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Absrtact: Background: Nowadays, numerical relays configured through power swing blocking function are vulnerable to faults with high impedance owing to nonlinearities present in the faulty path. Identification of symmetrical high impedance faults incepting during the power swing scenario is of prime importance for protection engineers to avoid cascade tripping. It is analyzed that the classical approaches for symmetrical fault detection during power swing can mal‐operate owing to high level of uncertainty arise during validation of high impedance fault, symmetrical faults and cross country faults during power swing with varied level of compensation which has been explored in this research. Aims: This paper presents an innovative scheme for series compensated line by utilizing the capability of Relevance Vector Machine (RVM) as a disturbance classifier taking into consideration of cross country faults, CT saturation; power swings prone to symmetrical faults along with high impedance faults in comparison with prevailing methods. Materials & Methods: In order to validate the proposed RVM based disturbance classifier algorithm, different kinds of faults and power swing situations have been applied in IEEE 9 bus test system using PSCAD/EMTDC software followed by validation in MATLAB. The features of sequence components of currents are estimated using Modified Full Cycle Discrete Fourier Transform (MFCDFT). The extracted features are used as control inputs to RVM for discernment among power swing and fault under the influence of wide range of system and fault dynamics. Results: The developed RVM based disturbance classifier scheme generates a tripping signal in the event of high impedance fault during power swing and remains stable during swing conditions. It can be used in conjunction with an adaptive numerical distance relaying scheme for realizing complete protection of the power grid for all zones of protection. A comparative analysis with an existing disturbance classifier algorithm indicates relative superiority with much improved fault classification accuracy. Discussion: In order to validate the proposed algorithm, different kinds of fault and power swing scenario are realized in IEEE 9 bus test system using PSCAD and current samples are acquired at sampling frequency of 4 kHz. The phasor estimation of sampled signals has been performed using MFCDFT which is used to derive feature vector extraction from symmetrical components. The extracted features are applied to RVM based fault classifier algorithm for classification of disturbance. The obtained results are also compared with existing schemes of protections. It has been proved that developed algorithm outperforms with much improved fault classification accuracy. Conclusion: This paper discovers relevance vector machine based adaptive learning approach for dynamic disturbance classification in complex power grid network. The developed algorithm has been validated on IEEE 9 bus test system modelled in PSCAD. The fault and system dynamics are varied over a wider range which includes variation in fault type, fault impedance, fault inception angle, power flow angle, fault location and degree of line compensation level. Moreover, the validation of scripted algorithm has been performed for very complex power grid scenarios like cross‐country faults, high impedance faults with varying degree of compensation, power swing and saturation of instrument transformers etc. The feature vectors are extracted using MFCDFT and applied to supervised RVM based disturbance classifier and outperforms with classification accuracy of 99.74% which indicates it's superiority over existing classifier approaches based on SVM & ANN. [ABSTRACT FROM AUTHOR]

The traditional fault location methods are not effective for the multisource active distribution network and are difficult to meet both requirements of timeliness and fault tolerance simultaneously. In this paper, a fault location method for active distribution networks which combines both improved matrix algorithm and optimization algorithm is proposed. The improved matrix algorithm is constructed to determine the fault section hypothesis by using the causal relationship between the alarm information and the fault section. Subsequently, network splitting is used for causal verification to check whether the alarm information is distorted. If the alarm information is normal, the fault sections can be quickly located by the above matrix algorithm. If the alarm information is distorted, the optimization model is constructed by using the fault section hypothesis selected by the matrix algorithm. The discrete particle swarm optimization (DPSO) algorithm is used to solve this optimization model, which can accurately locate the real fault sections. Hence, the advantages of both matrix algorithm and optimization algorithm are complementary. Simulation results show that the proposed method has the advantages of both high timeliness and fault tolerance in a complex active distribution network. [ABSTRACT FROM AUTHOR]

