Research And Analysis Of Messages In Secondary System Of Intelligent Substation

Intelligent substation is an important part of smart grid development.The electronic transformer that connects primary system with secondary system is the important equipment in the intelligent substation.The electric value that reacted by electronic transformer requires A/D conversion and digital processing,and then enter into the merged unit,and finally by the protective devices,measuring and control devices to receive data,in this process,it demanded the sampled data which before and after the merged unit,and the sampled data between each merged unit to maintain synchronized,and it will inevitably bring data synchronization problems.This paper uses interpolation method to achieve data synchronization of electronic transformer,and we based on the theory errors and carries simulation experiments of Lagrange linear interpolation,Lagrange quadratic interpolation algorithm and cubic Hermite interpolation algorithm.This paper proposes an improved cubic Hermite interpolation that could improve calculation accuracy and under higher harmonics the error of calculation is less,which can effectively solve the problem of data synchronization.For the problem that the abnormal communication may happen and cause the loss of sampled value during the transfer process,we propose an estimation algorithm,an improved cubic Hermite interpolation.In this paper,we have analyzed the estimation error of some interpolation algorithms in different packet loss scenario.The result has proved that the improved cubic Hermite interpolation algorithm has less error,and can be applied to estimate the lost packet of samples values message.In the smart substation,the message of Sampled Value(SV)and Generic Object Oriented Substation Event(GOOSE)is a main carrier to communicate and share information among smart devices,and plays an important role of protection,measuring and control in intelligent substation.As the very large density and flow of SV messages,high requirements are put forward for real-time recording and storing network packets device.In order to choose a suitable compression algorithm for SV message,we analyze the effect of multiple compression algorithms and decide to use Deflate algorithm.Then according to the characteristics of SV message,we have tested the effect of compression in different code window.The simulation results prove that the communication time and storage space of smart substation messages can be optimized by the Deflate algorithm.