Accurate Power Sharing in Proportion for Parallel Connected Inverters by Reconstructing Inverter Output Impedance

Shengli Huang,Jianguo Luo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents parallel-connected inverters to achieve accurate proportional power sharing. Due to line impedance mismatch, reactive power cannot be distributed proportionally when using the conventional P-ω and Q-E droop. In order to realize reactive proportional power sharing, the ratio of the droop coefficients should be inversely proportional to their power-sharing ratios. Meanwhile, the ratio of the line impedance should be inversely proportional to the desired power-sharing ratio, which is very difficult to be met in practice. In order to deal with this issue, a practical control strategy is presented. By measuring the PCC voltage and using the virtual impedance, the output impedance of individual inverters is reconstructed to counteract the line impedance effect. In order to guarantee system stability, a low pass filter is designed to suppress the bandwidth of the line compensation. Finally, the simulation and experimental results are given to verify the effectiveness of the proposed control strategy.

Multi-Function Distributed Generation with Active Power Filter and Reactive Power Compensator

Shengli Huang,Jianguo Luo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

Accurate Power Sharing in Proportion for Parallel Connected Inverters by Reconstructing Inverter Output Impedance

Huang, Shengli,Luo, Jianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents parallel-connected inverters to achieve accurate proportional power sharing. Due to line impedance mismatch, reactive power cannot be distributed proportionally when using the conventional $P-{\omega}$ and $\mathcal{Q}-E$ droop. In order to realize reactive proportional power sharing, the ratio of the droop coefficients should be inversely proportional to their power-sharing ratios. Meanwhile, the ratio of the line impedance should be inversely proportional to the desired power-sharing ratio, which is very difficult to be met in practice. In order to deal with this issue, a practical control strategy is presented. By measuring the PCC voltage and using the virtual impedance, the output impedance of individual inverters is reconstructed to counteract the line impedance effect. In order to guarantee system stability, a low pass filter is designed to suppress the bandwidth of the line compensation. Finally, the simulation and experimental results are given to verify the effectiveness of the proposed control strategy.

Multi-Function Distributed Generation with Active Power Filter and Reactive Power Compensator

Huang, Shengli,Luo, Jianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

The microstructure evolution and mechanical properties of ammonium polyphosphate/ aluminium hydroxide/ mica during thermal reaction

Sheng HU,Fei Chen,Jun-Guo Li,Qiang Shen,Zhi-Xiong Huang,Lian-Meng Zhang 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.8

The phase and microstructure evolution of ammonium polyphosphate/ aluminium hydroxide/ mica compounds (AAM) duringthermal reaction are investigated. At 300 oC, AAM residues exhibit porous structure due to gas evolution from the thermaldecomposition of ammonium polyphosphate (APP) and aluminium hydroxide, but mica does not react with them, and theflexural strength of specimens can reach 11.56 MPa. The thermal decomposition products of APP react with AlOOH toNH4AlP2O7, which can improve the flexural strength during 300 ~ 400 oC. The reactivity of mica is increased by eliminatinghydroxyl at temperature up to 600 oC, and the flexural strength of AAM residues is improved furtherly by the chemicallyinteractions between active mica and phosphates during 600 ~ 1000 oC. And specifically at 1000 oC, the AAM residues exhibitrelatively high flexural strength, which can reach 26.85 MPa and reactions between mica and KAlP2O7 could generateKAlSi3O8 and 3Al2O3·2SiO2. AAM with high flexural strength from low to high temperatures is expected to be a kind ofexcellent inorganic additive of ceramifiable polymer with wide temperature range for using.

Two mitochondrial genomes of genus Megacampsomeris Betrem, 1928 (Hymenoptera: Scoliidae) with their phylogenetic implications

Huang Li-Sheng,Liu Zhen,Chen Hua-Yan,Chen Xue-Xin 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

We determined two mitochondrial genomes of genus Megacampsomeris Betrem, 1928, i.e., M. binghami (Betrem, 1928) with 16,461 bp and M. farrenwhitei (Betrem, 1928) with 15,834 bp in length respectively and anotated the sequence of M. prismatica (Smith, 1855). These sequence all possess 37 mitochondrial genes, containing 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs) including one extra trnM gene while missing trnK gene, and two ribosomal RNA (rRNA) genes separately. Gene rearrangement showed inversion event involing protein-coding and tRNA genes. The protein-coding genes of 18 species representing seven superfamilies and 12 families from Aculeata were used for phylogenetic analysis by maximum likelihood (ML) analysis and Bayesian inference (BI), with Cotesia vestalis from Braconidae and Hyposoter sp. from Ichneumonidae was as outgroups. M. prismatica was more closer to M. binghami than M. farrenwhitei in our inferences. Consistent with previous studies, our results supported paraphyly of the superfamily Chrysidoidea and a sister group relationship between Formicoidea and Vespoidea, but failed to recover the monophyly of superfamilies Apoidea and Pompiloidea.