Due to the overload limitation of the converters, the main protection for DC lines of High Voltage Direct Current based on Modular Multilevel Converter (MMC‐HVDC) requires ultra high speed for fault detection. The protection principles of single‐terminal traveling‐wave can meet this requirement. Such protection principles which are usually constructed by transmission theory of fault traveling‐wave have a clear physical concept and do not depend on boundary components. Almost all of these principles are dependent on accurately detecting the arrival time of the traveling‐waves. Thus, it is urgent to research a new time‐frequency analysis method with a high time resolution to identify the arrival time of traveling‐wave. This paper introduces Transient‐Extracting Transform (TET) to detect traveling‐wave and improves it fully considering the fault traveling‐wave characteristics of DC lines. The time resolution of improved TET is greatly increased and the arrival time of traveling‐wave is detected more accurately. Using the improved TET, a protection scheme for single‐pole fault based on the arrival time difference between aerial‐mode traveling‐wave and zero‐mode traveling‐wave is studied. The theoretical analysis and simulation results show that the performance of detecting traveling‐wave arrival time by the improved TET is higher than wavelet transform. Under the same fault condition, the time resolution of wavelet transform is only tens microsecond level. However, the time resolution of the improved TET increases to several microseconds. The accuracy of traveling‐wave detection by the improved TET is 95% higher than existing works. The simulation results also indicate that the single‐pole protection scheme using the improved TET can accurately distinguish between internal faults and external faults. There is a better ability to resist fault resistance for the protection scheme, and it is not affected by DC boundary elements. [ABSTRACT FROM AUTHOR]

This paper proposes a novel approach for fault detection, classification, and distance estimation of five kinds of faults (ie, cable and Arc faults) in the PV‐based DC‐ring microgrid. The proposed approach is based on the Hilbert Huang Transform (HHT) and online sequential random vector functional link network (OS‐RVFLN). Initially, differential current signals are passed through empirical mode decomposition (EMD) to yield intrinsic mode functions (IMFs). Among the series of IMFs, more efficient IMFs are selected based on the threshold of maximum weighted kurtosis index (M‐WKI) value for fault diagnosis. The selected IMFs are passed through Hilbert transform (HT) for determining the instantaneous frequency, magnitude spectrum, and Hilbert energy. Then, the Teager energy operator (TEO) is applied to the more effective IMF among the selected IMFs of each DC fault for fault detection. The most suitable target features are extracted from the selected efficient IMFs. This feature set data is initialized to the proposed HHT‐OSRVFLN algorithm for five kinds of faults classification and its location estimation. The performance of the proposed algorithm in the proposed microgrid is proved in terms of low fault detection time, superior classification accuracy, and low relative error through different case studies by consuming minimum computation time in MATLAB/Simulink environment. Finally, the digital architecture of the proposed method is designed and simulated in Xilinx ISE 14.5 software environment to estimate the fault location. The Chip scope hardware debugging output proves the correctness, simplicity, feasibility, practicability, and robustness of the proposed method for online fault diagnosis. [ABSTRACT FROM AUTHOR]

Summary: The deployment of distributed energy resources (DER) theoretically improves the reliability of a radial distribution system by taking advantage of the ability to island DERs and customers. However, an isolation device has to be placed in order to create this "island." On the other hand, a radial distribution system typically lacks isolation devices that are able to detect and isolate a fault, especially on the main distribution feeder, which is nowadays often protected by the substation breaker. This paper proposes a methodology to identify the optimal locations to install isolation devices in a radial distribution network with DER integrations, aiming at reliability improvements of distribution networks. We exploit utility historical load and fault data for generating multiple fault scenarios and develop a stochastic programming‐based optimization model for unserved energy minimization. Two case studies on an IEEE 4‐bus and 123‐bus systems are performed, including some sensitivity analysis. [ABSTRACT FROM AUTHOR]

Summary In this paper, a communication‐based selective protective scheme using the combined adaptive cumulative sum algorithm (CACUSUM) is proposed, which can be used in wide‐area protection of multi‐terminal high voltage direct current (MT‐HVDC) transmission lines. The proposed algorithm works in the time domain and uses the variation pattern of the magnitude of line currents and bus voltages for fault detection. Simulation is done in MATLAB program using a test four terminals meshed HVDC transmission system. As a robust fault detector, the proposed approach detects fault occurrence as well as determining faulty zone, either faults on the DC line or AC part of the HVDC system; the whole in less than 2 ms. Simulation results confirm the robustness of CACUSUM performance against different fault resistances and different fault locations as well as the presence of noise in the signals. Appropriate speed, adaptivity, independence from system parameters, low sampling rate, low computational burden, simplicity, no need for any complicated hardware, and ability to detect cross faults are the significant benefits of this method in comparison with other ones. [ABSTRACT FROM AUTHOR]

