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In order to supply the single-phase locomotive load and mitigate the negative sequence current, this paper develops a V/V transformer-based connection and control strategy of three-phase photovoltaic (PV) converters integrated into railway traction power supply systems. In this V/V transformer-based connection, the two-phase traction voltage is converted into the three-phase voltage. This approach can offer a common low voltage AC bus, which is more convenient for more access to three-phase PV converters. Based on this V/V transformer-based connection, an individual phase current control strategy with the hybrid current reference is fully designed. In this control strategy, the current reference, containing two parts, is generated. One is the asymmetrical part for powering the single-phase locomotive load and mitigating the negative sequence current. The other is the symmetrical part for feeding the surplus power back to the utility grid. Then, each phase current replaces the dual-sequence current to be controlled to track the corresponding phase current reference. Consequently, PV converters can flexibly inject the symmetrical and asymmetrical currents without the dual-sequence extraction for a simpler implementation. Finally, the effectiveness of the developed connection and control strategy is validated by the simulation studies.
Peng Cheng; Chao Wu; Huiwen Kong; Frede Blaabjerg; Yu Quan. Connection and Control Strategy of PV Converter Integrated into Railway Traction Power Supply System. Energies 2020, 13, 5989 .
AMA StylePeng Cheng, Chao Wu, Huiwen Kong, Frede Blaabjerg, Yu Quan. Connection and Control Strategy of PV Converter Integrated into Railway Traction Power Supply System. Energies. 2020; 13 (22):5989.
Chicago/Turabian StylePeng Cheng; Chao Wu; Huiwen Kong; Frede Blaabjerg; Yu Quan. 2020. "Connection and Control Strategy of PV Converter Integrated into Railway Traction Power Supply System." Energies 13, no. 22: 5989.
The system performances can be potentially enhanced for three-phase inverter parallel operation in droop-controlled AC microgrid by using network-based control, which also benefits for the extension of other control strategies in microgrids (MGs). It is highlighted that some negative factors such as network-induced time-delays and data dropouts would possibly degrade the system operation. In this paper, the comprehensive analysis of network-based control strategy with strong robustness and wide time-scale compatibility is investigated in islanded mode of an AC microgrid with paralleled inverters. The theoretical evaluation towards time-delay and data dropouts is made and it is verified that its good power-sharing can be obtained under unsatisfactory communication conditions. It has been observed that the time-scale of network-based control can also be designed from several microseconds to milliseconds. Based on this idea, the communication integration of different layers of MGs in hierarchical structure would be realistic. Experimental results have verified the effectiveness of the network-based control strategy and analytical method.
Yao Zhang; Fan Zhang; Yu Quan; Pengfei Zhang. Analysis of Three-Phase Inverter Parallel Operation with Network-Based Control Having Strong Robustness and Wide Time-Scale Compatibility in Droop-Controlled AC Microgrid. Electronics 2020, 9, 376 .
AMA StyleYao Zhang, Fan Zhang, Yu Quan, Pengfei Zhang. Analysis of Three-Phase Inverter Parallel Operation with Network-Based Control Having Strong Robustness and Wide Time-Scale Compatibility in Droop-Controlled AC Microgrid. Electronics. 2020; 9 (2):376.
Chicago/Turabian StyleYao Zhang; Fan Zhang; Yu Quan; Pengfei Zhang. 2020. "Analysis of Three-Phase Inverter Parallel Operation with Network-Based Control Having Strong Robustness and Wide Time-Scale Compatibility in Droop-Controlled AC Microgrid." Electronics 9, no. 2: 376.
In general, the integral sliding mode control (ISMC) with an integral sliding surface would lead to tracking errors under unbalanced and harmonic grid voltage conditions. In order to eliminate tracking errors under these conditions, multi-resonant items are added to the conventional integral sliding surface in the proposed strategy, which can be called multi-resonant-based sliding mode control (MRSMC). A comparison of tracking precision on the ISMC and MRSMC is analyzed. In order to regulate the system powers directly, the errors of instantaneous active and reactive powers are selected as the state variables. Finally, the output current harmonics and a majority of the doubly-fed induction generator’s (DFIG) electromagnetic torque pulsations can be removed under unbalanced and harmonic grid voltage conditions. Simulation and experimental results are presented to verify the correctness and effectiveness of the proposed strategy.
Yu Quan; Lijun Hang; Yuanbin He; Yao Zhang. Multi-Resonant-Based Sliding Mode Control of DFIG-Based Wind System under Unbalanced and Harmonic Network Conditions. Applied Sciences 2019, 9, 1124 .
AMA StyleYu Quan, Lijun Hang, Yuanbin He, Yao Zhang. Multi-Resonant-Based Sliding Mode Control of DFIG-Based Wind System under Unbalanced and Harmonic Network Conditions. Applied Sciences. 2019; 9 (6):1124.
Chicago/Turabian StyleYu Quan; Lijun Hang; Yuanbin He; Yao Zhang. 2019. "Multi-Resonant-Based Sliding Mode Control of DFIG-Based Wind System under Unbalanced and Harmonic Network Conditions." Applied Sciences 9, no. 6: 1124.