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Wu Cao,Kangli Liu,Sheng Xu,Haotian Kang,Jianfeng Zhao 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3
The frequent starting of large capacity lifting machines and other surge ship electrical loads will result in severe impacts on a shipboard power network, such as voltage and frequency fl uctuations. Therefore, a novel stabilization control strategy for shore power systems based on virtual synchronous generator is proposed in this paper, so as to improve the power quality and enhance the stability and reliability of shipboard power networks. In this strategy, a reactive power inertia component is embedded into the virtual synchronous generator aiming at shipboard surge reactive powers. On this basis, a voltage and frequency stability control method is presented to improve the static performances of shore power systems. In addition, a d-q decoupling control scheme in synchronous reference frame for the voltage and current double closed-loop control system is designed, and moreover, the infl uence of diff erent feedback voltages on the output characteristics of shore power supplies is studied. The theoretical analysis, simulation and experiment results show that, the proposed control strategy can eff ectively attenuate the frequency and voltage fl uctuations, eliminate the frequency and voltage steady-state errors, as well as realize the power distribution evenly for modular shore power supplies.
Improved Switching Ripple Suppression Strategy for Multi-Paralleled Grid-Connected Inverters System
Wu Cao,Haotian Kang,Kangli Liu,Shunyu Wang,Jianfeng Zhao,Xiaochun Ji,Jun Zhao 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The switching operations of inverters in the distributed system inevitably introduce high-frequency harmonics into grid, which may make influences on electrical devices. To address it, this paper proposes a ripple suppression strategy based on active cancellation combined with passive filtering. The active cancellation is realized by carrier-phase-shift (CPS) technique and the passive filtering is achieved by filters. Furthermore, two component-shared LCL-type filters improved by traditional LCL filters are studied from the points of resonance and accuracy of gridinjected current. To valid the effectiveness of the proposed strategy, simulations and experimental test are carried out. The results show that the proposed strategy can effectively suppress high-frequency harmonics and two componentshared LCL-type filters can become promising filters for the multi-paralleled grid-connected inverters.