Operation Analysis of Electromagnetic Loop Network in Distribution Network Based on Physical Test and Simulation

The objective of this paper is to present an approach for isolating the harmonic contents in both voltage and current waveforms of the montage feeder of Gharb Talkha substation (60/11 KV). A novel technique using Discrete Wavelet transform (DWT) for the analysis of the waveforms harmonics content At the beginning the substation is simulated using Simulink toolbox in Matlab program with and without the presence of capacitor bunk. The obtained voltage and current waveforms are compared to the actual data. The proposed model is used to study the effect of replacing the capacitor bank with single tuned parallel passive filter. The resulting current and voltage waveforms are analyzed using the proposed DWT technique. The analysis showed that the Total Harmonic Distortion (THD) of both voltage and current waveforms is improved as well as the power factor.

The accuracy and stability of front-end point cloud registration algorithms are crucial for the mapping and localization precision in laser SLAM (simultaneous localization and mapping) systems. Traditional point-to-line and point-to-plane iterative closest point (ICP) registration algorithms, widely used in SLAM front ends, often suffer from low efficiency, significant data dependency during the matching process, and a propensity for local optima. This registration method exhibits a more pronounced local optimum issue in large-scale SLAM mapping, thereby diminishing matching accuracy and increasing reliance on initial values. To address these limitations, this paper introduces NI-LIO, a novel SLAM algorithm that integrates ICP with normal distributions transform (NDT) to enhance localization accuracy, computational efficiency and robustness. By combining the precision of ICP with the robustness of NDT, the proposed algorithm significantly improves system stability and localization accuracy. The analysis of mapping and localization experiments indicates a significant reduction in errors compared to traditional SLAM algorithms, with experiments showing a REMS value decrease of over 20%. Compared to ALOAM, FAST_LIO2 and Lego-LOAM algorithms, the new NI-LIO algorithm shows improvements in both accuracy and stability, enabling the construction of a more precise and consistent global map. This algorithm exhibits excellent adaptability to various environments.

Pantograph arcing with AC supply generates transients, cause asymmetries and distortion in supply voltage and current waveforms and can damage the pantograph and the overhead contact line. The asymmetry generates a net dc component and harmonics, which propagate within the traction power and signalling system and causes electromagnetic interference. Unlike DC-fed systems (Part I), the arcing in ac supply is complex because of the zero crossing of currents and voltages. In this paper, we discuss the mechanisms of sliding contact and arcing between pantograph-contact wire using the experimental setup described in Part I. Influences of various parameters and test conditions on arcing phenomenon and their signature patterns on the supply voltage and current waveforms are presented. It is shown how the arcing mechanism and corresponding asymmetry in the voltage and current waveforms are governed by line speed, current, supply voltage, inductive load, and pantograph material. The asymmetry in the current waveform is mainly due to the difference in the duration of successive zero-current regions and uneven distortion of the waveshapes. This, in turn, creates the asymmetry in the voltage waveform. The findings presented in this paper could be beneficial for coming up with appropriate mitigation techniques from the electromagnetic interference due to pantograph arcing in AC traction systems.

Conventional pumped storage units require fast and accurate grid connection to reduce the impact on the units during grid connection. This article first analyzes the principle and allowable conditions of quasi synchronous grid connection of the unit, and theoretically analyzes the impact of voltage difference, frequency difference, and phase angle difference on the unit's impulse current during the grid connection process. Secondly, this article uses Simulink software to build a single machine grid connected simulation model with quasi synchronous modules. Finally, this article conducted simulation analysis on the changes in impulse current during grid connection of the unit with three different conditions: voltage difference, frequency difference, and phase angle difference, providing guidance for the synchronous grid connection of the pumped storage unit.

An experimental investigation of a TRAPATT diode with its oscillator circuit is presented. The measurements of current and voltage waveforms were made with a sampling oscilloscope (3 dB bandwidth, 14 GHz)and an improved capacitive voltage-divider probe. Design information is given for this type of probe which can have an almost unlimited bandwidth. Voltage and current waveforms across the semiconductor chip are presented for a diode that oscillated at 1 GHz with an efficiency of 49%. It is shown that the mode of operation and the waveforms are explained well by a simple theoretical model that has been developed.

