Showing papers in "IEEE Transactions on Power Delivery in 2006"
TL;DR: In this article, a modification of the vector fitting (VF) procedure for rational function approximation of frequency-domain responses is described. But the modification is limited to the case of single-input single-out (SISO) transmission lines.
Abstract: This paper describes a modification of the vector fitting (VF) procedure for rational function approximation of frequency-domain responses. The modification greatly improves the ability of VF to relocate poles to better positions, thereby improving its convergence performance and reducing the importance of the initial pole set specification. This is achieved by replacing the high-frequency asymptotic requirement of the VF scaling function with a more relaxed condition. Calculated results demonstrate a major improvement of performance when fitting responses that are contaminated with noise. The procedure is also shown to be advantageous for wideband modeling of transmission lines, network equivalents, and transformers.
684 citations
TL;DR: This paper presents an algorithm for network reconfiguration based on the heuristic rules and fuzzy multiobjective approach for minimizing the number of tie-switch operations.
Abstract: This paper presents an algorithm for network reconfiguration based on the heuristic rules and fuzzy multiobjective approach. Multiple objectives are considered for load balancing among the feeders and also to minimize the real power loss, deviation of nodes voltage, and branch current constraint violation, while subject to a radial network structure in which all loads must be energized. These four objectives are modeled with fuzzy sets to evaluate their imprecise nature and one can provide his or her anticipated value of each objective. Heuristic rules are also incorporated in the algorithm for minimizing the number of tie-switch operations. The effectiveness of the proposed method is demonstrated through an example.
453 citations
TL;DR: A neural-network (NN)-based approach to nonintrusive harmonic source identification and MLP was found to be the best signature identification method because of its low computational requirements and ability to extract the information necessary for highly accurate device identification.
Abstract: This paper proposes a neural-network (NN)-based approach to nonintrusive harmonic source identification. In this approach, NNs are trained to extract important features from the input current waveform to uniquely identify various types of devices using their distinct harmonic "signatures". Such automated, noninvasive device identification will be critical in future power-quality monitoring and enhancement systems. Several NN-based classification models including multilayer perceptron (MLP), radial basis function (RBF) network, and support vector machines (SVM) with linear, polynomial, and RBF kernels were developed for signature extraction and device identification. These models were trained and tested using spike train data gathered from the Fourier analysis of the input current waveform in the presence of multiple devices. The performance of these models was compared in terms of their accuracy, generalization ability, and noise tolerance limits. The results showed that MLPs and SVM were both able to determine the presence of devices based on their harmonic signatures with high accuracy. MLP was found to be the best signature identification method because of its low computational requirements and ability to extract the information necessary for highly accurate device identification.
427 citations
TL;DR: In this article, the authors present a multiobjective performance index for distribution networks with distributed generation, which considers a wide range of technical issues and is extensively located and sized within the IEEE-34 test feeder.
Abstract: Evaluating the technical impacts associated with connecting distributed generation to distribution networks is a complex activity requiring a wide range of network operational and security effects to be qualified and quantified. One means of dealing with such complexity is through the use of indices that indicate the benefit or otherwise of connections at a given location and which could be used to shape the nature of the contract between the utility and distributed generator. This paper presents a multiobjective performance index for distribution networks with distributed generation which considers a wide range of technical issues. Distributed generation is extensively located and sized within the IEEE-34 test feeder, wherein the multiobjective performance index is computed for each configuration. The results are presented and discussed.
390 citations
TL;DR: In this article, the fault detection and its clearing time are determined based on a set of rules obtained from the current waveform analysis in time and wavelet domains, which is able to single out faults from other power quality disturbances, such as voltage sags and oscillatory transients, which are common in power systems operation.
