This paper presents a method for optimizing a grid-connected photovoltaic system through an LCL filter. An algorithm based on particle swarm optimization (PSO) is used to determine the number of batteries, the number ...This paper presents a method for optimizing a grid-connected photovoltaic system through an LCL filter. An algorithm based on particle swarm optimization (PSO) is used to determine the number of batteries, the number of panels in series and in parallel, as well as to evaluate the joule losses due to cable heating and the switching losses of the multilevel inverters. This system is applied to a village named YAGOUA, located in the far north of Cameroon. The evaluation of the Joule effect and the switching losses as well as the regulation of the voltage level at the point of common coupling (PCC) are carried out in PVsyst and Matlab software, then at IEEE 33 bus. This algorithm reduced the Joule losses to 1.2% and the switching losses to 2.2%. A power of 210.4 MWh is produced, to be injected in the electrical network via an LCL filter. The THD calculation gave a rate of 3.015% in accordance with the 519 standards. Synchronization through the Phase Locked Loop (PLL) is performed. After the power was injected into the grid, the voltage and current remained in phase, showing the power factor correction and the efficiency of the filter. According to NASA meteorological data, the locality of YAGOUA gives the global solar irradiation forecast of 6.8 kW/m2.展开更多
Grid-connected LCL-filtered inverters are commonly used for distributed power generators. The LCL resonance should be treated properly. Recently, many strategies have been used to damp the resonance, but the relations...Grid-connected LCL-filtered inverters are commonly used for distributed power generators. The LCL resonance should be treated properly. Recently, many strategies have been used to damp the resonance, but the relationships between different damping strategies have not been thoroughly investigated. Thus, this study analyses the essential mechanisms of LCL-resonance damping and reviews state-of-the-art resonance damping strategies.Existing resonance damping strategies are classified into those with single-state and multi-state feedback. Singlestate feedback strategies damp the LCL resonance using feedback of a voltage or current state at the resonance frequency. Multi-state feedback strategies are summarized as zero-placement and pole-placement strategies, where the zero-placement strategy configures the zeros of a novel state combined by multi-state feedback, while the poleplacement strategy aims to assign the closed-loop poles freely. Based on these mechanisms, an investigation of single-state and multi-state feedback is presented, including detailed comparisons of the existing strategies. Finally,some future research directions that can improve LCL-filtered inverter performance and minimize their implementation costs are summarized.展开更多
由于传统的插入式系统结构繁杂且频繁插拔容易发生电火花等危险,因此无线电能传输(wireless power transfer,WPT)系统凭借其固有的优势得到了广泛的研究,逐渐融入各种工业应用中.为了确保电池的性能及使用寿命,有效地为电池提供所需的...由于传统的插入式系统结构繁杂且频繁插拔容易发生电火花等危险,因此无线电能传输(wireless power transfer,WPT)系统凭借其固有的优势得到了广泛的研究,逐渐融入各种工业应用中.为了确保电池的性能及使用寿命,有效地为电池提供所需的恒定充电电流和恒定充电电压是非常必要的.然而在充电过程中,电池的等效电阻会发生显著变化从而导致系统很难在近似零相位角(zero phase angle,ZPA)运行下同时实现与负载无关的恒流输出和恒压输出.鉴于此,提出1种基于S/LCL补偿的WPT系统,该系统可以在2个固定频率下实现具有ZPA运行的恒流和恒压输出.最后,搭建了1台恒流充电为3 A和恒压充电为80 V的验证性实验样机,验证了所设计的WPT系统的正确性和可行性.展开更多
The design of reliable controllers for wind energy conversion systems(WECSs)requires a dynamic model and accurate parameters of the wind generator.In this paper,a dynamic model and the parameter measurement and contro...The design of reliable controllers for wind energy conversion systems(WECSs)requires a dynamic model and accurate parameters of the wind generator.In this paper,a dynamic model and the parameter measurement and control of a direct-drive variable-speed WECS with a permanent magnet synchronous generator(PMSG)are presented.An experimental method is developed for measuring the key parameters of the PMSG.The measured parameters are used in the design of the controllers.The generator-side converter is controlled using a vector control scheme that maximizes the power extraction under varying wind speeds.A model predictive controller(MPC)is designed for the grid-side voltage source converter(VSC)to regulate the active and reactive power flows to the power grid by controlling the d-and q-axis currents in the synchronous reference frame.The MPC predicts the future values of the control variables and takes control actions based on the minimum value of the cost functions.To comply with the grid code requirement,a modified design approach for an LCL filter is presented and incorporated into the system.The design process is simple and incorporates significant filter parameters while avoiding iterative calculations.The comparative analysis of the designed filter with conventional L,LC,and iterative LCL filters demonstrates the effectiveness of the modified design approach.The proposed wind energy system with MPC and LCL filter is simulated in MATLAB/Simulink and experimentally implemented in the laboratory using the dSpace digital signal processor(DSP)system.The simulation and experimental results validate the efficacy of the designed controllers using the measured parameters and show dynamic and steady-state performance under varying wind speeds.展开更多
