发电厂接地装置热稳定校核方法

Thermal Stability Checking Method of Grounding Device in Power Plant

由于近几年准格尔地区电网结构改变,电力系统容量增加,系统阻抗变小,发电厂若发生接地短路故障,故障电流变化较大。为确保内蒙古国华准格尔发电厂电气设备的安全稳定运行,有必要再次对发电厂接地装置进行热稳定校核。根据DL/T 621—1997《交流电气装置的接地》要求,在不考虑地网腐蚀的情况下计算流过接地网的最大短路电流,依据接地网热稳定校验公式,校验接地网是否满足热稳定要求。校验结果表明,国华准格尔发电厂接地装置满足热稳定要求,并建议对发电厂内不同区域的接地网进行多处开挖取样,根据接地网的实际腐蚀情况进行接地体截面积计算及材料的选择,使接地体在遭受腐蚀的情况下仍有足够的热稳定截面。

In recent years,because of the change of Guohua zhung＇er power network structure,the increase of power system capacity,the decrescent of system impedance,if earthing short circuit fault occurred in power plant,fault current would change greatly.To ensure electrical equipment＇s safe and stable operation in Inner Mongolia Guohua zhung＇er power plant,it is necessary to check the thermal stability of power plant grounding device.According to the DL/T 621—1997 AC electrical device grounding requirement,without considering the grounding grid corrosion condition,to calculate the maximum short-circuit current through the grounding grid.According to grounding grid thermal stability check formula,ensure the grounding grid to meet the requirements of thermal stability.Check results show that grounding device in Guohua zhung＇er power plant meet thermal stability requirement.in different areas mat in excavation sampling,according to actual corrosion of grounding grid to calculate material selection,the grounding body subjected to corrosion situation still have enough thermal stability cross section.