Fault Inception Angle Research Articles

Fuzzy based relaying scheme for high impedance faults in DG integrated distribution system

Most of the high impedance faults (HIF) remain un-detected by the conventional relays due to non-linear nature of the fault and low magnitude of current. In this work, a combination of discrete wavelet transforms (DWT) and fuzzy inference system (FIS) has been proposed for HIF detection and classification. Modified IEEE 13 node test feeder system has been to validate the proposed scheme. The proposed method uses current signals from one end that are pre-processed using discrete wavelet transform to obtain appropriate input features. The wavelet processed features are given to the FIS for fault detection and classification. Proposed method has been validated using both Mamdani and Sugeno type FIS. Different operating and fault conditions are tested to validate the proposed method such as varying DG parameters, noisy signals, HIFs, evolving faults, fault inception angle, fault resistance, fault location, and non-fault events (e.g. motor load switching, capacitor switching, DG switching, transformer energization, non-linear load switching). The accuracy in detecting and classifying the faults is 100% of all the tested fault cases. Results shows that the overall detection time required to detect the HIFs is minimum 4.25 cycles in most of the cases and maximum 8 cycles in few cases whereas for shunt faults is within 4.25 to 6 cycles only. Advantage of the proposed method is that it can detect adverse situation faults like evolving faults, in presence of noisy signals and remains intact against any switching events. The results of the proposed method are promising and the method is robust against various operating conditions.

A Novel Faulty Phase Selection Method for Single-Phase-to-Ground Fault in Distribution System Based on Transient Current Similarity Measurement

In modern electrical power distribution systems, the effective operation of inverter-based arc suppression devices relies on the accuracy of faulty phase selection. In the traditional methods of faulty phase selection for single-phase-to-ground faults (SPGs), power frequency-based amplitude and phase characteristics are used to identify the faulty phase. In the field, when a high-resistance SPG occurs in the system, traditional methods are difficult for accurately identifying the faulty phase because of the weak fault components and complicated process. A novel realizable and effective method of faulty phase selection based on transient current similarity measurements is presented when SPGs occur in resonantly grounded distribution systems in this paper. An optimized Hausdorff distance matrix (MOHD) is proposed and constructed by the transient currents of three phases’ similarity measurements within a certain time window of our method. This MOHD is used to select the sampling time window adaptively, which allows the proposed method to be applied to any scale of distribution systems. Firstly, when a SPG occurs, the expressions for the transient phase current mutation in the faulty and sound phases are analyzed. Then, the sampling process is segmented into several selection units (SUs) to form the MOHD-based faulty phase selection method. Additionally, the Hausdorff distance algorithm (HD) is used to calculate the waveform similarities of the transient phase current mutation among the three phases to form the HD-based faulty phase selection method. Finally, a practical resonant grounded distribution system is modeled in PSCAD/EMTDC, and the effectiveness and performance of the proposed method is compared and verified under different fault resistances, fault inception angles, system topologies, sampling time windows and rates of data missing.

Differential DC Component-Based Relaying Scheme for Transmission Lines

ABSTRACT Protection engineers and academicians are continuously working towards better relaying for modern transmission structures. This has become a requirement because transmission structure, nowadays, is being updated with new technologies, e.g. flexible AC transmission system devices. In this paper, it has been observed that the differential DC plays an important role in distinguishing the internal and external faults. A criterion is then developed based on this unique feature of the differential DC for the identification of faults in modern transmission lines. The performance of the proposed criterion has been tested with the help of simulation study carried out using EMTDC/PSCAD software for a variety of fault types with variations in fault location, fault resistance, fault inception angle, and compensation level. Furthermore, the performance of the proposed algorithm is also investigated for several rare conditions such as evolving faults, cross-country faults, noise in measurement, and measurement error. The results prove that the scheme is selective, accurate, and robust for uncompensated and series-compensated lines while it is accurate for low resistance faults in the case of a shunt-compensated line.

