【作者】 韩奕；

【导师】 胡学浩； 张东霞；

【作者基本信息】 中国电力科学研究院 ， 电力系统及其自动化， 2011， 博士

【摘要】 分布式发电和微网具有资源和环境友好,供电灵活、可靠等优点,在集中式发电和大电网的基础上发展分布式发电,已经成为国内外电力系统发展的必然趋势。分布式发电的接入改变了配电网的结构,使得配电系统从单电源辐射式网络变为多端有源网络,潮流不再单向地从变电站母线流向负荷。配电网的变化将对其原有保护装置产生影响。分布式电源产生的故障电流,可能使得配电线路故障电流的大小和方向发生变化,从而使得保护范围发生变化,而导致保护装置误动或拒动。研究改进配电网保护系统以适应分布式电源或微网接入,对配电网安全可靠运行具有重要的意义。本文主要针对分布式电源和微网带来的电力系统保护问题进行研究。利用可再生能源发电的分布式电源和微网中的微电源,通常需要通过电力电子接口将其发出的电能转换成与电网同频的工频交流电。经电力电子接口电源的故障特征与传统同步发电机有很大不同,论文通过研究经逆变器接口分布式电源与微网的数学和仿真模型,分析当线路中发生各种短路故障时,电源出口以及故障线路的故障特征；进而分析分布式电源及微网并网对原有配电网继电保护装置的影响；然后研究适用于分布式电源及微网接入的配电网继电保护改进方法和新型配电网保护方法。微网与传统电网故障特征的差异,使得传统基于大故障电流的保护算法不再适用。在分析微网内故障线路故障特征的基础上,提出适用于微网的保护算法。论文的主要研究内容如下：(1)在经逆变器接口分布式电源(IIDG)数学模型的基础上,通过DIgSILENT/PowerFactory软件建立其仿真模型,分析恒功率、恒压恒频两种常用控制方式下,经逆变器接口分布式电源出线的故障特征。(2)在微网数学模型的基础上,通过DIgSILENT/PowerFactory软件平台,建立微网的仿真模型,分析并网和孤岛两种运行模式下,微网内故障线路在各种故障情况下的故障特征。(3)在分布式电源或微网并网运行对配电网原有继电保护装置影响的研究基础上,对配电网原有保护设置进行改进,提出了对分布式电源产生故障电流进行补偿的配电网新型自适应电流保护算法,并通过仿真验证了该算法的有效性。(4)在智能电网建设的背景下,在充分利用通信设备的基础上,提出了基于多Agent技术的配电网保护系统,包括多Agent系统的逻辑框架和通信架构,基于多Agent技术的主保护算法,保护协调策略,以及孤岛保护方案,并通过仿真验证了该方案的可行性。(5)在研究微网故障特征的基础上,提出了改进复小波滤波算法；利用电流相位作为判据,采用自适应算法,提出了微网在并网和孤岛运行两种模式下均适用的自适应电流相位比较式纵联保护算法,并通过仿真验证了该算法的有效性。更多还原

【Abstract】 Distributed generation (DG) and microgrid have the advantages of resources and environment friendliness, flexibile and reliable power supply. With the development of bulk power system, developing distributed generation has become an inevitable trend in power systems home and abroad. Grid connected distributed generation changes the structure of distribution network, which makes the distribution system from single supply radial network to multi-source network. The power flow is no longer one way flowing from substation to the load. The changes in the distribution network have impacts on the existing protection as well. The fault current induced by DG changes the fault current magnitude and direction on distribution line, and the scope of protection, causing malfunction, misoperation or failure to operate of protective relay. Study on improving the protection system to adapt new distribution network with grid-connected distributed generations is significant to the safe and reliable operation of distribution network. This dissertation focuses on the protection issues of distribution network with distributed generations connected.Distributed generation and micro-generation in microgrid are usually renewable energy sourced power generation, which need power electronic device as interface to converter the power produced to that with the same frequency in grid. The fault characteristics of the inverter interfaced DG are different from that of traditional synchronous generators. The dissertation studies the mathematic and simulation model of inverter interfaced DG and microgrid, analyzes the fault features of the DG outlet and fault line when a variety of short circuit fault occurs in the power line, analyzes the impact on the traditional protection relays of distribution network, then studies the improvement of the protection in distribution network to accommodate DG’s integration. The fault characteristics differences between the microgrid and traditional power grid make the traditional protection algorithm based on large fault current no longer suitable. On the basis of analyzing the fault features of fault line in microgrid, a new protection algorithm for microgrid is proposed. The main aspects of the dissertation are listed as follows:(1) On the basis of mathematical model of inverter interfaced distributed generation (IIDG), the simulation model is established through DIgSILENT /PowerFactory software. The fault characteristics of inverter interfaced distributed generation in two common control modes:PQ control and V/f control are analysed.(2) On the basis of mathematical model of microgrid, a simulation model of microgrid is built on the DIgSILENT/PowerFactory software platform. The fault feature in different fault conditions in microgrid lines is analysed, when microgrid operating in stand-alone or grid-connected mode.(3) The impacts of the integration of DG and microgrid on the protection performace of distribution networks are studied. An adaptive current protection algorithm for improving the original protection settings in distribution networks is proposed, which offsets the impact on fault current caused by DGs using compensating factors. The effectiveness of the algorithm is verified by simulation.(4) A new distribution network protection scheme based on multi-agent technology is proposed, including the logical framework and communication architecture of multi-agent system, the main protection algorithm, protection coordination strategy and islanding protection scheme, etc. The feasibility of the scheme is verified by simulation.(5) An improved wavelet algorithm for digital filtering is proposed based on the fault characteristics in microgrid. By using the current phase as criterion, an adaptive current phase comparison pilot protection algorithm is proposed, in which adaptive algorithm is applied. The algorithm is suitable when microgrid is operating in stand-alone and grid-connected modes. The effectiveness of the algorithm is verified by simulation.更多还原