Saturday, March 12, 2011

ABSTRACT, Protection on Transmission Overhead Line Used Distance Relay

   1.   Jafarian, P., Sanaye-Pasand, M., 2011. Weighted least error squares based variable window phasor estimator for distance relaying application. Iet Generation Transmission & Distribution 5, 298-306.
Abstract: This study presents an adaptive data window algorithm for fast and accurate signal phasor estimation. The proposed approach is based on weighted least error squares algorithm as well as variable data window estimation technique. An adaptive model is used for the input signal during the two stages. The first stage is considered to accelerate the relay first zone operation. This is done through applying a forgetting factor in the cost function computation, by which the effect of older samples on the estimation is reduced to decrease the initial inertia of the phasor estimator. The second stage starts one cycle after occurrence of the fault. This algorithm is used to improve the estimation accuracy and helps to obtain better estimation for the fault location. To verify the performance of the proposed algorithm, various simulation studies are carried out. The algorithm is also evaluated using some field data recorded from a high-voltage transmission system. The obtained results confirm accurate, fast and reliable response of the proposed algorithm. It not only accelerates the relay operation but also improves the digital filters' capability of reducing the estimation error because of power system frequency deviation, harmonics, inter-harmonics and decaying dc component

   2.   Pang, C.Z., Kezunovic, M., 2010. Fast Distance Relay Scheme for Detecting Symmetrical Fault During Power Swing. Ieee Transactions on Power Delivery 25, 2205-2212.

Abstract: The power swing caused by various disturbances will affect distance relay behavior and may result in relay misoperation. This paper provides a fast detection scheme for symmetrical fault during power swing for distance relay, which is based on extracting the high-frequency component energy of forward and backward traveling waves induced by faults. The multiresolution analysis based on wavelet transform has the ability to decompose the analyzed signals into different frequency bands. The selection of mother wavelet and the number of levels of wavelet transform are carefully studied. The fault can be identified by feature extracting from the d1 component of Daubechies-8 (Db8) wavelet transform. The proposed approach is verified by using the IEEE reference model implemented by using the Alternate Transients Program and the test results have been presented in this paper. This proposed method can be used for distance relay operation blocking or monitoring
   3.   Roy, D.S., Anil, A., Mohanta, D.K., Panda, A.K., 2010. Well-being Analysis of Safety Critical Software: A Case Study for Computer Relaying. Electric Power Components and Systems 38, 1299-1316.

Abstract: Assessment of software reliability has emerged as an area of utmost importance in recent times with the proliferation of software-based systems. Conventional software reliability assessment is done by applying software models that incorporate the unfortunate drawback of requiring previous failure data to formulate the model based on statistical methodologies. But highly dependable software systems used for safety-critical applications, such as computer relays for power system transmission line protection, produce little failure data. This article presents a methodology using statistics of extremes to embark upon software success estimation. The estimate so obtained is an indicator analogous to the conventional reliability index. This estimated reliability is further employed for assessing software's health more effectively by means of well-being analysis. The most significant contribution of this article is to compute the software well-being indices for healthy, marginal, and risky states. A case study for software used in computer relaying of power system transmission line protection validates the efficacy of the proposed methodology, especially for safety-critical applications
   4.   Abu Bakar, A., Yatim, F.M., Yusof, S., Othman, M.R., 2010. Analysis of overload conditions in distance relay under severe system contingencies. International Journal of Electrical Power & Energy Systems 32, 345-350.

Abstract: Distance relay protection is widely used worldwide for protection scheme on high voltage transmission lines. This protection tends to be prone to load encroachment condition causing possible undesired tripping condition. Investigations of two system disturbances that occurred in TNB's (Tenaga Nasional Berhad) Grid in the year 2003 and 2005 have clearly revealed the occurrence of load encroachment condition following line overloads after large number of line tripping. Examination of the impedance locus trajectory during the overload events have enabled a distinction be made between power swing and load encroachment phenomena. This paper presents the analysis and findings of the investigation of the load encroachment phenomena of the two events, including other related transmission line contingencies. (C) 2009 Elsevier Ltd. All rights reserved
   5.   Siozinys, V., 2010. Transmission Line Fault Distance Measurement based on Time Difference between Travelling Wave Reflection and Refraction. Elektronika Ir Elektrotechnika 25-28.
Abstract: V. Siozinys. Transmission Line Fault Distance Measurement based on Time Difference between Travelling Wave Reflection and Refraction H Electronics and Electrical Engineering. - Kaunas: Technologija, 2010. - No. 2(98). - P. 25-28. The relay protection principles based on travelling wave are observed. Transmission line fault distance measurement algorithm based on time difference between travelling wave reflection and refraction is proposed. An algorithm, its mathematical prove, modelling results and errors are presented in article. The simple scheme calculation example is presented to describe fault location algorithm behaviour. Transmission line model with 4 lines which length is from 200 to 400 meters is used to represent algorithm. The distance to fault location calculated error is in range of 1-3%. III. 3, bibl. 4 (in English; summaries in English, Russian and Lithuanian)
   6.   Ekici, S., Yildirim, S., Poyraz, M., 2009. A Pattern Recognition Application for Distance Protection. Journal of the Faculty of Engineering and Architecture of Gazi University 24, 51-61.
Abstract: In this paper, a method based on Support Vector Machines (SVM) as pattern classifier is presented for distance protection operation. The proposed method generates an output by determining faults occurred at different location of power transmission line for relay operation. The approach utilizes three-phase current and voltage information. The current and voltage information which are used in training and testing of SVM are obtained from a transmission line simulation which is performed by Alternative Transient Program (ATP). In the implemented digital relay application, it is shown that SVM classifies faults occurred on transmission line with very high performance level
   7.   Dambhare, S., Soman, S.A., Chandorkar, M.C., 2009. Adaptive Current Differential Protection Schemes for Transmission-Line Protection. Ieee Transactions on Power Delivery 24, 1832-1841.
Abstract: Throughout the history of power system protection, researchers have strived to increase sensitivity and speed of apparatus protection systems without compromising security. With the significant technological advances in wide-area measurement systems, for transmission system protection, current differential protection scheme outscores alternatives like overcurrent and distance protection schemes. Therefore, in this paper, we address this challenge by proposing a methodology for adaptive control of the restraining region in a current differential plane. First an error analysis of conventional phasor approach for current differential protection is provided using the concept of dynamic phasor. Subsequently, we extend the methodology for protection of series compensated transmission lines. Finally, we also evaluate the speed versus accuracy conflict using phasorlets. Electromagnetic Transient Program simulations are used to substantiate the claims. The results demonstrate the utility of the proposed approach
   8.   Valsan, S.P., Swarup, K.S., 2009. Wavelet transform based digital protection for transmission lines. International Journal of Electrical Power & Energy Systems 31, 379-388.
Abstract: This paper presents a high speed, computationally efficient scheme for protection of transmission lines. The relay logic consists of three parts: directional protection, fault classification and fault location. Wavelet transform is used for extracting information from the fault transients and only the first level high frequency details of the voltages and currents are used. Proposed protection logic compares the directional signals from both terminals to discriminate between faults inside and outside the zone of interest. Fault classification is achieved using local terminal current information. An estimate of the location of the faults is obtained utilizing single faulted phase current information from both terminals. The logic is deterministic and can work reliably in the presence of fault resistance, load variation and CT saturation. The validity of the proposed logic was exhaustively tested by simulating various types of faults on a four bus meshed system modeled in EMTP/ATP. (C) 2009 Elsevier Ltd. All rights reserved
   9.   Reddy, M.J.B., Mohanta, D.K., 2008. Performance Evaluation of an Adaptive-Network-Based Fuzzy Inference System Approach for Location of Faults on Transmission Lines Using Monte Carlo Simulation. Ieee Transactions on Fuzzy Systems 16, 909-919.

