Research On Wide Area Backup Protection Based On Centralized Decision-making

The performance of relay protection has a significant impact on the security and stability of the entire power system, for it is the key parts to provide satisfactory service to the power system, and it is"the first line of defense"of the safeguard of the power grid. As the development of power system, the problem of safeguard of power grid becomes more conspicuous. The power blackout of recent years point that the false and failure of relay trip is one of the key factor of large-area power-cuts. The traditional backup protection is based on the local information, it is coordinated by the trip time and setting values. As the growing of the power grid, it brings difficult for the setting and coordination. So, research of wide area protection based on wide area information is an effectual way to deal with the problem of power grid protection.Based on the comparison of the structural patterns, we choose the regional centralized configuration as the research object. The paper analyzes the structure of wide area protection, partition of power grid and fault component identification algorithm base of information fusion.First of all, the paper analyzes the research and application of the protective relay on wide area back up protection, then lead to broach information fusion technology to wide area protection. The application of information fusion is also introduced.In the section of structure pattern, the paper compares the benefits and drawbacks of IED distributed structure, station centralized structure and regional centralized structure in communication, reliability and realizability respects. The analysis shows that the regional centralized structure has good prospects for application for its simple communication structure and mature application foundation.A reasonable method of power grid protected zone division is one of the key technologies for the complex large power grid. Based on the graph theory, the paper gives the principle and method of protected zone division of regional centralized structure. It is made up of not only the weights of local station, but also the processing capacity of main substation. The example shows that the zone division method is feasible. In order to summarize the reliability of the protection algorithm based on longitudinal comparison principle, the paper analysis the capacity of identify the fault component in the case of lose or false of direction information. Then the conception of"extended area"is proposed. The use of extended area can determine the fault in a small zone under the condition of lost or false of direction information. The criterion of bus bar complete differential protection is also injected. The research indicates that the reliability of protection algorithm based on longitudinal comparison principle need to be strengthened.In order to improve the fault tolerance of the algorithm of recognition of fault component, the technology of multi-information fusion based on fault direction matrix is proposed. The principle of Similarity matrix is used to identify the fault component. The simulation shows that the fusion of trip information can restraint the negative effect brought by the lost or false of protection information. The fault tolerance of the algorithm is improved by the method.Finally the achieved research is concluded and future perspective is highlighted.