直流配电网多端口电力电子变压器拓扑与控制关键问题研究

直流配电网是高效接纳分布式电源、彻底治理配电网电能质量、可靠实现电网稳定经济运行的有效途径。直流配电网中，不同类型负荷的供电电压等级跨度较大，不同类型分布式电源输出电压等级也不同。包含多电压等级的直流配电网需要大量电能变换器，为了减少单一功能变换器的使用，解决多台变换器解耦与协调难题，提高电网运行效率，提出用一台多功能变换器替代多台单一功能变换器的思路。本项目拟研究直流多端口电力电子变压器DC-MPET，实现一台变换器解决多电压等级电压变换和潮流分配与转移难题。拟重点解决DC-MPET跨越多电压等级的高增益大功率多端口拓扑设计难题；揭示负荷与分布式电源波动下的DC-MPET运行机理，确定其电压稳定与潮流平衡策略；研究电网扰动下DC-MPET故障保护策略和容错运行方式。本项目为直流配电网和用户直流供电系统等领域的发展提供重要理论与技术支撑，应用前景广阔，具有重要的科学意义与研究价值。

DC distribution network is an effective way to incorporate distributed generation, improve the power quality of distribution network, and realize the stable operation of power grid. In DC distribution network, the voltage grade span of different load is large, and the output voltages DGs with different types are different. Therefore, there are many different voltage levels, and it needs large number of power converters. In order to avoid using single function converter, and solve the decoupling and coordination problem when lots of converters running together, a multifunctional converter is proposed to replace the single function converters. This project intends to study Direct Current Multi-port Power Electronic Transformer (DC-MPET), and implements one converter to solve the difficult problems of voltage transformation and power flow distribution under multi-voltage grades. This project intends to solve the topology design problems of DC-MPET when high-power, high-gain and multi-port is considered; It also reveals the operation mechanism of DC – MPET under the conditions of load and DG fluctuation, and proposes a control strategy to stabilize the voltage and to balance the power flow; It studies the fault protection strategies and fault-tolerant operation of DC-MPET with electrical disturbances. This project will provide theoretical and technical support for the development of DC distribution network. The application prospect is wide, and this project is with important scientific significance and research value.