Abstract: This paper employs a wavelet multiresolution analysis (MRA) along with the adaptive-network-based fuzzy inference system to overcome the difficulties associated with conventional voltage- and current-based measurements for transmission-line fault location algorithms, due to the effect of factors such as fault inception angle, fault impedance, and fault distance. This proposed approach is different from conventional algorithms that are based on deterministic computations on a well-defined model to be protected, employing wavelet transform together with intelligent computational techniques, such as the fuzzy inference system 9 adaptive neurofuzzy inference system (ANFIS), and artificial neural network (ANN) in order to incorporate expert evaluation so as to extract important features from wavelet MRA coefficients for obtaining coherent conclusions regarding fault location. A comparative study establishes that the ANFIS approach has superiority over ANN- and FIS-based approaches for the location of line faults. In addition, the efficacy of the ANFIS is validated through the Monte Carlo simulation for incorporating the stochastic nature of fault occurrence in practical systems. Thus, this ANFIS-based digital relay can be used as an effective tool for real-time digital relaying purposes
10.   Gerin-Lajoie, L., 2009. A MHO distance relay device in EMTPWorks. Electric Power Systems Research 79, 484-491.

Abstract: Distance relays are widely used for protection of transmission lines. Usually, the nonlinear nature of an arcing fault requires that a time model be implemented to determine if the relay detects or not this fault condition. Moreover, the mutual effect of line conductors for single or multiphase faults requires that all three phases of the relay be modelized. This paper describes in detail a first generic MHO distance relay in EMTPWorks based on three separate single-phase impedance vectors. Cosine-sine filters are used to perform the phasor representation of the fundamental current and voltage computed over a 50/60 Hz sliding time window, Validation of the measured impedance function of the model is compared with the real apparent impedance of the network. This paper also discusses logical operations to initiate the opening of line breakers. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved
11.   Eissa, M.M., 2009. New principle for transmission line protection using phase portrait plane. Iet Generation Transmission & Distribution 3, 49-56.
Abstract: Phase portraits are a powerful mathematical model for describing oriented textures. An isotangent-based approach in a phase portrait is introduced to discriminate between internal and external faults. The scheme described is new and is a different approach to the problem of relaying ground faults on transmission lines. The geometrical theory of differential equations is used to drive a symbol set on the basis of the visual appearance of phase portraits. The 'phase portrait' of the instantaneous rate of change of current against voltage gives valuable information on the transient and stability characteristics of system configuration with high fault resistance and shunt susceptance of the transmission lines. Hundred percent of the protected zone is successfully discriminated rather than the external zone. An additional parameter that is considered, which is sometimes neglected in protection studies, is the shunt susceptance of the transmission lines
12.   Ravikumar, B., Thukaram, D., Khincha, H.P., 2009. An Approach Using Support Vector Machines for Distance Relay Coordination in Transmission System. Ieee Transactions on Power Delivery 24, 79-88.
Abstract: This paper presents transmission system distance relaying co-ordination using detailed simulation studies of the apparent impedance loci as seen from the relaying location considering various operating conditions including fault resistance. Support vector machines (SVMs) are used as a pattern classifier for obtaining distance relay co-ordination. The scheme utilizes the apparent impedance values observed during fault as inputs. An improved performance with the use of SVMs, keeping the reach when faced with different fault conditions as well as system power flow changes are illustrated with an equivalent 246 bus system of practical Indian Southern grid
13.   Bhalja, B., Maheshwari, R.P., 2008. Protection of transmission line paralleled along the same right-of-way. Electric Power Components and Systems 36, 239-249.
Abstract: This article presents a novel scheme for the protection of parallel transmission line paralleled along the same right-of-way using wavelet packet transform (WPT). The proposed scheme is based on the difference between the absolute of the additions of wavelet coefficients computed using WPT at the third level with the help of db4 wavelet function. This concept has been applied to the corresponding phases of both the lines in parallel. The WPT is used to capture important features of the decomposed signal that are sensitive to infeed current and mutual coupling and provides stability against in-zone faults. The wavelet packets are highly sensitive toward high-resistance faults and a computationally more flexible way to conduct signal discrimination than wavelet transforms-based methods. The proposed method completely avoids voltage signal used in conventional relays and also ignores the requirement of communication channel. The relay provides reliability and selectivity for discriminating cross-country faults and internal faults and remains stable against external faults. The proposed scheme has been tested under different fault and system conditions with varying fault resistance between 0-200 Omega . A series of tests using test signals generated by Power System Computer Aided Design/Electro-magnetic Transients in DC Systems (PSCAD/EMTDC) for a 400-kV parallel transmission line have proven the accuracy and effectiveness of the proposed scheme
14.   Rosas-Ortiz, G., Sidhu, T.S., 2007. High-speed backup scheme for zone 2 of non-pilot distance relays. Iet Generation Transmission & Distribution 1, 938-947.
Abstract: Distance relays use time-stepped protection zones for coordination purposes. The time delay introduced by zone 2 relays limits the use of these devices for extra high voltage (EHV) applications, since the fast fault clearance requirement is not achieved. Normally, transmission lines are protected by means of intercommunicated protection schemes making use of a dedicated channel in order to overcome that delay; however, this channel is also prone to failure. Hence, it could be really advantageous to provide the line with fast protection coverage without making use of communication channels if a secure enough protection algorithm were developed for this specific purpose. An algorithm that is able to detect remote breaker operation and thus to accelerate the time-delayed zone 2 trip of local relay by monitoring changes in two proposed signals is presented. The algorithm performs adequately in two- and three-terminal lines as it is shown by computer simulation results. It is proposed that this algorithm can be used as a fast backup scheme to protect transmission lines in case main communication channel degrades, fails or is not available
15.   Yu, C.S., 2007. Removal of the decaying DC effects in distance protection by simultaneously considering the voltage and current waveforms. Journal of the Chinese Institute of Engineers 30, 1047-1057.