Summary: Integration of a series capacitor in a transmission line not only has advantages such as system stability and power factor improvements, voltage profile regulation, and power flow maximization but also shows some unwanted effects such as current and voltage inversion, change in line impedance, and subharmonic frequency that leads to mal‐operation of the conventional protection scheme. This paper introduces a fault detection method for a series‐compensated line. An algorithm is proposed that uses the extracted DC component of currents at both sending and receiving ends to detect the fault and generate a trip signal. The proposed protection criterion is successfully examined for diversified (adverse) conditions using PSCAD/EMTDC simulations. [ABSTRACT FROM AUTHOR]

Summary: This paper studies the identification of special load current in a Metro DC traction system. Because of the widespread application of variable voltage variable frequency (VVVF) used by electric vehicles and regenerative braking technology with energy feedback, the DC traction power system becomes a second‐order nonlinear dynamic system, whose structure may become unstable during the regenerative braking of vehicles. Divergent low‐frequency oscillation current often appears in DC traction system. Engineering practice proves that the divergent oscillation current belongs to abnormal load current with short duration, and it is not a fault current, but its amplitude and slope are similar to the terminal short‐circuit current, which is easy to cause DDL nuisance tripping. This shows that the di/dt and ΔI protection (DDL protection) principle needs to be further improved and optimized. In order to identify the short‐circuit of a traction electrification system (TES) quickly and accurately, a compensation algorithm is proposed by the correlation dimension of chaos theory. The correlation dimension can reflect the dynamic change of the differential current signal of TES quickly and sensitively, which can effectively identify short‐circuit and special load current. Real‐time simulation and fault measurement based on closed‐loop system show the effectiveness of the method, which can be used as the compensation algorithm for the feeder protection algorithm of the DC traction system to improve the safety and reliability of Metro DC feeder protection. [ABSTRACT FROM AUTHOR]

Faults in electrified railway grounding grids can lead to significant surface potential rise, which threatens railway transportation and operation security. In order to efficiently diagnose the grounding status of the grounding grid and locate the fault location, this paper firstly presents the development of a mathematical model to reveal the earth surface potential distribution of grounding grids. Furthermore, a simulation model is built specifically for this study using CDEGS software to calculate the earth surface potential distribution of grounding grids under fault conditions. The simulation model has been used to validate the developed mathematical model by a comparison study. Finally, an intelligent algorithm based on grey incidence degree and fuzzy theory is proposed. This algorithm facilitates the fault condition diagnosis and the fault conductor position location. Using the fault condition data calculated by the simulation model, a few common grounding grids' fault conditions are diagnosed and located effectively by the proposed method. The results identify that the proposed method can ensure the safe operation of the traction substation. [ABSTRACT FROM AUTHOR]

Fast and accurate fault location methods will accelerate power system restoration process and then cause improvement on availability and reliability indices. Presenting a modified scheme in order to improve accuracy of impedance-based fault location method in electric power distribution systems (EPDS) equipped with distributed generation (DG) units is the main goal of this paper. To achieve this goal, an iterative algorithm is introduced to compensate load variations. Also, a method is presented based on forward/backward sweep load flow to consider loss in all laterals of EPDS. Then, fault location will be determined by using a comprehensive method that extracts a fifth-order algebraic equation for each type of fault. This method will be modified to consider the presence of DGs in EPDS. In this paper, all the specific characteristics of real distribution systems such as unbalanced nature of network and loads, different types of loads, presence of multi-phase laterals, and capacitive effects of distribution lines are taken into account. The proposed scheme uses only 1 measurement unit at the main substation and 1 measurement unit at the DG bus. In this paper, modified IEEE 34 node test system is simulated by using PSCAD/EMTDC software, and it is used as a test system to evaluate the performance of the proposed method. Different scenarios such as the effect of fault distance, fault type, different fault resistances, and measurement unit errors are evaluated. The results indicate usefulness and precision of the proposed scheme. [ABSTRACT FROM AUTHOR]

