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该文研究了一种单向直流–直流自耦变压器。该单向直流自耦变压器由电压源型换流器与不控整流器串联而成，包括升压型单向直流自耦变(UUDAT)和降压型单向直流自耦变(DUDAT)两类拓扑。提出UUDAT以及DUDAT的直流功率控制策略，分析了高压直流系统故障以及低压直流系统故障下，UUDAT和DUDAT的直流故障响应并提出相应的故障隔离措施，评估了直流故障隔离能力对 UUDAT 和DUDAT造价的影响。在PSCAD/EMTDC下通过对±320kV/±500kV,1000MW的UUDAT和DUDAT的仿真，验证了UUDAT和DUDAT的技术可行性。由于使用了自耦技术， UUDAT和DUDAT相比于常规的DC-AC-DC型单向DC/DC可以较大地节省所使用的电压源型换流器、不控整流器和交流链路的容量。“,”This article studied a type of unidirectional DC- DC autotransformers, which is composed by serial connection of voltage source converters and uncontrolled rectifiers. It includes two types of topologies, a step-up unidirectional DC AUTO (UUDAT) and a step-down unidirectional DC AUTO (DUDAT). A control strategy for UUDAT and DUDAT was proposed. DC fault responses during high and low voltage side DC faults were analyzed, and corresponding DC fault isolating mechanisms were designed. Impacts of DC fault isolating on converter costs of UUDAT and DUDAT were also studied. Simulations of a ±320kV/ ±500kV, 1000MW UUDAT and DUDAT on PSCAD/EMTDC verifies technical feasibility of UUDAT and DUDAT. Because of the employing DC-DC autotransformer technology, the UUDAT and DUDAT are able to significantly reduce the power ratings of converters and AC links compared with the traditional unidirectional DC/DC based on DC-AC-DC technologies.