Preparation and Characterization of Proton Conductive Phosphosilicate Membranes Based on Inorganic-Organic Hybrid Materials

Huang, Sheng-Jian,Lee, Hoi-Kwan,Kang, Won-Ho Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.2

A series of proton conductive inorganic-organic hybrid membranes doped with phosphoric acid ($H_3PO_4$) and/or triethylphosphate (PO(OEt)$_3$) have been prepared by sol-gel process with 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0 ${\times}$ $10^{-3}$ S/cm with composition of 50TEOS-30GPTMS-20APTES-50$H_3PO_4$ was obtained at 120 ${^{\circ}C}$ under 50% relative humidity. Thermal stability of membrane was significantly enhanced by the presence of SiO$_2$ framework up to 250 ${^{\circ}C}$. XRD revealed that the gels are amorphous. IR spectra showed a good complexation of $H_3PO_4$ in the matrix. The conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in concentration of defected site in hybrid matrix. The effect of PO(OEt)$_3$, humidifying time, and heat-treatment were also investigated. PO(OEt)$_3$ had no improvement on conductivity and conductivity increased with humidifying time, however, decreased with heating temperature.

A Lithium-Ion Batteries Fault Diagnosis Method for Accurate Coulomb Counting State-of-Charge Estimation

Huang Cong-Sheng 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Real-time and accurate estimating state-of-charge (SOC) of a lithium-ion battery is a critical but technically challenging task for battery management systems. Coulomb counting algorithm is an efective real-time SOC estimation algorithm but sufers from three typical faults: initial SOC fault, battery capacity fault, and biased load current measurement fault, making its estimation accuracy challenging in practice. To solve the above-mentioned problem, this paper proposes a model-based fault diagnosis algorithm for the Coulomb counting algorithm. The proposed algorithm efectively diagnoses the faults, where the diagnosis requires merely the load current and the terminal voltage of the battery without extra measurements or prior knowledge of the battery. Also, this algorithm is performed alongside the Coulomb counting algorithm either intermittently or remotely in the cloud to ensure the real-time SOC estimation feature of the Coulomb counting algorithm. To showcase the performance of the proposed algorithm, two experiments: a battery discharging experiment using a standard electric vehicle driving profle and a Monte Carlos experiment were performed. Both experiments well-demonstrate the efectiveness of the proposed battery electric circuit model-based SOC estimation algorithm in diagnosing the three typical faults of the Coulomb counting algorithm with 100% true-positive rates.

Effect of surface bolt on the collapse mechanism of a shallow rectangular cavity

Huang, Fu,Zhao, Lian-heng,Zhang, Sheng Techno-Press 2017 Geomechanics & engineering Vol.13 No.3

Based on the collapse characteristics of a shallow rectangular cavity, a three-dimensional failure mechanism which can be used to study the collapsing region of the rock mass above a shallow cavity roof is constructed. Considering the effects of surcharge pressure and surface bolt on the collapsing block, the external rate of works produced by surcharge pressure and surface bolt are included in the energy dissipation calculation. Using variational approach, an analytic expression of surface equation for the collapsing block, which can be used to study the collapsing region of the rock mass above a shallow cavity roof, is derived in the framework of upper bound theorem. Based on the analytic expression of surface equation, the shape of the collapsing block for shallow cavity is drawn. Moreover, the changing law of the collapsing region for different parameters indicates that the collapsing region of rock mass decreases with the increase of the density of surface bolt. This conclusion can provide reference for practicing geotechnical engineers to achieve an optimal design of supporting structure for a shallow cavity.

Strength failure behavior of granite containing two holes under Brazilian test

Huang, Yan-Hua,Yang, Sheng-Qi,Zhang, Chun-Shun Techno-Press 2017 Geomechanics & engineering Vol.12 No.6

A series of Brazilian tests under diameter compression for disc specimens was carried out to investigate the strength and failure behavior by using acoustic emission (AE) and photography monitoring technique. On the basis of experimental results, load-displacement curves, AE counts, real-time crack evolution process, failure modes and strength property of granite specimens containing two pre-existing holes were analyzed in detail. Two typical types of load-displacement curves are identified, i.e., sudden instability (type I) and progressive failure (type II). In accordance with the two types of load-displacement curves, the AE events also have different responses. The present experiments on disc specimens containing two pre-existing holes under Brazilian test reveal four distinct failure modes, including diametrical splitting failure mode (mode I), one crack coalescence failure mode (mode II), two crack coalescences failure mode (mode III) and no crack coalescence failure mode (mode IV). Compared with intact granite specimen, the disc specimen containing two holes fails with lower strength, which is closely related to the bridge angle. The failure strength of pre-holed specimen first decreases and then increases with the bridge angle. Finally, a preliminary interpretation was proposed to explain the strength evolution law of granite specimen containing two holes based on the microscopic observation of fracture plane.