【作者】 王辉；

【导师】 张庆超；

【作者基本信息】 天津大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 电力系统中性点接地方式是一个非常综合的技术问题,它与电网电压等级、电网结构、绝缘水平、供电可靠性、继电保护、电磁干扰、人身安全都有很大的关系。过去我国10kV配电网主要采用中性点不接地和经消弧线圈接地方式,80年代中后期为适应城区电网的迅速发展,特别是电缆的大量使用后,出现了l0kV配电网中性点经低电阻接地方式,该运行方式先后在许多大中城市如广州、上海、北京、珠海等地采用。经多年的运行实践,各地普通认为低电阻接地方式比消弧线圈接地方式的过电压水平要低,但同时反映出的运行状况也存在较多的问题,主要是供电可靠性有所下降,还曾发生过多起人身伤亡事故。因此国内目前在10kV电网中性点接地运行方式的选择上出现较大的争议,争议点主要是两种接地方式的应用范围、供电可靠性的高低、人身安全、通信干扰和运行维护工作量等诸多方面。本论文主要针对10kV配电网中性点接地运行方式的选择问题进行研究。论文首先对10kV配电网的中性点各种运行方式进行分析,比较不同运行方式的特点。然后以茅坪变电站10kV电网的实际参数来建立数值计算模型,在考虑了电网接地电容电流变化、接地点接地电阻值变化等多种影响因素的情况下,对中性点经消弧线圈接地和经低电阻接地方式下电网的过电压水平和接地点短路电流大小进行了仿真和计算,同时对各种接地方式对弧光过电压的限制也作了分析。本文还计算了经消弧线圈接地方式下消弧线圈及相关设备的技术参数,做出合理选择,并最终实现消弧线圈接地的自动跟踪补偿。更多还原

【Abstract】 It is an important technical problem to neutral grounding mode of the electric power system which associates with voltage level, network structure, insulation level, reliability of power supply, protective relaying, electromagnetic interference, and personal safety.In China, the neutral grounding mode of the 10kV network used of none grounding, grounding by arc suppressing coils in the past. With the development of urban power network, especially the widespread use of cables, low resistance grounding mode was used to restrain the over voltage in Guangzhou, Shanghai, Beijing, and Zhuhai etc. It was reported that the over voltage level of low resistance grounding mode is lower than that of arc suppressing coil mode, but the operation carried out the other problems, including reliability of power supply rapidly dropping, and person safety being threatened. So interiorly the grounding mode selection of the 10kV network was disputed, which mainly focused on the fault form of 10kV network grounding, the apply area of arc suppressing coil grounding mode and low resistance grounding mode, reliability of power supply, person safety, communication interference and the work load of maintenance.This paper studied on how to select the neutral grounding mode of 10kV network. Firstly it analyzed the characteristic of grounding modes about 10kV network. Then with the demonstration of Maoping substation in Hubei province, this paper built a numerical value equivalent model. Taking account of the transformation of the capacitive current or the variety of the grounding point resistance, it simulated the over voltage level and the grounding point short current value of the network with arc suppressing coil grounding mode or low resistance grounding mode, in addition, this paper discussed the problem of restrained arc over voltage.In this paper , the technical parameters for the arc suppressing coil and associated equipment were calculated , and reasonable selection has been made to finally realize automatic tracing compensation for arc suppressing coil grounding mode.更多还原