The new characteristics and phenomena of hybrid AC/DC transmission grids challenge the conventional protection concepts. In hybrid AC/DC overhead line systems, AC and DC systems are located on the same support structure. As a result, electromagnetic and galvanic interactions between the AC- and the DC-line influence the AC-protection and the DC-control in a novel and complex way. This paper presents key findings and solutions from a current 400-kV-hybrid AC/DC overhead line project in Germany. The focus is on AC/DC intersystem faults, i.e. galvanic contact between DC and AC systems. Fault detection and fault response of the AC-protection and the DC-control as well as a proper AC/DC protection coordination are discussed. The paper illustrates the challenges of a secure and dependable fault clearing and indicates solution methods. The findings of this paper are based on EMT simulations with detailed PSCAD-models of the hybrid AC/DC overhead line and the VSC-converters. Laboratory protection tests have been conducted and confirmed the results.

中文翻译：

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混合输电电网中交直流系统间故障的保护协调


交直流混合输电电网的新特点和新现象对传统保护理念提出了挑战。在交直流混合架空线路系统中，交流和直流系统位于同一支撑结构上。因此，交流和直流线路之间的电磁和电流相互作用以一种新颖且复杂的方式影响交流保护和直流控制。本文介绍了德国当前 400 kV 混合交流/直流架空线路项目的主要发现和解决方案。重点是交流/直流系统间故障，即直流和交流系统之间的电流接触。讨论了交流保护和直流控制的故障检测和故障响应以及适当的交流/直流保护协调。本文阐述了安全可靠的故障清除所面临的挑战，并指出了解决方法。本文的研究结果基于 EMT 仿真以及混合交流/直流架空线路和 VSC 转换器的详细 PSCAD 模型。已进行实验室防护测试并确认结果。