Abstract: This paper proposes a novel method for transmission-line fault detection and classification using oscillographic data. The fault detection and its clearing time are determined based on a set of rules obtained from the current waveform analysis in time and wavelet domains. The method is able to single out faults from other power-quality disturbances, such as voltage sags and oscillatory transients, which are common in power systems operation. An artificial neural network classifies the fault from the voltage and current waveforms pattern recognition in the time domain. The method has been used for fault detection and classification from real oscillographic data of a Brazilian utility company with excellent results
348 citations
TL;DR: In this article, a unified power quality conditioner with the distributed generation is proposed, which consists of a series inverter, a shunt inverter and a distributed generator connected in the dc link through a rectifier.
Abstract: This paper describes analysis results of a combined operation of the unified power quality conditioner with the distributed generation. The proposed system consists of a series inverter, a shunt inverter, and a distributed generator connected in the dc link through a rectifier. The proposed system can compensate voltage sag and swell, voltage interruption, harmonics, and reactive power in both interconnected mode and islanding mode. The performance of proposed system was analyzed using simulations with power system computer aided design/electromagnetic transients dc analysis program, and experimental results with the hardware prototype. The proposed system can improve the power quality at the point of installation on power distribution systems or industrial power systems.
331 citations
TL;DR: In this article, the authors present a hybrid breaker, which combines a high-speed mechanical switch and a bi-directional integrated gate-controlled thyristor assembly connected in parallel.
Abstract: Air-magnetic circuit breakers are widely used for short-circuit protection in dc electric railways or industrial plants. The well-known drawbacks of these breakers are mainly a slow breaking action, a short lifetime, and high maintenance costs due to the destructive effects of the arc. The use of power semiconductors in a full-static circuit breaker configuration allows the elimination of these disadvantages but is limited by excessive conduction losses. The paper will present the study of a so-called hybrid breaker, drawing its name from the combination of a high-speed mechanical switch and a bi-directional integrated gate-controlled thyristor assembly connected in parallel. The paper also includes experimental results from a prototype real scale.
300 citations
TL;DR: In this paper, a unified dynamic model and control schemes for a grid-connected static energy conversion system that is based on the voltage-sourced converter (VSC) configuration are presented.
Abstract: This paper introduces and develops i) a novel unified dynamic model, and ii) new control schemes for a grid-connected static energy conversion system that is based on the voltage-sourced converter (VSC) configuration. The model and the controls are applicable to both the conventional two-level and the three-level neutral point diode clamped (NPC) VSCs. The model is unified since it represents the dynamic behavior of the VSC with respect to both positiveand negative-sequence components, due to unbalanced grid conditions and disturbances. To develop the unified model, the concepts of "generalized sinusoidal pulse-width modulation (SPWM)" and "VSC sequence subsystems" are presented. Based on the negative-sequence subsystem control, a new control strategy, to either balance the ac line currents or to mitigate dc-bus voltage ripples, is introduced. Application of the developed model and the controls to a variable-speed wind-power unit is presented in the paper.
293 citations
TL;DR: In this article, a comparative study of the modeling and simulation of the first CIGRE HVDC benchmark system using two simulation tools PSCAD/EMTDC and PSB/SIMULINK is presented.
Abstract: This paper focuses on a comparative study of the modeling and simulation of the first CIGRE HVDC benchmark system using two simulation tools PSCAD/EMTDC and PSB/SIMULINK; an interface between them (PSCAD-SIMULINK) has also been implemented and used as a simulator. The CIGRE HVDC system and its controller has been carefully modeled in all three simulation environments so that the differences are minimal. Comparison of steady-state and transient situations have been carried out, and a high degree of agreement in most of the cases has been observed.
274 citations
TL;DR: It is shown that there is no statistically significant difference in performance of the proposed method for PQ classification when different wavelets are chosen, which means one can choose the wavelet with short wavelet filter length to achieve good classification results as well as small computational cost.
