直流自耦变压器样机设计与实验验证

Design and Experimental Verification of DC Autotransformer Prototype

当互联不同电压等级的直流输电系统时,需要利用直流变压器技术。直流自耦变压器凭借其结构特点,被认为是最具经济性的拓扑之一。文章研制了由两电平电压源型换流器组成的直流自耦变压器（DC AUTO）实验样机。通过将双向DC AUTO中特定的电压源换流器闭锁便可将其重构为单向直流自耦变压器。设计了实验样机系统主接线,研究了各VSC换流器单元在不同工作模式下的控制策略及其控制系统架构,提出一种应用于单向直流自耦变压器的带电流保护的双环控制器,详细分析了实验样机的启动方法及其功率传输特性。通过直流功率传输实验验证了不同类型的直流自耦变压器的可行性,实验结果表明,实验样机在稳态直流功率传输、潮流反转等工况下具有较好的静态和动态性能,系统功率响应迅速且跟踪准确。

To interconnect HVDC systems with different voltage levels,DC transformers are the most important devices.Among different topologies of DC transformers,DC autotransformer（DC AUTO） is one of the most promising technologies.This paper develops a DC-DC autotransformer prototype constructed with two-level voltage source converters（VSC）.By blocking specific VSC converter,a bidirectional DC AUTO can be reconfigured to a unidirectional DC AUTO.Main circuit configuration of an experimental prototype is designed.Control strategies and control system architecture of each VSC for different operation modes are presented.And a dual-loop controller with current protection is proposed.The startup method and operating characteristics are analyzed.Feasibility of different topologies for DC AUTO is verified in experimental conditions,such as DC power step and reversal.Experiment results show that the prototypes have excellent static and dynamic performance under DC power step and DC power flow reversal.