An FTU-Based Method for Locating Single-Phase High-Impedance Faults Using Transient Zero-Sequence Admittance in Resonant Grounding Systems

A novel fault location scheme using feeder terminal units (FTUs) for high-impedance grounding faults in resonant grounding systems (RGSs) is presented. The parallel resonance for a high-impedance fault (HIF) in an RGS with inverter-interfaced distributed generators (IIDGs) is analyzed. The process exhibits unique distribution features for transient zero-sequence components involving underdamped and overdamped states. We conclude that the transient zero-sequence admittances (TZSAs) from FTUs upstream of the fault point have the maximum value, while the TZSAs obtained from FTUs downstream of the fault point are small for HIFs. Therefore, the proposed location scheme uses FTUs to calculate the maximum values of the TZSA. By comparing with action criteria, the distribution automation (DA) master station utilizes the above results of each FTU to locate the faulty feeder section. The accuracy of the fault characteristics and the proposed method are validated by applying a real-time digital simulator (RTDS) and an FTU-based monitoring system. Additionally, the proposed scheme demonstrates an excellent and reliable performance, considering various faulty feeder sections, fault resistances, arcing faults, fault inception angles, imbalances and the presence of IIDGs and noise.

High impedance fault detection method for distribution networks under non-linear conditions

This paper presents a new high impedance fault (HIF) detection method considering the presence of non-linear loads in the distribution network. It adopts a cumulative error-based index to monitor the third harmonic phase angle, which is extracted with Stockwell transform and compared to a self-adaptive threshold for fault detection and classification. The proposed method requires only a single measurement device on the substation. Results show that the proposed method is able to quickly detect HIF in all simulated cases, considering several fault locations and different contact surfaces, not being affected by conditions such as fault inception angle, system loading percentage, or fault location. Additionally, results suggest that it can distinguish HIF from capacitor banks switching, low impedance faults, transformer energizing, and feeder energizing along with linear and non-linear loads switching. HIF real oscillographic records are also used for validation. The proposed method achieved a fast detection, in less than 11 cycles for most cases, and a high detection rate, over 99%, with no false positives.

Stockwell‐transform and random‐forest based double‐terminal fault diagnosis method for offshore wind farm transmission line

Due to the difficulty and time-consumption in locating short-distance transmission lines for deep-sea offshore wind farm (DOWF)，this paper proposes a novel double-terminal fault location method by using Stockwell-transform (ST) and random-forest (RF). After the fault type and branch are accurately determined, the accurate transmission line fault location is located. Firstly, Stockwell-transform is employed to extract fault eigenvalues from the collected wind turbine (WT) current signals, which will reduce the sensitivity of eigenvalues to noise. And the Pearson correlation coefficient (PCC) is introduced to remove duplicate eigenvalues. Secondly, the reserved fault eigenvalues are taken as inputs to the different random-forest to classify fault types and identify the fault branch, respectively. Finally, the double-terminal fault location principle is established in fault negative sequence network (only ABCG uses positive sequence components). Newton-Raphson method (NRM) is used to eliminate the influence of asynchrony data, which implies an accurate transmission line fault location for deep-sea offshore wind farm. More than 4000 fault cases data obtained by Simulink simulation verify the feasibility and performance of the proposed method. The results show that the proposed location method has a high fault recognition rate and is immune to fault inception angle, resistance, location and noise.

Fault identification in power cables by using travelling wave-based approach

Thefaults in the underground cables cause to generatetransients which propagate along the power cable as travelling waves. The velocity of the generated travelling wave and the time taken by a wave to reach the source point from the fault location enables us to calculate the fault distance value.In this paper a double endedtravelling wave based approach is used and a communication channel is designed to calculate the fault distance. A circuit-based model is developed in the EMTP-RV software to find out the fault distance from the source end for all types of faults. Further it is proved that the fault distance is unaffected by the change in ground resistance, various types of faults and the fault inception angle in the proposed method

Phasor-based fault location algorithm for three-end multi-section nonhomogeneous parallel transmission lines

In order to estimate the fault location on three-terminal multi-section mixed nonhomogeneous transmission lines, all the previously published algorithms utilize the synchronized voltage and current measurements at all ends. In this article, a fault location algorithm for three-terminal multi-section mixed double-circuit untransposed transmission lines is presented utilizing only unsynchronized current measurements. Considering issues related to the shunt capacitance, un-transposition of the line, and mutual couplings between all phases, a threshold free identification algorithm is developed to differentiate the faulted line branch. In addition, analytical fault location equation is deduced independent of fault resistance and fault type. The three-terminal power system is modeled using MATLAB environment, and several fault cases are conducted, including all fault types, different fault resistances and locations, as well as different fault inception angles. The introduced work shows high accuracy under the effect of measurement and synchronization errors as well as line parameters errors.

