矿井电网漏电暂态特征分析及仿真

Analysis and simulation of leakage transient in coal mine low voltage network

为了便于利用暂态特征实现矿井电网漏电识别的快速性与可靠性,建立了矿井低压电网单相漏电暂态过程的数学模型,分析获得了漏电的零序电压、零序电流、接地电流、各相对地电压等的动态时域数学描述。以某矿井660V电网为例,利用Matlab的Simulink软件包,搭建了接近实际的漏电模型;对理论建模分析的正确性,不同漏电电阻、不同漏电角、不同漏电点和线路长度等与漏电特征之间的关系等进行了大量仿真;仿真波形的重合性和相似度证明了理论建模的正确性。在暂态过渡阶段,零序电压、零序电流及它们冲击值等随漏电电阻的增大而减小,而受漏电角变化的影响较大;同时,故障障线路的零序电流的波形态势(极性、大小、冲击值、衰变过程)和非故障支路的明显不同,这一暂态特征不受漏电电阻、漏电角、漏电点、线路长度等因素的影响。这些为矿井电网的判漏和选漏的研究提供了理论依据。

In order to realize rapid and reliable idenfification of coal mine low voltage distribution network leakage using transient charicteristics conveniently, transient mathematical model of coal mine single-phase leakage is established, the instantaneous expressions of zero-sequence voltage, zero-sequence current, ground current and phase-ground vlotages are all presented through analysis for that. By simulink of MATLAB, a practical 660 V coal mine distribution network simulation model is set up; the relationships between leakage charicteristics and different leakage resistances, leakage angles, leakage points and different line length are simulated; validity of theory model analysis is done also. The superposition and high similarity of leakage wave forms confirm that theroy analysis model is correct. In transient transition course, zero-sequence voltage, zero-sequence currents and their impact values decrease with the increase of leakage resistance, and are influenced by leakage angle; transient zero-sequence current waveform（including ploarity, dimension, impact value, and decay process）of fault line is quite different from nomal lines’, and this feature is not influenced by leakage resistances, leakage angles, leakage points, and line length. These results provide theroy evidences for research of coal mine leakage protection.