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The successful commercialization of wireless power transfer (WPT) technology in mobile phones, laptops, and electric vehicles (EV), requires a safe, reliable, and efficient charging infrastructure. A metal object, such as a coin, a key, or a nail, however, may be inadvertently exposed, by close proximity, to the magnetic fields generated by the WPT coupler, creating a potential safety hazard and affecting the electrical characteristics of the WPT system. In addition, the magnetic fields may produce adverse symptoms, such as dizziness and breathlessness, in living objects near the charging systems. This paper provides a current state of the art review of all available designs for detecting metal and living objects in WPT systems. Working principles and qualitative comparisons in terms of sensitivity, accuracy, and cost of major detection methods are presented to reveal their inherent limitations and available applications. Finally, a number of research topics on foreign object detection (FOD) are suggested to encourage more researchers to make contributions to the development and commercial application of wireless charging systems.
Jianghua Lu; Guorong Zhu; Chunting Chris Mi. Foreign object detection in wireless power transfer systems. IEEE Transactions on Industry Applications 2021, PP, 1 -1.
AMA StyleJianghua Lu, Guorong Zhu, Chunting Chris Mi. Foreign object detection in wireless power transfer systems. IEEE Transactions on Industry Applications. 2021; PP (99):1-1.
Chicago/Turabian StyleJianghua Lu; Guorong Zhu; Chunting Chris Mi. 2021. "Foreign object detection in wireless power transfer systems." IEEE Transactions on Industry Applications PP, no. 99: 1-1.
The DC-link voltage control (DVC) timescale (i.e., the frequency dynamics covering converter outer controls) instabilities in wind generation have gained increased attention recently. This paper presents DVC timescale modeling and stability analysis for multi doubly-fed induction generators (DFIGs) connected to weak AC grids. A reduced-order, small-signal model of a grid-tied multi-DFIG system, designed for DVC dynamics analysis, is firstly proposed. The model allows for the dynamic interactions among the DC-link voltage control, active power control (APC), terminal voltage control (TVC) and phase-locked loop (PLL). Eigenvalue and participation factor analyses are conducted to explore the potential instabilities and correlated critical factors for such a multi-machine system. The sensitivity studies find that instability can occur at high levels of power generations or low short-circuit ratio (SCR) conditions. In addition, the dominant mode is identified to be highly related to the PLL, and its modal damping is decreased when the bandwidths of PLLs in different generators are close. Detailed model-based time domain simulations verified the analysis above.
Dong Wang; Houquan Chen; Yunhui Huang; Xiangtian Deng; Guorong Zhu. Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale. Energies 2020, 13, 3689 .
AMA StyleDong Wang, Houquan Chen, Yunhui Huang, Xiangtian Deng, Guorong Zhu. Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale. Energies. 2020; 13 (14):3689.
Chicago/Turabian StyleDong Wang; Houquan Chen; Yunhui Huang; Xiangtian Deng; Guorong Zhu. 2020. "Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale." Energies 13, no. 14: 3689.
Recent works have shown that phase-locked loop (PLL) synchronized wind turbines (WTs) suffer stability issues when integrated into weak grids. However, most of the current studies are limited to a single machine case, the interactions among the WTs are usually overlooked. This paper studies the stability of multiple doubly-fed induction generators (DFIGs) that are connected in parallel to a weak AC grid. A state space model of a two-DFIG system is firstly presented. Subsequently, eigenvalue sensitivity analysis shows that instability can occur at low short-circuit ratio (SCR) or heavy loading conditions. Meanwhile, participation factor analysis implies that the unstable mode is primarily induced by the interactions between the PLLs of the two WTs. Further, to make out how the PLLs interact to cause instability, a reduced-order model is proposed for analysis simplicity, and an explanation in terms of transfer function residue is given for illustration. Detailed model-based time domain simulations are conducted to validate the analyses’ results.
Dong Wang; Yunhui Huang; Min Liao; Guorong Zhu; Xiangtian Deng. Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids. Energies 2019, 12, 4361 .
AMA StyleDong Wang, Yunhui Huang, Min Liao, Guorong Zhu, Xiangtian Deng. Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids. Energies. 2019; 12 (22):4361.
Chicago/Turabian StyleDong Wang; Yunhui Huang; Min Liao; Guorong Zhu; Xiangtian Deng. 2019. "Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids." Energies 12, no. 22: 4361.
