Arc Suppression Coil Grounding Research Articles

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.

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 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.

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.).

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.

GAN-based semi-supervised learning method for identification of the faulty feeder in resonant grounding distribution networks

Accurate identification of the faulty feeder after a single-phase-to-ground fault in an arc suppression coil grounding distribution network remains a significant challenge. Recently, intelligent learning-based methods and especially deep learning methods have attracted much attention. To our knowledge, these methods usually assume that the training samples are sufficient. However, it is difficult to obtain abundant labeled samples in a practical environment. In this paper, we propose a semi-supervised learning model based on generative adversarial networks (GAN) to reliably identify the faulty feeder. The discriminator of GAN classifies the synthetic data which is generated by the generator into a new class. We revise the loss functions of the discriminator and generator, and the discriminator and generator play a maximum and minimum game. The proposed method can significantly improve the performance of faulty feeder identification when a small percentage of training samples are labeled. Various types of faults are simulated to consist of the training dataset and testing dataset. The simulation test results, sensitive analysis, comparing analysis, and recorded data obtained in a full-scale test field test demonstrate the higher performance of the proposed method.

AC Fault Ride-Through Strategy of a Transformerless Soft Normally Open Point

This paper focuses on the soft normally open point (SNOP) which has no transformers and connects to the 10 kV distribution network through the arc suppression coil grounding mode. A mathematical model containing positive-, negative-, and zero-sequence components under AC fault is established by the circuit analysis and the sequence component decomposition. Then the voltage fluctuation mechanism at the DC side and the non-fault AC side caused by the zero-sequence voltage on the fault side is analyzed under the case without transformers. Taking the single-phase grounding fault as an example, the fluctuation formula of the DC voltage and AC voltage is deduced in detail. Based on the theoretical analysis, the zero-sequence control strategy and the sub-module improvement strategy of the modular multilevel converter (MMC) are proposed. A back-to-back SNOP simulation model is established in PSCAD/EMTDC. The simulation results verify the accuracy of the theoretical analysis, as well as the validity of zero-sequence control and MMC topology improvement strategies.

Identification of Single Phase to Ground Faults in Power Distribution Systems with RG Technique

Fault in a power system is an irregular condition that interrupts the stability of the system and causes a high fault current to flow through the power systems and its devices. Single phase to ground fault is an unsymmetrical fault that takes place between any phase of the system and ground. It is the most frequently occurring fault (70%-80%) that happens in the power system. Resonant Grounding (RG) is the proposed approach that reduces a fault current of a single phase to ground fault to a minimum level that is often independent of fault impedance. In this case, the single phase to ground fault current is too small and the typical overcurrent relay does not respond in this circumstance. As a result, a new and improved approach for detecting single phase to ground fault failures in arc suppression coil grounding distribution system with very low fault currents, though the fault impedance is low, is required. The faults are initially detected based on the neutral voltage displacement by a regionalized fault detection technique. The statement is validated by simulating a single phase to ground fault on an IEEE thirteen node test system and the results are presented. Since it employs local voltage and current information to detect power system fault condition, the suggested technique does not require communication between circuit breaker, relays, transformer, transmission lines etc. This approach can be used to a variety of different forms of unsymmetrical faults.

Simulation Research on Automatic Compensation Technology of ADN Based on Neutral Point Active Compensation

When the single-phase grounding fault occurs in the distribution network, the neutral point via the arc suppression coil grounding mode can effectively reduce the fault current and realize the self-extinguishing arc. However, as a large number of distributed generator and power electronic devices are connected to the distribution network, the structure of the network becomes more and more complex. In order to effectively reduce the fault current, the 10 kV active distribution network (ADN) was taken as the research object for simulation in this paper, and the support vector machines (SVM) algorithm were used for training by extracting the fault components, the neutral compensated current components and so on as eigenvalues. Used the controller to judge the system compensation state and complete the automatic compensation. The results show that under ideal conditions, the judgment time of the algorithm is 0.32 ms. And the algorithm can quickly respond to the fault component, improve the response speed and reduce the damage to electrical equipments.

Research on fault section location method of distribution networks with arc suppression coil grounding based on energy leakage function

In distribution networks with arc suppression coil grounding, the fault line can be set as the energy leakage channel of the capacitive current of the entire system. During the period from fault occurrence to the whole action process of arc suppression coil, there is abundant fault information in the transient waves. However, the data of this period are usually ignored in previous methods. In this study, a novel fault section location method based on the leakage energy function is proposed. Only the fault phase voltage and fault phase current are used in the proposed method, to avoid the difficulty of the zero-sequence current measurement. Then, the action characteristics of two types of arc suppression devices are analysed. The influence of the capacitor current on the fault phase voltage and current during the entire process of arc suppression coil operation is deduced. The difference between the leakage energy on both sides of the fault section is used as the criterion for fault section location. Finally, the effectiveness of the method is verified by a case study. The simulation results indicate that the proposed method has high sensitivity and high impedance adaptability, that will have more advantages in the actual situations.

