交流输电线路双端行波测距方法研究

发布时间：2018-01-22 03:02

本文关键词： 输电线路故障测距行波神经网络小波变换　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：电力系统的容量不断扩大和电网区域快速扩展,使电网的管理和运行控制变得更加复杂,其安全性及稳定性问题也日渐凸显。电力系统故障所造成的破坏的后果往往与电力故障被处理及恢复的速度相关。如果故障得不到及时处理,其造成的危害可能非常严重。故障发生后实现快速、精确的故障定位,能最小范围的隔离故障元件,实现最大范围的正常供电。所以,故障定位的速度和准度对电力系统经济性、稳定性和安全性都至关重要。本文围绕着利用衰减和变形的行波波头信息来进行输电线路故障测距的思路展开研究,以实现精确故障测距为宗旨,并且研究其在各种不利因素的影响下稳定工作的可靠性。本文所做的具体工作内容如下:(1)行波原理的基本分析及其相关特性研究通过MATLAB对实际输电线路系统进行仿真分析,得到线路依频参数,通过解耦分析,最终得到模量参数的变化趋势。零模电阻、电感参数对零模行波分量有比较大的影响,当频率增大时,零模电阻值正相关变大,而电感值为负相关变小;但是线模电感几乎不变化,线模电阻值正相关缓慢地变大。从而零模分量的波速度及衰减常数受频率的影响比线模的要大的多,即零模分量在传播过程中波速更慢,衰减及变形程度也更大。(2)输电线路双端行波测距方法零模故障分量在故障点产生行波为阶跃信号,然后沿着输电线路向线路两端传播的过程中发生衰减和变形,该衰减和变形的第一个波头中就包含着丰富的信息,利用数学模型提取该波头上的故障特征,从而取得故障测距结果。但是,很难得到该首波头中各个频率分量对应的幅值。将某指定分量对应的频率设置为中心频率,作大尺度下的小波变换,然后得到其模极大值,利用两端此频率分量的模极大值的比值表征双端对应的频率分量幅值之比。虽然线路两端指定频率分量的模极大值的比值和其幅值之比是一一对应的关系,但毕竟不是相等关系,所以本文选取RBF网络来刻画这种对应关系。最后通过PSCAD算例模型对所提算法进行仿真及验证,此方法具有很高的可行性,采样时间窗比较窄,并且不用考虑初始波头的后续波的影响。(3)影响测距结果各因素敏感性分析通过对故障发生时故障类型、过渡电阻和初相角等影响故障点初始行波产生问题的主要因素及采样率和训练样本对测距结果的分析,以PSCAD/EMTDC搭建仿真模型分析出在上述各因素影响下,本文测距方法能可靠的得出准确的测距结果,但是本文只对交流架空线路进行研究,未涉及配网及特高压线路的研究,所以还需拓宽涉及面以研究其可行性。(4)分接线对其结果的影响及改进方法研究详细分析了分接线对本文所提测距算法的产生的影响并就此提出实际的解决方法。得到了下述结论:第一、本文假定分接线与输电线路MN同参,行波首波头沿MN传播到波阻抗不连续的分接点时发生折、反射,使其幅值变小,但是形状未变。这样线路两端的幅值就不再对应,需要对经过分接点衰减的一侧的幅值进行修正。此方法实施的前提是必须明确故障发生在具体哪个区段。第二、波头的衰减和变形与其频率相关,故而输电线路上不同位置发生故障时到达线路两端测量点的波头具有不同的形状,这样就刻画了波头形状与故障位置的一一对应关系。采用数学定义——突变波形系数来描述此关系,它刻画的是波头衰减和变形的形状,与大小无关,即不用再刻意去对初始波头幅值进行校正。最后利用仿真校验了此方法的可靠性。
[Abstract]:The capacity of the power system and power grid expanding area of rapid expansion, the management and operation of the power grid control becomes more complex, the problem of security and stability are increasingly prominent. The power system failure caused by the destruction of the consequences of power failure is often associated with treatment and recovery rate. If the fault can not get timely treatment, harm the result may be very serious. Fast fault occurs, precise fault location, fault isolation can minimum range of components, to achieve the maximum range of the normal power supply. Therefore, the speed and the accuracy of the fault location of power system are important economic force, stability and safety. This paper focuses on the fault location of transmission to the attenuation and distortion of the line by the head of traveling wave information the idea of the study, in order to achieve accurate fault location for the purpose, and study the various unfavorable factors under the influence of Stable and reliable work. The specific content of the work done in this paper are as follows: (1) the basic principle of the traveling wave analysis and its characteristic research by MATLAB on the actual transmission line system simulation analysis, line frequency parameters, by decoupling analysis, finally get the changing trend of modulus parameters. Zero mode resistance, inductance effect the larger of the zero mode traveling wave, when the frequency increases, the resistance value is zero mode becomes larger, and the inductance value is negative but smaller; line mode inductance hardly changes, the resistance value is positively related to die slowly. The wave speed to zero mode component and attenuation constant frequency effect of greater than the line mode, namely zero mode component in the process of propagation velocity decay more slowly, and the deformation degree is greater. (2) transmission line double terminal traveling wave fault location method of zero mode traveling wave fault components at the fault point for the step signal, however Along the transmission line to line ends in the spread of decay and deformation, the attenuation and distortion of the first wave head contains abundant information, extract the wave head of the fault feature by using mathematics model to obtain the fault location results. However, it is difficult to get the amplitude of the first wave head in each frequency a component corresponding to the specified component. The corresponding frequency is set to the center frequency of wavelet transform in large scale, and then get the modulus maxima using two the frequency components of the modulus maximum frequency component amplitude ratio of double end corresponding ratio. Although the relationship between the ratio of the specified frequency component at both ends of the line at the maximum the value and the amplitude ratio is one-to-one, but not equal, so this paper selects RBF network to describe this relationship. Finally through the example of PSCAD model is used to simulate the proposed algorithm And verification, this method has high feasibility, sampling time window is relatively narrow, and do not consider the initial wave head of subsequent wave effects. (3) effects of ranging results of the factors through the sensitivity analysis of fault fault types, analysis of the main factors affecting the initial phase of the transition resistance and fault point of initial traveling wave problems and the sampling rate and the training samples on the measurement results, analysis of the impact of these factors on PSCAD/EMTDC in the simulation model, the ranging method can obtain accurate and reliable measurement results, but this paper only on the AC overhead line of research does not involve the distribution network and the UHV transmission line, so it is necessary to broaden the covers in order to study its feasibility. (4) research and improvement effect on the results of a detailed analysis of the connection points of the connection location algorithm and puts forward the actual impact Solution. Get the following conclusion: first, this paper assumes that the branch connection and transmission line MN with ginseng, fold, the first wave traveling wave occurred along the MN spread to wave impedance discontinuity points point reflection, the amplitude becomes smaller, but the shape unchanged. This amplitude at both ends of the transmission line will no longer need to correspond after one side of the contact amplitude attenuation correction. This method is the premise of implementation must be clear fault occur in any specific section. Second, the head wave attenuation and distortion and frequency, and transmission line fault occurs at different positions on the wave head line at both ends of the road with different shapes, such as characterization the head wave shape and fault location. The correspondence between mathematical definition - waveform coefficients to describe the mutation of this relationship, it is a portrait of the shape of head wave attenuation and distortion, and size, not to deliberately The amplitude of the initial wave head is corrected. Finally, the reliability of the method is verified by simulation.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM75

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