A parallel active power filter (APF) is generally used to suppress dynamic harmonic current and compensate reactive power in the grid. However, parallel APF may have a negative effect on the load current when compensating the nonlinear load of a voltage source type, which may lead to the amplification effect of the load harmonic current. In this paper, the fundamental causes of harmonic current amplification were analyzed by studying the harmonic current amplification effect when a parallel APF compensates a nonlinear load. According to the results of the theoretical derivation, a feasible method to limit this current amplification effect by changing the system structure and the APF’s own control was proposed, and the corresponding design scheme is given. Finally, the correctness of the theoretical derivation of the harmonic current amplification effect and the feasibility of the proposed solution were proven through simulation and experiment.
Xueliang Wei; Cunzhong Li; Mingxuan Qi; Bingyang Luo; Xiangtian Deng; Guorong Zhu. Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load. Energies 2019, 12, 3070 .
AMA StyleXueliang Wei, Cunzhong Li, Mingxuan Qi, Bingyang Luo, Xiangtian Deng, Guorong Zhu. Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load. Energies. 2019; 12 (16):3070.
Chicago/Turabian StyleXueliang Wei; Cunzhong Li; Mingxuan Qi; Bingyang Luo; Xiangtian Deng; Guorong Zhu. 2019. "Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load." Energies 12, no. 16: 3070.
This paper proposes an inductive power transfer (IPT) system with three-bridge switching compensation topology. With the proposed IPT topology, the equivalent circuit and the resonant condition are analyzed to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs. On this basis, multiple power levels can be achieved under CC/CV conditions by bridge arm switching, which makes it possible to complete charging tasks for multiple power level electric vehicles (EV) without switching the IPT system. A circuit simulation was built to verify the different power level switching effects of the structure. A 3.3 kW IPT system was designed to verify the proposed structure. At the rated output power, the experimental efficiency was up to 92.04% and 91.21% in CC and CV output modes, respectively.
Bingyang Luo; Yatao Shou; Jianghua Lu; Ming Li; Xiangtian Deng; Guorong Zhu; Luo; Shou; Lu; Li; Deng; Zhu. A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode. Electronics 2019, 8, 884 .
AMA StyleBingyang Luo, Yatao Shou, Jianghua Lu, Ming Li, Xiangtian Deng, Guorong Zhu, Luo, Shou, Lu, Li, Deng, Zhu. A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode. Electronics. 2019; 8 (8):884.
Chicago/Turabian StyleBingyang Luo; Yatao Shou; Jianghua Lu; Ming Li; Xiangtian Deng; Guorong Zhu; Luo; Shou; Lu; Li; Deng; Zhu. 2019. "A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode." Electronics 8, no. 8: 884.
Based on the operation characteristics of each dispatch unit, a multi-objective hierarchical Microgrid (MG) economic dispatch strategy with load level, source-load level, and source-grid-load level is proposed in this paper. The objective functions considered are to minimize each dispatching unit’s comprehensive operating cost (COC), reduce the power fluctuation between the MG and the main grid connect line, and decrease the remaining net load of the MG after dispatch by way of energy storage (ES) and clean energy. Firstly, the load level takes electric vehicles (EVs) as a means of controlling load to regulate the MG’s load fluctuation using its energy storage characteristics under time-of-use (TOU) price. Then, in order to minimize the remaining net load of the MG and the COC of the ES unit through Multiobjective Particle Swarm Optimization (MPSO), the source-load level adopts clean energy and ES units to absorb the optimized load from the load level. Finally, the remaining net load is absorbed by the main grid and diesel engines (DE), and the remaining clean energy is sold to the main grid to gain benefits at the source-grid-load level. Ultimately, the proposed strategy is simulated and analyzed with a specific example and compared with the EVs’ disorderly charging operation and MG isolated grid operation, which verifies the strategy’s scientificity and effectiveness.
Hui Hou; Mengya Xue; Yan Xu; Jinrui Tang; Guorong Zhu; Peng Liu; Tao Xu. Multiobjective Joint Economic Dispatching of a Microgrid with Multiple Distributed Generation. Energies 2018, 11, 3264 .
AMA StyleHui Hou, Mengya Xue, Yan Xu, Jinrui Tang, Guorong Zhu, Peng Liu, Tao Xu. Multiobjective Joint Economic Dispatching of a Microgrid with Multiple Distributed Generation. Energies. 2018; 11 (12):3264.
Chicago/Turabian StyleHui Hou; Mengya Xue; Yan Xu; Jinrui Tang; Guorong Zhu; Peng Liu; Tao Xu. 2018. "Multiobjective Joint Economic Dispatching of a Microgrid with Multiple Distributed Generation." Energies 11, no. 12: 3264.
