Understanding Of Transmission Section And The Research On Searching Method

The interconnection of large area power networks is studied for its optimization ofthe allocation of resources. Meanwhile, the complexity of the grid structure and difficultyof grid security analysis is increased. Security analysis for every single transmissionelement needs a large amount of computation and is hard to be applied to large powersystem online security analysis due to time consuming. Transmission section is defined asa collection of transmission elements closely associated with power grid security, oncedamaged, there could be serious results. Therefore, transmission section, as a monitoringand control object, is both an inevitable demand of large power system online securityanalysis and an effective method of coping with power network fault.Current research on transmission section is mainly developed from twoconsiderations:1) Based on power flow transferring analysis, how power flow transfersfrom overloaded line to other loops at the condition of overloaded line tripping off arestudied. Accordingly, the transmission section is configured by loops that experiencebigger power flow changes.2) Treat generation stations as units and reduce the grid scalebasing on geographic distribution and electrical property. The initial transmission sectioncould be searched from tie-line cut-sets, and be further trimmed to final transmissionsection by judging its consistency of power flow.On the basis of the existed literatures, this paper studied the theoretical analysis andsearching method of transmission section from the three perspectives of power flowtransferring section, transmission corridor and electromagnetic loop. Power flowtransferring section focuses on local power flow transfer range and is closely related withopen branch; Transmission corridor and the partition tie-line in close contact, focus on thetrend of network power flow between different regions; Electromagnetic loop is a specialcase of the transmission corridor, reflecting the multi-voltage coupling characteristicsbetween the different branches within the transmission corridor.By developing multi-angle understanding and analysis of the transmission section,this paper proposes a transmission section searching method that based on cut-vertex and path searching as well as a transmission corridor searching method that based on thetie-line nodes contraction partition. Compared with other searching methods, applyingcut-vertex could efficiently reduce the dimension of power grid model. K-shortest pathssearching could evade the transmission section missing and over-numbered which is thetypical drawback of the shortest path searching. The flexible selection method of k insteadof constant value also improves the algorithm adaptability. Electrical distance-basedmethod for determining the tie-lines complies with the actual power grid structure, nodescontraction partition process can ensure to the search algorithm based on tie-lines iscorrect and effective. The simulation of New England39-bus system and IEEE118-bussystem demonstrates the searching method of transmission section is correct and effective.