A Unified Grid Current Control for Grid-Interactive DG Inverters in Microgrids

Xiongfei Wang,Poh Chiang Loh,Frede Blaabjerg 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a unified grid current control for grid-interactive distributed generation inverters. In the approach, the grid-side current, instead of inverterside current, is controlled as an inner loop, while the filter capacitor voltage is indirectly regulated through a virtual admittance in the outer loop. It, therefore, provides several superior features over traditional control schemes: 1) highquality grid current in the grid-connected mode, 2) inherent derivative-less virtual output impedance control, and 3) the unified active damping for both grid-connected and islanded operations. Root locus analyses in the discrete z-domain are performed for elaborating the controller design. Simulations and experimental results demonstrate the performances of the proposed approach.

A Review of Power Electronics Based Microgrids

Wang, Xiongfei,Guerrero, Josep M.,Blaabjerg, Frede,Chen, Zhe The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

The increased penetration of Distributed Energy Resources (DER) is challenging the entire architecture of conventional electrical power system. Microgrid paradigm, featuring higher flexibility and reliability, becomes an attractive candidate for the future power grid. In this paper, an overview of microgrid configurations is given. Then, possible structure options and control methods of DER units are presented, which is followed by the descriptions of system controls and power management strategies for AC microgrids. Finally, future trends of microgrids are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible power system.

A Review of Power Electronics Based Microgrids

Xiongfei Wang,Josep M. Guerrero,Frede Blaabjerg,Zhe Chen 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

The increased penetration of Distributed Energy Resources (DER) is challenging the entire architecture of conventional electrical power system. Microgrid paradigm, featuring higher flexibility and reliability, becomes an attractive candidate for the future power grid. In this paper, an overview of microgrid configurations is given. Then, possible structure options and control methods of DER units are presented, which is followed by the descriptions of system controls and power management strategies for AC microgrids. Finally, future trends of microgrids are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible power system.

Precise Inductor Current Ripple Distribution of Three-Level Active Neutral-Point-Clamped Inverter

Donghua Pan,Mengxing Chen,Xiongfei Wang,Huai Wang,Frede Blaabjerg,Wei Wang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In power electronic converters, the inductor current ripple affects the system power loss and should be minimized. This paper studies in detail the output filter inductor current ripple distribution of a three-level active neutral-point-clamped (3L-ANPC) inverter. The peak-topeak current ripple per line cycle is precisely derived according to the modulation index. Then, the maximum current ripple is identified, and the concept of average current ripple is proposed to quantify the overall ripple level. An optimal operating point with minimum ripple level is found, and it is chosen as the nominal operation condition of the 3L-ANPC inverter. Simulations are performed in a case study to confirm the theoretical expectations.

EMI Modeling of Three-Level Active Neutral-Point-Clamped SiC Inverter Under Different Modulation Schemes

Donghua Pan,Mengxing Chen,Xiongfei Wang,Huai Wang,Frede Blaabjerg,Wei Wang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper investigates the electromagnetic interference (EMI) emission in three-level active neutralpoint-clamped (3L-ANPC) silicon carbide (SiC) inverter. Four typical modulation schemes of 3L-ANPC inverter are considered. An EMI model is established by including all the system parasitics and noise sources. Based on this model, a comparison of different modulation schemes on EMI emission is carried out. Simulations are performed in a case study to confirm the theoretical expectations.

Switching Characterization of SiC MOSFETs in Three-Level Active Neutral-Point-Clamped Inverter Application

Mengxing Chen,Donghua Pan,Huai Wang,Xiongfei Wang,Frede Blaabjerg,Wei Wang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The switching characterization of power devices is critical for improving the efficiency and reliability of power electronic converters. In this paper, the switching characteristics of silicon carbide (SiC) MOSFETs in a three-level active neutral-point-clamped (3L-ANPC) inverter are investigated. A parasitic model of the 3L-ANPC phase-leg is proposed first based on a design case and its ANSYS/Q3D simulation. Then, two typical commutation modes for ANPC inverters, namely the outer mode and the inner mode, are studied, and the separate switching loops and parasitic inductances are identified according to the parasitic model. Knowing this, double-pulse tests (DPTs) for each type of commutation are conducted. The differences in terms of switching characteristics and switching dissipations are fully revealed. The conclusion drawn can be utilized for developing the next-generation highly efficient and reliable SiC MOSFET based 3L-ANPC inverters.