Abstract: Distance relays are widely used for transmission line protection. The dependability of distance relays can be improved by obtaining the accurate apparent impedance as fast as possible. In conventional design, the fault voltage and current are filtered separately to remove the decaying dc components and obtain accurate fundamental phasors, respectively. However, the main task of distance protection is not to obtain the accurate voltage or current fundamental phasor, but to obtain the accurate apparent impedance. This paper proposes a new technique to simultaneously consider voltage and current waveforms and remove the decaying dc component between them. By the proposed technique, although the decaying dc components in voltage and current are not removed, the decaying dc effect in apparent impedance is removed. In comparison with the existing algorithms, the proposed technique is simpler and easier to implement. The simulation results demonstrate the effectiveness and accuracy of the proposed technique
16.   Shrivastava, K., Vishwakarma, D.N., 2007. Microcontroller-based numerical quadrilateral relay for the transmission line protection. Electric Power Components and Systems 35, 1301-1315.
Abstract: 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
17.   So, K.H., Heo, J.Y., Kim, C.H., Aggarwal, R.K., Song, K.B., 2007. Out-of-step detection algorithm using frequency deviation of voltage. Iet Generation Transmission & Distribution 1, 119-126.

Abstract: Protection against transient instability and a consequent out-of-step condition is a major concern for the utility industry. An unstable system may cause serious damage to system elements such as generators and transmission lines, therefore out-of-step detection is essential to operate a system safely. The traditional out-of-step relays detect out-of-step conditions by using distance relays and timers. However, such a relay monitors only apparent impedance which is an indirect function of generator angle, and the relay cannot cope with the out-of-step situation for the more severe instability situation of very fast power swings which can also cause damage to transmission lines if not detected fast enough, as is the case with conventional detection techniques. Digital filters based on discrete Fourier transforms are used to calculate the frequency of a sinusoidal voltage, and then the generator angle is estimated using the deviation of the calculated frequency component of the voltage. The proposed out-of-step detection algorithm is based on the assessment of transient stability using the equal-area criterion. It is verified and tested by using ATP/EMTP MODELS, and the simulation results show that the out-of-step conditions are detected accurately employing the proposed algorithm
18.   Sanaye-Pasand, M., Pour, V.S., 2007. A combined digital distance relaying algorithm and its performance evaluation. Electric Power Components and Systems 35, 1255-1270.

Abstract: Power system protective relays protect electric systems against system faults and abnormalities. Due to increasing advantages of digital relay algorithms, nowadays modern power system protective relays are mostly microprocessor based. Digital based algorithms are used in these relays to implement different relaying schemes. In this article, a combined method using a combination of both differential equation and least square error algorithms is presented The proposed method is explained analytically and modeled appropriately. Simulation results are presented to illustrate effectiveness of this combined algorithm for transmission line distance protection. Performance of the proposed algorithm was also investigated using some recorded fault data. Efficiency and reliability of this method could be perceived by the obtained results
19.   Bhalja, B., Maheshwari, R.P., 2007. Percentage differential protection of double-circuit line using wavelet transform. Electric Power Components and Systems 35, 945-954.

