Research On Risk Assessment Of Power System Relay Protection Field Work

With the development of the national economy, our country continues to expand the scale of power grid, and the structure and operation mode of power grid become more and more complex, Planning operation and maintenance of power system faces a great challenge. The normal operation and maintenance of relay protection, as the last protective barrier to guarantee the security and stability of power grid,, plays an important role to the entire power system, so it is significant to research on the risk assessment and pre-control of relay protection field work.Firstly, this thesis overviews the content and related concepts of relay protection field work, summarizes the main accident types of relay protection field work, and analyzes the causes of each accident. Based on failure modes and effects analysis (FMEA) and A.D.Hall3D model model, this thesis identifies the risk in relay protection field work,determines the main factors of risk in each step of the work, and proposes appropriate preventive measures.Then, the fault tree and event tree models of relay protection field work has been constructed. The fault tree interpretates logical relationship of accidents risk, on the other hand the event tree develops mitigation measures. For a comprehensive analysis of the causes and consequences of the accident, this thesis introduces Bow-tie model to make the fault tree and event tree model integrated, so as to prevent, control or mitigate the risks.Finally, this thesis carries out a quantitative analysis of the risk in relay protection field work. With the date evaluated by site expert based on Delphi method, this thesis comprehensively uses fault tree analysis and fuzzy mathematics theory, solves the risk probability of relay protection field work. Then, the thesis use AHP to determine the weighting factors of index of risk consequences of fieldwork, and obtains the severity values of risk consequences of typical jobs through fuzzy comprehensive evaluation. On the basis of the calculation results, this thesis presents a mathematical modal of risk value considering environmental factors, and introduces risk matrix by dividing the risk level, thus to develop an early warning systemThis thesis combines a power grid "field work risk identification and control system" project, through the example of500kV transmission line relay protection upgrad work was presented.