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Aiming at the problems of low equipment utilization and the high-capacity requirements of existing arc-suppression devices, a multi-functional reactive power compensation device with the capability of grounding fault regulation (MF-RPCD) is proposed. Firstly, the topology and operation mechanism of MF-RPCD are introduced in this paper. MF-RPCD works in a reactive power compensation mode when a power grid is under normal operation to ensure the unit power factor operation of the power-grid side. When a single line-to-ground fault occurs in the power grid, MF-RPCD works in a fault-regulation mode to effectively suppress the ground-fault current. Secondly, the parameters of the active and passive parts of MF-RPCD are optimally designed to ensure the stable operation of MF-RPCD. Finally, the correctness, feasibility and effectiveness of the proposed topology and functions are verified using simulations and experiments. [ABSTRACT FROM AUTHOR]

Aiming at the problems of low equipment utilization and the high-capacity requirements of existing arc-suppression devices, a multi-functional reactive power compensation device with the capability of grounding fault regulation (MF-RPCD) is proposed. Firstly, the topology and operation mechanism of MF-RPCD are introduced in this paper. MF-RPCD works in a reactive power compensation mode when a power grid is under normal operation to ensure the unit power factor operation of the power-grid side. When a single line-to-ground fault occurs in the power grid, MF-RPCD works in a fault-regulation mode to effectively suppress the ground-fault current. Secondly, the parameters of the active and passive parts of MF-RPCD are optimally designed to ensure the stable operation of MF-RPCD. Finally, the correctness, feasibility and effectiveness of the proposed topology and functions are verified using simulations and experiments.

The further identification of fault types for single line-to-ground faults (SLGFs) in distribution networks is conducive to determining the cause of grounding faults and formulating targeted measures for hidden danger treatment and fault prevention. For the six types of SLGFs generated in the actual power grid, this paper deeply studies their fault characteristics. Firstly, the classification criterion of fault transition resistance is derived by the generation mechanism of fault zero sequence voltage (ZSV). At the same time, by comparing and analyzing the same and different characteristics between faults, three criteria for fault classification are obtained. Based on the above four criteria, a multilevel and multicriteria fault classification method is proposed to judge six types of SLGFs. Then, the proposed method is verified by various fault state simulations of the distribution network model with a balanced topology and unbalanced topology. The engineering application of the method is demonstrated by the verification of actual power grid data. Finally, noise and data loss interference test results show the robustness of the method. [ABSTRACT FROM AUTHOR]

The further identification of fault types for single line-to-ground faults (SLGFs) in distribution networks is conducive to determining the cause of grounding faults and formulating targeted measures for hidden danger treatment and fault prevention. For the six types of SLGFs generated in the actual power grid, this paper deeply studies their fault characteristics. Firstly, the classification criterion of fault transition resistance is derived by the generation mechanism of fault zero sequence voltage (ZSV). At the same time, by comparing and analyzing the same and different characteristics between faults, three criteria for fault classification are obtained. Based on the above four criteria, a multilevel and multicriteria fault classification method is proposed to judge six types of SLGFs. Then, the proposed method is verified by various fault state simulations of the distribution network model with a balanced topology and unbalanced topology. The engineering application of the method is demonstrated by the verification of actual power grid data. Finally, noise and data loss interference test results show the robustness of the method.

When a single line-to-ground fault occurs in the ungrounded distribution system, the steady-state fault current is relatively small for fault analysis and the transient fault current is observable, which can be used for faulted feeder identification and location. The principal frequency component retains most of the characteristics of the transient current. The principal frequency is related to the distance from the fault point to the substation and can be used for fault location. This paper analyzes the sequence network model of a single line-to-ground fault in the distribution network, and gives a method for principal frequency calculation. Depending on the characteristics of the maximum amplitude of the principal frequency component of the faulted feeder, the method of faulted feeder identification is given. Based on the complementary characteristics of the phase angle of the principal frequency component of the fault current and the phase angle at the substation bus, the faulted section location is carried out. MATLAB simulation is used to verify the effectiveness of the faulted feeder identification and location method.

