Resonant Grounding Research Articles

Fault Location Method in Resonant Grounded Networks Based on Distributed Modulation and Compensation Adjustment

This paper proposes a novel ground-fault location method in resonant grounded systems based on distributed modulation and compensation adjustment. After the permanent single-phase ground fault arc has been suppressed, the Petersen coil will be adjusted to make the zero-sequence currents at the upstream monitoring points of the fault point exceed a certain threshold and be modulated in situ . At this time, the corresponding modulated signals can be extracted from the neutral-to-earth voltage on the busbar for measuring these zero-sequence currents. Taking the carrier-frequency of every monitoring point as its identification tags and the variation characteristic of the zero-sequence currents along feeders as another detection criterion, the fault point can be determined online accurately without a high-performance real-time monitoring network. In this paper, the carrier-frequencies allocation and signal conditioning scheme are proposed for a good detection accuracy of the zero-sequence currents, then the signal detection principle with the control of Petersen coil is described in detail. Simulations and experiments verified the feasibility of the proposed fault location method.

Electrical Safety Analysis in the Presence of Resonant Grounding Neutral

The resonant grounding is one of the possible methods of the system neutral grounding for the medium voltage distribution. IEEE standards do define this grounding configuration, but important advantages and drawbacks of the resonant grounding might not be fully known, due to its rather uncommon application in North America. On the other hand, resonant grounding in Europe is imposed by the increased requirements for power quality, especially for medium-voltage (MV) industrial users, imposed to electric utilities by regulatory authorities, with the purpose to protect the interests of users and consumers. Level of the continuity of the service, magnitude and phase of ground-fault currents, magnitude of touch voltages, all depend on how the neutral is connected to ground. In this paper, the authors will discuss electrical safety features of the resonant ground, and analyze issues when a substation, originally operated with different methods of system neutral grounding, is reconfigured with a resonant ground. In particular, a conservative approach for preserving safety during high-voltage (HV)-MV substations’ reconfiguration is herein proposed; the cases of the substation reconfiguration from resonant grounding to isolated-from-ground and vice versa shall be analyzed. Finally, the analysis of the impact of the use of Petersen coil on the global grounding systems will be provided.

Single Line-to-Ground Faulted Line Detection of Distribution Systems With Resonant Grounding Based on Feature Fusion Framework

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.

Decoupling Capacitor Placement on Resonant Parallel-Plates Via Driving Point Impedance

A semi-analytical method is proposed to evaluate the effectiveness of a decoupling capacitor on resonant power and ground planes. New expressions are developed relating the pin impedance to relative placement of a capacitor with associated angular and distance parameters. To speed up the solution of resulting transcendental equations, a 2-D iterative technique is proposed, which yields the effective distance as well as the angle between a decoupling capacitor and a power pin. The partial derivatives of the corresponding Jacobian matrix are analytically derived. Numerical examples are presented to demonstrate the validity of the proposed method, which also investigates the effect of plane edges on pin impedance.

Analysis and design of a compact CRLH inspired – Defected ground resonators for triple band antenna applications

In this work, a triple-band negative refraction index metamaterial antenna employing a new configuration of the complementary split ring resonator is presented. The antenna has been designed to operate at 2.4 GHz, 2.9 GHz, and 4.38 GHz. The complementary split ring resonator is etched in the ground plane of a microstrip patch with a new shape of defected ground structure for reducing the particle size. The configuration has the advantages of smaller size compared to conventional complementary split ring resonators presented in the literature. The proposed antenna has a patch size of 28 × 28 mm2. Compared to conventional single band microstrip patch radiator size; its size has been reduced by 30% at the lowest operating frequency. The antenna has reflection coefficient less than −10 dB at the three operating frequencies. The antenna has a reasonable gain at the three operating frequencies of 3.28 dB, −4.5 dB and −3.1 dB at 2.4 GHz, 2.9 GHz, and 4.38 GHz, respectively. Also, the antenna efficiency is 57.6%, 6.3%, and 12.3% at these frequencies, respectively.