The transmission line fault location algorithms are affected in presence of FACTS device like unified power flow controller (UPFC) due to changed voltage and currents signals at the relaying point after occurrence of fault. Additionally, these algorithms involve high computation burden associated with signal processing techniques and are proven to be in‐efficient during severe power system conditions. To eliminate the limitations stated above, a novel travelling wave aided intrinsic time‐decomposition (ITD) based fault location algorithm is presented in this paper for estimation of fault location in UPFC employed transmission lines. ITD offers several advantages over other time‐frequency‐energy (TFE) analysis tools such as presenting precise temporal information and involving less computation burden. ITD decomposes a given signal into a sum of proper rotation components (PRCs) followed by a monotonic trend. The proposed ITD based fault location algorithm estimates the arrival times of travelling waves from first PRC of modal voltage signals of the terminals to which the transmission line is connected. From the estimated arrival times, the fault location is calculated. For simulation, a 100 MVA UPFC controlling the power flows in a 500 kV transmission system is used. Different cases of faults with diverse power system conditions are applied to examine the robustness and efficacy of ITD based fault location algorithm. Further, ITD base method is compared to existing methods available in literature and found to be a better performer in the context of fault localization. [ABSTRACT FROM AUTHOR]

Summary: In the modern power system, the fault identification and classification is one of the challenging tasks during high fault impedance due to low change in the magnitude of fault current from steady‐state to fault inception. In this paper, a high impedance fault detection technique is proposed based on Hilbert‐Huang transform (HHT). The energy for each phase is computed from the intrinsic mode function (IMF) of three‐phase voltage/current signals. An average relay energy index (AREI) is proposed to detect the transmission line fault in the large interconnected power system. Furthermore, a fault classification technique is also proposed based on relay energy index (REI) of each phase of the three‐phase voltage/current signals. The proposed HHT based fault detection technique is validated on standard WSCC 9 bus and IEEE 14 bus test power systems using PSCAD and MATLAB software. The simulation results reveal that the proposed Hilbert‐Huang transform based fault identification and classification technique can be best suitable for protection of transmission lines during high impedance faults in complex and large AC power transmission system. [ABSTRACT FROM AUTHOR]

Summary: This paper presents an algorithm for optimal placement and sizing of energy storage systems (ESSs) to enhance the reliability of a radial distribution system employing teacher learning‐based optimization (TLBO) method. The location and size of ESSs have great impact on system reliability. However, the number of placed ESSs increases the overall cost of the system. Hence, the algorithm is designed to minimize the objective function of problem, which includes cost of energy not supplied (CENS), an additional cost such as investment cost and operational cost of ESSs (life cycle cost), and power loss due to line flows in distribution system. The proposed algorithm utilizes the TLBO method to minimize the objective function. To assess the performance of the algorithm, IEEE standard 30‐bus radial distribution system has been considered. The optimal location and size of ESSs have been obtained by considering various case studies. Subsequently, comparative performance analysis is done on results obtained by using TLBO, particle swarm optimization (PSO), differential evolution (DE), and genetic algorithm (GA). Furthermore, rigorous analysis is performed by imposing limit on number of applied ESSs and by varying the maximum capacity of participating ESSs. Lastly, the application of proposed method for placement of ESSs in IEEE 69‐bus distribution system provides 17% reduction in total cost of operation. [ABSTRACT FROM AUTHOR]