As for a single line-to-ground fault in an ungrounded distribution system, the power-frequency current is too low to detect the fault. The transient current is more palpable than that at a power-frequency of 50 or 60 Hz. It is an effective method to estimate the fault using the transient fault current. To analyze and calculate the transient current of single line-to-ground faults, an equivalent circuit is proposed in this paper. This model is based on distributed parameters of power lines. And it contains positive, negative and zero sequence information. The transient equivalent circuit consists of equivalent resistance, equivalent inductance and equivalent capacitance. And the method of calculation the equivalent ele- ments is also submitted.MATLAB simulation results showthat the newtransient equivalent circuit has higher accuracy and stronger adaptability compared with the traditional one.

The measurement of the line impedance in long lines is adversely affected by fault and system parameters such as, the type and location of the fault, fault resistance, short circuit MVA of the source (presence of weak source), power transfer angle etc. This paper proposes a new technique to measure the line impedance during fault condition accurately, considering wide variations in the aforementioned variables. It is based on the mathematical analysis of the sequence network diagram of a non-homogeneous 400 kV, 50 Hz double infeed line, considering a single line-to-ground fault. Instead of using voltage and current vectors for the analysis, the impedance vectors are used to calculate the new impedance seen at the time of fault. The technique is verified using MATLAB/SIMULINK software. The simulation results conclude that the new measuring technique is precise, simple to understand, and rigid to the changes in all the system and fault parameters considered in this paper. [ABSTRACT FROM AUTHOR]

Root-cause identification of faults in a distribution network is conducive to fault inspection as well as reducing injuries and damage. In this article, a novel method based on correlation dimension and average resistance is proposed to identify the root cause of permanent single line-to-ground fault in urban small current grounding systems. First, the reliability of the grounding fault and whether the fault occurred on a dry or wet surface can be identified by the correlation dimension. Then, the average resistance of the fault is used to classify the specific root cause, including wet land, dry land, wet concrete, dry concrete, and water. Experimental results show that this method can realize the classification of root causes and is robust to sampling rate, harmonics, and line impedance. [ABSTRACT FROM AUTHOR]

Faulted line detection is a key step of intelligent fault diagnosis of distribution systems, laying the foundation for the further fault location and service restoration. A novel single line-to-ground (SLG) faulted line detection method based on the feature fusion framework is proposed. In the proposed framework, one-dimensional convolutional neural network is employed as a powerful tool to extract more effective features. In addition, there is an imbalance phenomenon between data of the faulted line and healthy lines when a data-driven model is used in the faulted line detection. The proposed framework offers an avenue for overcoming it and improves the accuracy of detection. Considering the limited data of SLG faults in actual power systems, prior knowledge of SLG fault detection is integrated into the data-driven model, which proves useful in reducing dependence on the training data quantity. The experiments verified the superior performance of the proposed feature fusion framework-based method. [ABSTRACT FROM AUTHOR]

The power requirements of grids have risen as artificial intelligence and electric vehicle technologies have been used. Thus, the installation of distributed generators (DGs) has become an essential factor to streamline power grids. The objective of this study is to optimize the capacity and location of DGs. For this purpose, an objective function was defined, which takes into account the fault current and the levelized cost of energy, and a modified particle swarm optimization method was applied. Then, we analyzed a case of a single line-to-ground fault with a test feeder (i.e., the IEEE 30 bus system) with no DGs connected, as well as a case where the DGs are optimally connected. The effect of the optimally allocated DGs on the system was analyzed. We discuss an optimal layout method that takes the economic efficiency of the DG installation into account.

We developed an International Electrotechnical Commission (IEC) 61850-based centralized protection scheme to prevent single line-to-ground (SLG) faults in the feeders and busbars of ungrounded distribution systems. Each feeder intelligent electronic device (IED) measures its zero-sequence current and voltage signals and periodically transmits zero-sequence phasors to a central IED via a Generic Oriented Object Substation Event message. Using the zero-sequence phasors, the central IED detects SLG faults in feeders and busbars. To achieve centralized protection, angle differences between the zero-sequence currents and voltage phasors are exploited, and their calculation compensates for data desynchronization. The feeder IEDs were implemented using the MMS-EASE Lite library, while the transmitted zero-sequence phasors were calculated based on fault signals simulated by Power System Computer Aided Design / Electro-Magnetic Transient Design and Control (PSCAD/EMTDC). The central IED determined if the SLG fault was in a feeder or busbar by aggregating and analyzing the zero-sequence phasors received from the feeder IEDs. The results confirmed the validity and efficiency of our centralized protection scheme.

