电网生存性评估及扰动源定位方法研究

发布时间：2018-08-22 14:06

【摘要】：电网作为保障现代社会经济发展和安全稳定的重要基础设施,其安全问题一直受到高度的关注。近年来大停电事故的多次发生揭示了电网本身存在固有的安全隐患,极端自然灾害暴露了电网应对恶劣外部环境时的脆弱性,电网在蓄意攻击场景下的应对能力应当引起警惕。电网在“内忧外患”环境下的生存能力值得深思。现有的电网生存性评估或脆弱性评估理论已取得了许多成果但仍存在一些不完善的地方,如单纯从电网结构的角度考虑电网脆弱性而忽视了电网运行方式的影响,缺乏对于电网结构均衡性和脆弱性之间相互关联的深入分析和评价,少有从内因和外因相结合的角度对于电网正常运行方式下和电网扰动状态下的电网生存性的综合评判。为此,本文从电网完成基本电能传输任务能力的角度围绕电网在正常运行方式下和扰动状态下已存在和潜在的生存问题展开研究,建立了电网生存性评估指标体系评估方法及扰动源定位方法。完善了电网生存性评估的理论体系,为电网安全性评估提供了一个新的角度。所做的工作和所取得的主要成果归纳如下：提出了基于潮流追踪方法的电能传输路径解析方法,能够透过电网潮流的表面深入分析电能流动的深层特性,得到全网的“发电机-负荷”节点之间的所有电能传输路径,并基于电能传输路径分析定义了电气距离,克服了只依赖网络结构定义电气距离方法的缺陷,能够更全面地反映电网的电能传输特性。在此基础上构建了能够反映电网电能传输效率的畅通性评估指标及方法,并能够辨识出对电网电能传输中起枢纽作用的重要元件。考虑了电网关键节点与关键支路在空间尺度上的分布特征对也电网脆弱性的影响,提出了考虑多源扰动及电网自身结构均衡特性的电网脆弱性评估指标与评估方法。通过分析电网节点和支路在电能传输作用方面的分布差异提出电网结构的均衡度指标,定义了节点之间的空间距离和支路之间的空间距离,并提出了关键节点的空间分布均衡度和关键支路的空间分布均衡度。综合考虑元件失效对于电网整体传输性能的影响建立了电网对于关键元件的依赖度指标。分析了电网在随机失效和蓄意攻击2种模式下的脆弱性。建立了综合考虑电网畅通性、均衡性和脆弱性的电网生存性评估指标体系及评估方法研究,提出了基于层次分析法和改进灰色关联度法的生存性指标权重分层优选方法,将电网生存性各项指标综合形成一个有机整体。提出了基于电网生存性评估的电网规划方案方法。基于典型实际电网算例构建了4个规划方案,计算了各个规划方案的生存性各项指标,得出了每一个规划方案的生存性水平。算例分析表明电网畅通性与电网脆弱性之间既相互联系又存在着一定的矛盾,证明了电网生存性体系将畅通性和脆弱性结合考虑的必要性。针对威胁电网生存性的两类元件的典型失效场景,分别提出了相应的扰动源准确定位方法。针对传统的发电机过电压保护在发电机并列运行场景下的选择性和速动性不足问题,提出了发电机并列运行场景下过电压源辨识策略,既能够在发电机励磁系统失灵时快速切除故障发电机,又能够在系统甩负荷等外部因素下充分发挥发电机AVR的电压调节作用以保证系统电压水平的恢复。分析了现有行波故障定位方法截断误差来源并提出了行波故障定位校正方法,在低采样率能够显著减小最大故障定位误差,在高采样率下能够提升高精度故障定位结果出现的概率。所提出的两种扰动源定位方法能够为电网应对元件失效场景的生存能力提供重要的保障。
[Abstract]:As an important infrastructure to ensure modern social and economic development and security and stability, the security of power grid has been highly concerned. In recent years, blackouts have revealed the inherent security risks of power grid itself, extreme natural disasters have exposed the vulnerability of power grid in dealing with harsh external environment, and the power grid is deliberately. The survivability of power grid in the environment of "internal and external troubles" is worth pondering. Many achievements have been made in the existing theory of power grid survivability assessment or vulnerability assessment, but there are still some imperfections, such as simply considering the vulnerability of power grid from the perspective of grid structure and ignoring electricity. The influence of network operation modes lacks in-depth analysis and evaluation of the interconnection between the equilibrium and vulnerability of power grid structure, and seldom makes a comprehensive evaluation of the survivability of power grid under normal operation mode and disturbance state from the angle of combining internal and external factors. This paper studies the existing and potential survival problems of power grid under normal operation mode and disturbance state, establishes the evaluation index system of power grid survivability and the method of locating disturbance sources. The main achievements of the work are summarized as follows:
A power transmission path analysis method based on power flow tracing method is proposed, which can analyze the deep characteristics of power flow through the surface of power flow and get all the power transmission paths between the "generator-load" nodes in the whole network. The electric distance is defined based on the power transmission path analysis to overcome the dependence on the network node only. Defects of the method of defining electrical distance can reflect the characteristics of power transmission more comprehensively. On this basis, the index and method for evaluating the smoothness of power transmission efficiency are constructed, and the important components that play a pivotal role in power transmission are identified.
Considering the influence of the spatial distribution characteristics of the key nodes and branches on the vulnerability of the power grid, a vulnerability assessment index and method considering the multi-source disturbances and the balancing characteristics of the power grid structure are proposed. The structural equalization index defines the spatial distance between nodes and branches, and puts forward the spatial distribution equalization of key nodes and the spatial distribution equalization of key branches. The vulnerability of the power grid under 2 modes of random failure and intentional attack is analyzed.
The index system and evaluation method of power grid survivability evaluation considering the unblocked, balanced and vulnerable of power grid are established. A hierarchical optimization method of survivability index weight based on AHP and improved grey relational degree method is proposed to synthesize all the indexes of power grid survivability into an organic whole.
A method of power network planning scheme based on power grid survivability assessment is proposed. Four planning schemes are constructed based on a typical practical power grid example. The survivability indices of each planning scheme are calculated and the survivability level of each planning scheme is obtained. The contradiction proves that it is necessary to consider the unimpeded and vulnerable of the grid survivability system.
Aiming at the typical failure scenarios of two kinds of components threatening the viability of power grid, the corresponding accurate locating methods of disturbance sources are proposed respectively. Aiming at the problems of selectivity and insufficient speed of traditional generator overvoltage protection under the scenario of generator parallel operation, the identification strategy of overvoltage source under the scenario of generator parallel operation is proposed. The fault generator can be quickly removed when the excitation system of the generator fails, and the voltage regulation function of the generator AVR can be brought into full play under the external factors such as system load rejection to ensure the recovery of the system voltage level. Sample rate can significantly reduce the maximum fault location error and increase the probability of high-precision fault location results at high sampling rate. The proposed two disturbance source location methods can provide an important guarantee for the survivability of the grid in response to component failure scenarios.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM732

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