一种基于CSC-VSC的DC/DC换流器及其控制策略

在能源互联网建设中，DC/DC换流器是实现不同直流电压等级的可再生能源并网的必要环节，引起了广泛的研究。DC/DC换流器的体积、成本、动稳态性能和故障性能是其广泛应用的限制因素。为此，提出了一种并网端采用有源电流源换流器、分布式能源端采用电压源换流器的front-to-front混合DC/DC换流器，其中CSC和VSC交流侧采用高频率正弦波调制。所提出的基于CSC-VSC的混合DC/DC换流器具有体积小、成本低、可穿越直流短路故障等优点。通过对混合DC/DC换流器数学模型的分析，提出了换流器参数设计方法，给出了换流器运行范围约束。再提出了一种适用于混合DC/DC换流器的综合控制策略，其中CSC采用有功无功闭环控制、VSC采用交流电压幅值闭环控制。利用RTLAB半实物仿真平台分别对混合DC/DC换流器额定运行工况和直流短路工况进行了实验研究，结果验证了所提混合DC/DC换流器拓扑和控制策略的合理性和有效性。

CSC-VSC Based DC/DC Converter and Its Control Strategy

In the construction of energy internet, the DC/DC converter is a necessary link to realize the grid connection of renewable energy at different DC voltage levels, which has attracted extensive attention. Its volume, cost, dynamic and steady-state performances and fault performance have gradually become constraints for its wide applications. Under this background, a front-to-front hybrid DC/DC converter is proposed in this paper, with an active current source converter(CSC) on the grid side and a voltage source converter(VSC) on the distributed energy side. The AC side of CSC and VSC adopts a high-frequency sine wave modulation. The proposed CSC-VSC based hybrid DC/DC converter has advantages such as small volume, low cost and DC short-circuit fault ride through capability. Through the analysis of the mathematical model of the hybrid DC/DC converter, its parameter design method is put forward, and its operation range constraints are also derived. An integrated control strategy for the hybrid DC/DC converter is proposed, in which CSC adopts active and reactive closed-loop control and VSC adopts AC voltage amplitude closed-loop control. The rated operation condition and DC short-circuit circumstance of the hybrid DC/DC converter were experimentally studied by using a RTLAB hardware-in-the-loop simulation platform, and results verify the rationality and effectiveness of the proposed hybrid DC/DC converter topology and its control strategy.