Abstract: This paper proposed a novel approach for the Power Quality (PQ) disturbances classification based on the wavelet transform and self organizing learning array (SOLAR) system. Wavelet transform is utilized to extract feature vectors for various PQ disturbances based on the multiresolution analysis (MRA). These feature vectors then are applied to a SOLAR system for training and testing. SOLAR has three advantageous over a typical neural network: data driven learning, local interconnections and entropy based self-organization. Several typical PQ disturbances are taken into consideration in this paper. Comparison research between the proposed method, the support vector machine (SVM) method and existing literature reports show that the proposed method can provide accurate classification results. By the hypothesis test of the averages, it is shown that there is no statistically significant difference in performance of the proposed method for PQ classification when different wavelets are chosen. This means one can choose the wavelet with short wavelet filter length to achieve good classification results as well as small computational cost. Gaussian white noise is considered and the Monte Carlo method is used to simulate the performance of the proposed method in different noise conditions.
265 citations
TL;DR: In this article, an active islanding detection method for electronically-interfaced distributed resource units at the distribution voltage level is presented, which is based on injecting a disturbance signal into the system through either the direct or quadrature axis (q-axis) current controllers of the interface voltage-sourced converter.
Abstract: This paper presents an active islanding detection method for electronically-interfaced distributed resource units at the distribution voltage level. The proposed method is based on injecting a disturbance signal into the system through either the direct axis (d-axis) or the quadrature axis (q-axis) current controllers of the interface voltage-sourced converter. Signal injection through the d-axis controller modulates the amplitude of the voltage at the point of common coupling (PCC), whereas signal injection through the q-axis controller causes a frequency deviation at PCC, under islanded conditions. Monitoring strategies to detect islanding are also presented for the proposed injection method. The feasibility of the proposed method is evaluated under the UL1741 anti-islanding test configuration. The studies reported in this paper are based on time-domain simulations in the PSCAD/EMTDC environment. The studies show that the proposed islanding detection method succeeds in detecting the islanding phenomenon as fast as 33.3 ms for the parameter setting of the test system, and always meets the two-second UL detection requirement. The paper also concludes that the proposed method has the salient feature of offering a potential application in a micro-grid scenario, where fast "islanding detection" and not necessarily the "anti-islanding function" is required.
TL;DR: Experimental tests show that the approach is feasible and efficient, so the prototype program based on the approach are promising to be used in a large transmission power system for online fault diagnosis.
Abstract: In this paper, three element-oriented models based on simplified Bayesian networks with Noisy-Or and Noisy-And nodes are proposed to estimate the faulty section of a transmission power system. The three models are used to test if any transmission line, transformer, or busbar within a blackout area is faulty. They can deal with uncertain or incomplete data and knowledge relating to power system diagnosis, so they are flexible. The structures and initial parameters of the Bayesian networks depend on the prior knowledge of the domain experts. The parameters can be revised by using an error back propagation algorithm similar to the back-propagation algorithm for artificial neural networks. The fault diagnosis models do not vary with the change of the network structure, so they can be applied to any transmission power system. Furthermore, they have clear semantics, rapid reasoning, powerful error tolerance ability, and no convergence problem during the diagnosing procedure. Experimental tests show that the approach is feasible and efficient, so the prototype program based on the approach is promising to be used in a large transmission power system for online fault diagnosis.
TL;DR: In this article, a model developed for a transformer monitoring system to estimate transformer tank vibration is presented, which takes into account the main physical phenomena generating vibrations in the different transformer elements and how these vibrations are superposed and transmitted to the tank.
Abstract: In this paper, a model developed for a transformer monitoring system to estimate transformer tank vibration is presented. The model calculates vibration on the transformer tank starting from some input variables that can be easily measured on the transformer. Tank vibration is also measured, showing a good concordance between estimated and measured values if the transformer is healthy. In case of a winding deformation winding vibration and, consequently, that of the tank, changes and a big difference between estimated and measured vibration appear. To estimate tank vibration, the model takes into account the main physical phenomena generating vibrations in the different transformer elements and how these vibrations are superposed and transmitted to the tank. The model has been tested experimentally on a test transformer fitted with internal and external accelerometers. A deformation has been provoked in the test transformer winding with the aim of testing the model's ability to detect it. The model has been also tested on several in-service grid transformers. The results of the experimental validation are shown in Part II of the paper.
