Resonant Grounding Distribution Research Articles

Fault section location in resonant grounding distribution systems based on feature subset optimization of phase current variation

SummaryThe existing single‐phase grounding (SPG) fault section location methods typically suffer from difficulty in feature selection, limited feeder terminal units (FTUs) configuration, and excessive dependence on communication, which weaken their generalization and robustness. To overcome these challenges, an SPG fault section location approach based on feature subset optimization is proposed. First, the relation between the position of FTU and its three‐phase current variation is analyzed, and its fault features are extracted to construct the candidate feature sets as feature subset optimization objects. Then, genetic algorithm and support vector machine (SVM) are combined to select the optimal feature subset with small dimensions and recognition error, which avoids the empirical errors of artificial feature selection. To reduce the cumulative errors, the SVM hyperparameters are simultaneously optimized. Finally, the SVM model is trained based on the optimal feature subset and hyperparameters. In the absence of zero‐sequence current measurement, three‐phase currents measured by FTU are locally processed to locate the fault section by the trained SVM. The experimental results verified the effectiveness and feasibility of the proposed method.

Active High-Impedance Fault Detection Method for Resonant Grounding Distribution Networks

Active High-Impedance Fault Detection Method for Resonant Grounding Distribution Networks

Cumulative Damage Effect of the Pin-type Porcelain Insulator Incipient Fault in the Resonant Grounded Distribution Networks

Cumulative Damage Effect of the Pin-type Porcelain Insulator Incipient Fault in the Resonant Grounded Distribution Networks

Faulty feeder selection based on improved Hough transform in resonant grounded distribution networks

Due to the weak fault characteristics and inaccurate fault line selection during high impedance faults, this paper proposes a new method for fault line selection in resonant grounded distribution networks based on improved Hough transform. Firstly, the variational modal decomposition (VMD) algorithm decomposes each feeder's zero sequence power under different operating conditions, then, using Sample entropy and Pearson correlation coefficient, selects the intrinsic mode function (IMF) with the highest correlation strength with the zero-sequence power of each feeder, called IMFK. Secondly, using the Hough transform to detect IMFK, obtaining the fitted straight line and IMFK angle during the fault's initial stage. The problem of identifying the zero-sequence power mode trend is transformed into a mathematical problem of determining the geometric shapes of straight lines and curves in the zero-sequence power mode image. Finally, a line selection criterion is established by integrating correlation coefficients to identify the faulty feeder in the distribution network system when a single-phase grounding fault occurs. The PSCAD simulation and on-site measurement results show that the proposed method can ensure the effectiveness and adaptability of the line selection.

An adaptive faulty phase detection method based on wavelet packet reconstruction energy of three-phase voltage signals in resonant grounded distribution systems

An adaptive faulty phase detection method based on wavelet packet reconstruction energy of three-phase voltage signals in resonant grounded distribution systems

High-Resistance Grounding Fault Detection and Line Selection in Resonant Grounding Distribution Network

The detection and selection of fault lines in resonant grounding distribution networks pose challenges due to the lack of sufficient state parameters and data. This paper proposes an approach to overcome these limitations by reconstructing the initial criterion for fault occurrence and fault line selection. Firstly, a combination of 15% of the traditional phase voltage and the sum of the zero-sequence voltage gradient is suggested as the initial criterion for fault occurrence. This improves the speed of the line selection device. Additionally, the transient process of high-resistance grounding in a resonant grounding system is analyzed based on the impedance characteristics of high- and low-frequency lines. The line selection criterion is then established by comparing the current and voltage derivative waveforms on high- and low-frequency lines. To verify the effectiveness of the proposed method, simulations are conducted. The results demonstrate that this method can effectively handle high-resistance grounding faults under complex conditions while meeting the required speed for line selection.