• A novel hybrid arc suppression device for single line-to-ground faults is proposed. • Costs and performance are comparison with existing methods in detail. • The effectiveness and the robustness are analyzed from various aspects. Traditional passive arc suppression devices (ASDs) do not provide complete compensation for single line-to-ground (SLG) fault currents. Meanwhile, active ASDs are expensive. This study proposes a novel hybrid ASD to balance compensation and cost. The hybrid ASD consists of a passive part and an active part. To reduce the fault voltage to near zero, the passive part uses a single-phase isolating transformer and two sets of phase-selection switches. The active part, which compensates for the residual voltage caused by the transformer's leakage impedance, is connected to the secondary side of the transformer and the ground using a small-capacity inverter. A model predictive control (MPC) method is employed as the controller. We conducted simulations and experiments for various SLG fault cases, which demonstrated the effectiveness and robustness of the hybrid ASD in arc suppression. The hybrid ASD that we propose is independent of the neutral point and has several advantages, including low cost, strong arc suppression capabilities, and high robustness. [ABSTRACT FROM AUTHOR]

This paper proposes a protection method for single line-to-ground (SLG) faults in an ungrounded offshore wind farm with fully-rated converter-based wind turbines. The proposed method uses the unsynchronized current phasors measured by unit protections installed at the connection point of the fully-rated converter (FRC)-based wind turbines (WTs). Each unit protection collects the unsynchronized current phasors from two adjacent nodes and synchronizes them by aligning the positive-sequence current to the same phase angle. The faulted section is identified by comparing the phase angles of the synchronized zero-sequence currents from adjacent nodes. Simulations of an ungrounded offshore wind farm with relay models were carried out using power system computer-aided design (PSCAD)/electromagnetic transients including direct current (EMTDC). [ABSTRACT FROM AUTHOR]

Power distribution systems play important roles in modern society. When distribution system outages occur, speedy and precise fault location is crucial in accelerating system restoration, reducing outage time and significantly improving system reliability, and then improves the quality of services and customer satisfaction. In this paper, we propose a reduced algorithm utilizing the sum of sending-end currents of the three phases to calculate the fault current, and therefore, avoid the iterative aspect of the classic algorithm for single line to ground fault location and reduce its computational charge. The test results are obtained from the numerical simulation using the data of a distribution line recognized in the literature. [ABSTRACT FROM AUTHOR]

Abstract—The work presented in this article addresses the problems encountered by the conventional digital distance relay used for the protection of transmission lines fed from one end. To observe its behavior during a high-resistance single line-to-ground fault, a laboratory prototype of a three-phase transmission line using equivalent power system components has been developed by the authors. Thereafter, a new digital distance relaying algorithm is presented for the compensation of errors produced by the conventional digital distance relay during a high-resistance single line-to-ground fault. The proposed algorithm is based on digital computation of impedance, which uses symmetrical components of three-phase currents and voltages measured at the local end only. The proposed algorithm has been tested using MATLAB/SIMULINK (The MathWorks, Natick, Massachusetts, USA) software for a single line-to-ground fault considering wide variations in fault resistance, fault location, power factor, and short-circuit capacity of the source. [ABSTRACT FROM PUBLISHER]

