【作者】 郭剑；

【导师】 何金良；

【作者基本信息】 清华大学 ， 电气工程， 2005， 博士

【摘要】 正确了解接地装置在雷电流作用下的冲击特性是电力系统及建筑物雷电防护的基础。目前国内外现有的研究方法不能同时考虑接地系统暂态响应的时频特性。本文采用时域频域双内插算法合成接地系统的全时域暂态特性,能够有效地处理接地系统的暂态响应的时频特性,改善了以往算法中准确度和效率之间的矛盾。首先,本文提出了基于电路理论的扩展不等电位模型法来计算地网暂态的早时响应。该时域计算方法将地网导体间的对地互阻抗考虑进计算模型中,并在此基础上发展了能够考虑土壤电离效应的算法。在将其进一步发展为电路模型后,采用基于电路模型的Bergeron算法进行计算,可完成地网暂态的早时响应计算。水平多层土壤中的电流场的计算方法较复杂。根据电流场的边界条件和格林函数表达式通式,本文提出一种计算机自动推导多层土壤格林函数表达式的方法,从而避免了传统方法中需要人工推导公式带来的问题,使多层土壤中电流场的计算更加方便。然后本文设计了一维和多维的两阶段自适应采样智能模型拟合算法,提出了基于智能模型拟合算法的接地系统在冲击电流激励下的晚时频域响应计算模型。在不损失计算准确度的前提下,使接地系统暂态计算的频域计算部分的整体效率提高20倍左右,有效地提高了计算速度。最后,本文提出了能够兼顾接地系统时变特性和频变特性的暂态全时响应计算模型,并根据接地网暂态计算的特点,建立了将该模型应用于接地系统暂态仿真前的预处理过程。通过与水平接地极和水平接地网的冲击特性试验结果相比较,验证了论文提出的分析方法的准确性。同时,本文将提出的方法应用于接地系统雷电暂态特性分析中。通过模拟计算,得出了不同雷电流波形、不同接地网尺寸、不同土壤结构以及不同引流方式等各种因素对接地系统冲击特性的影响规律。更多还原

【Abstract】 Correctly realizing the lightning transient performances of grounding devices isthe foundament of lightning protections of power system and buildings. At present,the developed methods are still difficult to take into account both the time-variant andfrequency-variant characteristics of the grounding girds. The dissertation proposed amethod based on the Hermite primary function, which interpolates in both the timedomain and frequency domain. It can efficiently handle calculating the transientresponses of grounding grids, and get rid of the contradiction between the precisionand the efficiency to some extent.At first, a method called extended unequal potential method is proposed in thisdissertation to obtain correct early time data. It takes into account both the mutualimpedance to ground among grounding conductors and the effect of the ionization inthe soil. The method can be applied with the Bergeron method by transferring thegrounding system into a circuit model.The calculations of the current field in multi-layer soil are difficult. According tothe boundary conditions and the general expressions of Green’s Functions,a recursivemethod to obtain the exact expressions of Green’s Functions in multi-layer earth ispresented in this dissertation. It avoids the error brought by manual deduction andmakes the calculations of the current field in multi-layer soil more precise.To the purpose of the full-time response, the late time data are also necessary.One dimensional and multi-dimensional two-stage adaptive sampling methods aredesigned in this dissertation. And then, a method based on the union of the traditionalmethod of moments and the intelligent fitting model is proposed in this dissertation. Itcan accelerate the grounding transient calculation by 20 times without any precisionloss.At last, the analysis method of transient full-time response was proposed, whichcan take into account both the time-variant and frequency-variant characteristics ofthe grounding girds simultaneously. According to the particularity of the transientsimulation of grounding systems, a group of preprocesses are constructed for themethod to be applied better in the grounding transient simulation. The experimentalresults verified the precision of the method described in this dissertation.Otherwise, the methods discussed in this dissertation were applied to analyze thetransient characteristics of grounding grids. Detailed conclusions about the transientcharacteristics of grounding systems under versatile lightning waveform, grids size,soil, and current conducting way were drawn.更多还原