Abstract: This article presents development of a new percentage differential protection scheme for double- circuit transmission line using wavelet transform (WT). The work presented addresses the problems encountered by conventional distance relays when protecting double- circuit transmission lines sharing the same right of way. By the use of powerful analyzing and decomposing features of WT, a new technique is presented that takes care of the problems faced by pilot independent distance relay. The suggested technique depends on the six line currents of the two parallel lines at each end. The idea of the protection algorithm is based on the percentage of the difference of the two line current of each corresponding phase at each terminal. The measured six line currents at the relay location are decomposed into three levels of decomposition using the db4 mother wavelet. The summation of third level approximation coefficients are used as bias current whereas third level detailed coefficients are used as differential current. The proposed method eliminates many of the problems associated with double- circuit lines, such as high fault resistance, cross- country fault, mutual coupling effects, remote infeed, and avoids the problem of single- end supply. The stability of the relay under varied system configurations and operating conditions is examined. The relay algorithm is tested for various probable fault inception angles and loading conditions and with varying fault resistance between 0-150 ohms. The proposed wavelet based scheme provides encouraging results for different fault and system conditions. Relaying signals under different fault conditions were obtained by simulating the system using PSCAD/EMTDC
20.   Bhalja, B., Maheshwari, R.P., 2007. An adaptive distance relaying scheme using radial basis function neural network. Electric Power Components and Systems 35, 245-259.
Abstract: The distance calculation performed by a distance relay is incorrect due to ground fault resistance, prefault system conditions, mutual coupling effect and shunt capacitance influences. The problem is more serious keeping in view that all relay settings are made based on some compromise. The work presented in this article addresses the problems encountered by conventional pilot independent distance relay when protecting two terminal transmission lines. The key feature is that it presents the detailed analysis of the apparent impedance as seen from the relaying point taking into account the effects of transmission line parameter uncertainties, shunt capacitance influences and variations in the system external to the protected line. These results can be used for estimation of correct impedance of transmission line, hence taking relaying decisions. Based on the results of extensive computer simulation of the infeed/outfeed, fault resistance and shunt capacitance effects on the relay characteristics, an adaptive distance relaying scheme is proposed for such lines using a radial basis function neural network (RBFNN), which provides a more efficient approach for training, computation, adaptation, and tripping than the conventional feed forward network using back propagation algorithm (BPNN). The proposed adaptive protection scheme is tested for a single line to ground fault, but for varying fault locations, fault resistances, fault inception angles, and different source impedance ratio too. At the end, comparison of conventional feed forward network using back propagation algorithm with radial basis function classifier is also given, which clearly indicates improvement. Hence, the selectivity of the protection system is increased, as is the power system reliability
21.   Zhang, N., Kezunovic, M., 2007. A real time fault analysis tool for monitoring operation of transmission line protective relay. Electric Power Systems Research 77, 361-370.
Abstract: This paper proposes an integrated real time fault analysis tool for transmission line. The two primary techniques used in the fault analysis tool, fuzzy adaptive resonance theory (ART) neural network and synchronized sampling, can offer accurate fault detection, classification, internal/external fault differentiation, and fault location. The paper makes several extensions of the two techniques so that they can fit well in the realistic situations. The hardware configuration and software implementation are proposed in the paper. A comprehensive evaluation study is implemented to compare the proposed fault analysis tool with the traditional distance relay. Simulation results indicate that the integration exemplifies the advantages of both techniques and that the integrated solution has much better performance in different system conditions compared to distance relay. Both dependability and security of transmission line protection system are improved by using the proposed tool. (C) 2006 Elsevier B.V. All rights reserved
22.   Erenturk, K., 2005. A new digital protective relay based on fuzzy logic and value estimation. Iranian Journal of Science and Technology Transaction A-Science 29, 267-276.
Abstract: In this paper, design and application of a new digital protective relay based on fuzzy logic and value estimation to a radial power system protection was presented. A novel approach based on value estimation was investigated for the proposed fuzzy logic based protective relay. In addition to the theoretical aspect of fuzzy logic, mathematical definition of value estimation, detection and measurement of faulty current, determination of its duration, decision mechanism and detailed system architecture were also introduced. ne examined technique based on fuzzy logic and value estimation to control the protection action of the protective relay was intended to improve the performance of a conventional protective relay control for human safety and system reliability with the use of a fuzzy logic controller. The difference between estimated and sampled values was used to form the rule base. Proposed relay architecture was used as a detector and was developed to predict faults and to protect particular sections of a designed prototype radial power system at an early stage. Performance analysis was made, and related results and discussion were given
23.   Kim, I.D., Aggarwal, R.K., 2006. A study on the on-line measurement of transmission line impedances for improved relaying protection. International Journal of Electrical Power & Energy Systems 28, 359-366.

Abstract: This paper proposed an on-line measurement of transmission line impedance in order to improve the accuracy of distance relays and analysis of power system. Distance relays are generally set by the estimated impedance of the protected lines, which involves a certain amount of error in itself. Especially, the zero sequence impedance has more erroneous terms associated with mutual effects in parallel line as well as uncertainty of ground return path. The proposed method is measuring impedance either during normal operation or during faults, and can be applied on-line correction of the setting value of distance relays. This on-line measured positive impedance may be used to monitor the transmission line condition during operation and more accurate impedance data may also improve performance of power system analysis. For verification of the proposed method, several simulations have been executed and shown satisfactory results. (C) 2006 Published by Elsevier Ltd
24.   Sidhu, T.S., Khederzadeh, M., 2006. Series compensated line protection enhancement by modified pilot relaying schemes. Ieee Transactions on Power Delivery 21, 1191-1198.

Abstract: In this paper, a comprehensive analysis of the impact of series capacitor on the performance of communication-aided distance protection schemes of transmission lines is presented. It is shown that not only the series capacitor and its overvoltage protection affect the distance protection of its line, but also the adjacent lines would experience protection problems. Mitigation of this problem is proposed by using new communication-aided schemes. The proposed schemes use the information available at the substation to inhibit relay malfunctions. The performance of the techniques is studied for different series capacitor locations in the transmission line. Real Time Digital Simulator (RTDS) and four sophisticated commercial relays are used for testing. The results verify the impact of series capacitor on the conventional communication-aided schemes and also the effectiveness of the proposed methods
25.   Chen, C.S., Liu, C.W., Jiang, J.A., 2006. Application of combined adaptive fourier filtering technique and fault detector to fast distance protection. Ieee Transactions on Power Delivery 21,  619-626.

