The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Hu, Jian,Fu, Lijun The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

QTL Analysis of Floral Traits of Rice (Oryza Sativa L.) under Well-Watered and Drought Stress Conditions

Hu Songping,Zhou Ying,Zhang Lin,Zhu Xudong,Wang Zhenggong,Li Lin,Luo Lijun,Zhou Qingming 한국유전학회 2009 Genes & Genomics Vol.31 No.2

Three floral traits, spikelet number per panicle (SNP), percentage of single exserted stigma (PSES) and dual exserted stigma (PDES) of a RI population with 185 lines under water stress and non-stress conditions for two years were investigated in a drought tolerance screening facility. ANOVA results showed high significance between years, lines, and water stress treatments, together with interactions among them in pairs. High phenotypic correlation was found between PSES and PDES (r = 0.5424***). Based on a linkage map of 203 SSR markers, when under well-watered condition, six QTLs ( qSNP-3b, qSNP-4, qSNP-11 qSNP-2, qSNP-5 and qSNP-9) were detected for SNP. Half of them had significant Q× E interactions. Three QTLs ( qPSES-1, qPSES-2, qPSES-5) were found to influence PSES, including one locus ( qPSES-2) having Q× E interaction. And three QTLs ( qPDES-2, qPDES-5 and qPDES-8) were also detected to influence PDES. qPDES-5 was found to have Q × E interaction. The contribution rate of a single QTL varied from 0.80% to 8.83% for additive effect, and 1.86% to 15.25% for Q × E interactions. Under drought stress, six QTLs ( qSNP-3a, qSNP-4, qSNP-7a, qSNP-7b, qSNP-8 and qSNP-9) were associated with SNP, including qSNP-3a and qSNP-4 with Q × E interaction. Three QTLs ( qPSES-1, qPSES-10 and qPSES-12) were located on rice chromosome 1, 10 and 12 for PSES. Four QTLs ( qPDES-1a, qPDES-1b, qPDES-4 and qPDES-9) were detected for PDES, including qPDES-9 with Q ×E interaction. The additive effect of single QTL can only explain 1.16% to 5.84% of total variance while Q × E interaction of four loci can explain 4.25% to 11.54% of total variance for each locus. There were one to nine pairs of epistatic QTLs influencing SNP and stigma exsertion. The contribution rates of additive and epistatic effects seemed to be in a low magnitude for most cases (0.76%~9.92%) while a few QTLs or QTL pairs explained more than 10% of total variance. Some main effect QTL and epistasis were commonly detected among PSES and PDES, explaining the high positive correlation between them. Few QTLs were detected under both water stress and non-stress conditions, indicating that drought had severe impact on the genetic behaviors of both spikelet number and stigma exsertion. Three floral traits, spikelet number per panicle (SNP), percentage of single exserted stigma (PSES) and dual exserted stigma (PDES) of a RI population with 185 lines under water stress and non-stress conditions for two years were investigated in a drought tolerance screening facility. ANOVA results showed high significance between years, lines, and water stress treatments, together with interactions among them in pairs. High phenotypic correlation was found between PSES and PDES (r = 0.5424***). Based on a linkage map of 203 SSR markers, when under well-watered condition, six QTLs ( qSNP-3b, qSNP-4, qSNP-11 qSNP-2, qSNP-5 and qSNP-9) were detected for SNP. Half of them had significant Q× E interactions. Three QTLs ( qPSES-1, qPSES-2, qPSES-5) were found to influence PSES, including one locus ( qPSES-2) having Q× E interaction. And three QTLs ( qPDES-2, qPDES-5 and qPDES-8) were also detected to influence PDES. qPDES-5 was found to have Q × E interaction. The contribution rate of a single QTL varied from 0.80% to 8.83% for additive effect, and 1.86% to 15.25% for Q × E interactions. Under drought stress, six QTLs ( qSNP-3a, qSNP-4, qSNP-7a, qSNP-7b, qSNP-8 and qSNP-9) were associated with SNP, including qSNP-3a and qSNP-4 with Q × E interaction. Three QTLs ( qPSES-1, qPSES-10 and qPSES-12) were located on rice chromosome 1, 10 and 12 for PSES. Four QTLs ( qPDES-1a, qPDES-1b, qPDES-4 and qPDES-9) were detected for PDES, including qPDES-9 with Q ×E interaction. The additive effect of single QTL can only explain 1.16% to 5.84% of total variance while Q × E interaction of four loci can explain 4.25% to 11.54% of total variance for each locus. There were one to nine pairs of epistatic QTLs influencing SNP and stigma exsertion. The contribution rates of additive and epistatic effects seemed to be in a low magnitude for most cases (0.76%~9.92%) while a few QTLs or QTL pairs explained more than 10% of total variance. Some main effect QTL and epistasis were commonly detected among PSES and PDES, explaining the high positive correlation between them. Few QTLs were detected under both water stress and non-stress conditions, indicating that drought had severe impact on the genetic behaviors of both spikelet number and stigma exsertion.

