【作者】 陈灿；

【导师】 梁志坚；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2017， 硕士

【摘要】 分布式电源作为集中式发电大电网的补充和完善,以其清洁环保、可持续、灵活等优势在我国得到了快速发展和应用。然而,随着分布式电源大量地接入到配电网并网运行,配电网的网络结构将发生改变,潮流方向不再具有单一性。因此,含分布式电源的配电网故障定位问题会更加复杂化,本文主要针对这个问题来进行分析研究。首先,本文介绍了目前国内外有关配电网故障定位算法研究的现状、分布式电源相关概念和并网要求,阐述了几种常见分布式电源的并网控制方式,然后利用PSCAD/EMTDC软件搭建配电网模型,验证了分布式电源接入后对配电网故障电流方向和大小的影响,理论分析了分布式电源对配电网现有故障定位算法的影响。其次,对于任意类型分布式电源接入的配电网,本文提出了一种新的故障定位方案,该方案考虑了配电网中不对称分支线路和线路电容效应的影响,仅需要分别测量变电站出线端和分布式电源并网处故障前后的基频电压、电流值,即可准确完成故障定位。该方案分为两个步骤:第一,基于过渡电阻的性质,推导出一个通用的故障定位方程,可定位出多个故障位置点,该方法可避免先识别故障类型;第二,采用电压匹配的方法来祛除伪故障点的个数,即分别比较变电站及分布式电源测量电压与计算电压的差值。最后,利用PSCAD/EMTDC软件搭建含有两个固定风速发电机的改进IEEE34节点配电网系统作为仿真模型,来测试和评估本文所提故障定位方案的有效性。结果表明:在过渡电阻、故障距离和负载不确定性等因素影响下,该方案具有较好的故障定位准确性和鲁棒性,因此该方案有一定的实际应用价值。更多还原

【Abstract】 Distributed resource is the supplement and of centralized power grid.With the advantage of cleanness,environmental protection,sustainability and flexibility,the distributed resources obtain the rapid development and application in our country.However,because distributed resources are connected to distribution network in large quantities,the structure of distribution network will be changed;the direction of power flow is no longer single.Therefore,the problem that fault location for distribution network containing distributed resources will be more complicated,this paper mainly aims at above problem to carry on the analytic study.First of all,this paper introduces the current domestic and foreign research situation of fault location for distribution network,as well as the related concepts and the grid-connected standard requirements of distributed resources.Grid-connected control modes of several common distributed resources are described.Then,the distribution network model is built by using PSCAD/EMTDC simulation software to verify the influence of distributed resource on the direction and size of fault current.The impact of distributed resources on the existing fault location algorithm is analyzed in theory.Secondly,this paper presents a novel fault location scheme for distribution network in the presence of any possible distributed resource type.The unbalanced laterals and the capacitive effect of distribution line are considered.Only the fundamental values of voltages and currents measured before and after the fault at the substation and each DG unit bus are required to complete accurate fault location for the proposed method.The proposed scheme identifies the fault location using two steps.In the first step,based on the properties of fault resistance,a general fault location equation is derived,which can identify all possible fault location,this method overcomes the requirement of fault-type identification.In the second step,from the possible fault location,the exact fault location is then identified by matching the measured voltage at the substation bus and each DG unit bus with calculated ones and without using any additional devices.In the end,a modified IEEE 34-bus distribution system with two fixed-speed wind turbines was used to test and evaluate the proposed scheme by using PSCAD/EMTDC software.Test results verified the accuracy and robustness of the proposed scheme to identify the exact location under the effects of fault resistance,fault distance and load uncertainty.Thus,the proposed scheme is promising for practical applications.更多还原