Summary: Selective phase tripping during unbalanced short‐circuit fault helps in improving the reliability of the smart distribution systems. Selective phase tripping demands correct identification of faulted phase(s). The existing practices fail to identify the faulted phase(s) correctly in smart grids that include inverter‐interfaced distributed generators (DGs), such as wind and solar photovoltaic (PV) DGs. This paper presents a fault‐detection and faulted‐phase(s)‐identification scheme for smart distribution systems installed with both synchronous and PV distributed generators. In this work, the transient energies derived from the superimposed components of the measured voltage and current signals at both ends of a feeder are utilized for accomplishing the fault‐detection and faulted‐phase(s)‐identification task. The performance of the proposed method is evaluated for numerous fault and nonfault cases generated on three different test systems through power system computer aided design/EMTDC at different system operating modes and topologies. Fast response time (less than one cycle), low computational burden, and relatively high accuracy compared to the existing methods justify the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, a new method is proposed for fault location using minimum number of phasor measurement units (PMUs) in a power network. In this method, all possible fault points over transmission lines are represented as virtual buses, and corresponding bus impedance matrices are calculated. Because capacitive property at the virtual buses is neglected, resulting impedance matrices are linear with respect to fault point distance. Using voltage data provided by PMUs and applying superposition theorem, potential fault points on every single transmission line are extracted, each by solving linear equations, and then, exact fault location is obtained using two predefined rules. In addition, fault type and fault impedance are determined by some criteria involving symmetrical components. Merits of the proposed method include simplified equations, thanks to linearity provided by omitting capacitive effect, as well as minimum required PMUs to be installed in the network. Besides, a set of fundamental rules describing PMU placement constraints, according to required voltage data of different points in the network, are introduced. Employing these rules ends up to a fewer number of required PMUs in comparison with other proposed methods. At the end of this paper, the accuracy of the suggested method has been evaluated by applying it on three test systems, namely Institute of Electrical and Electronics Engineers (IEEE) 30-bus, IEEE 39-bus, and IEEE 118-bus. Simulations, performed by MATLAB Simulink (MathWorks, Natick, MA, USA), indicate high accuracy and consistent results of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: This paper describes sensor fault control (SFC) scheme for a wound rotor induction generator (WRIG)‐based wind energy system (WES) connected to a standalone DC micro grid (DCM). The DCM provides excitation for WRIG through a rotor side converter (RSC). The stator voltage and frequency are regulated using PI controllers. The generated power is supplied to loads, and excess power is supplied to DCM by PWM rectification operation of RSC. During stall mode, DCM supplies load through RSC by PWM inversion operation. To execute a smooth changeover of modes, supervisory control algorithm is employed. The control scheme involves sensors which may not be ideal and if fault occurs might lead to system collapse. To compensate the electrical sensor faults, a fault detection and compensation (FDC) scheme based on adaptive neuro‐fuzzy inference system (ANFIS) is employed. For compensating mechanical sensor faults, an electrical sensor is employed. The system is experimentally tested to show the effectiveness of SFC scheme. [ABSTRACT FROM AUTHOR]

In this paper, an effort is being made to develop a fault diagnosis algorithm using Duval triangle method of dissolved gas analysis (DGA) as a backbone for more reliable fault diagnosis. The algorithm is based on integrated model which is the fusion of Duval triangle and IEC ratio method. It uses the conventional Duval triangle rules to detect dominant faults and IEC method rules to detect 'no' and boundary faults. Hence, the proposed method simultaneously checks the normal operating conditions, boundary and dominant fault cases. A graphical-user interface (GUI) has also been prepared using LabVIEW. Study of fault severity is also carried out for various Duval triangle zones. Fault severity is determined using concept of energy weighing, and fuzzy model has been developed for the same. The system has been tested using a fault database and shows accuracy of 93.6%. Results presented indicate a trend towards a more reliable system. [ABSTRACT FROM AUTHOR]

This paper suggests a modification in symmetrical component (SC) method, used for characterization and classification of voltage sags, by incorporating an angle, ɸ, in it. The ɸ is considered as an angle between drop in positive-sequence voltage components, associated with single line-to-ground and line-to-line faults. The modified formula is tested on two data sets of real power systems and compared with the SC method. The results suggest that this modification offers advantages of giving accurate comprehensive information on the nature of (i) voltage sag, (ii) associated fault, and (iii) faulted buses, simultaneously. This study aims to establish a precise characterization method for voltage sags due to faults in low-voltage resistance-grounded distribution systems (LVRGDS), as their more frequent occurrence and vulnerability of economic impacts to industrial customers than the shallow voltage sags due to faults in high-voltage solidly grounded transmission systems (HVSGTS). For this, the variations in φ, for different fault locations in LVRGDS and HVSGTS, are evaluated, resulting in large values of φ in LVRGDS. These larger values of φ establish better characterization capability, for voltage sags in distribution systems, with the proposed method than the SC method. Also, the capability of φ to identify the behavior of un-faulted phase voltages has been revealed. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

