Arc Suppression Coil Research Articles

ResNest-SVM-based method for identifying single-phase ground faults in active distribution networks

Single-phase grounding fault is the most common fault type in the distribution network. An accurate and effective single-phase grounding fault identification method is a prerequisite for maintaining the safe and stable operation of the power grid. Most neutral points of the active distribution network are grounded through arc suppression coils. In the active distribution network, the power supply in the network changes from one to multiple, which may change the direction of the fault current. In this paper, the superposition theorem is used to analyze the difference in the boosting effect of different types of distributed generators (DG) on line mode current in the sequence network diagram when DG is connected upstream or downstream of the fault point. Secondly, the composition of the zero-mode transient current of the fault line is analyzed. A judgment method based on the superposition diagram of transient zero-sequence voltage and current is proposed. Then, this paper improves the ResNest network and modifies the classifier of the last fully connected layer to SVM. Finally, the model in PSCAD is used to simulate single-phase grounding faults to obtain the training set and validation set. These datasets are used to train and test AlexNet, ResNet50, ResNeSt, and ResNeSt-SVM. The results show that under different fault points, transition resistances, DG access upstream and downstream of the fault point, and different fault initial phase angles, the ResNest-SVM model method can accurately identify the fault line and has better anti-noise ability than the other three network structures.

Ground fault protection algorithm of active distribution network based on energy extremum direction

AbstractAfter large‐scale distributed power sources are connected to the distribution network, the fault current undergoes noticeable changes, affecting the accuracy of traditional single‐phase grounding fault algorithms. Therefore, the objective of this paper is to address the impact of distributed power integration on the grounding algorithms of distribution networks. The main contribution is: by establishing an electrical system structure and model for distribution network grounding faults that include distributed generation (DG), theoretically deriving and calculating the transient zero‐sequence current frequency changes at the moment of fault, analysing the directional characteristics of zero‐sequence currents under DG connection conditions, designing a local grounding fault judgment algorithm based on energy extremum direction, and providing a fault judgment and isolation process for grounding fault monitoring devices. The results show: through simulation and experimentation, the algorithm was tested, and the method can reliably judge grounding faults under various transition resistances, different numbers and capacities of connected distributed power sources, and different grounding switch‐on angles. The applicability of the algorithm covers both methods of neutral grounding through an arc suppression coil and ungrounded neutrals, adapting to scenarios with or without DG connections.

Double closed loop PI control with full compensation arc elimination based on zero sequence voltage of neutral point

Aiming at the problem of zero sequence voltage generated by unbalance parameters of line to ground, which affects arc suppression effect of grounding fault of controllable voltage source. By analyzing the influence of ground unbalance parameters on the arc suppression effect of controllable voltage source under different grounding modes, the mechanism of full compensation arc suppression based on zero sequence voltage of neutral point is revealed, and on this basis, a fully compensated arc suppression model of controllable voltage source controlled by double closed loop PI is established, and the deviation control is carried out by using the neutral voltage of distribution network and the voltage of fault phase supply. The residual voltage ring adopts the ground fault phase residual voltage for closed loop control. The simulation results show that the dual-closed-loop PI control algorithm can continuously stabilize the output waveform of the controllable voltage source. When the transition resistance is 0.1 ~ 10 kΩ, the residual voltage stabilization time of the independent controllable voltage source grounding method is 43 ms ~ 2.4 s, and the parallel arc suppression coil grounding method is 43 ms ~ 4.7 s. The proposed dual closed-loop PI control method for neutral point voltage deviation and fault residual voltage can stabilize the residual voltage of the grounded fault phase to below 10 V, forcing reliable arc extinction at the grounded fault point, exhibiting good stability. Low-voltage simulation tests have also proved the feasibility of the algorithm.

An advanced integral sliding mode controller design for residual current compensation inverters in compensated power networks to mitigate powerline bushfire hazards

AbstractThis work deals with designing an advanced integral sliding mode controller (AISMC) for residual current compensation (RCC) inverters connected with arc suppression coils to compensate for power distribution networks where the main idea is to alleviate hazardous circumstances caused by electric faults on powerlines. The key advancement in the proposed AISMC over traditional sliding mode controllers is the utilization of an improved exponential reaching law which ensures the faster convergence of the desired control objective that is the fault current compensation in this particular application. An improved exponential reaching law (IERL) used in this work is a combination of the exponential and constant‐proportional reaching laws (while existing approaches use constant reaching laws) which assists to minimize the current injection error through the RCC inverter in the steady‐state. The integral action in conjunction with the exponential function in the sliding surface, based on which the proposed controller is designed, helps to eliminate the chattering effects in a quickest way that can be evidenced from the settling time and percentage overshoot. The feasibility of the proposed AISMC is theoretically assessed by analyzing the stability using the Lyapunov stability theory. Simulation and processor‐in‐loop results further justify the theoretical foundation by confirming the desired current injection and compensating voltage and current due to the fault. Finally, results are compared with a TIMSC for demonstrating the superiority of the AISMC.