Abstract: This paper presents the application of a combined adaptive Fourier filtering technique and fault detector to fast distance protection of transmission lines. The filtering technique is extended from the Fourier filters and can be applied under arbitrary data window length. The proposed filtering technique possesses the advantage of recursive computing, and a decaying dc offset component is removed from fault signals by using an adaptive compensation method. A variable data window scheme is embedded in the technique to adaptively speed tip its transient response under various system and fault conditions. A fault detector is developed to initiate the process of the technique. For the sake of speed and security, two phasor estimation methods based on the proposed technique are designed to achieve fast distance protection. An algorithm consisting of the two methods is used to detect internal faults by "OR" logic. Extensive simulation studies show that the algorithm significantly reduces tripping time of a distance relay and provides better protection performance than that of the conventional filters with fixed data windows
26.   Samantaray, S.R., Dash, P.K., Panda, G., Panigrahi, B.K., 2005. Distance protection of compensated transmission line using computational intelligence. Computational Intelligence and Security, Pt 1, Proceedings 3801, 163-169.

Abstract: A new approach for protection of transmission line including TCSC is presented in this paper. The proposed method includes application of Fuzzy Neural Network for distance relaying of a transmission line operating with a thyristor controlled series capacitor (TCSC) protected by MOVs. Here the fuzzy neural network (FNN) is used for calculating fault location on the TCSC line. The FNN structure is seen as a neural network for training and the fuzzy viewpoint is utilized to gain insight into the system and to simplify the model. The number of rules is determined by the data itself and therefore, a smaller number of rules are produced. The network parameters are updated by Extended Kalman Filter (EKF) algorithm. with a pruning strategy to eliminate the redundant rules and fuzzification neurons resulting in a compact network structure. The input to the FNN are fundamental currents and voltages at the relay end, sequence components of current, system frequency and the firing angle with different operating conditions and the corresponding output is the location of the fault from the relaying point The location tasks of the relay are accomplished using different FNNs for different types of fault (L-G,LL-G,LL, LLL)
27.   Sidhu, T.S., Khederzadeh, M., 2005. TCSC impact on communication-aided distance-protection schemes and its mitigation. Iee Proceedings-Generation Transmission and Distribution 152, 714-728.

Abstract: The paper analyses the impact of the thyristor-controlled series capacitor (TCSC) on the performance of conventional communication-aided distance-protection schemes and proposes new schemes for its mitigation. The associated TCSC control actions introduce rapid changes that create certain problems in the primary-system parameters such as line impedances and load currents, causing the apparent impedance seen by the distance relay to be affected during the fault period; hence the positive-sequence impedance measured by the traditional stand-alone distance relays is no longer an indicator of the distance to a fault. It is shown that communication-aided distance-protection schemes that perform successfully in lines with fixed series capacitors have problems in lines with TCSC. This impact is observed not only on the relays of the compensated fine with TCSC, but also on the relays of adjacent lines. Mitigation of this problem is proposed by using new communication-aided schemes. The proposed schemes use the information available at the substation to inhibit relay malfunctions. The performance of the techniques is studied for different TCSC locations in the transmission line. Real-time digital simulation and commercial relays are used to perform the analysis. The results indicate the effectiveness of the proposed methods to be applied in the power systems equipped with TCSC
28.   Pathirana, V., McLaren, P.G., 2005. A hybrid algorithm for high speed transmission line protection. Ieee Transactions on Power Delivery 20, 2422-2428.

Abstract: A common method used in UHV transmission line protection is based on impedance measurement technique. The fault detection speed of impedance protection schemes cannot be improved without sacrificing the relay reach limit. Protection algorithms based on fault generated transient signals have shown promising results in improving the speed, but these methods have inherent reliability problems. This paper examines how the fault generated transient information can be used to achieve fast fault detection speeds in a distance protection scheme while maintaining a high reliability level
29.   Abdelaziz, A.Y., Ibrahim, A.M., Mansour, M.M., Talaat, H.E., 2005. Modem approaches for protection of series compensated transmission lines. Electric Power Systems Research 75, 85-98.
Abstract: Series compensation has been employed to improve power transfer in long-distance transmission systems worldwide. However, this in turn introduces problems in conventional distance protection. The complex variation of line impedance is accentuated, as the capacitor's own protection equipment operates randomly under fault conditions. This paper proposes two approaches based on travelling waves and artificial neural networks (ANN) for fault type classification and faulted phase selection of series compensated transmission lines. A modal transformation technique, which decomposes the three-phase line into three single-phase lines, is used for this purpose. Algorithms based on two different modal transformations are developed for phase selection and fault classification. Each algorithm is derived from a corresponding truth table. The truth tables are constructed for different types of faults with different faulted phases and different transformation bases. The proposed ANN topology is composed of two levels of neural networks: In level-1, a neural network (ANN(F)) is used to detect the fault. In level-2, four neural networks (ANN(A), ANN(B), ANN(C) and ANN(G)) are used to identify faulted phase(s), and activated by the output of ANN(F) if there is a fault. System simulation and test results, which are presented and analyzed in this paper indicate the feasibility of using travelling waves and ANN in the protection of series compensated transmission lines. (c) 2005 Elsevier B.V. All rights reserved
30.   Joorabian, M., Asl, S.M.A.T., Aggarwal, R.K., 2004. Accurate fault locator for EHV transmission lines based on radial basis function neural networks. Electric Power Systems Research 71, 195-202.
Abstract: This paper describes the design and implementation of an artificial neural networks-based fault locator for extra high voltage (EHV) transmission lines. This locator utilizes faulted voltage and current waveforms at one end of the line only. The radial basis function (RBF) networks are trained with data under a variety of fault conditions and used for fault type classification and fault location on the transmission line. The results obtained from testing of RBF networks with simulated fault data and recorded data from a 400 kV system clearly show that this technique is highly robust and very accurate. The technique takes into account all the practical limitations associated with a real system. Thereby making it possible to effectively implement an artificial intelligence (AI) based fault locator on a real system. (C) 2004 Elsevier B.V. All rights reserved
31.   Soman, S.A., Nguyen, T.B., Pai, M.A., Vaidyanathan, R., 2004. Analysis of angle stability problems: A transmission protection systems perspective. Ieee Transactions on Power Delivery 19, 1024-1033.

