基于限流电感电压的多端交直流混合配电网直流故障检测方案

直流故障的快速准确检测是多端交直流混合配电网亟需发展的关键技术之一。直流故障电流上升速度快、故障影响范围广,传统的交流故障检测方法不再适用于直流故障。该文提出一种基于直流线路限流电感电压变化率的多端交直流混合配电网直流故障快速检测方案。首先,详细分析了多端交直流混合配电网的直流故障特性,在此基础上,提出了利用直流线路单端限流电感电压变化率检测直流故障的方法。接着,设计了完整的识别故障线路、判断故障类型和故障极的故障检测方案,并研究了相应的阈值选取方法。最后,通过MATLAB仿真平台对所提故障检测方案进行了仿真验证,仿真结果表明所提方法不受过渡电阻、故障距离、以及换流站功率反转的影响,能够在故障后迅速确定故障线路、故障类型以及故障极,实现直流故障的快速准确检测,为多端交直流混合配电网保护系统的设计奠定了基础。

DC Fault Detection Scheme for Multi-terminal Hybrid AC/DC Distribution Network Based on Current-limiting Inductor Voltage

Rapid and accurate detection of DC faults is a key technologies for development of multi-terminal hybrid AC/DC distribution networks. DC fault currents rise rapidly after DC fault and traditional AC fault detection methods are no longer suitable for DC faults. A DC fault detection scheme based on voltage change rate of DC current-limiting inductor for multi-terminal hybrid AC/DC distribution network is proposed in this paper. Firstly, the characteristics of DC faults are analyzed thoroughly. Based on this, a method detecting DC faults using single-end current-limiting inductor voltage change rate is proposed. Secondly, a comprehensive fault detection scheme identifying faulty line, fault type and faulty pole is designed, and corresponding threshold selection method is studied in detail. Finally, the proposed fault detection scheme is verified with MATLAB simulations. Simulation results show that the proposed scheme is accurate and fast enough for different fault resistances and different fault distances, not affected by power reversal of the converters.