Advances on fault detection techniques for resonant grounded power distribution networks in bushfire prone areas: Identification of faulty feeders, faulty phases, faulty sections, and fault locations

Advances on fault detection techniques for resonant grounded power distribution networks in bushfire prone areas: Identification of faulty feeders, faulty phases, faulty sections, and fault locations

A modified charge similarity approach for detecting high impedance earth faults in resonant grounded power distribution networks

A modified charge similarity approach for detecting high impedance earth faults in resonant grounded power distribution networks

Faulty Feeder Detection Based on Grey Correlation Degree of Adaptive Frequency Band in Resonant Grounding Distribution System

Due to the particularity of their process, petrochemical enterprises have high requirements for the reliability of power supply. If a large-scale blackout occurs due to a grounding fault, it will pose a huge threat to safe production. When the resonant grounding system of petrochemical enterprises faults, due to the complex fault process and weak fault signal, it is difficult to accurately detect the faulty feeder by traditional methods. This paper presents a new method of grey correlation degree based on adaptive frequency band. Firstly, the transient zero-sequence current of each feeder is decomposed by coif5 wavelet, and the low frequency band a5 (power frequency component) and high frequency band d1, d2 (noise signal) are removed. By stacking all of the remaining frequency band signals to construct the wavelet area matrix, the faulty feeder detection characteristic scale and the first faulty feeder detection result are obtained. Secondly, based on the faulty feeder detection characteristic scale, the second faulty feeder detection result is obtained by the average grey correlation degree matrix, which detects the faulty feeder according to the waveform correlation degree. Finally, the final faulty feeder detection result is obtained by equal weight voting. In MATLAB/Simulink, the 10 kV resonant grounding system of petrochemical enterprises is modeled. A large number of simulation results show that the faulty feeder detection method is not affected by the initial phase angle (0°, 45° and 90°), transition resistance (10 Ω, 100 Ω and 1000 Ω), fault distance (1 km, 8 km and 15 km) and overcompensation degree (5%, 8% and 10%), and has good sensitivity.

Control of arc suppression devices for reducing powerline bushfires in resonant grounded power distribution networks using global terminal sliding mode controller

AbstractThis paper proposes a global terminal‐sliding mode controller (GT‐SMC) to compensate powerline bushfires due to electric faults in power distribution networks using arc suppression devices (ASDs). A GT‐sliding surface along with a new quick reaching law is used to design the controller. The major control objective is to compensate the fault current caused by single line‐to‐ground (SLG) faults to a value that cannot ignite fires in bushfire prone areas. A T‐type residual current compensator inverter within an ASD is controlled to achieve the goal. An integral‐sliding mode controller (I‐SMC) is also designed using a conventional reaching law for comparing the performance. Simulations studies and processor‐in‐loop implementations are carried out to investigate the ability of the GT‐SMC over an I‐SMC over a range of fault impedance scenarios. Dynamic properties of the voltage and current due to SLG faults along with the current injection by the ASD are analyzed against the standard criteria, to be followed to get rid of powerline bushfires. Results under different operating scenarios indicate that both controllers are capable to maintain standard criteria for preventing powerline bushfires though the GT‐SMC is proven to exhibit superior transient responses to that of the I‐SMC and integral backstepping controller.

Faulty Feeder Detection Under High Impedance Faults for Resonant Grounding Distribution Systems

The problem of high impedance fault (HIF) detection in resonant grounding distribution systems has not been well solved. In practical applications, the existing detection methods either have complex calculation processes and low accuracy or have a weak ability to adapt to complex fault conditions, which limits the adaptability of the existing methods. Based on a theoretical analysis, a novel faulty feeder detection method based on the inner product transformation of extreme values is proposed in this paper. First, to eliminate the interference of high-frequency components, the low-frequency characteristic modes of zero-sequence current of each feeder are extracted by the variational mode decomposition (VMD) algorithm. On this basis, the low-frequency intrinsic mode functions (IMFs) are processed by the first-order difference to obtain the current waveform after the difference. Second, the zero crossing point of the differential current waveform is obtained, and then the extreme value point of the original zero-sequence current is calibrated, including the maximum and minimum. Third, at the extreme value point, the comprehensive inner product values (CIPV) of each feeder are calculated. Then, when the values are positive, it is judged as a bus fault, when the value has at least one negative value, it is judged as a feeder fault, and the feeder with the minimum value is judged as a faulty feeder. A large number of simulations and field tests show that this method has better fault detection accuracy in practical applications and is suitable for strong noise interference and asynchronous sampling.

