摘    要
我国能源消耗主要依赖于传统化石能源，近年来随着社会经济的持续发展，我国化石能源危机和环境问题日趋严峻，改变我国能源产业结构，开发和利用新能源迫在眉睫。由于太阳能资源具有清洁无污染、安全可靠、运行经济以及取之不尽用之不竭等优点，决定了其在能源更替中具有不可取代的地位。以光伏发电技术为代表的新能源发电技术越来越受到国际社会的广泛关注。
在光伏发电系统中，分布式发电系统具有十分重要的地位，分布式电源为电网和本地负载提供能量。随着越来越多的分布式光伏发电系统应用于能源产业，许多潜在的电网保护问题逐渐引起了人们的重视，其中难点之一就是如何检测出孤岛效应。孤岛效应会导致电能质量严重受损、电气设备损害以及对运行检修工作者的安全造成威胁，因此应该避免孤岛现象的发生。通过相关反孤岛设备实时监测系统运行情况，在孤岛发生时检测出孤岛运行状态并触发孤岛保护装置，使光伏并网逆变器尽快与主电网切离以避免上述的危害。本文以三相光伏并网逆变器为研究对象，对系统中存在的孤岛效应检测问题进行研究，讨论了相关参数对孤岛检测盲区分布的影响，并根据现有反孤岛策略存在的不足，提出一种改进的基于无功功率扰动的孤岛检测算法。
本文阐述了孤岛效应的研究背景、成因以及危害，分析了当前孤岛检测技术的研究现状。基于逆变器恒功率控制策略对三相光伏并网逆变器进行建模，实现有功/无功功率的灵活控制，为后续所提孤岛检测算法的研究奠定基础。
本文研究分析了孤岛效应发生机理，对几种常见的孤岛检测方法如远程检测法、无源检测法和有源检测法进行对比分析。与此同时，本文介绍了孤岛检测盲区相关描述方法，并采用f 0norm Q C  描述法对常见反孤岛策略的盲区进行了描述，
分析了相关参数对盲区分布的影响，并基于所参与科研项目对现有盲区评估标准提出了几点改进建议。
基于对常见孤岛检测算法及其盲区的分析与研究，本文阐述了基于无功功率扰动反孤岛策略的优越性，并对其基本原理进行了分析。同时针对现有无功功率扰动孤岛检测方法在孤岛检测时效率较低以及对主电网电能质量影响较大两大方面的不足，提出了一种改进的基于无功功率扰动孤岛检测算法，并通过仿真及实验对本文所提孤岛检测算法进行验证。
关键词：光伏并网逆变器；孤岛检测；无功功率扰动；检测盲区
ABSTRACT
China's energy consumption mainly relies on traditional petrochemical fuels. Recently, the petrochemical energy crisis and environmental problems in our country have become more and more serious with the development of social economy. It is imminent to change our energy industrial structure and develop new energy sources. As solar energy resources have the advantages of being cl
ean, pollution-free, safe, reliable, economical, and inexhaustible, it has played an irreplaceable role in the renewable energy sources. The new energy power generation technologies represented by photovoltaic power generation technologies have received increasing attention from the international community.
In photovoltaic power generation systems, distributed power generation systems have a very important position. Distributed power supplies provide energy for the power grid and local loads. As more and more distributed photovoltaic power generation systems are used in the energy industry, many potential grid protection issues have gradually attracted people’s attention. One of the difficulties is that How to detect the islanding. The islanding can cause serious damage to power quality, damage to electrical equipment, and threats to the safety of operating personnel. Therefore, the occurrence of islanding should be avoided. The relevant anti-islanding equipment should be used to monitor the operation of the system in real time. When islanding occurs, the islanding state is detected and the islanding protection device is triggered so that the photovoltaic grid-connected inverter can be cut off from the main grid as soon as possible to avoid the aforementioned hazards.This paper takes the three-phase photovoltaic grid-connected inverter as the research object, studies the islanding detection existing in the system, discusses the influence of the relevant parameters on the distribution
of Non-Detection Zone, and according to the existing deficiencies of the anti-islanding strategies, An improved islanding detection algorithm based on reactive power disturbance is proposed.