A Fault Section Location Method Based on Matrix Beam Algorithm

A fault segment localization method of resonant grounding system based on matrix beam algorithm is proposed. Analyzing the difference of the positive-sequence real-time current in the fault-added state between the upstream and downstream of the fault point when a single-phase ground fault occurs in a small-current grounding system. The criterion of the fault section is that the positive-sequence real-time current mainly flows through the upstream of the fault point. On this basis, the matrix beam algorithm is used to extract the instantaneous positive-sequence real-time power frequency amplitude of each detection point on the fault line of the resonant grounding system, and the area between two adjacent detection points with the largest amplitude difference on the fault path is the fault section.In addition, the effectiveness of the method is verified by the built matlab model.

High-Performance Low-Pass Filter Using Stepped Impedance Resonator and Defected Ground Structure

A microstrip low-pass filter (LPF) using reformative stepped impedance resonator (SIR) and defected ground structure (DGS) is proposed in this paper. The proposed filter not only possesses the advantage of high frequency selectivity of SIR hairpin LPF with internal coupling, but also possesses the large stop-band (SB) bandwidth by adjusting the number and area of DGS units. The LPF proposed in this paper possesses the properties of miniaturization, wide SB, high selectivity, and low pass-band ripple (PBR) simultaneously. The characteristic parameters of the proposed LPF is that: the pass-band (PB) is 0~2 GHz, the PBR is 0.5 dB, the SB range is from 2.4 GHz to 9 GHz when the attenuation is under 20 dB, and the maximal attenuation could reach 45 dB in the SB. The size of this proposed LPF is 0.13 λ × 0.09 λ ; λ is the corresponding wavelength of the upper PB edge frequency of 2 GHz.

Fault Line Selection Method for Resonant Grounding System Based on Improved PSO-SVM

The fault line selection of traditional resonant system method has low reliability and poor accuracy. Although the ordinary intelligent line selection method improves the line selection accuracy, the system has a long running time and is not effective. In this paper, an improved intelligent line selection method based on particle swarm optimization (PSO-SVM) is proposed. The traditional particle swarm optimization algorithm is improved, which makes the SVM model parameters faster and less likely to fall into local optimum. Combining the fifth harmonic method and the wavelet packet variation method to achieve efficient selection of grounding faults in resonant systems. The simulation results show that the proposed method has high accuracy and is not affected by factors such as grounding resistance and fault distance.

Identifying Faulty Feeder for Single-Phase High Impedance Fault in Resonant Grounding Distribution System

The identification of faulty feeder for single-phase high impedance faults (HIFs), especially in resonant grounding distribution system (RGDS), has always been a challenge, and existing faulty feeder identification techniques for HIFs suffer from some drawbacks. For this problem, the fault transient characteristic of single-phase HIF is analyzed and a faulty feeder identification method for HIF is proposed. The analysis shows that the transient zero-sequence current of each feeder is seen as a linear relationship between bus transient zero-sequence voltage and bus transient zero-sequence voltage derivative, and the coefficients are the reciprocal of transition resistance and feeder own capacitance, respectively, in both the over-damping state and the under-damping state. In order to estimate transition resistance and capacitance of each feeder, a least squares algorithm is utilized. The estimated transition resistance of a healthy feeder is infinite theoretically, and is a huge value practically. However, the estimated transition resistance of faulty feeder is approximately equal to actual fault resistance value, and it is far less than the set threshold. According to the above significant difference, the faulty feeder can be identified. The efficiency of the proposed method for the single-phase HIF in RGDS is verified by simulation results and experimental results that are based on RTDS.

A compact high-selective dual-band pass filter

A compact high-selective dual-band pass filter is designed. The first passband is created by complementary open resonant ring defect ground structure, and the second is created by open circuit branch resonator. The presented design has advantages of steeper edge attenuation ramp, lower in-band insertion loss, better out-of-band rejection levels, and has compact structure. The center frequencies of dual bands are 2.4 GHz and 3.4 GHz, 3 dB bandwidths are 33 MHz and 32 MHz, and return loss is -36.36 dB and -36.07 dB. The first frequency band can be applied to the microwave interconnection access, and the second can be applied to WLAN, two passband has better isolation.

Compact High-Isolation Multiplexer With Wide Stopband Using Spiral Defected Ground Resonator

In this paper, the compact wide-stopband diplexer/triplexer is presented. The spiral defected ground resonator (SDGR) is analyzed by using the equivalent model. Based on the symmetry of the SDGR, a diplexer and a triplexer are implemented with a miniaturized size and a wide stopband. Each filter of the channels in the diplexer or triplexer can be independently controlled and exhibits a constant fractional bandwidth. To validate the design concept, the diplexer and the triplexer are designed, fabricated, and measured. The isolation between the channels is greater than 30 dB, and the measured out-of-band suppression is greater than 10 dB in the very wide frequency range. The measured results agree well with the simulation ones.

