Research On Intelligent Substation Protection And Control Optimization Technology Based On Information Fusion

Relay protection is the first line of defense to ensure the safe operation of the power grid.With the integration of high proportion of renewable energy,the large power grid pattern of UHV and large capacity interconnected has been formed.On the one hand,higher requirements are put forward for the action performance of relay protection.On the other hand,the topology of power grid and the operation mode of system are more complicated,which further deteriorates the working conditions of existing relay protection.The traditional fixed value coordination protection only reflects the local information of the protected equipment,and there is a natural contradiction between the selectivity and sensitivity of the protection.The development of the power grid makes this contradiction more irreconcilable,and the key to solve this problem is to break the constraint that the protection only reflects the information of the protected equipment itself.Therefore,breaking the limitation of only using local information of the protection,information fusion is the fundamental way to solve the existing protection problems.The construction of smart grid,especially smart substation,provides effective technical support for relay protection to comprehensively utilize the information of the substation and adjacent substations.In this paper,the station and regional information are utilized to carry out innovative research on the working mode,composition principle,information reliability guarantee measures of relay protection and the coordination mechanism between protection and power grid security control.The following results are obtained.(1)Based on the analysis of several wide-area protection information fusion schemes,the composition mode and information fusion mechanism of a novel protection system with the intra-station centralized and inter-station distributed are proposed.The new schemes of station,inter-station local and remote backup protections based on protection action logic information fusion are constructed respectively,and the protection performance is greatly improved by using protection multivariate information.The simulation results show that the action time of the local backup protection is less than 100ms,and the action time of the remote backup protection is less than 500 ms,which are not affected by the system oscillation and overload.The presented protection schemes have passed the dynamic simulation experiment and have been applied in Jiaxing area of Zhejiang Province.(2)A distance protection scheme based on three-phase comprehensive information is proposed.Based on information theory,the corresponding relationship between fault electrical quantity characteristics and protection action behavior is analyzed,and the fault correlation characteristics of three-phase current and voltage during fault are fully excavated and utilized to form the blocking criterion based on feedforward neural network.Then,the accurate identification of system fault,overload,oscillation,PT disconnection and other working states is realized,and a novel distance protection scheme based on three-phase current and power comprehensive information is established.Finally,the simulation results show that the problem of maloperation of distance protection caused by system oscillation,overload and CT/PT disconnection is effectively addressed by presented protection scheme.(3)A reliability guarantee method of substation relay protection system based on redundant information is proposed.Firstly,the impact factors of abnormal data are analyzed,and the impacts of two typical abnormal data of SV message frame loss and abnormal large value on protection is further studied.Secondly,the reliability analysis model of substation protection system is established to find the weak link of protection system and provide the basis for improving its operation reliability.Next,the data error correction method of protection system based on redundant information is proposed,and the secondary system state estimation and physical constraints are utilized to realize the identification and substitution of abnormal data.Finaaly,the simulation results show that the proposed reliability guarantee measures avoid the misoperation or rejection of the protection system caused by the failure of the merging unit,and improve the operation reliability of the protection system.(4)A new security defense system framework of "regional coordination+distributed autonomy" is established.Based on the demand analysis of power grid development for the coordilation between relay protection and power grid security control,the information fusion and function optimization coordination mechanism of protection and power grid security control is proposed,and a new security defense framework of "regional coordination+distributed autonomy" is designed.On this basis,the typical application cases of protection and transient stability analysis,protection and emergency control,protection and active splitting coordination are studied and verified by simulation.The simulation results show that the new security defense system can not only optimize the protection function,but also further improve the coordination ability of protection and security control,which can effectively inhibit the occurrence and development of systematic accidents.