Ground Fault Detection Based on Fault Data Stitching and Image Generation of Resonant Grounding Distribution Systems

Fast and accurate fault detection is important for the long term, stable operation of the distribution network. For the resonant grounding system, the fault signal features extraction difficulties, and the existing detection method’s accuracy is not high. A ground fault detection method based on fault data stitching and image generation of resonant grounding distribution systems is proposed. Firstly, considering the correlation between the transient zero-sequence current (TZSC) of faulty and healthy feeders under the same operating conditions, a fault data stitching method is proposed, which splices the transient zero-sequence current signals of each feeder into system fault data, and then converts the system fault data into grayscale images by combining the signal-to-image conversion method. Then, an improved convolutional neural network (CNN) is used to train the grayscale images and then implement fault detection. The simulation results show that the proposed method has high accuracy and strong robustness compared with existing fault detection methods.

A hybrid sliding mode control scheme for rapid earth fault current limiters in compensated distribution networks in bushfire prone areas

AbstractA hybrid sliding mode controller is proposed for rapid earth fault current limiters (REFCLs) used in resonant grounded power distribution networks to self‐extinguish powerline bushfires where the concepts of the proportional integral (PI) action and nonsingular fast terminal sliding surface (NFTSS) are combined together to utilize the benefits of both schemes. A hybrid sliding surface is designed for obtaining the control input so that the fault current compensation is achieved by the residual current compensation (RCC) inverter used within a REFCL to a value that the fire does not ignite. The inclusion of an integral action along with the NFTSS helps to significantly reduce the chattering effect. Furthermore, a continuous function is introduced within the proposed scheme to replace the discontinuous signum function. The switches for the RCC inverter are controlled by deriving control actions from the Lyapunov stability theory applied on the hybrid PI‐NFTSS. The performance of the proposed controller is compared with a nonsingular fast terminal sliding mode controller. For this reason, this paper also includes the design process of nonsingular fast terminal sliding mode controller which is designed using only the NFTSS. Simulations under different scenarios having different fault resistances clearly depict the superiority of the proposed scheme over the nonsingular fast terminal sliding mode controller and an existing integral sliding mode controller in terms of maintaining transient responses.

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

Insulation Parameter Online Measurement Technology Based on Extended Zero-Sequence Circuits for Resonant Grounding Distribution Networks

To eliminate the measurement errors of insulation parameters caused by the internal impedance of VT (voltage transformer) and the damping resistance in resonant grounding distribution networks, a new online measurement technology based on an extended zero-sequence circuit is proposed. A constant current signal with variable frequency is injected into distribution network through a VT, and the return voltage is measured from another unloaded VT. An extended zero-sequence circuit is established to ensure that the injected current and the return voltage directly act on the insulation branch to ground; thus, the influence of the VT internal impedance can be eliminated. The resonance frequency is obtained according to the phase difference between the injected current and the return voltage, and the measurement error caused by damping resistance can be eliminated. Then, the capacitance to ground and leakage conductance can be accurately calculated. A measuring device based on the proposed technology was developed, and tests were carried out on a 10-kV distribution network laboratory and an actual 10-kV substation. The test results show that the proposed method has high measurement accuracy. The measurement process does not require a power interruption, and it does not affect the normal operation of the power system.

A Decentralized Fault Section Location Method Using Autoencoder and Feature Fusion in Resonant Grounding Distribution Systems

In industrial applications, the existing fault location methods of resonant grounding distribution systems suffer from low accuracy due to excessive dependence on communication, lack of field data, difficulty in artificial feature extraction and threshold setting, etc. To address these problems, this study proposes a decentralized fault section location method, which is implemented by the primary and secondary fusion intelligent switch (PSFIS) with two preloaded algorithms: autoencoder (AE) and backpropagation neural network. The relation between the transient zero-sequence current and the derivative of the transient zero-sequence voltage in each section is analyzed, and its features are extracted adaptively by using AE, without acquiring network parameters or setting thresholds. The current and voltage data are processed locally at PSFISs throughout the whole procedure, making it is insusceptible to communication failure or delay. The feasibility and effectiveness of the approach are investigated in PSCAD/EMTDC and real-time digital simulation system, which is then validated by field data. Compared with other methods, the experiment results indicate that the proposed method performs well in various scenarios with strong robustness to harsh on-site environment and roughness of data.

