【作者】 翁国庆；

【导师】 曹一家； 张有兵；

【作者基本信息】 浙江工业大学 ， 控制理论与控制工程， 2010， 博士

【摘要】 网络化、信息化、标准化和智能化已成为电能质量监测系统(PQMS)的必然发展趋势,而嵌入式系统与网络通信技术的快速发展为电能质量网络化监测方案的提出创造了机遇。网络化PQMS系统可以实现多点、连续的在线监测,中心工作站汇集丰富的全局性信息并配置各种智能诊断软件,可实现趋势判断、概率统计、综合评价、扰动事件辨识、Web服务等高级功能,为配电网络提供先进的电能质量监督和服务手段,具有传统单测点监测方案无法比拟的优势。网络化PQMS系统是电能质量监测研究的新领域。本论文首次概括了网络化PQMS系统研究和应用推广过程中存在的功能算法、技术实现及经济成本等多方面的挑战,并对其中若干关键技术进行了深入的研究,主要包括:动态电能质量扰动辨识、区域电能质量综合评价、扰动事件源自动定位以及低成本、高性能的通信网络构建方案等。本论文的创新成果主要包括以下几个方面:1.提出一种由高速配电线载波通信(DLCC)网络、电能质量工作站及数量众多的电能质量监测终端(PQM)组成的网络化PQMS系统构建方案,并对其结构、功能进行了详细的分析、设计与规划。2.基于“扰动生成→特征提取→模式分类→结果分析”的思路,提出一种基于广义S变换和多级支持向量机(SVMs)的动态电能质量扰动辨识算法。首先利用广义S变换将动态电能质量扰动信号变换到相空间中,定义多种特征曲线并据此提取特征量,然后构建、训练了一种多级SVMs分类决策树结构的模式分类器。仿真结果表明,该算法对瞬时性、随机性及非平稳性的动态电能质量扰动具有灵活、快速、准确的辨识能力。3.基于物元和可拓学理论,提出一种由单测点到各等级区域的电能质量多级可拓综合评价体系。单测点综合评价中,提出一种新的基于关联度的时变客观赋权法,并对传统的主观赋权法进行了一致性判定的改进。区域综合评价中,建立了一种以所属子区域的电压等级、负荷容量、用户数、用户重要性、用户敏感度及质量性能为特征项的综合评价指标体系,并据此分别设计了其主、客观赋权算法。案例分析验证了该区域电能质量多级可拓综合评价方法的有效性。4.提出了一种基于链表和矩阵算法的配电网电能质量扰动事件源三级自动定位算法。I级定位,实现基于链表法的扰动馈线子区域快速预判;II级定位,基于系统监测覆盖矩阵和方向信息矩阵实现扰动事件源的初步判定;III级定位,定义“虚拟PQM”,基于扩展矩阵算法实现扰动事件源的准确定位。研究表明,该算法具有简洁直观、计算量小、快速、精确、适于计算机编程实现等特点。5.为降低网络化PQMS系统的构建成本,提出采用一种基于OFDM技术的高速DLCC网络方案。首先,对系统中各PQM的通信速率需求及该DLCC网络通信速率性能进行了论证;其次,提出了一种改进型的DLCC信道衰减特性分析方法,并对系统在信道特性、基带调制方式及信号输出功率三个因素影响下的通信质量性能进行了仿真研究。最后,提出了一种基于信号广播及传输矩阵的DLCC网络通信链路动态拓扑结构的确定方法,并以中继跳数最小化为目标实现了DLCC网络的路由优化。仿真和分析验证了该通信网络方案的可行性,能够满足网络化PQMS系统的通信需求。更多还原

【Abstract】 It is an inevitable future trend of power quality monitoring system (PQMS) to realize network, informatization, standardization and intelligent. Rapid development of embedded system and network communication technology creates an opportunity for putting forward the network monitoring scheme of power quality, which can realize continuous on-line monitoring of multiple-spots. With abundant and overall information centralized and various intelligent diagnostic softwares configured, those advanced functions such as tendency judgment, probability statistic, comprehensive evaluation, disturbance event identification and Web services can be achieved in the center workstation. The network PQMS provides advanced supervision and service methods for power quality in distribution network, with increasing incomparable advantages compared to the traditional single-point monitoring scheme.The network PQMS is a new research field of power quality monitoring. This paper summarizes multifaceted challenges for the first time, such as function algorithms, technical realization, economical costs, etc., which are existing in the process of research and application extending of the network PQMS. Several key technologies have been in-depth studied, mainly including disturbance identification of dynamic power quality, comprehensive evaluation of regional power quality, automatic location of disturbance event source, construction of low-cost and high-performance communications network, etc. The creative works of this paper mainly include the following aspects:1.A new system construction scheme of the network PQMS is proposed, which is composed by high-speed distribution line carrier communication (DLCC) network, power quality workstation and a large number of power quality monitors (PQM). Then, structure and functions of the network PQMS are carried out a detailed analysis, design and planning.2.According to the idea of“disturbances generation→characteristics extraction→pattern classification→result analysis”, an identification algorithm for dynamic power quality disturbances (PQD) based on Generalized S-transform (GST) and multi-level support vector machines (SVMs) is presented. The PQD signals are transformed into phase space by GST firstly, then, multiple characteristic curves are defined and characteristics are extracted. After that, a pattern classifier is constructed and trained, with the structure of classification decision tree based on multi-level SVMs. Simulation results show that, for dynamic PQD signals with the features such as instantaneity, randomness and nonstationarity, the algorithm has the ability to identify them flexibly, quickly and accurately.3.Based on matter-element and extension theory, a multi-stage extension method is suggested to realize the comprehensive evaluation (CE) of power quality from single-point to various levels of regional. In single-point CE process, a new objective weighting method with time-varying characteristic based on correlation degree is designed, and the traditional subjective weighting method is been improved for its difficulties to determine consistency. In regional CE process, a new index system is established, which’s characteristic items include voltage level, load capacity, number of users, importance of the user, user sensitivity, quality performance of the subregions. Based on this, the subjective and objective weighting algorithms for regional CE are developed respectively. Case studies validate the effectiveness of the multi-stage CE method of power quality.4.The location problem of PQD event source in distribution network is explored, and one kind of three-level automatic location algorithm basing on linked-list and matrix algorithm is put forward. Firstly, rapid predict for the feeder sub-regional with PQD is achieved using linked-list method. Secondly, preliminary judgment for PQD event source is realized according to the monitoring coverage matrix and direction information matrix. Thirdly, after the concept of virtual PQM defined, accurate location for PQD event source is implemented with extension matrix algorithm. It shows that the proposed algorithm has many advantages, such as simple and intuitive, low computational complexity, fast and accurate, suitable for computer programming, and etc.5.To reduce construction costs of the network PQMS, a type of high-speed DLCC network scheme with the OFDM technology is adopted. After analyzing the requirement of communication rate to each PQM, the performance of communication rate of the DLCC network is discussed. Then, with the improved analysis method for channel attenuation and the simulation model of the DLCC system based on the OFDM technology, the performance of communication quality is researched, under the influence of three factors including channel characterization, base-band modulation and signal output power. By combining with means of signal broadcasting and transfer matrix, communication link dynamic topology of the DLCC network can be determined. Aiming to minimization of the relay hops, a novel routing optimization method for the DLCC network is proposed. Simulation and analysis verified the feasibility of the DLCC network scheme, and it is able to meet the communication requirements of the network PQMS.更多还原