New Method for Zero Potential Non-stop Operation of Distribution Network Based on Injection Current

In the case of live working in the distribution network, a live method of live working that satisfies the requirements for personal safety and power supply reliability needs to be studied, because of the serious safety accidents caused by misuse and weak safety awareness. Based on the zero potential characteristics of the operating point, a new method based on injection current for zero-potential uninterrupted operation in distribution network is proposed. The Floyd algorithm is used to calculate the shortest electrical distance from the live working point to the substation, and the capacitance value of the ground is measured by the resonant grounding system, and the current value injected further to the neutral point is calculated. By regulating the zero-sequence voltage, the neutral point voltage is equal to the difference between the operating phase line voltage drop and the operating phase power supply voltage, ensuring that the operating point voltage is zero. Finally, based on the PSCAD simulation software, the system model is established. The simulation verifies the feasibility of the proposed method by comparing the voltage curves of the working phase.

Dual-band monopole antenna loaded with ELC metamaterial resonator for WiMAX and WLAN applications

In this paper, a miniaturized ELC (Electric-inductive-capacitive) based dual-band antenna is proposed for WiMAX and WLAN Applications. The designed antenna consists of a ring monopole antenna coupled with ELC resonator and partial rectangular ground plane, which is fed by 50Ω microstrip transmission line. ELC metamaterial modifies the current direction and yields dual-band characteristics. The band characteristics of the ELC metamaterial element are explained in detail. The proposed antenna with a compact size of 30 $$\times$$ 30 $$\times$$ 0.8 mm3 is fabricated on a FR-4 substrate of thickness of 0.8 mm, with relative dielectric constant $${{\mathbf{\varepsilon }}_{\mathbf{r}}}$$ = 4.4 and loss tangent $$\tan \varvec{\delta}$$ = 0.002. The experimental results cover the bandwidth of 500 MHz (3.57–4.04 GHz) and 860 MHz (4.73–5.59 GHz) with a resonance frequency of 3.74 and 5.1 GHz, respectively, which is suitable for WiMAX and WLAN applications.

Emergence of Kondo Resonance in Graphene Intercalated with Cerium.

The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, EF, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.

Fault Location in Resonant Grounded Network by Adaptive Control of Neutral-to-Earth Complex Impedance

This paper proposes a fault location method based on the adaptive control of neutral-to-earth complex impedance in a resonant grounded system, whose neutral point grounds are via an electromagnetic hybrid Petersen coil (EHPC). The EHPC can be equivalent to a parallel circuit of a negative resistance and an inductance, both of which can be adjusted. When a permanent single line-to-earth fault occurs, the ground-fault current will be compensated to almost zero, and the capacitance to earth and leakage resistance of system can be measured accurately for subsequent fault location. Then, the complex impedance of EHPC is adjusted, and the faulty feeder and its faulted section can be identified online based on the characteristics that the measurements of zero-sequence admittances of points along the faulty feeder change with the system's neutral-to-ground complex impedance. The detection criterion is certain and unique, without comparing all of the feeders. This paper also proposes an adaptive jitter adjustment and decoupling control of neutral-ground complex impedance by EHPC, which is adaptive to the grounding transient resistance and is repeatable, and can ensure that the magnitude of the zero-sequence parameter is large enough to be measured while without arc re-ignition, including in high impedance fault states. Simulations and experiments verified the feasibility of this fault location method and its control strategy.

MR-WPT With Reconfigurable Resonator and Ground for Laptop Application

A magnetic resonance wireless power transfer (MR-WPT) system with a reconfigurable planar receiver (Rx) to optimize transfer efficiency (TE) for laptop application has been investigated. The proposed MR-WPT system consists of a general four-coil system: a source coil and a transmitter Tx) coil in a Tx part and an Rx coil and a load coil in an Rx part. To enable performance comparison, the Rx coil uses either a rectangular loop resonator or a slit ground resonator (SGR) and both resonators are connected with a p-i-n diode to reconfigure and optimize the MR-WPT system’s TE along the transfer distance between the Tx and Rx parts. Mobile devices, including laptops, need a ground plane for practical use; therefore, the Rx coil is replaced by only an SGR, which operates as both a resonator and a ground. This letter, experimentally and theoretically proves that a reconfigurable MR-WPT system with an SGR has sufficient efficiency without the ferrite sheet typically used in practical MR-WPT applications.

