基于阻抗源变换器的光伏直流升压汇集系统

针对大型光伏电站直流升压汇集技术挑战,提出一种计及阻抗网络概念的新型光伏直流升压汇集系统解决方案。该方案以一种阻抗型多模块串联式直流升压变换器为核心,具备多路最大功率点跟踪(MPPT)与高增益升压变流一体化功能,从而无需低压直流母线与专用MPPT装置,结构清晰可靠,便于内部故障隔离与整站动态控制。阻抗网络的引入,一方面具备灵活调压能力,可有效地解决输入光伏阵列间功率不均衡问题,具备良好运行适应性;另一方面具备抵御直通短路故障能力,可以大幅度提升电力电子系统运行可靠性。详述了系统架构、核心直流升压变流器拓扑、工作原理与控制方法。针对光伏阵列输出功率均衡与不均衡两种典型工况,对该系统进行仿真验证。仿真结果表明所述理论分析正确可靠,该系统对于未来直流光伏电站的推广应用具备潜在应用价值。

Impedance-source Converter Based Direct Current Step-up Collection System for Photovoltaic

A novel structure of direct current(DC)step-up collection system for photovoltaic(PV)with consideration of impedance network concept has been proposed to cope with technical challenges to large-scale PV station. An impedance-source multi-module cascaded DC-DC step-up converter serves as the key device for the proposed collection system, which has an integrated function of multi-channel maximum power point tracking(MPPT)control and high-gain DC step-up conversion. The low-voltage DC bus and distributed MPPT devices can be forgone to make the system simple and reliable. The system structure is beneficial to internal fault isolation and unitary dynamic control at station level. The introduction of impedance network makes it possible to adjust the voltage gain flexibly as well as resist shoot-through of bridge arms, which can improve the operational adaptability against input power mismatch and reliability of the DC step-up collection system for PV. A detailed introduction of system architecture, key DC step-up converter, working principle and control/modulation strategy has been given. All theoretical results have been validated by system simulation under balanced and mismatched power inputs. The proposed DC step-up collection system has a potential application value in the future construction of large-scale PV stations.