【摘要】 分析了电网中过电流的故障特征 ,描述了过电流保护系统的工作原理 .重点介绍了对称短路相敏保护特性曲线的确定方法 ,设计了负序电流滤波器 ,建立了过负荷保护的数学模型 .给出了以单片机为中央控制单元所构成过电流保护系统的硬件结构和软件框图 ,下井前对保护系统进行了试验 ,动作指标符合设计要求 ,提高了保护灵敏度 ,增加了保护范围 .现场运行表明 ,该保护系统性能稳定 ,动作可靠 ,具有重要的应用价值更多还原

【Abstract】 The overcurrent fault characters in underground LV cable distribution networks is analyzed and the fundamental principle of overcurrent protective system is narrated in this paper. Much more attention is paid to the analysis of the method how to define the characteristic curves of phase sensitive symmetrical short circuit protection, the design of negative sequence current filter and the definition of the mathematical model of overload. Besides, the hardware block diagram and software flowchart of the protective system controlled by single chip microcomputer is also introduced in the paper. The protective system was tested before applied in underground LV distribution networks, The results obtained are conformity with the design specification. It has been verified that the protective distance is enlarged and the protective sensitivity is improved with the protective system. The field experience has shown that the protective system is good practice in stability and reliability, and will be of great applied value in mining industry.更多还原