Experimental analysis of saturated core fault current limiter performance at different fault inception angles with varying DC bias

Economic growth has exponentially increased the power demand resulting in bulk power systems. The distributed generations are also integrating into the grid network to retrieve the benefits of the locally available generating resources. Also, the high-reliability expectations of supply systems lead to the interconnection of power networks. All these modern characteristics escalated the magnitude of short circuit currents in the grids. The security from these currents, therefore, challenged the power network protection systems. The deployment of the scalable and reliable Fault Current Limiter (FCL) technology can enhance the service span of existing components in the power industry. The Saturated Core Fault Current Limiter (SCFCL) can be a commercially viable solution to this problem. This paper reports the test performance of a scaled-down, compact, novel, copper-coils-based SCFCL model. The steady-state and transient-state behavior have been characterized in terms of saturation levels and the fault inception angles. The importance of DC bias selection in the optimum current limiting performance of the device is demonstrated in the results. The results also exhibit that the fault inception at the peak of voltage causes the most asymmetric transient during the current limiting process. Also, the heuristic design methodology based on extensive experimental work has been proposed, taking into account an application of optimum DC bias.

Comprehensive analysis of the fault inception angle influence in fault-induced traveling waves

This work presents a comprehensive analysis of the fault inception angle influence in the first wavefront of the fault-induced traveling waves (TWs) for all types of faults in a transmission line. The EMTP-ATP software simulated fault-induced TWs for all transmission line fault types considering the JMarti frequency-dependent transmission line model, whereas an emulated transmission line in an experimental setup generated fault-induced TWs of single line-to-ground faults for validating the effects of the fault inception angle. This work demonstrated that the energy of the fault-induced TWs changes with the fault inception angle according to a squared sinusoidal function, and pointed out the situations where there is no TW in each type of fault. Besides the support for a better understanding of fault-induced TWs, the analysis accomplished here will be essential for further development of TW-based detection, location, and protection methods.

Linear and Nonlinear Fault Location in Smart Distribution Network Under Line Parameter Uncertainty

The line parameters of the distribution network (DN) may change because of the atmospheric, structural, and operational conditions. The uncertainty of line parameters can compromise the accuracy of the automatic fault location methods. Besides, arc faults (AFs) may happen in the DN. These faults are difficult to locate in the faulty section because of the nonlinear, asymmetric, and random nature of AF current. In this article, we present a new time-domain fault location (TDFL) method to determine the location of the fault in smart power DN under the line parameters uncertainty. In the suggested method, line parameters' accurate values are determined using a mixed gradient descent particle swarm optimization algorithm. The suggested method's performance is investigated with the help of an IEEE 123-node test feeder in MATLAB (R2018b). The effects of parameter uncertainty, distributed generations operation conditions and modes, different types of AF, various fault distances, resistances, and the fault inception angles are studied. For further evaluation of the proposed method's robustness, two practical tests in the laboratory are carried out. The results confirm that the proposed TDFL method has high accuracy.

An accurate technique for supervising distance relays during power swing

Power swing is a power system transient phenomenon that arises due to several reasons including line switching, line outage, sudden increment or decrement in load, faults, etc. Unnecessary tripping during power swing and unnecessary blocking for faults occur during power swing result in distance relay maloperation. Several cascaded outages and major worldwide blackouts have occurred due to maloperation of distance relays. This paper proposes a technique for supervising distance relays during power swing. The proposed online technique discriminates real faults and power swing accurately. It relies on constructing a locus diagram for the current and voltage differences (∆I-∆V) between the two ends of the protected line. The locus is estimated at every power frequency cycle to continuously monitor the state of the line by utilizing the synchrophasor measurements at the sending and receiving ends of the line. The proposed technique is tested for two-area, four-machine power system under faults at different locations of zone-1 and zone-2 regions of distance relays, fault resistances, fault inception angles and slip frequencies using MATLAB software. The simulation results proved the superior improvement of distance relay performance for handling power swing blocking and unblocking actions.