文摘This paper presents a method for optimizing a grid-connected photovoltaic system through an LCL filter. An algorithm based on particle swarm optimization (PSO) is used to determine the number of batteries, the number of panels in series and in parallel, as well as to evaluate the joule losses due to cable heating and the switching losses of the multilevel inverters. This system is applied to a village named YAGOUA, located in the far north of Cameroon. The evaluation of the Joule effect and the switching losses as well as the regulation of the voltage level at the point of common coupling (PCC) are carried out in PVsyst and Matlab software, then at IEEE 33 bus. This algorithm reduced the Joule losses to 1.2% and the switching losses to 2.2%. A power of 210.4 MWh is produced, to be injected in the electrical network via an LCL filter. The THD calculation gave a rate of 3.015% in accordance with the 519 standards. Synchronization through the Phase Locked Loop (PLL) is performed. After the power was injected into the grid, the voltage and current remained in phase, showing the power factor correction and the efficiency of the filter. According to NASA meteorological data, the locality of YAGOUA gives the global solar irradiation forecast of 6.8 kW/m2.
基金supported by National Natural Science Foundation of China(No.51477077)
文摘Grid-connected LCL-filtered inverters are commonly used for distributed power generators. The LCL resonance should be treated properly. Recently, many strategies have been used to damp the resonance, but the relationships between different damping strategies have not been thoroughly investigated. Thus, this study analyses the essential mechanisms of LCL-resonance damping and reviews state-of-the-art resonance damping strategies.Existing resonance damping strategies are classified into those with single-state and multi-state feedback. Singlestate feedback strategies damp the LCL resonance using feedback of a voltage or current state at the resonance frequency. Multi-state feedback strategies are summarized as zero-placement and pole-placement strategies, where the zero-placement strategy configures the zeros of a novel state combined by multi-state feedback, while the poleplacement strategy aims to assign the closed-loop poles freely. Based on these mechanisms, an investigation of single-state and multi-state feedback is presented, including detailed comparisons of the existing strategies. Finally,some future research directions that can improve LCL-filtered inverter performance and minimize their implementation costs are summarized.
文摘The design of reliable controllers for wind energy conversion systems(WECSs)requires a dynamic model and accurate parameters of the wind generator.In this paper,a dynamic model and the parameter measurement and control of a direct-drive variable-speed WECS with a permanent magnet synchronous generator(PMSG)are presented.An experimental method is developed for measuring the key parameters of the PMSG.The measured parameters are used in the design of the controllers.The generator-side converter is controlled using a vector control scheme that maximizes the power extraction under varying wind speeds.A model predictive controller(MPC)is designed for the grid-side voltage source converter(VSC)to regulate the active and reactive power flows to the power grid by controlling the d-and q-axis currents in the synchronous reference frame.The MPC predicts the future values of the control variables and takes control actions based on the minimum value of the cost functions.To comply with the grid code requirement,a modified design approach for an LCL filter is presented and incorporated into the system.The design process is simple and incorporates significant filter parameters while avoiding iterative calculations.The comparative analysis of the designed filter with conventional L,LC,and iterative LCL filters demonstrates the effectiveness of the modified design approach.The proposed wind energy system with MPC and LCL filter is simulated in MATLAB/Simulink and experimentally implemented in the laboratory using the dSpace digital signal processor(DSP)system.The simulation and experimental results validate the efficacy of the designed controllers using the measured parameters and show dynamic and steady-state performance under varying wind speeds.