Faulty line detection for cross‐line same‐phase successive ground faults in distribution network based on transient characteristics

AbstractCurrently, theoretical analysis of single‐phase grounding (SPG) faults in low‐current grounding systems has reached a high level of refinement, and the corresponding detection methods have matured. However, there is a significant lack of research on successive grounding (SG) faults, particularly in the area of detecting cross‐line same‐phase successive grounding (CSSG) faults in arc suppression coil grounding systems. To address these issues, a novel faulty line detection method based on transient characteristics of CSSG is proposed. Firstly, a transient equivalent circuit is established, and the characteristics of transient zero‐sequence current (ZSC) are theoretically analysed. Secondly, variational mode decomposition (VMD) is employed to extract low and high‐frequency information from intrinsic mode functions (IMFs). Subsequently, a fault initiation criterion based on kurtosis theory and the Teager‐Kaiser energy operator (TKEO) is proposed, which can accurately detect the occurrence time of secondary faults. Finally, a method for faulty line detection based on cross‐correlation distance (CCD) and transient energy (TE) is proposed. The results of PSCAD simulation under different conditions and field test affirm the accuracy of the analysis and the effectiveness of the proposed method.

A Novel Method for Line Selection for Cross-Line Two-Point Successive Grounding Faults Utilizing Transient and Steady-State Information

In order to improve the performance of an arc suppression coil grounding system in handling cross-line two-point successive grounding faults (CTSGs), the applicability of the transient quantity method and the steady-state quantity method for assessing CTSGs is analyzed. Then, a novel method for line selection for CTSGs was proposed, which comprehensively utilizes transient and steady-state information. Specifically, this method adopts a continuous line selection process, with priority given to the transient quantity method, and a supplementary line selection process, with priority given to the steady-state quantity method. After accurately selecting some faulty lines, such lines are tripped, and then, the process proceeds with continuous line selection again. When the number of cycles exceeds the set value, and the fault line cannot be completely cut off, they are tripped one by one according to the degree to which they are approaching the steady-state method criterion, from large to small. Furthermore, in response to the dramatic increase in computing volume that is caused by the continuous application of the transient method in on-site applications and the impact of current transformer accuracy on the steady-state method, this paper proposes corresponding solutions. PSCAD simulation, full-scale tests, and field recording data tests verify that this paper’s method can accurately detect a CTSG.

A Nonlinear Discrete-Time Backstepping Model Predictive Controller Design for Active Arc Suppression Coils in Compensated Power Systems to Mitigate Powerline Bushfire Hazards

A Nonlinear Discrete-Time Backstepping Model Predictive Controller Design for Active Arc Suppression Coils in Compensated Power Systems to Mitigate Powerline Bushfire Hazards

The Analysis of Capacitance Current Testing Method

The accuracy of capacitance current measurement is directly related to the choice of arc suppression coil. In this paper, the capacitance current test of 10 kV and 66 kV substations in Shenyang and Dalian is carried out by using a capacitance current tester produced by different manufacturers. The measurement mainly uses the 10 kV PT open triangle signal injection method (for 3PT), 10 kV 4PT secondary signal injection method (for 4PT), and 66/10 kV transformer neutral signal injection method. The test data are compared with the test data of laboratory standard equipment. Through comparative analysis, it can be seen that some manufacturers failed to measure capacitive current or the deviation of test results is large, and the test results of each test method of other manufacturers are closer to the measured values in the laboratory.

A Novel Fault Current Full Compensation Method in Active Flexible Grounding Distribution Networks

As the power equipment represented by the inverter is gradually increasing in the power systems, the residual capacitive component of the grounding fault current cannot be ignored. To solve the problem of insufficient compensation for capacitive components in the traditional arc suppression coil grounding mode, a grounding fault current full compensation method based on the active flexible grounding mode was proposed. First, the principle of full compensation in the active flexible grounding mode was analyzed to provide a reference for the injected current of voltage arc suppression full compensation. Then, the inverter control system was designed, and a closed-loop control method was proposed, both of which can ensure the stable target current of the system. Finally, the simulation results compare the fault current compensation difference between the two grounding modes, and the practicability of the proposed compensation method was verified.

Flexible composite suppression method for ground arc in resonant grounding system

AbstractA current‐voltage composite controller for an arc suppression inverter is designed. The current and voltage at the fault point are reduced by injecting current and regulating the neutral point voltage to completely eliminate the risk of fire and overvoltage caused by a single‐line‐to‐ground fault arc. A cascaded inverter is used, and the effects of the ground parameter measurement, line impedance voltage drop, harmonic current and arc suppression coil on the current control, voltage control and composite control methods are analysed and compared. Finally, software simulations and industrial prototype experiments show that the proposed composite control method is effective and less affected by ground parameter measurement and line impedance voltage drop and has better adaptability.

