电压暂降监测点优化配置及暂降数据压缩研究

发布时间：2018-03-16 04:00

本文选题：电压暂降　切入点：改进MRA法　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代电网中敏感负荷所占的比重不断增大,电能质量问题越来越受到人们的关注。在所有电能质量问题的投诉中,电压暂降所占的比重最大。系统中短路故障的不可预知性造成了电压暂降的随机性,进而对系统中敏感设备的正常工作状态产生影响,造成电力用户的经济损失。因此针对含有多个电压等级的实际配电网做到电压暂降的全面可观测对于减小电力用户的经济损失、提升供电质量具有重要的现实意义。考虑到电能质量监测设备的成本投入,在保证电压暂降可观测的前提下,力求选取的监测点最少。在确定电压暂降监测点优化配置方案以后,如何有效解决监测点电压暂降检测数据量庞大,难于存储和传输的问题,是一个极具应用价值的研究方向。本文主要针对以上两个问题,对电压暂降监测点优化配置及暂降数据压缩方法做出了研究。提出基于改进MRA法的电压暂降监测点优化配置方法。将系统中的母线按照电压等级进行分类,根据监测母线与被监测线路相对位置关系确定零序阻抗矩阵,克服了传统方法构建单一零序阻抗矩阵的缺点。根据变压器的接线方式以及系统是否有效接地对电压暂降幅值进行修正。针对已有MRA法采用的仿真算例主要为标准节点测试系统的问题,本文采用含有4个电压等级的实际配电网进行仿真分析。通过将本文所提方法与已有MRA法所得结果进行对比表明,本文所提的方法能够解决已有MRA法对实际配电网进行优化配置时存在监测盲区的问题,有效对含有多个电压等级的实际配电网进行电压暂降监测点优化配置。在优化配置的基础上,相较于传统凹陷域以敏感负荷为中心,本文采用以故障点为中心的同心松弛凹陷域计算方法计算凹陷域。同心松弛凹陷域计算方法能够有效地减少供电部门凹陷域计算的工作量,为电压暂降产生的责任划分问题提供解决依据。针对现阶段电压暂降检测数据量庞大,难于存储与传输的问题,本文将压缩感知理论应用于电压暂降信号的采集与传输中。电压暂降信号的重构算法采用正交匹配追踪算法,通过对不同压缩采样比情况下电压暂降信号恢复效果进行对比,得出采样点数越高,重构效果越好的结论。在以FFT作为稀疏基的条件下,通过选取不同的测量矩阵来对电压暂降信号进行重构,经过仿真试验发现,部分哈达玛矩阵的重构效果最好。为进一步探究信号的稀疏度K对电压暂降信号的重构效果的影响,本文通过在正交匹配追踪算法中设置不同的稀疏度K,将得到的算法重构效果进行对比,得出信号的稀疏度K的选取对重构的效果有很大影响的结论。通过仿真分析,证明了本文所提的基于压缩感知理论的电压暂降数据压缩方法的有效性。
[Abstract]:With the increasing proportion of sensitive load in modern power grid, people pay more and more attention to the problem of power quality. The unpredictability of the short-circuit fault in the system causes the randomness of the voltage sag, which in turn affects the normal working state of the sensitive equipment in the system. Therefore, for the actual distribution network with multiple voltage levels, the overall observable voltage sag can reduce the economic loss of the power users. It is of great practical significance to improve the quality of power supply. Considering the cost of power quality monitoring equipment, the voltage sag can be observed on the premise that the voltage sag can be observed. After determining the optimal configuration scheme of voltage sag monitoring point, how to effectively solve the problem of large amount of data of voltage sag detection at monitoring point, which is difficult to store and transmit, This paper focuses on the above two problems. The optimal configuration of voltage sag monitoring points and the method of data compression are studied. A method of optimal configuration of voltage sag monitoring points based on improved MRA method is proposed. The busbar in the system is classified according to the voltage grade. The zero-sequence impedance matrix is determined according to the relative position between the monitoring bus and the monitored line. It overcomes the shortcoming of the traditional method of constructing a single zero-sequence impedance matrix. According to the connection mode of the transformer and whether the system is effectively grounded, the voltage temporary drop value is corrected. The simulation example used in the existing MRA method is mainly used as the standard. The problem of quasi-node test system, In this paper, the actual distribution network with four voltage levels is used for simulation and analysis. By comparing the proposed method with the results obtained by the existing MRA method, it is shown that, The method proposed in this paper can solve the problem of monitoring blind area when MRA method is used to optimize the distribution network. The optimal configuration of voltage sag monitoring points for the actual distribution network with multiple voltage levels is effectively carried out. On the basis of the optimized configuration, the sensitive load is the center of the traditional sag region. In this paper, the calculation method of concentric relaxation sag region, which is centered on fault point, is used to calculate the sag region. The calculation method of concentric relaxation sag domain can effectively reduce the workload of calculation of the sag region in power supply department. In order to solve the problem of responsibility division caused by voltage sag, it is difficult to store and transmit the large amount of data in voltage sag detection at the present stage. In this paper, the theory of compression sensing is applied to the acquisition and transmission of voltage sag signal. The reconstruction algorithm of voltage sag signal adopts orthogonal matching tracing algorithm, and the effect of voltage sag signal recovery under different compression sampling ratio is compared. It is concluded that the higher the sampling number is, the better the reconstruction effect is. Under the condition that FFT is used as the sparse basis, different measurement matrices are selected to reconstruct the voltage sag signal, and the simulation results show that, In order to further investigate the effect of signal sparsity K on the reconstruction effect of voltage sag signal, part of Hadamard matrix is the best. In this paper, by setting different sparse degree K in orthogonal matching tracking algorithm, the reconstruction effect of the algorithm is compared, and it is concluded that the selection of signal sparsity K has great influence on the reconstruction effect. The validity of the voltage sag data compression method proposed in this paper based on compression sensing theory is proved.
【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】：TM714.2

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