含分布式发电的配电系统保护研究

发布时间：2018-05-08 09:33

本文选题：分布式发电 + 配电网　；参考：《西南交通大学》2014年硕士论文

【摘要】：在能源开发、环境保护和完善电网建设的多重需求之下,以可再生能源为主的分布式发电技术在近些年来受到广泛关注,得到飞速发展。分布式发电(Distributed Generation,简称DG)一般接入中低压配电网,而我国中低压配电系统一般是非直接接地系统,为单电源辐射型网络,DG的接入使配电网的网络结构发生了根本变化,变为双电源甚至多电源网络,潮流不再单向地从变电站母线流向负荷,这使得原有的保护系统,包括定值、保护算法、保护之间的配合、以及保护与重合闸之间的配合关系都可能受到影响。分布式发电接入对配电网继电保护带来的影响,使得传统的故障检测方法和继电保护模式难以满足电网安全运行需要,需要在研究分布式发电的接入对配电网影响的基础上对配电网的保护策略进行研究。本文首先介绍了分布式发电的主要类型及其运行特性,并对通过电力电子装置输出电能的逆变型DG的控制方式进行了概述,在此基础上对逆变型分布式发电的并网模型进行了等效建模,从而为研究DG接入对传统配电网保护的影响奠定了基础。在分析DG接入对配电网保护系统的影响时,对DG接入不同容量及不同位置对配电网线路保护产生的影响分别进行了分析。首先讨论了DG接入位置不变而容量变化时对配电网各线路保护的影响,其次分析了DG接入位置不同而容量不变时对传统配电网三段式电流保护及重合闸的影响,并进行了仿真验证,最后理论推导了DG接入不同位置对距离保护的影响。分析说明DG接入配电网改变了配电网原有的拓扑结构,发生故障时,DG的存在有可能导致配电网原有保护失去可靠性。在此基础上,提出将分区方向纵联保护与过电流保护相配合的保护新方案应用于含DG的配电网,根据DG接入的位置对被保护线路进行区域划分,在DG接入点靠近系统侧的区域配置方向纵联电流保护作为主保护,而原配电线路的过电流保护则作为后备保护,从而实现可靠快速切除故障。最后提出将距离保护用于含DG的配电网,分析了其优势与存在的问题,并进行算例分析,说明DG接入对距离保护整定值的影响。将分布决策广域保护模式应用到含DG的配电网的保护中,从含DG的配电网网络结构出发对网络进行编号和区域划分,根据故障区段电流的特点通过故障一次和故障二次定位,准确定位并切除故障实现对配电网的保护。以含DG的配电系统为例进行算例分析,说明了该方案的有效性及对DG投切的自适应性,最后对该方案所使用的两个判据进行了仿真验证。
[Abstract]:Under the multiple demands of energy development, environmental protection and the improvement of power grid construction, the distributed generation technology, which is mainly renewable energy, has been widely concerned and developed rapidly in recent years. The distributed generation (DG) is generally connected to the medium and low voltage distribution network, while the medium and low voltage distribution system in China is generally non-directly grounded system. The network structure of the distribution network has been fundamentally changed by the access of DG to the single source radiation network. The power flow no longer flows unidirectionally from the substation bus to the load, which makes the original protection system, including the fixed value, the protection algorithm, the cooperation between the protection. The relationship between protection and reclosing may be affected. The influence of distributed generation access on relay protection in distribution network makes it difficult for traditional fault detection methods and relay protection modes to meet the needs of grid safety operation. On the basis of studying the influence of distributed generation access on distribution network, the protection strategy of distribution network should be studied. In this paper, the main types and operation characteristics of distributed generation are introduced, and the control mode of inverter DG which outputs electric energy through power electronic devices is summarized. On this basis, the equivalent modeling of the grid-connected model of inverter distributed generation is carried out, which lays a foundation for the study of the influence of DG access on the traditional distribution network protection. When the influence of DG access on distribution network protection system is analyzed, the influence of DG access capacity and location on distribution network line protection is analyzed respectively. In this paper, the influence of DG access position and capacity change on the protection of distribution network is discussed. Secondly, the influence of DG access location and capacity invariant on the three-section current protection and reclosing of traditional distribution network is analyzed. Finally, the influence of DG access position on distance protection is deduced theoretically. The analysis shows that DG access to the distribution network changes the original topology of the distribution network, and the existence of DG in the event of failure may lead to the loss of reliability of the original protection of the distribution network. On this basis, a new protection scheme, which is combined with zonal directional longitudinal protection and over-current protection, is proposed for distribution network with DG, and the protected lines are divided according to the location of DG access. In the area near the system side of the DG access point, the directional longitudinal current protection is used as the main protection, while the over-current protection of the original distribution line is used as the backup protection, so that the fault can be removed reliably and quickly. In the end, the distance protection is applied to the distribution network with DG. The advantages and problems are analyzed, and an example is given to illustrate the influence of DG access on the setting of distance protection. The distributed decision wide area protection mode is applied to the protection of distribution network with DG. The network number and area are divided from the network structure of distribution network with DG. According to the characteristics of fault section current, the fault primary and secondary fault location are carried out. Accurate location and fault removal to achieve distribution network protection. Taking the distribution system with DG as an example, the effectiveness of the scheme and its adaptability to DG switching are illustrated. Finally, the two criteria used in the scheme are simulated and verified.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM77

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