Research on the mechanism and restraining measures of ferroresonance in distribution network based on ATP-EMTP

In order to monitor the three-phase voltage of the busbar to ground, the substation bus is usually connected to the electromagnetic voltage transformer by YN connection in the distribution network. Under certain conditions, the excitation characteristics are easy to saturate, and the inductance parameters match the system capacitance, excite ferromagnetic resonance, cause damage to fuses or voltage transformers, and seriously affect the safe and stable operation of the power system.By analyzing typical single-phase ground faults, this paper introduces the generation mechanism of ferromagnetic resonance and the main suppression measures at this stage. The electromagnetic transient analysis software ATP-EMTP is used to analyze the operation of a typical transformer, and the change of ferromagnetic resonance waveform after the neutral point of the voltage transformer is replaced by resonant eliminator and arc suppression coil grounding. The results show that when eliminating the single-phase ground fault, it is easy to cause the frequency division resonance of the system, and the use of these two measures can effectively suppress the ferromagnetic resonance of the system.

Study on fault waveform library of PT high voltage side fuse in hydropower station

In the arc-suppression coil grounding system of a medium voltage distribution network, high voltage side voltage transformer insurance fusing faults frequently occur, including fusing during startup and grid connection, fusing during operation, fusing during the shutdown, etc., which will directly affect the accuracy of measurement, metering, protection, and other secondary equipment. In this paper, we used the calculation of electromagnetic transient EMTP-ATP software, theoretical analysis of the typical hydropower station wiring and parameters of the medium voltage system, set up the improved model of neutral point grounding system, simulation of single-phase earth fault line and disappeared in the transient process, calculation of PT transient current, to verify that the way to study the mechanism of frequent fusing of fuse in the PT. Typical fault waveform databases are established under different bad working conditions (ferromagnetic resonance, low-frequency nonlinear oscillation, lightning wave invasion, etc.).

IMPLEMENTATION OF 20 kV VOLTAGE NETWORK IN UKRAINE

Background Due to the war, the medium voltage networks are in an extremely difficult condition, they have a high degree of depreciation of electrical equipment and a low level of automation. The energy system of Ukraine has a problem of modernizing medium voltage networks and transfer them to a new class of rated voltage of 20 kV.
 Objective Overall overview of 20 kV networks and organization of their topology with renewable energy sources and " energy storages ". 
 Methods A network model in the MatLab software package was used to study "energy accumulators". The study of the efficiency of the "energy storages" was carried out in the variability of the power to the total load, as well as the time of connection to the network.
 Results The need to transfer voltages of 6 (10) kV to a higher level of 20 kV has been proven. Various methods of grounding the neutral of medium voltage networks are considered and the most effective modes of neutral grounding for 20 kV networks are determined: through an arc suppression coil or through a resistor. A comparative analysis of networks with and without energy storage was carried out. In 20 kV networks, without the use of energy storage, energy consumption from the network and power losses will increase. When using storage devices, they are permanently connected to the network and have their own power losses. Batteries connected to a 20 kV network lead to an oscillating process that has a damping character (within 2 seconds).
 Conclusions The transition from the voltage level of 6 (10) kV to 20 kV will significantly increase the efficiency of distribution networks and reduce electricity losses. The installation of energy storage in 20 kV distribution networks will allow the introduction of new intelligent systems to ensure the interests of safety, economy and energy efficiency and will create the prerequisites for the implementation of the Smart Grid concept.

Analysis of Typical Faults and Defects and Testing Methods of Complete Set of Turns-Regulating Arc Suppression Coil

In recent years, many automatic tracking compensation turns-regulating arc suppression coils have been installed in substations to compensate for the increasing capacitive current. However, the frequent occurrence of the fault defects of the arc suppression coil itself has caused a series of new problems, such as causing abnormal bus voltage at the low-voltage side of the substation. Through the analysis and classification of typical faults and defect cases of the complete set of turns-regulating arc suppression coil, it is found that the most vulnerable parts of the device are the on-load tap changer, damping resistance cabinet and control unit. Aiming at the problem that the detection means of the complete arc suppression coil device are insufficient, this paper proposes a new test method, including a compensation characteristic test and relevant accessories test. Based on the new test method, a simulation test platform was built to test 2 sets of turns-regulating arc suppression coil devices. The results show that the new test method has great application value.

