Research On Identification Of Transmission Section And Coordination Strategy Of Protection And Control Measures With Multi-source Information

The cascading trip caused by power flow transfer is an important reason of large scale blackouts and power system collapse.Power flow transfer caused by line removal may result in the overloade of transmission section.Then,the improper action of backup protection and the unresponsive cooperation of control measures finally bring about the cascading trips and power system collapse.Accurately locating transmission section where the tripped line is,improving the performance of backup protection and perfecting the cooperation strategy of protection and control measures under overload are conducive to cutting off the development chain of cascading trips,which can guarantee the safe operation of the power system.The dissertation carried out the researches from the perspectives of "identification of transmission section","prevention of mal-operation of backup protection" and"coordination and cooperation of overload protection and control measures".A variety of protection and control means are coordinated to avoid cascading failures.The main work of the dissertation includes the following parts:(1)To solve the difficulty of accurate identification of transmission section,the methods to identify transmission section with the inductance coupling coefficient and side-path search results are proposed.Branch coupling coefficient is introduced with loop impedance matrix to avoid the complex decoupling process.The power flow transferring factor and graph-based path search method are used jointly.All side paths are searched to effectively avoid the omission of transmission section.(2)To prevent the misoperation of zone-? backup protection under power flow transfer,a correcting method based on multi-source information fusion is proposed.Information units covering different protected objects are built firstly.Based on the comprehensive calculation with the results of different units,the performance of zone-?backup protection is revised and improved to avoid the misoperation under power flow transfer.(3)For the coordination of protection and control measures under overload of transmission section,a progressive optimization model with bi-objective and the corresponding strategy are proposed.Protection,traditional emergency control,HVDC emergency power control measures are integrated together.Considering load loss and system safety,two-layer optimization objective is constructed.The(GA/improved SA)nested optimization algorithm is used to solve the mixed variable nonlinear programming problem.It is helpful for decreasing computation time.The proposed coordination strategy optimizes the adjustment effect of overload.(4)Based on the requirements of the above methods and schemes,the multi-source information processing architecture of protection and control system is proposed.The protection and control coordination center can analyze the protection and control resources.The calculation process of backup protection against misoperation is completed by the regional center.The coordination of protection and control measures can be implemented through the information interaction between coordination center and regional center.At the same time,the power grid partitioning methods are introduced to lay the foundation for the realization of proposed scheme.