In this chapter, we shall discuss techniques used to fit faulted current and voltage waveforms, each to a sinusoidal waveform containing a fundamental component, a decaying/constant direct current (DC) component and/or harmonics.These techniques use the least squares (LSQ) method to minimise the fitting error, and all have the common goal of extracting the fundamental components of voltage and current waveforms, to calculate the impedance to the fault or the comparison of current-based signals in digital differential protection.

Voltage source inverter (VSI) had been used in dc traction power substation to deliver the trains braking energy back to the utility grid. To mitigate low order harmonics components, pulse-width-modulation (PWM) technique is commonly used in VSI controlled. As a result, the ac voltage and current waveforms may contain high frequency ripples. This paper proposes to mitigate the high frequency harmonics using LCL-filter with series <em>R</em>-damper. This filter offers good attenuation on harmonics with smaller size compare to other passive filter topologies. Theoretical analysis and simulation verification are conducted in designing the proposed filter. System level simulation had also been carried out. Sinusoidal grid current and voltage waveforms are recorded (THD<2%). This paper also includes damping losses analysis in conjunction with resonance peak suppression in designing the <em>R</em>-damper.

When the soil invaded by water as the grounding medium in green power generation sites near river basins, on the coast, is dominantly characterized in terms of its resistivity, the characteristics of the voltage and current waveforms on transient discharges such as the soil can be experimentally investigated using the liquid gap, reproducing the resistivity of the soil. The transient discharge characteristics is available information on the surge withstand rating of surge protective devices used in the green power generation sites. Experimental results on the behaviour of lightning impulse discharges in a tap-water gap are reported; these results show that the resistivity of tap water is nearly equal to those of a river and cultivated and marshy land. Further, (1) the discharge voltage and current waveforms indicate the periodic attenuated waveforms for one period, and the voltage waveforms indicate amplitude distortions; (2) the discharge impedance obtained using the fitting curves to the discharge waveforms ranges from 1 to 2.5 times that of the tap-water resistance, i.e., 80Ω, and from 8 to 3.2 times that for positive and negative rod discharges.

The efficacy of a cellular approach to resilience-oriented operation of distribution grids based on eigenvectors of the Laplacian matrix

This paper analyses harmonic emission of different light-emitting diode (LED) lighting systems. Basic mathematical analysis of harmonic emission was presented. Paper deals with single LED lights (bulbs) and street lighting systems formed by luminaries. Harmonic emission results were obtained by measurement. More, single LED bulbs were modeled within EMTP-ATP software. Comparison of measured results and results obtained by simulation was performed. Further, one LED lighting system was compared with sodium lighting system in the harmonic emission area. Comparison was performed by replacing one sodium lighting system (in one street) with appropriate LED lighting system. Standards which deals with harmonic emission were presented and compared. More, obtained results of harmonic emission were compared with valid Standards. The goal of paper is to compare harmonic emission of various bulbs and on other side to analyze LED lighting systems with luminaries. It is important because today there are various LED lights in market made by various companies. It is due high share penetration of LED lighting in each area and their implementation in: house, buildings, business areas, factories, street lighting systems etc. On other side, LED lights are nonlinear loads which potentially can have negative effect on distribution grid. One more goal is to compare measured results and the results obtained by modeling. Correctly modeled LED lighting can be used in various research. It can be used to improve the manufacturing process of LED lights.

