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该文提出了一种多端口直流–直流自耦变压器的拓扑，该多端口直流自耦变压器用于互联多个直流电压等级不同的直流系统。提出了多端口直流自耦变压器的潮流直接分析法以及潮流分解分析法，推导了多端口直流自耦变压器中各换流器额定电压与额定功率设计方法，设计了多端口直流自耦变压器的控制策略。以一个三端口直流自耦变压器为测试算例，在PSCAD/EMTDC下仿真验证了多端口直流自耦变压器的技术可行性。以互联±250、±320 kV和±400 kV直流系统为例，假设±250 kV 和±320 kV 系统的额定输入/输出功率分别为500 MW和1000 MW，采用常规的多端口直流–直流变换器技术所需要的换流器总容量为3000 MW，而采用多端口直流自耦变压器技术所需要总的换流器仅为775 MW，所使用的换流器总容量仅为现有技术的26%，显著节省了成本，降低了运行损耗。“,”This paper proposed a multiport DC-DC autotransformer to interconnect multiple DC grids with different DC voltages. Decomposed power flow analysis and direct power flow analysis for the multiport DC auto were proposed. Methods of dimensioning the voltage and power rating of each of the VSC converters in the multiport DC auto were derived. Controllers were designed to keep stable operation of the multiport DC auto. Simulation results of a 3-port DC auto demonstrated the technical feasibility of the multiport DC-DC autotransformer. Taking a 3-port DC auto interconnecting ±250, ±320 and ±400 kV DC grids as an example, suppose the power rating for each of the port is 500, 1 000 and 1 500 MW respectively, the 3-port DC auto only needs 775 MW VSC converters while a total of 3 000 MW VSC converters is required for conventional technology. The multiport DC auto can save significant amount of investment compared with conventional DC-DC technology.