With the development of wide-area measurement technology, it is possible to synchronously obtain the traveling waves from different measuring points in a complex power grid. Considering fault-generated traveling wave transmits along the shortest path in the power grid and timestamps of wave fronts can be acquired by phase-mode transformation and wavelets, this paper proposes an optimal deployment scheme of traveling wave recorders (TWR) in the power grid based on the extended double-end fault-location method. Then the fault-location methodology is presented. It is critical to guarantee that the double-end method is applied to the power grid and recognizes the specialized measuring combinations preciously and quickly, and the fault can be located consequently wherever it occurs. At last, fault-location accuracy is improved by the correction approach. All simulations are carried out in PSCAD/EMTDC, and the proposed procedure is applied to the IEEE 30& 57-bus test system to exam its validation. The results show that it can accurately locate a fault with 13 TWRs in IEEE 30-bus test system and 16 TWRs in IEEE 57-bus test system, and absolute error is less than 20 m. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, an accurate method is presented for fault locating in transmission lines by using a simple instance-based learning algorithm. Features of patterns are adopted on the basis of harmonic spectra extracted by applying the S-transform on only voltage signals measured at one terminal of line. Due to distinct spectral patterns of transients induced by different types of faults, short circuit faults are divided into the first category including single-line-to-ground and double-line faults, and the second category including double-line-to-ground, three-line, and three-line-to-ground faults. Then, by relying on flexibility of the utilized learning method, a separate fault-location algorithm is proposed for each fault category. Furthermore, for the first category of faults, a method is provided to identify voltage signals with insufficient harmonic content for distinguishing between reliable and unreliable fault-location results. The accuracy and performance of the proposed method is validated by fault locating in the New Zealand Lower South Island system. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes a fault location estimation method for distribution networks considering errors from measurement devices. The method determines the fault location based on the voltage sag and current magnitudes. The fault location is based on faulted section and fault distance measured from one end of the bus. Faulted section is determines by matching the measured voltage and current with a pre-developed data. For multiple faulted sections, ranking analysis is employed to rank the most likely faulted section. Fault distance is calculated from one end of the identified faulted section. By determining the faulted sections, a fault in homogenous and non-homogenous networks can be located. The method has been tested using an actual Malaysian 11 kV distribution network. Different values of measurement errors have been applied, which includes positive and negative values. The test results showed the effectiveness of the method under various uncertainty of error from measurement devices. The proposed method can serve as an alternative technique for estimating fault location in distribution networks. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a new double-end fault locator is presented for transmission lines. The fault location is achieved using synchronized measurement data and applying the least error squares (LSQ) principles disregarding the line parameters. The LSQ is applied on the positive sequence equivalent circuit to locate the fault distance. The proposed algorithm is non-iterative and simple as it is derived from the lumped parameter fault locator model. Due to using double-end data, the algorithm provides promising performance against the fault resistance and untransposed transmission lines. Furthermore, as it is derived using the positive sequence network only, it is suitable for locating any fault type. When the algorithm is evaluated for long overhead transmission system, its accuracy is found acceptable up to 220 miles because of double-end measurements. The ATP-EMTP program is used to perform the fault cases and therefore evaluating the locator performance. The test results provide evidence the efficacy of the proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Power Distribution System (PDS) is spread on different places. Therefore, PDS has many laterals and load taps. Accurate fault locating in PDS causes to improve reliability indices and its efficiency. In this paper, an improved method is suggested for fault location in PDS, which has a high accuracy. In the proposed algorithm, by using phase domain of distributed-parameter line model, a fifth-order algebraic equation of fault distance is obtained, which can improve the accuracy of determined fault distance for all types of faults. The proposed method is tested under different fault resistances in which the results show low sensitivity to this parameter. To evaluate the accuracy of the proposed method, the modified IEEE 34 Node Test Feeder is used, and its efficiency and accuracy is proved. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: An unprecedented growth of nonlinear load in recent decades has led to significant change in the power profile of modern distribution systems, which requires a modified approach for quantifying non‐sinusoidal power. Analysis of distribution system becomes even more challenging when voltage harmonics are also present in the substation bus besides nonlinear load. In this paper, a comprehensive distribution load flow algorithm for distorted and unbalanced radial distribution systems has been proposed. The methodology involves the computation of voltage and current distortion at each bus of the radial distribution system (RDS) to quantify various distortion power terms. Main contribution of the paper is to assess the increase in total power and overloading of shunt capacitors for various harmonic orders in the distorted distribution system. The proposed method has been tested on two IEEE distribution systems having current and voltage distortions. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we study the significance of the impact of grid structure on first swing dynamics. Particularly, the dynamics are characterized with the total transient energy injected into the power system during the fault period. Two methods are used to evaluate the total transient energy. One method is to use the representation of the total transient energy in terms of grid‐structure‐related variables, and the other method is to use time domain simulations. In a real power system, we investigate the correlation between the total transient energy predicted using the structural representation and the one evaluated using time domain simulation with various scenarios taking into account different generator models, load models, and operating conditions. It is found that there is a strong correlation between the evaluation results using the two methods, and the strong correlation does not change significantly with generator models, load modes, and operating conditions. Moreover, we further quantitatively analyze the discrepancy of the evaluation results obtained by the two methods. It is found that the discrepancy is small for most critical fault locations. The structural representation is useful for fast screening potential critical fault locations in large‐scale power systems. The findings can be considered as a manifestation of the significant role of grid structure in characterizing first swing dynamics. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a new probabilistic model for active low‐voltage prosumers suitable for distribution expansion planning studies. The load uncertainty of these consumers is considered through a range of load profiles by segmenting the energy consumption according to the different energy uses. Then, consumption adjustments are simulated using a nonhomogenous Poisson process based on the energy usage preferences and the financial gains according to the tariff scheme. A case study based on the modified IEEE 33‐Bus test system with real data collected from a Brazilian distribution company is performed in order to analyze the impact of the load profiles in scenarios with high penetration of renewable distributed generation (DG). The experiments carried out reveal that considerable monetary savings in the expansion of the distribution grid can be achieved for this case study (up to 37%) as compared with the alternative with no active demand (AD) by exploiting the flexibility associated with the active behavior of prosumers as a response to price signals and/or by permitting adequate levels for the integration of DG into the distribution grid. [ABSTRACT FROM AUTHOR]