A Novel Topology for Grounding Fault Voltage Compensation Based on Voltage Clamping

In view of the limited arc suppression capability of the traditional arc suppression coils, a novel grounding fault voltage compensation topology for single-phase grounding faults based on voltage clamping is proposed in this article. The novel topology uses a single-phase isolating transformer (SPIT) to clamp the fault voltage to below the personal safety voltage. The primary side of SPIT is connected to the faulty phase and its leading phase; the secondary side of SPIT is connected to the fault leading phase and ground. The influence of the leakage impedance of SPIT is analyzed. Parameters of leakage impedance angle and ratio of the SPIT are designed to achieve a desirable compensation effect. The proposed topology does not rely on the neutral point of the distribution network. The compensation effect of the proposed topology under different grounding capacitances and grounding resistances is analyzed. Simulation and experimental results show that the proposed passive compensation topology has the advantages of low costs, well compensation effect, and strong robustness, which can effectively extinguish arcing.

Research on parallel operation of active intervention type arc extinguishing device and arc suppression coil

The arc extinguishing mode of neutral grounding via arc suppression coil (ASC) is widely used in the distribution network. With the increasing application of active intervention type arc extinguishing device (AIT-AED), there is a situation that the AIT-AED and the ASC operate in parallel, but the parallel operation technology of these two devices is not mature. Hence, An experimental study was carried out to analyze the effect of parallel operation on the function of AIT-AED in this paper. The results show that the parallel operation of AIT-AED and ASC improves the high resistance grounding identification ability of AIT-AED, but the judgment of fault phase and fault type is disturbed. The relevant conclusion can provide reference for developing the parallel operation strategy of AIT-AED and ASC.

Modeling Dependence of Active Power Loss in Plunger Core Arc Suppression Coils on Applied Voltage and Compensation Winding Current

Modeling Dependence of Active Power Loss in Plunger Core Arc Suppression Coils on Applied Voltage and Compensation Winding Current

Fault transient feature extraction method of 66kV transmission line based on improved wavelet threshold and CEEMDAN-FME

In the 66kV transmission line, the compensation effect of the arc suppression coil, so the amplitude of fault zero sequence current is weak after the occurrence of single-phase grounding responsibility. The fault characteristics are not obvious, and there is environmental noise interference during fault signal acquisition, which further increases the difficulty of ground fault feature extraction. To solve the above problems, a fault transient feature extraction method of 66kV transmission line is proposed, based on improved wavelet threshold and Complete Ensemble Empirical Mode Decomposition with adaptive noise (CEEMDAN) - Fuzzy measure entropy (FME). The characteristics of single-phase grounding transient fault in small current grounding system are analyzed. The transient fault signal was preprocessed by an improved wavelet threshold method, and the transient fault characteristics were extracted accurately by CEEMDAN-FME processing. The proposed method has good anti-noise performance through the simulation comparison and verification of denoising processing and transient feature extraction by MATLAB. It can effectively extract fault features when the interference degree is significant.

Fault Phase Selection Method Based on Single-Phase Flexible Arc Suppression Device for Asymmetric Distribution Networks

The phase-to-ground admittance in distribution networks is asymmetric. This asymmetry is aggravated by the arc suppression coil, resulting in zero-sequence overvoltage. The magnitude of zero-sequence overvoltage can exceed the line-to-ground voltage, endangering the operation of electrical equipment. Moreover, after the occurrence of a single-line-to-ground fault, the change law of the three-phase voltage is affected by the zero-sequence overvoltage, leading to misjudgment of the fault phase. Accordingly, this paper proposes a fault phase selection method based on active current injection that can adapt to asymmetric distribution networks. The fault phase is selected by injecting current and calculating the equivalent power supply voltage of the faulty line without increasing the ground-fault current. The high sensitivity of the proposed fault phase selection method was verified for high impedance faults through software simulations and prototype experiments. Moreover, the zero-sequence overvoltage can be suppressed by a single-phase flexible arc suppression device during the normal operation of distribution networks. The ground-fault current can be quickly suppressed at different ground-fault locations and resistance values, ensuring the extinguishment of the ground-fault arc.

A Method for Measuring Capacitive Current in Arc Suppression Coil Grounding System

With the rapid development of the national economy, the system cabling rate continues to improve, the system capacitive current continues to increase, and the arc suppression coil grounding method is more and more widely used. Among them, the pre adjustable turn adjustable arc suppression coil accounts for the highest proportion. How to accurately, quickly and real-time measure and calculate the capacitive current of the system is the foundation to realize the automatic tracking and compensation of the arc suppression coil, It is also the key to reliably extinguish the arc and reduce the influence range of the fault when the single-phase grounding fault occurs in the system. Based on the analysis of the variation law of the capacitive current in the distribution network neutral grounding system through the arc suppression coil, this paper proposes a new method for measuring the capacitive current based on the resonance point curve fitting, which is suitable for the pre adjustable turn adjustable arc suppression coil grounding system, and verifies its reliability and accuracy through simulation.