Conformational changes are crucial for the catalytic action of many enzymes. A prototypical and well-studied example is loop opening and closure in triosephosphate isomerase (TIM), which is thought to determine the rate of catalytic turnover in many circumstances. Specifically, TIM loop 6 "grips" the phosphodianion of the substrate and, together with a change in loop 7, sets up the TIM active site for efficient catalysis. Crystal structures of TIM typically show an open or a closed conformation of loop 6, with the tip of the loop moving ∼7 Å between conformations. Many studies have interpreted this motion as a two-state, rigid-body transition. Here, we use extensive molecular dynamics simulations, with both conventional and enhanced sampling techniques, to analyze loop motion in apo and substrate-bound TIM in detail, using five crystal structures of the dimeric TIM from Saccharomyces cerevisiae. We find that loop 6 is highly flexible and samples multiple conformational states. Empirical valence bond simulations of the first reaction step show that slight displacements away from the fully closed-loop conformation can be sufficient to abolish most of the catalytic activity; full closure is required for efficient reaction. The conformational change of the loops in TIM is thus not a simple "open and shut" case and is crucial for its catalytic action. Our detailed analysis of loop motion in a highly efficient enzyme highlights the complexity of loop conformational changes and their role in biological catalysis.

The Unified Power Quality Compensator (UPQC) is one of the most widely studied Custom Power Devices (CPDs) as it is a single solution for mitigating voltage and current-related abnormalities in a distribution grid, which may arise due to increased use of non-linear loads and integration of renewable energy sources. In this paper, a popular control method of the UPQC – the synchronous reference frame (SRF) method – is tested in a 415 V distribution system, and the system performance is observed and analyzed in a MATLAB-Simulink environment, using the SimPowerSystems Toolbox. The outcome of this was discussed and analysed, the finding of this paper may help understand as to why UPQC is a heavily researched topic in the field of power quality. An efficacy can be determined of a popular control scheme pertaining to this device by analyzing the voltage and current waveforms before and after the deployment of UPQC into the system.KeywordsCustom Power Devices (CPDs)Distribution STATic COMpensator (DSTATCOM)Dynamic Voltage Restorer (DVR)Power qualitySynchronous Reference Frame (SRF) theoryUnified Power Quality Compensator (UPQC)

We study the multi-robots collaborating under controlled by the same worksite. And a Sherwood algorithm approach based on dynamic area for the multi-robots Simultaneous Localization and Mapping (SLAM) problem is proposed. It can calculate the location of the robots in the joint map by Sherwood algorithm. This task can be done with using a collection of the environment features of their own planar surface on which these robots are moving. The theoretical analysis and results of experiments show that the mapping of the dynamic area can greatly improve exploring efficiency and Sherwood algorithm can enhance the real-time of localization of each robot.

The present methods used to calibrate an active power or energy meter device under test (DUT) under nonsinusoidal conditions are based on a limited number of current and voltage waveforms and do not exercise the dynamic range of the DUT. After reviewing a method recently developed at the National Physical Laboratory (NPL) to exercise the dynamic range of a DUT under sinusoidal and nonsinusoidal conditions for specified current and voltage waveforms, the paper reports on the performance of the DUT under nonsinusoidal conditions measured using the NPL method. Experimental results: 1) verify theoretical predictions that the active power fractional full-scale (FS) error depends on both the phase-angle group between the current and voltage waveforms and the phase angle between the harmonics and the fundamental of both the current and voltage waveforms and 2) show that the active power fractional FS error for sinewave excitation can be larger than that for nonsinusoidal conditions

This paper introduces the power quality analysis of unidirectional and bidirectional ac voltages controllers. An AC voltage regulator coupled between the power supply and the load is a device having major components of two thyristors connected in inverse parallel manner and the power flow is controlled by varying the firing angle of thyristors. For each configuration, the experimental setup is implemented on Feedback Power Electronics Trainer and simulation is done using MATLAB/Simulink. The simulated and experimental waveforms of current and voltage in case of resistive and inductive loads are obtained by taking different firing angles and are correlated, which demonstrate the effectiveness of model and its configurations. Due to switching operations of power electronic converters, they contain nonlinearities and generate harmonics which not only disturb the performance of converters but also the quality of input power system is badly affected. The power quality factor is observed by Fluke Power Quality Analyzer that can monetize the cost of energy waste due to poor quality. In this research, the performance evaluation of controller with industrial inductive loads under different delaying angle is investigated and detailed comparative analysis is done by experimental readings and simulation results. Total Harmonic Distortion (THD) analysis for different waveforms of voltage and current, its calculation and comparison for change in loads have been presented in this paper.