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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
The fault characteristic of overcurrent in power network is analyzed and the working principle of overcurrent protection system is described.The method of determining the characteristic curve of symmetrical short circuit phase sensitive protection is introduced emphatically.The negative sequence current filter is designed and the mathematical model of overload protection The hardware structure and software block diagram of overcurrent protection system with SCM as central control unit are given, the protection system is tested before going down well, the operation index meets the design requirements, the protection sensitivity is increased and the protection scope is increased. It shows that the protection system has stable performance and reliable operation and has important application value