• Active equipment is based on a cascaded H-bridge (CHB) inverter. • CHB inverter integrates neutral point overvoltage suppression and arc suppression. • Single line-to-ground fault can be identified during overvoltage suppression. • Asymmetric phase-to-ground parameters are considered in the arc suppression method. • Proposed method is verified in simulation and experiment testing. The resonant grounding system (RGS) has problems with neutral point overvoltage and single line-to-ground (SLG) fault. The existing active equipment can only suppress the neutral point overvoltage or the SLG fault arc, which has a single function and low utilization rate. In order to maintain the stable operation of the distribution networks and improve equipment utilization, the research on active equipment integrating the two functions is of great significance. Therefore, this paper proposes active equipment based on a cascaded H-bridge (CHB) inverter that integrates the functions of neutral point overvoltage suppression and arc suppression. The CHB inverter can switch from overvoltage suppression to arc suppression by the characteristics of zero-sequence voltage amplitude during overvoltage suppression. The arc suppression effect of the proposed arc suppression method is better than the existing flexible current arc suppression method in case of asymmetric phase-to-ground parameters. The simulation and experimental results verify the effectiveness of the proposed method under different influencing factors. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a new method for locating single line-to-ground (SLG) faults in ungrounded distribution systems. A distribution automation system is required to obtain all the required information from feeder remote terminal units via a communication channel with unpredictable time delays. Before locating a SLG fault, the faulted section is identified based on the absolute difference between the approximate zero-sequence angles of two adjacent nodes. Fault location starts by obtaining the synchronized zero-sequence voltage and current at the faulted node. This is achieved by forward calculation from the zero-sequence voltage and current at the substation. Because the zero-sequence current at the faulted node is calculated in synchronization with the substation, the other phasors at the faulted node are synchronized by phase compensation based on the phase difference between the synchronized and measured phasors corresponding to the zero-sequence current. Using the synchronized phasors, the fault location is identified through application of an orthogonal operator to the voltage equation at the faulted node. The performance of the proposed algorithm was evaluated using fault signals generated by the EMTP. The simulation results confirmed the validity and efficiency of the proposed algorithm for locating SLG faults in ungrounded distribution systems. [Copyright &y& Elsevier]

In general, a temporary overvoltage (TOV) on the healthy phases occurs because of the neutral-shift phenomenon during a single line-to-ground (SLG) fault. The TOV can destroy the insulation of electric devices and cause damage to other equipment and customer loads in just a few cycles. In practice, the TOV can be affected by numerous factors: the sequence reactance ratio of the interconnection transformer, the ratio of load to DG, and the distance to the fault. More importantly, inverter-based distributed generations (DGs) have different influences on the TOV from traditional synchronous-machine-based DGs. In this sense, this work performed an efficient and comprehensive investigation on the effect of these various parameter types and their extensive variations, based on steady-state analysis with sequence equivalent circuits and three-dimensional representations. The proposed methodology can facilitate judging the impact of multi-parameter conditions on the TOV readily and comparing the fault characteristics of synchronous-machine-based and inverter-based DGs. Finally, the results can be used for future studies on TOV mitigation techniques. [ABSTRACT FROM AUTHOR]

We developed an International Electrotechnical Commission (IEC) 61850-based centralized protection scheme to prevent single line-to-ground (SLG) faults in the feeders and busbars of ungrounded distribution systems. Each feeder intelligent electronic device (IED) measures its zero-sequence current and voltage signals and periodically transmits zero-sequence phasors to a central IED via a Generic Oriented Object Substation Event message. Using the zero-sequence phasors, the central IED detects SLG faults in feeders and busbars. To achieve centralized protection, angle differences between the zero-sequence currents and voltage phasors are exploited, and their calculation compensates for data desynchronization. The feeder IEDs were implemented using the MMS-EASE Lite library, while the transmitted zero-sequence phasors were calculated based on fault signals simulated by Power System Computer Aided Design / Electro-Magnetic Transient Design and Control (PSCAD/EMTDC). The central IED determined if the SLG fault was in a feeder or busbar by aggregating and analyzing the zero-sequence phasors received from the feeder IEDs. The results confirmed the validity and efficiency of our centralized protection scheme. [ABSTRACT FROM AUTHOR]

The power requirements of grids have risen as artificial intelligence and electric vehicle technologies have been used. Thus, the installation of distributed generators (DGs) has become an essential factor to streamline power grids. The objective of this study is to optimize the capacity and location of DGs. For this purpose, an objective function was defined, which takes into account the fault current and the levelized cost of energy, and a modified particle swarm optimization method was applied. Then, we analyzed a case of a single line-to-ground fault with a test feeder (i.e., the IEEE 30 bus system) with no DGs connected, as well as a case where the DGs are optimally connected. The effect of the optimally allocated DGs on the system was analyzed. We discuss an optimal layout method that takes the economic efficiency of the DG installation into account. [ABSTRACT FROM AUTHOR]