A supervised principal component analysis-based approach of fault localization in transmission lines for single line to ground faults

Fault localization in power transmission line has been a key area of research, especially with the advent of modern soft computation-based digital relaying schemes. In this article, a principal component analysis (PCA)-based method of fault detection and localization in an overhead transmission line is proposed. The analysis is carried out for single line to ground faults only as these faults encompass about 70–90% among all the faults in transmission lines; although this generalized method could also be extended to cater other fault prototypes too. A fault in a line causes disturbances in the form of high-frequency transient oscillations which are developed immediately after the fault. The peaks and crests of these fault transients are investigated as key features from the receiving end three-phase voltage signals. These feature points are fed to a PCA-based fault localizer algorithm as supervised inputs. The proposed model is tested with a large set of fault signals, varying all the three major influencing parameters like fault locations, fault resistances as well as fault inception angle. Power system noise is also incorporated additionally in the fault signals order to incorporate more robustness to the localizer model. An average localization percentage error of 0.871% ranging from 0.011 to 2.413% is obtained from this work. The proposed work requires only a maximum of nearly 10.1% of post-cycle fault signal for analysis, which is remarkably less compared to several other schemes.

A fault location and detection technique for STATCOM compensated transmission lines using game theory

This study aims at proposing an original single-end protection scheme for the compensated transmission line using traveling waves and game theory. To this end, this paper initially investigates the effects of static synchronous compensator (STATCOM) on traveling waves passing through STATCOM installation point. Furthermore, based on the traveling wave theory, it evaluates the impacts of STATCOM's harmonic on conventional protections. A single-end method will be proposed in the next stage for fault protection on the compensated transmission lines with STATCOM. The extracted traveling waves in this study will be discriminated using the game theory, and discrete wavelet transform will be utilized to process the signals and assess the sensitivity of the proposed scheme considering the extraction techniques of the traveling wave. According to the obtained results, the proposed protection scheme is a reliable and accurate method for all possible faults type on compensated transmission lines at the various locations of the line and with different fault inception angles.

Fault Location in Overhead Transmission Lines Based on Magnetic Signatures and on the Extended Kalman Filter

This paper proposes a non-contact method for fault location in transmission lines, which is based on magnetic fields produced by current signals measured using magnetoresistive sensors installed only at transmission line terminals, under the phase conductors of the first transmission tower at both terminals or at the substations portals. The proposed method uses the Extended Kalman filter to process these measurements and is based on a travelling wave approach in order to perform the fault localization. This paper also describes the implementation and testing of the method, firstly introducing its overview, followed by an analysis of the magnetic fields produced by the current signals, as well as considerations on their measurement; secondly, detailing the Extended Kalman filter and the travelling wave approach; and, finally, presenting the results of the method with regards to simulations built using EMTP/ATP to evaluate its robustness under different conditions varying the fault resistance, fault inception angle, phases involved and fault location. The results indicate that the proposed method is robust and accurate.

Enhancing Distance Protection of Long Transmission Lines Compensated With TCSC and Connected With Wind Power

Thyristor controlled series compensation (TCSC) is widely used in long transmission lines to mainly improve power transfer capability. However, TCSC produces complicated impedance that negatively affects distance protection operation. The wind energy generation system produces additional complexity to the distance protection performance due to the variation of wind speed and fault current level. This paper proposes an integrated scheme to change adaptively the settings of the Mho distance protection by shifting the relay characteristics considering the bad impacts of TCSC, wind power and fault resistance. The proposed scheme achieves its main stages starting from fault detection, until relay tripping decision procedure including online estimation for preliminary fault location, impedance of TCSC and fault resistance using limited communication requirements. By extensive MATLAB simulations, the performance of the proposed scheme is examined compared with the conventional Mho relays under different fault locations, fault inception angle, fault resistance, different wind power penetration, different wind speeds and different TCSC firing angles. The achieved results ensured that the proposed scheme improves significantly Mho distance relay operation and avoids under-reaching and over-reaching problems irrespective of the large shunt capacitance along the transmission line, and also without identifying the parameters of TCSC such as the capacitance, the inductance or the firing angle.