The static VAR generator (SVG) is an important device in flexible AC transmission systems (FACTS) for the development of smart grids. Based on the basis principle of SVG and instantaneous reactive power theory, the conventional ip–iq and dq methods have a certain error when the three phase voltages are unbalanced. In this paper, the current detection algorithm is improved in cases of three-phase power asymmetry by using the fundamental positive-sequence reactive current instead of the voltage as the input of phase locked loop (PLL). So the problems caused by unbalanced three-phase voltages could be avoided. In addition, a moving average filter is designed to improve the performance of the detection accuracy and dynamic response. Experiments verify the correctness and effectiveness of the proposed scheme.
Xueliang Wei; Guorong Zhu; Jianghua Lu; Wenjing Li; And Erjie Qi; Erjie Qi. Improved Reactive Current Detection Method of SVG. Energies 2017, 10, 1374 .
AMA StyleXueliang Wei, Guorong Zhu, Jianghua Lu, Wenjing Li, And Erjie Qi, Erjie Qi. Improved Reactive Current Detection Method of SVG. Energies. 2017; 10 (9):1374.
Chicago/Turabian StyleXueliang Wei; Guorong Zhu; Jianghua Lu; Wenjing Li; And Erjie Qi; Erjie Qi. 2017. "Improved Reactive Current Detection Method of SVG." Energies 10, no. 9: 1374.
This study investigates design and analysis of direct current (DC)-link voltage stabiliser for voltage source converter (VSC) as connected to weak grid. To begin with, stability mechanism of VSC is investigated with integrated to weak grid. It is found that phase-locked loop and terminal voltage control perform as a lagging regulation for DC-link voltage control, decreasing stability of system. According the mechanism, DC-link voltage stabiliser needs to provide a leading regulation to eliminate the negative effects. Then, scheme, design and effect of DC-link voltage stabiliser are studied. Design schemes of stabiliser's inner control loops are presented by bode plots and control blocks. Moreover, control parameters of stabiliser are designed with some practical scenario. Furthermore, effects of stabiliser on VSC control system stability are investigated with varied grid strengths and operating points. Analysis results show that DC-link voltage stabiliser strengthens system damping and improve stability limits. Time-domain simulation results show DC-link voltage stability is improved with stabiliser integrated to VSC, verifying effectiveness of design schemes.
Yunhui Huang; Jinrui Tang; Guorong Zhu; Xianqiang Li; Haiyan Tang; Yan Li. Research on DC‐link voltage stabiliser for voltage source converter as connected to weak grid. The Journal of Engineering 2017, 2017, 2168 -2172.
AMA StyleYunhui Huang, Jinrui Tang, Guorong Zhu, Xianqiang Li, Haiyan Tang, Yan Li. Research on DC‐link voltage stabiliser for voltage source converter as connected to weak grid. The Journal of Engineering. 2017; 2017 (13):2168-2172.
Chicago/Turabian StyleYunhui Huang; Jinrui Tang; Guorong Zhu; Xianqiang Li; Haiyan Tang; Yan Li. 2017. "Research on DC‐link voltage stabiliser for voltage source converter as connected to weak grid." The Journal of Engineering 2017, no. 13: 2168-2172.
The Li-ion battery is becoming the optimal choice for the Electric Vehicle’s (EV) power supply. In order to protect the Li-ion battery from charging damage and to prolong the battery’s life, a special control strategy based on the dynamic balanced point along with a non-dissipative equalizer is presented. The main focus of the proposed control strategy is to insure that the individual cell of a battery pack will be rapidly, efficiently and simultaneously balanced, by adjusting equalizing current of each cell dynamically. In this paper, a model of a four series connected Li-ion batteries pack has been established to evaluate the proposed control strategy. Superior performance is demonstrated by the simulation and experiment.
Dong-Hua Zhang; Guo-Rong Zhu; Shao-Jia He; Shi Qiu; Yan Ma; Qin-Mu Wu; Wei Chen. Balancing Control Strategy for Li-Ion Batteries String Based on Dynamic Balanced Point. Energies 2015, 8, 1830 -1847.
AMA StyleDong-Hua Zhang, Guo-Rong Zhu, Shao-Jia He, Shi Qiu, Yan Ma, Qin-Mu Wu, Wei Chen. Balancing Control Strategy for Li-Ion Batteries String Based on Dynamic Balanced Point. Energies. 2015; 8 (3):1830-1847.
Chicago/Turabian StyleDong-Hua Zhang; Guo-Rong Zhu; Shao-Jia He; Shi Qiu; Yan Ma; Qin-Mu Wu; Wei Chen. 2015. "Balancing Control Strategy for Li-Ion Batteries String Based on Dynamic Balanced Point." Energies 8, no. 3: 1830-1847.