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TL;DR: In this article, the authors reexamine the application of zone 3 and describe situations where it can be properly utilized, where zone 3 can be removed without reducing the reliability of the system protection and, if used, how to modify or set.
Abstract: Zone 3 of a step-distance protection scheme has been identified as one of the contributing causes of cascading failures in power systems. The National Electric Reliability Council (NERC) has issued rules, and the IEEE Power System Relaying Committee (PSRC) has discussed recommendations to reduce the undesirable operation of this component of the protection chain. It is the purpose of this paper to reexamine the application of zone 3, to describe situations where it can be properly utilized, where it can be removed without reducing the reliability of the system protection and, if used, how it can be modified or set. A table is presented for a variety of station designs and protection schemes including two common local backup relay systems and the associated application of a remote third zone. Finally, the concept of critical locations is introduced which can assist the relay engineer in determining if potential zone 3 undesirable operations are a serious threat to the system and help determine if the expense and difficulty of removing zone 3 or modifying the relay or its associated station is justified.
TL;DR: In this article, the authors investigate how power phenomena and properties of three-phase systems are described and interpreted by the Instantaneous Reactive Power (IRP) p-q Theory.
Abstract: This paper investigates how power phenomena and properties of three-phase systems are described and interpreted by the Instantaneous Reactive Power (IRP) p-q Theory. This paper demonstrates that this theory misinterprets power properties of electrical systems or provides some results that at least defy a common sense or meaning of some notions in electrical engineering. For example, it suggests the presence of an instantaneous reactive current in supply lines of purely resistive loads and the presence of an instantaneous active current in supply lines of purely reactive loads. Moreover, it suggests that line currents of linear loads with sinusoidal supply voltage contain a nonsinusoidal component. This paper shows, moreover, that the IRP p-q Theory is not capable to identify power properties of three-phase loads instantaneously. A pair of instantaneous values of p and q powers does not allow us to conclude whether the load is resistive, reactive, balanced, or unbalanced. It is known that a load imbalance reduces power factor. However, the IRP p-q Theory does not identify the load imbalance as the cause of power factor degradation.
TL;DR: In this paper, the state-of-the-art in modern sensor, communication, and protection technologies is presented. But, the authors do not discuss the integration of wide-area measurements and their integration in protection and control systems.
Abstract: Wide area measurements have been widely used in the energy management systems (EMS) of power systems for monitoring, operation, and control. In recent years, the advent of synchronized phasor measurements has added another dimension to the field of wide-area measurements. At the same time, the field of protection systems has been dominated by computer based relays, which make it relatively easy to communicate with relays and thus include them in many innovative protection systems. Special Protection Systems (SPS) or Remedial Action Schemes (RAS) are one example of integration of communication and protection systems. In recent years—due to operational demands imposed on transmission networks by deregulation it has become clearer that wide-area measurements and their integration in protection and control systems is a necessity. This paper documents the state-of-the-art in modern sensor, communication, and protection technologies which show great potential for innovations in protection and control systems for the future.
TL;DR: In this article, the authors provide an open access to the frequency domain spectra of oil impregnated paper and pressboard samples, which can then be used in modeling of the results of diagnostic measurements in power transformers.
Abstract: Knowledge about moisture content in oil impregnated paper insulation is essential when estimating remaining lifetime of power transformers. Direct evaluation of moisture content is rarely possible due to inaccessibility of the internal insulation system in transformers. Therefore, various indirect estimation techniques are utilized. Frequency domain spectroscopy (FDS) measurements of transformer insulation belong to this group. To perform high quality interpretation of results of FDS measurements a good knowledge on dielectric responses in oil impregnated pressboard and paper is required, especially as it refers to their variation with water content and temperature. The aim of this paper is to provide an open access to the frequency domain spectra of oil impregnated paper and pressboard samples, which can then be used in modeling of the results of diagnostic measurements in power transformers.
TL;DR: The authors propose a new method of power-quality classification using support vector machine (SVM) neural networks using space phasor for feature extraction from three-phase signals to build distinguished patterns for classifiers.