This paper expounds the research background, cause and harm of islanding, and analyzes the current research status of islanding detection technology. The three-phase photovoltaic grid-connected inverter is modeled based on the constant power control strategy of the inverter to achieve flexible control of active/reactive power, which lays the foundation for the subsequent research on islanding detection algorithms.
重庆大学硕士学位论文
A comprehensive study of the mechanism of islanding, comparative analysis of several common islanding detection methods such as remote detection, passive detection and active detection methods. At the same time, the description method of non-detection zone is introduced. The non-detection zone of common anti-islanding strategy is described by Q f0×C norm description method. The influence of related parameters on the distribution of non-detection zone is analyzed. Based on the participating scientific research projects, several improvements are proposed for the existing assessment criteria for non-detection zone.
Based on the analysis and research of common islanding detection algorithms and their non-detection zone, the advantages of anti-islanding strategies based on reactive power disturbances are described, and the basic principles are analyzed. Aiming at the shortcomings of the existing reactive power disturbance islanding detection methods, such as low efficiency in islanding detection and large impact on power quality, a novel islanding detection method based on reactive power disturbance is proposed and simulated. And the experiment verified the islanding detection algorithm proposed in this paper.
Keywords: PV grid-connected inverter; Islanding Detection; Reactive Power Disturbance; Non-detection Zone.
IV
目    录
目    录
中文摘要 .......................................................................................................................................... I  英文摘要 ....................................................................................................................................... III 1 绪  论 .. (1)
1.1 课题研究背景与意义 (1)
1.2 孤岛效应的定义及危害 (2)
1.3 孤岛检测技术研究现状 (3)
1.4 本文主要研究内容 ................................................................................................................... 4 2 基于三相并网逆变器的光伏发电系统建模 (7)
2.1 光伏并网逆变器拓扑结构 (7)
2.1.1 隔离型光伏并网逆变器 (7)
2.1.2 非隔离型光伏并网逆变器 (9)
2.2 三相光伏并网逆变器建模 (10)
2.2.1 三相光伏并网逆变器主电路建模 (10)
2.2.2 三相光伏并网逆变器控制器设计 (12)
2.3 仿真验证 (18)
2.4 本章小结 ................................................................................................................................. 21 3 孤岛检测算法分析与盲区描述 (23)
3.1 孤岛检测技术概述 (23)
3.1.1 孤岛效应发生机理 (23)
3.1.2 孤岛效应检测标准 (25)
3.2 无源孤岛检测方法 (27)
3.2.1 过/欠电压、过/欠频率孤岛检测法 (27)
3.2.2 电压谐波孤岛检测法 (30)
3.2.3 相位突变孤岛检测法 (30)
3.3 有源孤岛检测方法 (31)
3.3.1 有源频率偏移法 (32)
3.3.2 有功电流扰动法 (35)
3.4 基于f 0norm Q C  坐标系的孤岛检测盲区描述方法 (36)
3.5 关于孤岛检测盲区评估标准的改进建议 (44)
3.6 本章小结 ................................................................................................................................. 44 4 无功功率扰动孤岛检测算法的分析与改进 . (47)
重庆大学硕士学位论文
4.1无功功率扰动孤岛检测算法原理 (47)
4.2一种改进的无功功率扰动孤岛检测算法 (50)
4.3改进型无功功率扰动孤岛检测算法对电能质量影响的分析 (54)
4.4改进型无功功率扰动孤岛检测算法盲区分析 (54)
4.5仿真及实验验证 (56)
4.6本章小结 (62)
5 总结与展望 (65)
5.1总结 (65)
5.2展望 (65)
reactive to致谢 (67)
参考文献 (69)
附录 (73)
A作者在攻读硕士学位期间发表的论文 (73)
B作者在攻读硕士学位期间参与的科研项目 (73)
C作者在攻读硕士学位期间参与的专业实践 (73)