software reliability allocation of digital relay for transmission line protection using a combined system hierarchy and fault tree approach

Digital relay is a special purpose signal processing unit in which the samples of physical parameters such as current, voltage and other quantities are taken. With the proliferation of computer technology in terms of computational ability as well as reliability, computers are being used for such digital signal processing purposes. As far as computer hardware is concerned, it has been growing steadily in terms of power and reliability. Since power plant technology is now globally switching over to such computer-based relaying, software reliability naturally emerges as an area of prime importance. Recently, some computer-based digital relay algorithms have been proposed based on frequency-domain analysis using wavelet-neuro-fuzzy techniques for transmission line faults. A software reliability allocation scheme is devised for the performance evaluation of a multi-functional, multi-user digital relay that does detection, classification and location of transmission line faults.

Microcontroller-Based Numerical Quadrilateral Relay for the Transmission Line Protection

This article presents an Intel 8097 microcontroller-based numerical quadrilateral distance relay for transmission line protection. The numerical filtering algorithm used for the extraction of fundamental frequency components from the corrupted post fault relaying signals is based on Block pulse functions. The microcontroller computes the real and reactive components (R and X) of the apparent impedance of the line as seen by the relay by using the real and imaginary components of the fundamental frequency voltage and current phasors. Using the computed values of R and X, the microcontroller examines whether the fault point lies within the quadrilateral relay's protective zone or not. If the fault point lies in the protective zone of the relay, the microcontroller issues a trip signal to the circuit breaker. The relay is successfully tested for a number of different three step quadrilateral characteristics and the results are obtained. The proposed relay is reliable, flexible, accurate and fast.

Modular Neural Network-Based Directional Relay for Transmission Line Protection

This letter proposes the application of a modular neural network as a mechanism to discriminate the direction of faults for transmission line protection. The modular neural network approach solves a relatively complex problem by decomposing it into simpler subtasks that are easier to manage and then assembles the solution from the results of the subtasks. In addition to the obvious advantages of a neural network as a fault classifier, incorporation of modularity to the network structure provides more important positive attributes like model complexity reduction, better learning capability, etc. The modular neural network concept has been utilized successfully to develop a directional relay algorithm for a transmission system and subsequently implemented on a DSP TMS320F243 EVM-board.

ANN applications in fault locators

Recent developments indicate that Artificial Neural Networks (ANNs) may be appropriate for assisting dispatchers in operating electric power systems. The fault location algorithm being a key element in the digital relay for power transmission line protection, this paper discusses the potential applicability of ANN techniques for determination of fault location and fault resistance on EHV transmission lines with remote end in-feed. Most of the applications make use of the conventional Multi Layer Perceptron (MLP) model based on back propagation algorithm. However, this model suffers from the problem of slow learning rate. A modified ANN learning technique for fault location and fault resistance determination is presented in this paper. A reasonably small NN is built automatically without guessing the size, depth, and connectivity pattern of the NN in advance. Results of study on a 400 kV transmission line are presented for illustration purposes. Performance of the modified ANN is compared with the analytical algorithms and conventional MLP algorithm for different combinations of pre-fault loading condition, fault resistance and fault location. The results are found to be encouraging.

High-speed transmission line relaying using artificial neural networks

A novel feedforward neural network that indicates whether a fault is within or outside the protection zone (fault indicator) of a transmission line is presented. The same technique has been extended to locate the distance of the fault (fault locator). The proposed scheme utilizes the frequency spectrum of the voltages and currents to make a decision. Data obtained from the electromagnetic transient program for single-line-to-ground faults and three-phase faults have been tested and the results are found to be accurate. Using this neural network the relaying decision is obtained within a cycle after the fault inception. The performance of the trained neural network shows promise and has the potential for implementation in a digital relay for transmission line protection.

Proposed statistical performance measures for microprocessor-based transmission-line protective relays. I. Explanation of the statistics

The paper presents practical calculations and novel techniques for collecting performance data from protective relays. The methods are focused on, but not limited to, microprocessor-based transmission line relaying systems. Standard definitions are presented for availability, dependability, security, hardware MTBF, relaying MTBF, repair time, and other measures of interest for specific relay types. The paper explains the novel concept of exposures, the key to a standardized security measure. With these standard measures, relay users will be able to compile the first consistent industry-wide data base for relay performance assessment.