Research On Wide-area Backup Protection Based On Integrated Decision-making Mode

The performance of traditional relay protections, which are based on local information,can’t meet the demand of the developing power system, as both the network frame andoperation condition are getting more and more complex. The wide use of WAMS and fiberoptic network also provides the right opportunity to develop wide area backup protection.In this thesis, the results of researches on system structure, protected zone divisionalgorithm, information fusion technology and communication model of wide area backupprotection are shown.Different system structures are compared to show the advantages of the centralizedcontrol structure. A new centralized control structure based on protected zone division isproposed, which will collect more information at the control center with lesscommunication cost.A protected zone division model is built according to three indexes proposed in thisthesis to evaluate the performance of protected zone division algorithm. The optimaldecision on protected zones is finally given by a new hierarchical partitioning method usinggenetic algorithm, which firstly searches for the main stations and then divides the powersystem into several parts around these stations. The hierarchical partitioning method canapplied to power systems of different sizes, and is highly efficient.The Lefevre combination formulas in D-S evidence theory are simplified here togreatly reduce computation load during its application in fault element identification. Faultelement will be identified by combining both the states of related traditional relayprotections and the analogue voltage and current values measured where these protectionslocated. The fault tolerance performance of this fault element identification algorithm islargely improved by using redundant information.An IEC61850based communication model which can be used in the fault elementidentification algorithm proposed above is built after defining new logic notes andproposing suitable information changing service model. This communication model can beused in different kind of wide area backup protections by changing the logic notes, which makes a good foundation for further study on communication system of wide areaprotection.