Simulation Research Of Computer Protective Relaying Algorithm

With the increasing capacity of power system and the expansion of power grid,the operation and management of power grid is becoming more and more complex,and the computer protective relaying technology also faces the unprecedented test.The algorithm determines the realization of different functions of the computer protective relaying device,being the soul of the computer protective relaying device.Therefore,aiming at the existing problems of computer protective relaying algorithm,optimization research is carried out,being conducive to the development of computer protective relaying device,which has better performance of reliability,selectivity,speedability and sensitivity,and also has the vital significance of ensuring the safe,stable and economic operation of power system,preventing the occurrence and expansion of the fault,and building the strong and smart grid.In the paper,with the computer protective relaying algorithm as the research object,research status and domestic as well as oversea development trend was studied deeply.Based on reading and analysis of domestic and foreign literature on the study of the computer protective relaying algorithm,some key problems of computer protective relaying algorithm on theory and application were studied.Some new computer protective relaying algorithms were proposed,comparing to the traditional algorithm,which have higher accuracy.In order to ensure the theoretical significance and practical value of the proposed computer protective relaying algorithm,the effectiveness of the new methods were verified by modeling and simulation.The research of the paper has three aspects:1.The development status domestic and oversea computer protective relaying algorithms were reviewed.The current principle of computer protective relaying algorithm was analyzed,and the characteristics of various algorithms were evaluated;2.Aiming at the shortage of the traditional microcomputer protection algorithm in theory and practical application,firstly a simplified algorithm based on frequency tracking derivative is proposed on the basis of the traditional sampling value product algorithm,a sampling algorithm based on real-time frequency value product was proposed;In order to improve the accuracy of the differential equation algorithm in the long distance transmission line,a new differential equation algorithm based on RLC model was put forward;According to the characteristics of sinusoidal function,a new algorithm based on derivative fault current was proposed,which can separate the fundamental frequency component of the fault current from the decaying aperiodic component.three kinds of microcomputer protection algorithm were introduced in detail;evaluating the algorithm characteristics of three kinds of microcomputer protection;the Matlab/Simulink simulation model were established to verify the improved algorithm and proved the algorithms are effective and reliable;3.On the basis of the above three kinds of computer protective relaying algorithm simulation,with the help of ActiveX technology and the excellent visual programming environment of Visual Basic 6,the microcomputer protection algorithm Simulink simulation system was developed.Based on the two sampling value product algorithm based on real-time frequency,the function of each module of the new system was verified.The result proved that the algorithm simulation system of Simulink computer protective relaying VB platform with computing efficiency reserved completely,based on Matlab/Simulink at the same time,the characteristics of Visual Basic were given play to simple operation,friendly interface,overcoming the complex operation of Simulink and the shortage of the interface being not intuitive.