Time-Domain Transmission Line Fault Location Method With Full Consideration of Distributed Parameters and Line Asymmetry

Accurate fault location reduces operating cost and outage time. This paper proposes a time-domain method to accurately locate faults in transmission lines, which only requires a very short data window (several milli-seconds) during faults. First, the voltage distribution through the line during faults is accurately obtained by solving the matrix form partial differential equations using the proposed numerical scheme. The proposed numerical scheme is mathematically validated for the transmission line fault location problem, with the optimal selection of time and distance intervals to ensure stability and minimum solution error. Afterwards, the fault location is obtained via the extremum value of the voltage distribution. The method fully considers distributed parameters as well as asymmetry of the line. Extensive numerical experiments validated that (a) the proposed numerical scheme demonstrates advantages towards other numerical schemes; (b) the proposed method presents higher fault location accuracy compared to the existing method, independent of fault types, locations and impedances; and (c) the fault location accuracy is not sensitive towards fault inception angles, loading conditions, measurement errors and parameter errors. The proposed method works with relatively low sampling rates (80 samples per cycle) and is compatible with IEC 61850 standard in present digital substations.

Neural Network Based Fault Detector and Classifier for Synchronous Generator Stator Windings (Dept.E)

This paper presents an application of multilayer feedforward neural network (MFNN) as a differential protection for synchronous generators. Two MFNN are designed, trained, and tested in this paper. The first one has two outputs which detect the internal and external fault state. The other neural network has four outputs to classify the faulty phases. The proposed neural fault detector and classifier were trained using various sets of data available from a selected synchronous model and simulating different fault scenarios (fault type, fault location, fault resistance and fault inception angle). The results show very good behavior of the MFNN and it was more reliable and accurate than conventional methods. It shows that MFNN offer the possibility to be used for on line synchronous generator protection and give satisfactory results.

Versatile relaying algorithm for detection and classification of fault on transmission line

This article presents a new and fast approach for detection and classification of the fault on a transmission line. The proposed method can effectively detect and classify a fault on a regular uncompensated transmission line. Moreover, the same can detect and classify faults when these lines are subjected to fixed series compensation, with the same accuracy and without any functional customization of the algorithm. Therefore, this method gets rid of the new setting requirement for the inclusion of series compensation. Vice versa can provide protection to a series compensated line during maintenance as well as in the eventuality of bypass of the compensator. This makes the developed algorithm versatile. The proposed algorithm normally converges for fault detection within half cycle from the fault inception, and requires no data after generating fault detection signal for fault classification; which enables the application of faster circuit breaking devices. The two-stage approach uses Wavelet Transform (WT) with Chebyshev Neural Network (ChNN) and uses only measured three-phase current signals at relaying end. The accuracy, speed, and effectiveness of the scheme have been verified with a fault data generation system developed on PSCAD/EMTP with different system parameter variations like fault resistance, load angle, fault inception angle, and types of faults. The results obtained show that the proposed scheme is accurate and fast as well.

Synchrophasor based fault location algorithm for three terminal homogeneous transmission lines

This paper presents a new fault location algorithm for three-terminal transmission lines, with the help of synchrophasor data. The algorithm utilizes the information of voltages and currents which are available from all the three ends. The proposed algorithm utilizes positive and negative sequence data for locating asymmetrical faults and only positive sequence data for locating symmetrical faults. The accuracy of the algorithm has been evaluated for various factors, such as fault inception angles, fault resistance, fault location, synchronization errors, measurement errors. The simulation of faults on the system have been carried out using PSCAD® and the algorithm is implemented in MATLAB software. Based on the simulation results it has been observed that the % error is less than 1.5% for 178 test cases out of 180, which shows 98.8% accuracy.