Summary: This paper introduces a new fault location technique for two‐terminal four‐circuit series‐compensated untransposed transmission line utilizing synchronized phasor measurements. The proposed technique is formulated based on theory of transmission lines and Taylor series expansion of distributed parameter line model considering the mutual couplings between the parallel lines. The technique does not require the fault type and the equivalent impedance model of metal‐oxide varistor (MOV) and series capacitor. Firstly, two subroutines are derived to determine the true fault location assuming that the fault occurs on both sides of the series compensator (SC). After that, the true fault location is selected based on the fact that the equivalent impedance of the SC must have resistive and capacitive components. A 500‐kV system with four‐circuit series‐compensated line is simulated in DIgSILENT Power Factory software while the fault location calculations are implemented in MATLAB. The proposed technique is investigated under different fault resistances and locations as well as all fault types including inter‐circuit faults. In addition, the effect of complex fault impedance, variation of earth resistivity, synchrophasors errors, and errors in line parameters is checked. The simulation study assures the validation of the technique for all simulated fault cases. [ABSTRACT FROM AUTHOR]

Summary: This study presents a method for optimally selecting the location and size of switched shunt capacitors equipped with stand‐alone voltage control systems and fixed shunt capacitors in radial distribution networks. The main contribution of this paper is the introduction of a novel algorithm specifically designed for placement of capacitors equipped with stand‐alone voltage control systems. The considered objective function is the net saving calculated for every potential solution by using a backward‐forward load flow technique. A genetic algorithm is used to maximize the objective function while taking into account the technical constraints of the distribution network and the maximum capacitors' sizes depending on the set points of the stand‐alone voltage control system and on the locations of capacitors. The effectiveness of the proposed optimization method is verified and compared with other prevalent methods by simulation results carried on 69‐bus and 28‐bus distribution networks with three load levels. [ABSTRACT FROM AUTHOR]