Abstract: Postfault rotor angle oscillations lead to power swings. Both unstable and stable swings can induce distance relay tripping. For unstable swings, a new computational procedure to locate all of the electrical centers is developed. It simplifies the work associated with visual screening of all the R-X plots. For stable swings, a generic three-tier hierarchy of stability-related norms defined by branch norm, fault norm, and system norm is proposed. Ranking by branch norm leads to ranking of power swings. Ranking by fault norm leads to ranking of faults or contingencies. Magnitude and rate of change of system norm can be used to detect an out-of-step condition. Results on a ten-machine system and a utility system with detailed models are also presented
32.   Tseng, K.H., Kao, W.S., Lin, J.R., 2003. Load model effects on distance relay settings. Ieee Transactions on Power Delivery 18, 1140-1146.

Abstract: The purpose of this paper is to study load model effects on distance protective relay settings in Taipower's transmission system. Five load models have been used in order to explore the effects of load characteristics on relay settings: (1) static ZIP model, (2) dynamic motor model, (3) composite model, (4) PTI IEEE model, and (5) exponential model. The major points of this study include (1) setting of impedance values for the three distance protective relay zones and the protection against loss of synchronicity in the outermost periphery, (2) exploring the effects of load models on impedance angle at the time of distance relay tripping, (3) study whether the load model will cause a malfunction in the distance relay when the system swings due to a sudden change in the power system, (4). analyze the coordination of the blocking time of the out-of-step blocking relay during system power swings, and (5) propose how to select a better load model for accuracy in relay settings
33.   Chen, C.S., Liu, C.W., Jiang, J.A., 2002. A new adaptive PMU based protection scheme for transposed/untransposed parallel transmission lines. Ieee Transactions on Power Delivery 17, 395-404.
Abstract: This paper proposes a brand-new adaptive phasor measurement unit (PMU) based protection scheme for both transposed and untransposed parallel transmission lines. The development of the scheme is based on the distributed line model and the synchronized phasor measurements at both ends of lines. By means of eigenvalue/eigenvector theory to decouple the mutual coupling effects between parallel lines, the fault detection and location indices are derived. The two proposed indices are used in coordination such that the internal and external fault events can be distinguished completely. By on-line estimating the line parameters under the actual power system conditions, the proposed scheme will respond more accurately to power system faults. Extensive simulation results using EMTP have verified that the accuracy of the fault location achieved is up to 99.9%. The proposed protection system responds well and fast with regard to dependability and security. All the results show that the performance of the proposed detection/location indices is independent of fault types, locations, resistance, source impedance, fault inception angles, and load flows
34.   Hu, Y., Novosel, D., Saha, M.M., Leitloff, V., 2002. An adaptive scheme for parallel-line distance protection. Ieee Transactions on Power Delivery 17, 105-110.

Abstract: This paper describes an adaptive protective relaying scheme for parallel-line distance protection. The scheme adjusts its operation based on the availability of input signals to achieve an optimal distance protection performance on parallel lines influenced by mutual coupling effect. When available, zero sequence current from the parallel line is used to fully compensate the mutual coupling effect. The zero sequence current ratio is used to avoid possible false operations on healthy lines, which may result from such compensation. When the parallel line's zero sequence current is not available, the line operating status is used instead to select the proper zero sequence current compensation factors in impedance calculation. Default zero sequence current compensation factor is used when both the parallel line's zero sequence current and line operating status signals are not available. The performance of the scheme has been verified on a simulated network and the results are presented
35.   Zhe, Z., Li, K.K., Chen, D.S., Yin, X.G., 2001. Stochastic analysis of fault-induced transients for distance relaying application. Electric Power Systems Research 57, 115-121.
Abstract: It is well known that the operation of distance relays relies on the power frequency components to calculate the fault impedance and hence make decision on tripping. It is also discovered that the transient induced during fault has a significant effect on the performance of distance protection, especially on that of the high-speed protection. A better understanding on fault transient can lead to a better relay design and better performance in terms of speed and relay reach. This paper analyzes the fault transients in EHV transmission lines by using time-domain stochastic techniques. Major emphasis are placed in the investigation into the differences between the fault transient attributes of different fault types and the transient features of the composite signals used in distance relay, such as the phase-to-phase quantities. This investigation leads to the development of adaptive approaches that can be implemented in digital distance relays in order to achieve an improved relay performance. (C) 2001 Elsevier Science B.V. All rights reserved
36.   Altuve, H.J., Chacon, O.L., Vazquez, E., Posadas, D., Sanchez, E.N., 1999. Neural-network-based fault location estimator for transmission line protection. Journal of Intelligent & Fuzzy Systems 7, 159-171.

