风电场35kV电缆网中性点接地方式研究

发布时间：2018-04-13 19:10

本文选题：风电场 + 电缆网　；参考：《重庆大学》2014年硕士论文

【摘要】：风电场由于受地形、环境等影响，35kV集电系统越来越多的选择电缆线路。随着风电场规模增大，电缆长度增加，导致系统电容电流水平较高，当系统发生单相接地故障时，会严重威胁电气设备绝缘。因电力系统的中性点运行方式和单相接地故障关系非常的密切，故选择合适的中性点运行方式可以灵活的提高35kV系统运行的可靠性以及经济性，对提高风电场安全运行水平拥有重要的意义。论文以龙里风电场为研究对象，基于Matlab/Simulink平台建立仿真计算模型，考虑接地故障时刻、接地故障点位置、接地故障点过渡电阻及接地电容电流四种影响因素下，中性点不接地、经消弧线圈接地和经小电阻接地时，电缆网发生接地故障的过电压和过电流水平，通过对比分析，得出适合风电场35kV电缆网的中性点接地方式。主要成果有： ①对比不同运行方式下电缆网的运行效果，中性点采用消弧线圈接地时能实现对接地电容电流的有效补偿，起到快速消弧的效果；中性点经小电阻接地能够抑制故障暂态过电压，并可利用零序过流保护快速切除故障。 ②以消弧线圈接地为基础配合小电阻接地的中性点接地方式，综合了中性点经消弧线圈接地快速消弧和中性点经小电阻接地快速切除故障线路的优点；通过对改进的中性点接地方式的暂态过程进行仿真，其暂态投切不会对系统造成冲击，不影响设备安全运行。基于风电场35kV电缆网的特点，得出一种适合该电缆网的中性点接地方式，即以消弧线圈接地为基础，对于接地电容电流水平小于100A的电缆网，当单相接地故障发生时，首先利用中电阻限制其暂态过电压水平，，如果是瞬时性故障，消弧线圈进行补偿后故障自动消除，若是非瞬时性故障则利用短时并入小电阻增大接地点电流，启动保护装置快速切除故障线路；对于无需采用暂态过电压抑制措施的接地电容电流大于100A的电缆网，当发生非瞬时性接地故障时，利用小电阻的短时投入启动零序过流保护装置快速切除故障。
[Abstract]:Due to the influence of topography and environment, more and more cable lines are chosen for 35 kV collector system.With the increase of wind farm scale and the increase of cable length, the capacitance current level of the system is higher. When the single-phase grounding fault occurs, the insulation of electrical equipment will be seriously threatened.Because the neutral operation mode of power system is closely related to the single-phase grounding fault, choosing the proper neutral operation mode can flexibly improve the reliability and economy of 35kV system operation.It is of great significance to improve the safe operation level of wind farm.This paper takes Longli wind farm as the research object, establishes the simulation calculation model based on the Matlab/Simulink platform, considering the time of the grounding fault, the location of the grounding fault point, the transition resistance of the grounding fault point and the grounding capacitance current, the neutral point is not grounded.When grounding through arc-suppression coil and grounding with small resistance, the overvoltage and over-current level of grounding fault occurred in cable network. Through comparison and analysis, the neutral grounding mode suitable for 35kV cable network in wind farm was obtained.The main results are:1 comparing the operation effect of cable network under different operation modes, when neutral point is grounded by arc suppression coil, it can realize effective compensation of grounding capacitance current and play the effect of fast arc suppression;The fault transient overvoltage can be suppressed by the neutral point grounding with small resistance, and the fault can be quickly removed by zero-sequence over-current protection.(2) on the basis of arc-suppression coil grounding with small resistance grounding, the advantages of fast arc suppression through arc-suppression coil grounding and fast fault line removal of neutral point through small resistance earthing are integrated;By simulating the transient process of the improved neutral grounding mode, the transient switching will not impact the system and will not affect the safe operation of the equipment.Based on the characteristics of 35kV cable network in wind farm, a neutral grounding mode suitable for the cable network is obtained, that is, based on arc-suppression coil grounding, when the grounding capacitance current level is less than 100A, when the single-phase grounding fault occurs,First, the transient overvoltage level is limited by medium resistance. If it is a transient fault, the arc suppression coil compensates for the fault and automatically eliminates the fault. If the transient fault is non-instantaneous, the transient current is increased by incorporating a small resistor in a short period of time.The fault line is removed quickly by starting the protective device, and for the cable network with grounding capacitance current greater than 100A which does not require transient overvoltage suppression, when a non-instantaneous grounding fault occurs,Using the short-time input of small resistance to start the zero-sequence overcurrent protection device, the fault can be quickly removed.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614;TM862

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