多逆变器并联运行微网孤岛检测方法的研究
发布时间：2018-09-19 07:53
【摘要】：近年来,随着一次能源的使用量日益加剧、能源的逐渐枯竭以及环境问题的日益恶化与凸显,越来越多的清洁绿色可在再生能源逐渐显露头角,被越来越多的广泛应用接入电网。在众多的新型绿色能源中,光伏发电占了较大的比重,对于一个与电网互联的以光伏发电为主体的分布式发电系统,针对它的安全性与运行可靠性的要求及越来越高,那么针对于光伏发电系统的孤岛检测环节就显得尤为重要,这也是电网与分布式发电系统互联工作的最基本保障。同时,随着光伏发电系统所接入的微电网规模越来越大,单台逆变器的可承受功率容量已不满足实际需要,多台逆变器同时并联工作的情况已然越来越多,因此针对于多机系统的孤岛检测也变得有实际工程应用的价值。首先,本文从孤岛效应的定义出发,阐述了它的发生原理及危害,探讨了孤岛效应发生的条件,介绍了国内外通用的孤岛检测标准,进而引出孤岛检测的方法。主要有基于通信侧和本地侧两种,本地侧检测方法又分为被动式检测和主动式检测,对这些方法的详细介绍后比较出优缺点和适用范围,同时介绍了描述孤岛检测盲区的四种坐标模型。从主动式检测法中选取常用的主动移频式检测法和主动移相式检测法作为本文的研究重点。其次,分别对主动移频式和主动移相式两种方法作了深入探讨,阐述其检测原理,对各自的参数设计方案都分别进行了仿真验证。对于主动移频式探究了截断系数选择与电流畸变程度之间的关系;针对于由滑膜频率偏移法引申而来的自动移相法的相位表达式加以简化,并对其反馈系数通过引入模糊控制加以优化和改进,并重新搭建模型验证了改进算法的可行性。最后,由于越来越多的光伏发电系统接入电网,多台逆变器的并联运行是大势所趋。本文以两台逆变器作为讨论对象,设计了四种逆变器组合方法:被动式与主动移频式结合、主动移频与带正反馈的主动移频相结合、主动移频与主动移相式结合和两台主动移相式在带有频率检测误差时的并联运行。分别讨论了他们的相互内在的联系和影响、各自的检测盲区并在各种参数设置和盲区内外分别加以仿真验证,以探究各种因素对多台逆变器并联运行孤岛检测性能的影响
[Abstract]:In recent years, with the increasing use of primary energy, the gradual depletion of energy and the worsening and highlighting of environmental problems, more and more clean green energy can be gradually revealed in renewable energy. It is more and more widely used to connect to the power grid. Among many new green energy sources, photovoltaic power generation accounts for a large proportion. For a distributed power generation system which is connected with the power grid, the security and operation reliability of the distributed generation system is becoming higher and higher. So the detection of isolated islands for photovoltaic power generation system is particularly important, which is the most basic guarantee of interconnection between power grid and distributed generation system. At the same time, with the increasing scale of microgrid connected to photovoltaic power generation system, the tolerable power capacity of a single inverter is no longer satisfied with the actual needs, and there are more and more cases of parallel operation of multiple inverters at the same time. Therefore, the islanding detection for multi-computer systems has become of practical engineering value. Firstly, from the definition of islanding effect, this paper expounds its occurrence principle and harm, discusses the conditions for the occurrence of islanding effect, introduces the common detection standards of islanding at home and abroad, and then leads to the method of islanding detection. There are two main methods based on the communication side and local side. The local side detection methods are divided into passive detection and active detection. After the detailed introduction of these methods, the advantages and disadvantages and the scope of application are compared. At the same time, four coordinate models are introduced to describe the blind area of isolated island detection. The active frequency shift detection and active phase shift detection are selected as the focus of this paper. Secondly, the two methods of active frequency shift and active phase shift are discussed in detail, the detection principle is expounded, and the design schemes of each parameter are verified by simulation. The relationship between the selection of truncation coefficient and the degree of current distortion is explored, and the phase expression of the automatic phase-shifting method derived from the synovial frequency shift method is simplified. The feedback coefficient is optimized and improved by introducing fuzzy control, and the feasibility of the improved algorithm is verified by reconstructing the model. Finally, because more and more photovoltaic power systems are connected to the power grid, the parallel operation of multiple inverters is the trend of the times. In this paper, two inverters are taken as the object of discussion. Four kinds of inverter combination methods are designed: passive and active frequency shifting, active frequency shifting and active frequency shifting with positive feedback. The combination of active frequency shift and active phase shift and the parallel operation of two active phase shifters with frequency detection error. Their internal relationship and influence are discussed respectively, and their blind areas are tested and simulated in various parameter settings and inside and outside blind areas respectively, in order to explore the influence of various factors on the detection performance of parallel operation isolated island of multiple inverters.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727;TM464
[Abstract]:In recent years, with the increasing use of primary energy, the gradual depletion of energy and the worsening and highlighting of environmental problems, more and more clean green energy can be gradually revealed in renewable energy. It is more and more widely used to connect to the power grid. Among many new green energy sources, photovoltaic power generation accounts for a large proportion. For a distributed power generation system which is connected with the power grid, the security and operation reliability of the distributed generation system is becoming higher and higher. So the detection of isolated islands for photovoltaic power generation system is particularly important, which is the most basic guarantee of interconnection between power grid and distributed generation system. At the same time, with the increasing scale of microgrid connected to photovoltaic power generation system, the tolerable power capacity of a single inverter is no longer satisfied with the actual needs, and there are more and more cases of parallel operation of multiple inverters at the same time. Therefore, the islanding detection for multi-computer systems has become of practical engineering value. Firstly, from the definition of islanding effect, this paper expounds its occurrence principle and harm, discusses the conditions for the occurrence of islanding effect, introduces the common detection standards of islanding at home and abroad, and then leads to the method of islanding detection. There are two main methods based on the communication side and local side. The local side detection methods are divided into passive detection and active detection. After the detailed introduction of these methods, the advantages and disadvantages and the scope of application are compared. At the same time, four coordinate models are introduced to describe the blind area of isolated island detection. The active frequency shift detection and active phase shift detection are selected as the focus of this paper. Secondly, the two methods of active frequency shift and active phase shift are discussed in detail, the detection principle is expounded, and the design schemes of each parameter are verified by simulation. The relationship between the selection of truncation coefficient and the degree of current distortion is explored, and the phase expression of the automatic phase-shifting method derived from the synovial frequency shift method is simplified. The feedback coefficient is optimized and improved by introducing fuzzy control, and the feasibility of the improved algorithm is verified by reconstructing the model. Finally, because more and more photovoltaic power systems are connected to the power grid, the parallel operation of multiple inverters is the trend of the times. In this paper, two inverters are taken as the object of discussion. Four kinds of inverter combination methods are designed: passive and active frequency shifting, active frequency shifting and active frequency shifting with positive feedback. The combination of active frequency shift and active phase shift and the parallel operation of two active phase shifters with frequency detection error. Their internal relationship and influence are discussed respectively, and their blind areas are tested and simulated in various parameter settings and inside and outside blind areas respectively, in order to explore the influence of various factors on the detection performance of parallel operation isolated island of multiple inverters.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727;TM464
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