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An Improved Inverter-Side Current Feedback Control for Grid-Connected Inverters with LCL Filters
Jinming Xu,Shaojun Xie,Jiarong Kan,Lin Ji 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The grid-connected LCL-filtered inverter is widely used in distributed power generation systems based on renewable energies. Single inverter-side current feedback control only needs to sample one current to realize both current control and inverter protection. However, with single inverter-side current feedback control, the closedloop system is under-damped or even unstable due to the digital control delay. In this paper, an active damping control based on only inverter-side current feedback is proposed. With the novel control, the resonance in the digitally-controlled LCL-filtered inverter is successfully solved while only inverter-side current is sampled. Comparisons of the proposed and typical single inverterside current feedback control have verified the improvement of the proposed control. Thus, the proposed control has good application prospect in grid-connected LCL-filtered inverters.
Jinming Xu,Shenyiyang Bian,Qiang Qian,Jiarong Kan,Shaojun Xie 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Phase-locked loops (PLLs) are the key technique for inverters to be synchronized with the PCC voltage. Typically, in the single-phase applications, the delaybased PLL is being widely used. However, for nowadays applications where the inverter may be connected to the PCC with large grid impedance, the inverter performance can be endangered, and harmonics or even instabilities are aroused. Although there are some relevant literatures, the solutions for solving the adverse impacts of delay-PLL on the system performance are still not well documented. Therefore, this paper aims to study the limitations of delay-based PLL and provide an improved approach. Through the inverter output impedance modelling, the reason why the delay-based PLL causes the instability in the weak grid case has been clearly explained. Then, the way to solve the instability caused by the PLL has been discussed, and an improved delay-based PLL has been proposed to improve the weak grid compatibility of inverters. The single-phase inverter system can then work well when the grid impedance varies widely.
A Method for Missing Data Recovery of Waste Gas Monitoring in Animal Building Based on GA-SVM
Jinming Liu,Qiuju Xie,Yuanyuan Zhang 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.5
In order to solve the data missing problem caused by sensor faults during the waste gas monitoring in animal building, a method for missing data recovery was presented based on support vector machine (SVM) combined with genetic algorithm (GA). Multiple factors that influence monitoring values of the waste gas in animal building such as temporal, spatial and environmental, were considered to established a SVM regression prediction model to estimate the missing data of the waste gas monitoring. Meanwhile, to obtain better prediction accuracy, model parameters were optimized by the GA. The data processing of the ammonia (NH3) concentration was taken as an example; monitoring data of 3 days were randomly selected in a farm to test the presented model in this paper. It is shown that there was a very little error between the estimated data and the monitoring data, the maximal relative error was 6.99 % (percent), and the average relative error was 2.15 % (percent). It is an effective method for missing data recovery and a practical way of data processing for waste gas monitoring in animal building.
A Method for Missing Data Recovery of Air Pollutants Monitoring in Henhouse Based on QGSA-SVM
Jinming Liu,Qiuju Xie,Guiyang Liu,Yong Sun 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.3
To solve the data missing problem caused by sensor faults during the air pollutants monitoring in henhouse, a method for missing data recovery was proposed based on support vector machine (SVM). Multiple factors that influence monitoring values of the air pollutants in henhouse, such as temporal, spatial and environmental, were considered to established a SVM regression model to estimate the missing data of the air pollutants monitoring. Meanwhile, to obtain better prediction accuracy, regression model parameters were optimized by a novel hybrid optimization algorithm which was combined standard genetic algorithm with quantum genetic strategy and simulated annealing tactics. Taking the data processing of the ammonia (NH3) concentration as an example, the proposed method was tested with the monitoring data of 3 days in a farm. The estimation results of missing data shown that there was a litter error between the estimated data and monitoring data, the maximal relative error was 5.87% (percent), the average relative error was 1.77% (percent). It is verified that this method of missing data recovery is feasible and valid.
Current utilization of waste biomass as filler for wood adhesives: A review
Jinming Liu,Yongfeng Li,Hailin Mo,Enjun Xie,Jianlin Fang,Weixing Gan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
Filler is one of the most important additives for wood adhesives. The introduction of filler offers variousfunctions for wood adhesives, such as the increase of initial viscosity, the decrease of permeability, theimprovement of bonding strength, and the reduction of production cost. However, flour, a grain resource,is widely used as a filler that is added to polymers in the production of wood-based panels. As a result, alarge number of edible resources are wasted every year. Waste biomass that biomass residues are abandonedin nature are a promising filler that can be used to replace flour. The utilization of waste biomass asfiller for wood adhesives to prepare wood-based panels not only improves its mechanical strength, butalso reduces formaldehyde emissions. However, most waste biomass shows disappointing prepressingproperties. Advances in the use of waste biomass as an alternative filler for wood adhesives werereviewed. In addition, the current limitations and future prospects of waste biomass were discussed. Recycling waste biomass is a useful way to avoid the enormous amount of waste generated by differentindustries and control environmental pollution. It contributes to the practical development of circulareconomy.
Jinming Xu,Shaojun Xie,Jiarong Kan,Binfeng Zhang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
For grid-connected LCL-filtered inverter, the inherent resonance of LCL filter endangers the stability so that the inverter is hard to be controlled. To solve the resonance, the capacitor-current-feedback active damping (AD) is welcomed. However, the digital control delay was not seriously considered in the previous studies. The research on the stability with such control considering the digital control delay is lacking. Thus, this paper aims to provide a deep analysis of the capacitor-current-feedback AD in a digitally-controlled inverter. A stable region is derived. It is proved that the stable region for the capacitor-current- feedback AD is closely related to the sampling and computation delay, the control frequency, the resonance frequency and the capacitor-current-feedback factor. Several suitable approaches are then proposed to improve the performance with the capacitor-current-feedback AD. The experimental results verify the presented research.
Porous Copper With Capillary Performance and Gas Permeability Prepared by Two-Step Foaming Method
Jinming Ru,Bo Kong,Tongxiang Fan,Di Zhang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
Porous copper have been prepared by two-step foaming method using 18%-72 wt% of C18H36O2 for the first-step foaming and 1.5 wt% of C7H10N2O2S for the second-step foaming. The effects of C18H36O2 contents and sintering time on pore structure, capillary performance and gas permeability were studied. The results show that porosity, pumping rate and gas permeability increase with the increase of C18H36O2 contents but decrease with the increase of sintering time. Porous copper with high pumping rate and gas permeability has potential as the support for mass and heat transfer in heat pipe.
Jinming Xu,Shaojun Xie,Binfeng Zhang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
For grid-connected LCL-filtered inverters, the inverter-side current can be used as the control object with one current sensor for both LCL resonance damping and over-current protection, while the grid-voltage feedforward or harmonic resonant compensator is used for suppressing low-order grid current harmonics. However, it was found that the grid current harmonics were high and often beyond the standard limitations with this control. The limitations of the inverter-side current control in suppressing low-order grid current harmonics are analyzed through inverter output impedance modeling. No matter which compensator is used, the maximum magnitudes of the inverter output impedance at lower frequencies are closely related to the LCL parameters and are decreased by increasing the control delay. Then, to improve the grid current quality without complicating the control or design, this study proposes designing the filter capacitance considering the current harmonic constraint and using a PWM mode with a short control delay. Test results have confirmed the limitation and verified the performance of the improved approaches.