Single-phase-to-ground fault model analysis of arc suppression coil grounding system in distribution network

Start your abstract here…The short-circuit fault type of China’s medium-voltage distribution network is 80% single-phase ground fault. Since the non-effective grounding system can continue to operate for 1∼2 hours after single-phase-to-ground fault, the analysis of the single-phase-to-ground fault model is very necessary for the arc-suppression coil grounding mode in distribution network. In this paper, by establishing a single-phase ground fault model of the distribution network with arc-suppression coil grounding method, it is theoretically analysed that is the different transition resistances in metallic grounding, high-resistance grounding and intermediate state, and use ATP/EMTP simulation to analyse the fault occurrence, the change and difference of the current waveform on the fault line and the normal line as well as the arc suppression coil. It is concluded that when the single-phase ground fault occurs in the distribution network under the grounding mode of the arc suppression coil, no matter how the transition resistance changes, the current direction of the fault line and the normal line (when the predetermined reference direction is the bus flowing to lines) is reversed, but the difference between the fault current and the normal current is weakened with the change of the transition resistance, so different faults models should be used for different grounding resistances to analyse the transient currents of normal and fault lines on the zero sequence circuit model.

Research on Line Selection Method of Single-phase Earth Fault Based on Improved Dynamic Time Bending Distance Similarity Word

The problem of fault line selection for the distribution network of neutral point via arc suppression coil grounding has not been solved for a long time. Based on this, a single-phase ground fault line selection method based on dynamic time bending distance similarity is proposed. Firstly, the single-phase ground fault feature analysis of the distribution network of the zero-mode network is used to determine the electrical characteristic quantity of the single-phase ground fault line selection. Then, the faulty electrical feature quantity is improved by the dynamic time bending distance algorithm to form the distance matrix. The similarity data processing is performed on the matrix to obtain a line selection vector, and then the fault line is selected. Finally, the single-phase ground fault system model of 10kV distribution network is constructed by Matlab/Simulink. The correctness and feasibility of single-phase ground fault line selection method based on the dynamic time bending distance similarity is verified by simulation under different fault conditions.

Single‐phase grouding fault analysis and control scheme of transformerless flexible multistate switch

The compact design is suitable for the urban areas with intensive loads. The flexible multistate switch (FMS) can effectively reduce the footprint by removing transformers, which is the development trend of the flexible AC distribution equipment. In PSCAD/EMTDC, a simulation model containing two supply areas embedded in a transformerless FMS is built. Through the single-phase grounding fault simulation under the arc suppression coil grounding, the characteristics of zero-sequence component of FMS are analysed. By means of circuit analysis and sequence component decomposition, the intrinsic mechanism of AC/DC voltage fluctuation in the non-fault supply area caused by the zero-sequence component at the fault area is analysed, and the simulation result is explained. Based on the feeder transformation, a new protection and control scheme is proposed to overcome the problem of the zero-sequence ride through among different supply areas.

Investigation of Earth Fault Characteristics Under Different Neutral Grounding Methods

Medium voltage (MV) distribution systems use different methods for grounding the neutral point. Influences of these grounding methods on the single line to ground (SLG) fault characteristics are discussed in this paper. Jordanian MV network is used as a case study. The network has both underground cables and overhead lines. Simulation models are implemented in both MATLAB®/SIMULINK® and DigSilent/Power Factory®softwares. The models allow detailed investigation of the different fault factors and grounding methods. Results are obtained to evaluate the impact of each grounding method on the SLG fault features. Isolated neutral, solid grounding, resistance grounding and Petersen coil (Arc suppression coil) grounding are compared for different fault locations, fault incidence angles, and fault resistances. Current and voltage waveforms, as well as symmetrical components are used to describe the fault case.

Application of DC component to select fault branch in arc suppression coil grounding system

When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.

A Fault Line Detection Method Based on Wavelet Packet Analysis in Distribution Network

With the rapid development of power network automation, the detection of the default single-phase grounding fault line in small current neutral grounding system has became a hot spot in research of power network system. Generally, power network neutral point is not grounded or grounded through arc-suppression coil grounding. When single phase grounding fault occurs, the power network system is named as small current grounding system since the grounding short-circuit is small due to a low-impedance short circuit.

MATLAB Power System Simulation of Resonant Grounding Fault

In order to handle the situation of power system grounding fault better, this paper built the mathematical model of power system resonance grounding fault based on the resonance grounding principle. And simulated the resonance processes by using MATLAB/SIMULINK/ SIMPOWERSYSTEM (SPS) software. The obtained results show that there will appear zero sequence current at each point of power system when the grounding faults occurrs. And if the circuit has the point of biggest amplitude of zero sequence current, then it is just the fault phases. The simulation data further verified that arc suppression coil grounding could directly decreases the grounding current when the single-phase grounding fault occurred. Moreover, it effectively eliminates the arc from the process and becomes the more reasonable grounding mode.