Performance of Tunnel Feet-Lock Pipe (TFP) in Sharing Vertical Foundation Load

Lijun Chen,Jianxun Chen,Yao Li,Yanbin Luo,Yongjun Mu,Taotao Hu,Chuanwu Wang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.3

During the tunnel construction in soft ground, the insufficient bearing capacity of tunnel foundation usually causes a series of settlement problems. Tunnel feet-lock pipe (TFP) has been widely used to take the vertical load acting at the foundation of a tunnel foot. However, the detailed bearing performance of TFP is still not clear, and there is a lack of quantitative research. In this paper, a simple analytical approach is adopted to evaluate the performance of the TFP, and the main parameters affecting the supporting performance of the TFP are analyzed. The results show that the ϕ42 − ϕ140 TFP with the angle of 10° can take 3.8% −40.4% of vertical load. TFP has an effective length of 1.7 m − 2.8 m, which is related to the relative stiffness between the TFP and the stratum. With the increase of the installation angle, the TFP shares more vertical load. This trend is more obvious when the angle of the TFP is greater than 20°. If the proportion coefficient of the subgrade reaction coefficient is doubled, the vertical load shared by the TFP can be increased by 34% − 38%. For every 10 cm increase in overbreak behind the steel rib, the vertical load shared by TFP is reduced by 16%.

The Relatedness Between Graphene Oxide Lateral Size and the Mechanical Properties of Calcium Alginate Composite Fibers

Lijun Jin,Yiqi Wu,Xinjun Hu,Qinjia Chen,Yue Lu,Yongxiao Bai 한국섬유공학회 2023 Fibers and polymers Vol.24 No.2

It is widely recognized that combining alginate with graphene oxide (GO) is an effective method in improving the propertiesof alginate fiber. However, how the lateral size of GO influences the properties of the composite fiber is still unclear. Inthis work, GO was separated into four kinds of different lateral sizes with the assistance of centrifugation and high-powerultrasound. The tensile strength of calcium alginate/graphene oxide (CaAlg/GO) composite fiber increased with the lateralsize of GO. Surprisingly, the combination of large and small GO performed the superior reinforcement effect. The tensilestrength and Young’s modulus increased from 407.66 MPa and 13.87 GPa to 556.97 MPa and 20.57 GPa, respectively. Inaddition, the water absorption ability of CaAlg/GO composite fiber reduced with the decreasing of the lateral size of GO. With significantly improved mechanical properties and fine biocompatibility, the CaAlg/GO composite fibers may havepotential applications in the biotechnological, biomedical, and tissue engineering areas.

Preparation of Polyvinylpyrrolidone-Stabilized Fe0 Nanoparticles for Remediation of Cr(vi)-Spiked Soil

Lijun Yan,Chen He,Xuefeng Hu,Kokyo Oh 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Stability Control of Energy Storage Voltage Source Inverters in Isolated Power Systems

Hu, Jian,Fu, Lijun The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

Stability Control of Energy Storage Voltage Source Inverters in Isolated Power Systems

Jian Hu,Lijun Fu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Jian Hu,Lijun Fu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

From Carbon-Based Nanotubes to Nanocages for Advanced Energy Conversion and Storage

Qiang Wu,Lijun Yang,Xizhang Wang,Zheng Hu 한국진공학회 2018 한국진공학회 학술발표회초록집 Vol.2018 No.8

Enhanced bone regeneration using poly(trimethylene carbonate)/ vancomycin hydrochloride porous microsphere scaffolds in presence of the silane coupling agent modified hydroxyapatite nanoparticles

Jian He,Xulin Hu,Luyao Xing,Dongliang Chen,Lijun Peng,Gaofeng Liang,Chengdong Xiong,Xiangchun Zhang,Lifang Zhang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-

Tissue-engineered scaffolds acted as active natural extracellular matrices that allowed for cellattachment, migration, proliferation, and differentiation. To enhance the drug loading, degradationcontrol, and mechanical features of tissue-engineered scaffolds used in bone regeneration applications,we synthesized novel poly(trimethylene carbonate) (PTMC)/modified HA nanoparticles (KHA NPs,modified by silane coupling agent)/vancomycin hydrochloride (VH) porous microspheres scaffold. Thefabricated PTMC/KHA/VH scaffold has unique surface corrosion degradation, excellent surface properties,and high cytocompatibility. The novel PTMC/KHA/VH scaffold was characterized by 42% porosity,100 mmpore size, and 208.2 MPa compressive modulus. After the treatment of a rat femur defect for 4, 8, and 12weeks, the surface corrosion biodegraded of the PTMC/KHA/VH scaffold remarkably decreasedinflammation response and promoted bone regeneration, suggesting its use as a bioactive structurein bone tissue engineering.