Abstract: The authors propose a new method of power-quality classification using support vector machine (SVM) neural networks. Classifiers based on radial basis function (RBF) networks was, in parallel, applied to enable proper performance comparison. Both RBF and SVM networks are introduced and are considered to be an appropriate tool for classification problems. Space phasor is used for feature extraction from three-phase signals to build distinguished patterns for classifiers. In order to create training and testing vectors, different disturbance classes were simulated (e.g., sags, voltage fluctuations, transients) in Matlab. Finally, the investigation results of the novel approach are shown and interpreted.
TL;DR: In this article, a generalized leader inception model is proposed based on an iterative geometrical analysis of the background potential distribution of an earthed structure to simulate the first meters of propagation of an upward connecting leader.
Abstract: In this paper, a generalized leader inception model is proposed. It is based on an iterative geometrical analysis of the background potential distribution of an earthed structure to simulate the first meters of propagation of an upward connecting leader. By assuming a static field approach, the leader stabilization fields and the striking distances were computed for a lightning rod and for a building. The obtained results were compared with the existing leader inception criteria. Furthermore, in order to validate the model, the leader inception condition was computed for a triggered lightning experiment. Excellent agreement with the experimental results was obtained. The present model has several advantages in comparison with the existing leader inception criteria. One of them is related to the fact that the proposed model can be used to analyze the effect of the space charge on the upward leader inception.
TL;DR: In this paper, the impact of the interface control strategy of inverter-based DGs on islanding detection is examined and the Nondetective Zone (NDZ) is derived analytically for each interface control and validated by simulation.
Abstract: Islanding detection of Distributed Generation (DG) is considered as one of the most important aspects when interconnecting DGs to the distribution system. With the increasing penetration and reliance of the distribution systems on DGs, new interface control strategies are being proposed. Aside from its main task of supplying active power, the DG could provide voltage support, improve the power factor, or mitigate other power quality problems. This paper examines the impact of the interface control strategy of inverter based DGs on islanding detection. The Nondetective Zone (NDZ) for over/under voltage and over/under frequency is derived analytically for each interface control and validated by simulation.
TL;DR: In this paper, an auxiliary subsynchronous damping controller (SSDC) is proposed to damp subsynchronic resonance (SSR) caused by series capacitors with the help of a static synchronous compensator (STATCOM).
Abstract: A long transmission line needs controllable series as well as shunt compensation for power flow control and voltage regulation. This can be achieved by suitable combination of passive elements and active FACTS controllers. In this paper, series passive compensation and shunt active compensation provided by a static synchronous compensator (STATCOM) connected at the electrical center of the transmission line are considered. It is possible to damp subsynchronous resonance (SSR) caused by series capacitors with the help of an auxiliary subsynchronous damping controller (SSDC) on STATCOM. The objective of this paper is to investigate the SSR characteristics of the system and propose a new design procedure for SSDC based on nonlinear optimization to meet the specifications on the damping torque in the range of critical torsional frequencies. The SSDC uses the Thevenin voltage signal to modulate the reactive current reference of STATCOM. The Thevenin voltage signal is derived from the locally available STATCOM bus voltage and reactive current signals. The STATCOM configurations considered in this paper are 12 pulse, two- and three-level voltage source converter with Type-2 and Type-1 control, respectively. The controller regulates either reactive current (supplied by the STATCOM) or the bus voltage. The 3-phase model of the STATCOM is based on switching functions. By neglecting harmonics in the switching function, D-Q model is derived which is combined with similar models of the other system components for linear analysis. The results of the linear analysis are validated by carrying out transient simulation based on the detailed nonlinear models. The study is performed on the system adapted from the IEEE First Benchmark Model.
TL;DR: In this article, the authors investigated the effect of weight factors and far-end faults in the relay coordination problem formulation and showed that the relay quality is not lost by considering these factors.
