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摘 要 煤矿井下低压供电系统为小电流接地系统，煤矿井下工作条件复杂，一旦发生漏电易引发瓦斯或煤尘爆炸及人员触电事故，所以煤矿井供电系统应装设性能良好的漏电保护装置。选择性漏电保护是指当供电网络出现漏电现象时，能够单独对出现漏电现象的线路进行保护动作，不再向漏电支路提供电能，其他正常运行的支路继续工作，预防故障的扩大，也使系统运行更加安全可靠。 矿井下电网工作环境相对恶劣，因此，漏电保护的可靠性，速动性和选择性就受到了很大的挑战。本文使用多种方式结合的方法将附加直流电源检测和零序功率方向方式一起配合。该漏电保护系统在总控制保护器处采用附加直流电源检测的方法，在分支电保护器处采用零序功率方向的保护方法，这种漏电保护系统设计的方法比传统的保护方式设计更简单可靠，提高了井下恶劣情况漏电保护设计在的实用性，达到漏电保护设备的安全指标。 37748
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毕业论文关键字： 矿井低压系统 选择性 漏电保护 零序功率
Abstract The low voltage power supply system of coal mine is a small current grounding system, coal mine working condition is complex, In case of leakage easily lead to gas or coal dust explosion and electric shock accident, so coal mine power supply system should install leakage protection device with good performance. The selectivity leakage protective system can give out alarming signal or cut off the fault branches selectively when the leakage fault happens, Other normal running branches continue to work. It can prevent the accident to expand , and also makes the system more stable and reliable operation Environment of the underground low voltage distribution system is relatively poor, and therefore, leakage protection reliability, speed and mobility and selectivity on has been a great challenge. This paper advance a new scheme which based on additional DC power supply and direction of zero sequence power. The principle of the additional DC power source in the device is used for the main feed switch, and the principle of direction of zero sequence power is used in branch feeding switch. The method of selective protection than the traditional design of leakage protection device is more simple and reliable, the practicability of leakage protection device under the adverse circumstances is be improved, the safety indexes of leakage protection equipment is easy to reached.
Key Words : underground low voltage distribution networks selectivity leakage-protection zero sequence power
目录
摘要.I
AbstractII
1绪论.1
1.1漏电保护研究的意义1
1.2国内外发展及状况1
1.3本文的主要研究内容2
2矿井低压供电系统漏电分析3
2.1特殊的供电方式3
2.1.1电网电压等级3
2.1.2供电的独立性3
2.1.3中性点不接地3
2.1.4井下低压电气模型4
2.2基本电网漏电分析5
2.3单相漏电各故障参数变化6
2.3.1零序电压分析6
2.3.2零序电流分析8
2.3.3漏电电流9
2.4选择性原理.10
2.5选择性漏电的保护方法分析.12
2.5.1零序电流幅值法.12
2.5.2附加直流电源法.13
2.5.3零序电压保护法.14
2.5.4零序功率方向保护法.15
3选择性漏电保护装置的硬件设计17
3.1总体设计方案.17
3.2系统设计.19
3.3中央处理模块.20
3.4开关量输入输出.22
3.5模拟量输入.23