A comprehensive review of control techniques for compensating the fault current in resonant grounded distribution networks: From the perspective of mitigating powerline bushfires

Powerline faults are responsible for major bushfires around the world where arcs provoked from ground faults are common causes for igniting such fires. The grounding techniques (mainly resonant grounding) used in distribution substations and arc suppression devices play a crucial role for compensating fault currents in order to extinguish arcs so that the likelihoods of powerline bushfires are significantly reduced. Though passive arc suppression devices (e.g. Petersen coils) are extensively used for compensating the reactive component of the fault current, the active component of this current is still large enough to ignite the fire in bushfire prone areas for which active arc suppression devices are recently used. These active arc suppression devices incorporate residual current compensation inverters and the full compensation of the fault current rely on the control scheme of these inverters. This paper comprehensively reviews different control schemes that are used for compensating the fault current in resonant grounded power distribution systems. The existing control schemes are discussed in terms of the model used during the controller design process, loop structures, control block diagrams, and performance analysis frameworks (i.e. the type of fault impedances). It is worth mentioning that faults on resonant grounded power distribution networks exhibit the characteristics of high impedance faults and it important to consider this aspect for performance analysis of the control scheme. This paper also covers a brief overview of different grounding techniques used for mitigating fault currents and finally, the challenges with the existing controllers are identified in terms of extinguishing powerline bushfires. The comprehensive review motivates and guides future research activities on developing more efficient fault compensation techniques.

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.

A discrete sliding mode control scheme for arc suppression devices in resonant grounded power distribution systems to mitigate powerline bushfires

In this paper, a discrete sliding mode control scheme is developed for the residual current compensator (RCC) inverter in a arc suppression coil (ASC) which is used for eliminating the fault current in resonant grounded power distribution networks to eliminate the impacts of powerline bushfires. The proposed discrete sliding mode controller (D-SMC) is designed based on the dynamical model of the ASC where the model is first represented in the dq-frame and then discretized. The D-SMC ensures the injection of the desired current through the RCC inverter so that the current flowing through the neutral reduces to zero which in turn reduces the phase-to-ground voltage of the faulty phase and hence, mitigates the adverse effects of powerline bushfires. A discrete sliding surface is selected to determine the switching control inputs for the RCC inverter and the stability of the proposed D-SMC is also analyzed to ensure the injection of the desired current to the neutral point under any operating conditions while satisfying operational standards. The effectiveness of the proposed D-SMC is evaluated through simulation results in terms of minimizing the fault current through the injection of the current to the neutral point and comparisons are made with existing proportional integral (PI) controller through simulations as well as other control strategies.

A linear hybrid active disturbance rejection controller design to extenuate powerline bushfires in resonant grounded distribution power systems

This paper proposes a robust linear hybrid controller by combining the active disturbance rejection and proportional–integral controllers (ADRC+PI) for inverter-based arc suppression coils (ASCs) in resonant grounded distribution power systems (RGDPSs). Resonant grounding techniques are used in real power distribution networks for reducing the fault current in order to reduce the severity of powerline bushfires in the presence of single line-to-ground (SLG) faults. The severity of bushfire hazards due to these SLG faults depends on environmental conditions (e.g., wet or dry grounds) that define the behavior of the system. With respect to these conditions, the fault resistance will be lower for wet grounds for which the system model comprises one dominant pole while dry grounds force the system to have one dominant zero with two dominant poles. By considering the circumstances of such groundings, the behavior of power distribution systems changes when there are SLG faults. This paper investigates a detailed analysis in frequency- and time-domains to design a robust arc mitigator based on the hybrid ADRC+PI controller. Furthermore, the robustness of the proposed hybrid controller against the input disturbances is explored in terms of transient and steady-state stability analysis and the results are compared with the ADRC and PI controllers. In addition, the performance of the proposed hybrid ADRC+PI controller is justified by utilizing virtual- and real-time implementations in a digital signal processor (DSP) through MATLAB/SIMULINK platform on a 22 kV (line-to-line) RGDPS under distinctive grounding conditions.