小电流接地系统选择性漏电保护器的研究

发布时间：2018-05-23 22:15

本文选题：小电流接地系统 + 消弧线圈　；参考：《辽宁工程技术大学》2014年硕士论文

【摘要】：我国3～66kV供电系统主要以小电流接地方式为主,利用中性点非有效接地的特点,减小单相接地时造成的危害。小电流接地系统发生单相接地故障时,由于接地电流较小故障特征微弱而且受环境噪声等外界干扰影响较大,易造成选线误判。近些年很多学者对小电流系统接地故障做了大量的深入研究,提出了很多选线判据,但是实际的应用效果并不理想,这严重制约着我国供电系统智能化的发展。随着安全生产对供电可靠性要求的逐步提高,亟待提出一种准确可靠的选线方法。本文详细分析了小电流接地系统单相接地故障的特性,分别对中性点不接地系统、中性点经高阻接地系统和中性点经消弧线圈接地系统发生故障时的零序特征量进行了研究,重点分析了在不同接地系统中零序电压和零序电流的相位关系。根据零序参数的特征,本文应用“零序无功+有功功率”算法实现小电流接地选线,并以MATLAB为平台搭建供电系统模型,进行单相接地故障仿真。选择性漏电保护器的硬件电路以16位单片机MC9S12XS128MAA为控制核心,数据处理能力强,内置12位AD转换器,简化外围电路。为了克服小电流系统接地故障时零序特征量幅值变化范围大、检测困难的问题,加入程控放大器,提高检测灵敏度,扩大检测范围。试验证明,该方案可有效提高选择性漏电保护器的可靠性和灵敏性。
[Abstract]:The main mode of 3~66kV power supply system in our country is small current grounding, and the harm caused by single-phase grounding is reduced by using the characteristics of non-effective neutral grounding. When a single-phase grounding fault occurs in a low-current grounding system, it is easy to misjudge the line selection due to the weak fault characteristics of the grounding current and the strong influence of environmental noise and other external interference. In recent years, many scholars have done a lot of in-depth research on the ground fault of small current system, and put forward many criteria of line selection, but the actual application effect is not ideal, which seriously restricts the development of intelligent power supply system in China. With the improvement of reliability requirement of power supply in safety production, it is urgent to put forward an accurate and reliable route selection method. In this paper, the characteristics of single-phase grounding fault of small current grounding system are analyzed in detail. The zero sequence characteristic quantities of neutral point ungrounded system, neutral point grounding system through high resistance and neutral point grounding system through arc-suppression coil are studied respectively. The phase relationship between zero sequence voltage and zero sequence current in different grounding systems is analyzed. According to the characteristics of zero-sequence parameters, this paper applies the "zero-sequence reactive power" algorithm to realize the low-current grounding line selection, and builds the power supply system model based on MATLAB to simulate the single-phase grounding fault. The hardware circuit of the selective leakage protector is based on 16-bit single-chip computer (MC9S12XS128MAA), which has strong data processing ability and 12 bits AD converter, which simplifies the peripheral circuit. In order to overcome the problem that the amplitude of zero sequence characteristic quantity changes in large range and it is difficult to detect the ground fault of small current system, the program control amplifier is added to improve the detection sensitivity and expand the detection range. The test results show that this scheme can effectively improve the reliability and sensitivity of the selective leakage protector.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM862;TM564.8

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