Precise Model Analysis for 3-phase High Power Converter using the Harmonic State Space Modeling

JunBum Kwon,Xiongfei Wang,Frede Blaabjerg,Claus Leth Bak 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper presents about the generalized multi-frequency modeling and analysis methodology, which can be used in control loop design and stability analysis. In terms of the switching frequency of high power converter, there can be harmonics interruption if the voltage source converter has a low switching frequency ratio or multisampling frequency. The range of the control bandwidth can include the switching component. Thus, the systems become unstable. This paper applies the Harmonic State Space (HSS) Modeling method in order to find out the transfer function for each harmonics terms. The modeling procedure shows the precision in the analysis of the stability as well as the controller design. The overall results are validated by using not only the non-linear time domain simulation, but also the analytical model.

Experimental Study on Reinforcement and Chloride Extraction of Concrete Column with MPC-CFRP Composite Anode

Yue Li,Xiongfei Liu,Zigeng Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4

In this research, Magnesium Phosphate Cement (MPC) was innovatively used to bond with Carbon Fiber Reinforced Plastic (CFRP) in order to form the MPC-CFRP as a composite material, adopted both for chloride ions extraction and reinforcement of concrete columns. First of all, a series of tests were conducted to evaluate the feasibility of the MPC-CFRP as anode of Electrochemical Chloride Extraction (ECE) system, including chloride ions concentration, Scanning Electron Microscope (SEM) and tensile strength. Then, the MPC-CFRP was used to wrap around reinforced concrete column for the sake of reinforcement and extraction of chloride ions. The test results indicated that the chloride extraction efficiency and the tensile resistance of the MPCCFRP electrode were superior to the control group. The ECE process can decrease the interface bonding strength between the concrete and the steel rebar while the compression resistance of the columns could be increased remarkably. Therefore, the MPCCFRP composite material is capable of achieving the dual functions of strengthening and repairing the reinforced concrete construction.

Benchmarking of Small-signal Dynamics of single-phase PLLs

Chong Zhang,Xiongfei Wang,Frede Blaabjerg,Weisheng Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Phase-looked Loop (PLL) is a critical component for the control and grid synchronization of grid-connected power converters. This paper presents a benchmarking study on the small-signal dynamics of three commonly used PLLs for single-phase converters, including enhanced PLL, second-order generalized integrator based PLL, and the inverse-PLL. First, a unified small-signal model of those PLLs is established for comparing their dynamics. Then, a systematic design guideline for parameters tuning of the PLLs is formulated. To confirm the validity of theoretical analysis, nonlinear time-domain simulation results and experimental results are presented.

Recoil reduction and projectile velocity improvement design of recoilless gun with combustible cartridge

Pengzhan Liu,Guoqiang Wang,Zhen Yang,Xiongfei Zhao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

In the era of unmanned war, with the increasing muzzle velocity requirement, the design of gun is significantly restricted by recoil, especially for guns installed on unmanned aerial vehicles. A recoilless gun with combustible cartridge was designed to eliminate recoil and increase projectile velocity, and the influence of main parameters on recoil was studied. First, a design of a recoilless gun with high projectile velocity is proposed based on combustible cartridge case. Next, a classical interior ballistic model is developed during the recoilless gun firing cycle, and the effect of main parameters of interior ballistics on the performance is investigated. Additionally, simple nonlinear fitting formulae are defined to highlight the variation of recoil momentum with the time of interior ballistic model. Finally, numerical simulation results are compared with the test results to validate the feasibility of the design. The experimental results demonstrate that the classical interior ballistic model can be used to accurately analyze the effect of the parameters on the projectile velocity and the recoil reduction efficiency. The projectile velocity of the recoilless gun could raised to 1200 m/s and the recoil momentum could be eliminated almostly. Therefore, the newly designed recoilless gun effectively eliminates the recoil momentum and significantly improves the projectile velocity. The findings should make an important contribution to the field of engineering applications of recoilless gun.