A Decentralized Fault Detection Technique for Detecting Single Phase to Ground Faults in Power Distribution Systems With Resonant Grounding

This paper presents a decentralized fault detection technique for power distribution systems with resonant grounding. The aim of this paper is to detect single phase to ground faults and identify the faulty feeder within three cycles of the fault occurrence. In the proposed technique, faults are first detected based on the neutral voltage displacement. The pre-fault and post-fault voltages (phase to ground) are then used to identify the faulty phase. Finally, the faulty feeder (as well as the faulty area of a long feeder) is identified from the relationship between the initial transient of the zero-sequence current and the faulty phase voltage just after the occurrence of faults. A signal processing tool called mathematical morphology is utilized to identify the faulty feeder. To identify the faulty feeder, it is also required to know the fault occurrence time that is estimated using the slope of the neutral voltage. The main feature of the proposed scheme is that this technique only uses voltage and current signals from the corresponding voltage transformers and current transformers. Therefore, it does not require communication among protection devices in the same or different feeders to identify the faulty feeder. The proposed technique also has the ability to distinguish the nature of faults, i.e., whether the faults are permanent or temporary. The effectiveness of the proposed scheme is tested, on an IEEE test system as well as on a practical test system, using MATLAB/SimPowerSystems . Simulation results show that the proposed technique can quickly detect the single phase to ground faults in a resonant grounding power distribution system and identify the faulty feeder. It is also capable of distinguishing faults from other disturbances. Moreover, it works under different compensation levels as well as for different fault inception angles.

Differential Bandpass Filters Based on Dumbbell-Shaped Defected Ground Resonators

This letter presents a dumbbell-shaped defected ground resonator and its application in the design of differential filters. The operation principle of the dumbbell-shaped resonator (DSR) coupled to differential microstrip lines is studied through a circuit model analysis. The proposed circuit model is validated through the comparison with the electromagnetic simulation results. It is shown that the bandpass configuration of microstripline- coupled DSR can be used to design higher order bandpass filters. The design procedure is explained by developing a thirdorder filter prototype. The designed filter shows more than 57 dB common mode rejection within the differential passband.

Deep-Learning-Based Earth Fault Detection Using Continuous Wavelet Transform and Convolutional Neural Network in Resonant Grounding Distribution Systems

Feature extraction for fault signals is critical and difficult in all kinds of fault detection schemes. A novel simple and effective method of faulty feeder detection in resonant grounding distribution systems based on the continuous wavelet transform (CWT) and convolutional neural network (CNN) is presented in this paper. The time-frequency gray scale images are acquired by applying the CWT to the collected transient zero-sequence current signals of the faulty feeder and sound feeders. The features of the gray scale image will be extracted adaptively by the CNN, which is trained by a large number of gray scale images under various kinds of fault conditions and factors. The features extraction and the faulty feeder detection can be implemented by the trained CNN simultaneously. As a comparison, two faulty feeder detection methods based on artificial feature extraction and traditional machine learning are introduced. A practical resonant grounding distribution system is simulated in power systems computer aided design/electromagnetic transients including DC, the effectiveness and performance of the proposed faulty feeder detection method is compared and verified under different fault circumstances.

A miniaturised directive high gain metamaterial antenna using ELC ground for WiMAX application

ABSTRACTThis article presents a compact directional high gain metamaterial antenna using electric-field-driven LC (ELC) resonator ground plane. The ELC ground plane is accountable for good directivity and proper impedance matching at first-order resonance (FOR) frequency of 5.4 GHz. This work offers compactness with patch electrical size of 0.228 λ0 × 0.230 λ0, where λ0 is the free space wavelength at FOR frequency. At the FOR frequency, proposed antenna offers a gain of 6.31 dB in broadside direction. High gain of the proposed antenna makes it suitable for WiMAX applications. Modelling of the proposed antenna is carried out using ANSYS HFSS 14.0, 3D simulation software and results are verified by the fabricated prototype. Measured and simulated results are in good agreement.