Abstract: PL classical task in the protection of transmission lines against short circuits is the estimation of the electrical distance to the fault and its comparison against a given threshold to determine whether the line is faulted or not. This paper presents a novel neural network approach to this problem, as a step towards the design of a neural protective relay. Two different alternatives are proposed and evaluated in the paper, which resemble the amplitude and phase signal comparison principles currently used in analog protective relays. Obtained results confirm that neural network technology can successfully be used to estimate the fault location for transmission line protection
37.   Oppel, L., Krizauskas, E., 1999. Evaluation of the performance of line protection schemes on the NYSEG six phase transmission system. Ieee Transactions on Power Delivery 14, 110-115.
Abstract: This paper describes the performance of different line protection schemes during testing and operation which were used to protect the first commercially operated six phase transmission line in the world - the New York State Electric and Gas 93kV (phase to phase and phase to ground) line from Goudey station to Oakdale substation. This project was sponsored by Electric Power Research Institute (EPRI), the Department of Energy (DOE), Empire State Electric Energy Research Corporation (ESEERCO), New York State Energy Office (SEO), New York State Energy Research and Development Authority (NYSERDA) and New York State Electric and Gas Corporation (NYSEG)
38.   Waikar, D.L., Chin, P.S.M., 1998. Fast and accurate parameter estimation algorithm for digital distance relaying. Electric Power Systems Research 44, 53-60.
Abstract: Response of digital distance relaying depends on the fast and accurate calculation of parameters such as voltage and current phasors and fault impedance. This paper describes a new apparent impedance estimation algorithm that is based on modal components theory. It is shown in the paper that the proposed algorithm has several advantageous features in terms of speed and accuracy over previously suggested symmetrical and modal components based algorithms. The paper discusses a procedure for deriving a fault impedance estimation algorithm that can be used for protecting power transmission lines. The proposed algorithm was evaluated using an alternative transient program (ATP). The program models a power system, simulates many fault conditions on a selected transmission line and generates fault data. The relay software then obtains filtered, scaled and sampled data and calculates fault impedance using the proposed algorithm. The relay characteristic makes trip decisions based on the fault impedance estimates. The paper shows the feasibility of the proposed algorithm for first zone distance protection. Some results of these studies are presented and discussed in the paper. (C) 1998 Elsevier Science S.A
39.   Khaparde, S.A., Warke, N., Agarwal, S.H., 1996. An adaptive approach in distance protection using an artificial neural network. Electric Power Systems Research 37, 39-44.
Abstract: All relay settings are a compromise. Adaptive relaying accepts that relays that protect a power system may need to change their characteristics to suit the prevailing power system conditions. This philosophy has a wide range of applications covering many protective schemes. Here we consider a two-terminal transmission line, confirm that fault resistance and the location of faults can produce erroneous relay function and finally suggest ways to ensure the generation of the correct signal for relay operation. Retaining the microprocessor based framework, we show how artificial neural networks (ANNs) can be used effectively to achieve adaptive relaying for the above-mentioned problem. Adaptive relaying covers a large number of applications and the characteristics of relays vary widely, so the philosophy of adaptive relaying must vary accordingly. A modified multilayered perceptron model employs an additional node in the input layer. This additional input facilitates changes in the relay characteristic. The desired change in the quadrilateral relay characteristic is achieved by making appropriate changes in the thresholds and weights of the hidden layer neurons. A multiparameter adaptive scheme assumes that the additional input of the phase angle is available. Simulation results using ANNs for the different applications of adaptive relaying mentioned above are presented and discussed
40.   Waikar, D.L., Liew, A.C., Elangovan, S., 1996. Design implementation and performance evaluation of a new digital distance relaying algorithm. Ieee Transactions on Power Systems 11, 448-456.
Abstract: This paper presents the design, simulation, implementation and. performance evaluation of a computationally efficient and accurate digital distance relaying algorithm. Published historical data were used in the first phase for validation purpose. Sample results illustrating highly accurate fault impedance estimates for various conditions are reported. The second phase uses voltage and current signals generated by Alternative Transients Program (ATP) and a sample power system for various first-zone, second-zone and third-zone faults. Results of these studies confirming stability and computational efficiency of the algorithm are presented and discussed. In the third phase, a prototype of the relay was developed and tested using real-time fault data generated from physical models of the transmission Lines. Oscillographs for these conditions were recorded. Results of these tests indicating high speed relay operation are also discussed. The performance evaluation studies reported in this paper conclusively demonstrate that the new algorithm provides fast and accurate fault impedance estimates for the three-zone protection of transmission lines
41.   Lian, B., Salama, M.M.A., 1996. An overview of the digital fault location algorithms for the power transmission line protection based on the steady-state phasor approaches. Electric Machines and Power Systems 24, 83-115.
Abstract: The fault location algorithm is a key element in the digital relay for power transmission line protection. The core of the algorithm is the relaying function which relates the fault distance to the sampled waveforms. Various relaying functions are used, so far, based mainly on the steady-state phasor approach, the differential equation approach and the traveling-wave approach, respectively. In this paper, the steady-state phasor approaches are reviewed. The effect of various algorithms on relay speed and accuracy is examined regarding the selection of the system model, the relaying function and the filtering technique
42.   Waikar, D.L., Elangovan, S., Liew, A.C., Sng, S.H., 1995. Real-Time Assessment of A Symmetrical Component and Microcontroller Based Distance Relay. Electric Power Systems Research 32, 107-112.