Abstract: Considerations of weight factors and far-end faults in the directional overcurrent relay coordination problem formulation do not affect the optimal solution. This paper investigates this viewpoint and verifies that indeed by such an approach the optimality is not lost. But, this study reveals that in doing so, the coordination quality is sacrificed to some extent. It is also observed that if all remaining valid constraints (after relaxing few constraints based on the back-up coordination philosophy and strength of fault level generated) are considered and if the objective function is changed to running sum of all violating constraints, all valid considered constraints are satisfied. This study is done by simultaneously optimizing all settings in nonlinear environment by Sequential Quadratic Programming method using Matlab Toolbox. The results of the analysis on a sample 6-bus and IEEE 30-bus systems are presented in this paper.
TL;DR: In this paper, a multiobjective approach for the design of electrical distribution networks is presented, where the objectives are defined as a monetary cost index (including installation cost and energy losses cost) and a system failure index.
Abstract: This paper presents a multiobjective approach for the design of electrical distribution networks. The objectives are defined as a monetary cost index (including installation cost and energy losses cost) and a system failure index. The true Pareto-optimal solutions are found with a multiobjective genetic algorithm that employs an efficient variable encoding scheme and some problem-specific mutation and crossover operators. Results based on 21- and 100-bus systems are presented. The information gained from the Pareto-optimal solution set is shown to be useful for the decision-making stage of distribution network evolution planning.
TL;DR: In this article, a system modeling and control design for fast load voltage regulation using static compensators (STATCOMs) is presented, which gives a clear representation of load voltage magnitude and STATCOM reactive current on an instantaneous basis.
Abstract: This paper presents system modeling and control design for fast load voltage regulation using static compensators (STATCOMs). The modeling strategy gives a clear representation of load voltage magnitude and STATCOM reactive current on an instantaneous basis. The particular coordinate transformation employed here also facilitates extraction of linearized system dynamics in conjunction with circuit simulators. It is rigorously shown that the control problem of load voltage regulation using reactive current is nonminimum phase. Linear and nonlinear controllers for the regulation problem are designed and compared via simulation results. Internal dynamics of the STATCOM are modeled using the same strategy. Lyapunov based adaptive controllers are designed for controlling the STATCOM reactive current while maintaining its dc bus voltage. Simulation results of the controlled STATCOM integrated with the load bus voltage controller are presented to show efficacy of the modeling and control design.
TL;DR: In this paper, the impact of TCSC on the protection of transmission lines is analyzed by using simple models, then the power system and the protective relays are simulated in detail by Real Time Digital Simulator (RTDS).
Abstract: This paper presents a comprehensive analysis of the impact of TCSC on the protection of transmission lines. The TCSC is considered as a dynamical device and its transient process is modeled in order to have the response to disturbances based on its own control strategy. It is shown that not only the TCSC affects the protection of its line, but also the protection of adjacent lines would experience problems. The analysis is done first analytically by using simple models, then the power system and the protective relays are simulated in detail by Real Time Digital Simulator (RTDS). Finally, the simulation results are validated by using a commercial relay.
TL;DR: In this article, a generalized methodology for stochastic/probabilistic assessment of the annual financial losses due to interruptions and voltage sags is presented, which takes into account all the uncertainties associated with the voltage sag calculation, sensitivity of customers' equipment to voltage sag, the interconnection of the equipment within an industrial process, and customer types and the location of the process in the network.
Abstract: This paper presents a generalized methodology for stochastic/probabilistic assessment of the annual financial losses due to interruptions and voltage sags. The costs of interruptions and voltage sags are treated separately and then combined in order to estimate the total financial losses in the network per annum. The methodology proposed is applicable to both assessment of individual customer losses and assessment of total network losses. It takes into account in a probabilistic manner all the uncertainties associated with the voltage sag calculation, sensitivity of customers' equipment to voltage sags, the interconnection of the equipment within an industrial process, and customer types and the location of the process in the network.
TL;DR: In this paper, a case study for a 10MW wind farm, intended to be connected to a network with extended high-voltage submarine cable lines, is presented, where the harmonic impedance of the system is calculated for a variety of configurations and operating conditions, and its main characteristics are discussed.
