柔性直流电网直流侧故障快速处理关键技术研究

柔性直流电网直流侧故障的快速处理是直流电网安全稳定与可靠运行的重要保障。针对柔性直流电网对保护和直流断路器的快速性要求，以及工程上面临的直流断路器高昂成本与无选择性重合闸问题，本项目开展直流线路故障处理的关键技术研究。主要内容包括：1)分析直流线路区内外故障时暂态电压与电流的频域/时域波形特征，研究基于单端量和双端量的柔直线路快速保护原理以及干扰信号的识别方法；2)对于单/双极不同故障类型，分析被开断的故障极线路上的耦合电压特征，构建瞬时性与永久性故障的识别判据；设计基于直流断路器的信号注入控制策略，分析信号在线路上的传播特征，研究柔直线路瞬时性故障与永久性故障的识别方法，制定自适应重合闸方案；3)研究多端口、多功能直流断路器的拓扑及其控制策略；4)基于上述理论成果，试制保护与新型直流断路器的实验样机。通过理论创新和样机试制，为柔性直流电网直流侧故障的快速处理提供技术支持。

The fast isolation of dc side fault occurring in the flexible DC grid is an important guarantee for the safe, steady and reliable operation of DC grid. Aiming at the requirement of fast operation speed of relay and DC circuit breaker in DC gird, and the questions of the DC CB giant capital and non-selective reclosure faced with by the DC engineering, the key technologies will be developed by this project. The main contents are as follows: 1) Analyzing the time domain and frequency domain waveform characteristics of transient voltage and current for the faults inside and outside the dc lines, Exploring the one-end and two-end based fast protection principles of dc line, and the identification method of disturbance signals; 2) For the different fault types of pole to ground / pole-to-pole faults, the coupled voltage on the isolated faulty line will be analyzed, and the criterion distinguishing the temporary fault from the permanent fault will be further constructed; The control strategy based on DC CB injecting signal will be designed, and the propagation characteristics of signal will be analyzed, furthermore, the identification method of temporary and permanent faults will be proposed, ultimately the adaptive reclosure scheme will be present; 3) The topologies and control strategies of multi-port and multi-function DC CBs will be studied; 4) Base on the aforementioned theoritical results, the experimental prototypes of relay and novel DC CB will be made. Through the principle study and prototypes make, the technical support for the fast isolation of dc side fault of DC grid will be provided.