微电网的故障特性分析及保护策略研究

发布时间：2018-05-31 02:34

本文选题：微电网 + 故障特性　；参考：《兰州交通大学》2017年硕士论文

【摘要】：目前,MG(Micro-Grid,微电网)技术已经成为整合分布式新能源发电的一个有效手段,促进了新能源的开发和利用,一定程度上缓解了能源压力。但是,MG供配电系统的结构有别于传统的配电网,从而可能导致传统保护方法不再适用于MG系统中。因此对MG的故障特性及保护策略等问题进行研究是保障MG安全、可靠运行的基础,对MG技术的发展具有重要的理论研究价值和工程指导意义。论文主要研究内容如下:(1)论文在分析MG系统结构和运行特点的基础上,阐述了MG中各类微电源即DG(Distributed Generation,分布式发电)单元的并网运行方式以及控制方式,重点分析IBDG(Inverter-Based Distributed Generation,逆变型分布式电源)在逆变器不同保护方式下的故障等效模型,在此基础上利用PSCAD仿真软件建立了低压交流MG运行模型,仿真分析了电力系统常见故障发生时,MG在并/离网不同运行状态下的故障输出特性。(2)在结合MG故障特性的基础上对MG保护特性进行了分析,研究了MG故障穿越运行条件下联络线的保护方案,着重分析DG接入位置以及容量的变化对MG保护的影响,同时对比分析MG不同运行方式下故障电流的幅值变化对保护的影响。在此基础上,研究基于集中式决策结构的通信系统的MG孤岛运行保护方案,该方案以IED(Intelligent Electronic Device,智能电子装备)为保护中心的监控以及通信元件,采用改进的基于网基结构的矩阵故障定位与隔离算法实现MG的保护,该算法以过电流信息为启动条件,以故障电流方向信息为故障判别条件,算例分析表明了该算法不仅能够解决MG系统中常规线路故障的定位与隔离问题,同时亦能实现孤岛运行的MG中馈线首、末端故障、多重故障以及故障信息缺失等情况下的故障定位与隔离功能。(3)针对MG并/离网同一保护策略的问题进行研究,以基于分布式决策结构的IED通信系统为框架,借鉴纵联差动保护的动作原理,通过定义各IED的关联系数、故障时的方向系数以及故障判据实现各IED的快速I段主保护以及后备保护功能,同时,考虑到通信中断的情况,分析设计了MG通信中断下基于线路始端过电流保护的故障隔离策略。算例分析表明了基于分布式决策结构的MG并/离网同一保护策略不仅能够完成对故障线路以及故障母线的隔离功能,亦能够解决IED或断路器拒动情况下的故障隔离问题,同时,算例验证了通信中断下MG故障隔离策略的有效性及可靠性。
[Abstract]:At present, MG (Micro-Grid) technology has become an effective means to integrate distributed new energy power generation. It has promoted the development and utilization of new energy, alleviated the energy pressure to some extent. However, the structure of MG power supply and distribution system is different from the traditional distribution network, which may lead to the traditional protection method no longer applicable to the MG system. Therefore, research on the fault characteristics and protection strategy of MG is the basis of ensuring the security and reliable operation of MG. It has important theoretical research value and engineering guiding significance for the development of MG technology. The main contents of this paper are as follows: (1) on the basis of analyzing the structure and running characteristics of the MG system, the paper expounds the various kinds of micro power sources in MG The parallel operation mode and control mode of DG (Distributed Generation, distributed generation) unit are used to analyze the fault equivalent model of IBDG (Inverter-Based Distributed Generation, inverter type distributed power) under different protection modes of inverters. On this basis, a low voltage AC MG running model is established by using PSCAD simulation software. The fault output characteristics of MG in the parallel / off network running state are simulated and analyzed. (2) the protection characteristics of MG are analyzed on the basis of MG fault characteristics, and the protection scheme of the connection line is studied under the condition of MG fault crossing operation. It emphasizes the analysis of the location of DG access and the change of capacity to MG protection. At the same time, the influence of the amplitude change of the fault current in different operation modes of MG on protection is compared and analyzed. On this basis, the MG island operation protection scheme of the communication system based on centralized decision structure is studied. The scheme uses the IED (Intelligent Electronic Device, intelligent electronic equipment) as the monitoring and communication element of the protection center. An improved matrix fault location and isolation algorithm based on the network based structure is used to protect the MG. The algorithm uses the overcurrent information as the starting condition and the fault current direction information as the fault discrimination condition. The calculation example shows that the algorithm can not only solve the problem of location and isolation of regular line faults in the MG system, but also can be used for the fault location and isolation. To realize the fault location and isolation function of the MG feeder head, terminal fault, multiple fault and lack of fault information. (3) the problem of the same protection strategy for MG and / off network is studied. The IED communication system based on distributed decision structure is taken as frame, and the action principle of longitudinal differential protection is used for reference. The correlation coefficient of each IED, the direction coefficient of the fault and the fault criterion to realize the main protection and backup protection of the fast I segment of each IED. Meanwhile, considering the interruption of the communication, the fault isolation strategy based on the overcurrent protection based on the starting end of the line is analyzed and designed. The example analysis shows that the distributed decision structure is based on the distributed decision structure. The same protection strategy of MG and / off network can not only complete the isolation of fault lines and fault buses, but also solve the problem of fault isolation in the case of IED or circuit breaker rejection. At the same time, the calculation example validates the validity and reliability of the MG fault isolation strategy under the communication interruption.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727

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