【作者】 张慧颖；

【导师】 李斌； 张群华；

【作者基本信息】 天津大学 ， 电气工程（专业学位）， 2014， 硕士

【摘要】 目前,各国纷纷开始研究高效的、可靠的分布式发电技术。微电网就是在分布式发电基础上形成的一种新型的供电方式,但是随着分布式电源的接入,改变了传统意义上的潮流特性和故障特性,又给大电网的运行与维护提出了许多新的挑战。本文主要研究了微电网的故障暂态特性,研究重点集中于逆变型分布式电源故障暂态特征。逆变型分布式电源通过电力电子装置接入电网,在其并网运行过程中,当电力系统出现扰动,逆变电源将由先前的稳定运行状态经过一系列调整回复到原有稳定状态或者过渡到新的稳定状态。先后两个稳定状态之间的调整过程称之为故障暂态过程。并网逆变电源在故障暂态过程中受控于自身控制器,为了研究控制策略对并网逆变型分布式电源故障暂态特征的影响,首先建立了能够反映逆变器控制策略的逆变型分布式电源的详细模型;在此基础上,详细分析了控制器控制参数对逆变型分布式电源暂态响应的影响;针对对称性故障和非对称性故障情况,对逆变型分布式电源的故障暂态特征进行深入的分析。针对分布式电源多点接入的配电系统而形成的微电网,提出了一种基于暂态极性保护原理的集成保护新方案。暂态极性比较保护是运用小波变换提取故障暂态高频信号的某一频段信息作为故障判断的依据,通过比较暂态高频信号的极性,迅速准确判断出故障位置。将暂态极性比较保护原理应用于微电网集成保护方案中,以母线作为载体构建集成保护单元,利用本地故障信息和相邻保护单元故障信息对母线各出线以及线路两端信号的极性进行比较,从而对母线故障和线路故障进行判断。与此同时集成网络保护单元提取多点信息,对整体区域暂态信号极性进行综合比较,实现对故障的快速定位与隔离,为本地保护提供后备保护。更多还原

【Abstract】 Nowadays, the research on distributed generation seems to be efficient and dependable. The micro-grid is one of method which based on distributed generation. However, there seem to have new challenges in the operation of the grid since the introduction of distributed generation.This paper does an in-depth analysis and discussion about the fault transient characteristics of Micro-grid which focuses of the fault response of the Inverter-based distributed generators(IBDG).IBDG are integrated into distribution network through power electronic devices. In the process of parallel operation, when the power system disturbances occur, IBDG will adjust themselves through a series of operation to return to the original state or transit to a new stable state. Adjustment process between two stable states is called fault transient process. IBDG is controlled by its own controller in the transient process. In order to study the impact of the control strategy on the fault transient characteristics, a concrete model was set up including the inverter control strategy. Based on this model, the thorough analysis on the impact of the control parameters on the fault transient characteristics of IBDG was carried on. Then in-depth analysis on the fault transient characteristics of IBDG was carried on respectively in the cases of symmetry and asymmetry fault.A new integrated protection scheme based on transient polarity comparison is proposed for the multi-distributed generators distribution system. Transient polarity comparison theory is to extract the information of fault transient high frequency signal using wavelet transform, by comparing the polarity of which to judge the fault position quickly. In the new scheme, the transient polarity comparison protection is applied to the integrated protection, in which the integrated relay unit is built based on the busbars. The integrated relay unit compares the polarity of the lines out of the busbar to judge the busbar fault, and makes the judgement of line fault by comparing the polarity of the both ends of the line in use of the fault information and the information from the adjacent to busbar protection unit. Meanwhile integrated network protection unit extracts more information and makes a comprehensive comparison between the transient signal polarity to the whole area, to realize the fault isolation, rapid positioning and to provide backup protection for local protection.更多还原