Abstract: This paper presents the design, implementation and real-time assessment of a microcontroller based digital distance relay that can be used for the protection of power transmission lines. The proposed design is implemented using a general-purpose Intel 8097 microcontroller and custom-made filters, operational amplifiers, sample-and-hold amplifiers, multiplexers, and analog-to-digital converters. The relay software is based on a computationally efficient symmetrical component based fault distance estimation algorithm. Results of the performance assessment studies on this algorithm have shown promising fault distance estimates for first-zone faults on the protected transmission line. Real-time implementation of the symmetrical component based fault distance estimation algorithm is presented and discussed in this paper. Hardware and software tools were used to design and fabricate a microcontroller based distance relay using the above-mentioned algorithm. This paper describes details of the design of the distance relay. A test setup in the laboratory using a transmission line model was used to generate data to assess the real-time response of the designed relay. High-speed relay operation of the order of one cycle is demonstrated in the test results
43.   Waikar, D.L., Liew, A.C., Elangovan, S., 1995. 2Nd-Zone and 3Rd-Zone Performance Assessment of A Symmetrical Component Based Improved Fault Impedance Estimation Method. Electric Power Systems Research 32, 113-120.
Abstract: The performance assessment of a symmetrical component based fault impedance estimation method that has previously been proposed by the authors is discussed in this paper. A brief review of the proposed method is given. The personal computer based Alternative Transient Program was used in these performance assessment studies. Voltage and current signals for various fault conditions were generated by simulating different types of fault on a selected transmission line of a sample power system. These signals were processed, sampled, and used in the proposed method. The apparent impedance of the protected transmission line from the relay location up to the fault point was calculated using the proposed method. These impedance estimates were inserted in R-X plane characteristics to determine the suitability of the proposed method for digital distance protection of the second and third zones. The results of these performance assessment studies are presented and discussed in the paper
44.   Glazman, E.S., 1993. Echo-Signal Protection for A Tv Receiver Network. Telecommunications and Radio Engineering 48, 1-8.
Abstract: It was found in the early stage of the development of modern television broadcasting in the VHF and UHF bands that the reception of pictures in most cases is accompanied by distortions in the form of ghost images (ghosts) spaced at a certain distance from the picture element. Ghosts are caused by an accompanying stream of echo signals propagating in the radio channel. Sources include the transmitter channel and its antenna feeder, the antenna and receiver, repeaters and radio relay and cable radio links, if their parameters do not meet the requirements of undistorted transmission. Although, in the end, satisfactory operation has been achieved at the price of rigid standardization of the performance characteristics of all elements in the radio channel, acceptable reception quality has not been attained due to multipath signal reception. In most cases, indoor antennas cannot be used for reception; common-use antennas and residential building cable networks came to be used and recently cable television networks have been employed. An alternative method of suppressing ghosts is to use so-called anti-echo devices in each television receiver; a number of patents have been issued on such devices in many countries. The devices complicate and increase the cost of the television and have not yet found wide application. Their use in certain new television receiver models in, for example, Japan has still failed to keep millions of viewers from seeing ghosts on their television screens. The problem of finding a method of protecting the entire television receiver network from this phenomenon without using additional anti-echo devices in the television receivers is presented in this paper for what we believe is the first time
45.   Waikar, D.L., Elangovan, S., Liew, A.C., 1994. Fault Impedance Estimation Algorithm for Digital Distance Relaying. Ieee Transactions on Power Delivery 9, 1375-1383.
Abstract: Fault impedance is one of the major parameters that must be estimated accurately in digital distance relaying application. In this paper, a new algorithm is proposed based on symmetrical components theory. The proposed algorithm has computational advantage over previously suggested symmetrical components based algorithms. A procedure for applying shunt fault conditions to the sequence equations to estimate fault impedance of the protected transmission line is discussed. Alternative Transient Program (ATP) that is available on personal computers was used in evaluating the proposed algorithm. ATP models a power system arid simulates many fault conditions on a selected transmission line. Fault data obtained were used in calculating fault impedance using the proposed algorithm. Fault impedance estimates were inserted in relay characteristics to determine suitability of the proposed algorithm for first zone distance protection. Sample results of these studies which show stable fault distance estimates are presented and discussed in the paper
46.   Waikar, D.L., Liew, A.C., Elangovan, S., 1993. 1St-Zone Performance Assessment of A Symmetrical Component Based Improved Fault Impedance Estimation Method. Electric Power Systems Research 27, 161-168.
Abstract: This paper describes the first-zone performance assessment of a symmetrical component based fault impedance estimation method that has previously been proposed by the authors. The performance equation of the proposed method is briefly reviewed and various performance assessment techniques are also discussed. The Alternative Transient Program, which is available on personal computers, was used in these performance assessment studies. This Program was used to model a power system and to simulate many fault conditions on a selected transmission line. Fault data thus obtained were used in calculating the fault impedance using the proposed method. Fault impedance estimates were inserted in R-X plane characteristics to determine the suitability of the proposed method for first-zone digital protection. The results of these performance assessment studies are presented and discussed in the paper
47.   Waikar, D.L., Elangovan, S., Liew, A.C., 1993. Symmetrical Component Based Improved Fault Impedance Estimation Method for Digital Distance Protection .1. Design Aspects. Electric Power Systems Research 26, 143-147.

Abstract: Recently, distance relays using digital processors have received considerable attention from researchers. The digital processor based distance relays use estimates of fault impedance (distance) in making decisions. Several methods have been suggested in the past that can be used to estimate fault distance. Researchers have proposed symmetrical component, Clark's component and modal component theories for developing distance estimation methods. The approach used in the symmetrical component based methods has resulted in a higher computational burden on the digital processor, which was addressed using special hardware or multiprocessors. In the present paper, an improved method is proposed that also uses symmetrical component transformation. The simplified approach used in the proposed method leads to a computational advantage over previously suggested symmetrical component based methods. The paper derives performance equations that are valid for ten types of shunt fault encountered on transmission lines. The basis for analyzing shunt faults on the transmission line model and developing the fault estimation method is discussed in detail. The proposed method is also validated using numerical examples, the results of which are reported in Part II of this paper (Electr. Power Syst. Res., 26 (1993) 149-154)


  1. Increasingly, over head transmission lines are routed through areas of poor ground conditions, often for reasons of amenity. This results in the need for the use of special, generally larger, foundations.

  2. over head transmission lines planning, routing, and design and material supply within a stipulated time schedule is must.