Abstract: Variable-speed wind turbines inject harmonic currents in the network, which may potentially create voltage distortion problems. In this paper, a case study is presented for a 10-MW wind farm, intended to be connected to a network with extended high-voltage submarine cable lines. First, the system modeling approach and the harmonic load-flow calculation is described. Then, the harmonic impedance of the system is calculated for a variety of configurations and operating conditions, and its main characteristics are discussed. Harmonic load-flow calculations are provided to indicate potential voltage distortion problems. A simplified methodology, suggested in relevant IEC publications, is applied to the system and its results are compared to those of the harmonic load flow. A discussion on the summation of harmonic currents within a wind farm is also included
TL;DR: In this paper, the authors proposed a new signal processing methodology based on the continuous wavelet transform that is calculated at a suitably large scale to confirm the nature of the fault and to infer the true fault location.
Abstract: Single-ended unsynchronized traveling-wave fault-location algorithms have been around for several years. They avoid the costs and complexities associated with remote-end synchronization. Nevertheless, there is a corresponding increase in required signal processing as each reflection must be identified and then related in time to the signal wavefront. The current signal processing techniques include a combination of modal and wavelet analysis, where the resulting vectors are often squared. However, the performance of this process degrades dramatically with the filtering associated with the substation transducers and secondary circuits. Furthermore, the variation in observed reflection patterns demonstrates that these methods cannot adequately distinguish between faults on the near, or far half of the transmission line. This paper considers the traveling-wave data observed on a 330-kV transmission system and presents a new signal processing methodology to cater for the observations. This is based on the continuous wavelet transform that is calculated at a suitably large scale. The polarities of the resulting coefficients are used to confirm the nature of the fault and to infer the true fault location.
TL;DR: In this paper, a new method for the boundary protection of series-compensated transmission lines, as well as fault classification is presented, which is based on detecting distinct frequency bands contained in the transient fault current wave.
Abstract: This paper presents a new method for the boundary protection of series-compensated transmission lines, as well as fault classification. The boundary protection is based on detecting distinct frequency bands contained in the transient fault current wave. Discrete wavelet transform, using db4 as a mother wavelet, is used to capture two bands of frequencies in the transient current signal. The spectral energies of these two bands are obtained and used to determine if the fault is internal or external to the protected zone. Fault classification is done using the discrete wavelet transform. Using Haar as the mother wavelet, the coefficients of a frequency band in the range of 1 kHz-3 kHz are obtained for the three phase and ground currents. The average value of the coefficients of each current wave is then computed and used to classify the faulted phases. The basic principle of the protection scheme is described and its response to the series-compensated transmission lines is studied for a wide range of compensation levels, fault conditions, fault types, and fault locations. The stability of the algorithm under various load switching cases is also tested. Fault simulations are performed using power system computer-aided design/electromagnetic transient and direct current program and the results are then interfaced to MATLAB, where the algorithm is implemented. It is found that the proposed method gives reliable results in the boundary protection and fault classification of series-compensated lines.
TL;DR: In this paper, a wavelet-based high-impedance fault (HIF) detector has been proposed for distribution networks with the application of wavelet transform technique, which can be used for HIF detection independent of the network neutral-point grounding mode.
Abstract: A new simple and effective algorithm of arcing fault detection in distribution networks with the application of a wavelet transform technique is presented in this paper. The protection algorithm developed observes the phase displacement between wavelet coefficients calculated for zero-sequence voltage and current signals at a chosen high-level frequency. The final decision in regards to feeder switching off (or alarm issuing) is met either with a deterministic logic scheme or with the use of a neural net trained especially for that purpose. The developed wavelet-based high-impedance fault (HIF) detector has been tested with Electromagnetic Transients Program-Alternative Transients Program (ATP)-generated signals, exhibiting better performance than traditionally used algorithms and methods. The protection method proposed may be used for HIF detection independent of the network neutral-point grounding mode. The scheme proved to be robust against transients generated during normal events such as feeder energizing and de-energizing as well as capacitor bank switching